The Foot and Ankle in Rheumatoid Arthritis

Pathomechanics and the application of gait analysis in rheumatoid arthritis 43 AB 0.15 1200 Peak pressure (kPa) 1000 800 600 400 200 0 MTP2 MTP3 MTP4 MTP 5 MTP1 Forefoot region Figure 2.23 (A) masking technique for regional pressure analysis. (B) distribution and magnitude of peak pressure across the MTP joint regions in comparison with normal range (area between dashed lines represent the normal range [mean ±2SD]). contact is made, but only for 0.18 s in late stance and four basic patterns (medial, medial-central, central, function is diminished as the peak pressure values lateral). In RA, these basic patterns are influenced by are under normal limits for this region. Interestingly, the extent of forefoot pain and deformity, and any pressure distribution is normal in the 1st metatarsal compensation strategy to off-load sites and by the head region and the hallux. transfer of load forward from the heel and midfoot particularly when these sites are deformed and The utility of these data emerges when we consider painful. In Figure 2.25, we noticed our patient the clinical picture (Fig. 2.24). This 59-year-old male was uncomfortable when standing and was rolling the patient presented with longstanding bilateral forefoot foot outwards to off-load the medial forefoot region. pain, deformity of his toes and self-reported changes The patient, with 2 months of disease, was tender at to his walking style (slow, avoidance of uneven sur- the medial three MTP joints, the first and second of faces, and careful foot placement). On examination, which had synovitis confirmed by ultrasonography. the MTP and interphalangeal joints were retracted Early in the disease there were no major foot deformi- with claw-toe deformity, although range of motion ties, but the daylight sign confirmed spreading of the was within normal limits. The fatty-fibro padding was forefoot. She had no plantar pressure lesions, and displaced anteriorly and dorsally and moderate callus when the peak pressures were averaged the loading and adventitious bursae were observed over the pattern was medial according to the Hughes 2nd–5th MTP joints (Figure 2.24A and B). He tested Classification. However, when individual steps were positive to the metatarsal squeeze test, and all 5 considered, two other patterns were observed on sub- MTP joints were tender on direct palpation. sequent steps and we believe this demonstrates a Radiographically, all 5 MTP joints scored 5 on the Scott variable off-loading pattern in response to the medial modification of the Larsen index, indicating severe forefoot symptoms. erosion and deformity. The tarsus and ankles of both feet were unremarkable. The sites of high pressures Clinical utility of plantar pressure measurement are entirely consistent with the pathology and clinical has been demonstrated in a number of studies. features at the MTP joints (Fig. 2.24C). Sharma et al. (1979) for instance, showed that forefoot loading was associated with lesser toe deformity and The foot pressure distribution pattern in able- increased severity of clinical symptoms and radi- bodied persons is variable and Hughes et al. (1991), ographic joint damage. In three cohorts of patients using a discriminant analysis technique, classified

44 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Figure 2.24 Forefoot clinical features showing lesser toe deformities, prominent metatarsal heads, and bursa and callosities overlying the MTP joints (A) and (B). Peak pressure profile in presented case (C) and foot of age and sex matched normal subject (D). Figure 2.25 Patient with early disease off-loading the medial forefoot region, which was both tender and inflamed. The daylight sign is seen on standing at the 1st and 2nd toe clefts. The pressure distribution pattern is variable ranging from central to medial. The symptoms (RAI: Ritchie Articular Index scores for tenderness ranging in severity from 0 to 3), presence of inflammation (HRUS: high- resolution ultrasound), and peak plantar pressure (PP) values for each MTP joint are presented in the table.

Pathomechanics and the application of gait analysis in rheumatoid arthritis 45 presenting with progressively worse radiological instances, the callus has an underlying adventitious damage (not based on any current scoring system), bursa and both serve to increase the contact area over loading on the hallux, second and lateral toes (regional which the forces are distributed. Hence the debate as analysis) were markedly reduced in comparison with to whether these lesions are protective or harmful normal with significantly less loading in the lateral toe (Woodburn et al. 2000, Davys et al. 2005). We do regions (Sharma 1979). The area of toe contact and the know, however, that elevated focal pressures are force generation capacity of the lesser toes appear crit- associated with the development of ulceration in ical in relation to abnormally high peak pressures in some feet and three pressure profiles are shown in the forefoot (Collis & Jayson 1972, Sharma 1979, Figure 2.27. In each case, the peak pressures are in Simkin 1981, Minns & Craxford 1984, Soames et al. excess of normal values, and are experienced for pro- 1985). In Figure 2.26, a series of six feet are presented longed periods during stance. Extensive deformity, with varying severity of forefoot impairment charac- bone erosion and fatty-fibro padding displacement terized, if viewed from left to right, with increasing are important in all three cases and, characteristically, loss of toe function. In each case, focal areas of high the ulcer sites have steep pressure gradients from the pressure with a sharp gradient from adjacent sites adjacent normal or under-loaded skin sites. Toe func- were observed and consistent with MTP deformity tion is universally non-existent. including hallux valgus and claw and hammer toe. These patterns are observed in patients who have pre- Attention to underlying structure is important and dominantly forefoot disease and in all cases a well- four groups (Sharma et al. 1979, Soames et al. 1985, defined medial longitudinal arch is present. This Tuna et al. 2004, Davys et al. 2005) noted higher pres- serves to decrease the contact area proximal to the sures in patients with more erosive disease in the MTP metatarsal head region in some cases and this is well joints. These joints are frequently subluxed or dislo- demonstrated in the right most foot. cated and through erosion have irregular surfaces and sharp spikes. When the fatty-fibro padding is displaced The case series above perfectly illustrates why it is it is of little surprise that these feet have sharp focal impossible to attempt to define a typical pattern of pressures, severe symptoms and are at risk from ulcer- forefoot loading in patients with RA. In addition to ation. The pathomechanics of this process has been well deformity, plantar pressure measurement may be described by Stainsby and others in rheumatoid arthri- affected by local factors such as skin and soft-tissue tis (Dixon 1969, Mann & Coughlin 1979, Stainsby 1997, thickness, plantar callosities (Sharma 1979, Woodburn Briggs 2003). Briefly, synovitis and effusion leads to & Helliwell 1996) and the extent of bony erosion at capsular stretching, which results in loss of integrity of the MTP joints (Sharma 1979, Soames et al. 1985, Tuna the collateral ligaments (hypothetically with greater et al. 2004). Sites of forefoot plantar callus are proxy involvement of the medial collateral ligaments that indicators of localized high pressure and these are leads to fibular toe drift) and capsule itself. The plantar useful to detect during clinical examination. In most plate moves distally around the metatarsal head (see Figure 2.26 Peak pressure distribution profiles for six patients with rheumatoid arthritis with varying severity of foot impairment characterized from left to right with increasing loss of toe function and decreased forefoot contact area.

46 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Figure 2.27 Peak pressure distribution profiles for three When foot pressures are measured, the duration of patients with forefoot ulceration. Ulcer sites are indicated with pressure experienced at each site must be considered a red circle. alongside the absolute peak pressure value and this is generally longer in RA patients than normal, so Fig. 2.28), and in severe deformity as frequently moderate-high pressures may also be experienced encountered in RA, the metatarsal head dislocates for longer in discrete regions such as the forefoot. If through the proximal joint capsule of the MTP and the plotted as a function of time, the pressure integral or two slips of the plantar aponeurosis where attached at impulse can also be higher (Turner et al. 2003, Otter the sides of the plantar plate. Dorsiflexion stress leads et al. 2004). This, however, mostly depends on symp- to subluxation and eventual dislocation at the MTP toms because those patients with severe forefoot pain joints. Erosion may lead to bony spikes and the normal at sites of high peak pressure can compensate by fatty-fibro padding under the metatarsal heads is delaying load transfer into the forefoot and then rap- displaced dorso-anteriorly. Secondary pressure lesions idly off-loading by eliminating the third rocker func- occur in the skin overlying the metatarsal head, often tion (Simkin 1981, Soames et al. 1985). This can be accompanied by an adventitious bursa. assessed by measuring the time spent by and the velocity of the COP through the heel, midfoot, fore- foot and toe regions of the foot. A typical case is shown in Figure 2.29. In the able-bodied subject, the first rocker function of the foot is shown by the rapid forward progression of the COP in the heel region, followed by forward progression of the COP between 0.3 and 0.5 m/s through the midfoot, forefoot and toe at approximately 22%, 42% and 85% of stance phase respectively. By contrast, the patient has no first rocker function and maintains the COP in the heel region until 70% of stance. The velocity rises sharply through the mid- and forefoot regions, peaking at 2.0 m/s, with the forefoot and toe contact together only making 11% of stance phase contact. The foot is AB 2 3 1 4 Figure 2.28 (A) typical advanced forefoot deformity in rheumatoid arthritis with clawing of the lesser toes. (B) Schematic showing eroded metatarsal head [1], dorsal and anterior displacement of the plantar plate [2] and forefoot fat pad [3] with overlying metatarsal head callosity [4] (adapted from Briggs 2003).

Pathomechanics and the application of gait analysis in rheumatoid arthritis 47 A Heel Midfoot Forefoot 2.5 2.0 VCoP (m/s) 1.5 1.0 0.5 0.0 20.0 40.0 60.0 80.0 100.0 0.0 Heel Midfoot Forefoot B 2.5 2.0 VCoP (m/s) 1.5 1.0 0.5 0.0 20.0 40.0 60.0 80.0 100.0 0.0 % Stance Figure 2.29 Progression of the centre of pressure (COP) through the foot. The velocity of the COP is plotted as a function of time in (A) a typical able-bodied individual and (B) a patient with severe forefoot impairment (pain located to the central MTP joints with overlying callosities and claw toe deformity). lifted from the ground indicating loss of the second The planovalgus foot in RA reveals interesting and third rocker functions. changes in pressure distribution and these have been described in a number of studies (Stockley et al. Further work is necessary to elucidate further the 1990, Woodburn & Helliwell 1996, Turner et al. 2003). compensation strategies adopted by patients to allevi- Stockley’s group found an association between valgus ate symptoms. They appear to be highly variable. The heel deformity and elevated medial forefoot pressures case above is predominantly compensating, using a in patients who had undergone forefoot arthroplasty sagittal plane strategy, but contrasts that with two (Stockley et al. 1990). Since these patients fared worse further patients shown in Figure 2.30. These patients surgically than their counterparts with normal heel both had persistent and severe forefoot symptoms alignment, they concluded that load transfer from the starting early in the course of their disease and had heel to forefoot was an important factor in foot func- compensated by holding the foot in a stiff varus posi- tion. A later study confirmed this showing a similar tion to off-load the more painful medial side. The medial distribution of forefoot peak pressures and long-term consequence is fixed varus foot deformity callus patterns in patients with valgus heel deformity with elevated pressures and new symptoms at the (Woodburn & Helliwell 1996). More recently, a lateral forefoot.

48 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Figure 2.30 Lateral off-loading the painful medial forefoot force-time integrals were greater, and lateral forefoot region in two patients with rheumatoid arthritis. off-loading was present in the group with RA (Fig. 2.31). The findings from this study confirm the comprehensive study of 23 cases with clinically observation that pes planovalgus may have detri- defined pes planovalgus incorporated spatial-tempo- mental effects on the entire structure and function of ral and 3D ankle joint complex kinematics with plan- the foot. tar pressure measurement (Turner et al. 2003). Typical pronatory motion for the ankle joint complex The progression of pes planovalgus has been esti- was found with changes to the plantar pressure and mated in radiographic studies, but these techniques force distribution patterns. The patients walked are not advisable for routine clinical use. Plantar pres- slower and remained in double-support longer and sure measurement offers quick assessment of overall these compensatory mechanisms reduced the ampli- foot geometry and loading characteristics. From the tude of the pressure and force variables, but may Turner et al. study of 2003 six cases are presented in have served to increase the cumulative load because Figure 2.32 to show the progressive features of pes of the longer contact time. This was demonstrated in planovalgus. From left to right, progressive off- the heel region and the effect may be beneficial to loading in the lateral heel and forefoot regions with reduce painful symptoms in the peri-talar region increased loading medially and increased contact area during the loading response. As expected, medial in the midfoot region can be observed. Two extreme longitudinal arch collapse resulted in a large increase cases on the far right are shown with severe midfoot in the contact area in the midfoot and medial forefoot collapse with high focal pressures in the navicular- as the soft-tissue and bony architecture changed. medial cuneiform region consistent with sites of pain Furthermore, higher midfoot peak pressures and pres- and overlying callus. sure-time integrals may be related to tissue viability problems and skin callosities were noted over the Plantar pressure measurement is useful in deter- talonavicular joint area in several patients with mining functional changes in our patients who have severe deformity. Internal joint loads may be harmful multiple impairments throughout the foot. Figure in the midfoot region where peak force, force-time 2.33 shows the profile from a female patient in her integrals and contact time are increased and this was 60s with over 25 years of disease duration. Although demonstrated in the patients. In agreement with her disease is well controlled on biologic therapy she others, forefoot loading was altered from a central has persistent forefoot pain. She presented with to a medial pattern, peak pressure and pressure- and hallux valgus fixed at ~15˚ of dorsiflexion, claw toes, which were retracted and non-weightbearing when standing, and a valgus heel deformity with low medial longitudinal arch profile. Her walking speed was slow at 0.78 m/s, cadence 113 steps/min, cycle time 1.06 s and stride length 0.83 m. In the forefoot the normal geometry of the MTP parabola had been disturbed through a combination of disease activity (erosion and deformity) and surgical intervention (arthrodesis and arthroplasty). The sharp distal mar- gins of the eroded 5th MTP and arthrodesed 1st MTP were evident on plain X-ray. The fatty-fibro padding was displaced anteriorly and a callus was present over the 1st MTP joint. The heel fat pad was atrophied and a firm palpable mass consistent with a nodule or bursa present over the medial calcaneal tubercle. From her pressure profile a number of features can be determined. The superimposed COP shows normal progression in the heel region, delay in the midfoot and rapid progression through the fore- foot consistent with an off-loading pattern described earlier. The elevated medial heel pressures are located as the site of the plantar nodule or bursa. Although her arch profile is low, it has stiffened in that posture rather than collapse as the pressure profile shows a normal arch distribution.

Pathomechanics and the application of gait analysis in rheumatoid arthritis 49 -71.8 (-122.8, -20.7) 425 123 122 20 24 (57) (47) (6) (4) -3.9 (-5.3, 2.5) 353 (183) 306 333 (-67.9, 14.4) 148 110 108 1.7 (-10.3, 13.7) 11 12 (194) (184()108)-26.7 (144) (52) (35) (3) (2) 411 (355) 16 14 16 (5) (3) (10) 17 315 90 (8) (123) (32) 44 -0.2 (-0.8, 0.5) 0.5 (-1.8, 2.9) (110658)(16007)(941343).9 (-0.3, 28.1) 36 (26) 13.3 (7.2, 19.5) (43) 96.4 (23.3, 169.4) 31 6 (19) 71 (5) 274 18 2 (31) (94) 322 (2) 16 34.3 (1, 67.6) (11) 107 (92) 18.2 (-73.2, 26).7 121 (76) 80 3.4 (2.4, 4.4) (3) (310341()314435) (107) (28) 16 17 16 (3) (3) -48 (-73.2, -22.7) (3) Rheumatoid arthritis 85 Normal group (37) 26.8 (11, 42.5) -38.8 (76.3, 1.36) 36 (13.8, 58) -0.5 (-1.2, 0.3) -0.2 (-0.9, 0.5) Peak Pressure (kPa) Pressure: time integral (kPa.sec) Contact AREA (cm−2) 34 10 12 84 83 84 85 27 (9) -7.2 (-10.5, -4) (5) (3) -1.6 (-2.8, -0.4) (11) (11) (11) (11) 27 (14) 9 8 (3) -0.9 (-3.6, 1.9) 20 (7) (3) 9 (8) (6) 8 81 81 (3) (12) (9) 24 25 -1.3 (-2.1, -0.5) (14) (9) 1.5 (-0.9, 3.9) 1.8 (0.8, -2.8) 63 -7.7 (-4.3, 2.4) 12 (10) 11 5 3 0.6 (-2, 3.3) 56 (15) (5) (3) -0.2 (-3.1, 2.7) (19) 5.3 (1.7, 9) 63 -1.0 (-4.3, 2.2) (7) 1.5 (0.4, 2.9) 1 (1) 46 (11) 3 (14) (4) 34 1.7 (1, 2.4) 31 (7) 25 30 0.7 (0.4, 0.9) 11 9.8 (5.3, 14.4) 68 (8) (6) 3 (7) 9 1 (1) (0.3) 8 (4) 7 (12) (5) (3) (2) 59 67 (10) -4.6 (-6.1, -3.1) 1.7 (0.9, -2.6) (12) 60 (10) -3.6 (-5.5, -1.6) 3 (1.6, 4.3) 8.5 (5.4, 11.5) Peak Force (N) Force: time integral (N.sec) Contact time (% ROP) Figure 2.31 Summary plantar pressure and force data for the right foot of patients (shaded) and normative group. The vertical bars are scaled to the absolute mean values with SD in parentheses. The mean group differences are presented with 95% confidence intervals of the difference given in parentheses. The foot is divided into regions of interest including the medial and lateral heel and the midfoot and medial, central and lateral forefoot. Six summary variables are presented (From Turner et al. 2003). Figure 2.32 Peak pressure distribution profiles for six patients with varying severity of pes planovalgus. Armed with this information one can go about resulted in high medial pressures concentrated over the systematically linking structural and functional impair- first metatarsal head, which is dorsiflexed and immo- ment with knowledge of the disease pathology, symp- bile. This is further exacerbated by the fixed dorsiflexed toms, compensation strategies and effects of past position of the 1st MTP with the hallux undergoing interventions. In the forefoot, the heel position has minimal ground contact. Laterally, the eroded 5th

50 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Figure 2.33 (A) The heel is in valgus. (B) The medial longitudinal arch height is low but not fully collapsed and the midfoot joints are stiff. (C) The lesser toes are retracted, deformed and non-weight bearing. (D) The 1st MTP is arthrodesed, the 2nd, 3rd and 4th MTP joints are severely eroded, and the 5th MTP has undergone excision of the metatarsal head and proximal phalanx. (E) Peak pressure profile with vertical ground reaction and centre-of-pressure line superimposed. metatarsal head may be responsible for the spike of difficult to compare due to methodological differ- pressure at the MTP joint region. The 3rd metatarsal ences with the pressure measurement and variance in head was slightly longer and prominent on palpa- the patient cohorts, surgical procedures undertaken tion and the toe made no ground contact explaining and follow-up time. As a rule, detrimental peak pres- the elevated pressure here. Pain is significant sures can be reduced in the forefoot with arthroplasty enough to slow the walking speed and shorten the procedures and these tend to be associated with clin- stride length. ical improvement in symptoms and function (Betts et al. 1988, Dereymaeker et al. 1997, Bitzan 1997). The pressure information from this case was used Betts and colleagues found that pre- and post-operative to assist surgical planning and it is here that PPM has pressure analysis allowed them to appraise their sur- been used as a functional outcome tool (Betts et al. gical techniques after encountering good pressure 1988, Phillipson et al. 1994, Dereymaeker et al. 1997, reduction in the central metatarsal heads, but not at Bitzan 1997). Findings have been variable and

Pathomechanics and the application of gait analysis in rheumatoid arthritis 51 the 1st or 5th (Betts et al. 1988). They attributed this KEY POINTS to a shallow arc created during the metatarsal head resection thereby transferring load from the central ● Plantar pressure (P) is defined as the force (F) per metatarsal heads outwards to the first and fifth. unit area (A) (P=F/A). Dereymaeker et al. (1997) detected a reduction of abnormal high pressure areas in just over 50% of ● Plantar pressure distribution can be measured cases with increased toe loading and resolution using platform or in-shoe systems. of plantar callosities at 35 months post-surgery. After a similar period, by contrast, Phillipson and col- ● The pressure footprint can be used to determine leagues found an increase in both peak pressure and the plantar geometry the pressure-time integral in 15 patients, although not all were RA. This was partly attributed to ● Peak pressure and the pressure-time integral are increased walking speed following surgery, although frequently higher than normal in the forefoot in this change was not formally reported and the great- RA and are associated with impairment including est changes were reported under the first metatarsal pain, stiffness and deformity. head and associated with recurrent callosities. Clearly, more controlled studies with well-defined ● In pes planovalgus collapse of the medial longi- end points are required to clarify some of the anom- tudinal arch is associated with increased contact alies arising from the current literature. and force in the midfoot region. Elsewhere, in-shoe pressure measurement has ● Plantar pressure relief, pain reduction and func- been used to assess the off-loading properties of cus- tional improvement have been reported following tom and prefabricated orthotic devices. Shrader and surgical and non-surgical interventions for Siegel, from the National Institutes of Health, pres- symptomatic forefoot disease in RA. ent a very detailed and excellent case history, show- ing the effective reduction of peak pressure and MUSCLE FUNCTION (SEE ALSO pressure-time integral in the forefoot using a CHAPTERS 3 AND 4) custom-fabricated orthosis (Shrader & Siegel 2003). The pressure relief was accompanied by improve- Determining muscle function from electromyography ment to symptoms and ability to perform activities has been rarely studied in RA. Perry (1992) suggested of daily living requiring standing and walking. In that the loss of muscle strength was a major pathome- more controlled studies, both prefabricated and chanical factor in foot disease in RA. Two mechanisms custom orthoses have been shown to be effective for were postulated: (1) inflammation causes joint and reducing forefoot pressure and improving symptoms soft-tissue pain that inhibits muscle function, thereby with moderate evidence to suggest custom devices reducing the force transmission at painful joint sites are more effective (Hodge et al. 1999, Li 2000). The and (2) through the above action motion is decreased, Leeds randomized controlled trial of custom which results in reduced activity and the development orthoses manufactured in carbon-graphite, followed of secondary muscle weakness. This was demon- 101 patients with early disease and mobile correctable strated in a single RA patient with gastrocnemius and valgus heel deformity for 30 months (Woodburn soleus weakness secondary to MTP joint inflammation 2001). Results showed effective off-loading of the showing loss of third rocker function as described ear- medial forefoot region, increased contact area and lier (Perry 1992). The same group used fine-wire elec- force in the midfoot and decreased pressure in the tromyography (EMG) to study extrinsic foot muscle heel region, all favourable changes for the foot type function in patients with RA with and without being treated. valgus deformity of the foot (Keenan et al. 1991). This work eloquently showed increased intensity Noteworthy is the use of padded hosiery as these and duration of activity of the tibialis posterior, too, in the short term, have pressure-relieving function supposedly in an effort to support the medial longi- similar to orthotics. In Leeds, the effect of scalpel tudinal arch in those patients with valgus heel defor- debridement on forefoot pressures at callus sites has mity. This group believed the compensatory action of also been studied and showed no significant differ- tibialis posterior was due to primary weakness in calf ence in the change between a real and sham procedure muscles that, despite increased activity on EMG test- (Davys et al. 2005). Again, these areas will benefit from ing, were weak on manual muscle testing. Combined further studies that are well controlled, adequately pow- with motion, structural and clinical data, the inte- ered to detect pressure differences and appropriately grated approach demonstrated in this work facilitates disease-staged. a better understanding of changes in foot function resulting from primary pathology. Electromyography

52 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS is one of the more difficult techniques to undertake using valid and reliable global and foot-specific ques- during routine gait analysis and we have yet to fully tionnaires. integrate this technique to the approaches described above. CONCLUSIONS ENERGY CONSUMPTION This chapter has summarized currently available gait analysis techniques that are available to the clinician When patients who have RA walk with painful joints and researcher. We have appraised the available infor- and undertake compensatory strategies we can pos- mation and where evidence was lacking appropri- tulate that the gait is less energy efficient than nor- ate cases were presented to illustrate the use of the mal. Measurement of metabolic energy expenditure various techniques in our own laboratory. Plantar pres- is a useful global measure of overall gait performance sure measurement probably represents the extent that and allows the physiological cost of pathological gait most clinical units will invest in gait equipment and we to be estimated. Measurement techniques are not believe this is reasonable given its ease of use and routinely performed since they typically involve col- affordability. This technique yields valuable infor- lection and analysis of blood gases and heart rate mation on foot structure and function in RA. We are whilst walking or exercising. The physiological cost steadily refining other techniques and using them for index (PCI) was previously proposed as an objective clinical research and practice. 3D joint kinematic and measure of disability and as an outcome for inter- kinetic analyses are more difficult to perform and vention studies in RA (Steven et al. 1993, Kavlak et al. interpret, but we have shown some valuable uses 2003). The index is based on the observation that any in patients at various stages of the disease to detect voluntary increase in walking speed demands an changes associated with impairment and as compensa- increase in energy expenditure that is relatively dis- tion strategies. We hope that gait analysis will be proportionate in disabled persons. Past studies have become more readily available in the future, as it has shown that NSAID therapy leads to a statistically sig- important uses for determining the structural and func- nificant improvement in the PCI, but that the tional changes in the foot brought about by inflamma- improvement was not correlated with conventional tion in the joints and soft-tissues of the foot. Moreover, clinical measurements such as tender/swollen joints, treatment planning and evaluation can be greatly aided pain score or ESR (Steven et al. 1983). Kavlak and by gait information, especially in complex cases under- colleagues (2003) found a significant improvement in going surgical intervention. In terms of clinical foot pain, step and stride length, and the physiological research, gait analysis will be used to drive experimen- cost index after 3 months of foot orthotic therapy. tal work aimed at further advancing our core knowl- Beyond these two applications, the PCI has not been edge and, in translational studies, inform future widely adopted in clinical research and this is under- development of customized approaches to footwear standable when disability can be easily measured and orthosis manufacture as well as foot surgery. References Bouysset M, Tebib JG, Weil G, Lejeune E, Bouvier M Deformation of the adult rheumatoid rearfoot. Betts RP, Stockley I, Getty CJ, Rowley DI, Duckworth T, A radiographic study. Clinical Rheumatology Franks CI Foot pressure studies in the assessment of 1987; 6: 539–544. forefoot arthroplasty in the rheumatoid foot. Foot and Ankle 1988; 8: 315–326. Briggs PJ Controversies and perils. Reconstruction of the rheumatoid forefoot. The Stainsby operation. Techniques Bilney B, Morris M, Webster K Concurrent related validity in Orthopaedics 2003; 18: 303–310. of the GAITRite walkway system for quantification of the spatial and temporal parameters of gait. Gait Posture Buczek FL, Kepple TM, Lohmann Siegel K, Stanhope SJ 2003; 7: 68–74. Translational and rotational joint power terms in a six degree-of-freedom model of the normal ankle complex. Bitzan P, Giurea A, Wanivenhaus A Plantar pressure Journal of Biomechanics 1994; 27: 1447–1457. distribution after resection of the metatarsal heads in rheumatoid arthritis. Foot and Ankle International 1997; Carson MC, Harrington ME, Thompson N, O’Connor JJ and 18: 391–397. Theologis TN Kinematic analysis of a multi-segment foot model for research and clinical applications: a Bouysset M, Tebib J, Tavernier T et al. Posterior tibial repeatability analysis. Journal of Biomechanics tendon and subtalar joint complex in rheumatoid 2001; 34: 1299–1307. arthritis: magnetic resonance imaging study. Journal of Rheumatology 2003; 30: 1951–1954.

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54 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Perry J Gait Analysis. Normal and Pathological Function. rheumatoid arthritis. Rheumatology International 2005; Slack, Inc., Thorofare, NJ, 1992. 26(1): 42–47. Turner DE, Woodburn J, Helliwell PS, Cornwall ME, Phillipson A, Dhar S, Linge K, McCabe C, Klenerman L Emery P Pes planovalgus in rheumatoid arthritis: Forefoot arthroplasty and changes in plantar foot a descriptive and analytical study of foot function pressures. Foot and Ankle International 1994; 15: determined by gait analysis. Musculoskeletal Care 595–598. 2003; 1: 21–33. Woodburn J Plantar pressure and footprint analysis in Platto MJ, O’Connell PG, Hicks JE, Gerber LH The rheumatoid arthritis: a comparison of patients classified relationship of pain and deformity of the rheumatoid by 3D MRI image analysis of the subtalar and midtarsal foot to gait and an index of functional limitation. Journal joints. 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The relationship between valgus patient with rheumatoid arthritis treated with custom- heel deformity and the distribution of forefoot plantar made foot orthoses and shoe modifications. Physical pressures and callosities in rheumatoid arthritis. Annals Therapy 1997; 77: 296–305. of Rheumatic Diseases 1996; 55: 806–810. Woodburn J, Helliwell PS, Barker S Three-dimensional Shrader JA, Siegel KL. Nonoperative management of kinematics at the ankle joint complex in rheumatoid functional hallux limitus in a patient with rheumatoid arthritis patients with painful valgus deformity of the arthritis. Physical Therapy 2003; 83: 831–843. rearfoot. Rheumatology 2002; 41: 1406–1412. Woodburn J, Helliwell PS, Barker S Changes in three- Siegel KL, Kepple TM, O’Connell PG, Gerber LH, Stanhope dimensional joint kinematics supports the continuous SJ A technique to evaluate foot function during the use of foot orthoses in the management of painful stance phase of gait. Foot & Ankle 1995; 16: 764–770. rearfoot deformity in rheumatoid arthritis. Journal of Rheumatology 2003; 30: 2356–2364. Simkin A The dynamic vertical force distribution during Woodburn J, Nelson KM, Lohmann Siegel K, Kepple TM, level walking under normal and rheumatic feet. Gerber LH Multisegment foot motion during gait: proof Rheumatology Rehabilitation 1981; 20: 88–97. of concept in rheumatoid arthritis. Journal of Rheumatology 2004; 31: 1918–1927. Soames RW, Carter PG, Towle JA The rheumatoid foot Woodburn J, Stableford Z, Helliwell PS Preliminary during gait. In: Whittle M and Harris D (eds) investigation of debridement of plantar callosities in Biomechanical Measurement in Orthopaedic Practice. rheumatoid arthritis. Rheumatology 2000; 39: 652–654. Oxford University Press. New York, 1985; pp. 167–178. Woodburn J, Turner DE, Helliwell PS Barker S A preliminary study determining the feasibility of Spiegel TM and Spiegel JS Rheumatoid arthritis in the foot electromagnetic tracking for kinematics at the ankle joint and ankle – diagnosis, pathology, and treatment. Foot & complex. Rheumatology 1999; 38: 1260–1268. Ankle 1982; 2: 318–324. Woodburn J, Udupa JK, Hirsch BE et al.The geometrical architecture of the subtalar and midtarsal joints in Stainsby GD Pathological anatomy and the dynamic effect rheumatoid arthritis based on MR imaging. Arthritis of the displaced plantar plate and the importance of the Rheum 2002; 46: 3168–3177. integrity of the plantar plate–deep transverse metatarsal Yao L, Gentili A, Cracchiolo A MR imaging findings in ligament tie-bar. Annals of the Royal College of Surgery spring ligament insufficiency. Skeletal Radiology 1999; of England 1997; 79: 58–68. 28: 245–250. Steven MM, Capell HA, Sturrock RD, MacGregor The Physiological cost index of gait (PCG): a new technique for evaluating nonsteroidal anti-inflammatory drugs in rheumatoid arthritis. British Journal of Rheumatology 1983; 22: 141–145. Stockley I, Betts RP, Rowley DI, Getty CJM, Duckworth T The importance of valgus hindfoot in forefoot surgery in rheumatoid arthritis. Journal of Bone and Joint Surgery 1990; 72–B: 705–708. Tuna H, Birtane M, Tastekin N, Kokino S Pedobarography and its relation to radiologic erosion scores in

Pathomechanics and the application of gait analysis in rheumatoid arthritis 55 Further reading Whittle M Gait Analysis. An Introduction. 3rd Edition. Butterworth Heinemann Health, 2001. Perry J Gait Analysis. Normal and Pathological Function. Thorofare, NJ: Slack, Inc, 1992. Robertson G, Caldwell G, Hamill J, Kamen G, Whittlesey S Research Methods in Biomechanics. Champaign, Illinois. Human Kinetics, 2004

Color Plate 2.20 Plantar pressure distribution pattern from a typical patient with rheumatoid arthritis recorded from (A) platform device and (B) in-shoe device. Both techniques capture the lack of lesser toe contact, Pressure distribution is similar over the metatarsal head region, but the superior spatial resolution of the platform device captures the sharp focal pressure in the middle three metatarsal heads. Furthermore, the in-shoe system is measured at the interface of the foot and contoured custom orthosis, hence, the reduced forefoot pressures and the increased contact are in the midfoot region in comparison with the platform-based technique. Color Plate 2.12 The clinical picture is that of severe pes planovalgus (B). Color Plate 2.16 Sagittal plane ankle joint net muscular Color Plate 2.21 Foot geometry parameters taken from the moments, power profiles and pressure distribution pattern with footprint of (A) able-bodied subject and (B) patient with severe COP overlaid in (A) able-bodied adult matched with (B) pes planovalgus. A standard algorithm defines each parameter rheumatoid arthritis case (as presented in Figure 2.15). as a distance or angle measurements taken from anatomically relevant reference lines overlaid on the pressure pattern.

Color Plate 2.22 Plantar pressure distribution pattern in a patient with rheumatoid arthritis. The first frame in the upper left corner is recorded shortly after heel-strike (0.06 s) and then presented every 0.06 s until toe-off in the lower right frame (0.09 s). Color Plate 2.23 (A) masking technique for regional pressure analysis.

Color Plate 2.25 Patient with early disease off-loading the medial forefoot region, which was both tender and inflamed. The daylight sign is seen on standing at the 1st and 2nd toe clefts. The pressure distribution pattern is variable ranging from central to medial. The symptoms (RAI: Ritchie Articular Index scores for tenderness ranging in severity from 0 to 3), presence of inflammation (HRUS: high-resolution ultrasound), and peak plantar pressure (PP) values for each MTP joint are presented in the table. Color Plate 2.26 Peak pressure distribution profiles for six patients with rheumatoid arthritis with varying severity of foot impairment characterized from left to right with increasing loss of toe function and decreased forefoot contact area.

Color Plate 2.27 Peak pressure distribution profiles for three patients with forefoot ulceration. Ulcer sites are indicated with a red circle. Color Plate 2.30 Lateral off-loading the painful medial forefoot region in two patients with rheumatoid arthritis. Color Plate 2.29 Progression of the centre of pressure (COP) through the foot. The velocity of the COP is plotted as a function of time in (A) a typical able-bodied individual and (B) a patient with severe forefoot impairment (pain located to the central MTP joints with overlying callosities and claw toe deformity).

Color Plate 2.32 Peak pressure distribution profiles for six patients with varying severity of pes planovalgus. Color Plate 2.33 (A) The heel is in valgus. (B) The medial longitudinal arch height is low but not fully collapsed and the midfoot joints are stiff. (C) The lesser toes are retracted, deformed and non-weight bearing. (D) The 1st MTP is arthrodesed, the 2nd, 3rd and 4th MTP joints are severely eroded, and the 5th MTP has undergone excision of the metatarsal head and proximal phalanx. (E) Peak pressure profile with vertical ground reaction and centre-of-pressure line superimposed.

57 Chapter 3 Clinical features of the foot in rheumatoid arthritis CHAPTER STRUCTURE JOINT DISEASE: UNDERSTANDING HOW SYNOVITIS PRESENTS IN THE FOOT Joint disease: understanding how synovitis presents AND CAUSES THE CHANGES SEEN in the foot and causes the changes seen in IN RHEUMATOID ARTHRITIS rheumatoid arthritis 57 In the section on the pathogenesis of rheumatoid Joint symptoms in early and late disease 59 arthritis (RA) (Chapter 1), the putative triggers and Joint stiffness and early-morning stiffness 60 mechanisms behind the development of synovitis, Modifying factors and associated symptoms 61 the hallmark of RA, were described. In RA, synovitis Functional status 63 can develop in any joint, simultaneously or consecu- Enthesopathy 64 tively. There are no rules that govern which joint or Bursae, skin and nail disease 65 group of joints become involved at any particular Extra-articular features 65 time. In fact, it is likely that virtually all synovial joints have some degree of inflammation if we were to look hard enough, by synovial biopsy, for exam- ple. Imaging modalities, such as ultrasound (U/S) and magnetic resonance imaging (MRI) have shown that clinical examination is a crude technique for detecting synovial inflammation at an early stage (see Chapter 5). Given that synovial inflammation is probably widespread, what sort of factors might govern the pro- gression of inflammation and the onset of bone dam- age and deformity? With respect to the foot, the most important factor must be joint loading. What governs the degree of joint loading in the foot? Body weight is an important variable in this respect, but we don’t know how important this is, having no epidemio- logical data to advise us. Ambulation, both in quantity and quality, is important. There is some evidence that stride length is a significant indicator of joint loading (see section on Gait in Chapter 2) but, all other things being equal, the amount of time spent upright will greatly influence the cumulative loading of the lower limb joints. While we would not advocate a return to the times when patients with early RA were admitted to hospital, there to rest in bed for up to 3 months,

58 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS methods to reduce joint loading and abnormal forces capsule adapts and becomes distended and lax so that should be a priority in early disease. the intra-articular pressure falls. Are any of the joints of the foot and ankle more sus- The sub-talar joint is particularly vulnerable to ceptible to excessive joint loading? There is evidence inflammation in RA. There are a number of reasons for that the talo-crural joint is rarely involved by this. Firstly, as mentioned above, the sub-talar is a osteoarthritis and it has been suggested that this joint complex joint the stability of which may be readily in particular has a good surface area to load ratio compromised by inflammation. Secondly, pronation at despite having to withstand forces of up to four times this joint is not an uncommon finding in ‘normal’ body weight during normal ambulation (Swann & people, the prevalence being around 25%. Thirdly, Seedhom 1993). For theoretical reasons, therefore, it abnormal gait patterns resulting from painful forefoot might be expected that the ankle joint is involved less disease may lead to excessive pronation of the foot frequently and later than other joints in this region. and the resulting pes planovalgus deformity (see The evidence for this is contradictory, however, as was Figs. 1.3, 2.6). Fourthly, inflammation and attenuation discussed in the section on the Epidemiology of Foot of medial juxta-articular structures such as the tibialis Disease in Chapter 1. On the whole the evidence posterior tendon and the deltoid ligament will points to a lower prevalence of disease in the talo- exacerbate and contribute to advancing deformity crural joint, but it must be recognized that many of (see Fig. 2.10). these figures were obtained by clinical examination. However, figures from radiological surveys (i.e. of Compensation mechanisms occurring in neigh- deformity and erosion) support the low prevalence bouring structures are often adequate for the purpose and later onset of disease in this joint. of minimizing functional limitation imposed by spe- cific, localized pathology. Symptoms will arise, how- The progression of disease and the appearance of ever, if the compensations are inadequate or when the joint deformity will also be influenced by the structure act of compensation itself precipitates other dysfunc- and function of the joint. The subtalar joint, for tion. An example of this process is in the development example, is a complex structure that permits a tripla- of a varus hindfoot deformity in RA. This inverted nar movement through which forces are transmitted positional deformity of the calcaneus contrasts with between the ground and the body during locomotion. the more usual valgus deformity and is seen in only Although the anterior and posterior parts of the joint 3–5% of people with RA. The mechanism for the varus are normally separated, this separation is soon lost in deformity is not well understood, but it is seen in RA as inflammatory changes cause attenuation of joint patients with severe and painful forefoot disease on structures. In fact, the loss of the normal anatomical the medial side and so it is thought likely that it is a boundaries between joints is a frequent occurrence in structural consequence of a functional change brought established RA. This is readily apparent when contrast about by offloading the painful joints. is injected into the joints; a common finding is com- munication between the anterior and posterior parts In the mid-tarsal region one joint in particular of the subtalar joint and communication between seems to be involved early and is often the source of these and the talo-crural joint (see Fig. 6.4) and within much discomfort in RA; the talo-navicular joint. The the mid-tarsal and mid-carpal joints. reason this joint is so pivotal in this disease is not entirely clear, other than some of the factors adduced The subtalar joint also contains important ligamen- to be important in the sub-talar joint will apply here. tous structures that contribute to the stability of the These include a low joint surface-area-to-load ratio. In ankle joint complex; the talo-calcaneal and cervical lig- addition, increasingly large forces will come to bear on aments in particular. Intra-articular ligaments such as this joint as the medial arch of the foot begins to dis- these are particularly vulnerable to the advancing place inferiorly with progression of disease in the sub- rheumatoid pannus. However, another mechanism talar joint and as a result of the inflammatory changes that contributes to the loss of joint stability is the lax- in the ligamentous structures of the foot. ity in joint capsule consequent to tense intra-articular effusions. When a joint first becomes inflamed the In the metatarsophalangeal joints early inflamma- intra-articular pressure is high due to the effusion tory change may cause, through disruption of the joint occurring within the normal anatomical confines of capsule, widening of adjacent toes (daylight sign: see the joint capsule. The high pressure may contribute, Fig. 2.15) and pressure on the inter-digital nerve incidentally, to articular damage due to ischaemic (Morton’s ‘neuroma’ – see below). These clinical point- changes (as the pressure of the effusion exceeds that of ers are unique to this area, possibly as a result of arterial pressure) (Blake et al. 1989, Jayson & Dixon the anatomy of the metatarsophalangeal joint and the 1970). With time and persistence, however, the joint surrounding structures in the web space. Extension of synovial pannus into the contiguous ligamentous

Clinical features of the foot in rheumatoid arthritis 59 structures, such as the deep transverse metatarsal liga- Tenosynovitis is frequently seen in the major tendons ment, will cause disruption of this structure and thus that cross the ankle joint where they are encased in widening of the forefoot at this point. The subsequent sheaths lined with a synovial membrane. The most fre- development of the typical changes seen in RA are a quent areas are the peroneal tendons on the lateral consequence both of synovitis, attenuation of joint aspect (see Fig. 4.9) and tibialis posterior on the medial capsule and ligaments, altered mechanical forces and aspect, but changes are also often seen anteriorly unequal pull of the long and intrinsic tendons crossing beneath the extensor retinaculum. The inflammation the joints (see Fig. 2.24). may arise de novo in these tendon sheaths, but is occasionally seen as an extension of the inflammatory Morton’s ‘neuroma’ is a misnomer in this situation. process in adjacent joints: a phenomenon seen occa- Although Morton originally described the syndrome sionally at arthrography. Importantly, sustained in association with a swelling of the inter-digital nerve inflammation in the tendon sheaths will eventually adjacent to the metatarsophalangeal joint, it seems lead to deterioration of the collagenous substance of likely that in RA it is synovitis in the joint that is caus- the tendon itself with subsequent rupture. The tendon ing compression of the nerve (Awerbuch et al. 1982). may be functionally inadequate, however, purely in The presentation is the same: a sharp pain radiating the presence of inflammation as the individual seeks into the ipsilateral digit, worse on weight bearing to avoid loading the affected part (see Chapter 7). and reproduced by pressure across the metatarso- phalangeal joints. In summary, the hallmark changes of RA (inflam- matory synovitis) may affect any synovial tissue and, Understanding the effects of synovitis in although the pathological processes are common to all the foot in rheumatoid arthritis joints, the effects of the inflammation will be modified according to local factors, including the joint anatomy, ● Joint loading is an important factor interacting the periarticular structures and the individual’s with synovitis to produce joint deformity. Many response to the painful pathological processes that are factors contribute to this including body weight underway in the feet. Finally, as befits our adoption of and stride length. the ICF model, it is worth considering what effect footwear and walking surfaces have on the processes of ● Synovial pannus weakens intra-articular and synovitis in the foot affected by RA. Dixon has argued periarticular ligamentous structures. Joint effu- that some of the deformities of the foot in RA, particu- sions distort the joint capsule. larly the forefoot, are the result of wearing ill-fitting shoes (Dixon 1987). His comments are aimed mainly at ● Certain joints deform early – the subtalar joint is the narrow fashion ‘court’ shoes worn by women in vulnerable because of its complex anatomical Western society that contribute to the common deformi- structure, vulnerable supporting structures and ties seen in the hallux. In support of his contention is the pivotal biomechanical role in walking. common absence of this deformity in developing coun- tries. Whether this is true or not, patients with RA com- ● Similarly the talo-navicular joint is frequently monly complain of painful feet and an inability to wear involved because of its pivotal position and comfortable footwear. There is no doubt that once the function in the integrity of the medial lingitudi- disease progresses the resulting pain and ensuing defor- nal arch. mity make obtaining comfortable footwear that fits a difficult task. On the other hand, many of the patients ● Forefoot deformity, manifest as widening, supplied with footwear designed to accommodate their occurs early and may manifest as difficulty get- foot problems do not ultimately wear the new shoes ting footwear to fit. (Williams & Meacher 2001). This remains an important area for further work both from the perspective of our ● Sesamoiditis in the forefoot may be an impor- patients, whose mobility is compromised as a result, and tant cause of symptoms. from the perspective of the NHS, whose finite resources must be used in the most cost-effective manner. Further manifestations of the inflammatory process are manifest in the sesamoid bones and in the tendons JOINT SYMPTOMS IN EARLY with synovial sheaths. The major sesamoid bones, in AND LATE DISEASE particular those associated with the hallux, may develop an associated inflammatory synovitis as their Two of the cardinal symptoms of rheumatoid arthritis anatomy reveals a synovial sheath around the bone. (joint pain and stiffness) are manifest early in the foot Rheumatoid synovitis then results in what is essen- tially ‘sesamoiditis’, a major consequence of which is pain and altered gait to avoid loading the area.

60 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS and ankle. Symptoms change with the duration and because of neuropathy. Health professionals are now stage of disease, and these will be discussed separately advocating the use of a stick or a frame, but these in relation to the underlying pathological changes. walking aids are problematic because of upper-limb involvement. The patient sees the dreaded wheelchair At onset RA comes as a completely new set of sen- looming, understandably becoming more despondent. sory experiences and frequently results in a level of Their once dainty feet are now deformed and painful, impairment and disability that both shocks and dis- they can’t wear a decent shoe and previous enjoyable mays the sufferer. What were previously regarded as activities, such as walking and dancing, are now automatic activities, walking and running, are sud- impossible. denly very difficult and present significant obstacles to mobility. Pain is usually felt under the metatarso- This may seem a negative account of the natural phalangeal joints and is worst in the early morning history of foot and ankle symptoms of RA, but many and evening when weight bearing. Patients describe of these symptoms are experienced and patients do their feet as ‘throbbing’. At this stage, and long before entertain thoughts such as those given above. It is there is deformity of the forefoot with callus forma- important for health professionals to be aware of this tion, patients will describe a sensation of walking with when treating patients; we know we can do a lot to pebbles in their shoes. Inflammation of the mid-tarsal help and even prevent these symptoms and disability, and sub-talar joints can be equally disabling and but we should appreciate that patients may not, results in an aversion to walking on uneven ground or initially at least, share these views. cobbles. A particular environmental obstacle in this respect is the so called ‘tactile pavement’ now in wide- JOINT STIFFNESS AND EARLY-MORNING spread use at junctions to help visually disabled STIFFNESS pedestrians. Stiffness, particularly early-morning stiffness, is a At the early stages patients may prefer to walk bare- symptom eagerly sought by rheumatologists, since it is foot as their usual footwear aggravates their symptoms. believed to be a cardinal symptom of inflammation. Attempts to find more comfortable footwear, which is Indeed, such is the importance attached to this symp- also cosmetically acceptable, results in the complaint of tom that it was included as one of the original items multiple pairs of discarded shoes, none of which are used for diagnosis of RA and was retained in the 1987 worn. Many patients find ‘trainers’ the most comfort- revised diagnostic classification criteria (Arnett et al. able option. As the disease progresses the desire is to 1988, Ropes et al. 1959). Further, the duration of morn- find wider fitting shoes to accommodate the broaden- ing stiffness is often used both in the clinic and in ing forefoot. research studies as a guide to disease activity. However, other conditions may cause stiffness: osteoarthritis, in Later in the process of the disease the patient may particular, can also cause early-morning stiffness and have symptoms that relate to deformity and associ- may also be associated with stiffness that comes on after ated consequences. At this stage patients may only be a period of inactivity such as sitting in a chair: the able to walk with shoes on as their bare feet are no so-called articular gelling. Some authors have sug- longer able to provide a stable base for ambulation. gested that it is difficult to separate osteoarthritis from Hammer toes will rub on the toe box of the shoe RA just on the duration of morning stiffness, although and some patients will wear, as a consequence, only the severity of morning stiffness (as measured on a sandals. Hard callus under subluxed metatarsal heads visual analogue scale) seems a better discriminator will cause discomfort in addition to adventitial bursae (Hazes et al. 1993). Of course, it is often difficult for the associated with these. A mid-foot that is collapsing patient to comply with the request to quantify the will cause excessive activity in tibialis posterior (if the timing of stiffness as often it doesn’t just disappear; in tendon is still intact) and consequent medial calf pain. metrology there is a tendency to quantify even that Nodules in the heel pad will cause significant pain and which cannot be measured, certainly not precisely. interfere with mobility. Discussion of the significance of the symptom of At all stages of disease foot morbidity will impair stiffness requires some definition of terms. In engi- mobility and cause much anger and frustration. neering terms, stiffness is defined as the resistance to Patients say they feel slowed down and that they slow movement. Not surprisingly, this may not be the defi- others down. No longer can they run for a bus, or nition used by patients. In fact, when a patient uses the across the road. Everything must be planned in term ‘stiffness’, or responds to a question about this advance. As the disease progresses patients feel unsafe symptom, they may be referring to a wide spectrum of and can’t keep their balance. This is due partly to loss definitions (Helliwell & Wright 1990). Using an array of proprioception from damaged joints (in all lower limb joints), partly weakness and, in some cases,

Clinical features of the foot in rheumatoid arthritis 61 Joint stiffness in rheumatoid arthritis found an appropriate increase in articular stiffness in RA (Helliwell et al. 1995). Earlier measurements on the ● Prolonged early morning joint stiffness is an finger were able to be revisited and corrected for important symptom muscle wasting, thus revealing the erroneous nature of these original measurements. ● It is one of the criteria used for classification of the disease It is clear, therefore, that we can quantify the symptom of joint stiffness, but that the effort ● Duration of early morning stiffness is often used required probably outweighs the precision and relia- to reflect disease activity bility of the result. This comment is particularly true if we are using stiffness as a measure of joint inflam- ● Patients confuse the symptoms of joint pain and mation; it is quicker and easier and, probably more stiffness but describe a lack of movement and relevant, to measure a serum marker of inflammation resistance to movement such as the C reactive protein. The symptom itself is still worth seeking as it may provide a guide to ● Joint stiffness can be quantified and can be used disease activity and may provide prior information to measure change in inflammation in the joint about limited range of movement at the joints. This but it is quicker and easier and, probably more may be especially relevant at the ankle joint where a relevant, to measure a serum marker of inflam- limited range of dorsiflexion is readily perceptible mation such as the C reactive protein and may be identified by the patient as a cause of altered gait. It is doubtful that patients will be aware of definitions provided by a broad selection of of reduced movement at other joints as often the patients, Helliwell was able to demonstrate that functional range is small and even a very restricted patients using the term ‘stiffness’ predominantly range may still permit adequate function (Woodburn mean ‘resistance to movement’ or ‘lack of movement’, et al. 2002). but nevertheless often confuse stiffness with pain (Helliwell 1995). MODIFYING FACTORS AND ASSOCIATED SYMPTOMS Given the definition of stiffness as resistance to movement, and given the importance of the symptom RA is a disease of remissions and relapses. Although in the diagnosis and monitoring of the disease, it was overall involvement of the foot and ankle is common, inevitable that engineers would attempt to devise the degree of involvement is fairly unpredictable and instruments to quantify this symptom. Original is dependent on a range of intrinsic and extrinsic fac- devices were cumbersome and tended to cause the tors. The foot contributes to limitation in walking abil- patient some discomfort (Wright et al. 1969), but later ity in some three-quarters of patients with RA, and is machines were light and portable and enabled meas- the primary or sole cause of walking limitation in urement of a large number of patients in the clinic sit- about one-quarter (Kerry et al. 1994). The symptoms of uation (Howe et al. 1985). Unfortunately, using such a RA and their effects in the foot can be modified, either device Helliwell was unable to demonstrate any positively or negatively, by a range of mediators, increase in articular stiffness in this disorder (Helliwell many of which can be influenced by the patient or the et al. 1988b). rheumatology team (see Fig. 3.1). Further work made the situation clearer. When Intrinsic factors affecting rheumatoid arthritis measuring stiffness it is generally necessary to move symptoms in the foot the distal part of the joint with the patient relaxed while at the same time measuring the resistance to Disease activity movement. The mistake that was made was to assume that the articular structures were the major tissues The effect of RA on the foot is closely related to disease contributing to stiffness when measured this way. In activity and, by extension, its control (Scott et al. 2000). fact, later experiments revealed that the muscles serv- Increased RA activity is known to lead to greater pain ing the tendons that cross the joint contribute about (Covic et al. 2003) and considerable impairment of 50% to total joint stiffness. It was generally known that walking function (O’Connell et al. 1998, Wickman et al. muscle wasting is a feature of RA and this was demon- 2004). The most widely used measure of disease strated using hand dynamometry and, later, by the activity is the Disease Activity Score (DAS), which is measurement of forearm circumference (Helliwell an index derived from counts of tender and swollen et al. 1987, Helliwell & Jackson 1994). Finally, a study of joints, erythrocyte sedimentation rate, and global wrist stiffness using an entirely new system of meas- urement, and correcting for forearm circumference,

62 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Contribution of factors to disablement in RA through decreased physical activities (Morgan et al. 1997). Change in BMI is not thought to be associated Disease duration with disease activity however (Morgan et al. 1997) and, perhaps surprisingly, patients with lower BMI in 3% Depression one study demonstrated more substantial change in ESR 3% Larsen scores over 2 years than those with higher BMI (Kaufmann et al. 2003). 5% Psychological status In the early stages of the disease, the best predictor Signs and syptoms 17% of the severity of functional impairment appears to be disease activity, but as the disease progresses joint 14% damage is more important. Forty percent of maximal joint damage occurs in the first 20 years of disease, Education although the earliest degeneration is most aggressive and results in some 16% of damage occurring in the Functional limitations 4% first 5 years (Scott et al. 2000). 11% Demographics Soft-tissue involvement may contribute to symp- 2% toms. Bursitis, tenosynovitis and enthesopathy may complicate the presentation of the articular disease. In Unexplained later disease callus formation and the presence of 41% adventitious bursae may make a significant contribu- tion to symptom presentation. Figure 3.1 Contributors to disability in rheumatoid arthritis. Extra-articular features such as vasculitis, ulcera- health measured by a visual analogue scale (van der tion and neuropathy (see below) may also add to Heijde et al. 1990). The original DAS score and the trun- the symptom complex, usually in the latter stages of cated 28 joint version (DAS-28) are well validated and disease. are used widely as a measure of disease activity (see Chapter 8). Inability to maintain own foot care The variability of the disease process is evidenced There are no formal data on the capacity of people by the degree of intra-individual variation in func- with RA to maintain their own foot care, but anecdotal tional scores over time within individuals (Wells et al. reports suggest that limitations in manual dexterity 1993). This is especially true in early disease where and in spinal flexibility, coupled with joint restriction, functional measures such as the Health Assessment all combine to lead to difficulties with maintaining Questionnaire (HAQ: see Chapter 8) vary with disease foot care. Hygiene may become problematic, although activity. In general, good medical control will gener- it has been suggested that this is more a concern to cli- ally improve walking ability in patients with RA nicians than to patients (Macran et al. 2003), but inabil- (Hamilton et al. 2001). ity to continue with nail care and control of callosities has the potential to contribute to symptoms. Inability Innate intrinsic factors to moisturize the skin of the feet can increase the rate of callus re-growth, and fissures may lead to oppor- Intrinsic factors such as age and gender are also tunistic infection. known to affect impairment. These factors are unalter- able and so are often dismissed, but warrant recogni- Extrinsic factors affecting rheumatoid arthritis tion. It is known for example that HAQ scores worsen symptoms in the foot (environmental factors with age (Anderson et al. 1988, Sokka et al. 2003), of the ICF) which reflects the accumulation of joint damage asso- ciated with the disease, as well as the functional limi- Psycho-social, socio-cultural and lifestyle tations associated with the natural ageing process demands (Anderson 1988). Poorer functional scores are also reported by women than men, although it is not clear The impact of living, long-term, with a chronic and why (Escalante & Del Rincon 1999, Thompson & painful disease has profound effects on the patients’ Pegley 1991). perceptions of themselves, their surroundings, and the disease itself. It is has been proposed recently that psy- Cultural and ethnic factors have been reported to chosocial factors, such as psychological status, learned be influential in RA (Griffiths et al. 2000). helplessness, and self-efficacy explain nearly one-fifth of the disability associated in rheumatoid arthritis and, A high BMI of >30 is known to be associated with an increased risk of developing RA (OR=3.74) (Symmons et al. 1997) and this may impact on the dis- ease course, as indicated above. Patients with RA are prone to becoming more obese over time, possibly

Clinical features of the foot in rheumatoid arthritis 63 as such, have been significantly undervalued previ- FUNCTIONAL STATUS ously (Escalante & Del Rincon 1999). People with RA have a chronic pain condition and all the psycho-social An understanding of functional status is important to consequences associated with this. Over time, pain those managing patients with RA because functional pathways become increasingly sensitized, and the status represents, for many patients, the bottom-line as threshold for generating and passing pain messages far as the impact of their disease is concerned. Type lowers leading to increased severity of symptoms and severity of pain, and the local effects of inflamma- (Gaston-Johansson & Gustafsson 1990). Depression tory joint disease have already been discussed and and hopelessness will adversely affect motivation and these factors are important in their own right. They do, coping (Whalley et al. 1997). In the longer term, nega- however, represent only part of the picture, as it is tive stress-vulnerability factors and poor social support changes in functional status that will influence are also known to be detrimental to overall function, patients ability to participate fully in their activities of although the short-term influence of these factors work, social roles and leisure. A patient’s functional appears less significant (Evers et al. 2003). status will of course be affected by the severity and type of symptoms, although function will in turn also Reduced capacity to undertake valued leisure or affect symptoms (Anderson et al. 1988, Chen et al. home-role activities can result in higher indices of 2003, Escalante & Del Rincon 1999). A detailed discus- depression, but conflicts between functional capacity sion of the various measures of patient functional and demands of work also result in high levels of status is presented in Chapter 8. work instability and lost productivity (Puolakka et al. 2004). It is known that the impairment secondary to Joint pain presents both a physical and psychologi- RA results in some one-third of patients retiring from cal barrier to normal function. Tasks generally take work within 5 years, and one-half retiring within 10 longer, and physically demanding tasks may appear years due to decline in physical function (Yelin et al. especially daunting. In addition, patients with RA 1987, Yelin et al. 1980), although the varying demands often report increased levels of fatigue and weakness, of specific work roles mean that the misfit between which makes a range of activities of daily living more functional status and continued employment can be draining. variable (Escalante & Del Rincon 2002). Even in early disease, the effect on functional status More subtle socio-cultural factors include cultural causes a threat to continued employment, and this link background and ethnicity, level of education and is continued into established disease (Barrett et al. occupation/income as well as marital status and social 2000). Functional status will worsen steadily over the support (Escalante & Del Rincon 2002, Gaston- course of the disease in most people (Hazes 2003), but Johansson & Gustafsson 1990, Hewlett et al. 2002), variations in disease activity are highly influential. although the effects of these are not well understood, Patients experiencing a flare in their arthritis may find, particularly in relation to the foot. therefore, that their symptoms are worse, and their functional capacity temporarily reduced during a Environmental factors can influence symptoms and flare, even in longstanding disease (Drossaers-Bakker function, with factors such as walking surface, pres- et al. 1999, Hazes 2003). During a flare, patients will ence of uneven terrain, steps and stairs, contributing to typically find the duration of morning stiffness the misfit between capacity and functional demands increased, as is the severity of the stiffness. Morning (Escalante & Del Rincon 2002). stiffness is problematic to working people as it reduces functional capacity during a busy period of the day, Footwear although for all sufferers it necessitates prioritization of activities. Increased disease activity affecting the Footwear can be either detrimental to symptoms in upper limbs will make it more difficult for patients to the foot or can be used therapeutically to improve an undertake basic activities of daily living that require existing disease state. Patients will often report prob- manual dexterity or the capacity to stretch or to lift, lems with their footwear, as standard retail footwear such as dressing, washing and cooking. Increased is often poorly suited to the altered structure of the disease activity in the lower limb likewise brings its rheumatoid foot. Problems can occur with fitting due own problems, as foot pain is known to impact on to deformity, or with accommodation of insoles or functional status even in the general population orthoses. Off-the-shelf orthopaedic footwear has been (Benvenuti et al. 1995, Chen et al. 2003, Leveille et al. shown to result in immediate improvement in walk- 1998). Damage to the large joints accumulating over ing function (Fransen & Edmonds 1997), and its time affects function significantly in its own right and bespoke nature should result in improved comfort is often further compounded by associated damage in levels. The role of footwear is discussed in more detail in Chapter 6.

64 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS small joints such as those in the foot (Drossaers-Bakker elsewhere in the skeleton. Additionally, Benjamin has et al. 2000). Activities requiring standing for any introduced the concept of ‘functional’ entheses. period of time may become problematic, posing prob- Functional entheses occur where tendinous and liga- lems for people whose work requires standing, or for mentous structures, while not actually attaching to undertaking domestic duties such as dish washing or bone, are adjacent and in a close relationship to the ironing. Discomfort associated with dynamic activities underlying bone. Forces, both shear and direct, occur- such as walking will limit the distances that can be ring as a result of this juxtaposition effectively result covered, will increase the time taken to undertake in an enthesis at this point (Benjamin & McGonagle tasks requiring walking (O’Connell et al. 1998, Platto 2001). Often there is a bursa between the tendon and et al. 1991) and contribute to increased fatigue (Chen the bone: an example would be the gluteal tendon as it et al. 2003). passes round the greater trochanter of the femur. Examples in the foot are the tendons of the peroneals Other factors affecting functional status are less and tibialis posterior as they pass around the lateral explicitly related to the physical manifestations of the and medial malleoli respectively. disease. Psychological factors have been shown to be important, with poorer functional status associated Traditionally, enthesitis has been one of the hall- with depression (Anderson et al. 1988, Hazes 2003), marks of the seronegative spondyloarthropathies: while those with stress-vulnerability profiles better ankylosing spondylitis, psoriatic arthritis and reactive suited to coping, show less disability (Evers et al. 2003). arthritis (Wright & Moll 1976). The traditional sites for Equally interesting is the relationship between socio- enthesopathy in this group of disorders have been the economic factors and functional status, as it has been heel (the insertion of the plantar fascia into the medial demonstrated that patients with a poorer socio-eco- tubercle of the calcaneum and the insertion of the nomic background show greater functional impairment Achilles tendon into the posterior aspect of the calca- and a poorer disease course generally than those with neum), around the pelvis, the sacroiliac joints and the less deprivation (ERAS-Study-Group 2000). The reason inter-vertebral ligaments. However, to reflect the for this is again unclear but does reflect the increased widespread distribution of enthuses, an index of morbidity from other disorders in this group. enthesitis has been developed that takes in palpable entheses from a number of other locations (Mander Foot involvement generally is a significant predic- et al. 1987). The Mander index scores the degree of ten- tor of impaired functional status (Wickman et al. 2004). derness at 18 possible locations in the spine and upper Progressive structural change in the hindfoot leads to and lower limbs. In clinical practice, however, many permanent diminishment of functional ability and patients with ankylosing spondylitis have an enthesis may, in turn, contribute to structural changes in neigh- score of zero and there are problems with inter-rater bouring joints, which exacerbate the loss of function. reliability. As a result of these limitations, a much Inflammation of the midfoot region can be particularly reduced version has been introduced (Heuft- disabling because of its coupling with the hindfoot Dorenbosch et al. 2003). (Astion et al. 1997). Patients find it difficult to com- pensate for functional loss in the mid-foot region. In Clinically, it is still believed that the two enthesitis the forefoot, in early disease, involvement of the sites at the heel are important and readily accessible metatarsophalangeal joints leads to pain in the fore- and that involvement of these sites is a good differen- foot and difficulties for the patient in loading this part tiating feature between seronegative spondylo- of the foot (Turner 2003). Patients often complain of a arthropathies and other inflammatory arthritides. feeling of pebbles in the shoes. If the symptoms are McGonagle and colleagues have been at the forefront confined to one or two joints then the patient may be of rekindling interest in this topic. They have subse- able to retain function by compensation mechanisms quently studied calcaneal enthesopathy using MRI in such as offloading on the other, less painful joints 17 cases of early spondyloarthropathy (including four (O’Connell et al. 1998). While this may have other cases of psoriatic arthritis, three cases of reactive arthri- undesirable consequences, such as the development of tis and three cases of ankylosing spondylitis) and 11 structural changes in the foot (see above), it minimizes cases of non-inflammatory heel pain (McGonagle et al. the impact on global function. 2002). Bone oedema at entheseal insertions was seen in both inflammatory and non-inflammatory conditions, ENTHESOPATHY but was found to be more severe in the spondylo- arthropathy cases. Calcaneal spurs occurred with equal The enthesis is the point of attachment of ligament frequency between the two classes of disorder. or tendon to bone. There are, therefore, literally hundreds of entheses in the foot and many more Calcaneal enthesopathy has also been studied using ultrasonography by an Italian group (Falsetti P

Clinical features of the foot in rheumatoid arthritis 65 et al. 2003). Spur formation, both posteriorly and Figure 3.2 Callus formation under the metatarsophalangeal inferiorly was common in erosive osteoarthritis, nodal joints with deep haemorrhage, indicating incipient ulceration. osteoarthritis, psoriatic arthritis, and rheumatoid arthritis, but was less frequently found in a non- the callus is usually carried out, but the callus can be arthritic control group. However, erosive changes at expected to re-grow within 1–6 weeks, creating a need the enthesis were only found in psoriatic arthritis (5% for ongoing care. Offloading of the area may be help- posterior, 1% inferior) and RA (12% posterior, 6% ful in limiting callus regrowth and can be achieved inferior), a surprising result in view of the enthesitis through the use of a rigid functional foot orthosis to hypothesis (McGonagle et al. 1998). redistribute forces to the mid foot or simple forefoot padding (see Chapter 6). It would appear, therefore, that calcaneal spurs and erosions occur reasonably frequently in RA, an obser- Abnormalities of the nails are frequently seen in vation made clinically in the original large series by clinical practice, although there has been no system- Vainio (Vainio 1991). It is also worth remembering that atic study of these in RA. Difficulty with hand func- the retrocalcaneal bursa is a synovial lined structure tion due to arthritis of the small joints of the hand, and so will be vulnerable to the inflammatory process coupled with involvement of large joints of the upper of RA per se, independent of any associated problems and lower limb, may also make it difficult for the in the adjacent enthesis. The many other anatomical patient to reach and cut the toe nails. This may lead to and functional entheses in the foot may also be infection around the nail bed manifest as paronychia involved and contribute to symptoms in this disorder. and ingrowing toe nail. Long-term immunosuppres- sion of the disease may also play a part in the patho- BURSAE, SKIN AND NAIL DISEASE genesis of infection around the nail and within the nail by fungi and yeasts. A bursa is an enclosed space or sac that may contain fluid and may be lined by synovial-like tissue. EXTRA-ARTICULAR DISEASE Anatomical bursae are common around synovial joints and may communicate with them. Bursae may RA is a systemic inflammatory connective tissue also develop in response to repeated trauma and, as disease. Occasionally, the disease will present with such, are named adventitious bursae. Adventitious systemic features, such as vasculitis or pulmonary bursae are commonly seen in the foot in people with nodules, with the joint inflammation developing as a RA. They may become periodically inflamed and late and often minor feature. Extra-articular features painful and they may develop secondary infection. are, as the name implies, clinical and pathological man- Bursae are often seen under the MTP joints (Boutry ifestations of the disease outside the synovial joints. et al. 2003), where the plantar fat pad is displaced and pressures are high, or, less commonly, over other sites A number of general observations can be made: of increased pressure, such as the posterior aspect of the calcaneus (Stiskal et al. 1997). It has also been ● They are often associated with inflammation in the demonstrated that local pressures are elevated under blood vessels, called vasculitis. metatarsophalangeal joints with greater joint degener- ation (Davys et al. 2004). ● The presence of extra-articular features is associ- ated with a worse prognosis in terms of mortality, Bursae may be relatively symptom free most of the although modern aggressive treatment with time, but may become inflamed periodically leading to intense discomfort on weight bearing. The treat- ments discussed in Chapter 6 include strategies to offload the area and aspiration; the latter relieves symptoms and permits infection to be excluded. Compressive and shearing forces acting on the skin can lead to corn and callus formation, and the pres- ence of scarring from surgical interventions will also increase the chances of the person with RA developing symptomatic callus (Fig. 3.2). Calluses usually become problematic only when the thickness of the callused plaque limits skin elasticity. Where cornified nuclei are involved in a callus, local areas of high pressure lead to more significant symptoms. Periodic reduction of

66 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS immunosuppressive regimes has made an impact on this. ● People with extra-articular features are usually older, male, have rheumatoid nodules and are seropositive. Extra-articular features in rheumatoid Figure 3.3 Small vessel digital arteries manifesting as nail arthritis fold infarcts. ● Rheumatoid arthritis can affect any organ in the ● Inflammation of venules and small arteries usually body manifest as a purpuric rash (Fig. 3.4) ● Extra-articular features are generally caused by ● Necrotizing arteritis of small- and medium-sized vasculitis arteries, which causes major organ damage and may lead to digital gangrene (Fig. 3.5) ● Patients with extra-articular features are usually male, seropositive and nodular ● Extra-articular features are associated with a worse prognosis and higher mortality Can we predict which patients will develop extra- articular features? The risk factors for severity dis- cussed in Chapter 1 (homozygosity for the shared epitope, rheumatoid factor, age, smoking, and social deprivation) are a guide only. We still have no clear evidence that targeting this group for more aggressive treatment reduces the complications or improves the mortality. The problems with extended longitudinal observational studies, let alone randomized controlled trials, have been noted in Chapter 1. Vasculitis and leg ulceration Figure 3.4 Inflammation of venules and small arteries usually manifests as a purpuric rash. Clinically, vasculitis is an uncommon finding, but like its counterpart, neuropathy, much of the disease is Figure 3.5 Necrotizing arteritis of small- and medium-sized probably sub-clinical. Post-mortem studies have arteries can lead to digital gangrene. found evidence of vasculitis in up to 14% of cases of RA, but clinically the prevalence is much less. Turesson and colleagues found a prevalence of extra- articular features of 1.8% annually, with approxi- mately one-third of these cases manifesting as cutaneous vasculitis (Turesson et al. 1999). In fact, vasculitis, neuropathy, and nodules are all part of the same pathological process with inflammation of blood vessels being the underlying lesion. (However, if nodularity is a defining feature of vasculitis, then it is clinically more common than generally believed.) Vasculitis may present clinically in one of three ways (for a full discussion see Breedveld (Breedveld FC 2003): ● Small vessel digital arteritis manifest as tiny nail fold infarcts (Fig. 3.3)

Clinical features of the foot in rheumatoid arthritis 67 It is important to note that each of these manifesta- – kidney: glomerulonephritis tions is not mutually exclusive and all three types may – bowel: mesenteric infarcts occur in the same patient, although this is uncommon. – nervous system: peripheral neuropathy (thought The first type, manifest as nail-fold infarcts, is most commonly seen with an overall clinical prevalence of by some authors to be the prime sign of an under- about 10%. Many patients develop nail-fold infarcts lying vasculitis. Schmid et al. found 59% of their and little other evidence of vasculitis and appear to cases of biopsy proven vasculitis had a neuro- come to no harm from these. Both of the other two pathy (Schmid et al. 1961). types of vasculitis may be associated with systemic dis- ease and carry a graver prognosis. For example, necro- Leg ulceration in RA is not uncommon and merits a tizing arteritis is a bad sign and is associated with a separate paragraph. It is estimated that 9% of rheuma- high mortality rate (25% to 45% mortality over 2 years). tology out-patients have a leg ulcer at any one time, the figure for in-patients being 0.6–8% (McRorie et al. 1994). Clinically, there are features often shared by those Leg ulceration in this situation is thought to be multi- who develop vasculitis and other extra-articular fea- factorial, but the relative weights of the individual tures of disease. These include a high titre of rheuma- factors are unknown. Certainly, in many cases there toid factor, the presence of rheumatoid nodules, the appears to be a vasculitic element and such patients older age groups, a higher percentage of males, fre- often share the same features as those with vasculitis quent treatment with corticosteroids, and those with elsewhere: older age, severe deforming disease, extremely destructive disease. Clinical features sug- seropositive and nodular. Treatment for vasculitis will gesting vasculitis include the following (Voskuyl et al. frequently result in healing of the ulcer. However, other 2003): factors are likely to be contributing (McRorie et al. 1994): ● Systemic features, such as weight loss, fever, ● Venous insufficiency. There are good theoretical malaise reasons why venous insufficiency is present, includ- ing immobility, decreased ankle movement due to ● Cutaneous features, such as a purpuric rash, nail- arthritis (thus impairing the venous pump action of fold infarcts, leg ulcers (often multiple with a sharply the calf muscles). McRorie and colleagues have demarcated punched out edge and often associated argued that 50–80% of patients with leg ulcers have with extreme pain see Fig. 3.6), and rheumatoid venous drainage problems (McRorie et al. 1998). nodules ● Macrovascular arterial disease. Using the ankle- ● Eye signs: scleritis and episcleritis brachial index 41% of patients with ulcers had an ● Major organ damage: index of less than 0.9, the threshold for arterial insufficiency. – heart: pericarditis, heart valve lesions – lungs: pulmonary fibrosis, pleurisy, pulmonary ● Some ulcers may start as pyoderma gangrenosum, the basis of which is probably vasculitic. These nodules lesions can be seen in a number of diseases: they often start as a painful nodule that quickly breaks down to produce a deep sloughy ulcer with under- mined edges. It is not known how chronic leg ulceration in RA relates to chronic ulceration on the foot, but it is possi- ble that similar factors are operative. However, with foot ulcers, there may be other important factors, foot deformity, areas of high pressure and neuropathy, for example, which are more akin to the risk factors for ulceration in diabetes mellitus. Figure 3.6 Vasulitic ulcers are often multiple with sharply Macrovascular disease demarcated punched out edges. In addition to the distinctive features caused by inflammation of the blood vessels in RA it is important to note that morbidity and mortality from macro- vascular arterial disease (atherosclerosis leading to cardiovascular, cerebrovascular and peripheral

68 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS vascular morbidity) is increased in RA (Symmons prevent an accurate assessment of muscle strength. et al. 1998, Doran et al. 2002, Mitchell et al. 1986). Thirdly, articular disease may mask neurological sen- sory signs: joint damage will affect joint proprio- There appear to be a number of reasons for this. ception and inflammatory oedema may prevent an Firstly, conventional risk factors for atherosclerosis are accurate assessment of vibration loss. increased in RA; these include hypercholesterolaemia, smoking, lack of exercise and use of corticosteroids. Another important point is that early studies were However, Alkaabi and colleagues have shown abnor- pre-occupied with the association of vasculitis and malities independent of traditional risk factors (Alkaabi neuropathy with the use of therapeutic steroids (Hart et al. 2003). Alkaabi et al. measured intimal wall thick- & Golding 1960). It now seems likely that this associa- ness by ultrasound, the ankle-brachial pressure index tion was not causal but resulted from the more fre- and an index of cardiovascular risk (the QT dispersion quent use of steroids in cases more likely to develop time from the electrocardiograph) finding all three extra-articular features: that is the more severe cases. abnormal compared to age and sex matched controls. At that time steroids had only been in use for about 10 years and their benefit and side-effect profile was still Secondly, the pathological mechanisms underlying emerging. Observational studies had noted the associ- atherosclerosis are very similar to RA with, in this ation of steroid use with the systemic complications of case, the arterial wall being the target organ. Thus, RA and authors quite rightly discussed the possible there is an inflammatory cell infiltrate, and cellular aetiological role of these drugs. proliferation with production of cytokines similar to those produced in RA (Kaplan & McClune 2003). A suggested scheme for classifying neuropathy in Conversely, treatment with disease-modifying drugs RA is as follows (Chamberlain & Bruckner 1970): such as methotrexate may have an anti-inflammatory and anti-atherosclerosis effect beyond their effect on ● Compression neuropathies the rheumatoid disease (Choi et al. 2002). ● Distal sensory neuropathy ● Severe fulminating sensorimotor polyneuropathy Thirdly, serum levels of homocysteine, high levels ● Mononeuritis and mononeuritis multiplex. of which have been associated with accelerated athero- sclerosis, are abnormally elevated in RA. Treatment The first two are much more common; the latter with methotrexate may exacerbate this, although folic two, while less commonly seen, carry a worse prog- acid, which is often used as a co-treatment with nosis. As already mentioned, Lanzillo and colleagues methotrexate, suppresses homocysteine levels. found 23/40 subjects without clinical symptoms of peripheral neuropathy had electrophysiological evi- For these reasons, all patients with RA should have dence of a mild sensorimotor peripheral neuropathy an assessment of their risk factors for atherosclerosis at (Lanzillo et al. 1998). Lanzillo et al. also found a fairly regular intervals and appropriate interventions made high prevalence of asymptomatic compression neuro- to reduce these factors where possible. pathy with 5/40 subjects having carpal tunnel syndrome. Other studies looking at compression neu- Neuropathy ropathies in the foot have found a high prevalence of asymptomatic tarsal tunnel syndrome in RA (Baylan From a clinical point of view neuropathy is uncom- et al. 1981). While these results remain unconfirmed mon but if looked for (by biopsy and targeted clini- they are consistent and indicate that many patients cal examination) appears to be present in up to half have asymptomatic neurological abnormalities associ- the cases (Lanzillo et al. 1998). Lanzillo and colleagues ated with their disease. examined 40 consecutive cases where clinical symp- toms of peripheral neuropathy were absent. Of these, Compression neuropathies 43% had absent vibration perception in the legs and fully 58% had a sensorimotor peripheral neuropathy Clinically, the commonest compression neuropathy in on electrophysiological testing. As with vasculitis, RA is carpal tunnel syndrome, due to compression of which underlies these two pathologies, there is an the median nerve at the wrist as it passes, along with appreciable sub-clinical spectrum of disease. the long flexor tendons and their sheaths, under the relatively tight retinaculum. Other compression neuro- It is important to note that clinical detection of pathies in the upper limb are, in decreasing order of peripheral neuropathy may not be straightforward in frequency, lesions of the ulnar nerve, as it courses RA. Firstly, pain may arise from a number of different through the cubital tunnel at the elbow and the poste- tissues and from a number of different mechanisms: it rior interosseous nerve, as it pierces the fascia of the is sometimes hard for the patient and the clinician to supinator muscle just distal to the lateral epicondyle of distinguish a new onset neuropathic pain from an the elbow. existing articular pain. Secondly, articular pain will

Clinical features of the foot in rheumatoid arthritis 69 In the lower limb, more importantly for this book, the tively and if this syndrome is suspected clinically the following entrapment syndromes are of importance: patient should be referred for nerve conduction tests. ● Entrapment of the tibial nerve as it passes through the tarsal tunnel at the ankle Lesions of the common peroneal nerve, while not strictly relating to the foot and ankle, are mentioned ● Lesions of the common peroneal nerve at the knee here because they may result in foot drop. The com- which may result in foot drop mon peroneal nerve is vulnerable to entrapment as it winds around the head of the fibula at the knee. The ● Compression of the deep peroneal nerve under the commonest cause is trauma: plaster casts, operations extensor retinaculum at the ankle and pressure from the other leg, giving rise to the other name for this condition (‘crossed legs’ palsy). In ● Mortons’ interdigital ‘neuroma’. RA it may be compressed by a ganglion, rheumatoid nodule, an extension of synovial hypertrophy from the Five sensory nerves innervate the foot: the sural, knee or even a large knee osteophyte. the superficial peroneal, the deep peroneal, the lateral and medial plantar (both arising from the tibial nerve). Compression of the deep peroneal nerve is unusual Potential causes of entrapment include compression clinically, but there are no systematic studies of this from proliferative synovitis or tenosynovitis, rheuma- problem using electrophysiology, so the actual preva- toid nodules or bony deformity. In practice, the only lence in rheumatoid arthritis is unknown. The nerve significant problems occur due to tarsal tunnel syn- is vulnerable to compression as it passes under the drome and Morton’s neuroma as the other nerves are extensor retinaculum and, certainly, hypertrophic seldom in a position to be compromised by the above tenosynovitis in this location is frequently seen. The factors. clinical effects are painful hyperaesthesiae in the space between the first and second toes and weakness of By far the most important of these is the so-called extensor hallucis brevis (the strength of this muscle ‘tarsal tunnel syndrome’. The tarsal tunnel lies on must be tested with the ankle in full dorsiflexion to the medial side of the ankle and is bounded by negate the effects of the long extensor tendon to the the calcaneus, the flexor retinaculum (ligamentum great toe). lacinatum) and the tendinous arch of abductor hal- lucis (Pecina et al. 2001). Also found passing through A Morton’s ‘neuroma’ is a common early presen- the ‘tunnel’ are the posterior tibial artery and the tation of RA. As mentioned in the section on tendons of tibialis posterior and flexor hallucis ‘Synovitis and the foot’ in this chapter, the pathology longus. Tenosynovitis in the sheaths of the latter is is not of a neuroma of the inter-digital nerve, but the most likely cause of this problem in RA. As more often is a synovitis and bulging of the capsule already noted, the syndrome may be more common of the adjacent metatarsophalangeal joint or, in later than clinically indicated, if electrophysiological stages, a rheumatoid nodule (Awerbuch et al. 1982). studies are used as the ‘gold standard’. McGuigan The name has stuck and the clinical manifestation is and colleagues found a relatively high point preva- similar, but it is unfortunate that the original pathol- lence of 13% (McGuigan et al. 1983), while a preva- ogy described by Morton is not seen in these other lence of 25% was found by Baylan et al. (1981). Of conditions. importance in the latter study was the lack of rela- tionship between several other variables (including Distal sensory neuropathy symptoms, duration of disease, severity of disease, treatment, and age) and the presence of tarsal tunnel Like the entrapment neuropathies distal sensory neu- syndrome, a similar finding to that of Chamberlain ropathy is found more frequently on electrophysio- (Chamberlain & Bruckner 1970). It could be argued logical testing than it is clinically. When it is clinically from these studies that the syndrome is of no clinical evident it often presents with an unpleasant burning significance, but without a systematic study compar- sensation in the feet. It is often symmetrical and affects ing those with and without the syndrome and fol- the feet more than the hands. There is a higher pro- lowing cases prospectively this statement cannot be portion of male patients. Clinical findings include loss justified. Clinical symptoms include pain and paraes- of vibration sense and light touch at the foot and thesiae on the plantar aspect of the foot, more so on sometimes loss of ankle reflexes. Biopsy of peripheral the medial side. The pain may be confused with that nerves and/or muscle biopsy may reveal vasculitis arising from the joints and the paraesthesiae as com- (Chamberlain & Bruckner 1970, Hart & Golding 1960). ing from a more proximal location (such as the back). There is a poor prognosis generally; in one series sur- Like carpal tunnel syndrome, symptoms may be vival was 57% at 5 years (Peuchal et al. 1995). Voskuyl worse at night. Usually there is little to find objec- reported that a peripheral neuropathy was one of the

70 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS main distinguishing features for rheumatoid vasculitis ture, a multifocal neuropathy or a decreased serum (Voskuyl et al. 2003). complement (Peuchal et al. 1995). Severe fulminating sensorimotor polyneuropathy Sub-cutaneous nodules This is the less common variety of peripheral neuro- Rheumatoid nodules have been found to affect pathy usually carrying a worse prognosis. It is often between 17 and 34% of patients with RA (Turesson associated with severe pre-existing disability, male et al. 1999). When present they are an important clini- predominance, erosive seropositive disease, and often cal marker of rheumatoid disease, helping differenti- presenting dramatically with palsy, such as a foot ate RA from other causes of inflammatory arthritis. drop, and carrying a poor prognosis (Chamberlain & They may, on occasions, occur before the development Bruckner 1970). In one series of selected patients, all of arthritis, both in a subcutaneous distribution and in those with a distal sensorimotor peripheral neuropa- the lungs. Nodules on the feet are a possible risk fac- thy died with visceral ischaemia (Pallis & Scott 1965). tor for ulceration as they have the potential to increase pressure and friction from footwear as well as affect- Mononeuritis and mononeuritis multiplex ing local tissue viability. In terms of severity a mononeuropathy or a mono- The initial event in the formation of a rheumatoid neuritis multiplex are of grave prognostic importance, nodule is vasculitis. Possibly trauma has a part to play, mainly because they signal arteritis of medium-sized as the traditional sites for rheumatoid nodules are arteries and usually major organ involvement. over bony prominences and areas of repeated abrasion Clinically, there is often a sudden onset of nerve palsy. such as the elbow, knuckles or heel pad. Histologically, Typically, the patient will present with a foot drop, rheumatoid nodules initially comprise vascular gran- sometimes unnoticed, or a wrist drop (radial nerve ulation tissue that undergoes involution until it forms palsy). There will be a preceding history of weight loss a central area of necrosis, bordered by a palisade of and the other typical features of extra-articular disease radially arranged elongated cells and encapsulated will be found. Digital gangrene may occur. In fact in scar tissue. In keeping with other extra-articular Voskuyl found that the more the extra-articular fea- manifestations of disease, nodules are associated with tures the more likely the patient had a systemic vas- more severe, seropositive disease in males and are, culitis, including major organ involvement (Voskuyl therefore, considered to be a poor prognostic marker. et al. 2003). The feared complication of medium-vessel arteritis is mesenteric artery obstruction and necrosis Nodules tend to occur over bony prominences of a segment of bowel. It is feared, because it may where the skin and subcutaneous tissues are already present late, after the bowel has perforated, with the under increased stress. They vary in size and number patient septicaemic and in shock. Unfortunately, as and may persist indefinitely or can regress at the time. most of these patients are already on systemic steroids Common sites in the foot include the Achilles tendon the classical symptoms and signs are often masked (Fig. 3.7), over the first and fifth metatarsal heads and until the problem is well advanced. the heel pad, where they can be particularly trouble- some to the patient. Treatment with methotrexate can, Along with the medium-vessel arteritis, a small- paradoxically, make nodulosis worse increasing the vessel vasculitis results in the other major organ number and the prominence of the nodules. On occa- damage: pericardial and cardiac involvement, renal sions this is a reason for treatment discontinuation. and pulmonary involvement. Slowly progressive pulmonary fibrosis unresponsive to the usual treat- Figure 3.7 Rheumatoid nodules in the Achilles tendon. ments is also a grave prognostic sign. The patient already severely disabled by RA deformities who develops progressive pulmonary fibrosis and who, at each clinic appointment, is more and more breath- less, is a distressing sight in the face of our therapeu- tic impotence. In the series of Peuchal fully 23 of 32 cases with biopsy proven vasculitis had evidence of a major nerve involvement, and 38% of patients had cuta- neous lesions: these included purpura, ulcers, nail- fold infarcts, livedo reticularis and gangrene. Factors predicting decreased survival were a cutaneous fea-

Clinical features of the foot in rheumatoid arthritis 71 Hyperviscosity syndrome anatomical cross-sectional area, Helliwell found a sig- nificant reduction in RA: forearm muscle cross-sec- The viscosity of whole blood is a function of the tional area in RA 25.9 cm2 and in normals 29.7cm2 plasma viscosity and the cellular content, the red and (Helliwell & Jackson 1994). Although this difference white blood cells and the platelets. The viscosity of appears minimal in terms of force generation by the plasma is largely influenced by the protein content: forearm muscles it is a considerable reduction. the quantity and the quality of protein in terms of the size of the molecules and their shape. In conditions Secondly, the inflammatory process of RA may where excess protein is produced the serum viscosity affect the muscles directly thereby reducing the effec- may rise to the point where this hyperviscosity pro- tive force generation. The likely mechanism for this is duces clinical and pathological effects. This syndrome vasculitis, although drugs used in RA (in particular usually occurs in situations where large amounts of steroids) may contribute. Steinberg and Wynn-Parry immunoglobulin are produced, such as Waldenstroms found electromyographic evidence of muscle inflam- macroglobulinaemia or multiple myeloma where mation in 85% of their subjects (Steinberg & Wynn- excess light and heavy chain proteins occur (Pruzanski Parry 1961). & Watt 1972). The plasma viscosity can rise from a nor- mal value of under 2 to over 10. The plasma viscosity Thirdly, joint inflammation and deformity may con- is sometimes used as an indicator of inflammation as tribute to weakness as a result of afferent impulses it is influenced by acute-phase proteins. It can, there- from joint mechanoreceptors and nociceptors; a phe- fore, be markedly elevated in RA, usually in associa- nomenon known as arthrogenous muscle inhibition. tion with the production of large amounts of The same mechanism is responsible for the sudden rheumatoid factor. The clinical syndrome does not giving way of the knee and ankle when someone usually occur unless the plasma viscosity is 4 or over. treads on a sharp nail. People with inflamed foot and ankle joints must fight to overcome this reflex with Clinically, this syndrome may manifest in the fol- every step. A further electromyographic study found lowing way: surface abnormalities of the EMG signal, consistent with this mechanism, in 65% of cases with RA ● Neurological symptoms and signs. Dizziness, (Lenman & Potter 1966). headaches, lethargy, confusion and weakness. Enlarged, ‘sausage like’ veins may be visible in the Fourthly, deformity of joints may disrupt the nor- retina, sometimes with haemorrhages and exudates mal mechanical architecture that allows purposeful movement at the joint. Inflammation and attrition of ● Haematological. Patients may present with abnor- tendons will also contribute to these ‘biomechanical’ mal bleeding, purpura, bruising on the legs and factors. These mechanisms are readily observable in feet, and epistaxis. the ankle of someone with longstanding RA, particu- larly if a prominent pes plano-valgus deformity is ● The bleeding disorder may also be manifest in the present. gastro-intestinal tract with bleeding gums and rectal bleeding. There is no doubt that people with RA are weaker than their non-affected counterparts and fatigue more Treatment to reduce the production of excess pro- easily (Helliwell et al. 1988a). Significant muscle wast- tein, in RA, is aimed at the immune cells producing ing occurs, but there are also doubts about the quality immunoglobulin, the B lymphocytes. Treatment of of the muscle itself and the contribution of arthro- this condition is, therefore, with immunosuppressive genous muscle inhibition. In the study by Helliwell a drugs. Sometimes, in severe cases, the excess protein is multiple regression model incorporating an index of removed by plasmapheresis. joint pain and deformity found that both these vari- ables, in addition to muscle wasting, contributed sig- Muscle disease nificantly to the weakness but the model as a whole only accounted for 38% of the variation in grip Although pain and stiffness are the main symptoms of strength (Helliwell & Jackson 1994). Muscle biopsy RA, they are closely followed by weakness, particu- studies in selected subjects have confirmed a relatively larly of grip strength. There are several reasons for this. high prevalence of myositis, but have found, in addi- tion, evidence of neuropathy in 26% of cases (Haslock Firstly, patients often complain that their limbs et al. 1970). The problem is, therefore, clearly multifac- seem to have lost bulk since the beginning of their torial and in rehabilitation terms must be addressed disease. It has, however, been remarkably difficult to as a multidisciplinary problem if improvements are to demonstrate this with appropriately matched control be made. subjects. Using a validated method for measuring

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74 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Pruzanski W and Watt JG Serum viscosity and female rheumatoid outpatients. British Journal of hyperviscosity syndromes. Annals of Internal Medicine Rheumatology 1991; 30(4): 298–300. 1972; 7: 853–860. Turesson C, Jacobsson L and Bergstrom U Extra–articular rheumatoid arthritis: prevalence and mortality. Puechal X, Said G, Hilliquin P, Coste J, Job-Deslandre C, Rheumatology 1999; 38: 668–674. Lacroix C and Menkes CJ Peripheral neuropathy with Turner DWJ, Woodburn J, Helliwell PS, Cornwall MW, necrotising vasculitis in rheumatoid arthritis. Arthritis Emery P Pes planovalgus in RA: a descriptive and and Rheumatism 1995; 38(11): 1618–1629. analytical study of foot function determined by gait analysis. Musculoskeletal Care 2003; 1(1): 21–33. Puolakka K, Kautiainen H, Mottonen T et al. Impact of Vainio K The rheumatoid foot. A clinical study with initial aggressive drug treatment with a combination of pathological and roentgenological comments. Clinical disease-modifying antirheumatic drugs on the Orthopaedics & Related Research 1991; 265: 4–8. development of work disability in early rheumatoid van der Heijde DM, van t Hof MA, van Riel PL et al. arthritis: a five-year randomized followup trial. Arthritis Judging disease activity in clinical practice in & Rheumatism 2004; 50(1): 55–62. rheumatoid arthritis: first step in the development of a disease activity score. Annals of the Rheumatic Diseases Ropes MW, Bennett GA, Cobb S, Jacob T and Jessar RA 1990; 49(11): 916–920. 1958 revision of diagnostic criteria for rheumatoid Voskuyl AE, Hazes JMW, Zwinderman AH, Paleolog EM, arthritis. Arthritis and Rheumatism 1959; 2: 16–20. van der Meer FJM, Daha MR and Breedveld FC Diagnostic strategy for the assessment of rheumatoid Schmid FR, Cooper NS, Ziff M and McEwen C Arteritis in vasculitis. Annals of the Rheumatic Diseases 2003; 62(5): rheumatoid arthritis. American Journal of Medicine 1961; 407–413. 30: 56–83. Wells GA, Tugwell P, Kraag GR, Baker PR, Groh J and Redelmeier DA Minimum important difference between Scott DL, Pugner K, Kaarela K, Doyle DV, Woolf A, Holmes patients with rheumatoid arthritis: the patients J and Hieke K The links between joint damage and perspective. Journal of Rheumatology 1993; 20(3): 557–560. disability in rheumatoid arthritis. Rheumatology 2000; Whalley D, McKenna SP, de Jong Z and van der Heijde D 39(2): 122–132. Quality of life in rheumatoid arthritis. British Journal of Rheumatology 1997; 36(8): 884–888. Sokka T, Krishnan E, Hakkinen A and Hannonen P Wickman AM, Pinzur MS, Kadanoff R and Juknelis D Functional disability in rheumatoid arthritis patients Health-related quality of life for patients with compared with a community population in Finland. rheumatoid arthritis foot involvement. Foot & Ankle Arthritis & Rheumatism 2003; 48(1): 59–63. International 2004; 25(1): 19–26. Williams A and Meacher K Shoes in the cupboard: the fate Steinberg VL and Wynn-Parry CB Electromyographic of prescribed footwear? Prosthetics and Orthotics changes in rheumatoid arthritis. British Medical Journal International 2001; 25: 53–59. 1961; 1: 630–632. Woodburn J, Helliwell PS and Barker S Three dimensional kinematics at the ankle joint complex in rheumatoid Stiskal M, Szolar DH, Stenzel I, Steiner E, Mesaric P, arthritis patients with a painful valgus deformity of the Czembirek H and Preidler KW Magnetic resonance rearfoot. Rheumatology 2002; 41(12): 1406–1412. imaging of Achilles tendon in patients with rheumatoid Wright V, Dowson D and Longfield MD Joint stiffness – its arthritis. Investigative Radiology 1997; 32(10): 602–608. characterisation and significance. Biomedical Engineering 1969; 4: 8–14. Swann AC and Seedhom BB The stiffness of normal Wright V and Moll JMH Seronegative Polyarthritis. North articular cartilage and the predominant acting stress Holland Publishing Co, Amsterdam, 1976. levels: implications for the aetiology of osteoarthrosis. Yelin E, Henke C and Epstein W The work dynamics of the British Journal of Rheumatology 1993; 32: 16–25. person with rheumatoid arthritis. Arthritis & Rheumatism 1987; 30(5): 507–512. Symmons DP, Bankhead CR, Harrison BJ, Brennan P, Barrett Yelin E, Meenan R, Nevitt M and Epstein W Work disability EM, Scott DG and Silman AJ Blood transfusion, smoking, in rheumatoid arthritis: effects of disease, social, and work and obesity as risk factors for the development of factors. Annals of Internal Medicine 1980; 93(4): 551–556. rheumatoid arthritis: results from a primary care-based incident case–control study in Norfolk, England. Arthritis & Rheumatism 1997; 40(11): 1955–1961. Symmons DPM, Jones MA, Scott DL and Prior P Long term mortality outcome in patients with rheumatoid arthritis: early presenters continue to do well. Journal of Rheumatology 1998; S25(6): 1072–1077. Thompson PW and Pegley FS A comparison of disability measured by the Stanford Health Assessment Questionnaire disability scales (HAQ) in male and

Color Plate 3.3 Small vessel digital arteries manifesting as nail fold infarcts. Color Plate 3.6 Vasulitic ulcers are often multiple with sharply demarcated punched out edges. Color Plate 3.4 Inflammation of venules and small arteries Color Plate 3.7 Rheumatoid nodules in the Achilles tendon. usually manifests as a purpuric rash.

75 Chapter 4 Clinical assessment CHAPTER STRUCTURE SCREENING TOOLS Screening tools 75 There is no standardized method by which to assess Monitoring progression of the disease 77 the musculoskeletal system. Assessment of this nature Assessing disease activity in the foot 78 is often perceived to be very difficult and time con- General principles of assessment of impairment suming by students and health professionals and there is evidence of neglect of musculoskeletal examination in the foot 82 in clinical practice (Doherty et al. 1990). In an attempt Vascular assessment 94 to overcome lack of standardization, a simple screen- Neurological assessment 95 ing tool (GALS – Gait, Arms, Legs and Spine) was Summary 96 developed and has found widespread acceptance (http//www.arc.org.uk) (Doherty & Doherty 1992). The screening consists of asking the patient three questions: (1) Do you have any pain or stiffness in your muscles, joints or back? (2) Can you dress your- self completely without any help? (3) Can you walk up and down the stairs without any help? This is followed by a brief structured examination of the patient’s gait, arms, legs and spine (Table 4.1). GALS is a short, simple, standardized history and examination of the locomotor system, which has been shown to be useful for the detection of joint abnormalities. However, it is not a substitute for a more detailed examination. GALS allows identification of abnormal- ity to a specific region, which should then be subject to a more detailed regional examination. Recently, a set of core regional examination skills for medical students has been developed (Regional Examination of the Musculoskeletal System [REMS]). These core skills have been developed by national con- sensus (Coady et al. 2004). Initially, focus groups of rheumatologists, orthopaedic surgeons, geriatricians and general practitioners were used to inform the con- tent of a national questionnaire. Questionnaires were sent to 3373 doctors, in which they were asked to assign a value to each regional musculoskeletal clinical skill using a five-point Likert scale ranging from ‘definitely

76 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Table 4.1 Summary of GALS (Doherty et al. 1992). The core set of musculoskeletal examination skills for the feet identified by REMS Gait Symmetry and smoothness of movement Normal stride length Examine sole of patient’s feet Ability to turn normally Recognize hallux valgus, claw and hammer toes Assess a patient’s feet with them standing Arms Assess wrist/finger swelling deformity Assess for flat feet (including patient standing on Hands Squeeze across 2nd to 5th metacarpals Inspect hands for muscle wasting tiptoe) Grip strength Assess normal pronation/supination Recognize hind foot/heel pathologies Elbows Assess plantar and dorsi-flexion of the ankle Shoulders of forearm Assess movements of inversion and eversion of the Assess power grip (make a tight fist) Assess precision grip (put fingers on foot Assess the sub-talar joint thumb) Perform a lateral squeeze across the metatarso- Can patient fully extend at the elbow phalangeal joints (arms out straight) Assess flexion/extension of the big toe Can patient place their hands behind their Examine a patient’s footwear. head individual clinical tests did not appear to influence the decision of clinicians in accepting it as ‘core’ for stu- Legs Assess for knee swelling and deformity dents. It is also not surprising that the survey also Knees Assess for quadriceps muscle bulk showed consistently that examination of the feet was Assess for knee effusion one of the least popular techniques. This finding is not Hips Assess for crepitus during knee flexion exclusive to musculoskeletal examinations and is con- Feet Assess internal and external rotation sistent with evidence of low rates of foot examination Squeeze across metatarsal for in other disciplines such as diabetes mellitus. Examination of the foot has been shown to be one of tenderness the most effective mechanisms for preventing diabetic Check for callosities foot complications. However, it remains the most neg- lected part of the diabetic assessment (Levin 2001). Spine Low rates of foot examination have been reported dur- ing out-patient and in-patient consultations (Wylie- Assess from Scoliosis Rosett et al. 1995). behind for Symmetrical muscle bulk Whilst GALS and REMS are a useful starting point for examination of the foot in a patient with RA, the Level iliac crests assessment is aimed at a broad group of patients and is not specific to patients with RA. As RA is a hetero- No popliteal swelling geneous disease, it is not possible to develop a gold standard for assessment. However, given the likely Normal hindfoot alignment sites of involvement (outlined in Chapter 3) it is possi- ble to examine these sites using a structured and sys- Palpate for Tenderness over mid-supraspinatus tematic approach. Generally, there is a lack of ‘gold Assess from Kyphosis jstandard’ diagnostic tests. Despite the poor sensi- tivity and specificity of many of the examination tests, the side for Flexion (can you touch your toes) they are included for the purposes of completeness. It is hoped that future research will address this issue. Assess from Assess lateral flexion at the neck As with any assessment of a patient, taking a the front (can you touch your shoulder with patient history is essential. Full descriptions of successful strategies used in gathering patient history your ear) not required’ to ‘essential’. Findings from the focus groups and national survey were assessed using a group nominative technique with national representation from the above-listed specialties. This resulted in the identifi- cation of 50 core regional musculoskeletal examination skills deemed to be appropriate for medical students. The results are available in handbook and DVD format through the ARC (http//www.arc.org.uk). It is interesting to note that the national question- naire showed that the sensitivity and specificity of

Clinical assessment 77 (non-verbal communication, environmental factors, Useful prompts for history taking—cont’d etc.) have been described in detail elsewhere (Bickley & Szilagyi 2003). It is important to determine what FOOT HISTORY has brought the patient to the consultation, the pat- 1. How does your arthritis affect your feet? tern of distribution and chronological development 2. Has it always affected your feet? of symptoms, the impact of the problem and the 3. As your arthritis progressed, tell me how it has patient’s concerns and expectations. Our clinical experience at Leeds suggests that many patients do affected your feet over time? not know why they have been referred to the podia- 4. Using your hands, can you show me exactly where trists and generally have a low expectation for treatment. For the purposes of this chapter, some sug- you get the problems you have described? gestions of prompts, which are particularly useful 5. In what way does the arthritis in your feet impact when taking a history in a patient with RA foot prob- lems, are outlined below. on your life? 6. How are your feet in comparison to other joints, such as your knees or hand joints? Useful prompts for history taking MONITORING PROGRESSION OF THE DISEASE HISTORY 1. When did your arthritis first start? Assessing functional limitation and participation 2. How did it start? restriction are addressed in the Chapter on Outcome 3. What made you seek help? Evaluation (Chapter 8). 4. How was the diagnosis made? 5. You have had your arthritis now for ___ years, tell The core set of data collected in RA comprises of: tender and swollen joint counts, pain assessment, me how it has developed over that time? patient and physician global assessment and an acute 6. How has your arthritis been this week (is it active phase marker such as the ESR or CRP. The assessment is completed by the patient to ascertain functional lim- or quiet?) itation. These items will be discussed in more detail in 7. How is your arthritis today (in comparison with Chapter 8. when it’s at its best and when it’s at its worst)? Assessment of pain TREATMENT HISTORY By far the most common reason for referral to rheuma- 1. What treatment are you currently receiving for tology departments is pain. Foot pain is the most com- mon reason for referral to podiatry. Pain is a complex, your arthritis (in terms of medicines, tablets, pills subjective sensation and difficulties arise when one or injections)? attempts to define, explain or measure it. There has 2. How do you take these treatments (self or at been some suggestion in the literature that there are clinic)? gender and disease differences in pain thresholds and 3. What treatments have you had in the past? that patients with RA may have lower pain thresholds 4. What do you feel has been the most effective than, for example, ankylosing spondylitis (Buskila treatment and why? et al. 1992, Gerecz-Simon et al. 1989, Huskisson & Dudley Hart 1972, Walker & Carmody 1998). OTHER HISTORY 1. Some people with your type of arthritis have other Discordance of pain with tender and swollen joint counts is often apparent during clinical examination problems, for example chest problems. Do you and is highlighted in the summary of clinical data know if you have any of these? shown in Figure 4.1. The number of tender, swollen and 2. Do you go to see any other medical person because patient reported painful joints in the feet was recorded of problems with your arthritis (for example some in 40 consecutive patients with RA with varying disease people go to the chest clinic, others to the eye duration and disease activity. Most patients reported far clinic) less painful joints than actually were found to be either 3. Have you had any special investigations for your tender or swollen during examination. arthritis? Continued

78 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS Score (0−14) 14 pain is often helpful in determining the structures 12 involved (for example, aching suggests pain within 10 the joint, whereas, burning, tingling, stabling, radiat- ing suggests neurological elements). The presence or 8 absence of pain during different activities can also be 6 helpful. 4 2 ASSESSING DISEASE ACTIVITY 0 IN THE FOOT Painful Swollen Tender It is essential to be able to distinguish if lower limb pain and functional limitation is related primarily to Figure 4.1 Painful, swollen and tender joint counts. biomechanical dysfunction or related to increased dis- ease activity, or a combination of the two. Objective There are many outcome tools that can be used in measurements should be taken during routine clinical clinical practice to establish the extent of foot pain and practice, to determine the activity level of the RA. It is the resultant functional limitation and activity restric- important to take measures of disease activity as part tion. Some are specifically validated for the use in RA of routine practice to: and others aimed at community-based populations. These are described in detail in Chapter 8. A useful ● monitor the patient over time strategy, which helps to determine nature and sites of ● predict further outcome involvement, is to ask the patient to complete a lower ● assess change over time as an effect of systemic and limb map. This helps the patient focus on their symp- toms and can provide useful clues as to the possible local treatments aetiology of the underlying problem (see Fig. 4.2). Pain ● make decisions on treatment change. in small joints tends to be more accurately localized by patients than pain in larger joints. The character of Studies have shown that patients attending early inflammatory arthritis clinics may have evidence of bone erosions (Harrison & Symmons 2000, Machold et al. 2002). This suggests that damage related to dis- ease activity can occur in a relatively short time frame. Therefore, it is important that practitioners assess patients on every visit for indicators of increased disease activity and take appropriate action. Figure 4.2 This patient was referred to the podiatry department with persistent medial ankle pain. She had been diagnosed with rheumatoid arthritis for 18 months and her disease activity was generally low. A copy of her completed foot map can be seen above. The photograph shows obvious swelling along the muscle tendon of tibialis posterior. The area was painful and felt warm and ‘boggy’ on palpation. The patient has a low medial arch profile and failure of the calcaneus to invert when standing on tiptoe. High-resolution ultrasound scanning showed tibialis posterior tenosynovitis. Provision of functional orthoses along with an ultrasound guided corticosteroid injection fully resolved the tenosynovitis.

Clinical assessment 79 Determining the number of tender and swollen swollen and painful foot joints can be recorded; a joints is a key component in the clinical assessment of suggested format is shown in Figure 4.4. RA to monitor disease status and to assess treatment response. There is a strong relationship between Painful joints disease activity, structural damage and functional disability. Patient self-reported joint pain, and perceived disease activity can be helpful in clinical assessment; however, A number of different joint scoring systems are there is debate whether these measures are reliable and available and there is not complete agreement on valid (Houssien et al. 1999, Stewart et al. 1993, Stucki which joints should be evaluated. Two methods (the et al. 1995). Agreement between physician and patient 66/68 and the 28 joint counts) are widely used in clin- derived scores of disease activity are sufficient to allow ical practice. The 28 joint count is simpler to perform patients’ derived scores to be used in clinical research, and takes less time and is reported to be comparable although physician and patient scoring systems are not with the 66/68 joint count in terms of the value of the directly interchangeable (Houssien et al. 1999). information it provides and reproducibility (Smolen et al. 1995). The main difference between the two Asking patients to describe the character of pain is scoring methods is that the 28 joint count excludes helpful in understanding the underlying cause. The the joints of the feet and ankles so that potentially presence or absence of pain during specific activities relevant clinical information about the feet is not can also provide useful clues. Many common lower recorded. limb pathologies have common patterns of foot pain. It is important to recognize these patterns; for exam- Considerable variation between observers in the ple, plantar heel pain on first weight bearing, which is assessment of tender and swollen joint counts has relieved initially by walking and then is made worse been highlighted in the literature. Scott et al. (1996) by standing and walking is the classical feature of investigated the extent of variation between different plantar fasciitis. examiners (medical and nursing practitioners) in the measurement of joint swelling and tenderness, based Swelling on the 28 joint count. A high coefficient of variation between examiners performing the 28 joint count Joint swelling can be either due to soft tissues or bony was reported (up to a maximum of 204%). The study proliferation. When performing swollen joint counts, also highlighted the importance of training and only swelling of the soft tissues should be included; standardization. After training, the mean coefficient swelling associated with osteophytic proliferation or of variation for tender and swollen joints had deformity is not included. Swelling is usually improved, but was still high, at 65% and 59% respec- detectable along the joint margins and is usually con- tively (Scott et al. 1996). fined to a discrete area and conforms to an underlying anatomical structure. It is often hard to distinguish DAS (Disease Activity Score) 28 can be determined between swelling due to joint effusion, synovitis or with the number of tender and swollen joints (based on inflammation of periarticular structures. There is evi- the 28 joint score), with a measure of patient’s global dence of greater sensitivity of imaging modalities in assessment (on a 100 mm visual analogue scale) and the detection of synovitis, tenosynovitis and tendon with an acute phase reactant, usually the ESR or CRP tears: synovitis in the foot, in particular, is detected at (Fig. 4.3). Values have been established and can deter- the MTP joints more often with ultrasound than by mine if a patient is in a flare or not. A full description clinical examination (Karim et al. 2001). can be found in Chapter 8. The DAS 28 is endorsed by EULAR and has been used more widely to direct deci- Tenderness sions on systemic management. Joint tenderness is pain in a joint under defined cir- Allied health practitioners working in primary care cumstances. These include pain at rest with pressure teams or distant sites may not easily have access to (for example, at the metatarsophalangeal (MTP) laboratory reports that include details on acute-phase joints) or pain on movement of the joint. The pres- reactants. If it is not possible to access blood results, sure used to elicit joint tenderness should be exerted the number of tender, swollen and painful joints can by the examiner’s thumb and index finger, which is act as a reflective marker of disease activity (greater sufficient to cause ‘whitening’ of the examiner’s nail number of swollen, tender and painful joints relate to bed. Different techniques can be used to elicit joint increased disease activity). The number of tender, tenderness, either a two- or four-finger technique. swollen and painful joints can be serially plotted over time to monitor disease progression as can the number of joints with deformity. The number of tender,

80 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS DAS 28 Number Tender joint count The number of swollen joints are counted as follows: 0 = not tender 1 = tender Tenderness will be assessed for 28 joints on both right and left side. The following joints will be evaluated: 10 proximal interphalangeal joints and 10 metacarpophalangeal joints, 2 wrists, 2 elbows, 2 shoulders and 2 knees. Tenderness will be elicited by firm pressure over the joint margin Swollen joint count The number of swollen joints are counted as follows: 0 = not swollen 1 = swollen Swelling will be evaluated by palpation, only soft tissue swelling will be accounted for. The same 28 joints as for tenderness will be assessed for swelling. Number ESR (mm/hr) Patient General Health Please mark on the line with a cross the response which best describes your general health in the last week Best possible health Worst possible health Score mm Figure 4.3 A proforma used for recording tender and swollen joint counts that may also be used for calculating the DAS28 score.

Clinical assessment 81 Painful Left Right Talo-Navic Ankle Ankle STJ Calc-Cub STJ Talo-Navic Calc-Cub MTPs MTPs IPJs IPJs 1 2345 1 2345 Total — /28 Tender Left Right Ankle Ankle STJ Calc-Cub STJ Talo-Navic Talo-Navic Calc-Cub MTPs MTPs IPJs IPJs 1 2345 1 2345 Total — /28 Swollen Left Right Talo-Navic Ankle 1 Ankle STJ Calc-Cub STJ MTPs Talo-Navic Calc-Cub IPJs 1 2345 MTPs IPJs 2345 Total — /28 Figure 4.4 Suggested tender and swollen joint count.

82 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS A full description of joint counts can be found in the Table 4.2 Outline for foot examination. EULAR handbook (http//www.eular.org). As consid- erable variation exists between examiners and tech- Examination Look for: niques it is recommended that the methods are of skin Necrosis standardized and, where possible, performed by the Ulceration same person. Examination Nodules of the nail Scarring (previous ulceration/trauma/ Joint stiffness Examination surgical) Joint stiffness is a complex sensation defined mechan- of the foot Corns/callus ically as increased resistance to movement of the joint. Haemorrhage into callus A fuller description can be found in Chapter 3. Joint Examination Skin infection (bacterial/fungal) stiffness is usually more pronounced following of footwear Blisters periods of inactivity or rest. Many clinicians will use Adventitious bursa formation the number of minutes of early morning stiffness, severity and number of joints affected as an objective (inflamed) measure of joint stiffness. Interdigital maceration/ulceration/corns Colour changes, venous, ischaemic, KEY POINTS vasospastic (pallor/rubor/cyanotic) ● Tender and swollen joint counts are useful in Oedema clinical practice to monitor disease activity. Thinning of the skin/bruising (associated ● Considerable variation exists between different with long-term steroid use) examiners. However, standardization of methods Evidence of poor foot hygeine and training greatly improve reliability. Feel for: ● In the absence of acute-phase reactants, serial Temperature changes recording of tender and swollen joint counts, Swelling pain and functional limitation can provide useful information on disease progression. Look for: Fungal nail infections ● EULAR standards provide full instructions on how Ingrowing toe nails to perform tender and swollen joint counts Splinter haemorrhages/nail fold infarcts (Copies can be obtained by contacting the pub- Evidence of poor self care/neglect lisher, Van Zuiden Communications, ISBN 90-751- 41-90-4.) It is best to have training from someone Look for: experienced in performing joint counts. Muscle bulk/posture Rearfoot deformity/swelling GENERAL PRINCIPLES OF ASSESSMENT Midfoot deformity/swelling OF IMPAIRMENT IN THE FOOT Collapse of medial longitudinal arch Forefoot deformity The key elements of a foot examination are look, feel Daylight sign and move. It is essential to have an appreciation of the Prominent metatarsal heads normal surface anatomy, muscle bulk, joint move- Hallux valgus ments and muscle power. Careful inspection should Lesser toe deformity be performed to identify abnormalities and inspection Bursitis/tendonitis undertaken in both weight bearing and non-weight bearing conditions from all aspects. A structured, sys- Feel for: tematic approach reduces the possibility of omitting Prominent metatarsal heads any structures. It is convenient to assess the foot as Tender, painful and swollen joints three units – the rearfoot, midfoot and forefoot. Assess muscle tendons for swelling Assessment procedures will be outlined around these three functional units. Table 4.2 summarizes the exam- and tenderness ination schedule. Assess joints for range of movement Assess muscle strength Look for: Assess fit of the shoe Assess appropriateness of shoe for function Excessive wear patterns Bulging of medial counter Fastenings Feel for: Midsole flexibility Forefoot cushioning

Clinical assessment 83 Look with RA (Platto et al. 1991). They defined an index of structural deformity for the forefoot, hindfoot and Joint deformity total foot. In the forefoot, scoring is based on the presence or absence of claw, hammer or cock toes; Joint deformity should be documented to allow presence of bunion or hallux valgus, exostosis at the assessment of progression of disease over time. An 5th MTP joint, and subluxation at the MTP joints. The estimation of the degree of deformity, whether the hindfoot score is dependent on the valgus or varus deformity is fixed or mobile and if it is correctable or position of the hindfoot, total passive range of non-correctable should also be included. Several scor- motion at the ankle (dorsi/plantarflexion) and pres- ing systems to document foot deformity are available ence or absence of pes planus or pes cavus deformity (generic and specific to RA), although they have failed (Table 4.3). to be investigated thoroughly in terms of reliability. In the absence of a validated foot deformity scoring The American Orthopedic Foot and Ankle Society system specifically developed for patients with RA, developed clinical rating score systems for the hind- the SI proposed by Platto is the preferred method to foot, midfoot and forefoot (the AOFAS clinical rating quickly quantify extent of foot deformity. However, it scores) (American Orthopedic Foot & Ankle Society must be recognized the SI has not been thoroughly 1994). These scoring systems have been utilized widely investigated in terms of reliability, and the dichoto- in the orthopaedic literature mainly as outcome meas- mous nature of scoring deformity, while improving ures following surgical interventions. There are four inter-examiner reliability, will limit its ability to - scoring systems for the Ankle-Hindfoot (AH), midfoot monitor subtle changes in foot posture/ (M), Hallux Metatarsophalangeal-Inter-Phalangeal deformity over time. (HMTP-IP) and the Lesser Metatarsophalangeal- Inter-Phalangeal (LMTP-IP). The AH and HMTP-IP Root and colleagues arbitrarily assigned stages scales have been used to evaluate ankle arthrodesis, (1–4) to the progression of hallux abductovalgus total ankle replacement, forefoot athrodesis or 1st MTP (HAV) deformity (Root et al. 1977). In stage 1, lateral resection in patients with RA (de Palmer et al. 2000, subluxation of the base of the proximal phalanx of Mulcahy et al. 2003, Nishikawa et al. 2004). The AH the hallux in relation to the 1st metatarsal head scale has been criticized for its inherent limited preci- occurs. This is not detectable by clinical examination sion, which is associated with the small number of and is only evident on X-ray. Stage 2 HAV is charac- response intervals available (Guyton 2001). terized by abduction deformity of the hallux. The hal- lux is seen to press against the second toe. In stage Platto and colleagues developed the Structural 3 there is development of metatarsus primus varus Index (SI) to quantify structural deformity in patients Table 4.3 Structural index as described by Platto et al. 1991. Structural indices for fore and hindfeet deformity (after Platto et al. 1991) Forefoot score Hindfoot score Deformity Right Left Deformity Right Left Hallux valgus (Yes=1, No=0) Calcaneal valgus/varus degrees (0–5=0; 6–10 = 1; 5th MTP Exostosis (Yes=1, No=0) 11–15 = 2; >15=3) Cock/hammer/claw toes present Ankle total ROM (46–60˚ = 0; (Number 0–5) 31–45˚ = 1; 15–30˚ = 2; <15˚ = 3) MTP subluxed (Number 0–5) Total Score (from 12) Pes planus/pes cavus (Yes = 1, No = 0) Total score (from 7) SI forefoot = right + left _____ /24 SI hindfoot = right + left _____ /14 Score [as ratio from 200] _____ /200 Score [as ratio from 200] _____ /200 Total foot deformity (forefoot + hindfoot) _____ /38 Score [as ratio from 200] _____ /200

84 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS (an abnormally large transverse plane angle between ● hallux (hallux valgus deformity, non-weight the 1st and 2nd metatarsals, which is detectable on bearing) visual inspection of the foot). Stage 4 is the most advanced stage in the progression of HAV, where dis- ● lesser toes (presence of deformity, non-weight location or subluxation of the hallux occurs. The hal- bearing). lux most frequently underrides the 2nd toe but in some cases can override the 2nd toe. Muscle Traditional classifications of lesser toe deformity Muscle may be involved as part of the process of RA (clawed, hammer, mallet) become increasing difficult (see Chapter 3). Joint pain and associated functional to ascertain in patients with the complex types of foot limitation may also contribute to disuse muscle atro- deformities seen with RA. The clinical approach at phy. Pain avoidance strategies adopted by patients Leeds uses a functional classification based on may result in weakness and wasting of specific muscle whether the lesser toes are weight bearing or non- groups. For example, weakness in the gastrocnemius weight bearing during gait. Anecdotal evidence and soleus muscles can develop in patients who fail to suggests this classification relates better to the pres- create the normal plantarflexion moment at the ankle ence/absence of metatarsal head pain, callus and high joint in terminal stance in an attempt to avoid pain plantar pressures. across painful MTP joints. A visual inspection of the lower leg for normal muscle bulk should be per- When assessing the forefoot it is also important to formed making note of any apparent loss in muscle check for splaying of the forefoot. Many patients bulk, hypertrophy or flexion contractures. A summary report they have to ‘go up a size’ in shoes to accom- of muscle testing in the foot is given in Figure 4.5. modate increased foot width. Daylight sign (when daylight can be observed between the toes, Fig. 3.4) is Assessment of the skin a clinical indicator of synovitis or inter-metatarsal mass at the relevant MTP joint. However, sensitivity Inspection of the foot from all aspects should be and specificity data for this clinical sign is lacking. undertaken for any pressure induced lesions (hyper- keratotic lesions, adventitious bursae), ulceration, Foot posture scarring or extra articular features of RA (including nodules and nail fold infarcts). At the posterior There are a number of different mechanisms by aspect of the calcanueus, check the tendo Achilles, which to classify foot posture ranging from visual retrocalcaneus and subcutaneous bursae for evi- inspection through to measurements of foot anthro- dence of inflammation and for evidence of skin irri- pometrics and radiographic evaluations. Each tation or hyperkeratotic tissue from a rigid heel method has particular merits and limitations that counter. On the plantar surface of the mid and fore- have been critically reviewed elsewhere (Menz 1998, foot check for any pressure induced lesions. Inspect Razeghi & Batt 2002). There is no general consensus the dorsal toes for evidence of irritation from on which measurements to use. Many reliability footwear and the interdigital areas for maceration, studies have been performed for various parameters infection, or any lesions. in healthy control subjects and one cannot assume equipoise in patients with RA. It is important to Footwear assess foot shape both non-weight bearing, standing and during gait. Although there is an assumption No examination of the foot in RA is complete without that foot morphology dictates function, literature an inspection of the footwear. A high proportion of suggests there is a poor relationship between meas- patients wear ill-fitting footwear. One study found ures of foot structure and foot function in asympto- that 24% of patients attending general medical outpa- matic individuals (Hamill et al. 1989, McPoil & tient appointments wore shoes that were the wrong Cornwall 1994, McPoil & Cornwall 1996). It is likely size (Reddy et al. 1989). In the elderly, the proportion that strategies for pain avoidance used in RA patients of people wearing ill-fitting shoes is higher. Burns and (for example minimally loading tender MTP joints) colleagues (2002) found 72% of patients on an elderly will further complicate the relationship foot structure general rehabilitation ward were wearing ill-fitting and function. shoes (a discrepancy in length of more than half a British shoe size or more than one British width fitting, Foot postural changes to screen for during visual 7 mm). The study found a significant association inspection should include: between incorrect shoe length and ulceration and self- reported foot pain. Patients with foot deformity find it ● alignment of the rearfoot (valgus or varus position) increasingly difficult to buy footwear that can accom- ● medial longitudinal arch profile (high, normal, low) modate their foot shape as deformity progresses.

Region Muscle & Technique Picture Posterior innervation Resistance Patient Stabilization Movement position Patient has to Triceps surae Supine Lower third of Under plantar plantarflex at the ankle (L5,S1,S2) leg surface of the foot against resistance Lateral Peroneus brevis Supine Lower third of Hand over the dorsal, Start position – foot in (L4,L5,S1) neutral position. leg, above lateral border of the Patient has to evert the foot against resistance malleolus forefoot. (demonstration of desired movement probably needed) Peroneus longus Supine Lower third of Hand over the dorsal, Start position – foot in (L4,L5,S1) dorsiflexed position. leg, above lateral border of the Patient has to evert the foot against resistance. malleolus forefoot. Figure 4.5 Summary of muscle testing. Clinical assessment 85

Region Muscle & Technique Picture 86 THE FOOT AND ANKLE IN RHEUMATOID ARTHRITIS innervation Resistance Patient Stabilization Movement position Tibialis anterior Supine Lower third of On dorsal surface of Patient has to (L4,L5,S1) leg the foot dorsiflex at the ankle Anterior against resistance Extensor hallucis Supine Metatarsus On dorsal aspect of Patient has to dorsiflex l ongus the proximal and the hallux against (L4,L5,S1) distal phalanx of the resistance hallux Extensor Supine Metatarsus On the sides of the Patient has to extend digitorum brevis proximal phalanges the lesser toes against & extensor resistance digitorum longus (L4,L5,S1) Figure 4.5 Cont’d

Region Muscle & Technique Picture innervation Patient Stabilization Resistance Movement position Tibialis posterior Supine Lower third of Hand over the dorsal, Start position – foot is (L4,L5,S1) leg just above Medial the malleolus medial surface of slightly plantarflexed. the foot at the level Patient has to invert of the metatarsal the foot against heads resistance (demonstration of desired movement probably needed) Flexor hallucis Supine Sides of the Plantar surface of Patient has to plantar- l ongus proximal distal phalanx of flex at the 1st (L5,S1,S2) phalanx of hallux interphalangeal joint hall ux against resistance Flexor digitorum Supine Sides of the Plantar surface of Patient has to plantar- l ongus intermediate distal phalanx of flex at the distal (L5,S1) phalanx of second toe interphalangeal joint second toe against resistance Clinical assessment 87 Figure 4.5 Cont’d