Foot Problems in Older People Assessment and Management

References 147 135. Pitei DL, Foster A, Edmonds M. The effect of 150. Kranke P, Bennett M, Roeckl-Wiedmann I et al. regular callus removal on foot pressures. Journal of Hyperbaric oxygen therapy for chronic wounds. Foot and Ankle Surgery 1999; 38: 251–255. Cochrane Database of Systematic Reviews 2004; 1: CD004123. 136. Pataky Z, Golay A, Faravel L et al. The impact of callosities on the magnitude and duration of plantar 151. TerHaar GR, Daniels S. Evidence for ultrasonically pressure in patients with diabetes mellitus. Diabetes induced cavitation in vivo. Physics in Medicine and and Metabolism 2002; 28: 356–361. Biology 1981; 26: 1145–1149. 137. Ovington L, Peirce B. Wound dressings: form, func- 152. Dyson M. Mechanisms involved in therapeutic ultra- tion, feasibility, and facts. In: Krasner DL, Rode- sound. Physiotherapy 1987; 73: 116–120. heaver GT, Sibbald RG, eds. Chronic wound care : a clinical source book for healthcare professionals, 153. Mortimer AJ, Dyson M. The effect of therapeutic 3rd ed. Wayne: HMP Communications; 2001: ultrasound on calcium uptake in fibroblasts. Ultra- 311–320. sound in Medicine and Biology 1988; 14: 499–506. 138. Turner TD. Control the environment to heal the wound. Chemist and Druggist 1985; 2: 438–444. 154. Flemming K, Cullum N. Therapeutic ultrasound for venous leg ulcers. Cochrane Database of Systematic 139. Nelson EA, Bradley MD. Dressings and topical Reviews 2000; 4: CD001180. agents for arterial leg ulcers. Cochrane Database of Systematic Reviews 2003; 1: CD001836. 155. Sari AB-A, Flemming K, Cullum NA et al. Thera- peutic ultrasound for pressure ulcers. Cochrane 140. Springett K. Management of tissue viability. In: Database of Systematic Reviews 2006; 3: Turner WA, Merriman LM, eds. Clinical skills in CD001275. treating the foot, 2nd ed. Edinburgh: Elsevier Churchill Livingstone; 2005: 431–462. 156. Weiss DS, Kirsner R, Eaglstein WH. Electrical stim- ulation and wound healing. Archives of Dermatol- 141. Boulton AJ. Pressure and the diabetic foot: clinical ogy 1990; 126: 222–225. science and offloading techniques. American Journal of Surgery 2004; 187: S17–24. 157. Ravaghi H, Flemming K, Cullum N et al. Electro- magnetic therapy for treating venous leg ulcers. 142. Spencer S. Pressure relieving interventions for pre- Cochrane Database of Systematic Reviews 2006; 2: venting and treating diabetic foot ulcers. Cochrane CD002993. Database of Systematic Reviews 2000; 3: CD002302. 158. Agren MS, Stromberg H-E, Rindby A et al. Selenium, zinc, iron and copper levels in serum 143. Cullum N, McInnes E, Bell-Syer SEM et al. Support of patients with arterial and venous leg ulcers. surfaces for pressure ulcer prevention. Cochrane Acta Dermato-venereologica 1986; 66: 237– Database of Systematic Reviews 2004; 3: 240. CD001735. 159. Balaji P, Mosley JG. Evaluation of vascular and met- 144. Tymec AC, Pieper B, Vollman K. A comparison of abolic deficiency in patients with large leg ulcers. two pressure relieving devices on the prevention of Annals of the Royal College of Surgeons 1995; 77: heel pressure ulcers. Advances in Wound Care 1997; 270–272. 10: 39–44. 160. Wilkinson EAJ, Hawke C. Oral zinc for arterial and 145. Brown AC, Coutts P, Sibbald RG. Compression venous leg ulcers. Cochrane Database of Systematic therapies. In: Krasner DL, Rodeheaver GT, Sibbald Reviews 1998; 4: CD001273. RG, eds. Chronic wound care: a clinical source book for healthcare professionals, 3rd ed. Wayne: HMP 161. Langer G, Schloemer G, Knerr A et al. Nutritional Communications; 2001: 517–524. interventions for preventing and treating pressure ulcers. Cochrane Database of Systematic Reviews 146. Nelson EA, Bell-Syer SEM, Cullum NA. Compres- 2003; 4: CD003216. sion for preventing recurrence of venous ulcers. Cochrane Database of Systematic Reviews 2000; 4: 162. Bourdel-Marchasson I, Barateau M, Rondeau V et CD002303. al. A multi-centre trial of the effects of oral nutri- tional supplementation in critically ill older inpa- 147. Banwell PE. Topical negative pressure therapy in tients. Nutrition 2000; 16: 1–5. wound care. Journal of Wound Care 1999; 8: 79–84. 163. James DR, Holland BM, Hughes MR et al. Oxpentifylline: effects on red cell deformability and 148. Evans D, Land L. Topical negative pressure for oxygen availability from the blood in intermittent treating chronic wounds. Cochrane Database of Sys- claudication. Clinical Hemorheology 1984; 4: tematic Reviews 2001; 1: CD001898. 525–531. 149. Wang C, Schwaitzberg S, Berliner E et al. Hyper- 164. Brenner MA. Nonhealing venous stasis ulcers: pent- baric oxygen for treating wounds: A systematic oxifylline as adjunctive therapy. Journal of the Amer- review of the literature. Archives of Surgery 2003; ican Podiatric Medical Association 1987; 77: 138: 272–279. 586–588.

148 PERIPHERAL VASCULAR DISORDERS AND FOOT ULCERATION 165. Jull AB, Waters J, Arroll B. Pentoxifylline for treat- wound care : a clinical source book for healthcare ing venous leg ulcers. Cochrane Database of System- professionals, 3rd ed. Wayne: HMP Communica- atic Reviews 2002; 1: CD001733. tions; 2001: 343–356. 175. Schultz GS, Sibbald RG, Falanga V et al. Wound 166. Williamson D, Sibbald RG. Skin substitutes. In: bed preparation: a systematic approach to wound Krasner DL, Rodeheaver GT, Sibbald RG, eds. management. Wound Repair and Regeneration Chronic wound care : a clinical source book for 2003; 11: S1–28. healthcare professionals, 3rd ed. Wayne: HMP Com- 176. Gardner SE, Frantz RA, Troia C et al. A tool to munications; 2001: 541–552. assess clinical signs and symptoms of localized infec- tion in chronic wounds: development and reliability. 167. Marston WA. Dermagraft, a bioengineered human Ostomy and Wound Management 2001; 47: dermal equivalent for the treatment of chronic non- 40–47. healing diabetic foot ulcer. Expert Reviews of 177. Diehr S, Hamp A, Jamieson B et al. Do topical Medical Devices 2004; 1: 21–31. antibiotics improve wound healing? Journal of Family Practice 2007; 56: 140–144. 168. Jones JE, Nelson EA. Skin grafting for venous leg 178. White RJ, Cutting K, Kingsley A. Topical anti- ulcers. Cochrane Database of Systematic Reviews microbials in the control of wound bioburden. 2000; 2: CD001737. Ostomy and Wound Management 2006; 52: 26–58. 169. Veves A, Falanga V, Armstrong DG et al. Graftskin, 179. Romanelli M, Magliaro A, Mastronicola D et al. a human skin equivalent, is effective in the manage- Systemic antimicrobial therapies for pressure ulcers. ment of noninfected neuropathic diabetic foot Ostomy and Wound Management 2003; 49: ulcers. Diabetes Care 2001; 24: 290–295. S25–S29. 180. Hopf HW, Ueno C, Aslam A et al. Guidelines 170. Caravaggi C, DeGiglio R, Pritelli C et al. HYAFF for the treatment of arterial insufficiency ulcers. 11-based autologous dermal and epidermal grafts in Wound Repair and Regeneration 2006; 14: the treatment of noninfected diabetic plantar and 693–710. dorsal foot ulcers. Diabetes Care 2003; 26: 181. Robson MC, Cooper DM, Aslam R et al. Guidelines 2853–2859. for the treatment of venous ulcers. Wound Repair and Regeneration 2006; 14: 649–662. 171. Marston WA, Hanft J, Norwood P et al. The efficacy 182. Steed DL, Attinger C, Colaizzi T et al. Guidelines and safety of Dermagraft in the improving the for the treatment of diabetic ulcers. Wound Repair healing of chronic diabetic foot ulcers. Diabetes and Regeneration 2006; 14: 680–692. Care 2003; 26: 1701–1705. 183. Whitney J, Phillips L, Aslam R et al. Guidelines for the treatment of pressure ulcers. Wound Repair and 172. Ehrenreich M, Ruszczak Z. Update on tissue-engi- Regeneration 2006; 14: 663–679. neered biological dressings. Tissue Engineering 2006; 12: 2407–2424. 173. Frank C, Bayoumi I, Westendorp C. Approach to infected skin ulcers. Canadian Family Physician 2005; 51: 1352–1359. 174. Dow G. Infection in chronic wounds. In: Krasner DL, Rodeheaver GT, Sibbald RG, eds. Chronic

Disorders of the toes CHAPTER 8 CHAPTER CONTENTS HALLUX VALGUS Hallux valgus 149 150 Hallux valgus (also referred to as hallux abductoval- Classification and clinical presentation gus) is a common condition affecting the forefoot in Aetiology 150 which the first metatarsophalangeal joint is progres- Assessment and diagnosis 153 sively subluxed as a result of lateral deviation of the Treatment 153 hallux and medial deviation of the first metatarsal.1,2 The condition is frequently accompanied by a painful Hallux limitus and hallux rigidus 157 soft tissue and osseous prominence on the medial Classification and clinical presentation 158 aspect of the first metatarsal head, commonly referred Aetiology 158 to as a ‘bunion’ (Fig. 8.1). As the deformity pro- Assessment and diagnosis 161 gresses, the lateral displacement of the hallux inter- Treatment 162 feres with the normal alignment and function of the lesser toes, resulting in hammer toe or claw toe defor- Lesser toe deformities 165 165 mities, altered weightbearing patterns and the devel- Classification and clinical presentation opment of plantar keratotic lesions. Pressure from Aetiology 166 footwear may also lead to the formation of an adventi- Assessment and diagnosis 167 tious bursa over the joint, which may become inflamed Treatment 167 (Fig. 8.2).3 Less common disorders affecting the The exact prevalence of hallux valgus is difficult toes 168 to determine because of the paucity of large- Tailor’s bunion 168 scale epidemiological studies and varying definitions Hallux varus 169 used in the literature. In people aged over 65 years Gouty arthritis 169 of age, prevalence rates ranging from 5% to 37% have been reported.4–9 Women are significantly more likely Summary 170 to develop hallux valgus than men, with sex ratios References 171 as high as 9 : 1.1,2 The condition has a significant impact on balance10 and gait patterns11 and is an independent risk factor for falls.12 A recent study also demonstrated that people with hallux valgus exhib- ited significantly lower scores on a health-related quality of life questionnaire,13 suggesting that the condition has a much broader impact than local pain and discomfort.

150 DISORDERS OF THE TOES A Figure 8.2 Bursal inflammation resulting from footwear pressure in an older person with hallux valgus deformity. (Courtesy of Mark Gilheany, East Mebourne Podiatry.) Table 8.1 Classification of hallux valgus according to radiographic measurements Classification Hallux abductus Intermetatarsal angle (°) angle (°) B Mild <20 <11 Figure 8.1A, B Severe hallux valgus. (Courtesy of Lesley Moderate 20–40 11–16 Newcombe, La Trobe University.) Severe >40 >16 CLASSIFICATION AND gradings using this scale were significantly associated CLINICAL PRESENTATION with hallux abductus and intermetatarsal angles obtained from foot radiographs. Although this scale Hallux valgus is generally deemed to be present when does not provide any information regarding the the angle formed by the bisection of the first meta- degree of joint degeneration or sesamoid displace- tarsal and the proximal phalanx (the hallux abductus ment, it is a very useful tool for documenting the angle) is greater than 15° and the angle formed by overall severity of angular displacement of the hallux the bisection of the first metatarsal and second meta- in clinical settings where radiographs are not readily tarsal (the intermetatarsal angle) is greater than 9°.1,14 available or are considered unnecessary. Several classification systems have been proposed based on the degree of angular deformity and the AETIOLOGY severity of symptoms, primarily to assist in the selec- tion of surgical procedures. Mann15 has proposed a The aetiology of hallux valgus is not well understood. simple grading system based on the hallux abductus There is some evidence that the condition is an auto- and intermetatarsal angles, which has been widely somal dominant trait with partial penetrance, as adopted for presurgical planning (Table 8.1). The between 58% and 90% of people with hallux valgus simplest clinical grading system is the Manchester report a familial tendency.1,18,19 Johnston20 docu- scale,16 which consists of four standardised photos mented 101 family members across seven generations covering the spectrum of the deformity (Fig. 3.6). A and reported that all but two affected parents passed recent study by Menz & Munteanu17 showed that

Hallux valgus 151 the condition on to their children. More recently, among people who wear shoes and, at the very least, Pique-Vidal et al19 constructed pedigree charts from the wearing of ill-fitting shoes is likely to aggravate 350 patients across three generations and found that pre-existing hallux valgus, particularly in those with a family history was positive in 90% of cases, with verti- very broad forefoot.3 cal transmission affecting some families across all three generations. However, because congenital hallux Metatarsus primus varus valgus is extremely rare, it appears that some intrinsic structural or functional tendency is inherited that may Metatarsus primus varus (also referred to as metatar- take several decades to develop into hallux valgus. sus primus adductus) refers to excessive angulation of the first metatarsal relative to the second metatarsal, Because of this prolonged timeframe, our under- and is generally considered to be present when the standing of potential risk factors is limited to case- intermetatarsal angle is greater than 14°.37 Metatarsus control studies, which provide evidence of association primus varus is an inherent anatomical variant caused but not causation. Indeed, many of the proposed risk by the oblique orientation of the first metatarsocunei- factors for hallux valgus could plausibly be argued to form joint, and is thought to predispose to hallux be consequences of the condition rather than causes. valgus as a result of the bowstringing of the flexor The most commonly proposed aetiological factors for hallucis longus tendon pulling the proximal phalanx hallux valgus are footwear, metatarsus primus varus, into an abducted position.38 However, while there is long first metatarsal, metatarsal head shape, muscle a strong correlation between metatarsus primus varus dysfunction and foot pronation. Each of these factors and hallux valgus,1 it has also been observed that, as is briefly outlined below; however, for a more com- the lateral deviation of the hallux increases with prehensive discussion, the reader is referred to Kilmar- increasing severity of the condition, the intermetatar- tin & Wallace.21 sal angle also increases.17 As such, it is also possible that metatarsus primus varus is a result, rather than a Footwear cause, of hallux valgus. The suggestion that footwear may be a contributing Long first metatarsal factor to the development of hallux valgus is driven by three major observations reported in the literature: An overly long first metatarsal as a potential cause of the very low prevalence of the condition in people hallux valgus was first proposed by Hardy & Clapham,1 who do not wear shoes,22–24 the increase in prevalence who reported that the first metatarsal was on average observed when footwear is introduced into previously 4 mm longer than the second metatarsal in 91 patients non-shoewearing populations25–29 and the significantly with hallux valgus, compared to an average of 2 mm higher prevalence of the condition in women, many longer in 84 people without hallux valgus. Similar of whom wear shoes with an elevated heel and narrow results were reported in two subsequent studies.39,40 toebox.30 It is physiologically plausible that wearing The proposed mechanism for the relationship between narrow-fitting shoes may result in the foot adapting long first metatarsal and hallux valgus is simply that to the confined space within the shoe via lateral devia- the longer first ray segment is more likely to undergo tion of the hallux and that, over time, soft tissue compression from footwear and, because of the angu- contracture and bony remodelling may cause the foot lation of the first metatarsal relative to the second, the to assume this new position. The contribution of heel hallux is predisposed to deviate laterally towards the elevation is less clear, as many shoes with an elevated lesser toes.40 As it is unlikely that hallux valgus will heel also have a narrow toe box, making a delineation lead to a lengthening of the first metatarsal, causality between the contribution of each feature difficult. is perhaps more convincing for long first metatarsal However, there is evidence that heel elevation alters than for other hypothesised intrinsic factors. the kinematics of the first metatarsophalangeal joint31,32 and leads to a medial shift in weightbearing Metatarsal head shape pressures during gait,33–36 factors that may contribute to the gradual lateral displacement of the hallux. Two broad categories of the shape of the first meta- While the contribution of footwear to the develop- tarsal head were identified by Mann & Coughlin2 in ment of hallux valgus is unlikely to be adequately 1981 – round and square. Theoretically, hallux valgus resolved, it is clear that the condition is more common

152 DISORDERS OF THE TOES would be more likely to occur in feet with a round controls and reported that the hallux valgus group first metatarsal head, as this articular configuration exhibited slightly greater dorsiflexory motion (12.9° would facilitate the transverse plane rotation of the versus 10.3°). proximal phalanx. In contrast, a square first metatarsal head would act to resist transverse plane forces placed Foot pronation on the hallux from footwear.14 There is limited evi- dence to support metatarsal head shape as a contribut- The proposed association between pronated/flat feet ing factor to hallux valgus. Indeed, a study of 50 and hallux valgus dates back as far as 189321 but, children with hallux valgus found that 40 exhibited despite several authors noting that the condition square metatarsal heads.41 Furthermore, establishing seems to be more common in people with flat feet,50 such a relationship in older people with hallux valgus there have been few case-control studies conducted would be difficult, as arthritic degeneration in long- to adequately address this relationship. The theory standing hallux valgus results in marked changes to espoused by Root et al,51 widely adopted by the podi- the architecture of the metatarsal head. atry profession, suggests that subtalar joint pronation renders the forefoot hypermobile, thereby allowing Muscle dysfunction ground reaction forces to dorsiflex and invert the first metatarsal, which then results in erosion of the inter- Several authors have suggested that an imbalance sesamoidal ridge by the tibial sesamoid and subse- between the abductor and adductor hallucis muscles, quent lateral displacement of the proximal phalanx. with the latter overpowering the former, may have the Evidence to support this assertion is scarce. Indeed, effect of pulling the proximal phalanx laterally, thereby two studies comparing foot posture measurements initiating the development of hallux valgus.2,42 Elec- between children with and without hallux valgus have tromyographic studies have confirmed that there is failed to find any significant differences between the indeed a reduction in abductor hallucis muscle activity two groups.52,53 In contrast, Kernozek et al54 recently in people with hallux valgus;43,44 however, whether reported that 40 patients with hallux valgus had a this occurs before or after the condition develops is significantly more everted calcaneal stance position unknown. Anomalous tendon insertions have also (indicative of greater foot pronation) compared to 51 been proposed as a potential cause of hallux valgus; controls. Because of significant variations in defini- however, extensive cadaver studies by Brenner failed tions of the flat or pronated foot, it is difficult to to find any differences in the insertion patterns of directly compare these findings. Furthermore, the either tibialis anterior45 or abductor hallucis46 in feet relationship between static foot structure and dynamic with or without the condition. function is, at best, only moderate,55 so until compari- sons are made using kinematic models the relation- First ray hypermobility ship between foot function and hallux valgus will remain elusive. Three case-control studies have provided evidence of the proposed relationship between hypermobility of Other potential causes of hallux valgus the first ray and hallux valgus. Ito et al47 compared changes in the lateral talo-first metatarsal angle from In addition to the proposed intrinsic risk factors non-weightbearing to weightbearing in 32 people described above, hallux valgus has been observed to with hallux valgus and 23 controls, and found that develop secondary to several other systemic condi- those with hallux valgus underwent a greater reduc- tions, including a range of inflammatory joint diseases tion in this angle when bearing weight (indicative of (e.g. rheumatoid arthritis, gout and psoriatic arthro- greater dorsiflexion of the first ray). Consistent with pathy), conditions associated with ligamentous laxity this finding, Glasoe et al48 reported that 14 people (e.g. Ehlers–Danlos syndrome, Marfan’s syndrome with hallux valgus exhibited greater dorsal mobility of and Down’s syndrome), and neuromuscular disorders the first ray compared to age- and sex-matched con- (e.g. cerebral palsy, poliomyelitis and Charcot–Marie– trols when a controlled dorsiflexory force of 55 Tooth disease). Iatrogenic hallux valgus may also Newtons was applied to the first metatarsal head. develop secondary to surgical removal of the tibial Finally, Lee & Young49 measured first ray dorsiflexion sesamoid.15 and metatarsal length 60 hallux valgus cases and 40

Hallux valgus 153 ASSESSMENT AND DIAGNOSIS Figure 8.3 Hallux valgus angles measured from dorso- plantar radiograph. A. Intermetatarsal angle. B. Hallux Assessment and diagnosis of hallux valgus is relatively abductus angle. C. Hallux interphalangeus abductus straightforward. Patients will typically present with an angle. enlarged and painful first metatarsophalangeal joint, with symptoms exacerbated by weightbearing activity and the wearing of ill-fitting or high-heeled footwear. Physical examination will reveal lateral deviation of the hallux and, depending on the severity of the deformity, overcrowding of the lesser toes may have resulted in the development of hammer- or claw-toe deformities. In severe cases, the second toe may be subluxed at the metatarsophalangeal joint and over- or under-ride the deviated hallux. The medial promi- nence of the first metatarsophalangeal joint (the ‘bunion’) may appear inflamed, and in some cases a fluid-filled bursa may have formed over the enlarged dorsomedial aspect of the joint. The hallux nail may be dystrophic or involuted because of pressure from footwear, and the tendon of extensor hallucis longus may be prominent and laterally displaced because of the gradual weakening of the extensor hood. Changes in weightbearing patterns often give rise to the devel- opment of calluses or corns beneath the metatarsal heads, most commonly located under the second metatarsal head because of the hypermobility of the first ray. Further examinations are generally not required to diagnose hallux valgus; however, weightbearing radio- graphs, particularly dorsoplantar views, enable accu- rate grading of the deformity and are essential for surgical planning. Several well-established measure- ments can be derived from a dorsoplantar radiograph: the hallux abductus angle, intermetatarsal angle and hallux interphalangeus abductus angle (Fig. 8.3). This view also provides useful insights into the degree of arthritic degeneration in the joint. Observational gait analysis may reveal reductions in walking speed and step length,11 and plantar pressure analysis will gener- ally reveal a reduction in loading under the hallux and first metatarsal head but a corresponding increase in loading under the lateral metatarsal heads (Fig. 8.4).54,56 TREATMENT Figure 8.4 Typical plantar pressure output for an older person with hallux valgus. Conservative Conservative management of hallux valgus includes measures to obtain pain relief, addressing the associ- ated nail and skin conditions, and the provision of interventions to realign (or at least slow the progres-

154 DISORDERS OF THE TOES sion of) the deformity. All skin lesions and nail disor- hallux valgus. It is particularly important that such ders should be managed as described in Chapters 3 studies include older people, as the degree of arthritic and 5, with particular emphasis placed on ensuring degeneration associated with hallux valgus is likely to that lesions are sufficiently palliated and that the con- influence the likelihood of a successful outcome. tribution of ill-fitting footwear is appropriately addressed. Extra-depth and wider-fitting footwear Surgical may need to be prescribed and fitted, and soft, moulded orthoses inserted to offload painful plantar Surgical intervention for hallux valgus is frequently regions. The application of foam or silicon gel pads indicated, as conservative management is generally to offload the medial prominence may also provide only effective in alleviating symptoms and has little or some degree of symptomatic improvement.57 no impact on the progression of the deformity or its secondary effects on mobility and quality of life. Several conservative techniques have been described However, because hallux valgus is quite variable in its to reduce the degree of hallux valgus and/or prevent presentation, there is no ‘gold standard’ surgical pro- further deformity, including toe splints,58–60 mobilisa- cedure that can be applied to all patients. Rather, the tion and manipulation,61 and foot orthoses.62–64 condition needs to be viewed as a syndrome consist- However, a recent Cochrane systematic review found ing of multiple pathologies, and careful presurgical only two randomised controlled trials of conservative planning is therefore recommended to achieve optimal treatments involving adults. Juriansz58 compared a outcomes.65 hallux valgus night splint to no treatment in 28 people ranging in age from 10 to 77 years and found no When considering surgical intervention for hallux difference in clinically determined degree of defor- valgus, the potential adverse effects need to be care- mity. Torkki et al64 compared the effectiveness of fully considered. Although it is difficult to predict the surgery, customised orthoses and no treatment in 211 outcome in hallux valgus surgery, Rowley66 has sug- patients and reported that orthoses significantly gested that, in general, 70–80% of patients do well, reduced pain after 6 months compared to no treat- 10–15% have a satisfactory outcome and 5–10% have ment, but this difference was not evident at 12 an unsatisfactory outcome or are actually worse off months. As no radiographs or clinical measurements following the procedure. However, the recent were taken, it is unclear whether the degree of defor- Cochrane review67 of 18 randomised trials reported mity was affected by treatment. In a randomised con- that up to one-third of patients were dissatisfied with trolled trial that was not eligible for inclusion in the their surgical result. Common complications associ- Cochrane review, Budiman-Mak et al63 demonstrated ated with hallux valgus surgery include ongoing pain, that people with rheumatoid arthritis issued with foot transfer lesions (the development of lesions at previ- orthoses were less likely to exhibit progression of the ously lesion-free sites because of changes in foot func- hallux abductus angle to the no-treatment control tion), joint stiffness, stress fractures, ‘floating hallux’ group after a 3-year follow-up period. (loss of function of the hallux due to plantarflexion weakness) and irritation from internal fixation devices Since the publication of the Cochrane review, two (K-wires and screws).68,69 Two recent studies have also additional conservative treatment studies have been indicated that, while hallux valgus surgery reduces published. Tang et al59 conducted an uncontrolled pain and improves quality of life, the appearance of study of an insole with a toe separator to realign the the foot and the range of shoes that can be worn fol- hallux in 17 patients aged 14–75 years, and reported lowing the procedure are significant predictors of sat- an average 6.5° reduction in the hallux abductus angle isfaction with the surgical result.70,71 and improvements in pain and walking ability at 3 months. More recently, Brantingham et al61 con- Over 150 different procedures have been described ducted a randomised controlled trial comparing chi- for hallux valgus, involving bony or soft tissue correc- ropractic manipulation and mobilisation (including tion, or a combination of both.67 The simplest proce- longitudinal distraction and adduction of the hallux) dure is Silver’s bunionectomy,72 which involves the to a sham treatment and reported significant improve- removal of the medial eminence of bone without cor- ments in pain threshold and Foot Function Index recting the underlying angular deformity. More scores in the treatment group over a 3-week period. complex procedures may involve fusion of the first metatarsophalangeal joint, displacement of the first Clearly, further research is required to thoroughly metatarsal head, shortening of the first metatarsal, evaluate the efficacy of conservative treatments for

AB Hallux valgus 155 AB Figure 8.5 Keller’s arthroplasty. A. Shaded areas to be Figure 8.6 Akin procedure. A. Wedge-shaped piece of removed. B. Postoperative result. Note significant bone to be removed. B. Fixation with threaded Kirschner shortening of first ray. wire. plantarflexing or dorsiflexing the first ray, reducing AB the intermetatarsal angle by removing a wedge of bone from the base of the first metatarsal, and various Figure 8.7 Scarf osteotomy. A. Lateral view of tendon lengthening and shortening procedures.69 metatarsal showing Z-shaped step cut osteotomy. The following section briefly describes some of the B. Dorsal view of plantar cortical fragment being rotated more commonly performed techniques. For a more laterally. detailed coverage, the reader is referred to a recent comprehensive review by Kilmartin69 and to specialist fragment are then translated laterally and fixed with foot surgery texts.73 two compression screws (Fig. 8.7). The scarf osteot- omy is particularly useful for correcting large inter- The technique now known as the Keller procedure metatarsal angles and is comparatively stable; however, was originally described in the German literature but it is a technically demanding operation that requires was translated into English by Keller in 1904.74 This considerable surgical expertise.65 common and technically straightforward procedure involves removing the base of the proximal phalanx The Lapidus procedure was described in 1934.76 and medial eminence of the first metatarsal (Fig. 8.5). This technique involves removal of the medial promi- As no further correction of the angular deformity is nence, followed by fusion of the metatarsocuneiform undertaken, recurrence is common and it has there- joint in conjunction with the insertion of bone chips fore been suggested that this procedure is suited to taken from the medial eminence in the space between older people who are not physically active.69 the first and second metatarsals. This procedure is considered to be particularly useful for surgical cor- The Akin procedure was described in 192575 and rection of hallux valgus with large intermetatarsal involves resection of the medial eminence followed by angles and/or arthritic degeneration of the metatar- the removal of a wedge-shaped piece of bone from the base of the proximal phalanx (Fig. 8.6). In con- temporary practice, this procedure is rarely under- taken as a stand-alone surgery but may be combined with other osteotomies. In addition to correcting the transverse plane alignment of the hallux, the osteot- omy can be angled to provide correction in the frontal plane if required.69 The scarf osteotomy was described in 192669 and is based on (and named after) a joint commonly used in carpentry. The technique involves making a longi- tudinal, Z-shaped step-cut osteotomy through the metatarsal. The metatarsal head and plantar cortical

156 DISORDERS OF THE TOES AB AB Figure 8.8 Mitchell osteotomy. A. Shaded section of Figure 8.9 Wilson osteotomy. A. Shaded section of bone bone to be removed. B. Metatarsal head displaced to be removed and oblique cut made through metatarsal laterally and proximally. neck. B. Distal segment slid laterally and proximally. socuneiform joint; however, common complications AB associated with the technique include non-union, overcorrection leading to hallux varus, and develop- Figure 8.10 Chevron osteotomy. A. Lateral view of ment of secondary osteoarthritis in adjacent joints.69 V-shaped osteotomy through metatarsal neck. B. Metatarsal head slid laterally. The Mitchell osteotomy, described by Hawkins in 1945,77 involves removing a rectangular section of avascular necrosis is relatively common as a result of bone from the metatarsal neck and displacing the severing the arterial supply to the metatarsal head.69 metatarsal head laterally and proximally (Fig. 8.8). Furthermore, it has been suggested that the tech- The procedure invariably results in some shortening nique is inappropriate in cases where the intermeta- of the metatarsal, which may be responsible for the tarsal angle is greater than 15°. relatively common occurrence of transfer lesions in some patients. A long-term follow-up study of 95 Basal osteotomies involve making an osteotomy cut patients (mean follow-up of 21 years) by Fokter through the base of the first metatarsal and then lever- et al78 indicated a very high (52%) recurrence rate ing the metatarsal laterally to ‘close’ the intermetatar- associated with the procedure. sal angle.65 The two most common types are the closing wedge osteotomy, in which a wedge of bone is The Wilson osteotomy was developed in the 1950s79 removed on the lateral aspect of the base of the first and is similar to the Mitchell osteotomy; however, metatarsal, and the crescentic osteotomy, in which a rather than removing a rectangular section of bone, proximally directed concave osteotomy is made 1 cm an oblique osteotomy is made through the metatarsal distal to the metatarsocuneiform joint and the meta- neck, enabling the metatarsal head to be slid laterally tarsal is rotated laterally (Fig. 8.11). Basal osteotomies and proximally (Fig. 8.9). As with the Mitchell pro- cedure, transfer lesions and metatarsalgia are rela- tively common (up to 33%) because of metatarsal shortening.80 The Chevron procedure was first described in 197981 and has become one of the most commonly per- formed surgical techniques for adult hallux valgus. The procedure involves separating the metatarsal head from the metatarsal neck using a V-shaped oste- otomy, sliding the metatarsal head laterally and insert- ing K-wires or screws to hold the metatarsal head in its new position (Fig. 8.10). The benefits of the tech- nique are its technical simplicity and stability; however,

Hallux limitus and hallux rigidus 157 A been adequately examined or directly compared to other techniques. The most recent Cochrane review of treatments for hallux valgus67 identified only 18 studies in which patients had been randomly allocated to different interventions, and only one that used a no-treatment control group for comparison.64 Although one study demonstrated that patients undergoing a Chevron osteotomy had better out- comes than patients receiving foot orthoses,64 no sur- gical techniques were found to be superior to any other and the number of participants expressing dis- satisfaction at follow-up was consistently high (25– 33%). Furthermore, three trials comparing procedures as they were originally described to the surgeon’s B modification of the technique reported no significant advantages for the modification. Clearly, there is con- siderable scope for future research into the relative merits of different surgical techniques for hallux valgus. HALLUX LIMITUS AND HALLUX RIGIDUS Figure 8.11 Basal osteotomies. A. Crescentic. B. Closing Hallux limitus is a condition in which there is a base wedge. restriction in the range of motion of the first metatar- sophalangeal joint. If this progresses to complete are indicated for the correction of large intermetatar- fusion of the joint, the term hallux rigidus is used, sal angles; however, because the technique results although the two terms are frequently used inter- in metatarsal shortening, transfer metatarsalgia is a changeably.82,83 Rzonca et al84 argued that the term common complication.69 hallux equinus should be used to encompass the entire spectrum of the condition; however, this terminology Arthrodesis (fusion) of the first metatarsophalan- has not been widely adopted. Other less commonly geal joint following resection of cartilage from the used terms related to the condition are dorsal bunion85 metatarsal head and proximal phalanx is a destructive and hallux flexus,86 the former used when there is procedure that is generally reserved for hallux valgus evidence of an osseous prominence on the dorsal with severe joint degeneration. Once fused, the hallux aspect of the joint, and the latter when the resting position cannot be altered, and for this reason the position of the hallux is in flexion. angle at which the fusion is performed is extremely important. Excessive dorsiflexion may lead to the The condition was first described by Coterill in development of calluses under the first metatarsal 188787 and was primarily considered to be an afflic- head, whereas inadequate dorsiflexion may result in tion of adolescents that developed in response to arthritic degeneration of the interphalangeal joint of trauma (e.g. stubbing the toe) or ill-fitting footwear. the hallux.69 For these reasons, arthrodesis is generally Hallux limitus/rigidus is also considered to be a ‘last resort’ and the decision to fuse the joint must common in older people; however, the precise epide- be very carefully considered. miology is very difficult to determine as the condition is rarely included in large-scale surveys. Furthermore, Despite the large number of surgical procedures there is some overlap between hallux limitus/rigidus that have been described for hallux valgus, few have and osteoarthritis of the first metatarsophalangeal joint, which in one large-scale study was found to affect 44% of people over the age of 80 years.88 There is a general consensus that women are affected twice as commonly as men.89

158 DISORDERS OF THE TOES In addition to ‘structural’ hallux limitus/rigidus, an additional ‘functional’ form of the condition has been proposed. Functional hallux limitus describes a condition in which there is normal range of motion at the first metatarsophalangeal joint when measured non-weightbearing; however, there is a reduced range of dorsiflexion evident during the propulsive phase of gait.90 The initial cause of this limitation is unclear; however, several authors have suggested that func- tional hallux limitus is a precursor to structural hallux limitus/rigidus.83,91 CLASSIFICATION AND Figure 8.12 Typical presentation of hallux limitus/ CLINICAL PRESENTATION rigidus. Note dorsal exostosis of the first metatarsophalangeal joint, hyperextension the Several classification systems for hallux limitus/rigidus interphalangeal joint and hypertrophy of hallux nail. have been proposed, based on radiographic criteria (Courtesy of Lesley Newcombe, La Trobe University.) alone92–95 or a combination of radiographic and clini- cal features.82–84,96 However, few of these scales have Figure 8.13 Typical plantar pressure output for an older been adequately validated and no direct comparisons person with hallux limitus/rigidus. between the scales have been undertaken. A summary of three of the most commonly reported scales AETIOLOGY (Regnauld,92 Hattrap & Johnson93 and Coughlin & Shurnas97) is provided in Table 8.2. Perhaps the most The aetiology of hallux limitus/rigidus is considered useful grading system is that of Coughlin & Shurnas,98 to be multifactorial; however, few well designed which incorporates clinical and radiographic features studies have been undertaken. Most investigations and provides first metatarsophalangeal joint dorsiflex- have been case series designs, which simply report the ion ranges of motion commonly observed with each prevalence of various features in patients with hallux grade. This scale has also been shown to have prog- limitus/rigidus with no comparison to a control nostic value in determining the response to surgical group. These studies have suggested that hallux intervention. limitus/rigidus is associated with female sex,97 family history of the condition,97 long first metatarsal,101,102 Patients with hallux limitus/rigidus typically increased hallux interphalangeal abductus angle97 and present with complaints of pain and stiffness in their foot pronation.87,101–103 big toe joint that increases with activity and is allevi- ated by rest. Paraesthesia may be present because of compression of the dorsal digital nerve of the hallux. On examination, the first metatarsophalangeal joint may be swollen and erythematous and in long-stand- ing cases there will be a dorsal exostosis overlying the first metatarsal head (Fig. 8.12). Secondary features include bursal formation, hyperextension of the inter- phalangeal joint with associated hallux nail dystrophy, and keratotic lesions, typically located under the medial aspect of the interphalangeal joint and lesser metatarsophalangeal joints. Gait analysis will reveal an apropulsive walking pattern with a shortened step length, possibly accompanied by excessive knee and hip flexion or hip circumduction to assist the transfer of the swing limb. Plantar pressures will generally be elevated beneath the hallux and lateral metatarsal heads (Fig. 8.13).99,100

Table 8.2 Classification systems for hallux limitus/rigidus Regnauld Hattrap & Johnson Coughlin & Shurnas Findings Radiographic Radiographic Radiographic Clinical 1st MPJ DF ROM Grade 0 – – Normal No pain 40–60° and/or Slight stiffness 10–20% loss Grade 1 Condensation of bone Mild to moderate Dorsal osteophyte Reduced ROM compared to Grade 2 around the joint osteophytes Minimal joint space narrowing normal side Grade 3 Minimal periarticular sclerosis Mild/occasional pain Grade 4 Slight narrowing of Normal joint space Minimal flattening of metatarsal head and stiffness 30–40° and/or joint space 20–50% loss Moderate Dorsal, lateral and possibly medial Pain at extremes of DF compared to Sesamoids regular but osteophytes osteophytes and/or PF normal side enlarged Joint space Flattened appearance of metatarsal head Moderate to severe 10–30° and/or Moderate osteophytes narrowing No more than one-quarter of dorsal joint pain and stiffness 50–75% loss Joint space narrowing that may be compared to Subchondral sclerosis or Subchondral space involved on lateral radiograph constant normal side sclerosis Mild-moderate joint space narrowing and cysts Pain occurs just before Hypertrophy and Marked osteophytes sclerosis maximum DF and Loss of joint space Sesamoids not involved maximum PF irregularity of Subchondral cysts sesamoids As for Grade 2, but with substantial Nearly constant pain ≤10° and/or 75– Hallux limitus and hallux rigidus 159 present or absent narrowing, possible periarticular cystic and substantial 100% loss Severe osteophytes changes, more than one-quarter of stiffness at extremes compared with Complete disappearance – dorsal joint space involved on lateral of range of motion, normal side radiograph but not at mid-range of joint space Notable loss of Degenerative hallux- Sesamoids enlarged and/or cystic or PF irregular metatarsosesamoid As for Grade 3 plus As for Grade 3 joint As for Grade 3 definite pain at mid- range of passive – motion 1st MPJ DF ROM, first metatarsophalangeal joint dorsiflexion range of motion, measured passively; PF, plantarflexion.

160 DISORDERS OF THE TOES Stronger evidence can be derived from case-control A Normal function studies, as direct comparisons are made to a control group without the condition. Four such studies have B Limited motion been undertaken. Horton et al104 compared radio- graphic measurements in 81 patients with hallux C Rigid deformity rigidus and 50 controls and found that, while mea- Figure 8.14 Pathomechanics of hallux limitus. A. Normal sures of metatarsus primus elevatus (relative elevation function of the first MPJ. B. compression of joint of the first metatarsal compared to the second meta- associated with hallux limitus. C. Formation of tarsal) were similar between controls and cases with osteophyte on dorsal aspect of the joint. mild to moderate deformity, severe cases of hallux rigidus demonstrated slightly higher mean values. one of progressive arthritic degeneration of the first Similar results were reported by Roukis,105 who com- metatarsophalangeal joint, initiated by synovial hyper- pared 100 cases of hallux rigidus to historical controls trophy and subsequent cartilage destruction. Loss of and found that metatarsus primus elevatus was more cartilage results in exposure of subchondral bone, common in the case group. Zgonis et al106 compared which then undergoes sclerotic changes and, in severe radiographic features in 51 hallux rigidus cases to 51 cases, formation of subchondral cysts.82 controls and reported that the first metatarsal was slightly shorter in the hallux rigidus group (65 mm Finally, hallux limitus/rigidus has also been re- compared to 68 mm). However, first metatarsal pro- ported in people with arthritic disorders such as rheu- trusion distance, which is a more functional indicator matoid arthritis, gout and psoriatic arthropathy.82 The of the length of the first metatarsal as it takes into underlying mechanism for the development of limited account transverse plane angulation, did not differ joint motion in these conditions is likely to be localised between the groups. Bryant et al107 compared radio- joint inflammation and subsequent cartilage degen- graphic measurements in 30 people with hallux limitus eration. However, Clayton & Ries113 have also sug- and 30 controls and reported an increased hallux gested that, in the rheumatoid foot, spasm of intrinsic interphalangeus abductus angle in the hallux limitus musculature of the toes may occur in an attempt to group. Finally, a large retrospective cohort study of unload painful lesser metatarsal heads, resulting in 1592 people aged over 40 years found that those with osteoarthritis of the first metatarsophalangeal joint were more likely to have pronated feet, defined as a frontal plane rearfoot angle of greater than 5°.108 These findings indicate that intrinsic structural factors may play a role in the development of hallux limitus/rigidus. The underlying mechanical cause of the degeneration of the joint, however, is subject to considerable debate. It has been hypothesised that subtalar joint pronation leads to first ray hypermobil- ity and that the subsequent dorsiflexion of the first metatarsal limits the dorsal excursion of the proximal phalanx, leading to a ‘jamming’ of the joint (Fig. 8.14).51 This process would theoretically be exacer- bated in the presence of an overly long or elevated first metatarsal. However, while reduced static dorsi- flexion of the first metatarsophalangeal joint has been shown to be associated with pronated foot posture109,110 and decreases as the rearfoot is progressively everted,111 the relationship between eversion of the rearfoot complex and maximum first metatarsophalangeal joint dorsiflexion during gait is only moderate.112 Irrespective of the underlying intrinsic risk factors, the essential pathology of hallux limitus/rigidus is

Hallux limitus and hallux rigidus 161 soft tissue contracture of the first metatarsophalangeal indicating that a cut-off value of approximately 50° is joint. probably a useful rule of thumb when assessing older people. If the condition is unilateral, it may be useful ASSESSMENT AND DIAGNOSIS to compare the range of motion between both feet and document the relative reduction in motion on the Diagnosis of hallux limitus/rigidus is based on clinical affected side.97 signs and symptoms, joint range of motion measure- ment and radiographic appearance. As stated above, Weightbearing dorsoplantar and lateral radiographs the classical presentation of hallux limitus/rigidus is are extremely useful to determine the severity of pain and stiffness in the first metatarsophalangeal joint hallux limitus/rigidus (Fig. 8.16). The most obvious that increases with activity and is alleviated by rest. features of the condition are joint space narrowing Physical examination will frequently reveal a dorsal and juxta-articular sclerosis (best viewed from the exostosis overlying the joint with associated inflam- dorsoplantar radiograph), and the formation of an mation and, in severe cases, bursal formation. osteophyte on the dorsal aspect of the first metatarsal head (best viewed from the lateral radiograph). As the Non-weightbearing examination of the first meta- condition progresses, the metatarsal head takes on a tarsophalangeal joint (Fig. 8.15) will reveal a limited flattened appearance, the sesamoids may become range of dorsiflexion with normal or slightly restricted enlarged, and periarticular cysts may develop. Oblique plantarflexion. The normal non-weightbearing range of motion of the first metatarsophalangeal joint has been reported to be between 50° and 82°;114–118 however, several measurement techniques have been described, which may not be directly comparable.118 Furthermore, these normal ranges may not be appli- cable to older people, because of normal age-related reductions in joint range of motion. Recently, Scott et al119 showed that older people without foot prob- lems had significantly less range of motion at the first metatarsophalangeal joint compared to younger con- trols (56° versus 82°, measured non-weightbearing), A Figure 8.15 Non-weightbearing range of motion B assessment of the first metatarsophalangeal joint. The older person is seated with the knee extended and ankle Figure 8.16 Radiographic appearance of hallux limitus. placed at 90°, and the hallux is maximally extended. The A. Dorso-plantar view. B. Lateral view. value recorded is the maximum angle at which the hallux cannot be passively moved into further extension.

162 DISORDERS OF THE TOES radiographs are not essential to assess the severity of to play in the management of hallux limitus/rigidus hallux limitus/rigidus; however, they may assist in but appears to be more effective in less severe cases. determining the full extent of the dorsal osteophyte. More recently, a randomised controlled trial by Pons Similarly, computed tomography scans are generally et al124 indicated that intra-articular injection of not required but may assist in determining the degree sodium hyaluronate, a highly viscous glycosaminogly- of degeneration on the plantar surface of the joint, can thought to influence cartilage metabolism, was which is otherwise difficult to visualise with more effective than corticosteroid injection in early radiographs. hallux rigidus. However, after one year, nearly half the participants required surgical intervention, sug- TREATMENT gesting that the benefits of this approach may be short-term. Conservative Mobilisation of the sesamoid apparatus and Conservative management of hallux limitus/rigidus strengthening of hallux plantarflexors has also been involves measures to obtain pain relief (including anti- shown to confer an additional benefit in the conserva- inflammatory medications and intra-articular cortico- tive management of hallux limitus. Shamus et al125 steroid injection), addressing the associated nail and conducted a small trial in which one group of patients skin conditions, physical therapy to restore range of was provided with whirlpool, therapeutic ultrasound, motion, orthotic therapy and footwear modifica- first metatarsophalangeal joint mobilisation, calf tions.120 Although very few rigorous trials have been stretching, toe strengthening exercises, cold packs undertaken to assess the efficacy of these treatments and electrical stimulation, and the second group was for hallux limitus/rigidus, case series studies suggest provided with each of these interventions in addition that many patients benefit from conservative manage- to distal gliding mobilisations of the sesamoids, hallux ment. In a recent 14-year follow-up study of patients plantarflexor strengthening exercises and gait train- who chose not to have surgery, few reported that their ing. After 12 therapy sessions, the group who received condition had worsened and 75% would still choose the sesamoid mobilisations exhibited greater improve- not to have surgery if they had to make the decision ments in first metatarsophalangeal joint range of again. A large proportion of these patients had motion, toe flexor strength and pain levels. changed their footwear to shoes with a more ample toebox, suggesting that selection of appropriate foot- Footwear modification and orthotic management wear may be a sufficient treatment in many people.121 of hallux limitus/rigidus are greatly influenced by the Similar findings were reported by Grady et al,122 who severity of the condition. In advanced cases with large reviewed 772 cases of hallux limitus over a 7-year osteophytes, pain generally occurs during the propul- period and reported that 55% were successfully sive phase of gait when the proximal phalanx jams managed with conservative care alone. Of these, 84% against the metatarsal head. In such cases, the goal of were managed with foot orthoses, 10% with intra- treatment is to restrict motion. This can be achieved articular corticosteroid injections and 6% with a by the prescription of shoes with a rigid shank; change in footwear. however, the resultant need for sagittal plane compensation at the knee and hip may create symp- Intra-articular injection and manipulation may be toms further up the kinetic chain. Alternatively, rocker beneficial in mild to moderate cases of hallux limitus/ sole footwear will enable propulsion to occur prox- rigidus. Solan et al123 described a case series of 31 imal to the metatarsophalangeal joints, provided patients with hallux rigidus who were given an injec- the apex of the rocker is appropriately located. Pre- tion of 40 mg of Depo-Medrone and 3 ml of 0.5% scription of rocker-soled footwear needs to be care- bupivacaine followed by manipulation of the joint fully considered in older people, as some patients may under general anaesthesia. After a mean follow-up of take considerable time to adjust to the footwear 41 months, one-third of patients with mild (Karasick because of balance difficulties. For those with severe & Wapner95 grade 1) hallux rigidus required surgery, hallux limitus/rigidus who are not suitable for rocker- two-thirds of patients with moderate (grade 2) hallux sole shoes, the placement of an insole with a raised rigidus required surgery, and all patients with advanced bar under the first ray may achieve the same (grade 3) hallux rigidus required surgery. The authors result.126 concluded that manipulation and injection has a role For less severe forms of hallux limitus (including functional hallux limitus), orthoses may assist in facili-

Hallux limitus and hallux rigidus 163 tating sagittal plane motion of the first metatarsopha- complication being recurrence of the dorsal osteo- langeal joint by increasing the plantarflexion of the phyte.93,132–136 Feltham et al137 have stated that the first ray. This may be achieved by removing orthotic technique is particularly effective in people aged over material beneath the first ray segment (‘first ray cut- 60 years who have extra-articular symptoms. out’), elevating the lateral metatarsal heads (via valgus forefoot wedges or metatarsal domes) or placing a Several joint preservation osteotomy procedures firm piece of material beneath the hallux.127 Despite have been proposed for the surgical management of the proposed relationship between foot pronation and hallux limitus/rigidus (Fig. 8.17). The Bonney–Kessel limited motion at the first metatarsophalangeal joint, osteotomy,138 a dorsiflexory osteotomy at the base of the effect of varus rearfoot wedges in the management the proximal phalanx, is generally only used in younger of hallux limitus is unclear, with both increases128 patients or those with minimal degenerative changes and decreases129,130 in first metatarsophalangeal joint and is contraindicated in the presence of metatarsus motion reported while wearing such orthoses. primus elevatus. The Watermann osteotomy is a distal metatarsal osteotomy in which a dorsal wedge of bone Despite clinical reports of the efficacy of footwear is removed, resulting in a relative shortening of the modifications and foot orthoses for hallux limitus/ first metatarsal.139 However, for both these proce- rigidus,122,131 no controlled trials have so far been dures, only small-scale follow-up studies have been performed. However, it is likely that such interven- reported.139,140 tions would be more effective in less severe forms of the condition where there is still a reasonable amount The Youngswick procedure,141 a modification of the of available motion at the joint. Chevron bunionectomy, involves a V-shaped osteot- omy through the neck of the first metatarsal along Surgical with the removal of a rectangular piece of bone from the dorsal aspect of the metatarsal to enable the proxi- As with hallux valgus surgery, there have been a mul- moplantar displacement of the metatarsal head. Only titude of procedures described for the management two studies have reported outcomes of this procedure of hallux limitus/rigidus but few have been adequately – the original description of 10 cases141 and a 2-year evaluated or directly compared to each other. The follow-up of 17 cases by Bryant et al,142 who reported selection of procedure is heavily influenced by the significant increases in first metatarsophalangeal joint severity of the condition, so preoperative grading is dorsiflexion but no changes in plantar pressures considered essential. In mild cases, the aim of the beneath the hallux or first metatarsophalangeal surgery is to remove osteophytes and preserve joint joint. motion, whereas in advanced cases the aim is to block the residual motion that is causing the pain by fusing In more severe cases, joint destructive procedures the joint. The following section provides a brief over- are more frequently used. view of some of the more commonly performed pro- cedures for hallux limitus/rigidus; however, the The Keller procedure, which has already been reader should note that this coverage is by no means described in the previous section on hallux valgus comprehensive and several modifications of these (Fig. 8.3), has also been used with some success for techniques have been described in the literature. hallux limitus/rigidus. However, the Keller proce- dure is generally only indicated for people with limited The simplest joint preservation procedure, referred mobility and/or severe hallux limitus, as the propul- to as cheilectomy, involves removal of the dorsal exo- sive function of the hallux is impaired following the stosis from the metatarsal head and proximal phalanx, procedure.89 Furthermore, as with hallux valgus, the and debridement of the degenerative articular carti- Keller procedure is associated with a relatively high lage on the dorsal aspect of the joint (Fig. 8.17).93 rate of complications such as transfer lesions and/or Up to 30% of the metatarsal head is removed. This metatarsalgia, malunion and interphalangeal joint procedure is most appropriate for mild cases of hallux osteoarthritis.143 Finally, implant arthroplasty, which limitus/rigidus and results in significant increases in involves resecting a proximal portion of the proximal the dorsiflexion range of motion at the first metatar- phalanx, remodelling the metatarsal head and insert- sophalangeal joint.132 Several retrospective studies ing a silicone144,145 or metallic146 joint replacement, have reported high levels of patient satisfaction with has received considerable attention in the recent lit- the technique (72–90%), with the only consistent erature and appears to provide significant pain relief while keeping the joint mobile. Several studies have shown the technique to be useful in older patients.144,147

164 DISORDERS OF THE TOES A B C D E F Figure 8.17 Surgical procedures for hallux limitus/rigidus. A. Cheilectomy. B. Bonney-Kessel osteotomy. C. Watermann osteotomy. D. Youngswick procedure. E. Keller’s procedure. F. Implant arthroplasty. Silicone implants appear to have a higher failure rate that distraction resulted in an increase in osteoar- than metallic implants and are more likely to dislodge thritic changes in the interphalangeal joint.148 The and lead to foreign body reactions.146 second trial compared Keller’s arthroplasty to arthrod- esis in patients with hallux valgus or hallux rigidus and Only three randomised controlled trials have been found that the procedures produced similar out- conducted to assess the efficacy of surgical procedures comes.149 Finally, a well-designed trial comparing for hallux limitus/rigidus. The first evaluated the arthrodesis to implant arthroplasty reported better benefit of K-wire distraction when performing a outcomes in the arthrodesis group, due primarily to Keller’s arthroplasty but found that this modification the high rate of loosening of the phalangeal compo- conferred no additional advantages over the standard nent of the implant.150 surgical technique. In fact, there was some evidence

Lesser toe deformities 165 Overall, surgical treatment of hallux limitus/rigidus CLASSIFICATION AND does appear to be effective provided that extensive CLINICAL PRESENTATION presurgical planning is undertaken. However, as with surgery for hallux valgus, there is a need for direct There are several different types of lesser toe deformi- comparisons between different techniques with larger ties, which are classified according to the relative samples sizes and longer periods of follow-up. alignment of the metatarsophalangeal and interpha- langeal joints in the sagittal plane (Table 8.3). A LESSER TOE DEFORMITIES mallet toe is a fixed deformity in which the distal interphalangeal joint is plantarflexed. A hammer toe is Deformities of the lesser toes are among the most a deformity in which the proximal interphalangeal common of all foot disorders, affecting between 24% joint is plantarflexed and the metatarsophalangeal and 60% of older people.9,151–153 The Feet First study joint may be hyperextended. A claw toe is a deformity of 784 Americans aged over 65 years found that 35% in which the metatarsophalangeal joint is hyperex- of the sample had hammer toes, 33% had mallet toes tended and both the proximal and distal interphalan- and 9% had claw toes.9 Women are more likely to geal joints are plantarflexed. A retracted toe is a develop lesser toe deformities than men,9,10,30 which deformity in which the metatarsophalangeal joint so has been attributed to the influence of footwear with hyperextended that the apex of the toe is non-weight- a narrow toe-box.30,154,155 Older people with lesser toe bearing. The proximal and distal interphalangeal deformities are more likely to develop keratotic lesions joints may be neutral or plantarflexed.156,157 on the toes and plantar surface of the foot10 and have more difficulty performing balance and functional In the presence of hallux valgus, the second toe tasks requiring forward leaning.10 frequently develops a hammer toe deformity. In severe cases, the second toe may be forced dorsally or plan- tarly to accommodate the lateral displacement of the hallux. In this situation, the terms over-riding (or cross- Table 8.3 Classification of common lesser toe deformities in the sagittal plane Classification Appearance MPJ PIPJ DIPJ Typical lesion pattern Mallet toe Neutral Neutral Plantarflexed Apex of toe Hammer toe Neutral or Plantarflexed Neutral, Dorsum of PIPJ plantarflexed Plantar MPJ hyperextended or extended Claw toe Hyperextended Plantarflexed Plantarflexed Dorsum of PIPJ Dorsum of DIPJ Apex of toe Plantar MPJ Retracted toe Hyperextended Neutral or Neutral or Dorsum of PIPJ plantarflexed plantarflexed Plantar MPJ Apex of toe non- weightbearing DIPJ, distal interphalangeal joint; MPJ, metatarsophalangeal joint; PIPJ, proximal interphalangeal joint.

166 DISORDERS OF THE TOES AB CD Figure 8.18 Lesser toe deformities. A. Claw toes. B. Retracted toes. C. Under-riding toes. D. Over-riding toe. (A, courtesy of Lloyd Reed, Queensland University of Technology; B, courtesy of Felicity Prentice, La Trobe University; C, courtesy of Lesley Newcombe, La Trobe University.) over) or under-riding toe may be used to describe the clature is clinically useful, as treatment strategies will alignment of the second toe. Because of the subse- vary depending on the degree of correction that can quent subluxation of the second metatarsophalangeal be achieved. joint, the second toe may also be displaced in the transverse plane. Similar transverse plane displacement Older people with lesser toe deformities will fre- may accompany hammer or claw toe deformities of the quently present with complaints related to secondary third to fifth toes due to pressure from footwear, lesions (such as corns, calluses or ulcers) associated giving rise to adductovarus toe deformity. A range of with the toe deformity (see Table 8.3 for typical lesser toe deformities is shown in Figure 8.18. patterns of lesion location associated with each type of deformity). Toe deformities with a transverse plane Lesser toe deformities may be further classified component (particularly adductovarus of the fifth toe) according to the available motion in the affected are often associated with interdigital lesions or nail joints, using the terminology of flexible or rigid or, dystrophy due to compression against the adjacent alternatively, reducible or non-reducible. This nomen- toe. In severe cases with multiple toe involvement,

Lesser toe deformities 167 there may be evidence of a cautious gait pattern due Plantar pressure analysis may be useful to accu- to loss of the propulsive function of the toes.158,159 rately identify high pressure areas on the toes and to assess the efficacy of off-loading techniques. Claisse et AETIOLOGY al167 and Slater et al168 have recently demonstrated that modern plantar pressure systems have sufficient The aetiology of lesser toe deformities has not been spatial resolution to detect reductions in toe pressures thoroughly investigated and the evidence for many associated with prefabricated and custom-moulded proposed aetiological factors is derived largely from silicone toe orthoses in people with claw toes. clinical observations rather than case-control studies. Factors considered to be associated with the develop- TREATMENT ment of lesser toe deformities include ill-fitting foot- wear, 30,154,156abnormal foot posture (both pes planus51 Conservative and pes cavus160) and excessively long toes.161 The proposed association between ill-fitting footwear and Conservative treatment of lesser toe deformities lesser toe deformities was recently supported by Menz involves addressing the associated nail and skin con- & Morris,30 who assessed footwear characteristics in ditions, footwear advice and/or modification, and 176 older people and found that those with lesser toe orthodigital techniques. In cases where it is clear that deformities were two to four times more likely to wear ill-fitting footwear is the underlying cause (or an shoes substantially shorter than their foot. Over time, aggravating factor), the older person should be advised it is likely that the toes adapt to the limited area avail- to purchase more appropriately fitting footwear with able in the toe box of the shoe via hyperextension of a broad and deep toe-box. If this is not possible for the metatarsophalangeal joints and plantarflexion of financial or other reasons, shoe stretching or balloon- the proximal interphalangeal joint.156 Lesser toe patching may be an appropriate alternative. Orthodig- deformities also frequently develop in conjunction ital techniques can be very effective in redistributing with systemic conditions such as diabetes mellitus,162 load away from painful areas and may also play a role rheumatoid arthritis163 and Charcot–Marie–Tooth in the non-surgical correction of flexible toe deformi- disease164 and may also develop following cerebrovas- ties.169 Each of these interventions is discussed in cular accident (stroke).165 more detail in Chapter 11. However, despite anec- dotal reports of effectiveness, no controlled trials ASSESSMENT AND DIAGNOSIS of these conservative techniques have so far been undertaken. Lesser toe deformities can be easily diagnosed via visual observation and physical examination. The foot Surgical should be observed both non-weightbearing and weightbearing, and passive range of motion tests for As with deformities of the first toe, several surgical each joint should be undertaken in order to ascertain procedures and modifications have been developed the degree to which the deformity is reducible. Sec- for the management of lesser toe deformities. A brief ondary lesions associated with the deformity should summary is provided in the following section but for be carefully inspected and documented. Evaluation of further information the reader is directed to a recent footwear (described in Chapter 3) is essential to assist comprehensive review by Coughlin.157 in determining the underlying cause of the deformity and the suitability of the shoe to accommodate toe The selection of surgical procedure for the correc- splinting devices.166 tion of lesser toe deformities is highly dependent on the available motion in the interphalangeal joints. Radiographic assessment is not required to diag- Generally speaking, rigid deformities require arthro- nose lesser toe deformity but is necessary for presurgi- plasty, whereas flexible deformities can be corrected cal planning. Dorsoplantar projections will enable the with soft tissue surgical techniques such as tendon accurate identification of excessively long metatarsals lengthening and transfer.157 For the mallet toe, an by documenting the metatarsal formula. Lateral pro- elliptical incision is made over the distal interphalan- jections may enable the visualisation of severe hammer geal joint and deepened through the joint capsule and and claw toes; however, in this view all toes are super- extensor tendon. The collateral ligaments are severed imposed, which makes accurate measurement quite and the distal portion of the intermediate phalanx is difficult. removed. If the deformity is severe, the flexor tendon

168 DISORDERS OF THE TOES may also be severed. The toe is then stabilised with a should be advised that the ability to flex the toes is K-wire and taped into the corrected position. The lost following the surgery. wire is removed after a period of 3 weeks. The surgical procedure is essentially the same for hammer toes Fifth toe deformities frequently have a transverse (with the exception that the procedure is directed to and frontal plane component, because of their suscep- the proximal interphalangeal joint) and for claw toes tibility to pressure from footwear. For this reason, (with the exception that both the proximal and distal several different surgical techniques have been devel- interphalangeal joints are corrected). Although some oped specifically for the fifth toe. Overriding fifth toes authors recommend that peg-in-hole arthrodesis also can be managed with soft tissue release or, in more be performed,170 Coughlin157 suggests that arthrode- advanced cases, transfer of the extensor digitorum sis may occur naturally and is not necessary for a suc- longus tendon. This procedure, first described by cessful result to be achieved. Case series studies Lapidus,176 involves releasing the tendon 4 cm proxi- indicate that patient satisfaction with these procedures mal to the metatarsophalangeal joint, then threading is generally high. Dissatisfaction with the surgical the distal portion around the proximal phalanx to the result is most commonly due to residual stiffness of lateral plantar aspect of the toe. Here, the tendon is the toes, recurrent deformity, malalignment and dif- sutured to the tendon of abductor digiti minimi. An ficulty with footwear.170 alternative procedure is to remove the proximal phalanx and syndactylise the fourth and fifth toes.177 Amputation of the second toe for the management Both procedures have reportedly high success rates, of severe crossover or hammer toe deformity has been with recurrence of the deformity estimated to occur recommended in older people for whom the recovery in less than 10% of cases.157 Syndactylisation, however, period of corrective surgery may be too debilitat- may not be cosmetically acceptable for some patients. ing.171,172 Sundaram & Walsh171 performed seven cases Underriding fifth toes are less common but can be of second toe amputation in people aged over 70 corrected by extensor digitorum longus tendon release years and reported that all were satisfied with the and excision of the proximal phalanx. outcome. Similar results were reported by Gallentine & DeOrio172 in 13 patients (aged 72–86 years) who LESS COMMON DISORDERS had undergone second toe amputation for severe AFFECTING THE TOES hammer toe. However, this procedure needs to be carefully considered, as the postoperative cosmetic TAILOR’S BUNION appearance may be troubling for some people. Fur- thermore, the space created by the absence of the Tailor’s bunion, also referred to as bunionette, is an second toe may increase any pre-existing valgus defor- enlargement of the lateral aspect of the fifth metatarsal mity of the hallux. Indeed, of the 20 cases reported head (Fig. 8.19). The condition was originally in these two studies, 10 demonstrated valgus drift of the hallux following the procedure. Figure 8.19 Tailor’s bunion. (Courtesy of Lesley Newcombe, La Trobe University.) Surgical management of flexible lesser toe deformi- ties involves tendon lengthening and/or transfer techniques. For retracted toes, a dorsal incision is made over the proximal interphalangeal joint and a Z-plasty tendon lengthening procedure is performed on the extensor digitorum longus tendon. For flexible hammer and claw toes, a flexor digitorum longus transfer (also referred to as the Girdlestone–Taylor procedure) is commonly used.173 This involves detach- ing the flexor digitorum longus tendon from the base of the distal phalanx, splitting it longitudinally and transferring each segment around the proximal phalanx and suturing it to the extensor hood. Patient satisfaction with this procedure has been reported to range from 54% to 90%.173–175 Few complications have been associated with the technique; however, patients

Less common disorders affecting the toes 169 observed in tailors and was thought to be caused by Figure 8.20 Hallux varus. (Courtesy of Matthew Dilnot, long periods sitting cross-legged with the lateral Melbourne Foot Clinic.) border of the foot compressed against the floor.178 As with hallux valgus, longstanding cases may develop aged over 65 years, with men being affected two to a large, painful osseous prominence associated with six times more frequently than women.183 Risk factors an overlying adventitious bursa. Few epidemiological for the development of gout include alcohol con- studies have documented the presence of tailor’s sumption (particularly beer), renal insufficiency, bunions, however, the Feet First study, which involved diuretic use, dehydration, increased body mass index 784 people aged over 65, reported a 13% prevalence and dietary factors (including increased meat and of ‘bunionette’, with equal distribution across men seafood consumption, and decreased dairy consump- and women.9 Postulated aetiological factors for tai- tion).184–187 The underlying pathophysiology of gout lor’s bunion include incomplete development of the relates primarily to elevated blood levels of urate, a transverse intermetatarsal ligament, increased inter- byproduct of purine metabolism. Normally, serum metatarsal angles associated with a broad forefoot, urate levels are between 2 and 8 mg/100 ml. and congenital dumbbell-shaped fifth metatarsal However, in the presence of either overproduction of head.179 However, no detailed case-control studies urate or, more commonly, impaired secretion of have been undertaken. Conservative treatment of tai- urate, monosodium urate crystals form and are depos- lor’s bunion involves addressing secondary skin ited in the peripheral joints, resulting in acute inflam- lesions, advising the patient to purchase broader foot- matory arthritis.187 wear, and the use of felt or silicone padding tech- niques to redistribute pressure away from the lateral Acute gout initially affects the first metatarsopha- eminence. Surgical management ranges from simple langeal joint in 50% of cases and approximately 90% of exostectomy to the use of distal osteotomies similar patients will develop this manifestation at some point to those used for hallux valgus.179 during the disease.188 The reason for this predilection is unclear; however, it has been hypothesised that the HALLUX VARUS first metatarsophalangeal joint has a relatively low tem- perature, low pH and is subject to large compressive Hallux varus is an uncommon condition in which the forces when walking; factors that may accelerate the hallux is adducted relative to the first metatarsal (Fig. 8.20). Although congenital forms of the condition do occur in conjunction with teratogenic anomalies, the most commonly encountered cause of hallux varus in older people is surgical overcorrection of hallux valgus deformity. Initial reports of iatrogenic hallux varus were attributed to surgical techniques advocating excision of the lateral sesamoid;2 however, it is now recognised that most hallux valgus procedures can potentially lead to hallux varus.180 Because of the increased breadth of the forefoot, patients will have great difficulty finding suitable footwear and are likely to develop keratotic lesions on the medial aspect of the hallux. Conservative treatments, such as splinting and strapping techniques, are generally of little use, so most cases will require revisional surgery. Several techniques have been described, which are essentially mirror images of hallux valgus procedures.181,182 GOUTY ARTHRITIS Gout is the most common inflammatory arthritis in older people, affecting approximately 3% of people

170 DISORDERS OF THE TOES Figure 8.21 Tophaceous deposits associated with chronic gouty arthritis. A. Distal interphalangeal joint of the third toe. B. Fifth metatarsophalangeal joint. (Courtesy of Lesley Newcombe, La Trobe University.) AB formation of monosodium urate crystals.189 Acute Treatment of acute gout involves administration gout affecting the first metatarsophalangeal joint, often of colchicine (a potent anti-inflammatory drug), referred to as podagra, has a sudden onset and is non-steroidal anti-inflammatory drugs (NSAIDs) or exquisitely painful, and may last from a few days to corticosteroid (either orally or via intra-articular injec- several weeks. Other joints that are commonly affected tion).192 A recent systematic review indicated that, while by acute gout include the metatarsophalangeal joints, colchicine is effective, high levels of gastrointestinal tox- the ankle and the knee. If left untreated, approximately icity associated with the drug limit its use in older 75% of patients will develop chronic tophaceous gout, patients and, therefore, NSAIDs or corticosteroids characterised by the formation of solid urate deposits should be the first line of treatment.193 Management of (called tophi) in the connective tissues, most com- chronic gout involves counselling the patient with monly the feet, fingers, elbows and ears (Fig. 8.21).190 regard to weight loss, alcohol consumption and diet, Older women are more likely to develop tophaceous and adjusting medications that contribute to hyperuri- gout early in the disease process, possibly because of caemia.194 Allopurinol, a xanthine oxidase inhibitor, has their higher prevalence of diuretic use.191 been shown to significantly reduce urate levels and is therefore considered to be an effective drug for prevent- Diagnosis of gout is confirmed by the microscopic ing recurrent gout.192 Prominences caused by topha- observation of urate crystals in synovial fluid, bursae ceous deposits will also need to be managed with or tophi; however, clinical criteria are sufficient to footwear modifications and/or orthoses. reach a provisional diagnosis. These criteria include unilateral synovitis of the first metatarsophalangeal SUMMARY joint with maximum inflammation within 24 hours, no evidence of infection, a history of recurrent epi- An overview of the most common toe deformities sodes of monoarticular arthritis followed by complete affecting the older foot has been presented. Conserva- resolution, observation of subcortical bone cysts from tive management plays an important role in reducing radiographs, and rapid resolution of inflammation fol- the pain associated with secondary lesions caused by lowing administration of colchicine.187 Differential these deformities, and in some cases soft tissue cor- diagnoses include osteoarthritis, rheumatoid arthritis rection may be possible with orthodigital techniques. and septic arthritis. Pseudogout, a condition caused by Many older patients, however, will require surgical deposition of calcium pyrophosphate crystals within correction in order to remain pain-free. Because of joints, has a similar clinical presentation to gout but the wide range of surgical options available for the most commonly affects the knee, wrist or shoulder. correction of toe deformities, thorough presurgical Accurate differentiation between gout and pseudo- planning is required to achieve optimum results. gout requires microscopic examination of synovial fluid.186

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References 177 present status. Arthritis and Rheumatism 1973; 16: 193. Schlesinger N, Schumacher R, Catton M et al. Col- 431–435. chicine for acute gout. Cochrane Database of 191. MacFarlane DG, Dieppe PA. Diuretic-induced gout Systematic Reviews 2006; CD 006190. in elderly women. British Journal of Rheumatology 1985; 24: 155–157. 194. Zhang W, Doherty M, Bardin T et al. EULAR evi- 192. Sutaria S, Katbamna R, Underwood M. Effective- dence based recommendations for gout. Part II: ness of interventions for the treatment of acute and Management. Report of a task force of the EULAR prevention of recurrent gout – a systematic review. Standing Committee for International Clinical Rheumatology 2006; 45: 1422–1431. Studies Including Therapeutics (ESCISIT). Annals of the Rheumatic Diseases 2006; 65: 1312–1324.

Disorders of the forefoot CHAPTER 9 CHAPTER CONTENTS DEFINITION, PREVALENCE AND CLASSIFICATION Definition, prevalence and classification 179 The term metatarsalgia literally means pain in the Diagnosis 180 metatarsal region of the foot and thus describes a symptom rather than a specific clinical entity.1,2 Estab- Common causes of forefoot pain in older lishing the prevalence of metatarsalgia is therefore people 181 very difficult. While prevalence rates of up to 65% Intermetatarsal neuroma 182 have been reported for conditions of pain in the fore- Predislocation syndrome 184 foot (such as plantar calluses, hallux valgus and hallux Insufficiency fractures of the metatarsals 186 limitus/rigidus), this is likely to be an overestimate of the prevalence of metatarsalgia, as these conditions Summary 186 are not always symptomatic. Unfortunately, few References 187 studies have directly addressed the prevalence of site- specific foot pain. The Feet First study of 784 Ameri- cans aged over 65 years reported that 20% of the sample exhibited tenderness to palpation in the meta- tarsal head region, with equal sex distribution.3 More recently, Menz et al4 reported that 36% of 301 people aged over 75 years had disabling foot pain and of these 70% reported pain in the forefoot, which equates to a similar prevalence of forefoot pain (approximately 25%). Several authors have attempted to classify metatar- salgia according to the underlying causes. Thomas et al5 proposed three types: primary metatarsalgia (caused by plantar keratoses, hallux valgus and hallux limitus/rigidus), secondary metatarsalgia (pain in the forefoot due to systemic disease) and metatarsalgia unrelated to weight distribution (including tarsal tunnel syndrome and vascular disease). Regnauld6 proposed four categories: diffuse metatarsalgia (caused by acquired mechanical/overuse disorders), localised metatarsalgia (caused by excessively long or

180 DISORDERS OF THE FOREFOOT large metatarsals), subcutaneous soft tissue metatarsal- with metatarsalgia and 50 controls revealed that the gia (caused by intermetatarsal neuroma, bursitis and most commonly observed finding in those with meta- cysts) and cutaneous metatarsalgia (caused by plantar tarsalgia was intermetatarsal bursitis (21%), followed keratoses, verrucae or ulcers). Scranton7 proposed by intermetatarsal neuroma (15%) and effusion of the three categories: primary metatarsalgia (caused by metatarsophalangeal joints (12%).14 hallux valgus, hallux limitus/rigidus or long first metatarsal), secondary metatarsalgia (caused by sys- DIAGNOSIS temic conditions such as rheumatoid arthritis and gout, in addition to ‘local’ disorders such as stress Because of the large number of conditions that may fractures and sesamoiditis) and pain under the forefoot result in forefoot pain, diagnosing the underlying (caused by intermetatarsal neuroma, verrucae or tarsal cause can be challenging, particularly when multiple tunnel syndrome). Finally, Dockery8 proposed three causes may coexist. A simple clinical algorithm categories: primary metatarsalgia (including condi- involving a process of elimination, based on a system tions related to abnormal anatomy of the metatarsals), described by Coughlin,15 is shown in Table 9.1. The secondary metatarsalgia (such as Morton’s neuroma, first step is to ascertain whether the pain is associated tarsal tunnel syndrome and forefoot pain secondary with a plantar keratotic lesion or verruca over the to systemic conditions) and iatrogenic metatarsalgia symptomatic site. Once this simple cause has been (most commonly as a result of osteotomy ruled out, systemic conditions that commonly result procedures). in forefoot pain, such as rheumatoid arthritis, osteo- arthritis or gout, need to be considered, as joint Classification of metatarsalgia is clearly problematic degeneration or effusions associated with these condi- and it is questionable whether such categorisation tions can lead to forefoot symptoms (Table 9.2). provides any clinical benefits or assists in diagnosis. However, what is clear from these classification Having ruled out a systemic cause, further detail systems is that pain in the forefoot may result from a regarding the nature of the symptoms should be myriad of causes, from localised skin, soft tissue or sought, as neuritic symptoms (such as tingling, pins osseous pathology through to systemic conditions and needles, and referred pain into the toes) may manifesting in the foot. Risk factors for the develop- indicate an intermetatarsal neuroma. This provisional ment of metatarsalgia therefore depend on the under- diagnosis can be further explored using Mulder’s click lying condition that may be giving rise to forefoot test and ultrasound imaging (this is discussed later in symptoms. Nevertheless, Waldecker9,10 has recently the chapter). In the absence of neuritic symptoms, conducted two case-control studies of unspecified predislocation syndrome or insufficiency fractures of metatarsalgia, based on the premise that anatomical the metatarsals may need to be considered. Although and mechanical factors may be responsible for diffuse the nature of the pain associated with predislocation forefoot pain in the absence of other observable dis- syndrome can sometimes be vague, pain on plan- orders. The first study revealed no difference in ultra- tarflexion and the tendency of the proximal phalanx sonically measured plantar fat pad thickness between to sublux when dorsal translation is applied are char- cases and controls;9 however, the second study indi- acteristic signs. Pain resulting from insufficiency frac- cated that participants with hallux valgus and forefoot tures can be difficult to delineate from predislocation symptoms demonstrated increased plantar loading of syndrome, so a definitive diagnosis may require bone the lateral metatarsal heads during gait.10 Over time, scanning. increased vertical loading may cause damage to plantar soft tissues, and there is also some evidence that This simple algorithm will assist in the diagnosis of increased plantar pressures may lead to a correspond- the most common causes of forefoot pain in older ing increase in pressure in the intermetatarsal spaces.11 people; however, it needs to be kept in mind that a Hsu et al12 and Wang et al13 have demonstrated that strict process of elimination is not always possible, as plantar soft tissues in older people demonstrate greater several conditions may coexist. Furthermore, if all stiffness and dissipate more energy when compressed; these common diagnoses are ruled out, more exten- however, the relationship between these changes and sive diagnostic imaging, including magnetic resonance the development of symptoms has not yet been imaging, may be required to diagnose less commonly confirmed. encountered causes of forefoot pain, such as various soft tissue and bony tumours, infection and foreign Ultrasound imaging has shed further light on the bodies. possible causes of forefoot pain. A study of 112 people

Common causes of forefoot pain in older people 181 Table 9.1 Clinical algorithm for the step-wise diagnosis of forefoot pain Clinical observation If yes, may indicate . . . If no . . . 1. Is there a plantar keratotic Painful plantar keratosis or verruca Go to 2 lesion or verrucae present? Go to 3 Forefoot pain secondary to joint 2. Does the patient have a systemic degeneration/synovitis. May require Go to 4 condition that may lead to confirmation with plain film X-ray forefoot pain (e.g. rheumatoid Go to 5 arthritis, osteoarthritis, gout)? Suspect intermetatarsal neuroma. Perform Mulder’s click test and Consider less common causes and 3. Does the patient report neuritic confirm diagnosis with ultrasound refer for more extensive symptoms (tingling, referred Predislocation syndrome diagnostic imaging pain, pins and needles)? Suspect insufficiency fracture. Confirm 4. Is there pain slightly distal to with X-ray or bone scan the metatarsal head, at end range of plantarflexion or when the proximal phalanx is translated dorsally? 5. Is there localised pain on direct palpation of the metatarsal head or slightly proximal to it? Table 9.2 Systemic conditions that may cause forefoot pain in older people Condition Mechanism Osteoarthritis Cartilage degeneration, joint space narrowing and formation of osteophytes affecting the Rheumatoid arthritis metatarsophalangeal joints Gout Synovitis of the metatarsophalangeal joints Development of hallux valgus Psoriatic arthritis Development of retracted toes Paget’s disease Distal displacement of plantar fibro-fatty padding Development of rheumatoid nodules under metatarsal heads Acute: inflammation of the metatarsophalangeal joints due to deposition of monosodium urate crystals Chronic: joint degeneration and formation of tophaceous deposits in joints and tendon sheaths Synovitis and enthesitis of metatarsophalangeal joints Bone pain as a result of increased vascularity and articular distortion COMMON CAUSES OF FOREFOOT intermetatarsal neuroma and predislocation syndrome. PAIN IN OLDER PEOPLE Insufficiency stress fractures of the metatarsals are only occasionally cited as a cause of forefoot pain in The most common cause of forefoot pain in older older people; however, they are likely to be more people is the presence of plantar keratotic lesions, prevalent than is commonly recognised, because of which are discussed in detail in Chapter 4. Other misdiagnosis. Other conditions associated with fore- commonly observed conditions in older people are foot pain, such as Freiberg’s infraction and sesamoid-

182 DISORDERS OF THE FOREFOOT itis, are most commonly diagnosed in younger people A and are therefore not discussed in this chapter. INTERMETATARSAL NEUROMA B Aetiology and clinical presentation Figure 9.1 Clinical tests for assessing intermetatarsal neuroma. A. Forefoot squeeze (Mulder’s click). Intermetatarsal neuroma, also referred to as plantar B. Webspace squeeze. digital neuroma, was first described by Lewis Dur- lacher in 1845 but is frequently attributed to Dudley However, this test is not highly specific, particularly Morton, who reported 11 cases in 1876.16 Conse- in milder forms of the condition with less pronounced quently, the condition is also referred to as Morton’s hypertrophy of the nerve. Ultrasound imaging is con- neuroma or Morton’s metatarsalgia. The classical pre- sidered to be the most appropriate diagnostic modal- sentation is that of severe, neuritic pain in the third ity, with sensitivities and specificities of between 85% or fourth intermetatarsal space that radiates towards and 100% when compared to intraoperative findings the toes, exacerbated by long periods of weightbear- or postsurgical histopathology.25–32 Under ultrasound ing and alleviated by rest or removal of footwear.15,17 imaging, neuromas appear as elliptical hypoechogenic Factors thought to be associated with intermetatarsal structures running parallel to the metatarsals that are neuroma include female sex, increased body mass integrated with surrounding nerve tissue. A transverse index, reduced space between the metatarsals, exces- plantar scan is considered to be more accurate than a sive foot pronation, elevated plantar pressures and the dorsal approach because of improved coupling; wearing of tightly fitting shoes;15,17–19 however, none however, a dorsal scan is sometimes necessary of these proposed risk factors has been confirmed by when the plantar scan is negative.20 Although not as case-control studies. Indeed, a recent case-control widely accessible, magnetic resonance imaging has study by Betts et al20 found no difference in ultrasoni- also been used for the diagnosis of intermetatarsal cally-measured intermetatarsal space or plantar neuroma, with similar sensitivity and specificity to pressures in 242 patients with neuroma symptoms ultrasound.33 compared to 35 controls. The pathology of intermetatarsal neuroma is still uncertain but is thought to consist of neural fibrosis, oedema, demyelination and degeneration of the inter- metatarsal nerve.17 However, histological comparison studies by Morscher et al21 and Bourke et al22 found no significant differences between cases and controls, with the exception of a higher proportion of cases exhibiting demyelination. Similarly, a magnetic reso- nance imaging study recently reported that, while slightly larger nerve lesions were observed in people with symptoms of intermetatarsal neuroma, there was a significant overlap between cases and controls.23 These findings suggest that degenerative changes in intermetatarsal nerves may be more common than previously thought and are not necessarily associated with neuroma symptoms. The diagnosis of intermetatarsal neuroma is based on a combination of presenting symptoms, physical examination and diagnostic imaging. Compression of the affected intermetatarsal space may reproduce the symptoms and cause a palpable ‘click’ as the neuroma is subluxed beneath the transverse metatarsal ligament (referred to as Mulder’s click test; Fig. 9.1).24

Common causes of forefoot pain in older people 183 AB has been also associated with adverse reactions such as plantar fat pad atrophy44,45 and skin hyperpigmenta- Figure 9.2 Padding techniques for intermetatarsal tion.45 It would therefore appear that corticosteroid neuroma. A. Plantar metatarsal pad/metatarsal dome. injection may be useful temporary measure but cannot B. Pad to elevate fourth and fifth metatarsal heads. be considered an effective long-term strategy for the treatment of intermetatarsal neuroma. Conservative treatment Intralesional injection of sclerosing agent has been Conservative treatment of intermetatarsal neuroma recommended by several authors. An uncontrolled involves changing footwear to shoes with a lower study of 100 patients by Dockery reported an 89% heel and broader forefoot, pressure redistribution success rate with three to seven injections of a 1 ml using plantar padding techniques,19 foot orthoses34 4% alcohol solution every 5–10 days, with 82% report- and intralesional injections of cortisone35,36 or scleros- ing complete resolution of symptoms.37 Fanucci et al38 ing agents.37–39 Retrospective studies suggest that, reported that ultrasound-guided injection of an anaes- overall, conservative management is effective in at least thetic and ethylic alcohol preparation achieved total 50% of cases.15,40 The most effective form of padding or partial symptomatic relief in 40 patients after 10 appears to be the plantar metatarsal pad (also called a months of follow-up. More recently, Hyer et al39 metatarsal dome), placed proximally to the second reported that, after 1 year of follow-up, five out of six to fourth metatarsal heads (Fig. 9.2A). This pad is patients achieved significant pain relief with a weekly thought to achieve pain relief by slightly elevating and series of three to nine injections of a 1 ml 4% alcohol spreading the central metatarsals, thereby increasing solution. the intermetatarsal space and decreasing pressure on the neuroma itself.41 Plantar pressure studies have Although these results are promising, larger studies confirmed that this style of pad significantly reduces with a control group are required to confirm the effi- forefoot pressures42,43 and is more effective than aper- cacy of conservative treatments. Indeed, the recent tured pads.43 Hirschberg34 has also claimed clinical Cochrane review of interventions for intermetatarsal success using a technique in which the fourth and fifth neuroma18 found only one controlled trial of conser- metatarsal heads are elevated by gluing a small lift vative treatment – a study of 23 people who received under the insole of the shoe (Fig. 9.2B). either a supinatory or pronatory orthosis (manufac- tured from compressed felt) which reported no dif- Intralesional injection of corticosteroid has quite ferences in reported pain levels between the two variable success rates in the literature. While Green- groups.46 Clearly, there is a need for more rigorous field et al35 reported that 80% of patients reported at evaluation of both orthotic therapy and injection least partial relief of symptoms following corticoste- therapy in the treatment of intermetatarsal neuroma. roid injection, a retrospective study of 115 patients by Bennett et al40 reported a much lower success rate Surgical treatment (47%). Rasmussen et al36 found that while 80% of 43 patients who received a single corticosteroid injection Surgical removal of intermetatarsal neuroma can be obtained short-term symptomatic relief, at the 4-year conducted under general, regional or even local follow-up period, approximately half were still symp- anaesthesia and involves the resection of the affected tomatic or had selected to undergo surgery. Repeated nerve through a plantar, dorsal or web space incision. corticosteroid injection for intermetatarsal neuroma The most commonly used approach is through the dorsum of the foot, as this allows for earlier post- operative ambulation and does not result in plantar scarring. However, the disadvantage of this approach is that the deep transverse intermetatarsal ligament must be severed during the procedure and there is a greater chance of postoperative dead space and sub- sequent infection.47 The efficacy of neuroma surgery has not been thoroughly evaluated; however, case series studies indicate that up to 24% of patients have unsatisfactory results.48–50 Adverse effects of neuroma surgery are

184 DISORDERS OF THE FOREFOOT relatively common, including haematoma formation A in the intermetatarsal space, ischaemia of the toes due to postoperative oedema and, the most troublesome complication, formation of a stump neuroma with symptomatic recurrence that often requires revisional surgery.47 Surgery appears to be more successful when only one neuroma requires excision.50 The Cochrane review of treatments for intermeta- tarsal neuroma18 found only two randomised trials of surgical intervention. The first, a comparison of plantar and dorsal incision techniques,51 found that the efficacy of the techniques was similar; however, the dorsal approach resulted in less symptomatic postoperative scarring. The second study compared neuroma resection versus a technique in which the interdigital nerve is transposed into the intermuscular space between the adductor hallucis and interossei muscles.52 Patients who had undergone the intermus- cular transposition technique were more likely to achieve at least 50% relief of pain compared to those who had the neuroma resected. The review, however, concluded that there is currently insufficient evidence upon which to adequately assess the efficacy of surgi- cal treatments for intermetatarsal neuroma. PREDISLOCATION SYNDROME B Figure 9.3A, B Early stage predislocation syndrome/ Aetiology and clinical presentation plantar plate rupture. Note the dorsiflexion and displacement of the second toe, with corresponding Forefoot pain associated with instability of the meta- increase in second interspace. (Courtesy of Matthew tarsophalangeal joints is a common clinical finding Dilnot, Melbourne Foot Clinic.) that has been described under several different titles in the podiatric and orthopaedic literature, including overly long metatarsal60 and the wearing of high- metatarsophalangeal joint instability,53 monoarticular heeled footwear.60 However, Yu et al57 suggest that non-traumatic synovitis,54 metatarsophalangeal joint the absence of these factors does not necessarily pre- subluxation,55 plantar plate rupture56 and, most clude a diagnosis. recently, predislocation syndrome.57 Because the fea- tures of each of these conditions overlap and no diag- The classical presentation of predislocation syn- nostic criteria have yet been developed, the term drome is that of a focal, ‘bruise-like’ or throbbing predislocation syndrome is probably the most appropri- pain on the plantar aspect of the joint that is exacer- ate terminology. The syndrome is characterised by bated by long periods of weightbearing activity. No a progressive, dorsal subluxation of the proximal plantar keratotic lesions are generally present, although phalanx on the metatarsal head that is thought to there may be some swelling evident and an associated occur in response to a gradual weakening, inflamma- widening of the interspace (Fig. 9.3). Significant tion and eventual rupture of the plantar plate. The transverse plane deviation of the toe occasionally second metatarsophalangeal joint is considered to be occurs in advanced cases, which may indicate concur- the most common site, although any of the lesser metatarsophalangeal joints may be affected.58 Although no case-control studies have been undertaken, case series studies and clinical observations suggest that the syndrome is associated with hallux valgus,53,59 an

Common causes of forefoot pain in older people 185 Figure 9.5 Draw test for the assessment of predislocation syndrome. Figure 9.4 Stage 3 predislocation syndrome, with the proximal phalanx of the second toe lying in a fixed, dislocated position with transverse plane malalignment. (Courtesy of Lesley Newcombe, La Trobe University.) rent rupture of the collateral ligament (Fig. 9.4).61 Figure 9.6 Taping technique for predislocation Direct palpation just distal to the metatarsal head will syndrome. The proximal phalanx is held in a plantar elicit symptoms, as will plantarflexion of the joint to position by adhesive tape, thereby reducing tension on end range of motion. Thompson & Hamilton59 have the plantar plate. also described a clinical test in which the metatarsal head is stabilised with the thumb and index finger and taping and splinting techniques to prevent further a vertical, translational thrust is applied to the proxi- progression. Felt or foam padding placed under the mal phalanx with the contralateral hand (Fig. 9.5). affected metatarsal head will assist in elevating it rela- The test result is then used to classify the severity of tive to the proximal phalanx, which may reduce the condition using the following scoring system: 0 tension on the plantar plate.56 Crossover taping, in (no dorsal translocation occurs), 1 (the phalanx sub- which the proximal phalanx is translated plantarly luxes dorsally), 2 (the phalanx can be dislocated from (Fig. 9.6), may achieve the same effect, although the the metatarsal head but manually reduced) and 3 (the need to frequently remove and reapply the tape makes phalanx lies in a fixed dislocated position). it an impractical long term strategy.56,57 Predislocation syndrome can be differentiated from Few studies have been undertaken to assess the other causes of metatarsalgia by the absence of kera- efficacy of conservative management of predisloca- totic lesions, neuritic symptoms or significant plain tion syndrome. Mizel & Michelson63 reported a 70% film X-ray findings. Bone scans may show increased success rate with intra-articular corticosteroid injec- localised uptake in the affected metatarsal head, while tion and prescription of rigid shank footwear. Simi- plantar plate rupture and synovitis of the flexor tendon larly, Trepman & Yeo64 reported a 60% rate with sheath are readily observable with magnetic resonance steroid injection and the prescription of rocker sole imaging.62 shoes. In contrast to these two studies, Mann & Mizel54 reported that only one of seven patients with Conservative treatment Conservative management of predislocation syndrome involves pain relief (using corticosteroids or non- steroidal anti-inflammatory medications), redistribu- tion of pressure away from the affected site, and

186 DISORDERS OF THE FOREFOOT metatarsophalangeal joint synovitis responded to pain in older people. Clinically, these fractures present anti-inflammatory medications and extra-depth shoes, as an acute, focal area of tenderness directly under (or with the remainder eventually requiring surgery. Vari- slightly proximal to) the affected metatarsal head, with ation in the severity of the condition may explain or without swelling. In contrast to fatigue fractures, these disparate findings;57 however, controlled trials insufficiency fractures develop in response to routine are required to adequately determine the efficacy of daily activities and are rarely precipitated by periods these approaches. of strenuous activity.72 The most common site is the second metatarsal, which experiences considerably Surgical treatment greater strain during gait.76 Although few detailed studies have been undertaken, factors thought to Surgical management of predislocation syndrome be associated with metatarsal insufficiency fractures involves restoring normal plantar plate function by include overly long or short metatarsals, lateral meta- the release of soft tissue contractures, tendon transfer tarsal overload associated with hallux valgus, and the and lesser metatarsal osteotomy.55,57,59,65,66 These wearing of high-heeled shoes.72,77 Insufficiency frac- procedures are essentially modifications of techniques tures should also be suspected in older people present- used to correct lesser toe deformities and are more ing with transfer metatarsalgia following foot surgery, fully discussed in Chapter 7. Combined soft tissue and as several cases following Keller’s bunionectomy have osseous techniques have been recommended by Daly been reported.78–80 & Johnson,65 who described a technique involving partial proximal phalanx excision and syndactyly of Dorsoplantar plain film X-rays may reveal a small the toes, and Yu and colleagues,57 who advocated transverse crack accompanied by subchondral sclerosis extensor hood and joint capsule release, arthrodesis of the metatarsal head; however, this can be easily of the proximal interphalangeal joint, and transfer of missed and may not be visible for 2–3 weeks after the the flexor digitorum longus tendon by threading it onset of symptoms.67,81 Bone scans are substantially dorsally through a drill hole in the metatarsal head more sensitive and will reveal increased uptake in the and securing to the dorsal periosteum. Although no metatarsal head as early as 3 days after symptoms large-scale, controlled studies have been undertaken, develop.72,73 surgical management has been reported to result in high levels of satisfaction in only 38–64% of Treatment patients,65,66 suggesting considerable room for improvement in surgical techniques. Treatment of insufficiency fractures involves offload- ing the affected site until the bone has sufficient time INSUFFICIENCY FRACTURES to heal. This may involve bed rest, use of crutches, OF THE METATARSALS various padding techniques to offload the metatarsal head, non-forefoot-loading surgical boots or below Aetiology and clinical presentation knee plaster casts.72,74 Complete healing generally takes 6–8 weeks. Optimising the management of pre- Stress fractures develop when repetitive loads applied existing conditions that may result in osteopenia (such to bone exceed the level of mechanical resistance. as osteoporosis, hyperparathyroidism and rheumatoid There are two types of stress fracture: fatigue frac- arthritis) is an important component of insufficiency tures, which result from excessive loads applied to fracture treatment. Furthermore, older patients diag- normal bone (commonly observed in military recruits), nosed with insufficiency fractures without a history of and insufficiency fractures, which result from normal osteoporosis should also be referred for bone density or slightly elevated loads applied to bone with low assessment. mechanical resistance.67,68 Insufficiency fractures are most commonly diagnosed in older women, who SUMMARY experience a rapid loss in bone density (approximately 10% per decade) from the onset of menopause.69 Forefoot pain is common in older people and may result from a combination of local and systemic condi- Although they are frequently overlooked,70 insuffi- tions. The non-specific term metatarsalgia should not ciency fractures can develop in the metatarsals71–75 and be considered an adequate diagnosis, as there are few need to be considered as a potential cause of forefoot

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188 DISORDERS OF THE FOREFOOT 29. Jones S, Bygrave CJ, Bettes RP et al. Morton’s 45. Reddy PD, Zelicof SB, Ruotolo C et al. Interdigital neuroma: a sonographic-surgical evaluation. The Foot neuroma. Local cutaneous changes after corticoste- 1999; 9: 189–192. roid injection. Clinical Orthopaedics and Related Research 1995; 317: 185–187. 30. Read JW, Noakes JB, Kerr D et al. Morton’s metatar- salgia: sonographic findings and correlated histopa- 46. Kilmartin TE, Wallace WA. Effect of pronation and thology. Foot and Ankle International 1999; 20: supination orthosis on Morton’s neuroma and lower 153–161. extremity function. Foot and Ankle International 1994; 15: 256–262. 31. Irwin LR, Konstantoulakis C, Hyder NU et al. Ultra- sound in the diagnosis of Morton’s neuroma. The 47. Miller SJ. Entrapment neuropathies. In: Hethering- Foot 2000; 10: 186–189. ton VJ, eds. Hallux valgus and forefoot surgery. New York: Churchill Livingstone; 1994: 401–428. 32. Quinn TJ, Jacobsen JA, Craig JG et al. Sonography of Morton’s neuromas. American Journal of Roent- 48. Gauthier G. Thomas Morton’s disease: a nerve entrap- genology 2000; 174: 1723–1728. ment syndrome. A new surgical technique. Clinical Orthopaedics and Related Research 1979; 142: 33. Zanetti M, Ledermann T, Zollinger H et al. Efficiency 90–92. of MR imaging in patients suspected of having Mor- ton’s neuroma. American Journal of Roentgenology 49. Mann RA, Reynolds JC. Interdigital neuroma – a 1997; 168: 529–532. critical clinical analysis. Foot and Ankle 1983; 3: 238–243. 34. Hirschberg GG. A simple cure for Morton’s neuralgia. Journal of the American Podiatric Medical Association 50. Gudas CJ, Mattana GM. Retrospective analysis of 2000; 90: 100–101. intermetatarsal neuroma excision with preservation of the transverse metatarsal ligament. Journal of 35. Greenfield J, Rea J, Ilfeld FW. Morton’s interdigital the American Podiatric Medical Association 1986; 25: neuroma: indications for treatment by local injections 459–463. versus surgery. Clinical Orthopaedics and Related Research 1984; 185: 142–144. 51. Nashi M, Venkatachalam A, Muddu B. Surgery of Morton’s neuroma: dorsal or plantar approach? 36. Rasmussen MR, Kitaoka HB, Patzer GL. Nonopera- Journal of the Royal College of Surgeons 1997; 42: tive treatment of plantar interdigital neuroma with a 36–37. single corticosteroid injection. Clinical Orthopaedics and Related Research 1996; 326: 188–193. 52. Colgrove R, Huang E, Barth A et al. Interdigital neuroma: intermuscular neuroma transposition com- 37. Dockery GL. The treatment of intermetatarsal neuro- pared with resection. Foot and Ankle International mas with 4% alcohol sclerosing injections. Journal of 2000; 21: 206–211. Foot and Ankle Surgery 1999; 38: 403–408. 53. Fortin PT, Myerson MS. Second metatarsophalangeal 38. Fanucci E, Masala S, Fabiano S et al. Treatment of joint instability. Foot and Ankle International 1995; intermetatarsal Morton’s neuroma with alcohol injec- 16: 306–314. tion under US guide: 10-month follow-up. European Radiology 2004; 14: 514–518. 54. Mann RA, Mizel MS. Monoarticular synovitis of the metatarsophalangeal joint: a new diagnosis? Foot and 39. Hyer CF, Mehl LR, Block AJ et al. Treatment of Ankle 1985; 6: 18–21. recalcitrant intermetatarsal neuroma with 4% scleros- ing alcohol injection: a pilot study. Journal of Foot 55. Coughlin MJ. Subluxation and dislocation of the and Ankle Surgery 2005; 44: 287–291. second metatarsophalangeal joint. Orthopedic Clinics of North America 1989; 20: 535–551. 40. Bennett GL, Graham CE, Mauldlin DM. Morton’s interdigital neuroma: a comprehensive treatment 56. Dilnot MC, Michaud TC. Plantar plate rupture. Aus- protocol. Foot and Ankle International 1995; 16: tralasian Journal of Podiatric Medicine 2003; 37: 760–763. 43–46. 41. Polokoff MM. The treatment of Morton’s metatarsal- 57. Yu GV, Judge MS, Hudson JR et al. Predislocation gia. Journal of the American Podiatry Association syndrome. Progressive subluxation/dislocation of 1948; 38: 27. the lesser metatarsophalangeal joint. Journal of the American Podiatric Medical Association 2002; 92: 42. Poon C, Love B. Efficacy of foot orthotics for meta- 182–199. tarsalgia. The Foot 1997; 7: 202–204. 58. DuVries HL. Dislocation of the toe. Journal of the 43. McLauchlan PT, Abboud RJ, Rendall GC et al. Use American Medical Association 1965; 160: 728. of an in-shoe pressure system to investigate the effect of two clinical treatment methods for metatarsalgia. 59. Thompson FM, Hamilton WG. Problems of the The Foot 1994; 4: 204–208. second metatarsophalangeal joint. Orthopedics 1987; 10: 83–89. 44. Basadonna P, Rucco V, Gasparini D et al. Plantar fat pad atrophy after corticosteroid injection for interdigi- 60. Coughlin MJ. Second metatarsophalangeal joint insta- tal neuroma: a case report. American Journal of Physi- bility in the athlete. Foot and Ankle International cal Medicine and Rehabilitation 1999; 78: 283–285. 1993; 14: 309–319.

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Disorders of the CHAPTER midfoot and rearfoot 10 CHAPTER CONTENTS PLANTAR HEEL PAIN SYNDROME Plantar heel pain syndrome 191 191 Plantar heel pain is one of the most common condi- Classification and clinical presentation tions affecting the foot, accounting for over 1 000 000 Aetiology 192 patient visits to medical practitioners in the USA per Assessment and diagnosis 193 year. Of these visits, 16% are made by people over the Treatment 194 age of 65 years.1 The Feet First study of 784 Ameri- cans aged over 65 years reported that 4% exhibited Tibialis posterior dysfunction 197 197 tenderness to palpation of the plantar heel pad and Classification and clinical presentation 7% to palpation of the arch, with equal sex distribu- Aetiology 198 tion.2 More recently, Menz et al3 reported that 16% Assessment and diagnosis 198 of 301 people aged over 75 years had disabling foot Treatment 199 pain affecting the heel. Plantar heel pain has also been shown to have a significant impact on mobility and Retrocalcaneal conditions 199 health-related quality of life. Riddle et al4 adminis- Haglund’s deformity 200 tered the Lower Extremity Functional Scale to 50 Achilles tendinopathy 202 participants with heel pain and reported that most experienced some difficulty in walking-related and Osteoarthritis of the midfoot and occupational activities. In older people, the impact of rearfoot 205 the plantar heel pain is considerable. In a secondary Prevalence and risk factors 205 analysis of the Feet First study, Badlissi et al5 found Clinical presentation 206 that older people with heel pain exhibited significantly Conservative treatment 206 lower scores on the Foot Health Status Questionnaire Surgical treatment 207 after accounting for age and comorbidities. Less common midfoot and rearfoot CLASSIFICATION AND CLINICAL disorders 207 PRESENTATION Painful pes cavus 207 Tarsal tunnel syndrome 208 The nomenclature and classification of heel pain is Sinus tarsi syndrome 208 highly problematic. Heel pain has been variably referred to as plantar fasciitis, subcalcaneal bursitis, Summary 208 neuritis, subcalcaneal pain, stone bruise, calcaneal References 209 periostitis, heel spur syndrome, subcalcaneal spur and calcaneodynia.6–8 The most widely used term is plantar

192 DISORDERS OF THE MIDFOOT AND REARFOOT fasciitis; however, recent evidence suggests that to as ‘first step pain’) and tend to subside after this may be a misnomer as no inflammatory cells are walking for a few steps. This is thought to be due to evident in postoperative histology specimens of periods of inactivity causing the accumulation the plantar fascia.9 Similarly, terms incorporating the of oedema within the plantar tissues, which is dis- word ‘spur’ are problematic as calcaneal spurs are persed by the action of the calf muscles when walking. commonly found in people without heel pain.10–12 Most commonly, symptoms are unilateral.15,16 Because the aetiology of heel pain is unclear (and is Symptoms may vary depending on the tissue involved. likely to be multifactorial) the term plantar heel pain In cases with nerve involvement, there may be evi- syndrome is probably the most appropriate terminol- dence of neuritic symptoms (e.g.: burning, radiating ogy to use until a definitive diagnosis is obtained pain),17 while cases with osseous involvement (such as using diagnostic imaging. insufficiency fracture of the calcaneus) do not gen- erally subside after activity.15 Nocturnal pain may Several authors have proposed classification systems indicate less common causes such as tumours or for heel pain, although none have been widely infections.15 adopted. Shikoff et al13 proposed two categories of heel pain: local (including plantar fasciitis and plantar AETIOLOGY calcaneal bursitis) and systemic (including heel pain associated with connective tissue diseases and vascular Pathogenesis disease). Kwong et al14 recommended a more complex classification system, including inflammatory, meta- The pathogenesis of plantar heel pain syndrome is bolic, degenerative, nerve entrapment, traumatic and poorly understood. Traditionally, heel pain was con- overuse subgroups. Perhaps the most useful clinical sidered to be an inflammatory condition of the plantar classification is that proposed by Singh et al,15 which fascia (hence the term plantar fasciitis) caused by categorises inferior heel pain according to the tissue excessive traction and subsequent microtears of the involved (Fig. 10.1). Although in practice there is insertion of the plantar fascia into the calcaneus. His- likely to be some overlap between these categories, tological analysis of postsurgical specimens of the such a system provides a good starting point for dif- plantar fascia, however, indicate several degenerative ferential diagnosis. changes (including fascial thickening, fibrosis, calcifi- cation and collagen necrosis) but no evidence of The classical presentation of plantar heel pain syn- inflammatory cells.9,18–20 The presence of bony spurs drome is that of a sharp pain under the medial heel within the plantar fascia or intrinsic musculature does that may radiate towards the arch. Symptoms are appear to be more common in those with heel pain particularly severe upon rising in the morning (referred compared to controls11,12,21 and diagnostic imaging techniques have revealed several other structural Plantar fascia Soft tissue changes in patients with heel pain, such as fat pad – Fat pad atrophy abnormalities, hyperaemia, adventitious bursae, calca- – Plantar fasciitis – Heel bruise neal stress fractures, bone oedema and partial ruptures – Rupture – Bursitis of the plantar fascia.12,22–24 Taken together, these find- – Enthesopathy ings suggest that heel pain results from a complex degenerative process involving multiple tissues rather Heel pain syndrome than a purely inflammatory response of the plantar fascia. It is likely, however, that the pathological pro- cesses differ depending on whether the condition is acute or chronic. Bone Nerve Risk factors – Calcaneal stress fracture – Tarsal tunnel syndrome Several risk factors for plantar heel pain have been – Paget’s disease – Abductor digiti minimi proposed, which can be summarised as intrinsic – Tumours (including increased body mass index, limited ankle – Infection nerve entrapment range of motion, limb length discrepancy, reduced – Sciatica (S1) radiculopathy Figure 10.1 Classification of heel pain syndrome.

Plantar heel pain syndrome 193 Table 10.1 Factors associated with plantar ASSESSMENT AND DIAGNOSIS heel pain The accurate assessment and diagnosis of heel pain Factor Level of evidence can be difficult, as no widely accepted diagnostic algo- rithm has been developed and at least 30 differential Increased body mass index Strong diagnoses have been reported in the literature.8 A Increased weight provisional diagnosis can be reached from evaluating Older age Weak the location and characteristics of the pain and, in Decreased ankle dorsiflexion ROM Inconclusive practice, most patients are considered to have plantar Decreased first fasciitis (and are treated accordingly) unless proved otherwise. Table 10.2 (modified from Buchbinder16) metatarsophalangeal summarises clinical signs that point towards less joint extension ROM common causes of heel pain. Prolonged standing Pronated foot posture Diagnostic imaging is not always necessary to Reduced calf strength confirm the diagnosis of plantar fasciitis but may play ROM: range of motion a role in excluding other potential diagnoses. Plain film X-rays will assist in ruling out calcaneal stress heel pad thickness, excessive foot pronation and fractures and bony tumours;28 however, the observa- limited first metatarsophalangeal joint range of tion of a calcaneal spur cannot be considered diagnos- motion) and extrinsic (including long periods of tic, as approximately 15–40% of the general population weightbearing activity and inappropriate footwear). A have spurs,11,12 the prevalence of which is associated recent systematic review of factors associated with with increased age, obesity and osteoarthritis.29,30 In heel pain7 summarised the results of 13 case-control a recent study of 27 symptomatic patients and 79 and three case-series studies; a summary of the find- controls, Osborne et al12 found that the combination ings is shown in Table 10.1. Of the multitude of of two observations from a lateral X-ray (plantar fascia proposed risk factors, the factor with the highest level thickness greater than 4 mm and presence of fat pad of evidence was increased body mass index/obesity, abnormalities) provided better differentiation between followed by increased age, decreased ankle dorsiflex- cases and controls than the presence of spurs. ion range of motion, decreased first metatarsophalan- geal joint range of motion and prolonged standing. Bone scanning of painful heels reveals increased Each of these risk factors is consistent with the view blood flow and blood pooling at the insertion of that heel pain results from both the traction placed the plantar fascia in a large number of cases31 and is on the plantar fascia and compressive forces applied thought to be indicative of osteoblastic activity associ- to the heel itself. ated with a periosteal reaction at the enthesis. Groshar et al32 compared 58 symptomatic and 28 asymptom- It should be noted, however, that many of these atic feet and found that a positive bone scan had a studies focused on plantar fasciitis rather than the sensitivity of 78% and specificity of 86% for the detec- broader concept of heel pain syndrome. Furthermore, tion of clinically determined plantar fasciitis. However, few studies have specifically examined risk factors for increased uptake in the plantar heel region may also heel pain in older people. Because of age-related dif- occur in the presence of stress fractures, osteomyelitis ferences in foot structure, particularly the increased and tumours, so it is often difficult to delineate stiffness of the plantar heel pad,25–27 it is likely that the the contribution of specific structures from a positive relative importance of underlying risk factors for heel bone scan. pain in older people may be somewhat different from the situation in younger people. In particular, it is Ultrasound imaging is not routinely used to diag- likely that degenerative changes in the heel resulting nose plantar fasciitis; however, several studies have from vertical compression play a larger role in the shown that people with heel pain demonstrate signifi- development of heel pain in older people. Further- cant increases in the thickness of the plantar fascia more, older people are also more likely to present (approximately 5–7 mm compared to the normal with heel pain associated with an underlying systemic thickness of 2–4 mm).33–37 Furthermore, reduced condition or infection. echogenicity of the plantar fascia is more evident in people with heel pain and may provide greater discrimination than thickness measurements. In the Groshar et al32 study, evidence of hypoechoic regions

194 DISORDERS OF THE MIDFOOT AND REARFOOT Table 10.2 Differential diagnosis of heel pain Diagnosis Distinguishing clinical features Plantar fasciitis Morning pain Plantar fascia rupture Pain on palpation of plantar fascia with toes dorsiflexed Calcaneal stress fracture Sudden onset of pain Inability to bear weight after activity Paget’s disease Bruising and swelling Fat pad atrophy Noticeable decrease in arch height compared to unaffected side Plantar calcaneal bursitis Develops after repetitive weightbearing exercise Medial calcaneal nerve entrapment Tenderness on mediolateral compression of the heel Neuropathic heel pain Plain radiographs may indicate area of sclerosis Bone pain elsewhere in body Bowing of the tibia Pain or tenderness in central heel region Visible atrophy of plantar fibrofatty padding No morning pain Erythema and swelling of the plantar to posterior heel region Burning pain, paraesthesia Positive Tinel’s sign (radiating pain in response to nerve percussion) Diffuse pain Nocturnal pain in the plantar fascia had a positive predictive value of nerve entrapment,17 soft tissue42–46 and osseous47 95% for heel pain compared to 84% for plantar fascial tumours and infections. Nerve entrapments and thickening, and demonstrated similar diagnostic accu- tumours should be suspected in patients with long- racy to bone scanning. standing heel pain that has not responded to conser- vative treatments. Definitive diagnosis will generally Magnetic resonance imaging (MRI) has received require diagnostic imaging and additional diagnostic only limited use in the diagnosis of heel pain; however, tests (e.g. blood tests, synovial fluid analysis). A brief it may assist in the differentiation between plantar summary of these conditions is provided in Table fasciitis and less common conditions. Calcaneal stress 10.3; however, for further detail the reader is referred fractures, plantar fascial tears, plantar fibromatosis to recent comprehensive reviews by Selth & Francis40 and capillary hemangioma of the heel can be clearly and Burns et al.41 detected from MRI scans.22,38,39 MRI may also have a role in presurgical planning. TREATMENT Less common causes of heel pain Conservative A diagnosis of plantar heel pain syndrome accounts A wide variety of conservative treatments have been for the vast majority of plantar heel pain cases; described for heel pain. These can be broadly classi- however, there are several other conditions that may fied into three groups according to the aims of the manifest as pain in the heel region, including systemic treatment: (1) reduction of pain and inflammation, conditions (e.g. rheumatoid arthritis, diffuse idio- (2) reduction of soft tissue stress and (3) restoration pathic skeletal hyperostosis, hypertrophic osteoar- of muscle strength and flexibility (Table 10.4).48 thropathy, psoriatic arthritis and other seronegative Anecdotally, conservative management is believed to spondyloarthropathies, gout and Paget’s disease),40,41

Plantar heel pain syndrome 195 Table 10.3 Less common causes of heel pain Classification Disease/condition Characteristic presentation Systemic conditions Rheumatoid arthritis Bilateral heel pain, may be associated with plantar Diffuse idiopathic skeletal rheumatoid nodules and large calcaneal spurs Nerve entrapment Soft tissue tumours hyperostosis Multiple painful entheses in the spine, shoulder, elbow, Osseous tumours Hypertrophic osteoarthropathy pelvis, knee and foot. Large, irregular calcaneal spurs with no evidence of erosion or periosteal reaction Psoriatic arthritis Seronegative Acute unilateral heel pain with periostitis and increased bone density of the calcaneus, often accompanied by soft spondyloarthropathies tissue swelling of the toes and clubbed nails Gout Paget’s disease Large, irregular calcaneal spurs with fluffy appearance, often May affect medial calcaneal, accompanied by ‘sausage digits’ (fingers and toes) medial plantar or lateral Symmetrical peripheral arthritis, soft tissue swelling, plantar nerves inflammation of calcaneal enthesis Soft tissue chondroma Tophaceous deposits and associated erosive lesions of the Intraosseous lipoma calcaneus Osteoid osteoma Severe, continuous deep bone pain affecting the calcaneus Numbness, pins and needles and/or radiating pain that can be elicited by stroking the medioplantar region of the heel Unilateral, circumscribed, firm, freely moveable subcutaneous mass on the plantar aspect of the heel. Pain aggravated by standing and relieved by rest No obvious physical signs. Unilateral, pain worse in mornings and relieved by rest. Pain can be elicited from lateral compression of the heel Palpable mass, deep-seated pain that is worse in the evenings Table 10.4 Conservative treatments for heel pain Reduction in pain and inflammation Reduction of tissue stress Restoration of muscle strength and flexibility Rest Footwear modification/change Reduction in activity Strapping Calf muscle stretching Ice Padding Night stretch splints Anti-inflammatory medications Heel cups Massage Foot orthoses Therapeutic ultrasound Casting/bracing Low-intensity laser Iontophoresis Herbal medicine Acupuncture Extra-corporeal shockwave therapy

196 DISORDERS OF THE MIDFOOT AND REARFOOT be effective in the majority of cases; however, few Furthermore, night splints are not well tolerated by detailed studies have been undertaken. A review of many patients, as they are cumbersome and may inter- 250 heel pain patients by Weil et al49 claimed an 85% fere with normal sleeping patterns. In one study, success rate with a standardised conservative treat- 19% of the patients reported dissatisfaction with this ment regimen consisting of activity modification, calf treatment approach.58 Active calf muscle stretching, stretching, non-steroidal anti-inflammatory medica- although commonly used as an adjunct treatment in tions (NSAIDs), cortisone injection and customised clinical practice, does not appear to be effective in foot orthoses. A somewhat lower success rate was isolation. Radford et al60 compared 2 weeks of daily reported by Taunton et al,50 with only 40% of 78 calf stretching versus sham ultrasound and found no patients reporting 75% of greater improvement in significant differences in pain reduction between the symptoms following a similar conservative treatment two groups. approach. Finally, a long-term follow-up study of 100 conservatively-managed patients followed for an A variety of foot orthoses are used for the manage- average of 4 years by Wolgin et al51 reported that 82% ment of plantar heel pain, including prefabricated experienced complete resolution of their symptoms. insoles, customised orthoses and various cushioning No studies have specifically addressed success rates devices. Two trials found no benefit of magnetic in older people. However, it is widely believed that insoles over simple cushioning insoles,61,62 while four the longer the duration of symptoms, the more diffi- trials comparing prefabricated orthoses to custom cult heel pain is to manage with conservative orthoses reported quite variable findings. Lynch approaches.51 et al54 compared (1) low-Dye taping followed by custom foot orthoses to (2) an accommodative visco- The most recent Cochrane review of treatments for elastic heel insert and (3) corticosteroid injection fol- heel pain collated the results of 19 randomised lowed by NSAIDs and found that the custom controlled trials (RCTs) involving 1626 patients.52 orthoses/taping group demonstrated greater reduc- Overall, the quality of many of the studies was poor. tions in pain after 3 months. Similarly, Turlik et al63 Nevertheless, there was some evidence for the efficacy reported that ‘functional’ orthoses were more effec- of corticosteroid injection, limited evidence for topical tive than cushioned heel pads. In contrast to these corticosteroid administered by iontophoresis, dorsi- findings, Martin et al64 found no differences between flexion night splints and foot orthoses, and no evi- prefabricated orthoses, customised orthoses and dor- dence to support the efficacy of therapeutic ultrasound, siflexion night splints, and Pfeffer et al65 found that laser or magnetic insoles. Brief summaries of the evi- prefabricated orthoses were more effective than cus- dence for these treatments are provided below. tomised orthoses or stretching. Corticosteroid injections have been evaluated in Since the publication of the Cochrane review, two three published randomised controlled trials,53–55 key RCTs have been reported in the literature relating none of which reported significant long-term reduc- to mechanical treatments. Radford et al66 randomised tions in pain compared to a placebo. However, Craw- 92 people with heel pain to receive either low-Dye ford et al55 reported a small but statistically significant taping or sham ultrasound and found that the taping reduction in pain at 1 month follow-up. The efficacy group reported a small but significant reduction in of repeated injections over a prolonged period is first-step pain after 1 week compared to the sham uncertain, although, given that there have been group. Landorf et al67 compared semi-rigid custom- reports of plantar fascial rupture associated with long- ised orthoses to prefabricated orthoses and a sham term corticosteroid use,56,57 it appears that corticoste- insole and found that, while both the customised and roid injection is best reserved for short-term pain prefabricated orthoses improved function to a similar relief. degree at 3 months, no significant differences between the three groups for pain or function were noted at Dorsiflexion night splints are worn while sleeping 12 months, suggesting that plantar heel pain may be and align the ankle in a neutral or dorsiflexed position self-limiting. This paper also included a meta-analysis while the metatarsophalangeal joints are also dorsi- of their results combined with three similar trials flexed, thereby causing a gradual passive stretch of the (Lynch et al,54 Pfeffer et al65 and Martin et al64), which calf muscles and the plantar fascia. The efficacy of this indicated no significant benefit of custom orthoses treatment approach is uncertain, as, although one over prefabricated orthoses. Taken together, these crossover trial reported significant reductions in findings suggest that the treatment regimen com- pain,58 another trial failed to show such a benefit.59

Tibialis posterior dysfunction 197 monly employed by podiatrists (taping followed by pression.80 Although case series studies indicate orthoses) is effective in the short term; however, there very high levels of patient satisfaction (ranging from appears to be no benefit of custom orthoses over 81% to 94%),20,81,82 no randomised trials have been prefabricated orthoses. undertaken. Recovery from surgery may take several months and complications including scarring, medial The efficacy of shock-absorbing heel pads and rigid arch pain, cramping and calcaneal fracture have been heel cups has not been rigorously evaluated; however, reported in up to 10% of patients.82 Surgical interven- it is likely that rigid heel cups may be of particular tion for heel pain should be very carefully considered value in managing heel pain in older people. As stated in older people because of prolonged recovery times previously, it has been shown that ageing is associated and the increased risk of acquired flat foot with significant increases in the stiffness of the plantar deformity. heel pad25–27 due to breakdown of the fibrous septa and a subsequent increase in lateral expansion when TIBIALIS POSTERIOR DYSFUNCTION weightbearing. By confining the lateral expansion of CLASSIFICATION AND the heel pad with rigid heel cups, the vertical thickness CLINICAL PRESENTATION of the pad is maintained, which may enhance shock absorption and prevent further damage to soft tissue Tibialis posterior dysfunction (TPD) is a condition in structures in the plantar heel region.68,69 Uncontrolled which the tendon of the tibialis posterior muscle studies have reported good clinical results with the becomes weak and elongated, leading to a progres- use of rigid heel cups in patients with ‘bruised heels’70 sive, painful flat foot deformity (Fig. 10.2).83 Although and it is possible that circumferential taping around the prevalence is unknown, the condition most com- the heel has a similar effect. monly affects middle-aged and elderly women. The classical features of TPD are a progressive flattening The effectiveness of extracorporeal shockwave of the foot, tenderness and swelling along the tibialis therapy is uncertain. This relatively new treatment involves the transcutaneous application of shockwaves A into the heel region with the aim of stimulating healing of the enthesis and inhibiting pain receptors. B Of the eight RCTs that have been conducted, three Figure 10.2A, B Pes planus (flat foot). (A, courtesy of showed no benefit71–73 and five reported small reduc- Lloyd Reed, Queensland University of Technology.) tions in pain when compared to a placebo.74–78 These findings, however, need to be viewed with some caution. Firstly, the generalisability of these findings is limited, as inclusion into four of these studies required the positive identification of a calcaneal spur from X-ray. Secondly, many of these trials were of low quality, with a tendency towards lower-quality trials and trials funded by shock-wave device manufacturers reporting more favourable outcomes.79 It is also worth noting that extracorporeal shockwave therapy without local anaesthesia is generally considered to be painful. In one study, 79% of people reported pain during treatment.77 Surgical Surgery for heel pain is generally only considered appropriate for a select group of patients who have had severe, chronic pain and have failed to respond to several conservative treatments.15,16 Numerous techniques have been described, involving total or partial release of the plantar fascia with or without resection of the calcaneal spur and tibial nerve decom-

198 DISORDERS OF THE MIDFOOT AND REARFOOT Table 10.5 Classification of tibialis posterior Figure 10.3 Typical plantar pressure output of a patient dysfunction with tibialis posterior dysfunction. Stage Features 1 Tendon inflamed No change in foot shape 2 Tendon elongated Acquired flat foot deformity 3 Fixed deformity Degenerative changes at subtalar joint 4 Fixed deformity Degenerative changes at subtalar and ankle joints posterior tendon as it passes behind the medial mal- female sex, obesity and hypertension.95 TPD may also leolus, and reported difficulty in walking on uneven be a cause of flat foot deformity in people with rheu- surfaces.84–86 However, there is a broad spectrum of matoid arthritis.96 TPD severity, which has led to the development of several classification systems. Johnson & Strom87 pro- As TPD progresses, the arch becomes progressively posed three stages, Myerson88 added a fourth stage lower, the calcaneus everts and the forefoot abducts incorporating arthritic changes in the ankle joint, relative to the rearfoot. This change in foot posture Mueller89 proposed a different four stage classification results in significant alterations to the weightbearing system incorporating an asymptomatic stage, and function of the foot, characterised by increases in Wainwright et al90 have proposed a classification rearfoot eversion, increased medial plantar pressure system based on MRI findings. The modified scale distribution (Fig. 10.3), and increased electromyo- reported by Myerson88 is provided in Table 10.5. graphic activity of the tibialis posterior muscle.97,98 Over time, the altered function of the foot often AETIOLOGY results in arthritic degeneration of the joints of the midfoot and rearfoot.99 The pathogenesis of TPD is poorly understood. His- tological studies of affected tendons demonstrate fea- ASSESSMENT AND DIAGNOSIS tures of chronic tendon degeneration accompanied by fibrosis but no evidence of inflammatory cells.91,92 The assessment of TPD is relatively straightforward, These changes are thought to result from repeated as a diagnosis can be reached on the basis of history microtrauma caused by excessive strain placed on the taking and physical examination. In the early stages, tendon in the presence of mild flat foot. Vascular patients will report a vague, insidious pain around the factors may also play a role, as a hypovascular region medial malleolar region. As the condition progresses, in the tendon has been identified posterior and infe- patients may also report noticing changes in the shape rior to the medial malleolus, where the tendon is of the affected foot and difficulty performing certain firmly tethered by the flexor retinaculum.93 Ligamen- activities, such as walking up stairs or over uneven tous damage is frequently observed in advanced cases, ground.84,86,100,101 In advanced cases, the foot becomes with the spring ligament complex being particularly markedly everted and pain may develop in the lateral affected.94 However, whether the tendon dysfunction ankle region as the calcaneus abuts against the distal precedes ligament damage or vice versa remains fibula.84 A recent study of 65 older people indicated unclear. No case-control studies have been conducted that positive responses to two statements on a ques- to ascertain the risk factors associated with TPD; tionnaire – regarding the presence of pain and swell- however, case series studies indicate that the condi- ing in the medial ankle region and observations of tion appears to be associated with advancing age, changes in the shape of the foot – detected 100% of patients who had been clinically diagnosed with TPD, with a specificity of 98%.85