Netter Concise Orthopaedic Anatomy 2nd Edition

9 Leg/Knee • RADIOLOGY AP radiograph of knee Lateral radiograph of knee Patella Medial femoral Lateral condyle femoral condyle Tibial Trochlear Lateral spines groove tibial Lateral plateau tibial Medial Patella (convex) plateau tibial plateau Sulcus Medial Fibular terminalis tibial head plateau (concave) Tibial tubercle Blumensaat’s line Notch radiograph Sunrise radiograph Tibial spines Lateral Intercondylar Lateral femoral condyle notch patellar Lateral facet tibial plateau Medial Lateral Medial femoral femoral patellar condyle condyle facet Medial Trochlear groove Medial femoral tibial condyle plateau RADIOGRAPH TECHNIQUE FINDINGS CLINICAL APPLICATION KNEE AP Supine; beam at 90° Medial/lateral compartments; Femoral condyle, tibial plateau/ varus/valgus deformity spine, patella fx, OCD, osteo- Lateral Supine; 30° flexion arthritis (weight-bearing) Patellofemoral compartment Axial/ Prone; knee 115° flex; beam Fractures, quadriceps/patellar sunrise at patella 15° cephalad Patellofemoral compartment tendon rupture (patellar articular facets) Tunnel/ Prone; knee 45° flex; beam Posterior femoral condyles, inter- Patellofemoral arthritis, mal- notch is caudal at knee joint condylar notch, tibial eminence alignment or patellar tilt Merchant Supine; legs of table at 45°; Patellofemoral compartment Osteochondral fx/defect, femo- Rosenberg beam at PF joint (patellar articular facets) ral condyle or tibial eminence Medial/lateral compartments fx, DJD/osteoarthritis PA (weight-bearing); knees at 45° Articular surface lesions, DJD, tilt or malalignment Osteoarthritis of WB portion of posterior condyles 290 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

AP radiograph RADIOLOGY • Leg/Knee 9 Lateral radiograph Alignment radiograph Tibial Diaphysis Center plateau of hip Metaphysis Tibial plafond Fibula Medial Center Lateral malleolus of knee malleolus Fibula Center Tibial of ankle (a plateau Tibial line drawn Tibial plafond from the hip tubercle to the ankle should pass Diaphysis the center of the knee in neutral alignment) RADIOGRAPH TECHNIQUE FINDINGS CLINICAL APPLICATION LEG Fractures, deformity, infection, etc Fractures, deformity, infection, etc AP tibia Supine; beam at mid Tibia and surrounding soft tissues tibia Determine malalignment/deformity Used for leg length discrepancy Lateral tibia Supine; beam later- Tibia and surrounding soft tissues Intraarticular condyle, plateau, ally mid-tibia pilon fxs Ligament ruptures, meniscal tears, See Foot & Ankle chapter to see views of the ankle. OCD, stress fxs, tumor, infection Stress fxs, infection, tumor OTHER STUDIES Alignment films Bilateral full length Full lower extremity alignment hip to ankle, WB Scanogram Entire bilateral LE Measure length of bones with ruler CT Axial, coronal, & Articular congruity, fracture sagittal views fragments MRI Sequence protocols Soft tissues: ligaments, meniscus, vary articular cartilage, bone marrow Bone scan Radioisotope All bones evaluated NETTER’S CONCISE ORTHOPAEDIC ANATOMY 291

9 Leg/Knee • TRAUMA Fracture of Patella Nondisplaced trans- Displaced transverse Transverse fracture Severely comminuted verse fracture with fracture with tears with comminution of fracture intact retinacula in retinacula distal pole Dislocation of Knee Joint Types of dislocation Anterior Posterior Lateral Medial Rotational DESCRIPTION EVALUATION CLASSIFICATION TREATMENT PATELLAR FRACTURE • Mechanism: direct & indi- Hx: Trauma, pain, cannot Descriptive/location: • Nondisplaced or rect: e.g., fall, dashboard, extend knee, swelling comminuted—knee etc. PE: “Dome” effusion, ten- ‫ ؠ‬Nondisplaced brace/cast 6-8 wk, ROM derness, ϩ/Ϫ palpable ‫ ؠ‬Transverse • Pull of quadriceps and ten- defect, inability to extend ‫ ؠ‬Vertical • Displaced (Ͼ2-3mm): dons displace most fxs knee ‫ ؠ‬Stellate ORIF (e.g., tension XR: Knee trauma series ‫ ؠ‬Inferior/superior pole bands) to restore articu- • If intact, retinaculum resists CT: Not usually needed, will ‫ ؠ‬Comminuted lar surface displacement of fragments show fx fragments • Severely comminuted: • Do not confuse with bipar- may require full or par- tite patella (unfused supero- tial patellectomy lateral corner) COMPLICATIONS: Osteoarthritis and/or pain, decreased motion and/or strength, osteonecrosis, refracture KNEE DISLOCATION • Rare: ortho. emergency Hx: Trauma, pain, inability By position: • Early reduction essen- • Usually high-energy injury to bear weight ‫ ؠ‬Anterior tial; postreduction neu- • Multiple ligaments & other PE: Large effusion, soft tis- ‫ ؠ‬Posterior rologic exam and x-rays sue swelling, deformity, ‫ ؠ‬Lateral soft tissue are disrupted pain, ϩ/Ϫ distal pulses/ ‫ ؠ‬Medial • Immobilize (cast) 6-8wk • High incidence of associ- peroneal nerve function ‫ ؠ‬Rotatory: anterome- (if ligaments not torn) XR: AP/lateral ated fx & neurovascular AGRAM: Evaluate for arte- dial or anterolateral • Surgery if irreducible or injury rial injury vascular injury (revascu- • Many spontaneously MR: Ligament injury, me- larize within 6 hr ϩ reduce; must keep index of niscus, articular cartilage fasciotomy). suspicion for injury injury • Close follow-up is important • Early vs. delayed for good result ligament repair/ reconstruction COMPLICATIONS: Neurovascular: popliteal artery, peroneal nerve injury, knee stiffness (#1), chronic instability 292 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

TRAUMA • Leg/Knee 9 Tibial Plateau Fracture I. Split fracture of lateral tibial plateau II. Split fracture of lateral condyle III. Depression of lateral tibial plus depression of tibial plateau plateau without split fracture IV. Comminuted split fracture of medial V. Biocondylar fracture involving VI. Fracture of lateral tibial plateau tibial plateau and tibial spine both tibial plateaus with widening with separation of metaphyseal- diaphyseal junction DESCRIPTION EVALUATION CLASSIFICATION TREATMENT TIBIAL PLATEAU FRACTURE • Mechanism: axial load AND Hx: Trauma, pain, swell- Schatzker (6 types): • Consider joint aspiration varus/valgus stress ing, inability to bear I: Lateral plateau split fx • Nondisplaced (Ͻ3mm weight II: Lat. split/depression fx • Restoration of articular PE: Effusion, tenderness; III: Lat. plateau depression step off,Ͻ5mm gap- surface/congruity is important do thorough neurovas- IV: Medial plat. split fx ping): knee brace/cast cular exam. V: Bicondylar plateau fx 6-8wk, NWB 6-12wk • Metaphyseal injury: bone will XR: Knee trauma series VI: Fx w/metaphyseal- • Displaced: ORIF ϩ/Ϫ compress, leading to func- CT: To better define fx bone graft (plates & tional bone loss; may need lines & comminution. diaphyseal separation screws). Early ROM but bone graft Needed for preop plan- Types IV-VI usually result NWB 12wk ning. from high-energy • Avoid both medial & • Lateral fracture more com- AGRAM: If decreased trauma lateral periosteal strip- mon than medial pulses. Consider in all ping (incr. nonunion type IV fxs rate) • Associated meniscal (50%) • Repair torn ligaments/ and ligament (MCLϾACL) menisci tears COMPLICATIONS: compartment syndrome, posttraumatic osteoarthritis, persistent knee pain, popliteal artery injury NETTER’S CONCISE ORTHOPAEDIC ANATOMY 293

9 Leg/Knee • TRAUMA Fracture of Shaft of Tibia Transverse Spiral Comminuted Segmental fracture; fracture fracture with fracture fibula with marked with intact shortening shortening marked shortening Incisions for Compartment Syndome of Leg Interosseous membrane Anterior compartment Extensor muscles Deep posterior compartment Tibia tibialis anterior extensor digitorum longus Deep flexor muscles extensor hallucis longus flexor digitorum longus Anterior tibial a. and v. tibialis anterior Deep peroneal n. flexor hallucis longus Anterolateral incision Posterior tibial a. and n. Tibial n. Anterior intermuscular septum Peroneal a. and n. Posteromedial incision Fibula Lateral compartment Peroneal muscles Transverse intermuscular septum Crural (encircling) fascia peroneus longus peroneus brevis Superficial posterior compartment Superficial peroneal n. Superficial flexor muscles soleus Posterior intermuscular septum gastrocnemius plantaris tendon DESCRIPTION EVALUATION CLASSIFICATION TREATMENT TIBIA SHAFT FRACTURE • Common long bone fx Hx: Trauma, pain, swelling, Descriptive: • Nondisplaced: long leg • Usually high-E trauma inability to bear weight Location cast 8wk (best for pedi- • Condition of surrounding PE: Swelling, deformity, Displaced/comminuted atrics, seldom used in ϩ/Ϫ firm/tense compart- Type: transverse, spiral adults) soft tissues is critically ments oblique important to success of XR: AP & lateral of tib./fib. Rotation/angulation • Displaced/unstable: outcome (also knee & ankle series) reamed, locked IM nail • Compartment syndrome: CT: Not usually needed consider in ALL fxs AGRAM: If decreased • Open fractures: thorough • Subcutaneous position of pulses I&D is critical. External tibia predisposes it to fixation is useful for open fractures these fractures. • May lead to amputation • Fasciotomies for com- partment syndrome COMPLICATIONS: compartment syndrome, nonunion & malunion, knee pain (from IM nail), ankle and/or knee stiffness COMPARTMENT SYNDROME • Incr. pressure in closed Hx: Trauma, pain XR: Evaluate for fractures • Usually a clinical diagnosis space/compartment PE: 5 P’s: pain (w/passive Angiogram: If needed to • Emergent fasciotomy stretch), paresthesia, pal- evaluate for vascular inj. • Compartments (4): have lor, pulseless, paralysis Compartment Pressures: (usually two incisions) rigid fibroosseous borders Firm/tense compartments 1. Absolute: Ͼ30-40mmHg 2. ⌬P: Ͻ30mmHg of • Mechanism: trauma (fracture, crush) vascular diastolic blood pressure injury, burn 294 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

TRAUMA • Leg/Knee 9 Torn deltoid ligament Pilon fracture Usual cause is vertical loading of ankle joint, eg, falling from height and landing on heel (usually with ankle dorsiflexed). Fracture and compression of articular surface of tibia plus separation of malleoli and fracture of fibula Maisonneuve fracture Complete disruption of tibiofibular syndesmosis with diastasis caused by external rotation of talus and trans- mission of force to proximal fibula, resulting in high fracture of fibula. Interosseous membrane torn longitudinally. Radiograph shows repair with long transverse screw (these fractures easily missed on radiographs) DESCRIPTION EVALUATION CLASSIFICATION TREATMENT MAISONNEUVE FRACTURE • Complete syndesmosis Hx: Trauma, ankle pain,ϩ/Ϫ knee Descriptive: Reduce and stabilize disruption with diastasis pain Location syndesmosis (e.g., & proximal fibula fx PE: Ankle pain, swelling, proxi- Type: Spiral with a screw); immobi- mal fibula tenderness lize while healing • Variant of ankle fracture XR: Leg and ankle series. May Oblique & deltoid ligament need stress views of ankle to Comminuted rupture see instability • Unstable fracture COMPLICATIONS: ankle instability, ankle arthritis PILON (DISTAL TIBIA) FRACTURE • Intraarticular: through Hx: Trauma, cannot bear weight, Ruedi/Allgower • Nondisplaced: cast & distal articular/WB pain, swelling (3 types): NWB for 6-12wk surface PE: Effusion, tenderness; do I: Non or minimally good neurovascular exam displaced • Displaced/comminuted: • Soft tissue swelling leads XR: AP/lateral (obliques) II: Displaced: articular early external fixation to complications with CT: Needed to better define fx surface incongruous and delayed (14 days) early open treatment and preop plan III: Comminuted articular ORIF; (plates & screws surface ϩ/Ϫ bone grafting) • Restoration of articular surface congruity is es- sential • Healing is often slow COMPLICATIONS: posttraumatic DJD, (almost 100% in comminuted fxs), stiffness, malunion, wound complications NETTER’S CONCISE ORTHOPAEDIC ANATOMY 295

9 Leg/Knee • JOINTS Anterior view Femur of knee Trochlea Patella Lateral Lateral Medial condyle epicondyle epicondyle Lateral Medial Lateral Medial plateau condyle condyle condyle of femur of femur Gerdy Medial tubercle plateau Lateral Medial condyle condyle of tibia of tibia Line of attachment of synovium Head of Tibia (edge of articular cartilage) to fibula distal femur Line of reflection of synovial Fibula Intercondylar membrane eminence KNEE Structure • Comprises 3 separate articulations ‫ ؠ‬Medial & lateral femorotibial joints (2)—condyloid (hinge) joints. Femoral condyles articulate with corresponding tibial plateaus. ‫ ؠ‬Patellofemoral joint (1)—sellar (gliding) joint. Patella articulates with femoral trochlear groove. • 3 compartments in the knee: medial, lateral, patellofemoral • Capsule surrounds entire joint (all three articulations/compartments) and extends proximally into the suprapatellar pouch. ‫ ؠ‬The capsule has a synovial lining that also covers the cruciate ligaments (making them intraarticular but extrasynovial) • Articular (hyaline) cartilage (type II collagen) covers the femoral condyles, tibial plateaus, trochlear groove, and patellar facets. • Menisci are interposed in the medial & lateral femorotibial joints to: 1.protect the articular cartilage, 2. give support to the knee. • Knee axis (line drawn between weight-bearing portion of medial & lateral femoral condyles) is parallel to the ground. ‫ ؠ‬Mechanical axis of the femur is 3° valgus to the vertical axis, allowing the larger MFC to align with the LFC parallel to the ground. ‫ ؠ‬Mechanical axis of the tibia is 3° varus to the vertical axis (87° to knee axis). Kinematics • Inherently unstable joint. Bony morphology adds little stability. Stability primarily provided by surrounding static and dynamic stabi- lizers. (Dynamic stabilizers may compensate when static stabilizers are injured [e.g., complete or partial ACL rupture].) ‫ ؠ‬Medial: Static—superficial and deep medial collateral ligaments (MCL), posterior oblique ligament (POL). Dynamic—semimembranosus, vastus medialis, medial gastrocnemius, PES tendons ‫ ؠ‬Lateral: Static—lateral collateral ligament (LCL), iliotibial band (ITB), arcuate ligament. Dynamic—popliteus, biceps femoris, lateral gastrocnemius • Not a simple hinge joint. The knee has 6 degrees of motion: ‫ ؠ‬Extension/flexion, IR/ER, varus/valgus, anterior/posterior translation, medial/lateral translation, compression/distraction • Flexion & extension are the primary motions in the knee. ‫ ؠ‬Flexion is a combination of both “rolling” and “sliding” of the femur on the tibia in varying ratios depending on the degree of flexion. ‫ ؠ‬Rolling: equal translation of tibiofemoral contact point & joint axis. Rolling predominates in early flexion. ‫ ؠ‬Gliding: translation of tibiofemoral contact point without moving the joint axis. Increased gliding is needed for deep flexion. ‫ ؠ‬The cruciate ligaments control the roll/glide function. The PCL alone can maintain this function (e.g., PCL retaining TKA). ‫ ؠ‬Normal motion: Extension/flexion: Ϫ5 to 140°. 115° needed to get out of a chair; 130° needed for fast running. • IR/ER: about 10° total through arc of motion. Tibia IRs in swing, and ERs in stance via “screw home mechanism.” ‫ ؠ‬Screw home mechanism: larger MFC ERs tibia in full extension, tightening cruciates and stabilizing the knee in stance. ‫ ؠ‬Popliteus IRs the tibia to “unlock” the knee, loosen the cruciates, which allows the knee to initiate flexion. • Other motions: Medial/lateral translation: minimal in normal knees ‫ ؠ‬Anterior/posterior translation: dependent on tissue laxity, usually within 2mm of contralateral side in normal knees ‫ ؠ‬Varus/valgus: approximately 5mm of gapping laterally or medially when stressed in normal knees 296 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Joint opened, Femur Suprapatellar JOINTS • Leg/Knee 9 (synovial) bursa knee slightly Articularis MRI in flexion genus muscle Cruciate ligaments (covered by synovial ACL Synovial membrane membrane) Intercondylar notch (cut edge) Medial condyle Anterior cruciate ligament Lateral condyle of femur of femur visualized between femoral Infrapatellar condyles Origin of popliteus synovial fold tendon (covered by Posterolateral synovial membrane) Medial meniscus Subpopliteal recess Alar folds (cut) Lateral meniscus Infrapatellar fat pads (lined by synovial Fibular collateral membrane) ligament Suprapatellar (synovial) Head of fibula bursa (roof reflected) Patella (articular surface on posterior aspect) Vastus medialis muscle (reflected Vastus lateralis muscle inferiorly) (reflected inferiorly) Right knee in flexion: anterior view Anterior cruciate Posterior ligament cruciate ligament Lateral condyle of Medial condyle femur (articular of femur (articular surface) surface) Popliteus tendon Medial meniscus Fibular collateral Tibial collateral ligament ligament Lateral meniscus Medial condyle of tibia Transverse ligament of knee Head of fibula Tibial tuberosity Gerdy’s tubercle LIGAMENTS ATTACHMENTS FUNCTION/COMMENT KNEE Femorotibial Joint—Anterior Structures Anterior cruciate ligament Posteromedial aspect of lateral Primary restraint to anterior tibial translation; (ACL) femoral condyle to anterior tib- secondary restraint to varus (in extension) & IR Anteromedial bundle ial eminence Tight in knee flexion, lax in extension Posterolateral bundle Tight in knee extension, lax in flexion Transverse meniscal ligament Connects both anterior horns of Stabilizes menisci; can be torn/injured menisci to tibia Other Structures Ligamentum mucosum Distal femoral articulation to Synovial remnant. Covers anterior notch (ACL); (anterior plica) anterior tibial plateau may need to be debrided for full visualization Infrapatellar fat pad Posterior to patellar tendon, an- Cushions patellar tendon. Can become fibrotic terior to intercondylar notch or impinged on, causing knee pain (Hoffa syndrome) See Patellofemoral Joint for other anterior structures NETTER’S CONCISE ORTHOPAEDIC ANATOMY 297

9 Leg/Knee • JOINTS Femur (popliteal surface) MRI Attachment of joint capsule PCL Right knee: posterior view Adductor magnus tendon Plantaris muscle Lateral head of Medial head of gastrocnemius muscle and gastrocnemius subtendinous bursa muscle and subtendinous bursa Lateral (fibular) collateral Medial (tibial) ligament and its inferior collateral ligament subtendinous bursa Semi- Biceps femoris tendon membranosus and bursa beneath it tendon Popliteofibular ligament Semimembranosus Arcuate ligament bursa deep to (lateral arm) tendon (broken line) Oblique popliteal ligament Head of fibula (tendinous expansion of semi- Posterior ligament of membranosus muscle) fibular head Attachment of joint capsule Popliteus muscle Tibia Interosseous membrane Right knee in extension: Posteromedial compartment posterior view Posterior cruciate ligament Adductor tubercle on medial epicondyle of femur Anterior cruciate ligament Medial condyle of Posterior meniscofemoral femur (articular surface) ligament (of Wrisberg) Medial meniscus Lateral condyle of Posterior femur (articular cruciate Tibial collateral ligament surface) ligament seen beyond medial Medial condyle of tibia Popliteus tendon meniscus Fibular collateral ligament Lateral meniscus Broken lines Head of fibula indicate medial collateral ligament LIGAMENTS ATTACHMENTS COMMENTS Posterior cruciate KNEE ligament (PCL) Femorotibial Joint—Posterior Structures Anterolateral bundle Posteromedial bundle Lateral aspect (in notch) of medial Primary restraint to posterior tibial translation Meniscofemoral ligaments femoral condyle to post. proximal Secondary restraint to varus, valgus, and ER tibia (below joint line) Ligament of Humphrey Ant. origin on condyle, lat. on tibia Tight in knee flexion, lax in extension Ligament of Wrisberg Post. origin on condyle, med. on tibia Tight in knee extension, lax in flexion Oblique popliteal ligament (OPL) Posterior lateral meniscus to MFC Variably present. Rarely are both present and/or PCL, either: Anterior to PCL Contributes to PCL function & stabilizes meniscus Posterior to PCL Contributes to PCL function & stabilizes meniscus Origin on semimembranosus inser- Tightens posterior capsule when semimembrano- tion on posterior tibia; inserts on sus contracts; considered part of “posterome- posterior LFC & capsule dial” corner 298 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Leg/Knee 9 Biceps Knee joint: lateral view Vastus lateralis Posterolateral Iliotibial band (cut) femoris muscle oblique view Plantaris muscle muscle Short (cut) head lliotibial Biceps Gastrocnemius muscle Long (lateral head cut) head tract femoris (cut) band Lateral joint capsule Peroneal Lateral retinaculum Bursa deep to nerve (cut) iliotibial tract Lateral patello- Quadriceps Gastrocnemius muscle femoral ligament Lateral (fibular) femoris collateral ligament (medial head cut) Popliteus tendon and bursa deep to it tendon (insertion) Posterior joint Plantaris muscle Lateral Lateral collateral capsule ligament Biceps femoris patellar tendon and its retinaculum Oblique Fabellofibular inferior sub- popliteal ligament tendinous bursa Patella ligament Popliteofibular Common fibular ligament (peroneal) nerve Lateral patellar Semi- tibial ligament membranous Iliotibial band (cut) Gastrocnemius tendon (cut) muscle Joint capsule Lateral arm of knee Medial arm arcuate ligament Head of fibula arcuate Patellar ligament Biceps femoris (cut) ligament Inferior lateral Deep peroneal nerve Tibial geniculate artery tuberosity Popliteus muscle Soleus Fibularis (peroneus) Tibialis anterior Tibia Superficial muscle muscle Peroneal nerve (cut) Fibula peroneal nerve longus muscle LIGAMENTS ATTACHMENTS FUNCTION/COMMENT KNEE Iliotibial band (tract) (ITB) Femorotibial Joint—Lateral and Posterolateral Structures First Layer—Superficial 3 insertions: 1.Gerdy’s tubercle, 2. patella and Stabilizes lateral knee—“accessory anterolateral liga- patellar tendon, 3. supracondylar tubercle ment.” Post. in flexion (ERs tibia), ant. in extension Biceps femoris 2 heads insert on fibular head, lateral to LCL Lateral stabilizer, also externally rotates tibia Lateral patellofemoral ligament Second Layer—Middle Lateral patellar retinaculum Lateral femur to lateral edge of patella May need release if tightened and causing patella tilt SUPERFICIAL LAMINA Vastus fascia to tibia & patella and abnormal lateral articular cartilage wear Third Layer—Deep Lateral collateral lig. (LCL) Lateral epicondyle to medial fibular head Primary restraint to varus stress, also resists ER Fabellofibular ligament Fibula head to fabella, usually with arcuate lig. Variably present, also called “short collateral” DEEP LAMINA Popliteus muscle and tendon Inserts anterior and distal to LCL origin Resists tibia ER, varus, and posterior translation Popliteofibular ligament (PFL) Popliteus musculotendinous jxn to fibula head Primary static restraint to external rotation (ER) Capsule Femur to tibia. Extends 15mm below joint line Reinforced by other structures; resists varus & ER Arcuate ligament Lateral arm: fibular head to posterior femur Variably present, Y-shaped: two arms. Lateral arm Lateral meniscus Medial arm: post-lat femur, blends with OPL covers popliteus supporting posterolateral knee Other Gives concavity to the convex lateral plateau To lateral plateau via coronary ligaments Lateral head of gastrocnemius Origin is on posterior lateral condyle Adds dynamic support to posterolateral knee • The inferior lateral geniculate artery passes between the superficial and deep lamina of the third layer of the posterolateral corner. • The LCL, popliteus, and popliteofibular ligament are the most consistent structures and are the focus of surgical reconstruction. • Most of the posterolateral structures act as stabilizers to varus & ER forces. They also are secondary stabilizers to posterior translation. • Arcuate “complex” refers to posterolateral stabilizing structures including: LCL, arcuate ligament, popliteus, & lateral gastrocnemius. NETTER’S CONCISE ORTHOPAEDIC ANATOMY 299

9 Leg/Knee • JOINTS Vastus Sartorius muscle Quadriceps Tendon of medialis femoris (vastus adductor magnus muscle Gracilis muscle medialis Quadriceps Tendon of muscle) Gastrocnemius muscle femoris tendon semitendinosus muscle (medial head) Medial Adductor magnus tendon Med. sup. Semimembranosus epicondyle genic. a. tendon of femur Semimembranosus Medial muscle and tendon Quadratus Bursa patellofemoral Posterior tendon ligament joint capsule Medial Patella meniscus Patella Medial (tibial) Tendons of: collateral ligament Medial expansion Sartorius muscle Medial patellar (retinaculum) of Gracilis muscle retinaculum Posterior tendon Semitendinosus oblique ligament muscle Medial Tibia patellotibial Semimembranosus Medial ligament bursa collateral Joint capsule Anserine bursa ligament Patellar ligament deep to Pes Patellar Tibial tuberosity Semitendinosus, anserinus tendon Gracilis and Sartorius tendons Tubercle Gastrocnemius muscle of tibia Soleus muscle Knee joint: medial view Ligaments of the knee: medial view LIGAMENTS ATTACHMENTS FUNCTION/COMMENT KNEE Sartorius Femorotibial Joint—Medial Structures First Layer—Superficial Becomes fascial layer at insertion at Pes Covers other tendons at Pes insertion Fascia Deep fascia from thigh continues to knee Blends with retinaculum (ant.) & capsule (post.) Superficial medial collateral (MCL) Second Layer—Middle Medial epicondyle to tibia (deep to Pes) Primary restraint to valgus force (esp. at 30°) Broad insertion is 5-7cm below joint line Secondary stabilizer to anterior translation & IR Posterior oblique Adductor tubercle (post. to MCL) to poste- Static stabilizer against valgus. Lax in flexion ligament (POL) rior tibia, PH of med. meniscus, & cap- but tightens dynamically due to semimembr. sule Medial patellofemoral Medial patella to medial femoral epicondyle Primary static stabilizer against patella lateraliza- ligament (MPFL) tion; may need repair/reconstruction after dx Medial patellar Continuous w/vastus fascia to tibia & patella Can also be injured in lateral patellar subluxation retinaculum Semimembranosus Inserts posteromedial on tibia Gives posteromedial support Deep medial Third Layer—Deep Stabilizes meniscus. Also known as medial collateral (MCL) capsular ligament or middle 1⁄3 capsular Meniscofemoral fibers Inserts on medial meniscus & tibia plateau ligament Meniscotibial fibers 2 sets of fibers: Femur to meniscus Tibia to meniscus Capsule Femur to tibia, extends 15mm below joint Reinforced by other posteromedial structures Medial meniscus Other Posterior horn is secondary stabilizer to ante- rior translation. Becomes 1° in ACL Attached firmly to medial tibial plateau via coronary ligaments Medial head of gastroc- Origin on the posteromedial femur Provides some minor additional dynamic nemius support • Gracilis and semitendinosus tendons are between layers 1 and 2 and act as secondary dynamic medial stabilizers. • The POL is a confluence of layers 2 and 3 tissues that are indistinct in the posteromedial aspect of the knee. 300 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Leg/Knee 9 Lateral MRI Quadriceps tendon Sagittal section Patella Articular (lateral to midline of knee) cartilage Subchondral Posterior Femur bone (of horn of Articularis genus muscle femur) lateral mensicus Quadriceps Fibula femoris tendon Iliotibial Suprapatellar fat body band (ITB) Suprapatellar Patellar ACL (synovial) bursa tendon Lateral meniscus Articular cavity Patella Lateral Anterior horn of Tibial plateau subtendinous lateral mensicus Subcutaneous bursa of prepatellar gastrocnemius Coronal MRI bursa muscle Synovial Synovial membrane membrane Patellar Articular PCL ligament cartilages Tibia Superficial Infrapatellar MCL fat pad Tibial tuberosity Deep MCL Subcutaneous infrapatellar bursa Deep (subtendinous) infrapatellar bursa Lateral meniscus Posterior cruciate Medial ligament (PCL) meniscus Deep medial Anterior cruciate collateral ligament (ACL) ligament Popliteus tendon (MCL) Lateral collateral Medial ligament (LCL) meniscus Lateral meniscus Superficial medial collateral Ligaments of knee: ligament (MCL) coronal (frontal) section NETTER’S CONCISE ORTHOPAEDIC ANATOMY 301

9 Leg/Knee • JOINTS Lateral compartment Medial compartment Medial meniscus visualized below Collagen fibers Lateral meniscus visualized. femoral condyle. Meniscus rises (finely woven) Varus stress raises meniscus with valgus stress, permitting from tibial condyle inspection beneath it Red-red zone Vascular zones Collagen fibers Red-white zone of meniscus (random orientation) White-white zone Circumferential collagen fibers Radial collagen fibers MENISCUS Structure • Fibrocartilage discs interposed in femorotibial joints between femoral condyles and tibial plateaus. Have a triangular cross section—thickest at the periphery, then tapering to a thin central edge. • Histologically made up of collagen (mostly type 1, also 2, 3, 5, 6), cells (fibrochondrocytes), water, proteoglycans, glycoproteins, elastin • 3 layers seen microscopically: 1. Superficial layer: woven collagen fiber pattern 2. Surface layer: randomly oriented collagen fiber pattern 3. Middle (deepest) layer: circumferential (longitudinal) oriented fibers. These fibers dissipate hoop stresses. Radial fibers. These fibers acts as “ties” to hold the circumferential fibers. • Vascular supply from superior and inferior medial and lateral geniculate arteries. They form perimeniscal plexus in synovium/capsule. Peripheral portion (10-30% medially, 10-25% laterally) is vascular via vessels from the perimenis- cal plexus. 3 zones: ‫ ؠ‬Red zone: 3mm from capsular junction (most tears will heal) ‫ ؠ‬Red/white zone: 3-5mm from capsular junction (some tears will heal) ‫ ؠ‬White zone: Ͼ5mm from capsular junction (most tears will not heal) The central, avascular 2⁄3 of the menisci receive nutrition from the synovial fluid • Medial meniscus: C-shaped, less mobile, firmly attached to tibia (via coronary ligaments) and capsule (via deep MCL) at midbody • Lateral meniscus: “circular”, more mobile, loose peripheral attachments, no attachment at popliteal hiatus (where pop- liteus tendon enters joint) Function 1. Load transmission and shock absorption: the menisci absorb 50% (in extension) or 85% (in flexion) of forces across femorotibial joint. The transmission of this load to the meniscus helps protect the articular cartilage 2. Joint congruity and stability: the menisci create congruity between the curved condyles and flat plateaus, which increases stability. The menisci (esp. PHMM) also act as secondary stabilizers to translation (esp. in the ligament- deficient knee) 3. Joint lubrication: the menisci help distribute synovial fluid across the articular surfaces. 4. Joint nutrition: the menisci absorb, then release synovial fluid nutrients for the cartilage. 5. Proprioception: nerve endings provide sensory feedback for joint position. 302 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Patellar ligament Inferior view JOINTS • Leg/Knee 9 Medial patellar retinaculum blended into joint capsule Posterior aspect lliotibial tract blended into lateral Suprapatellar synovial bursa MRI patellar retinaculum and capsule Synovial membrane (cut edge) Infrapatellar synovial fold Bursa Posterior cruciate ligament Subpopliteal recess Medial (tibial) collateral ligament Popliteus tendon (superficial and deep parts) Lateral (fibular) Medial condyle of femur collateral ligament Oblique popliteal ligament Bursa Semimembranosus tendon Lateral condyle of femur Anterior cruciate ligament Patellar tendon Arcuate popliteal ligament Retinaculum Lateral femoral condyle Popliteal artery Medial femoral condyle Patellar ligament Superior view Infrapatellar fat pad Anterior cruciate ligament lliotibial tract Anterior aspect blended into capsule Joint capsule MRI Superior articular surface Superior articular surface of tibial plateau (lateral facet) of tibial plateau (medial facet) Lateral meniscus Subpopliteal recess Synovial membrane Popliteus tendon Medial meniscus Bursa Fibular collateral ligament Medial collateral ligament Arcuate popliteal ligament (deep part bound to medial meniscus) Posterior meniscofemoral ligament Posterior cruciate ligament Oblique popliteal ligament Patellar tendon Semimembranosus tendon Lateral meniscus Medial meniscus LCL PCL Popliteus tendon Popliteal artery NETTER’S CONCISE ORTHOPAEDIC ANATOMY 303

9 Leg/Knee • JOINTS Vastus intermedius muscle Right knee in extension Suprapatellar pouch Vastus lateralis muscle Femur Articularis genus muscle lliotibial tract Vastus medialis muscle Lateral patellar retinaculum Rectus femoris tendon (becoming quadriceps Lateral epicondyle femoris tendon) of femur Lateral (fibular) collateral Patella Arthroscopic view ligament and bursa Medial epicondyle of femur shows patella above, trochlear groove of Biceps femoris tendon and its Medial patellar retinaculum femur below, inferior subtendinous bursa suprapatellar pouch Medial (tibial) in between Broken line indicates collateral ligament bursa deep to iliotibial tract Semitendinosus, Pes Insertion of iliotibial tract Gracilis and anserinus to Gerdy’s tubercle and Sartorius tendons oblique line of tibia Anserine bursa Common fibular (peroneal) nerve Head of fibula Medial condyle of tibia Fibularis (peroneus) Tibial tuberosity Patellar ligament Anteromedial longus muscle Gastrocnemius muscle compartment Extensor digitorum longus muscle Tibialis anterior muscle LIGAMENTS ATTACHMENTS FUNCTION/COMMENT KNEE Patellofemoral Joint Function • Composed of quadriceps tendon, patella, patellar tendon (ligament), and additional patella-stabilizing ligaments. • Extensor mechanism (of the knee) is primary role of this joint. The patella increases the moment arm from joint axis, increasing the mechanical advantage and quadriceps pull in extension. • Stability of the patella in the trochlear groove results from both bony morphology and static and dynamic stabilizers. Hypoplastic LFC or patellar ridge, a flat trochlea, or increased “Q” angle can all predispose the patella to dislocation. • The patella begins to engage the trochlea at 20° of flexion and is fully engaged by 40°. The articulation point moves proximally with increased flexion. The odd facet (far medial) of the patella articulates in full flexion. • Joint reaction forces can be very high in this joint: 3ϫ body weight with stairs, 7ϫ body weight with deep bending. The articular cartilage is up to 5mm (thickest in the body) to accommodate for these high forces. Structure Quadriceps tendon Quadriceps to superior pole of patella Can rupture with eccentric contraction (usu. Ͼ40y.o.) Patellar tendon (ligament) Inferior pole of patella to tibial Can rupture with eccentric tuberosity contraction (usu. Ͼ40y.o.) Patellofemoral ligaments Femoral epicondyles to medial/lateral Primary stabilizers of patella Medial (MPFL), lateral (LPFL) patella (esp. MPFL) Patellotibial ligaments (med. & lat.) Tibial plateaus to medial/lateral patella Minor patellar stabilizer Patellomeniscal ligaments (med. & lat.) Patella to periphery of menisci Secondary stabilizers of patella Patellar retinaculum (med. & lat.) Inserts on both the femur and tibia Minor patellar stabilizer Other • Patella position can evaluated on lateral radiograph (30° flexion) with Insall ratio (patella [diagonal] length/patellar tendon length). Normal ratio is 1.0 (0.8 to 1.2). Ͼ1.2 indicates patella baja, Ͻ0.8 indicates patella alta. • Dynamic stabilizers: quadriceps, adductor magnus, ITB, and vastus medialis and lateralis • Medial patellofemoral ligament (MPFL): primary restraint to lateral dislocation (most common) 304 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

JOINTS • Leg/Knee 9 Patellofemoral Joint MRI Patella Lateral retinaculum Medial Medial patellar facet Lateral patellar facet retinaculum Medial retinaculum Lateral retinaculum Trochlea Articular cartilage Normally, patella rides in groove between Femoral trochlea (groove) medial and lateral femoral condyles Anterior view with ligament attachments Superior view Iliotibial tract Posterior Cruciate Anterior ligaments Posterior ligament Posterior Lateral (fibular) of fibular head intercondylar area collateral ligament Medial (origin of posterior (tibial) Apex cruciate ligament) collateral ligament Head Posterior Intercondylar Biceps femoris Fibula eminence tendon Patellar ligament Anterior Tibia Head of fibula ligament Medial Tibial of fibular condyle Anterior ligament tuberosity head Superior of fibular head articular surface Anterior Lateral (medial facet) Gerdy’s tubercle border condyle Interosseous border Superior Anterior Medial Intercondylar Anterior border Interosseous articular surface Lateral tubercles Interosseous border membrane (lateral facet) Tibial tuberosity Lateral surface Lateral Anterior surface intercondylar area (origin of anterior Tibia cruciate ligament) Fibula Cross section Interosseous border Lateral surface Interosseous membrane Anterior border Anterior Medial Interosseous border Medial surface tibiofibular malleolus Tibia ligament Anterior border Medial border Medial (deltoid) Lateral surface Posterior surface Lateral malleolus ligament of ankle Fibula Medial surface Calcaneofibular ligament Posterior border Medial crest Anterior Posterior surface talofibular ligament LIGAMENTS ATTACHMENTS FUNCTION/COMMENT PROXIMAL TIBIOFIBULAR JOINT Anterior tibiofibular ligament Fibular head to anterior lateral tibia Broader and stronger than posterior ligament Posterior tibiofibular ligament Fibular head to posterior lateral tibia Weaker than anterior ligament Other Interosseous membrane Lateral tibia to medial fibula Stout fibrous membrane separates anterior & posterior compartments. Is disrupted in Maisonneuve fracture • This joint has minimal motion. Dislocation or disruption of this joint indicates high-energy trauma to the knee region. • For distal tibiofibular joint, please see Chapter 10, Foot/Ankle. NETTER’S CONCISE ORTHOPAEDIC ANATOMY 305

9 Leg/Knee • MINOR PROCEDURES Technique for injection of knee joint Quadriceps tendon Patella Intercondylar Tibia Femur notch Fibula Injection sites Patella tendon Meniscus Anterior view: points of needle insertion indicated Lateral view: needle in place Knee arthrocentesis STEPS INJECTION 1. Ask patient about allergies. 2. Place patient in seated position with knee flexed and hanging. 3. Prep skin (iodine/soap) over the anterior knee. 4. Prepare syringe with local/steroid mixture on 21/22 gauge needle. 5. Palpate the “soft spot” between the border of the patellar tendon, the tibial plateau, and the femoral condyle. 6. May locally anesthetize the skin over the “soft spot.” 7. Horizontally insert the needle into the “soft spot,” aiming approximately 30° to the midline toward the intercondylar notch. If the needle hits the condyle, redirect it more centrally into the notch. 8. Gently aspirate to confirm that you are not in a vessel. 9. Inject solution into knee. The fluid should flow easily. 10. Withdraw needle and dress the injection site. ASPIRATION/ARTHROCENTESIS 1. Ask patient about allergies. 2. Place patient supine with the knee fully extended. 3. Palpate the borders of the patella and femoral condyle. 4. Prep skin (iodine/antiseptic soap) over this area. 5. Insert needle, usually 21 or 18 gauge (for thick fluid), horizontally into suprapatellar pouch at level of superior pole of the patella. 6. Aspirate fluid into syringe (may use multiple syringes if needed). 7. Gently compress knee to “milk” fluid to the pouch for aspiration. 8. Withdraw needle and dress the injection site. 306 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

HISTORY • Leg/Knee 9 PCL Injury Sprains ACL Injury Usual causes include hyperextension injury, Usual cause is forceful impact on Usual cause is twisting of as occurs from stepping into hole, and direct posterolateral aspect of knee with foot hyperextended knee, as in blow to flexed knee anchored, producing valgus stress landing after basketball on knee joint jump shot QUESTION ANSWER CLINICAL APPLICATION 1. Age 2. Pain Young Trauma: ligamentous or meniscal injury, fracture Middle aged, elderly Arthritis a. Onset b. Location Acute Trauma: fx, dislocation, soft tissue (ligament/meniscus) injury, septic bursitis/arthritis c. Occurrence Chronic Arthritis, infection, tendinitis/bursitis, overuse, tumor 3. Stiffness Anterior Quadriceps or patellar tear or tendinitis, prepatellar bursitis, 4. Swelling patellofemoral dysfunction Posterior Meniscus tear (posterior horn), Baker’s cyst, PCL injury 5. Instability Lateral Meniscus tear (joint line), collateral lig. injury, arthritis, ITB syndrome 6. Trauma Medial Meniscus tear (joint line), collateral ligament injury, arthritis, pes bursitis 7. Activity Night pain Tumor, infection With activity Etiology of pain likely from joint 8. Neurologic sx 9. Systemic Without locking Arthritis, effusion (trauma, infection) 10. Hx of With locking/catching Loose body, meniscal tear (esp. bucket handle), arthritis, synovial plica arthritides Intraarticular Infection, trauma (OCD, meniscal tear, ACL/PCL injury, fracture) Extraarticular Collateral ligament injury, bursitis, contusion, sprain Acute (post injury) Acute (hours): ACL injury; subacute (day): meniscus injury, OCD Acute (without injury) Infection: prepatellar bursitis, septic joint Giving away/collapse Cruciate or collateral ligament injury/extensor mechanism injury Giving away & pain Patellar subluxation/dislocation, pathologic plica, OCD Mechanism: valgus MCL injury (ϩ/Ϫ terrible triad: MCL, ACL, medial meniscus injuries) Varus force LCL or posterolateral corner injury Flexion/posterior PCL injury (e.g., dashboard injury) Twisting Noncontact: ACL injury; Contact: multiple ligaments Cruciate ligament injury (esp. ACL), osteochondral fx, meniscal tear Popping noise Degenerative and overuse etiology None Cruciate (ACL #1) or collateral ligament Agility/cutting sports Patellofemoral etiology Running, cycling etc. Meniscus tear Squatting Distance able to ambulate equates with severity of arthritic disease Walking Neurologic disease, trauma (consider L-spine etiology) Numbness, tingling Infection, septic joint, tumor Fevers, chills Rheumatoid arthritis, gout, etc Multiple joints involved NETTER’S CONCISE ORTHOPAEDIC ANATOMY 307

9 Leg/Knee • PHYSICAL EXAM Quadriceps atrophy Prepatellar bursitis (housemaid’s knee) Q Line of incision Cellulitis and Q angle formed by intersection of induration lines from anterior superior iliac spine and from tibial tuberosity through mid- Osgood-Schlatter Disease Incision and drainage point of patella. Large Q angle pre- Clinical appearance. Prominence over tibial often necessary disposes to patellar subluxation. tuberosity partly due to soft-tissue swelling and partly to avulsed fragments EXAM TECHNIQUE/FINDINGS CLINICAL APPLICATION/DDX Gait Varus thrust INSPECTION Anterior Patella tracking Flexed knee gait Can indicate LCL or posterolateral corner injury/insufficiency Maltracking can lead to patellofemoral symptoms Knee alignment From tight Achilles tendon or hamstrings, can lead to patellofemoral symptoms Genu valgum (knock Normal knee alignment is clinically neutral (6° valgus radiographically). knee) Evaluate while weight-bearing. Variations can be developmental or post- Genu varum (bow leg) traumatic. Q angle Can predispose to lateral compartment DJD, patella instability/maltracking Swelling Can predispose to medial compartment DJD, ligamentous incompetency Angle from ASIS to mid-patella to tibial tubercle. Nl: male Յ10°, female Posterior Enlarged tibial tubercle Յ15°; increased angle predisposes to patellar subluxation, patellofemoral Lateral symptoms Mass Prepatellar: prepatellar bursitis (inflammatory or septic); intraarticular effu- Musculature Knee alignment sion: arthritis, infection, trauma (hemarthrosis): intraarticular fracture, Recurvatum meniscal tear, ligament rupture May be result of Osgood-Schlatter disease (esp. in adolescents) Patella position High-riding patella Baker’s cyst Low-riding patella Evaluated while weight-bearing Quadriceps Possible PCL injury Vastus medialis Best evaluated radiographically with Insall ratio (see Joints, Patellofemoral) Patella alta: can predispose to patella instability Patella baja: usually posttraumatic or postsurgical (possible arthrofibrosis) Atrophy can result from injury, postoperative, or neurologic conditions VMO atrophy may contribute to patellofemoral symptoms 308 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Joint line PHYSICAL EXAM • Leg/Knee 9 tenderness Iliotibial band Area of diffuse pain and tenderness Bulge sign Medial side of knee compressed or stroked proximally to move fluid away from medial compartment. Swelling and palpable sulcus above patella Lateral side is quickly Rupture of quadriceps femoris Assess for compressed or stroked distally; tendon at superior margin of effusion bulge appears medial to patella. patella EXAM TECHNIQUE/FINDINGS CLINICAL APPLICATION/DDX Bony structures Soft tissues PALPATION Patella Tenderness at distal pole: tendinitis (jumper’s knee) Tibial tubercle Tenderness with Osgood-Schlatter disease Quadriceps tendon Defect: tendon rupture; tenderness: tendinitis Patellar tendon Defect: tendon rupture; tenderness (esp. at insertion): tendinitis (jumper’s knee) Compress suprapatellar pouch Ballotable patella (effusion): arthritis, trauma, infection Prepatellar bursa Edematous/tender bursae indicate correlating bursitis Pes anserine bursa Tenderness indicates bursitis Retinaculum/plica Thickened, tender plica is pathologic Medial joint line and MCL Tenderness: medial meniscus tear or MCL injury Lateral joint line and LCL Tenderness: lateral meniscus tear or LCL injury Iliotibial band/LFC (anterolateral knee) Pain or tightness is pathologic Popliteal fossa Mass consistent with Baker’s cyst, popliteal aneurysm Compartments of leg (anterior, poste- Firm or tense compartment: compartment syndrome rior, lateral) NETTER’S CONCISE ORTHOPAEDIC ANATOMY 309

9 Leg/Knee • PHYSICAL EXAM Acute Anterior Compartment Syndrome 5 Ps, often early manifestations Paresthesia of compartment syndrome Paresis (foot drop) Pain Hyperextension Septic bursitis Pulseless Pallor 0˚ 0˚ Extension (Limited extension) (Normal extension) Flexion 30˚ Limited range of motion Normal range of (Limited motion of knee joint flexion) 90˚ 135˚ to 145˚ 135˚ to 145˚ (Normal flexion) EXAM TECHNIQUE/FINDINGS CLINICAL APPLICATION/DDX Flexion/extension RANGE OF MOTION Tibial IR & ER Supine: heel to buttocks, Normal: flex 0 to 125-135°, extend 0 to 5-15° then straight Flexion contracture: common in OA/DJD Femoral nerve/saphenous (L4) Extensor lag (final 20º difficult): weak quadriceps Peroneal nerve (L5) Note patellar tracking, pain, Decreased extension with effusion and crepitus Abnormal tracking leads to anterior knee pain Lateral sural Superficial branch Stabilize femur, rotate tibia Normal 10-15° IR/ER Tibial nerve (S1) Medial sural NEUROVASCULAR Sural nerve Sensory Femoral nerve (L2-4) Sciatic: Tibial (L4-S3) Medial leg Deficit indicates corresponding nerve/root lesion Peroneal (L4-S3) Tibial nerve (S1) Deficit indicates corresponding nerve/root lesion Peroneal (deep) n. (L4) Peroneal (superficial) n. (L5) Proximal lateral leg Distal lateral leg Reflex (L4) Deficit indicates corresponding nerve/root lesion Pulse Proximal posterolateral leg Distal posterolateral leg Deficit indicates corresponding nerve/root lesion Motor Knee extension Weakness = Quadriceps or nerve/root lesion Knee flexion Weakness = Biceps (LH) or nerve/root lesion Knee flexion Weakness = Biceps (SH) or nerve/root lesion Foot plantarflexion Weakness = TP, FHL, FDL, or nerve/root lesion Foot dorsiflexion Weakness = TA or nerve/root lesion Hallux dorsiflexion Weakness = EHL or nerve/root lesion Other Patellar Hypoactive/absence indicates L4 radiculopathy Hyperactive may indicate UMN/myelopathic condition Popliteal Diminished pulse can result from trauma 310 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Apprehension (Fairbank) PHYSICAL EXAM • Leg/Knee 9 test As examiner displaces patella laterally, patient Anterior drawer test feels pain and forcefully Patient supine on table, hip flexed 45°, knee 90°. Examiner sits on patient’s contracts quadriceps foot to stabilize it, places hands on each side of upper calf and firmly pulls femoris muscle. tibia forward. Movement of 5 mm or more is positive test. Result also compared with that for normal limb, which is tested first. Lachman test With patient’s knee bent 20˚–30˚, examiner’s hands grasp limb over distal femur and proximal tibia. Tibia pulled forward with femur stabilized. Movement of 5 mm or more than that in normal limb indicates rupture of anterior cruciate ligament. EXAM TECHNIQUE CLINICAL APPLICATION/DDX Patella displacement SPECIAL TESTS Patella apprehension Patellofemoral Joint J sign Patella compression/grind Translate patella medially & laterally Divide patella into 4 quadrants. Patella should translate 2 quadrants in both directions. De- Joint line tenderness creased mobility indicates a tight retinaculum. McMurray Apley’s compression Relax knee, push patella laterally Pain/apprehension of subluxation: patellar in- Lachman stability or medial retinaculum/MPFL injury Anterior drawer Actively extend knee from flexed po- Lateral displacement of patella in full exten- Pivot shift sition sion: maltracking Extend knee, fire quads, compress Pain: chondromalacia, OCD, PF arthritis/DJD patella of patella Meniscus Palpate both joint lines Most sensitive exam for meniscal tear when tender (see page 309) Flex/varus/ER knee, then extend Pop or pain suggests medial, meniscal tear Flex/valgus/IR knee, then extend Pop or pain suggests lateral, meniscal tear Prone, knee 90°, compress & rotate Pain or pop indicates meniscal tear Anterior Cruciate Ligament Flex knee 20-30°, anterior force on Laxity indicates ACL injury. Most sensitive tibia exam for ACL rupture. Grade 1: 0-5mm, 2: 6- 10mm, 3: Ͼ10mm; A: good, B: no endpoint Flex knee 90°, anterior force on tibia Laxity/anterior translation: ACL injury Supine, extend knee, IR, valgus force Clunk with knee flexion indicates ACL injury. (If on proximal tibia, then flex knee ACL is deficient, the tibia starts subluxated and reduces with flexion, causing the clunk.) NETTER’S CONCISE ORTHOPAEDIC ANATOMY 311

9 Leg/Knee • PHYSICAL EXAM Pivot shift test for anterolateral knee instability Patient supine and relaxed. Examiner lifts heel of foot to flex hip 45˚ keeping knee fully extended; grasps knee with other hand, placing thumb beneath head of fibula. Examiner applies strong internal rotation to tibia and fibula at both knee and ankle while lifting proximal fibula. Knee permitted to flex about 20˚; examiner then pushes medially with proximal hand and pulls with distal hand to produce a valgus force at knee As internal rotation, valgus force, and forward displacement of lateral tibial condyle maintained, knee passively flexed. If anterior subluxation of tibia (anterolateral instability) present, sudden visible, audible, and palpable reduction occurs at about 20˚–40˚ flexion. Test positive if anterior cruciate ligament ruptured, especially if lateral capsular ligament also torn Posterior drawer test Posterior sag sign Leg drops backward Procedure same as for anterior drawer test, 312 NETTER’S CONCISE ORTHOPAEDIC ANATOMY except that pressure on tibia is backward instead of forward

PHYSICAL EXAM • Leg/Knee 9 Varus and valgus tests Patient supine on table, relaxed, leg over edge of table, flexed about 30˚. With one hand fixing thigh, examiner places other hand just above ankle and applies valgus stress. Degree of mobility compared with that of uninjured side, which is tested first. For varus stress test, direction of pressure reversed. External rotation at 30° and 90° (dial test). Test may be performed prone or supine (shown). External rotation recurvatum test EXAM TECHNIQUE CLINICAL APPLICATION/DDX Posterior drawer SPECIAL TESTS Posterior sag Quadriceps active Posterior Cruciate Ligament Reverse pivot shift Flex knee 90°, posterior force on tibia Posterior translation: PCL injury Valgus stress Varus stress Supine, hip 45°, knee 90°, view Posterior translation of tibia (by gravity) on femur laterally indicates PCL injury Prone ER at 30° & 90° (Dial) Supine, knee 90°, fire quadriceps Posteriorly subluxated tibia translates anteriorly if ER recurvatum PCL is deficient Slocum Posterior lateral Supine, flex knee 45°, ER, valgus Clunk with knee extension indicates PCL injury. (If drawer force on proximal tibia, then extend PCL is deficient, the tibia is subluxated posteriorly, Posterior medial knee then reduces w/extension, causing the clunk.) drawer Collateral Ligaments Lateral force to knee at 30°, then 0° Laxity at 30°—MCL injury; 0°—MCL and cruciate ligament injury Medial force to knee at 30°, then 0° Laxity at 30°— LCL injury; 0°—LCL and cruciate ligament injury Other Prone, ER both knees at 90°, then Increased ER at 30°: posterolateral corner (PLC) in- 30° (can be done supine) jury; at 90° PLC & PCL injuries Supine, legs straight, raise legs by Recurvatum, varus, and IR of knee indicates PLC toes (ϩ/Ϫ PCL) injury Knee 90°, IR tibia 30°, anterior force Displacement: anterior & lateral injury (ACL & PLC)) Knee 90°, ER tibia 30°, anterior force Displacement: anterior & medial inj. (ACL, MCL, POL) Knee 90º, ER tibia 15°, posterior Laxity indicates posterolateral corner and/or PCL force injury Knee 90°, IR tibia 30°, posterior Laxity indicates PCL and medial ligament (MCL, POL) force injury NETTER’S CONCISE ORTHOPAEDIC ANATOMY 313

9 Leg/Knee • ORIGINS AND INSERTIONS Anterior view Posterior view Plantaris muscle Gastrocnemius muscle Iliotibial tract Gastrocnemius muscle (lateral head) (medial head) Popliteus muscle Biceps femoris muscle Semimembranosus Tibialis posterior muscle muscle Fibularis (peroneus) Sartorius muscle Pes anserinus Flexor hallucis longus muscle Gracilis muscle longus muscle Semitendinosus Popliteus Extensor muscle muscle Fibularis (peroneus) digitorum brevis muscle longus muscle Quadriceps femoris Soleus Plantaris muscle muscle via muscle Soleus and Extensor hallucis patellar ligament gastrocnemius longus muscle Tibialis anterior Flexor muscles via muscle digitorum calcaneal (Achilles) Fibularis longus muscle tendon (peroneus) Origins brevis muscle Insertions Fibularis (peroneus) Fibularis Note: Attachments longus muscle (peroneus) of intrinsic muscles tertius muscle of foot not shown Flexor digitorum Fibularis Tibialis longus muscle (peroneus) posterior muscle brevis muscle Tibialis Fibularis anterior muscle (peroneus) tertius muscle Extensor digitorum Flexor hallucis longus muscle longus muscle Extensor hallucis longus muscle LATERAL FEMORAL MEDIAL FEMORAL FIBULAR HEAD PROXIMAL TIBIA CONDYLE CONDYLE Tibialis anterior (Gerdy’s tub.) Lateral gastrocnemius ORIGINS Extensor digitorum longus Plantaris Popliteus (ant. & inf. to LCL) Medial gastrocnemius Soleus Quadriceps (tibial tubercle) Ligaments: Iliotibial band (Gerdy’s tub.) Pes tendons (sar, grac, semi) Lateral collateral lig. (LCL) Semimembranosus (postmed.) Popliteus (posteriorly) INSERTIONS Ligaments: Adductor magnus (ad- Biceps femoris Medial collateral lig. (MCL) ductor tub.) Ligaments: Ligaments: Medial collateral Lateral collateral lig. (LCL) Popliteofibular ligament lig. (MCL) Arcuate ligament Fabellofibular ligament 314 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

MUSCLES • Leg/Knee 9 Deep fascia of leg Interosseous membrane Anterior compartment Tibia Anterior intermuscular septum Lateral compartment Deep posterior compartment Fibula Transverse intermuscular Anterolateral Posterior intermuscular septum septum incision Deep fascia of leg Superficial posterior comparatment Medial incision Cross section just above middle of leg Tibialis anterior muscle Anterior tibial artery and veins Extensor hallucis longus muscle and deep fibular (peroneal) nerve Extensor digitorum longus muscle Superficial fibular (peroneal) nerve Tibia Anterior intermuscular septum Interosseous membrane Great saphenous vein and saphenous nerve Deep fascia of leg Tibialis posterior muscle Fibularis (peroneus) longus muscle Flexor digitorum longus muscle Fibularis (peroneus) brevis muscle Fibular (peroneal) artery and veins Posterior intermuscular septum Posterior tibial artery and veins and tibial nerve Fibula Lateral sural cutaneous nerve Flexor hallucis longus muscle Transverse intermuscular septum Deep fascia of leg Soleus muscle Plantaris tendon Gastrocnemius muscle (lateral head) Gastrocnemius muscle (medial head) Sural communicating branch Medial sural cutaneous nerve of lateral sural cutaneous nerve Small saphenous vein COMPARTMENT MUSCLES NEUROVASCULAR STRUCTURE Anterior COMPARTMENTS (4) Lateral Superficial posterior Tibialis anterior (TA) Deep peroneal nerve Deep posterior Extensor hallucis longus (EHL) Anterior tibial artery and vein Extensor digitorum longus (EDL) Anterolateral Peroneus tertius Medial Peroneus longus Superficial peroneal nerve Peroneus brevis Gastrocnemius None Soleus Plantaris Posterior tibialis (PT) Tibial nerve Flexor hallucis longus (FHL) Posterior tibial artery and vein Flexor digitorum longus (FDL) Peroneal artery and vein Popliteus FASCIOTOMIES Centered over the intermuscular septum between the anterior and lateral compartments Centered over the posterior tibial border/septum between the superficial and deep posterior compartments NETTER’S CONCISE ORTHOPAEDIC ANATOMY 315

9 Leg/Knee • MUSCLES Vastus medialis muscle Patella Vastus lateralis muscle Superior medial genicular artery Rectus femoris tendon (becoming Tibial collateral ligament quadriceps femoris tendon) Medial patellar retinaculum Inferior medial genicular artery Iliotibial tract Infrapatellar branch (cut) of Superior lateral genicular artery Saphenous nerve (cut) Joint capsule Lateral patellar retinaculum Patellar ligament Biceps femoris tendon Insertion of sartorius muscle Tibial tuberosity Inferior lateral genicular artery Tibia Common fibular (peroneal) nerve Gastrocnemius muscle Head of fibula Soleus muscle Fibularis (peroneus) longus muscle Extensor hallucis longus muscle Tibialis anterior muscle Superficial fibular (peroneal) nerve (cut) Fibularis (peroneus) brevis muscle Extensor digitorum longus muscle Fibula Medial malleolus Superior extensor retinaculum Tibialis anterior tendon Medial branch of deep fibular (peroneal) nerve Lateral malleolus Extensor hallucis longus tendon Inferior extensor retinaculum Extensor hallucis brevis tendon Extensor digitorum longus tendons Dorsal digital branches Fibularis (peroneus) tertius tendon of deep fibular (peroneal) nerve Extensor digitorum brevis tendons Dorsal digital nerves MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT Tibialis anterior Proximal lateral ANTERIOR COMPARTMENT (TA) tibia, (Gerdy’s tubercle) Med. cuneiform, plantar Deep Dorsiflex, invert Test L4 motor Extensor hallucis foot function longus (EHL) Medial fibula, 1st metatarsal base peroneal interosseous Extensor digito- membrane Base of distal phalanx of Deep Dorsiflex, extend Test L5 motor rum longus (EDL) Lateral tibia con- great toe peroneal great toe function Peroneus tertius dyle & proximal fibula Base of middle & distal Deep Dorsiflex, extend Single tendon lateral 4 toes divides into Distal fibula, phalanges (4 toes) peroneal four tendons interosseous Dorsiflex, evert membrane Base of 5th metatarsal Deep foot (weak) Often adjoined peroneal to the EDL 316 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Biceps Long head MUSCLES • Leg/Knee 9 femoris Short head muscle Tendon Vastus lateralis muscle Iliotibial tract Fibular collateral ligament Quadriceps femoris tendon Superior lateral genicular artery Common fibular Patella (peroneal) nerve Lateral patellar retinaculum Inferior lateral genicular artery Lateral condyle of tibia Patellar ligament Head of fibula Tibial tuberosity Gastrocnemius muscle Tibialis anterior muscle Soleus muscle Extensor digitorum longus muscle Fibularis (peroneus) longus muscle and tendon Superficial fibular (peroneal) nerve (cut) Fibularis (peroneus) brevis muscle and tendon Extensor digitorum longus tendon Extensor hallucis longus muscle and tendon Fibula Superior extensor retinaculum Inferior extensor retinaculum Lateral malleolus Extensor digitorum brevis muscle Calcaneal (Achilles) tendon Extensor hallucis longus tendon Extensor digitorum longus tendons (Subtendinous) bursa Fibularis (peroneus) brevis tendon of tendocalcaneus Fibularis (peroneus) tertius tendon Superior fibular 5th metatarsal (peroneal) retinaculum bone Inferior fibular (peroneal) retinaculum Fibularis (peroneus) longus tendon passing to sole of foot MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT Peroneus Proximal lateral LATERAL COMPARTMENT Plantar flex foot Test S1 motor func- longus fibula (1st ray) tion; runs under the Plantar medial cu- Superficial foot Peroneus Distal lateral neiform, 1st meta- peroneal Evert foot brevis fibula tarsal base Can cause avulsion fx at base of 5th MT; Base of 5th meta- Superficial has most distal tarsal peroneal muscle belly NETTER’S CONCISE ORTHOPAEDIC ANATOMY 317

9 Leg/Knee • MUSCLES Iliotibial tract Biceps femoris muscle Semitendinosus muscle Tibial nerve Semimembranosus muscle Common fibular (peroneal) nerve Superior lateral genicular artery Gracilis muscle Plantaris muscle Popliteal artery and vein Gastrocnemius muscle (lateral head) Lateral sural cutaneous nerve (cut) Sartorius muscle Medial sural cutaneous nerve (cut) Superior medial genicular artery Gastrocnemius muscle (medial head) Nerve to soleus muscle Small saphenous vein Gastrocnemius muscle Soleus muscle Soleus muscle Plantaris tendon Flexor digitorum longus tendon Fibularis (peroneus) longus tendon Tibialis posterior tendon Fibularis (peroneus) brevis tendon Calcaneal (Achilles) tendon Posterior tibial artery and vein Lateral malleolus Tibial nerve Superior fibular (peroneal) retinaculum Fibular (peroneal) artery Medial malleolus Calcaneal branches of fibular (peroneal) artery Flexor hallucis longus tendon Calcaneal tuberosity Flexor retinaculum Calcaneal branch of posterior tibial artery MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT Gastrocnemius Soleus SUPERFICIAL POSTERIOR COMPARTMENT Test S1 motor function; two Plantaris heads, fabella is in tendon Lateral and me- Calcaneus Tibial Plantar flex foot of lateral head dial femoral (via Achilles condyles tendon) Fuses to gastrocnemius at Achilles tendon Posterior fibular Calcaneus Tibial Plantar flex foot Long tendon can be harvested head/soleal line (via Achilles for tendon reconstruction of tibia tendon) Lateral femoral Calcaneus Tibial Plantar flex foot supracondylar (weak) line 318 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Superior medial genicular artery MUSCLES • Leg/Knee 9 Gastrocnemius muscle (medial head) (cut) Superior lateral genicular artery Sural (muscular) branches Plantaris muscle (cut) Popliteal artery and tibial nerve Gastrocnemius muscle (lateral head) (cut) Fibular collateral ligament Tibial collateral ligament Biceps femoris tendon (cut) Semimembranosus tendon (cut) Inferior lateral genicular artery Inferior medial genicular artery Head of fibula Common fibular (peroneal) nerve Popliteus muscle Posterior tibial recurrent artery Soleus muscle (cut and reflected) Tendinous arch of soleus muscle Anterior tibial artery Posterior tibial artery Fibular (peroneal) artery Flexor digitorum longus muscle Flexor hallucis longus muscle (retracted) Tibial nerve Fibular (peroneal) artery Tibialis posterior muscle Interosseous membrane Calcaneal (Achilles) tendon (cut) Perforating branch of fibular Flexor digitorum longus tendon Communicating branch (peroneal) artery Tibialis posterior tendon Fibularis (peroneus) longus tendon Medial malleolus and posterior medial malleolar branch of posterior tibial artery Fibularis (peroneus) brevis tendon Lateral malleolus and posterior lateral Flexor retinaculum malleolar branch of fibular (peroneal) artery Medial calcaneal branches of Superior fibular (peroneal) retinaculum posterior tibial artery and tibial nerve Lateral calcaneal branch of fibular (peroneal) artery Tibialis posterior tendon Lateral calcaneal branch of sural nerve Medial plantar artery and nerve Lateral plantar artery and nerve Inferior fibular (peroneal) retinaculum Flexor hallucis longus tendon Fibularis (peroneus) brevis tendon 1st metatarsal bone Fibularis (peroneus) longus tendon Flexor digitorum longus tendon 5th metatarsal bone MUSCLE ORIGIN INSERTION NERVE ACTION COMMENT Popliteus DEEP POSTERIOR COMPARTMENT Origin is intraarticular; primary restraint to Flexor hallucis Lateral femoral con- Proximal poste- Tibial IR tibia/knee (dur- ER of knee longus (FHL) dyle (anterior and rior tibia ing “swing” Test S1 motor function distal to LCL) phase) Flexor digitorum At ankle, tendon is longus (FDL) Posterior fibula Base of distal Tibial Plantar flex great just anterior to tibial phalanx of toe artery Tibialis posterior great toe Tendon rupture/ (TP) degen. can cause Posterior tibia Bases of distal Tibial Plantar flex lateral acquired flat foot phalanges of 4 toes 4 toes Posterior tibia, fibula, Plantar navicular Tibial Plantar flex and in- interosseous mem- cuneiforms, MT vert foot (in “heel brane bases off” phase) NETTER’S CONCISE ORTHOPAEDIC ANATOMY 319

9 Leg/Knee • NERVES Infrapatellar branch of saphenous nerve Medial cutaneous nerves of leg (branches of saphenous nerve) Tibial nerve LUMBAR PLEXUS Tibial nerve Common (L4, 5, S1, 2, 3) fibular Posterior Division (peroneal) Medial sural nerve Saphenous (L2-4): Branch of femoral cutaneous nerve (cut) nerve, enters leg posteromedially, Articular superficial to sartorial fascia (at risk Articular branches branch in direct medial approach, e.g., MMR). It then gives off infrapatellar Plantaris muscle Lateral sural branch (at risk in anteromedial & cutaneous midline approaches, e.g., ACLR), Gastrocnemius nerve (cut) and descends in medial leg. muscle (cut) Sensory: Infrapatellar region: via Nerve to popliteus muscle infrapatellar branch Medial leg: via medial Popliteus muscle cutaneous nerves Interosseous nerve of leg Motor: None (in leg) Soleus muscle (cut and SACRAL PLEXUS partly retracted) Anterior Division Flexor digitorum longus muscle Tibial (L4-S3): descends b/w heads of gastrocnemius into leg, posterior Tibialis posterior muscle to posterior tibialis muscle (in deep posterior compartment) to ankle just Flexor hallucis posterior to medial malleolus b/w longus muscle FDL and FHL tendons. Sural nerve (cut) Sensory: Proximal posterolateral leg: Lateral calcaneal branch via medial sural nerve (from sural n.) Medial calcaneal Motor: • Super. post. compartment branch (from tibial n.) ‫ ؠ‬Plantaris ‫ ؠ‬Gastrocnemius Flexor retinaculum (cut) ‫ ؠ‬Soleus: via n. to soleus Lateral dorsal • Deep post. compartment cutaneous nerve ‫ ؠ‬Popliteus: via n. to popliteus ‫ ؠ‬Posterior tibialis (PT) ‫ ؠ‬Flexor digitorum longus ‫ ؠ‬Flexor hallucis longus 320 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

NERVES • Leg/Knee 9 Cutaneous innervation From Common fibular Lateral sural sciatic (peroneal) nerve cutaneous nerve via lateral sural nerve cutaneous nerve Superficial Medial sural fibular cutaneous nerve (peroneal) nerve Superficial fibular SACRAL PLEXUS (peroneal) nerve Posterior Division Sural nerve Common peroneal (L4-S2): divides Tibial nerve from sciatic nerve in distal posterior via medial thigh, runs posteroinferior to biceps calcaneal femoris, around fibular neck (can be branches compressed or injured), then divides into 2 branches. Common fibular Common Peroneal Nerve (peroneal) nerve Sensory: Proximal lateral leg: via (phantom) Lateral sural lateral sural nerve cutaneous nerve Biceps femoris (phantom) Motor: None (before dividing) tendon Articular branches Recurrent Deep peroneal: runs in anterior com- Common fibular articular nerve partment of leg with anterior tibial (peroneal) nerve Extensor digitorum artery, posterior to tibialis anterior (L4, 5, S1, 2) longus muscle (cut) on interosseous membrane. Deep fibular Head of fibula (peroneal) nerve Sensory: None (in leg) Tibialis Motor: • Anterior compartment Fibularis anterior muscle (peroneus) ‫ ؠ‬Tibialis anterior (TA) longus muscle Extensor digitorum ‫ ؠ‬Extensor hallucis longus (cut) longus muscle ‫ ؠ‬Ext. digitorum longus ‫ ؠ‬Peroneus tertius Superficial fibular Extensor hallucis (peroneal) nerve longus muscle Superficial peroneal: Runs in lateral compartment of leg, crosses anteri- Branches of Lateral branch of orly 12cm above lateral malleolus (in- lateral sural deep fibular jured in lateral ankle approach, e.g., cutaneous (peroneal) nerve to ankle ORIF) to dorsal foot, then di- nerve Extensor hallucis brevis vides into 2 branches. Fibularis and (peroneus) Extensor digitorum Sensory: Anterolateral leg longus muscle brevis muscles Motor: • Lateral compartment Fibularis Medial branch of ‫ ؠ‬Peroneus longus (PL) (peroneus) deep fibular ‫ ؠ‬Peroneus brevis (PB) brevis muscle (peroneal) nerve Other Medial dorsal cutaneous nerve Sural: Formed from medial sural cu- taneous (tibial nerve) & lateral sural Intermediate dorsal cutaneous (peroneal nerve), runs cutaneous nerve subcutaneously in posterolateral leg, crosses Achilles tendon 10cm above Inferior extensor insertion, then to lateral heel. retinaculum (partially cut) Sensory: Posterolateral distal leg Motor: None Lateral dorsal cutaneous nerve (branch of sural nerve) Dorsal digital nerves NETTER’S CONCISE ORTHOPAEDIC ANATOMY 321

9 Leg/Knee • ARTERIES Descending genicular artery Articular branch Femoral artery passing Saphenous branch through adductor hiatus Superior medial genicular artery Superior lateral genicular artery Patellar anastomosis Popliteal artery (phantom) Inferior lateral genicular artery Middle genicular artery (phantom) (partially in phantom) Posterior tibial recurrent artery Inferior medial genicular artery (phantom) (partially in phantom) Circumflex fibular branch Anterior tibial recurrent artery Anterior tibial artery Posterior tibial artery (phantom) Interosseous membrane Fibular (peroneal) artery (phantom) COURSE BRANCHES COMMENT/SUPPLY POPLITEAL ARTERY Begins at adductor hiatus and runs Superior medial and lateral geniculate SLGA at risk in lateral release through the popliteal fossa, posterior Inferior medial and lateral geniculate ILGA separates lateral knee layer 3 to PCL (can be injured here), then ligaments/structures divides at the popliteus muscle Middle geniculate Supplies ACL, PCL, and synovium Anterior and posterior tibial arteries Terminal branches of popliteal artery • All four geniculate arteries anastomose around the knee and the patella. ANTERIOR TIBIAL ARTERY Passes b/w the two heads of the Anterior tibial recurrent Supplies and anastomoses at knee posterior tibialis into the anterior Circumflex fibular Supplies fibular head and lateral knee compartment and lies on interosse- Anterior medial and lateral malleolar Supplies anterior portion of malleoli ous membrane w/deep peroneal n. Dorsalis pedis Terminal branch in foot • Supplies muscles of the anterior compartment of the leg POSTERIOR TIBIAL ARTERY Runs with tibial nerve in deep poste- Posterior tibial recurrent Supplies and anastomoses at knee rior compartment, posterior to pos- Peroneal artery Supplies lateral compartment terior tibialis muscle to the ankle, Perforating muscular branches To muscles of post. compartments where it lies between the FDL and Posterior medial malleolar Supplies posterior medial malleolus FHL tendons posterior to the medial Medial calcaneal Supplies medial calcaneus/heel malleolus (pulse is palpable here). Medial and lateral plantar Terminal branches in the foot • Supplies muscles of the superficial and deep posterior compartments of the leg PERONEAL ARTERY Branches from posterior tibial artery, Posterior lateral malleolar Supplies posterior lateral malleolus runs between PT & FHL muscles in Lateral calcaneal Supplies lateral calcaneus/heel posterior compartment • Supplies muscles of the lateral compartment of the leg • See muscle pages 315-319 for additional pictures of the arteries 322 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

Progressive DISORDERS • Leg/Knee 9 stages in joint Joint Pathology in Osteoarthritis pathology Knee joint opened anteriorly Early degenerative Further erosion of Cartilages almost completely reveals large erosion of articular changes with surface cartilages, pitting, and destroyed and joint space cartilages of femur and patella fraying of articular cleft formation. Hyper- narrowed. Subchondral bone with cartilaginous excrescences cartilages trophic changes of bone irregular and eburnated; spur at intercondylar notch at joint margins formation at margins. Fibrosis of joint capsule Joint Pathology in Rheumatoid Arthritis 1 2 34 Knee joint opened anteriorly, patella reflected downward. Thickened Progressive stages in joint pathology.1. Acute inflammation of synovial membrane synovial membrane inflamed; poly- (synovitis) and beginning proliferative changes. 2. Progression of inflammation with poid outgrowths and numerous villi pannus formation; beginning destruction of cartilage and mild osteoporosis. 3. Sub- (pannus) extend over rough articular sidence of inflammation; fibrous ankylosis. 4. Bony ankylosis; advanced osteoporosis cartilages of femur and patella DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT • Primary/idiopathic or sec- ARTHRITIS 1. NSAIDs, activity modification ondary (e.g., posttrau- 2. Physical therapy, brace, cane matic) Osteoarthritis 3. Glucocorticosteroid injections 4. Unicompartmental • Loss/deterioration of ar- Hx: Older, decreasing XR ticular cartilage activity level. Pain w/ ‫ ؠ‬HTO weight-bearing and 1. Arthritis series ‫ ؠ‬Unicompartment arthroplasty • Can affect 1 (medial #1) activities ‫ ؠ‬Joint space narrowing 5. Tricompartmental: Total knee or all 3 compartments in PE: Effusion, joint line ‫ ؠ‬Osteophytes arthroplasty (TKA) knee tenderness, ϩ/Ϫ con- ‫ ؠ‬Subchondral sclerosis tracture or deformity ‫ ؠ‬Subchondral cysts 1. Early: manage medically • Multiple types: rheuma- (varus #1) 2. Late toid, gout, seronegative 2. Alignment views (e.g., Reiter’s) ‫ ؠ‬Nonop: like osteoarthritis Inflammatory ‫ ؠ‬Synovectomy • In RA, synovitis/pannus ‫ ؠ‬Total knee arthroplasty formation destroys carti- Hx: Usually younger XR: Arthritis series: joint lage & eventually whole pts. Pain, often multi- narrowing, joint ero- joint. ple joints sions, ankylosis, joint PE: Effusion, ϩ/Ϫ destruction warmth, decr. ROM & LABS: CBC, RF, ANA, CRP, deformity crystals, culture NETTER’S CONCISE ORTHOPAEDIC ANATOMY 323

9 Leg/Knee • DISORDERS Patellofemoral stress syndrome With knee extended, patella As knee flexes, tension lies above and between in quadriceps femoris femoral condyles in contact tendon and patellar tendon with suprapatellar fat pad compresses patella against femoral condyles Chondromalacia Arthroscopic view shows Chondromalacia of patella with Iliotibial tract friction fragmented patellar cartilage “kissing” lesion on femoral condyle syndrome Lateral patellar compression syndrome As knee flexes and extends, iliotibial tract Patella glides back and forth over lateral femoral epicondyle, causing friction Preoperative x-ray showing lateral Lateral patellar Arthroscopic view of transcutaneous tilt of patella. retinaculum release of lateral retinaculum Line indicates extent of release DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT ANTERIOR KNEE PAIN • NSAIDs, activity modification • Physical therapy: ROM, Patellofemoral Syndrome quad. strengthening, ham- • Pain in patellofemoral joint Hx: Young female XR: 4 views: string stretching, ϩ/Ϫ foot • Contributing factors: overuse, and athletes. Pain AP & notch: eval. for orthoses w/activities (esp. run- OCD, OA • Patella realignment subtle instability or malalign- ning, stairs) and pro- Lateral: OA & Insall (if malalignment is present) ment, quadriceps weakness longed sitting ratio • Chondromalacia may be PE: ϩpatella compres- Sunrise: subluxation or • NSAIDs, activity modification present, but not necessarily sion, ϩ/Ϫ incr. • Physical therapy Q angle and/or J-sign tilt, OA, OCD • Arthroscopic debridement/ Chondromalacia Patellae chondroplasty may help • Softening or wear of the ar- Hx: Usually younger pts.; XR: 4 view: evaluate • PT: stretch lateral tissues, ticular cartilage of the patella pain, often multiple jts. like PFS (see above) quad. strengthening ϩ/Ϫ PE: Effusion, decr. ROM taping or centralizing brace • Term often misused to imply & deformity any anterior knee pain • Arthroscopic lateral release Lateral Patellar Compression Syndrome • NSAIDs, activity modifica- tion, stretching (ITB) • Overloading of lateral facet Hx: Usually younger pts.; XR: 3 or 4 views during flexion anterior knee pain Sunrise/merchant: • Partial excision (rare) PE: PF pain, decreased evaluate for lateral • Due to tight lateral structures mobility/patella glide patella tilt (esp. lateral retinaculum) Iliotibial Band Syndrome • ITB rubs on lateral femoral Hx: Pain w/activity XR: AP/lateral: normal, condyle PE: Lateral femoral con- r/o tumor • Common w/runners/cyclists dyle; TTP (knee at 30°) 324 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Leg/Knee 9 Patella (turned up) Synovial plica Opening to suprapatellar pouch Medial femoral Suprapatellar plica (usually condyle asymptomatic) Lateral gutter Lateral plica (asymptomatic) Medial (shelf) Lateral femoral condyle 30˚ plica (symptomatic) At 30˚ flexion, Anterior cruciate ligament plica sweeps across Infrapatella plica Tibia condyle. May cause Fibula pain and condylar erosion Lateral Subluxation and dislocation of patella Medial retinaculum/medial retinaculum patellofemoral ligament torn Medial Medial retinaculum retinaculum stretched Skyline view. Normally, patella rides In subluxation, patella deviates laterally; can be In dislocation, patella in groove between medial and lateral due to weakness of vastus medialis muscle, displaced completely out femoral condyles tightness of lateral retinaculum, and high Q angle of intercondylar groove DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT • Subluxation or disloca- ANTERIOR KNEE PAIN • Acute: MPFL repair tion of patella (lateral #1) • Recurrent/chronic: Patellar Instability • Associated w/anatomic physical therapy, brace; variants Hx: Pain & patella instability XR: 3 or 4 views: eval. patellar realignment PE: ϩ patellar apprehension, for fx and patella posi- surgery • MPFL is key structure ϩ/Ϫ increased Q angle, tion (lateral and/or pa- genu valgum, femoral an- tella alta) • NSAIDs, stretch and • Seen in jumpers (e.g., teversion MR: eval. MPFL if acute strengthen quadriceps basketball/volleyball and hamstrings players) Patellar Tendinitis • Surgical debridement • Microtears at tendon in- Hx: Sports, anterior knee XR: AP/lateral: normal (rare) sertion at distal pole pain (worse with activity) MR: Increased signal at PE: Patellar inferior pole TTP insertion (inferior pole) • Ice, NSAIDs • Fold in synovium (embry- or intrasubstance • Activity modification onic remnant) becomes • Arthroscopic debridement thickened or inflamed Plica (if symptoms persist) • Medial plica #1 Hx: Anteromedial pain, ϩ/Ϫ XR: Knee series. Eval. for popping/catching other pain sources • Inflammatory: ice, NSAIDs, • Etiology: trauma or over- PE: Tender, palpable plica, MR: Of questionable knee pads, rest, ϩ/Ϫ use (e.g., prolonged ϩ/Ϫ snap with flexion value aspiration; bursectomy if kneeling) persistent Prepatellar Bursitis • ”Housemaid’s knee” • Septic: bursectomy, abx • Inflammatory or septic Hx: Knee pain & swelling XR: Knee series: usu. PE: Egg-shaped swelling on normal anterior patella, TTP, ϩ/Ϫ LAB: CBC, ESR, ϩ/Ϫ as- signs of infection pirate: gram stain & cell count NETTER’S CONCISE ORTHOPAEDIC ANATOMY 325

9 Leg/Knee • DISORDERS Rupture of Anterior Cruciate Ligament Posterior cruciate ligament Anterior cruciate ligament (ruptured) Arthroscopic view Terrible Triad Rupture of medial collateral and anterior cruciate ligaments plus tear of medial meniscus DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT LIGAMENT INJURIES Anterior Cruciate • Mechanism: twisting injury, Hx: Twisting injury, XR: Knee series (Segond fx Based on functional stability often noncontact pivoting “pop,” swelling, inabil- is pathognomic for ACL) ‫ ؠ‬Stable/low demand pt: ity to continue playing MR: Absent/detached ACL, activity modification, PT, • Associated with other inju- PE: Effusion (hemarthro- ϩ/Ϫ bone bruise (middle brace ries: meniscal tears, collat- sis) ϩ Lachman (most LFC–posterior lateral tibia ‫ ؠ‬Unstable/athletes/active eral ligament (all 3 ϭ ter- sensitive), ϩ anterior plateau) pt: surgical reconstruc- rible triad) drawer, ϩ pivot shift Arthrocentesis: Hemar- tion (grafts: BTB, ham- throsis string, allograft ) • Common in female ath- letes COMPLICATIONS: arthrofibrosis, failure/recurrence (1. technical error, 2. missed ligamentous injury, 3. recurrent trauma) Posterolateral Corner • Mechanism: direct blow or Hx: Trauma, pain, insta- XR: Knee series. Avulsions • Nonoperative: low grade hyperextension/varus injury bility can occur (fibular head). (grades 1& 2 injury): PE: ϩ/Ϫ effusion, ϩ Alignment: eval. for varus brace & physical therapy • LCL, popliteus, popliteofib- prone ER test at 30°, MR: To evaluate all liga- ular ligament are injured. ϩ/Ϫ posterolateral ments and other soft • Surgical repair: acute These are focus of surgical drawer & ER recurva- tissues grade 3 reconstruction. tum tests • Surgical reconstruction: • Can be associated w/PCL chronic or combined in- injury jury, HTO if varus 326 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Leg/Knee 9 Rupture of posterior cruciate ligament Demonstration of hyperextension Posterior sag sign. Leg drops backward Collateral ligament injury 1st-degree sprain. Localized 2nd-degree sprain. Detectable 3rd-degree sprain. Complete joint pain and tenderness but joint laxity with good end point disruption of ligaments no joint laxity plus localized pain and tenderness and gross joint instability DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT • Mechanism: anterior LIGAMENT INJURIES • Nonoperative: isolated force on tibia (e.g., dash- (esp. grades 1& 2 injury): board injury) or sports Posterior Cruciate brace & PT (hyperextension) Hx: Trauma (dashboard) or XR: Knee series. Look for • Surgical reconstruction: • Associated with collateral sports injury, pain avulsion fracture. failed nonop treatment, and/or PL corner injuries PE: ϩ/Ϫ effusion, ϩ poste- MR: Confirms diagnosis. combined injury, some rior drawer, quadriceps Evaluates meniscus and isolated grade 3’s • Mechanism: valgus force active test, & posterior articular cartilage. • Common in football sag • Hinged knee brace • Usually injured at femoral • Physical therapy: ROM Medial Collateral origin (medial epicondyle) and strengthening Hx: Trauma, pain, instability XR: Knee series. Medial • Surgery: uncommon • Mechanism: varus force PE: Tenderness at medial epicondyle avulsion • Isolated injuries are rare, epicondyle along tendon. can occur (calcified ϭ • Isolated injury: hinged Pain/laxity w/valgus stress Pelligrini-Steida). brace usually combined with MR: Confirms diagnosis posterolateral corner (PLC) • Combined injury: surgical Lateral Collateral repair or reconstruction Hx: Trauma, pain, instability XR: Knee series. Fibular PE: Lateral tenderness. head avulsions can occur. Pain/laxity w/varus stress MR: Confirms diagnosis NETTER’S CONCISE ORTHOPAEDIC ANATOMY 327

9 Leg/Knee • DISORDERS Tears of meniscus Anterior Femoral cruciate condyle ligament May progress to Longitudinal (vertical) tear Bucket handle tear Bucket handle Arthroscopic view of bucket handle tear shows handle displaced into intercondylar fossa May progress to Radial tear Parrot beak tear Arthroscopic view of parrot beak tear Osteochondral defect with fibrillation of meniscal margin Stage 2 lesion Fragment of cartilage and bone Tunnel view radiographs of small OCD Arthroscopic view of knee lesion involving medial femoral condyle with osteochondral defect DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT • Acute: young, twisting injury INTRAARTICULAR CONDITIONS • Small/minimally symptom- • Degenerative: older ϩ/Ϫ OA atic: treat conservatively • Multiple tear patterns Meniscus Tear • Associated w/other injuries • Peripheral tears (red Hx: Pain & swelling XR: Knee series: usually zone): repair (heal best (ACL rupture, OCD, etc) esp. with flexion ac- normal. Early OA w/ACL reconstruction) • MedialϾlateral 3:1 (poste- tivities, ϩ/Ϫ catching often seen in pts or locking (e.g., w/degenerative tears • Central tears (white zone): rior horn most common) bucket handle tear) MR: Very sensitive for partial meniscectomy PE: Effusion, joint line tears. “Double PCL” sign • Spectrum: purely chondral tenderness, ϩ for displaced bucket han- Displaced OCD: internal to osteochondral lesions McMurray/Apley tests dle tears fixation Chondral: • Traumatic or degenerative Osteochondral Defect ‫ ؠ‬Debridement • Osteochondritis dissecans is ‫ ؠ‬Microfracture Hx: Often young/active XR: Knee series: 4 views ‫ ؠ‬Osteochondral transfer separate but similar entity pts. Pain (usually (need 45° PA & notch ‫ ؠ‬Chondrocyte implantation w/WB), ϩ/Ϫ popping, views), consider align- catching ment series PE: Inconsistent: ϩ/Ϫ MR: Good modality for effusion, bony ten- purely chondral lesions derness 328 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

DISORDERS • Leg/Knee 9 Quadriceps tendon rupture Rupture of quadriceps femoris tendon at superior margin of patella Torn retinaculum closed with interrupted sutures Patellar tendon rupture Rupture of patellar ligament at inferior margin of patella Ruptured patellar ligament repaired with nonabsorbable sutures through drill holes in patella; torn edges of retinaculum approximated with interrupted sutures DESCRIPTION Hx & PE WORKUP/FINDINGS TREATMENT OTHER Quadriceps Tendon Rupture • Mechanism: eccentric Hx: Older, fall/trauma XR: Knee series. Look for • Acute: primary surgical contraction or indirect PE: Effusion, palpable de- patella baja repair trauma fect above patella. Inabil- MR: Will show tendon tear. ity to do or maintain Usually not needed. May • Chronic: surgical recon- • Patients usually Ͼ40y.o. straight leg raise be helpful in partial tears. struction (tendon length- • Usually at musculotendi- ening or allograft proce- dure) nous junction Patellar Tendon Rupture • Mechanism: direct or in- Hx: Younger pts, trauma, XR: Knee series. Look for • Acute: primary surgical direct (eccentric load) pain, loss of knee patella alta repair trauma extension MR: Will show tendon tear. PE: Effusion, palpable de- Usually not needed. May • Chronic: surgical recon- • Patients usually Ͻ40y.o. fect in tendon. Cannot do be helpful in partial tears. struction (tendon length- • Associated with underly- straight leg raise ening or allograft proce- dure) ing tendon and/or meta- bolic disorder Tumor #1 in adolescents: osteosarcoma; #1 in adults: chondrosarcoma; #1 benign (young adults): giant cell tumor NETTER’S CONCISE ORTHOPAEDIC ANATOMY 329

9 Leg/Knee • DISORDERS TOTAL KNEE ARTHROPLASTY General Information • Goals: 1. Clinical: alleviate pain, maintain personal independence, allow performance of activities of daily living (ADLs) & recreation; 2. Surgical: restore mechanical alignment, restore joint line, balance soft tissues (e.g., collateral ligs.) • Common procedure with high satisfaction rates for primary procedure. Revisions are also becoming more common. Advances in techniques and materials are improving implant survival; this procedure now available to younger pts. Materials and Designs Materials • Femur component: cobalt-chrome commonly used for femoral-bearing surface with titanium stem • Tibia component/tray: does not articulate with femoral component. Often made of titanium. • Tibial tray insert: articulates with femoral component; made of polyethylene (UHMWPE, ultra high molecular weight PE) ‫ ؠ‬Polyethylene (PE) wears well but does produce microscopic particles that may lead to implant loosening & failure. ‫ ؠ‬Polyethylene should be at least 8mm thick, cross-linked for better wear, & sterilized in inert (non-O2) environment. ‫ ؠ‬Congruent design (not flat) improves wear rate and rollback (increased knee flexion). ‫ ؠ‬Direct compression molding is preferred manufacturing technique. • Cement: methylmethacrylate Prosthetic Designs • Unconstrained: 2 types. These are most common for primary surgical procedures with minimal deformity. ‫ ؠ‬Posterior cruciate (PCL) retaining (“CR”): preserves femoral rollback for incr. knee flexion but has incr. PE wear. ‫ ؠ‬Posterior cruciate (PCL) substituting (“posterior stabilized”) (“PS”): provides mechanical rollback, but may dislocate. Indicated for patellectomy, inflammatory arthritis, incompetent PCL (e.g., previous PCL rupture, etc). • Constrained (non-“hinged”): Used for moderate ligament (MCL/LCL) deficiency. Uses a central post to provide stability. • Constrained (“hinged”): Used for global ligament deficiency. Has high wear and failure rates. • Other: Mobile-bearing designs are available. Fixation • Cement. Most common. • Biologic. Bone ingrowth techniques. Theoretically have longer life, but have higher failure rates. Indications • Arthritis of knee ‫ ؠ‬Common etiologies: osteoarthritis (idiopathic, posttraumatic), rheumatoid arthritis, osteonecrosis ‫ ؠ‬Clinical symptoms: knee pain, worse with activity, gradually worsening over time, decreased ambulatory capacity. ‫ ؠ‬Radiographic findings: appropriate radiographic evidence of knee arthritis OSTEOARTHRITIS RHEUMATOID ARTHRITIS 1. Joint space narrowing 1. Joint space narrowing 2. Sclerosis 2. Periarticular osteoporosis 3. Subchondral cysts 3. Joint erosions 4. Osteophyte formation 4. Ankylosis • Failed conservative treatment: NSAIDs, activity modification, weight loss, physical therapy, orthosis (e.g., medial off- loader brace), ambulatory aid (e.g., cane in contralateral hand), injections (corticosteroid, viscosupplementation) Contraindications • Absolute: Neuropathic joint, infection, extensor mechanism dysfunction, medically unstable patient (e.g., severe car- diopulmonary disease). Patient may not survive the procedure. • Relative: Young, active patients. These patients can wear out the prostheses many times in their lives. Alternatives • Considerations: age, activity level, overall medical health • Osteotomy: relatively young patients with unicompartmental disease ‫ ؠ‬Valgus knee/lateral compartment DJD: distal femoral varus–producing osteotomy ‫ ؠ‬Varus knee/medial compartment DJD: proximal tibia valgus–producing osteotomy • Unicompartmental arthroplasty: unicompartmental disease • Arthrodesis/fusion: young laborers with isolated unilateral disease (e.g., normal spine, hip, ankle) 330 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

All components DISORDERS • Leg/Knee 9 in place Knee extended TOTAL KNEE ARTHROPLASTY Procedure Approaches • Midline incision with medial parapatellar arthrotomy is most common. • Minimally invasive incisions are also being used. Special equipment is often needed for the smaller incisions. Steps • Bone cuts ‫ ؠ‬Cut femur and tibia perpendicular to mechanical axis. Can use intramedullary (femur/tibia) or extramedullary (tibia) reference; this will restore the mechanical alignment ‫ ؠ‬Bone removed from femur and tibia should be equal to that replaced by the implants to maintain/restore joint line. • Implants—trial implants are first inserted to test adequacy of the bone cuts ‫ ؠ‬Implants should be best fit possible to native bone ‫ ؠ‬Femur placed in 3º of external rotation to accommodate a perpendicular bone cut of the proximal tibia (typically in 3º of varus) ‫ ؠ‬Femoral axis determined in 3 ways: 1. epicondylar axis, 2. posterior condylar axis, 3. AP axis—perpendicular to trochlea • Balancing ‫ ؠ‬Sagittal plane: goal is to make flexion & extension gaps equal. May need to cut more bone or add implant augments. ‫ ؠ‬Coronal plane: soft tissues are of primary concern. Rule is to release the concave side of the deformity. ‫ ؠ‬Varus deformity: release medial side: 1. deep MCL, 2. postmed capsule/semimemb insertion, 3.superficial MCL ‫ ؠ‬Valgus deformity: release lateral side: 1. lateral capsule, 2a. ITB (tight in ext.), 2b. popliteus (tight in flexion), 3. LCL ‫ ؠ‬Polyethylene trial: the knee should be stable and well balanced with the trial polyethylene in place. • Final implantation of components Complications • Patellofemoral complications are most common: patella maltracking, patellofemoral pain, patellar fracture. • Arthrofibrosis: may respond early (<6 wk) to manipulation under anesthesia. • Extensor mechanism failure: patellar tendon rupture or avulsion (difficult to repair/reconstruct); patellar fracture • Infection: diagnose with labs and aspiration. Prevention is mainstay: perioperative antibiotics, meticulous prep/drape technique, etc. Treatment: acute/subacute: irrigation & debridement with PE exchange. Late: 1- or 2-stage revision • Loosening: more common with biologic fixation. Also caused by microscopic particles from polyethylene wear • Neurovascular injury ‫ ؠ‬Peroneal nerve: esp. after mechanical axis correction of a valgus knee (nerve is stretched) ‫ ؠ‬Superolateral geniculate artery: should be identified and cauterized • Medical complications: Deep venous thrombosis (DVT) and pulmonary embolus (PE) are known risks of TKA. Prophylaxis must be initiated. • Periprosthetic fracture ‫ ؠ‬Femur: stable implant—nail or fixed angle device; unstable implant—replace with longer stem that passes fx site NETTER’S CONCISE ORTHOPAEDIC ANATOMY 331

9 Leg/Knee • PEDIATRIC DISORDERS Genu varum and valgum (bow leg and knock-knee) Two brothers, younger (left) with bowleg, older (right) with knock-knee. In both children, limbs eventually became normally aligned without corrective treatment Infantile tibia vara (Blount’s disease) Unilateral Bilateral DESCRIPTION EVALUATION TREATMENT • Normal (physiologic): ages 0-2 GENU VARUM • Physiologic: observation • Pathologic: Blount’s disease: • Infantile: Ͻ3y.o.: brace; Ͼ3y.o.: Hx: Parents notice a deformity 2 types PE: Unilateral or bilateral genu varum osteotomy ‫ ؠ‬Infantile: Ͻ3y.o., obesity, early XR: Tibia metadiaphyseal angle • Adolescent: hemiepiphysiodesis (TMDA): Ͻ9° is normal, Ͼ16° is walking pathologic/Blount’s (open physis) or osteotomy (closed ‫ ؠ‬Adolescent: insidious onset physis) GENU VALGUM Ͼ8y.o. • Physiologic: observation Hx: Parents notice a deformity • Pathologic: hemiepiphysiodesis • Normal (physiologic): ages 2-5 PE: Unilateral or bilateral genu valgum • Pathologic: skeletal tumors XR: Alignment x-rays: valgus is 6° in or osteotomy normal adults ‫ ؠ‬Metabolic: renal osteodystrophy ‫ ؠ‬Other: trauma, infection 332 NETTER’S CONCISE ORTHOPAEDIC ANATOMY

PEDIATRIC DISORDERS • Leg/Knee 9 Posteromedial bowing of tibia Posteromedial bowing. Convexity of bow in distal third of tibia and fibula directed posteriorly and medially. Spontaneous correction usually obviates need for realignment osteotomy, but leg-length discrepancy often persistent. Anterolateral bowing of tibia and congenital pseudarthrosis Congenital pseudoarthrosis of the tibia. Angulation of right leg. Café au lait spots on thigh and abdomen suggest relationship to neurofibromatosis. Anterolateral bowing. In infancy it may be difficult to predict if anterolateral bowing will correct spontaneously or if bone will progress to fracture and congenital pseudarthrosis. Progression to pseudarthrosis is more likely if the medullary canal is narrow and has sclerotic changes. Anterolateral bowing. Medullary canal present but narrow with sclerotic changes; cyst apparent. Prone to spontaneous fracture and pseudarthrosis DESCRIPTION EVALUATION TREATMENT TIBIA BOWING Posteromedial Bowing • Congenital convexity of tibia Hx: Deformity present at birth • Bowing resolves with growth • Idiopathic, unilateral PE: Foot appears dorsiflexed (calca- • Deformity corrects but a leg length neovalgus), leg is bowed • Resultant leg length discrepancy XR: Bowing of tibia and fibula ‫ ؠ‬Mild: shoe lift discrepancy usually results ‫ ؠ‬Severe: hemiepiphysiodesis Anterolateral Bowing/Congenital Tibia Pseudarthrosis • Bowing of tibia, unknown etiology Hx/PE: Leg deformity & disability. • Young/bowing tibia: full contact brace • Associated with neurofibromatosis Bowed leg, ϩրϪ signs of neurofi- • Pseudarthrosis: tibial nail/external • Anterolateral bowing can lead to bromatosis (e.g., café au lait spots) XR: Reveals bowing or pseudarthrosis fixation & bone graft pseudarthrosis • Amputation: if surgical treatment fails NETTER’S CONCISE ORTHOPAEDIC ANATOMY 333