ANKLE JOINT

The true ankle (talocrural) joint is a saddle-shaped hinge joint between the distal ends of the tibia and fibula and the trochlea of the talus (see Figure 7-2). Most of the body weight is transmitted through the tibia to the talus. The medial (tibial) malleolus and the lateral (fibular) malleolus extend distally to form the ankle mortise that stabilizes the talus and prevents rotation. The joint capsule is lax anteriorly and posteriorly but is strengthened medially by the powerful deltoid ligament and laterally by three distinct bands: the anterior and posterior talofibular ligaments and the calcaneofibular ligament. The synovial cavity does not normally communicate with other joints, adjacent tendon sheaths, or bursae. Tendons crossing the ankle region are invested for part of their course in tenosynovial sheaths (Figures 7-3 and 7-4).

In the anterior (extensor) compartment, the tendons of the tibialis anterior (most medial), extensor hallucis longus, extensor digitorum longus, and peroneus tertius (most lateral) muscles are bound down by the superior and inferior extensor retinaculi (see Figure 7-3). The dorsalis pedis artery runs between the extensor hallucis longus and extensor digitorum longus tendons.

FIGURE 7-3 BURSAE, TENDONS, AND TENDON SHEATHS OF THE ANTERIOR (EXTENSOR) AND PERONEAL COMPARTMENTS OF THE ANKLE.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

In the lateral (peroneal) compartment, the peroneus longus and brevis tendons are enclosed in a single synovial sheath that runs behind and below the lateral malleolus (see Figure 7-3). The superior and inferior peroneal retinaculi strap down the peroneal tendons.

In the medial (flexor) compartment, the tendons of the tibialis posterior (most medial), flexor digitorum longus, and flexor hallucis longus (most lateral) muscles are held down by the flexor retinaculum, forming the tarsal tunnel (see Figure 7-4). The flexor retinaculum bridges the interval between the medial malleolus and the calcaneus. The posterior tibial artery and nerve lie between the tendons of the flexor digitorum longus and the flexor hallucis longus.

FIGURE 7-4 BURSAE, TENDONS, AND TENDON SHEATHS OF THE MEDIAL (FLEXOR) COMPARTMENT OF THE ANKLE.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

Posteriorly, the common tendon of the gastrocnemius and soleus (Achilles tendon or tendocalcaneus) is inserted into the posterior surface of the calcaneus. The tendon does not have a synovial sheath but is surrounded by a loose connective tissue known as paratendon or peritenon. The tendon of the plantaris muscle, which originates from the lateral femoral epicondyle and lateral meniscus, runs obliquely between the soleus and gastrocnemius muscles to insert into the medial aspect of the superior calcaneal tuberosity medial to the Achilles tendon.

Several bursae exist around the ankle (Figure 7-5; also see Figures 7-3 and 7-4). The retrocalcaneal bursa, located between the Achilles tendon insertion and the posterior surface of the calcaneus, is surrounded anteriorly by Kager’s fat pad. The bursa serves to protect the distal Achilles tendon from frictional wear against the posterior calcaneus. The retroachilleal bursa lies between the skin and the Achilles tendon and protects the tendon from external pressure. The subcalcaneal bursa lies beneath the skin over the plantar aspect of the calcaneus. The medial and lateral subcutaneous malleolar, or “last” bursae, are located near the medial and lateral malleoli, respectively.

FIGURE 7-5 BURSAE AROUND THE ANKLE.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

Movements of the ankle include dorsiflexion and plantar flexion (Figure 7-6). The axis of movement passes approximately through the malleoli. The gastrocnemius and soleus muscles are the prime plantar flexors of the ankle. The tibialis anterior and extensor digitorum longus muscles are the prime dorsiflexors.

FIGURE 7-6 ANKLE JOINT: NORMAL RANGE OF DORSIFLEXION AND PLANTAR FLEXION.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

SUBTALAR JOINT

The subtalar (talocalcaneal) joint lies between the talus and the calcaneus and has three facets: anterior, middle, and posterior. Its tight capsule permits little synovial expansion, about 30° of inversion (sole of the foot turned inward), and 10° to 20° of eversion (sole turned outward).

MIDTARSAL JOINT

The midtarsal (transverse tarsal) joint comprises the combined talonavicular and calcaneocuboid joints (see Figure 7-1). The cuboid and navicular are usually joined by fibrous tissue, but a synovial cavity may exist. The midtarsal joint contributes to inversion (supination) and eversion (pronation) movements at the subtalar joint. It also allows 20° of adduction (foot turned toward the midline) and 10° of abduction (foot turned away from the midline). The axis of rotation of the subtalar and midtarsal joints is such that inversion is invariably accompanied by adduction of the forefoot, called supination, and eversion by abduction of the forefoot, called pronation. The tibialis posterior and tibialis anterior, aided by the gastrocnemius, invert the foot. The peroneus longus, peroneus brevis, and extensor digitorum longus evert the foot, aided by the peroneus tertius.

The intertarsal joints between the navicular, cuneiforms, and cuboid are plane-gliding joints that intercommunicate with one another and with the intermetatarsal and tarsometatarsal joints (see Figure 7-1).

METATARSOPHALANGEAL JOINTS

The metatarsophalangeal (MTP) joints are ellipsoid synovial joints that lie about 2 cm proximal to the webs of the toes. Their capsule is strengthened by the collateral ligaments on each side and by the plantar ligament (plate) on the plantar surface. The plantar ligaments are fused with the flexor tendon sheaths and are connected together by the transverse metatarsal ligament, which holds the metatarsal heads together to prevent excessive splaying of the forefoot. Small intermetatarsophalangeal bursae are frequently present between the metatarsal heads (Figure 7-7). The long extensor tendons form the extensor expansions (aponeuroses), which overlay the dorsum of the MTP joints and digits. The intrinsic muscles of the foot—including the flexor hallucis brevis, the lumbricals, the interossei, and the flexor digiti minimi brevis—are partly inserted into the extensor expansions and assist in plantar flexion of the MTP joints. The extensor hallucis longus, extensor digitorum longus, and extensor digitorum brevis dorsiflex the MTP joints. Movements at the first MTP joint consist of dorsiflexion (70° to 90°) and plantar flexion (about 35° to 50°). The other MTP joints permit about 40° dorsiflexion and 40° plantar flexion, as well as a few degrees of abduction (away from the second toe) and adduction (toward the second toe).

FIGURE 7-7 PLANTAR SURFACE OF THE FOOT: FLEXOR TENDON SHEATHS AND BURSAE.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

INTERPHALANGEAL JOINTS

The proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints are hinge joints. The plantar flexors are the flexor hallucis longus and brevis (great toe), the flexor digitorum longus (the lateral four toes at the DIP joints), and the flexor digitorum brevis (the lateral four toes at the PIP joints). The dorsiflexors are the extensor hallucis longus and the extensor digitorum longus and brevis, assisted by the interossei and lumbricals. The digital flexor tendon sheaths enclose the long and short flexor tendons, extending along the length of the toes to the distal third of the sole proximally (see Figure 7-7). A bunion bursa is commonly located over the medial aspect of the first MTP joint. Less frequently, a bursa is present over the fifth metatarsal head (bunionette or tailor’s bunion or bursa; see Figure 7-7).

The PIP joints of the toes do not normally hyperextend, and plantar flexion is limited to approximately 50°. The DIP joints allow 10° to 30° dorsiflexion and 40° to 50° plantar flexion.

ARCHES OF THE FOOT

The arches of the foot are the result of the intrinsic mechanical arrangement of the bones supported by ligaments and intrinsic and extrinsic muscles, particularly the tibialis posterior and anterior muscles. The arches of the foot act as shock absorbers during weight bearing. Each foot has two longitudinal and two transverse arches (Figure 7-8). The medial longitudinal arch is high and flexible and comprises the medial three rays digits—cuneiforms, navicular, and talus—and the calcaneus. It provides a resilient spring for weight bearing and forward propulsion in walking. The lateral two rays, cuboid and calcaneus, constitute the low, more rigid lateral longitudinal arch. The anterior transverse metatarsal arch includes the second, third, and fourth metatarsals and the heads of the first and fifth metatarsals. It becomes flattened on weight bearing but returns to its arched position when the weight is removed. The transverse midtarsal arch is more rigid and lies across the midtarsal region.

FIGURE 7-8 THE FOOT: MEDIAL LONGITUDINAL ARCH AND LIGAMENTS.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

The longitudinal arches are held together by several layers of ligaments: the spring (calcaneonavicular) ligament; the long and short plantar ligaments that join the calcaneus to the metatarsal bases; and, most superficially, the plantar fascia (aponeurosis; see Figure 7-8). The plantar fascia extends anteriorly from the medial calcaneal tuberosity and splits at about the middle of the sole into five bands, one for each toe, to be attached to the transverse metatarsal ligament, the flexor tendon sheaths of the toes, and the proximal phalanges. The plantar fascia acts as a strong mechanical tie for the longitudinal arches by joining the three main weight-bearing points of the foot: the calcaneus, the first metatarsal head (including the two sesamoids), and the fifth metatarsal heads. During “toe off” in the later portion of stance phase, it helps the arch to reform and the foot to become more rigid.

ACHILLES TENDINITIS

Achilles tendinitis usually is caused by repetitive trauma and tendon microtears due to excessive use of the calf muscles, as occurs in ballet dancing; track and field, including distance running and jumping; or from faulty footwear with a rigid shoe counter. Enthesopathy and insertional Achilles tendinitis may also occur in patients with ankylosing spondylitis (AS) or psoriatic arthritis (PsA). The tendon is a common site for gouty tophi, rheumatoid nodules, and xanthomas.

Clinical features include activity-related pain, swelling and tenderness over the distal tendon, and sometimes nodular thickening of the peritenon. Passive dorsiflexion of the ankle intensifies the pain. Two indicators that are often positive are the painful arc sign (movements of the tender, swollen area within the tendon with active dorsiflexion and plantar flexion of the ankle) and the Royal London Hospital test (tenderness on repalpation of a tender, swollen area within the tendon with the ankle in maximum active dorsiflexion and plantar flexion).

Achilles tendon rupture occurs most commonly in active young men, during a burst of unaccustomed physical activity involving forced ankle dorsiflexion or from intense athletic activities, particularly football, basketball, or tennis. It may also occur after minor trauma in elderly individuals with preexisting Achilles tendinitis, in patients with systemic lupus erythematosus or rheumatoid arthritis (RA) who are receiving corticosteroids, or after local corticosteroid injection near the Achilles tendon.

The onset is often sudden, with pain in the region of the tendon, sometimes a faint “pop,” and difficulty walking. Swelling, ecchymosis, tenderness, and sometimes a palpable gap are present at the site of the tear. In partial tendon rupture, active plantar flexion of the ankle may be preserved but painful. In complete rupture, it is still possible to actively plantar flex the ankle by using the adjacent intact flexor tendons. However, the Thompson calf squeeze and the sphygmomanometer tests are positive, and rupture is typically associated with inability to perform a single-leg toe raise on the affected side. Abnormalities of the Achilles tendon can be confirmed by ultrasonography or magnetic resonance imaging (MRI).

Retrocalcaneal, sub-Achilles, or subtendinous bursitis is characterized by posterior heel pain that is aggravated by both activity and passive dorsiflexion of the ankle. Patients may develop a limp, and wearing shoes becomes painful. Tenderness on the posterior aspect of the heel, near the tendon insertion, is the main finding. Bursal distension produces a tender swelling behind the ankle with bulging on both sides of the tendon. Known causes include RA, PsA, and AS. Bursitis may also occur in association with both Achilles tendinitis and Haglund disease (abnormal prominence of the posterior calcaneal tuberosity, often associated with a varus hindfoot, causing chronic irritation of the Achilles tendon and bursa). When viewed from behind, a round, bony swelling can be seen just lateral to the distal part of the Achilles tendon.

Retroachilleal or subcutaneous calcaneal bursitis, also called a pump bump, produces a painful, tender, subcutaneous swelling overlying the Achilles tendon, usually at the level of the shoe counter, and the overlying skin may be hyperkeratotic or reddened. It occurs predominantly in women and is frequently caused by wearing improperly fitting shoes or pumps with a stiff, closely contoured heel counter.

PAINFUL ANKLE DISORDERS

Ankle pain is a common patient complaint caused by a number of MSK disorders. Pathology in the bones, joints, ligaments, or tendons can all be accountable for pain and swelling in the region. The differential diagnosis can be narrowed by identifying the most affected side (medial versus lateral), by history, and on physical exam (Table 7-2).

TABLE 7-2 COMMON ANKLE PAIN BY ANATOMICAL SITE

Ankle sprain is one of the most common sports-related injuries. Most cases will heal spontaneously with supportive therapies. However, surgical management is often needed for two particular ligamentous injuries: a deltoid sprain with the deltoid ligament caught intraarticularly, with widening of the medial ankle mortice; and a high ankle sprain, with a widened inferior tibiofibular syndesmosis, causing real or potential widening of the ankle mortice.

PAINFUL HEEL DISORDERS

Plantar fasciitis is the most common cause of subcalcaneal heel pain (Table 7-3). It results from repetitive microtrauma, which causes microtears of the plantar fascia at its attachment into the medial calcaneal tuberosity. Risk factors include repetitive trauma from athletic activities, occupations that entail excessive standing and walking (e.g., “policeman’s heel”), changes in footwear, reduced ankle dorsiflexion (< 10°), obesity, and pronated everted flat foot (pes planovalgus). It may also occur as an enthesopathy in association with AS or PsA.

TABLE 7-3 PAINFUL HEEL DISORDERS

AS, ankylosing spondylitis; PsA, psoriatic arthritis

Pain on the undersurface of the heel on weight bearing is the principal complaint. The pain is worse when weight is borne after a period of rest, such as in the morning, but eases on walking. Localized tenderness without swelling is present over the plantar surface of the medial calcaneal tuberosity. Passive dorsiflexion of the toes while everting the foot stretches the plantar fascia and often accentuates the discomfort. Radiographs may show a plantar calcaneal spur, which in itself is not the cause of the pain. Ultrasonography and MRI are useful diagnostic modalities.

Subcalcaneal (infracalcaneal) bursitis usually occurs in older persons as a result of repetitive trauma from improperly fitting shoes, falls, pounding the heel with some force, prolonged walking, or recent weight gain. Bursal distension produces a cystic swelling beneath the plantar aspect of the calcaneus. In contrast to plantar fasciitis, dorsiflexion of the MTP joints does not increase the discomfort.

A painful calcaneal fat pad (painful heel pad syndrome) is often confused with plantar fasciitis. The heel pad is normally composed of fibroelastic septa separating closely packed fat cells. Rupture of the septa in elderly, obese patients, during everyday activities or as a result of a sudden severe impact, results in attrition of the heel pad, poor shock absorption, and increased weight-bearing pressure on the calcaneus with reactive bony proliferation. Subcalcaneal heel pain occurs on weight bearing, with tenderness over the heel pad at the posterior weight-bearing portion of the calcaneus. This is in contrast to the more anterior and medial tenderness of plantar fasciitis. Radiographs may show reduction in the volume of the calcaneal fat pad and cortical thickening of the calcaneal tuberosity.

Bilateral plantar and calcaneal traction spurs are common in obese, stout, middle-aged and elderly individuals (Figure 7-9). Traction spurs are frequently asymptomatic, although heel pain may result from a coexistent plantar fasciitis, Achilles tendinitis, or painful heel pad.

FIGURE 7-9 PLANTAR CALCANEAL SPUR.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

Flat foot (pes planus), or flattening of the longitudinal arch, is often asymptomatic but may result in muscle aching with prolonged standing or walking. Loss of the medial longitudinal arch on weight bearing and plantar displacement of both the navicular and the talus are the main findings. In severe cases, the calcaneus is everted (valgus), and the forefoot is abducted with a “too-many-toes sign” when viewed from behind. A callosity often develops over the prominent talar head, and marked wear of the soles of the shoes along the inner side is characteristic. Flat foot may be congenital or acquired, but congenital flat foot is more common and may be either hypermobile or rigid. In the hypermobile or flaccid flat foot, the arch is depressed with weight bearing but re-forms when weight is removed. The subtalar and midtarsal joints are mobile. In the rigid flat foot, there is abnormal fibrous, cartilaginous, or bony bridging between the talus and calcaneus or between the navicular and calcaneus (tarsal coalition). The medial longitudinal arch is absent in all positions, and subtalar movements are limited.

Acquired flat foot may result from hypermobility syndrome, RA, neuropathic arthropathy, or trauma. Excessive weight and faulty footwear, superimposed on a mild congenital hypermobile flat foot, may also result in flat foot in adult life. Chronic tenosynovitis and rupture of the tibialis posterior tendon—the main dynamic stabilizer of the hindfoot against valgus (eversion) deformity, particularly in obese middle-aged women—can lead to a progressive asymmetric flat foot deformity or “collapsed foot.” This is often associated with hindfoot valgus (planovalgus deformity) and forefoot pronation. Typically, the patient has difficulty standing on the tiptoes and ball of the affected foot while the contralateral foot is off the ground (positive single heel-rise test).

Acquired flat foot may be of three types: mobile, with the longitudinal arch depressed only with weight bearing; spastic, with spasm and tenderness of the peroneal muscles; or rigid, as with a collapsed foot fixed in eversion, known as a hyperpronated foot.

SPECIFIC DISORDERS OF THE ANKLE AND FOOT

INSPECTION

The ankle and foot are inspected in both resting and standing positions for evidence of swelling, deformity, erythema, tophi, subcutaneous nodules, or ulcers. Abnormalities of gait are observed while the patient is walking. The gait or walking cycle can be divided into two phases: the stance, or weight-bearing phase, and the swing, or non–weight-bearing phase.

Arthritis of the true ankle joint produces a diffuse swelling anteriorly, obliterating the two small depressions present normally in front of the malleoli. By contrast, ankle tenosynovitis manifests as a linear swelling localized to the distribution of the tendon sheath extending across the joint. Swelling in the region of the Achilles tendon may be caused by tendon rupture, calcaneal bursitis, rheumatoid nodules, or urate tophi.

Arthritis of an intertarsal joint produces a diffuse swelling over the medial and dorsal surfaces of the foot. The exact location of the involved joint can be determined only by palpation. Synovitis of the MTP joint is associated with diffuse swelling on the dorsum of the forefoot that may obscure the extensor tendons. Digital flexor tenosynovitis produces a diffuse, tender swelling over the plantar aspect of the toe (“sausage toe”). Generalized swelling of the ankle and foot is common in edematous states.

In the standing position, the calcaneus normally maintains the line of the Achilles tendon. Normally, the middle of the heel is at 5° to 10° of valgus in relation to the middle of the calf. Deformities of the subtalar joint, which result in eversion (calcaneovalgus) or inversion (calcaneovarus) of the heel, are best observed from behind. Equinus and calcaneus refer to angulation of the ankle in plantar flexion and dorsiflexion, respectively. Inspection while the patient is standing may reveal lowering of the longitudinal arch (pes planus) or increased height of the arch (pes cavus).

The toes are simple extensions of the metatarsals. The first and fifth toes are often slightly deviated toward the middle of the forefoot. Hallux valgus deformity refers to a lateral deviation of the first (great) toe on the first metatarsal greater than 10° to 15° (Figure 7-10). Straightening or medial deviation of the great toe on the first metatarsal is called hallux varus, and hallux limitus refers to painful limitation of dorsiflexion of the first MTP joint. In hallux rigidus, there is marked limitation of movement or immobility of the first MTP joint, usually caused by advanced osteoarthritis (OA). Cock-up or claw toe deformity refers to dorsiflexion of the MTP joint and plantar flexion of both the PIP and DIP joints (Figure 7-11). Hammer toe refers to plantar flexion deformity of the PIP joint, usually associated with dorsiflexion of the MTP and DIP joints (see Figure 7-11). In mallet toe deformity, either the DIP joint is plantar flexed and the PIP joint is neutral, or the PIP joint is plantar flexed and the DIP joint is neutral. It is usually associated with a dorsiflexed MTP joint (see Figure 7-11).

FIGURE 7-10 HALLUX VALGUS DEFORMITY WITH METATARSUS PRIMUS VARUS.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

FIGURE 7-11 TOE DEFORMITIES.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

PALPATION

The ankle joint is palpated with the foot in slight plantar flexion. The joint is supported by the fingers of both hands, while the thumbs firmly palpate the anterior aspect of the joint (Figure 7-12). The capsule and synovial membrane are best palpated over the joint line, just distal to the lower end of the tibia and medial to the tibialis anterior tendon. The margins of a swollen synovium in other locations may be difficult to outline because of the overlying tendons. A large ankle effusion may bulge both medial and lateral to the extensor tendons and produce fluctuance: pressure with one hand on one side of the joint causes a fluid wave to be transmitted to the hand on the other side of the joint. Ankle tenosynovitis produces a superficial, linear, tender swelling that extends beyond the joint margins. The swelling is made more prominent by tightening of the involved tendon. Distension of the lateral and medial “last” bursae produces a localized, oval swelling over the anterolateral and anteromedial aspects of the joint, respectively.

FIGURE 7-12 PALPATION OF THE ANKLE JOINT.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

A painful, tender heel may result from a number of causes. In plantar fasciitis, there is tenderness without swelling at the site of attachment of the plantar fascia to the inferomedial surface of the calcaneus. A painful calcaneal fat pad (painful heel pad syndrome) is associated with local tenderness in the center of the heel. Subcalcaneal bursitis produces a tender swelling on the plantar surface of the calcaneus. In Achilles insertional tendinitis, tenderness is present over the tendon near its insertion into the os calcis. Retroachilleal bursitis is characterized by a tender subcutaneous cystic swelling overlying the Achilles tendon. Retrocalcaneal bursitis produces a more diffuse swelling anterior to the tendon and posterior to the ankle joint. The subtalar joint is too deep to allow for accurate palpation, and effusion can rarely be seen on inspection.

The midtarsal, intertarsal, and tarsometatarsal joints are palpated by using the thumbs on the dorsal surface, while the fingers support the plantar aspect of the foot. Tenderness of the MTP joints can be assessed by gentle compression of the metatarsal heads together with one hand (metatarsal compression test). Each joint is then palpated separately for tenderness or evidence of synovial thickening, using the thumbs over the dorsal surface and the forefingers over the plantar aspect (Figure 7-13). Chronic synovitis of the MTP joints often results in toe deformities, loss of the normal plantar fat pad under the metatarsal heads, callus formation, and forefoot (metatarsal) spread due to weakening of the transverse metatarsal ligament. The interphalangeal joints of the toes are palpated for tenderness, synovial thickening, or effusion using the thumbs and forefingers of both hands.

FIGURE 7-13 PALPATION OF THE SECOND METATARSOPHALANGEAL (MTP) JOINT.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

RANGE OF MOTION

Ankle movements are tested with the knee flexed. The normal range is 15° to 25° of dorsiflexion from the neutral position, with the foot at a right angle to leg, and 40° to 50° of plantar flexion (see Figure 7-6).

Subtalar movements are examined with the ankle in the neutral position. The heel is grasped with one hand, while the other hand stabilizes the distal leg (Figure 7-14). The heel is then turned inward (inversion) to 30° and outward (eversion) to 20°.

FIGURE 7-14 SUBTALAR JOINT: EXAMINATION AND RANGE OF MOVEMENTS.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

To test movements of the midtarsal joint, the talus and calcaneus are stabilized with one hand, while the other hand rotates the forefoot inward (inversion) to 30° and outward (eversion) to 20° (Figure 7-15).

FIGURE 7-15 EXAMINATION OF THE MIDTARSAL JOINT.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

Movements of the first MTP include 70° to 90° dorsiflexion and 35° to 50° plantar flexion. The other MTP joints permit 40° each of dorsiflexion and plantar flexion. The PIP joints allow 50° plantar flexion. The DIP joints permit 10° to 30° dorsiflexion and 40° to 50° plantar flexion.

SPECIAL MANEUVERS

In tarsal tunnel syndrome, the Tinel sign is positive if percussion of the posterior tibial nerve—found immediately behind the posterior tibial artery at the flexor retinaculum, behind the flexor digitorum longus tendon—produces paresthesia in the distribution of one or more of its two branches (the medial and lateral plantar nerves). Similar symptoms can sometimes be induced by simple pressure on the nerve beneath the flexor retinaculum. Inflating a sphygmomanometer cuff around the leg to produce venous congestion may also reproduce the paresthesia (positive tourniquet test). In anterior tarsal tunnel syndrome, the deep peroneal nerve, which travels with the dorsalis pedis artery, is entrapped under the extensor retinaculum, and the Tinel sign is often positive.

Inversion and eversion sprains of the ankle can result in tears of the lateral and medial ligaments, respectively. Inversion sprains are more common and result in a tear of the lateral ligament, particularly its anterior talofibular band. To test the ligament, the distal tibia and fibula are held in one hand, while the calcaneus and talus are drawn forward by the other hand (Figure 7-16). A major tear of the anterior talofibular ligament allows forward movement of the talus on the tibia (positive anterior drawer sign).

FIGURE 7-16 THE ANKLE JOINT: ANTERIOR DRAWER SIGN.

A tear of the anterior talofibular ligament.

(From Hochberg H, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh, UK: Mosby, 2003.)

In partial Achilles tendon rupture, active plantar flexion of the ankle may be preserved but painful. In complete rupture, it is still possible to actively plantar flex the ankle with the adjacent intact flexor tendons; however, gentle squeezing of the calf muscles with the patient lying prone, sitting, or kneeling on a chair produces little or no passive ankle plantar flexion (positive Thompson calf squeeze test). If the Thompson test is equivocal, a sphygmomanometer cuff is inflated to 100 mm Hg around the calf with the patient lying prone and the knee 90° flexed. If the tendon is intact, the pressure rises to about 140 mm Hg with passive dorsiflexion of the ankle; but if the tendon is ruptured, the pressure changes very little (positive sphygmomanometer test). Rupture is typically associated with the inability to perform a single-leg toe raise on the affected side. In deep venous thrombosis of the calf, passive dorsiflexion of the ankle with the patient lying supine causes calf pain (positive Homan sign).