CHAPTER 10 Ankle and Foot EPIDEMIOLOGY OF ANKLE AND FOOT PAIN FOOT AND ANKLE PAIN IN THE GENERAL POPULATION (1) Prevalence • 20% to 42% in people >65 years (2) • Significant foot pain is more common in obese females and older people (especially individuals 65–74 years old [YO]) Risk factors • Relationship between shoes and foot pain • Foot pain can be related to poor functional performance, walking, stair negotiation, and history of multiple falls FOOT AND ANKLE PAIN IN ATHLETES (4) Prevalence • Ankle: most commonly (MC) injured joint among athletes (up to 30%); ankle sprain (75%–85%) (5) • Common in soccer, basketball (>40%), football (>10%, lateral sprain: MC), long-distance runners (overuse), young dancers, and gymnasts (fracture and fatigue fracture) Adolescent athletes • Growth-related problems (coalitions and accessory ossicles), overuse injuries (apophysitis and osteochondrosis), stress fractures, and epiphyseal fractures FOOT AND ANKLE PAIN AT WORK (6) Prevalence • 10% of total workplace injury, median of 5 days off Common causes • Direct trauma, secondary to slip, trip/fall, or shoe-related problem • Related to environment (construction zone, type of floor, etc), type of footwear, long periods of standing • Ankle: sprains and strains: MC (>70%) followed by fractures (15%) and bruises (contusion, 5%) • Foot: bruises > fractures > sprains and strains > cuts and punctures • Toes: fractures > bruises DIFFERENTIAL DIAGNOSIS MUSCULOSKELETAL (MSK) CAUSES OF FOOT AND ANKLE PAIN BASED ON LOCATION (FLOWCHART 10.1) Classification of foot regions (Figure 10.1) • Forefoot: metatarsal (MT) and phalanges FIGURE 10.1 Surface anatomy of the foot and ankle. Source: Courtesy of Dr. Mooyeon Oh Park. • Midfoot: cuneiform, cuboid, tarsometatarsal (TMT) (Lisfranc) joint, and cuneiform-navicular joint • Hindfoot: talus, calcaneus, subtalar, and midtarsal joint (Chopart joint: talonavicular and calcaneocuboid joints) (7) • Ankle joint: tibiotalar joint and tibiofibular syndesmosis Foot pain FLOWCHART 10.1 Classification of foot and ankle pain. MSK, musculoskeletal; post., posterior. DIFFERENTIAL DIAGNOSIS OF MSK HINDFOOT AND ANKLE PAIN REGION ANATOMIC STRUCTURE PATHOLOGIES Plantar heel Fat pad Fat-pad atrophy: middle age, rare in young adult ± H/O steroid injection Plantar fascia Plantar fasciitis: MC cause of plantar heel pain. Pain at the fascial insertion to medial calcaneal tuberosity Plantar fibromatosis: distal to the insertion, palpable nodule Calcaneus Stress fracture: vague pain, H/O osteoporosis, diabetes mellitus (DM), or recent change in activity Peroneus longus tendon Tendinopathy/tear: Lateral plantar heel to medial midfoot, deep, ± H/O inversion sprain Posterior heel/ankle Achilles tendon Non-insertional tendinopathy/tear: MC cause of the posterior heel pain (4 times more than insertional) Insertional Achilles tendinopathy (2nd MC) Os trigonum Os trigonum syndrome: deep posterolateral pain ± H/O minor ankle trauma or repetitive trauma Flexor hallucis longus tendon Tendinopathy/tenosynovitis: posterior medial ankle/hindfoot pain, ± H/O ankle sprain or overuse (ballet) Bursa Retrocalcaneal/superficial calcaneal bursitis: often irritated from shoe (heel counter) ± bulging. Patient prefers open back shoes (clogs, slippers, flip flops) Joint Posterior ankle/subtalar joint effusion/synovitis or loose body. Worsening pain on tip toe walking Dorsum and ankle Tibiofibular lig. (syndesmosis) High ankle sprain: persistent pain after sprain (eversion and dorsiflexion) ± instability Soft tissue Anterolateral impingement syndrome: gradual onset of pain after injury Pain on ankle dorsiflexion (late stance phase of gait) Talar dome Osteochondritis dissecans: chronic pain after ankle sprain. Pain is typically not localized Midtarsal joint Talonavicular and calcaneocuboid joint/ligament sprain or arthritis Medial ankle/hindfoot Tibialis posterior (TP) tendon Tendinopathy, tear, and tenosynovitis • Pain between medial malleolus and navicular tuberosity, acquired pes planus Deltoid ligament H/O eversion sprain, significant pain, often difficult weight bearing initially, and ecchymosis Talonavicular joint Arthritis: tarsal coalition or foot alignment issues (pes planus, cavus) Lateral ankle/hindfoot Lateral ligament Sprain: MC cause of ankle pain (especially, anterior talofibular ligament) • Common with pes cavus (hindfoot inversion), and H/O previous injury Peroneal tendon Tendinopathy, tear (brevis: more common), tenosynovitis, and subluxation • Pain on the behind/distal to the lateral malleolus (posterolateral) ± intermittent snapping, usually after inversion injury Sinus tarsi Sinus-tarsi syndrome: common cause of persistent pain after ankle sprain Calcaneocubiod joint Arthritis Sprain common in dancing, underrecognized cause of sinus-tarsi pain DM, diabetes mellitus; H/O, history of; lig., ligament; MC, most common; TP, tibialis posterior. DIFFERENTIAL DIAGNOSIS OF MSK MIDFOOT PAIN REGION ANATOMIC STRUCTURE PATHOLOGIES Lateral Cuboid-4th metatarsal bone Arthritis, subluxation (cuboid subluxation, often reduced by the patient), and sprain Os peroneum Painful Os peroneal syndrome Medial Navicular Kohler disease (navicular osteochondrosis) or Müller–Weiss syndrome (navicular osteonecrosis) Painful accessory navicular syndrome Naviculocuneiform arthritis Often associated with 1st ray insufficiency (hypermobile 1st ray) FHL or FDL (at master knot of Henry) Tendinopathy or tethering • Rare cause of medial arch pain FDL, flexor digitorum longus; FHL, flexor hallucis longus. DIFFERENTIAL DIAGNOSIS OF MSK FOREFOOT PAIN REGION ANATOMIC STRUCTURE PATHOLOGIES 1st ray 1st metatarsophalangeal (MTP) joint Gout: MC cause of acute disabling foot pain, 1st MTP joint; MC location for gout Hallux rigidus/limitus: pain on the dorsum of 1st MTP joint initially Hallux valgus with bursitis: pain on the medial side Sesamoid Sesamoiditis, sesamoid fracture/necrosis: plantar aspect of the MTP joint 2nd ray 2nd MTP joint Subluxation or dislocation. Pain can be worsened by tight shoe ± crossing over/overlying toes 2nd metatarsal bone Stress fracture Change in amount of weight-bearing activity; common in athletes (with nutritional imbalance), and osteoporosis Freiberg disease (osteonecrosis of 2nd metatarsal head): adolescent female Lesser toes Bursa Intermetatarsal bursitis ± irritation of interdigital N Taylor’s bunion (Bunionette deformity) on the lateral side of 5th metatarsal head MTP joints and soft tissues MTP joint arthritis/synovitis (highly involved in inflammatory arthropathy; underrecognized) Lateral overloading syndrome: often H/O medial arch support (excessive) MC, most common; MTP, metatarsophalangeal; N, nerve. NEUROPATHIC CAUSES OF FOOT AND ANKLE PAIN BASED ON LOCATION (FLOWCHART 10.2) FLOWCHART 10.2 Differential diagnosis of neuropathic causes of foot and ankle pain. Ant., anterior; LS, lumbosacral; N, neuropathy. REGION DIFFERENTIAL DIAGNOSES NOTES Heel Baxter’s (inferior calcaneal N) entrapment neuropathy Deep, aching (because of periosteum innervation), and tingling Underrecognized cause of chronic recalcitrant heel pain. Aggravated by hindfoot valgus Medial calcaneal entrapment neuropathy A rare cause of burning, pins/needles pain in the heel Dorsal Superficial peroneal neuropathy Worse at night (weight of blanket plantarflex the ankle with stretching of superficial peroneal nerve) and aggravated by tight shoe H/O inversion ankle sprain Deep peroneal neuropathy Underrecognized cause of sinus-tarsi pain by compression of the lateral branch of deep peroneal N to extensor digitorum brevis Sole Tarsal tunnel syndrome Neuropathic pain on the sole of the foot, often aggravated by hindfoot eversion, pronation Distal tarsal tunnel syndrome: involving a branch similar to presentation of isolated inferior calcaneal, medial calcaneal, or medial plantar neuropathy Peripheral neuropathy Large fiber-mediated symptoms (unsteadiness) and small fiber symptoms (burning, pins/needles sensation), symmetric. Medial Medial plantar N (jogger’s foot) Medial arch pain with radiating pain distally and proximally Hallucal neuropathy Numbness, tingling, pins/needles pain in the big toe with pain radiation proximally (Valleix’s phenomenon) Lateral forefoot Interdigital neuritis Pain radiating distally but occasionally radiating proximally, with numbness Regional or Diffuse Peripheral neuropathy/small fiber neuropathy, or erythromelalgia Complex regional pain syndrome: often focal neuropathy misinterpreted as generalized pain Herpes neuralgia; can precede the skin lesions N, nerve; H/O, history of. OTHER CAUSES OF SEVERE (DISABLING) FOOT PAIN • Compartment syndrome: history of trauma or injury • Acute ischemia: with history of vascular disease, rest pain, pain relieved by dependent position • Drug-seeking behavior COMMON CAUSES OF PES CAVUS (HIGH ARCH FOOT) CATEGORIES CAUSES Neuromuscular (progressive) Muscle disease Muscular dystrophy Peripheral nerves and root Charcot-Marie-Tooth disease/peripheral neuropathy (common) Anterior horn cell Dx Polio, spinal dysraphism (can involve root only), diastematomyelia, syringomyelia, spinal cord tumor, spinal muscular atrophy Long tract and central nervous Dx Cerebral palsy, Friedreich’s ataxia, Roussy-Lévy syn., primary cerebellar disorder Congenital (lifelong) Idiopathic, residual of clubfoot (equinocavovarus), arthrogryposis, and fibular hemimelia Traumatic Residuals of compartment syndrome, crush inj. to lower ext. severe burn, malunion of foot Fx. Talar neck fracture Dx, diagnosis; ext., extreme; Fx, fracture; inj., injury; syn., syndrome. DIFFERENTIAL DIAGNOSIS OF PES PLANUS (FLAT FOOT, NORMAL UP TO 6 YEARS) CATEGORIES CAUSES Congenital Congenital vertical talus: congenital rigid flat foot • Associated with neuromuscular disease (arthrogryposis, meningocele) Tarsal coalition: severe osteophyte in the talonavicular joint (common) Muscle weakness TP dysfunction (insufficiency): MC cause of acquired flat foot Ligament laxity Hypermobile flat foot Hyperpronated foot Dropping of the talar head ± spring ligament injury/insufficiency Femoral int. rotation, coxa vara, and medial tibial torsion Trauma and others Calcaneal fracture Charcot neuroarthropathy (long-standing DM: MC cause) DM, diabetes mellitus; MC, most common, TP, tibialis posterior. DIFFERENTIAL DIAGNOSIS OF ANKLE EQUINUS Muscular • Normal aging, immobility, upper motor neuron syndrome, deconditioning, DM, Achilles enthesopathy/tendinopathy/tear, and the like Osseous (pseudoequinus): anterior tibiotalar exostosis, distal tibiofibular osseous bridging DIFFERENTIAL DIAGNOSIS OF ANKLE INSTABILITY Recurrent ankle sprain (MC cause), occurs in 10% to 30% of recurrent ankle sprain Mechanical causes: arthrokinetic restriction, synovial, and degenerative pathologies • Loose bodies, osteochondral injuries, chondromalacia, osteophytes/painful ossicles, synovitis/adhesion, impingement, and peroneal tendon pathology Functional causes: proprioception, neuromuscular, impaired postural control, and strength deficit DIFFERENTIAL DIAGNOSIS OF SNAPPING ANKLE (8) Lateral (behind the lateral malleolus, MC) • Peroneal tendon subluxation with retinacular injury, more common than extensor digitorum longus (EDL) with inferior retinaculum injury Medial • TP subluxation and dislocation or tibialis anterior (TA) snapping LATERALIZATION OF PAIN Pain on the lateral forefoot, midfoot, hindfoot, and lateral calf due to compensatory mechanism (avoid weight bearing on the medial side) Common underlying medial foot pathologies • Hallux rigidus/limitus (with/without gout or degenerative joint disease (DJD) of MTP joint) • 1st ray insufficiency (with medial cuneiform-metatarsal joint arthropathy) • 2nd MTP joint arthralgia/subluxation • Plantar fasciitis • Posterior tibialis tendon dysfunction • Ambitious arch syndrome from medial arch support (or foot orthotics) DIFFERENTIAL DIAGNOSIS OF NEUROPATHIC ANKLE AND FOOT PAIN Length-dependent neuropathy: stocking pattern, distal symptoms more severe than proximal Focal/regional pain Plantar More than one part of foot (regional or diffuse) involved • Tarsal tunnel syndrome (proximal) • Distal peripheral neuropathy • Lumbosacral radiculopathy Medial • Distal tarsal tunnel syndrome involving the medial plantar nerve • Medial plantar neuropathy (jogger’s foot) • Medial hallucal nerve lesion (at MTP joint area) Lateral • Morton’s interdigital neuritis • Distal tarsal tunnel syndrome involving the lateral plantar nerve • Lateral plantar neuropathy; neurilemma, iatrogenic, etc Heel • Medial calcaneal nerve: posterior heel/cutaneous burning, pins/needles sensation • Baxter’s nerve (1st branch of the lateral plantar nerve); deep aching pain in the heel Dorsum Medial • Superficial peroneal neuropathy (where it perforates the crural fascia above the ankle, rarely at the level of the knee) • Anterior tarsal tunnel syndrome involving deep peroneal neuropathy • Hallux rigidus/limitus with dorsal osteophytes irritating the deep and superficial peroneal nerves/medial dorsal branch, or the medial dorsal hallucal nerve • Saphenous N lesion (at the knee or leg) • L5 radiculopathy Lateral • Deep peroneal N (branch to EDB, sinus-tarsi syndrome) • Superficial peroneal N (perforating the crural fascia or distally at navicular junction) • Sural neuralgia • S1 radiculopathy EDB, extensor digitorum brevis; N, nerve. ANATOMY BONE AND JOINT Ankle joint • Talus – Dorsiflexion – Plantarflexion • Ankle joint axis: medial 8° higher (lower in lateral side) in coronal plane, the lateral malleolus is 20° to 30° posterior compared to the medial malleolus (axial plane) • Ankle stabilizers: bony (mortise with wide anterior talar dome), ligaments, muscles across the ankle joint Subtalar joint (Figure 10.2) • Between talus and calcaneus with three articular facets: anterior, middle, and posterior facets • Triplanar mechanism (movement similar to 45° oblique hinge) • Stabilizers (9) Midtarsal joint (Chopart or transverse tarsal joint) • Calcaneocuboid and talonavicular joint FIGURE 10.2 Bony anatomy of foot with location of accessory bone (ossicles). – Bifurcate ligament (calcaneocuboid, calcaneonavicular) in the dorsum – Wedge-shaped labra within calcaneocuboid joint – Spring ligament (calcaneonavicular) in the medial/plantar aspect – Plantar calcaneocuboid ligament TMT joint: referred as midfoot joint or Lisfranc joint • Cuneiform-metatarsal and cuboid-metatarsal joints • Medial column (1st ray, medial cuneiform–1st metatarsal (MT)), middle (2nd and 3rd ray, intermediate, lateral cuneiform-metatarsal) and lateral column (cuboid-4th and 5th MT) • Stabilizers of TMT joint – Reduced range of motion (ROM) of the 1st MT during walking – Disproportionate increase in 1st MT and calcaneal eversion ROM – Stress fracture more common in 2nd metatarsal bone – Can be related to intractable plantar keratosis underneath • Cuneiform-metatarsal; less mobile versus cuboid-metatarsal; more mobile – Dorsal and plantar cuboideometatarsal ligaments – Wedge-shaped fibroadipose labra within cuboid metatarsal joints – 4th metatarsal cuboid sprain 1st MTP joint • Stabilizers (inherently unstable joint) LIGAMENT Ankle ligaments (10) • Lateral ankle ligaments: anterior/posterior talofibular, and calcaneofibular ligaments • Deltoid ligament – Holds calcaneus and navicular against the talus and reinforces the action of the spring ligament on which the head of the talus rests Syndesmosis • Anterior-inferior tibiofibular ligament (accessory ligament: Basset ligament), post-inferior tibiofibular ligament (the strongest), inferior transverse tibiofibular ligament (form a labrum/fibrocartilagenous), and interosseous tibiofibular ligament • Important ankle mortise stabilizer Spring ligament (11) • Composed of inferior (more rigid) and superomedial (more elastic, injured MC) calcaneonavicular ligament • Functions • Ligaments at TMT joint – Located between the medial cuneiform and the base of the second metatarsal – The largest of the interosseus ligaments and strongest in providing the most stability, followed by the plantar and dorsal ligaments, respectively RETINACULUM (14) Flexor retinaculum • Medial side, roof of tarsal tunnel Extensor retinaculum • Dorsum of the foot and ankle • Superior (above the ankle joint) and inferior (at ankle joint and tarsal bone) extensor retinaculum • Inferior extensor retinaculum º Inferior (inferomedial) band: roof of anterior tarsal tunnel (deep peroneal nerve entrapment site; anterior tarsal tunnel syndrome [TOS]) Peroneal retinaculum • Superior: sheath covering peroneal tendons in retromalleolar groove, can be injured during inversion injury causing instability or lateral ankle snapping • Inferior: from lateral rim of the sinus tarsi to a point of attachment below the trochlea of the calcaneus. If injured NERVE (16) Tibial nerve (main motor nerve to intrinsic foot muscles and sole of the foot), peroneal nerve (dorsum of foot and extensor digitorum brevis and peroneus tertius), saphenous nerve (medial), and sural nerve (lateral side of ankle and foot) Tibial nerve branches (17) (Figure 10.3) • Medial plantar nerve: 1st lumbrical, abductor halluces, and FHB; cutaneous sensation of medial plantar sole. Continues to be the medial hallucal nerve (with other nerve contribution) • Lateral plantar nerve: 4th interosseous; quadratus plantae, flexor digiti minimi brevis, adductor hallucis, 2nd to 4th lumbricals, and lateral plantar sole • Interdigital nerves: sensory branches from medial and lateral plantar nerves • Inferior calcaneal nerve (Baxter’s nerve, or 1st branch of lateral plantar nerve) Peroneal nerve (Figure 10.3) • Common peroneal nerve passing around the fibular neck in an exposed fibro-osseous tunnel bordered superficially by the peroneus longus tendon FIGURE 10.3 Nerve innervation of the foot and ankle. • Superficial peroneal nerve • Deep peroneal nerve • Anatomy of anterior tarsal tunnel Big-toe innervation • Medial hallucal nerve; extension of medial plantar nerve • Deep peroneal nerve (1st web space) • Superficial peroneal nerve (medial dorsal branch) • Saphenous nerve (controversial) MUSCLE BIOMECHANICS KINETIC AND KINEMATIC (18) Ankle joint: approximately 5 times the body weight (BW) loading during walking Ground reaction force (GRF) during stance phase: typical muscle pattern (first peak; initial heel strike, 2nd peak: heel rise and heel off), lower during midstance Compensation mechanism (19,20) • In a closed chain system (eg, standing or stance phase of gait), each segment is interrelated and interdependent (eg, pronation and supination response) • Loss of mobility at any one joint • Tight Achilles cord (gastrocnemius) increases loading on the forefoot • Rationale for orthotic or footwear: mitigating painful or abnormal degrees of compensation by accommodating loss of mobility in addition to decreasing painful ROM ANKLE AND FOOT IN GAIT (21) Ankle joint (19) • To advance in the mid- to terminal stance of gait, 10° dorsiflexion is ideally required – Can cause posterior knee pain or infrapatellar fat-pad impingement Subtalar joint • Subtalar eversion and tibial-talar internal rotation during initial heel strike Midfoot and forefoot • The weight-bearing cross-lateral oblique (toe break line: weight bearing, shorter lever) to medial oblique (mobile, longer lever from calcaneus to big toe) • Midfoot joint • Loss of dorsiflexion of the first metatarsal phalangeal joint (MTPJ); hallux limitus/rigidus Pronation and supination response PRONATION SUPINATION Forefoot Midfoot/hindfoot Forefoot abduction Midfoot dorsiflexion Talonavicular and calcaneocuboid joint are parallel Navicular dropping Talus: medially deviated, plantarflexed Calcaneal eversion (normal up to 5°–10°) Forefoot adduction Midfoot plantarflexion Talonavicular and calcaneocuboid joint intersect Calcaneal inversion Common foot pattern/deformity Flat foot (forefoot varus/hindfoot valgus) Cavus foot (forefoot valgus and hindfoot varus) Proximal segment Tibial/femur internal rotation (on standing; closed kinetic chain) Tibia/femur external rotation Common pathologies Posterior tibialis tendon insufficiency Navicular pain, calcaneocuboid joint pain Peroneus tendinopathy Midtarsal joint pain FOOT ALIGNMENT AND DEFORMITY (23) Arches of the foot º Beam (plantar ligament) and truss mechanism and windlass mechanism (plantar aponeurosis) • Transverse arch Neutrally aligned feet: lower frequencies of intrinsic muscle atrophy, bony prominences, and toe deformities Pes cavus (high arch foot) (26) • Selective muscle weakness – Unopposed pull of posterior tibialis tendon (with fascia of abductor hallucis shortened) and tight Achilles cord – Unopposed pull of peroneus longus (PL) (plantarflexion of 1st MT; forefoot supinatus) – Achilles cord; hindfoot adductor (varus), EHL recruited as secondary ankle dorsiflexor – Unopposed EDL: hyperextend the lesser MTP joint and flexion deformity of interphalangeal joint, forefoot equines • Foot pain and deformity related to pes cavus (27) Pes planus (flat foot) • Principal mechanical contributors: contracture of the triceps surae, attenuation of the ligamentous supports, and PTT dysfunction (25) • Common foot pain conditions related to pes planus (28) PHYSICAL EXAMINATION INSPECTION (29) Medial longitudinal arch • From medial side inspection: look for congruence, flat in pes planus, and high arch (acute angle) in pes cavus Hindfoot and midfoot • Talonavicular joint area (observation from behind): concave (cavus) or convex (bulge: planus) • Lateral aspect: convex (bulge) in pes cavus and concave below the lateral malleolus in pes planus • Posterior aspect: calcaneus inversion (medial) in pes cavus and eversion in pes planus Forefoot • Alignment: abduction (lateral; too many toes sign) in pes planus or adduction in pes cavus (on axial plane) • Forefoot deformities: hallux valgus, varus, toes (claw, hammer toes similar principles to finger deformity), joint enlargement/osteophytes, gout, OA, hallux rigidus/limitus • Overlying toe, widening of 2nd web space, 2nd MTP subluxation (medially) • Too-many-toes sign (≥2 toes laterally, from observation from behind) observed in forefoot abduction (pes planus and with posterior tibialis dysfunction) Excessive callus • Metatarsal heads (at MTP joint) common with Achilles tightness and pes cavus (1st ray plantarflexion), callus under the lesser toes common with 1st ray insufficiency (with pinch callus in phalange) • Baby-like skin (indicating limited weight bearing) common with 1st ray insufficiency Inspection of shoes • Size; tight shoes (especially with forefoot pain), and worn-out pattern (laterally worn out in pes cavus, medially worn out in pes planus) Foot posture index for pes cavus and planus (29) • To semiquantify the degree of pronation or supination; useful in follow-up º Each component has −2 (supination) to +2 (pronation) • Inspection for other foot deformities: equinus, varus, equinovarus, equinovalgus, and calcaneovalgus • Have patient undress to evaluate the proximal segments • Calf for atrophy or pseudohypertrophy, knee and hip alignment, and back for spinal deformity PALPATION (SEE FIGURE 10.1) Medial side • Bony landmark • Tendon Lateral side • Lateral malleolus: ATFL attached at the tip • Peroneal tubercle: inferior (1–1.5 cm below) and slightly distal to the lateral malleolus; bony crest between peroneus longus (below) and brevis (above); prominent in males, pes cavus, and osteoma formation • Cuboid: groove for peroneus longus • 5th MT (styloid process); gives attachment to peroneus brevis Dorsum • Ankle joint: about 1 cm above the bisecting line of the medial and lateral malleolus • Talar head: bisecting line between the medial malleolus and navicular tuberosity, immediately proximal to the talonavicular joint prominent on eversion • Sinus tarsi: depression at distal/medial (perpendicular to the foot axis) to the lateral malleolus • TA (easily visible with slight inversion and dorsiflexion), extensor hallucis longus (lateral to TA), dorsalis pedis artery, and deep peroneal nerve (not palpable) laterally Plantar • Medial calcaneal tuberosity: attachment site of plantar fascia • Master knot of Henry: medial plantar nerve entrapment site at crossing of FHL and FDL (under the naviculocuneiform joint); difficult to palpate • Sesamoids (move with flexion/extension of big toe as these are embedded in FHB, differential with MTP joint in tenderness) RANGE OF MOTION Ankle joint motion • Place subtalar joint in neutral, move the calcaneus and measure the angle between fibular shaft and lateral aspect of the sole • Subtalar neutral with congruent talonavicular or calcaneocuboid joint: removes subtalar/midtarsal joint compensation. Compensation usually occurs with over-pronation response with navicular lateral deviation or drop • Silfverskiold test: check ankle dorsiflexion (for Achilles cord tightness) while extending flexed knee (differentiate gastrocnemius component from soleus) • Equinus: inability to dorsiflex the ankle ≥10° (31) Subtalar joint motion • Subtalar motion: 25° inversion/supination and 10° of eversion/pronation (2:1 ratio of inversion to eversion) • Subtalar neutral: anatomical neutral position for physical examination • With patient in a prone position, the bisected line of the heel is compared with the bisected line of the lower leg while the calcaneus is being inverted and everted Check the forefoot (MTP joint) sitting and standing (MTP dorsiflexion with tethering effect from tight FHL) Check for hypermobility: Beighton scale ≥4/9 (1 point for each side; 5th MCP hyperextension >90°, passive apposition of the thumb to forearm, elbow hyperextension >10°, knee hyperextension >10°, and trunk forward flexion to place the palm of the hand at rest on the floor; see Figure 1.2) • Benign joint hypermobility syndrome; major criteria: SPECIAL TESTS (see following table) NAME DESCRIPTION SENSITIVITY (SEN) AND SPECIFICITY (SPE) IN % Ankle Sprain Inversion/eversion stress test (talar tilt test) With ankle plantarflexion at 20º and knee flexion at 90º, heel is held from below by one hand while the other hand holds the lower leg Push the calcaneus and talus into eversion while the other hand grips the lower leg laterally and pushes medially for deltoid ligament injury and the opposite (inversion for anterior talofibular and calcaneofibular lig. injury) Positive if pain and laxity found during maneuver Sen: 71–96, Spe: 33–84 (within 48 hours), higher in 4–7 days (33) Anterior drawer test Examiner stabilizes the distal tibia with one hand, while grasping the heel with the other hand. Apply an anteriorly directed force to the heel. This test should be performed bilaterally to compare for differences in anterior translation Positive if pain or increased joint laxity ± a dimple or if >3 mm translation Limited in patients with ligament laxity or guarding with pain Sen: 80, Spe: 74 Anterolateral drawer test Isolated testing of ATFL. Anterior drawer test with slight medial rotation of the forefoot. Slight medial rotation isolates resistance of anterior translation by tibionavicular lig. With ankle plantarflexed, it can isolate CFL Syndesmosis Injury Squeeze test With proximal calf squeeze (distract/widen the distal part), the patient reports pain in the ankle. Less reliable than passive ankle dorsiflexion test • Passive ankle dorsiflexion test; widen mortise (stretch the syndesmosis) as anterior talar dome is wider Cross leg test With crossing the symptomatic leg, the patient reports pain (in the ankle) and symptom reproduction • Weight of foot externally rotate the leg by gravity External rotation stress test Similar principle to cross leg test with widening the mortise by abducting forefoot Other Heel Examination Calcaneal squeeze test Mediolateral compression simultaneously by thenar eminence causing pain Positive in calcaneal fracture and Sever’s disease (apophysitis) • Heel propping test: stand with examiner holding the fat pad with hypothenar eminence Sen: 97, Spe: 100 for Sever’s disease Coleman’s block test To evaluate the midfoot flexibility of forefoot-driven (PL-driven) cavovarus Place wooden block (1 or 1/2 inch) under the lateral border of the foot (4th and 5th MT) to reverse forefoot supinatus (varus) • If hindfoot varus is supple, hindfoot varus correctable, Figure 10.4 • If hindfoot varus is fixed Tibialis Posterior (TP) Dysfunction Heel rise test Normally, the patient inverts the hindfoot as they lift heels, positive if failed to do on double heel rise test Single heel rise test if the double heel rise test is intact (36) Metatarsal rise test The patient stands, fully loading both feet. The shin of the affected side is taken with one hand and externally rotated. By doing this, the heel is passively brought into a varus position because of the mechanical coupling between the tibia and calcaneum (supination response). The head of the first metatarsal remains on the ground in normal function of the tendon but is lifted in dysfunction (37) Morton’s Interdigital Neuritis (38) Lateral squeeze test Squeeze the metatarsal shaft from the sides Often false positive if pressed on the MTP joint (pain source can be from MTP joint pathology) Mulder’s click Squeezing the forefoot (metatarsal shaft) from the sides. Positive (for neuroma) if a palpable (not necessarily audible) clicking is appreciated Compression test Compress the nerve from the plantar aspect (distal to the MTP joint) with MTP dorsiflexion (therefore, exposing the interdigital N plantarly). Positive if reproducing the symptom Pinch test Pinch from the plantar and dorsum of interdigital space. Positive if reproducing the symptom First Ray Insufficiency Drawer sign Shift 1st metatarsal head compared to the 2nd MT head. Positive if ≥8 to 10 mm of dorsal displacement occurs Achilles Tendon Rupture Matles test In the prone position, with the foot over the end of the table, the patient is asked to flex the knee to 90°. The position of the foot is observed throughout the arc, and the foot is slightly plantarflexed normally. Positive if the foot falls into neutral or the slightest dorsiflexed position Sen: 88, Spe: 85 Thompson test When squeezing the calf of the affected leg, normally the ankle will be slightly plantarflexed. Positive if no motion of the foot occurs Sen: 96, Spe: 93 ATFL, anterior talofibular ligament; CFL, calcaneofibular ligament; lig., ligament; N, nerve; Sen., sensitivity; Spe., specificity; TP, tibialis posterior. FIGURE 10.4 Coleman’s block test Evaluation for instability (39) • Ankle and subtalar instability; difficult to distinguish clinically (9) • Evaluate cavus deformity (hindfoot varus, 1st ray plantarflexion), generalized ligamentous laxity (Beighton score), hindfoot varus (inspection and Coleman block test), and ankle ligaments injury • Subtalar instability test: calcaneus inversion test with ankle dorsiflexion (stabilizing the ankle joint) • Midtarsal joint examination by abduction/adduction stress test
Rare in population not wearing shoes. More common in females wearing tighter shoes (3)
Static MRI: not sensitive 
better evaluated by dynamic ultrasound (US) with passive ankle dorsi/plantarflexion with eversion
Talar dome: wider anteriorly
Ankle dorsiflexion engages anterior part into the mortise 
fits more securely (stable) and can cause pain in syndesmosis injury (widen tibiofibular space)
Plantar flexion of ankle (narrower posterior dome) 
unstable (more common position in ankle sprain)
Axis of talus to the 1st web space (in relation to impingement)
Bony impingement
anteromedial impingement
Posterolateral impingement
If impingement location is at anterolateral or posteromedial of the ankle 
suspect soft tissue (ligament and scar tissue) impingement
Direct blood supply retrograde fashion in talus (because of limited soft-tissue attachments) 
vulnerable to osteonecrosis
Ankle dorsiflexion 
slight abduction of forefoot due to tilting
Ankle joint x-ray (mortise view): internally rotate the leg by 20°
Ankle dorsiflexion blocks (stabilizes) the movement in the ankle mortise, and tightens the Achilles tendon and locks the subtalar joint
Multiple configurations in joint articulations and orientations
Axis: 42° (posterior-inferior to anterior–superior in sagittal plane) and 16° (posterolateral to anteromedial in axial plane)
Pronation: dorsiflex in sagittal plane with forefoot abduction in axial plane and hindfoot eversion in coronal plane
Supination: the opposite of pronation when the foot responds to the demands of uneven terrain
Bony configuration of facets: anterior, middle, and posterior facets
Muscles across the subtalar joint
Ligamentous stabilizers
Major stabilizers: interosseous talocalcaneal ligament (most important), cervical ligament, and lateral talocalcaneal ligament
Posterior, anterior, medial, and lateral capsular thickening 
eversion/inversion control
Anterior part: cervical ligament; floor of sinus tarsi to talar neck 
primarily limits inversion
Lateral talocalcaneal ligament limits inversion, medial talocalcaneal limits eversion
Calcaneofibular ligament: lateral stability to the ankle and subtalar joint
Bifurcate ligament
20° adduction and 10° abduction
Stability
Congruence of the calcaneocuboid joint
Subtalar joint motion (supination 
calcaneocuboid and talonavicular joint axes are not parallel 
close-packed position; midtarsal joint locking)
Ligaments
Medial cuneiform-metatarsal (1st TMT) joint: reciprocal saddle joint similar to 1st carpometacarpal (CMC) joint in hand
Mobile lateral column: 20° flexion/extension versus rigid medial column; cuneiform-2nd MT (<4°)
Osseous, ligamentous (1st cuneometatarsal ligament; large dorsal and broader but inconsistent plantar, inconsistent interosseous, and absent intermetatarsal ligament), and muscles (peroneus longus and flexor halluces longus against dorsal instability)
If stabilizer is dysfunctional 
1st ray hypermobility with compensation mechanism to increase stability with stiffening strategy
Osseous stability
Lisfranc joint: Roman arch configuration, apex at the 2nd MT (transverse arch)
Base of 2nd metatarsal (longer than other metatarsals) in keystone shape; inherent stability
Stability of cuboid-4th metatarsal joint
subluxation/instability
Static: collateral ligaments, capsule, and plantar fascia
Dynamic: peroneus longus and intrinsic muscle of the foot insert to the base of the proximal phalanx, augmented by extrinsic muscles (EHL and FHL)
Anterior talofibular ligament (ATFL)
Two bands, anteromedial, 1 cm proximal to tip of fibula to talar body
Posterolateral to anteromedial course: resist anterior translation and internal rotation of talus
Thinnest of all lateral ligaments: MC injured ligament, not pivotal in gross stability
Superficial: tibiocalcaneal (to sustentaculum tali), tibionavicular, superficial tibiotalar/tibiospring ligament
Deep: deep anterior and posterior tibiotalar ligament (strongest)
Constant: tibiospring, tibionavicular ligament, and deep anterior/posterior tibiotalar ligament
Articular sling around the head of the talus (sling around the head of the talus like acetabulum (with navicular and calcaneus)
Functional spring–ligament complex including anterior portion of superficial deltoid ligament and posterior tibialis tendon (PTT)
Major supporter of medial arch and head of the talus
Control talocalcaneonavicular joint
Plantar and dorsal ligaments: longitudinal, oblique (tarsal to metatarsal bone), and transverse (between metatarsals)
The plantar ligaments are stronger than the dorsal ligaments, which may account for the dorsal direction of dislocations of TMT joints
Interosseous ligaments
The Lisfranc ligament (medial interosseous ligament)
Absent between the bases of the first and second metatarsals and between medial and middle cuneiforms
Lateral portion (stem, frondiform ligament): forms ligament like roots located in the sinus tarsi (15)
underrecognized source of pain
Third interdigital nerve is formed by contribution from both medial and lateral plantar nerves
40% direct branch from the tibial nerve
Flexor digitorum brevis, abductor digiti quinti pedis (ADQP), periosteum medical calcaneus (sensory afferent); no cutaneous innervation
bifurcates into recurrent articular branch, and deep and superficial branch in the lateral leg compartment
Superficial peroneal nerve pierces the deep fascia and becomes subcutaneous 7 to 10 cm above the ankle
Major innervation of cutaneous sensation in the dorsum of the foot except the 1st web space
First-web space cutaneous sensation and afferent sensation from periosteum of sinus tarsi
After bifurcating, the deep peroneal nerve enters anterior compartment under peroneus longus, piercing the intermuscular septum between the lateral and anterior compartment (potential entrapment site)
Deep to EDL to the anterior interosseous membrane (anterior compartment), reaching the anterior tibial artery in the proximal one-third of the leg
At the ankle, it divides into the lateral branch to extensor digitorum brevis (EDB) muscle, sinus tarsi, lateral tarsal joints, and medial terminal branches (lateral to the dorsalis pedis artery)
Roof: inferomedial border of the inferior extensor retinaculum, floor: talonavicular joint capsule
a complex series of compensations that affect all the other articulations of the foot, ankle, and lower extremity
Decreased ankle dorsiflexion (during stance phase) compensated by neighboring (subtalar, midtarsal, knee) joints with pronation response usually
Navicular drop/in rolling (as the compensation response) can cause other problems
In equinus state/deformity, other functional ankle joints compensate for the decreased ankle (tibiotalar) joint motion; sagittal compensation
Functional ankle joints are other neighboring joints that substitute or compensate for an ankle joint motion
Subtalar joint (talocalcaneal) compensation with other components of pronation response kicks during dorsiflexion 
forefoot abduction, navicular drop (in rolling), and hindfoot eversion
Midtarsal (transverse tarsal) joint
Knee joint (knee recurvatum compensate/or secondary to tight Achilles cord)
Shoe (rocker bottom simulating dorsiflexion). Solid ankle cushion heel (SACH) simulating a plantarflexion
Gait changes with ankle osteoarthritis (OA) (22)
Lower walking speed, lower ankle and hindfoot ROM, lower peak-ankle plantarflexion moment and lower peak-ankle power, lower peak-muscle activation of the calf muscles during walking
Dissipates the GRF from an axial to a rotational vector at heel strike
Compensation mechanism to increase stability if midfoot stability compromised: stiffening strategy
Reduced ROM of the 1st metatarsal bone during walking
Disproportionate increase in 1st MT and calcaneal eversion ROM in more challenging activities (eg, stair descent)
limiting the transition from midstance to propulsion in the gait cycle referred to as “sagittal plane blocking”
Picking up the foot early (steppage), rolling-off the medial aspect of the foot abruptly, and shortening the stride on the involved side (limp)
Late and excessive supination, overloading the lateral metatarsals (or causing lateral side foot and lateral leg pain from peroneal overloading)
Flexible, adaptive to irregular surface (initial stance phase)
Stiff, lever arm for push up (late stance phase)
Lever for transmission of plantarflexion force of Achilles tendon (not in other primate)
Medial arch and lateral arch (often neglected, calcaneus, cuboid, 4th and 5th metatarsals, important in Charcot neuroarthropathy progression)
Apex of the arch located at the transverse tarsal (midtarsal) joint medially and laterally (at cuboid)
Key dynamic stabilizers: TP and gastroc-soleus muscle
Three metatarsocuneiform and two metatarsocuboid joints
Roman arch by the wedge-shaped bone (apex at intermediate cuneiform)
Dynamic stabilizers: TP and peroneus longus
imbalance of muscles 
flexible deformity initially with fixed deformity later
Hereditary sensory motor neuropathy (CMT): peroneus brevis and TA primarily affected
hindfoot varus
Foot intrinsic muscle weakness in peripheral neuropathy 
unexposed extrinsic muscles such as EDL and FDL
further shorten plantar fascia—cock-up hallux deformity
Prolonged MTP joint plantarflexion (forefoot supinatus/varus) in cavus foot
By putting the lateral forefoot on the ground, forefoot tilt laterally (forefoot varus) followed by hindfoot inversion; forefoot-driven hindfoot varus
Limited lateral forefoot weight bearing on walking (forefoot already in varus) and functional hallux rigidus (MTP joint dorsiflexion) 
Overusing toe break with pain during walking; at the end of stance phase or MTP joint subluxation
Ankle/subtalar arthropathy, midfoot arthropathy (asymmetric articular buttress)
Overload in the lateral aspect of the foot: peroneal tendinopathy, stress fracture on the metatarsal, and hindfoot varus (inversion): lateral ankle sprain
MTP joint overloading 
MTP subluxation, high arch (plantar fasciitis)
Tight/short plantar fascia; plantar fasciitis
Leg pain (EDL overuse as it becomes major ankle dorsiflexor rather than TA with subtalar axis changes)
Plantar fasciitis with excessive traction to the plantar fascia
Functional hallux rigidus: as the foot rolls inward, the medial column (navicular, medial cuneiform, and first metatarsal) of the foot is elevated or dorsiflexed. Hallux valgus
TP dysfunction (etiology as well as result)
Arthralgia: ankle, subtalar, and talonavicular joint pain, later, calcaneocuboid joint pain by increased stress and asymmetry of forces transmitted through the ankle and subtalar joints
With subtalar neutral, valgus in pes cavus and varus in pes planus (coronal plane)
Toe deformity: claw, hammer toes similar principles to finger deformity
Often deformity is subtle
Normal: 0 to 5, highly pronated: ≥10, highly supinated ≤−5
Lateral malleolar curvature (concave), calcaneal position in coronal plane (eversion), prominence in the region of the talonavicular joint, congruence of medial longitudinal arch, and abduction of the forefoot
Palpation for talar head
Medial malleolus, TP (on medial malleolus)
Navicular tuberosity: prominent bone 1- to 1.5-finger breadth distally/inferiorly (obliquely)
Talonavicular joint: proximal to navicular tuberosity
Naviculocuneiform: distal to navicular tuberosity
Cuneiform-1st MT joint: gap with metatarsal bone movement with shifting distal metatarsal bone (like seesawing a log)
Sustentaculum tali: one-finger breadth below and slightly distal to the medial malleolus (between medial malleolus and navicular tuberosity)
Calcaneal attachment site for calcaneonavicular ligament (spring ligament)
TP (between the medial malleolus and navicular tuberosity, visible with mild resisted hindfoot inversion and forefoot adduction)
Flexor digitorum longus (FDL) superficial to sustentaculum tali, and FHL is below the sustentaculum tali (not palpable)
Groove behind the medial malleolus: TP, FDL, vein, artery, nerves, and FHL (anterior to posterior)
Tenderness on the anterior fibular tip in sprain
Peroneal tendon: visible with resisted eversion
Calcaneocuboid joint: immediately distal to the sinus tarsi
Cuboid-4th metatarsal joint; mobile (compared to cuneiform-metatarsal joints): move the distal part of metatarsal bone while palpating the cuboid-4th metatarsal joint
more prominent in pes planus
Talonavicular joint; N spot; common location for spur or ganglion cyst, can irritate the superficial/deep peroneal nerve
Common location of subtalar joint pain
Gastrocnemius: two joints muscle (across the knee, therefore, ankle plantarflexion tightness worse as knee extends) (30)
Equinus state: <10°, equinus deformity <5° of dorsiflexion
Inspection for other deformities (varus, valgus, and toe deformities)
Often used conceptually for balanced position in deformity (correction to anatomically neutral position can aggravate symptoms in a patient with long-standing deformity)
Normal ROM is a 2:1 (20°:10°) relationship of inversion to eversion
Check rigidity as it affects the decision for treatment (correction versus accommodation)
Beighton scale ≥4, arthralgia >3 months in four joints (revised Brighton Criteria) (32)
widen the mortise
relief of pain indicating fat-pad atrophy
hindfoot varus not corrected (34,35)
positive if it reproduces the pain (lateral forefoot)
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