Three bones participate in the ankle joint: the tibia and fibula of the leg, and the talus bone, a tarsal bone. The tibia widens distally, forming the medial malleolus, while the distal fibula also enlarges to form the lateral malleolus. The tibia and fibula articulate distally in the distal tibiofibular joint. The inferior surface is a deep concave, articular surface that becomes the mortise of the ankle joint. The medial and lateral malleoli are bony landmarks that are easily palpated, and provide reference points for palpation of the rest of the ankle. The wedge-shaped rounded trochlea (Latin, pulley) of the talus fits within the mortise formed by the malleoli, creating a synovial hinge joint (1,2,3,4,5,6).

Osteology of the foot includes the tarsal bones, talus, calcaneus, navicular, cuboid, three cuneiform bones, five metatarsal bones, and the phalanges. (Fig. 24.1.1). The transverse talar joint is formed by the anterior articulation of the calcaneus and cuboid bones and the talus and navicular bones. The subtalar joint is between the talus and calcaneus. The tarsometatarsal joint is between the cuneiform bones, the cuboid bone, and the metatarsals. The five metatarsals articulate with the proximal phalanges forming the metatarsophalangeal joints. The joints of the toes are the proximal and distal interphalangeal joints.

The articulations of the tarsal and metatarsal bones and their ligaments form the transverse and longitudinal arches of the foot. The cuboid and cuneiform bones and the metatarsal bases form the transverse arch. The calcaneus, talus, navicular, three cuneiforms, and medial three metatarsal bones form the medial longitudinal arch; and the calcaneus, cuboid, and lateral two metatarsals form the lateral longitudinal arch. These arches permit significant shock absorption by flattening out and springing back during loading of the foot.

The distal tibiofibular joint is felt by placing the fingers anterior to the lateral malleolus, thumb posterior, and gently pinching. The fibula can be mobilized in an oblique anterior-posterior direction. The anterior ankle joint can be felt as a depression between the tendons as they cross the ankle. The talar trochlea is palpated by applying pressure, gently, in this depression as the foot is extended. The prominence formed by the head of the second metatarsal as it articulates with the second cuneiform bone lies just lateral to the long medial extensor tendon, extensor hallucis longus, and deep to the dorsalis pedis artery. The tuberosity of the fifth metatarsal is palpated along the lateral border of the foot.

The distal tibiofibular joint is a fibrous joint, or syndesmosis. Very little mobility is present at this joint; however, as the foot is dorsiflexed,
the wedge-shaped talus exerts enough pressure to open this joint slightly. For this reason, the ankle joint is more stable in dorsiflexion than in volar flexion.

The interosseous membrane is a tough connective tissue sheet between the tibia and fibula. This membrane separates the leg into the anterior and posterior compartments, and then continues to become the interosseous ligament of the distal tibiofibular joint. Anterior and posterior inferior tibiofibular ligaments provide further reinforcement.

The tibiotalar joint is the mortise joint, formed by the distal tibiofibular joint as it articulates with the trochlea of the talus. Plantarflexion (extension) of the ankle is permitted as the talus rocks anteriorly, and dorsiflexion (flexion) occurs as the talar trochlea rocks posteriorly, slightly separating the distal tibiofibular joint. The posterior wall of the mortise joint is formed by a continuation of the inferior tibiofibular ligament, the transverse tibiofibular ligament (Fig. 24.1.2). Blood supply to the tibiotalar joint is from the perforating branch of the fibular artery, and from the medial and malleolar branches of the anterior and posterior tibial arteries. The deep fibular, tibial, and saphenous nerves provide innervation.

There are three articulations of the proximal tarsals. The transverse tarsal or talocalcaneonavicular is a synovial ball-and-socket joint. The subtalar and calcaneocuboid joints are plane synovial-type joints. These joints collectively permit inversion and eversion of the foot through gliding and rotational motions between the tarsals. Intertarsal ligaments are named for their proximal and distal attachments to the tarsals. The spring, or talocalcaneonavicular, ligament is an important structure because it supports the transverse arch of the foot. These joints receive their blood supply from the posterior and anterior tibial, posterior fibular, and lateral tarsal arteries. The medial and lateral plantar nerves innervate the plantar aspect of these joints, while the deep fibular nerve innervates the dorsum.

The distal tarsals articulate with the bases of the metatarsals forming tarsometatarsal joints. These plane joints are synovial with fibrous capsules formed by the dorsal, plantar, and interosseous ligaments. Limited gliding between the bones is permitted. Blood supply is from the lateral tarsal artery, which is a branch of the dorsalis pedis. The deep fibular, lateral plantar, and sural nerves provide innervation.

The bases of the metatarsals articulate with one another in the intermetatarsal joints. These are plane-type synovial joints, which permit limited gliding. The dorsal, plantar, and interosseous ligaments form the fibrous capsules. The lateral tarsal artery provides the blood supply, and the innervation is by the digital nerves.

The metatarsals are long bones that form the plantar surface of the foot. Their heads articulate with the proximal phalanges in the metatarsophalangeal joints. These plane-type synovial joints allow limited gliding. Collateral and plantar ligaments form the fibrous capsules. The lateral tarsal artery provides the blood supply. Innervation is by the digital nerves.

The lateral ankle is stabilized by three ligaments. The anterior talofibular ligament attaches the lateral malleous to the neck of the talus. The posterior talofibular ligament attaches the malleolar fossa to the lateral tubercle of the talus. The calcaneofibular ligament is a round cord that attaches the tip of the lateral malleolus to the lateral calcaneus.

The medial deltoid ligament has three components, the tibionavicular, anterior and posterior tibiotalar, and tibiocalcaneal ligaments. The apex of this triangular ligament makes its proximal attachment at the medial malleolus, and then fans out to attach to the navicular, talus, and calcaneus tarsal bones (Fig. 24.1.3A-B). This ligament supports the ankle during eversion, acts to prevent subluxation, and assists in maintaining the medial longitudinal arch of the foot. Blood supply to the tibiotalar joint is from the malleolar branches of the fibular and anterior and posterior tibial arteries. The deep fibular and tibial nerves innervate this joint.

The bones of the toes are the proximal, middle, and distal phalangeal bones. The great toe has only two phalanges, while the others have three. The interphalangeal joints are hinge-type synovial joints that allow flexion and extension. The collateral and plantar ligaments form the fibrous capsules. The superficial fibular nerve forms the digital nerve. These provide cutaneous innervation to the skin of the dorsum of the foot, and all toes except the lateral surface of the little toe and the adjacent surfaces of the great toe and the second toe. Superficial branches of the lateral and medial plantar nerves, which are continuations of the posterior tibial nerve, supply the plantar surfaces of the toes, and intrinsic muscles of the foot.

Muscles of the ankle and foot are divided into extrinsic and intrinsic muscles. The extrinsic ankle dorsiflexor and toe extensor muscles are housed in the anterior compartment of the leg. The tibialis anterior muscle makes its proximal attachment on the lateral tibial condyle and superior lateral surface of the tibia and interosseous membrane. It narrows into a long tendon that traverses the ankle beneath the extensor retinaculum to attach on the medial and inferior surfaces of the medial cuneiform and base of the first metatarsal. Innervation is the deep fibular nerve (L4-L5). The extensor digitorum longus muscle runs just lateral to the tibialis anterior. Its proximal attachment is to the lateral tibial condyle, and proximal three fourths of the interosseus membrane and fibula. Its long tendon attaches to the middle and distal phalanges of the lateral four toes. The extensor hallucis longus attaches proximally to the middle of the fibula and interosseous membrane. The long tendon attaches to the distal phalange of the great toe. The fibularis tertius is a short muscle that makes its proximal attachment to the distal fourth of the interosseous membrane and fibula, crosses the ankle beneath the extensor retinaculum, and then attaches to the dorsum of the fifth metatarsal. The deep fibular nerve (L5-S1) innervates these three muscles.

These ankle dorsiflexor and toe extensor muscles pass beneath the extensor retinacula of the ankle. These structures are thickenings of the deep fascia of the leg. The superior retinaculum is a Z-shaped structure arising from the medial tibia and medial malleolus and crossing over the extensor tendons to attach on the fibula superior to the lateral malleolus and the cuboid bone. The inferior extensor retinaculum arises from the cuboid, and then crosses from lateral to medial over the long extensor tendons to attach to the first cuneiform bone. A second component arises from the first cuneiform bone, and crosses from medial to lateral to attach to the second metatarsal. Each extensor tendon is housed within a synovial sheath formed as the tendon emerges from the muscle and extending distal to the retinacula. These fluid-filled sacs provide lubrication and fluid pressure to limit impingement by the retinacula.

Plantarflexors of the ankle and flexors of the toes are housed in the posterior compartments
of the leg. The plantarflexors are within the superficial posterior compartment. All of these muscles are innervated by the tibial nerve (S1-S2) and insert into the posterior surface of the calcaneus bone. The gastrocnemius splits forming the inferior borders of the popliteal fossa at the knee. The medial head attaches to the popliteal surface of the femur and just superior to the medial femoral condyle. The lateral head attaches to the lateral femoral condyle. The action of the gastrocnemius depends on the position of the knee. It plantarflexes the foot during knee extension to raise the heel during ambulation and is also a secondary knee flexor. The soleus muscle lies beneath the gastrocnemius within the superficial dorsal compartment of the leg, plantarflexes the ankle, but acts independently from the knee. The plantaris muscle lies between the gastrocnemius and soleus. It is a very thin, long, triangular-shaped muscle that terminates into a very thin, cordlike tendon. Its proximal attachment is above the knee at the lateral supracondylar line of the femur and into the oblique popliteal ligament.

The toe flexors occupy the deep posterior compartment of the leg. The flexor hallucis longus (FHL) attaches proximally to the distal two thirds of the fibula, and distally to the base of the distal phalanx of the great toe. The flexor digitorum longus (FDL) lies medial to the FHL. It attaches proximally to the middle posterior surface of the tibia distal to the attachment of the soleus, and to the fibula by a broad tendon. Its long tendon passes beneath the tendon of its medial neighbor, the tibialis posterior before entering the flexor retinaculum and inserting onto the bases of the distal phalanges of the lateral four toes. The tibial nerve (S2-S3) innervates the FHL and FDL.

The tibialis posterior is the most medial of these three deep muscles, arising from the interosseous membrane, the posterior surface of the tibia distal to the origin of the soleus muscle, and the posterior surface of the fibula. It crosses the ankle beneath the flexor retinaculum between the tendons of the FDL and FHL before inserting on the tuberosity of the navicular, cuneiform, and cuboid bones and onto the bases of the middle three metatarsals. The tibial nerve (L4-L5) innervates the tibialis posterior.

The tarsal tunnel is an arch formed by the medial malleolus and calcaneus bones as its floor, and the flexor retinaculum as its roof. The long tendons of the FDL, tibialis posterior, and FHL traverse the ankle with the posterior tibial artery and the tibial nerve. The tendons within this compartment are housed within synovial sheaths.

Two muscles, the fibularis (peroneus) longus and brevis, evert the foot and weakly plantarflex the ankle. They are extrinsic muscles housed within the lateral compartment of the leg. Their proximal attachments are the head and superior and inferior two thirds of the lateral fibula, respectively. The fibular nerve (L5-S2) innervates these extrinsic muscles.

The intrinsic muscles of the foot make their proximal and distal attachments distal to the ankle. The plantar surface of the foot is organized in four layers (Fig. 24.1.4). The intrinsic muscles and the tendons of the extrinsic muscles are interwoven through these layers. Synovial sheaths encase the flexor and extensor tendons of the toes. Sesamoid bones are carried in the flexor tendons of the great toe.

Innervation of the sole of the foot is by the medial and lateral plantar nerves, which branch into deep and superficial branches. Their terminal branches, the plantar digital nerves, supply the toes.

The skin of the plantar surface of the foot is very thick. Just deep to the skin is a tough, thick layer of plantar fascia. The plantar aponeurosis is a deeper layer of connective tissue with longitudinal fibers running from the medial calcaneus to the distal phalanges.

Any athlete who has a foot and ankle problem should always bring his or her footwear into the examination as well. Shoe defects are recognized as a common source of foot injury (1). Overall wear should be initially assessed, and though many guides exist for how long an athlete can use a shoe, each situation must be evaluated individually. Injury prevention starts with assessing the type and quality of shoes (2). Heavy runners will typically wear down a shoe faster than a lighter runner, but a basketball player may not wear shoes as hard as a competitive tennis player. Shoes can lose more than 40% of their shock-absorbing capacity after 250 to 500 miles. The rule of thumb is to change shoes every 6 months. This will vary with the sport and usage, so knowing the essentials of footwear will help a clinician to
determine the appropriate type of shoe and when to replace it.

Look first at the athlete’s posture while standing and perform a static assessment. Note asymmetries in size, swelling, skin coloring, and shape. Make sure the bony and tendon landmarks are visible and within normal limits.

Look for any skin lesions, such as tinea pedis, nevi, and onychomycosis. Discoloration at the distal toes may indicate ill-fitting shoes. If the athlete is diabetic, the foot must always be examined at every physician visit and checked for discolored lesions and circulation.

Alignment is crucial. Note deviations in the toes and contact points among them. “Hammer toes” can be painful and affect performance, so early detection is helpful. Hallux adductus, especially in the first MTP, leads to bunion formation. Note the callus pattern, for it indicates weight distribution. Skin changes along the medial first MTP joint may signify a friction point and the beginning of a bunion.

Note the hindfoot and its position in reference to the forefoot. The heel may move into valgus or varus upon stance. The arch may be high (cavus) with a rigid supinated foot, or low (planus) with a flexible pronated foot. The forefoot may be rectus (straight) or adductus (curved), which can play a factor in injury if the athlete wears wrong-fitting shoes.

To observe pronation, have the athlete walk away and toward you without socks, shoes, and long pants. Look for depression or collapsing of the arch, rotation of the talus, and shifting of the calcaneus into valgus or varus alignment. More discussion on gait analysis can be found in Chapter 25.

Note the bony landmarks and assess for tissue texture changes and tenderness. Progress systematically, from distal to proximal, or vice versa. Structures to always include in the palpatory examination are the medial and lateral malleoli, calcaneus, fifth metatarsal base, first MTP joint, and the medial plantar fascia insertion on the calcaneus.

In the forefoot, palpate the MTP joints and the distal interphalangeal and proximal interphalangeal joints, noting swelling and tenderness. Palpate along the shafts of the metatarsals and their interspaces. Fullness and tenderness between the third and fourth metatarsal shafts may indicate Morton’s neuroma.

Midfoot sprains can be debilitating and lead to long-term consequences, so palpate the first and second metatarso-cuneiform joints, noting swelling, bogginess, and tenderness on both the dorsal and plantar sides. Moving more proximally, palpate the calcaneocuboid and talonavicular joints. Also find the tarsal navicular tubercle, as the posterior tibialis tendon inserts there.

Note the sinus tarsi location and check for tenderness (Fig. 24.2.4). Sinus tarsi syndrome can be overlooked if the examination is incomplete. Areas of possible impingement are the region anterolateral to the lateral malleolus and the anteromedial talus region (Fig. 24.2.5). Palpate these areas for tenderness or tissue changes.

Palpate the lateral (anterior and posterior talofibular, calcaneofibular) (Fig. 24.2.6) and medial deltoid ligaments of the ankle (Fig. 24.2.7). Note any tissue bogginess or swelling, remembering that normal ligaments are not tender to palpation. Move your fingers
toward the anterior aspect and check the syndesmosis, medial to lateral, distal to proximal.

Feel along the tendons and their sheaths, specifically the Achilles, peroneal, and posterior tibialis tendons. Note swelling, defects, and tenderness. Pay close attention to the tarsal tunnel and its structures.

Pulses. The examiner uses the pad of the index finger to palpate the dorsalis pedis and posterior tibial pulses. The dorsalis pedis is on the dorsal side of the foot around the anterior talar neck, while the posterior tibial artery is found in the tarsal tunnel.