Chapter 21. The Ankle and Foot

At the completion of this chapter, the reader will be able to:

1. Describe the anatomy of the joints, ligaments, muscles, and blood and nerve supply that comprise the ankle and foot complex.

2. Describe the biomechanics of the ankle and foot complex, including the open- and close-packed positions, normal and abnormal joint end-feels, kinesiology, and the effects of open- and closed-chain activities.

3. Outline the purpose and components of the tests and measures of the ankle and foot complex.

4. Perform a detailed examination of the ankle and foot complex, including palpation of the articular and soft tissue structures, range-of-motion (ROM) testing, passive articular mobility tests, and stability tests for the ankle and foot complex.

5. Discuss the significance of the key findings from the tests and measures.

6. Evaluate the total examination data to establish a physical therapy diagnosis.

7. Describe the significance of muscle imbalance in terms of functional muscle performance and the deleterious effects on the lower kinetic chain.

8. Develop self-reliant examination and intervention strategies.

9. Describe the intervention strategies based on clinical findings and established goals.

10. Apply manual techniques to the ankle and foot complex, using the correct grade, direction, and duration.

11. Incorporate appropriate therapeutic exercises into the intervention progression.

12. Evaluate intervention effectiveness in order to progress or modify the intervention.

13. Plan an effective home program and instruct the patient in same.

The ankle and foot is a complex structure of 28 bones (including two sesamoid bones) and 55 articulations (including 30 synovial joints), interconnected by ligaments and muscles.

The foot has undergone a number of evolutionary adaptations, which make it very effective for bipedal locomotion. 1First, the foot has become plantigrade, which allows most of the sole to be a weight-bearing surface. Second, the great toe has come to lie in a position with the other toes and, because of the relative immobility of the first metatarsal at the metatarsophalangeal (MTP) joint, is now relatively nonprehensile. Third, the metatarsals and phalanges have progressively shrunk and become small in comparison to the hypertrophied tarsus. Last, the medial side of the foot has become larger and stronger than that of any other primate.

The ankle joint sustains the greatest load per surface area of any joint of the body. 2Peak vertical forces reach 120% of body weight during walking and they approach 275% during running. 3The joints and ligaments of the ankle and foot complex act as stabilizers against these forces and constantly adapt during weight-bearing activities, especially on uneven surfaces. It is estimated that an average 180-lb man absorbs 76.2 tons on each foot while walking 1 mile and that the same man absorbs 121.5 tons per foot while running 1 mile. 4Approximately 60% of this weight-bearing load is carried out by the rearfoot, and 28% by the metatarsal heads. 5,6Although the ankle and foot complex normally adapts well to the stresses of everyday life, sudden or unanticipated stresses to this region have the potential to produce dysfunction.

The ankle and foot complex is a sophisticated musculoskeletal arrangement designed to facilitate numerous and various weight-bearing and non–weight-bearing functions. 7Anatomically and biomechanically, the foot can be subdivided into the rearfoot or hindfoot (tibia, fibula, talus and calcaneus), the midfoot (the navicular, cuboid, and the three cuneiforms), and the forefoot (the 14 bones of the toes, the five metatarsals, and the medial and lateral sesamoids) ( Table 21-1and Fig. 21-1). The seven tarsal bones occupy the proximal half of the foot (see Fig. 21-1). Although described separately, the joints of the lower leg, ankle, and foot act as functional units and not in isolation. The joints of the foot and ankle, their open- and close-packed positions, and capsular patterns are outlined in Table 21-1. The shapes of the articulating surfaces of the leg and foot are outlined in Table 21-2. An appreciation of the shapes of the articulating surfaces is important when examining the joint glides and when performing joint mobilizations. Most of the stability of the foot and ankle is provided by a vast array of ligaments ( Table 21-3).

The joints of the rearfoot are the tibiofibular joint, talocrural (ankle) joint, and the subtalar (talocalcaneal) joint. The proximal row of tarsals comprises the talus (astragalus) (see Fig. 21-1), and calcaneus (or calcis). The function of the rearfoot is as follows:

• to influence the function and movement of the midfoot and forefoot;
• to convert the transverse rotations of the lower extremity into sagittal, transverse, and frontal plane movements. 8

The joints of the midfoot include the talocalcaneonavicular joint, cuneonavicular joint, cuboideonavicular joint, intercuneiform joints, cuneocuboid joint, and the calcaneocuboid joint. The distal tarsal row contains, medial to lateral, the medial, intermediate, and lateral cuneiforms and the cuboid, which is roughly in parallel with the proximal row and which forms a transverse arch, posteriorly (dorsally) convex. Medially, the navicular is positioned between the talus and the cuneiforms (see Fig. 21-1). Laterally, the cuboid is positioned between the calcaneus and the lateral cuneiform and the fourth and fifth metatarsals (see Fig. 21-1). The function of the midfoot is to transmit motions from the rearfoot to the forefoot and to promote stability. 8

The joints of the forefoot include the tarsometatarsal joints, the intermetatarsal joints, the MTP joints, and the interphalangeal (IP) joints. The function of the forefoot is to adapt to the terrain, adjusting to uneven surfaces. The first metatarsal is the shortest and the strongest (see Fig. 21-1), whereas the second is the longest and the least mobile, serving as the anatomic touchstone for abduction and adduction of the foot. 9The phalanges of the foot, although similar in number and distribution to those in the hand, are shorter and broader than their counterparts.

The distal tibiofibular joint ( Fig. 21-1) is classified as a syndesmosis, except for approximately 1 mm of the inferior portion, which is covered in hyaline cartilage. The joint consists of a concave tibial surface and a convex or plane surface on the medial distal end of the fibula. There is an elongation into the joint by the synovium of the talocrural joint, the fibers of which are oriented inferiorly and laterally. The fibula serves as a site for muscular and ligamentous attachment, providing stability for the talus at the talocrural joint. The tibia is the second longest bone of the skeleton and is a major weight-bearing bone.

As at the proximal tibiofibular joint (see Chap. 20), support for this joint is provided primarily by ligaments. The joint is stabilized by four ligaments, collectively known as the syndesmotic ligaments. These include the inferior interosseous ligament, the anterior inferior tibiofibular ligament, the posterior inferior tibiofibular ligament, and the inferior transverse ligament. Of these ligaments, the inferior interosseous ligament is the primary stabilizer.

The talocrural (tibiotalar) joint is the articulation between the talus and the distal tibia. The talus serves as the link between the foot and the leg through the ankle joint and functions to distribute the body weight posteriorly toward the heel and anteriorly to the midfoot. The talus is divided into an anterior head and a posterior neck and body:

• Body.The superior dome-shaped surface of the body articulates with the tibia. The body is convex in the anteroposterior (A-P) direction and slightly concave in the mediolateral (M-L) and superior directions. The shape of this articulating surface can be compared with that of a cone, with the base of the cone facing laterally and the apex medially. Since the superior aspect of the body of the talus is wedge shaped with the wider portion anterior, no varus/valgus movement is possible when the ankle is positioned in maximum dorsiflexion, unless the mortise or the tibiofibular ligaments are compromised.
• Neck.The neck of the talus is a narrow region between the head and the body of the talus, and it is medially inclined. Its rough surfaces serve as attachments for ligaments. Inferior to the neck of the talus is the sulcus tali, which, when the talus and the calcaneus are articulated, roofs the sinus tarsi and is occupied by the talocalcaneal interosseous and cervical ligaments.
• Head.The plantar surface of the head has three articular areas separated by smooth ridges. The most posterior and largest of the articular areas is oval, slightly convex, and rests on a shelf-like medial calcanean projection called the sustentaculum tali. The other two articulating facets connect the talus with the navicular and the plantarcalcaneonavicular ligament.

The medial malleolus extends distally to approximately one-third of the height of the talus, whereas the lateral malleolus extends distally to approximately two-thirds the height of the talus.

The fibrous capsule of the ankle joint is relatively thin on its anterior and posterior aspects. It is lined with synovial membrane and reinforced by the collateral ligaments (see later).

The talus receives its blood supply from the branches of the anterior and posterior tibial arteries and is very susceptible to aseptic necrosis, particularly with proximal fractures. 10

Talocrural Ligaments

The most important ligaments of the talocrural joint can be divided into two main groups: lateral collaterals and medial (deltoid) collaterals.

Lateral Collaterals

The lateral collateral ligament complex consists of three separate bands, which function together as the static stabilizers of the lateral ankle. Each of the lateral ligaments has a role in stabilizing the ankle and/or subtalar joint, depending on the position of the foot. As such, these ligaments are commonly involved in ankle sprains. 11– 15

Anterior Talofibular Ligament

This thickening of the anterior capsule extends from the anterior surface of the fibular malleolus, just lateral to the articular cartilage of the lateral malleolus, to just anterior to the lateral facet of the talus and to the lateral surface of the talar neck ( Fig. 21-2).

The anterior talofibular ligament (ATFL) is an intracapsular structure and is approximately 2–5-mm thick and 10–12-mm long. 16The ATFL functions to resist ankle inversion in plantarflexion. Regardless of ankle position, the ATFL is usually the first ankle ligament to be torn in an inversion injury. 16The accessory functions of the ATFL include providing resistance against anterior talar displacement from the mortise and resistance against internal rotation of the talus within the mortise. 17

Calcaneofibular Ligament

The calcaneofibular ligament (CFL) (see Fig. 21-2), an extra-articular structure covered by the fibular (peroneal) tendons, is larger and stronger than the ATFL. It fans out at 10–40 degrees from the tip of the fibular malleolus to the lateral side of the calcaneus, paralleling the horizontal axis of the subtalar joint. This ligament effectively spans the ankle and subtalar joints, which have markedly different axes of rotation. 18– 21Thus, its attachment is designed so that it does not restrict motion in either joint, whether they move independently or simultaneously. 20, 22, 23As the ankle joint passes from dorsiflexion to plantarflexion, the CFL is less able to resist talar tilt to inversion, although the ATFL is more able to resist this tilt. 22

Posterior Talofibular Ligament

The posterior talofibular ligament (PTFL) (see Fig. 21-2) is the strongest of the lateral ligament complex, 16and serves to indirectly aid talofibular stability during dorsiflexion due to its anatomic location, where it can act as a true collateral ligament and prevent talar tilt into inversion. 22, 24The PTFL is rarely injured except in severe ankle sprains. The ligament is coalescent with the joint capsule, and its orientation is relatively horizontal. Its attachment on the talus involves nearly the entire nonarticular portion of the posterior talus to the groove for the flexor hallucis longus (FHL) tendon, and anteriorly to the digital fossa of the fibula, which transmits the vessels that supply the talus and the fibula. 25, 26

Lateral Talocalcaneal Interosseous

The lateral talocalcaneal interosseous (LTCIL) ligament is sometimes included in this group as it does play a role in lateral ankle and subtalar stability (see Talocalcaneal Ligaments). 16, 27

Besides maintaining lateral ankle stability, the lateral ankle ligaments play a significant role in maintaining rotational ankle stability. 22Significant compromise to the ATFL and/or CFL leads to a measurable increase in inversion without any tilting of the talus or subtalar gapping. 22A loss of ATFL function permits an increase in external rotation of the leg and unlocks the subtalar joint, allowing further inversion, which may lead to symptomatic instability. 22

Medial Collaterals

Collectively, the medial collateral ligaments form a triangular-shaped ligamentous structure known as the deltoid ligament of the ankle ( Fig. 21-3). Wide variations have been noted in the anatomic description of the deltoid ligament of the ankle but is generally agreed that it consists of both superficial and deep fibers. The superficial fibers consist of the following:

• Tibionavicular fibers (seeFig. 21-3).These fibers extend from the medial malleolus to the tuberosity of the navicular and serve to resist lateral translation and external rotation of the talus.
• Posterior talotibial fibers (seeFig. 21-3).These fibers travel in a posterolateral direction from the medial malleolus to the medial side of the talus and medial tuberosity of the talus. These fibers resist ankle dorsiflexion and lateral translation and external rotation of the talus.
• Calcaneotibial fibers (seeFig. 21-3).These thin fibers extend from the medial malleolus to the sustentaculum tali. The fibers are oriented in such a way that they resist abduction of the talus, calcaneus, and navicular, when the foot and ankle are positioned in plantar flexion and eversion. 19

The deep fibers consist of the following:

• Anterior talotibial fibers (seeFig. 21-3).The fibers of this strong ligament extend from the tip of the medial malleolus to the anterior aspect of the medial surface of the talus. These fibers are oriented in such a way that they resist abduction of the talus, when it is in plantar flexion and eversion. Such is the strength of these fibers that an injury to this ligament is often associated with an avulsion fracture.

Although the calcaneotibial ligament is very thin and supports only negligible forces before failing, the talotibial ligaments are very strong. 31, 32Rasmussen et al. 33, 34found that the superficial fibers of the deltoid ligament of the ankle specifically limited talar abduction or negative talar tilt and that the deep layers of the deltoid ligament of the ankle ruptured with external rotation of the leg, without the superficial portion being involved.

The subtalar joint consists of two separate, modified ovoid surfaces with their own joint cavities. The two anterior and posterior articulations are connected by an interosseous membrane.

• The anterior joint consists of a concave facet on the calcaneus and a convex facet on the talus. The anterior component is situated more medial than the posterior, giving the plane of the joint an average 42 degrees (±9 degrees) superior from the transverse foot plane and 23 degrees (±11 degrees) medial from the sagittal foot plane. 36
• The posterior joint consists of a convex facet on the calcaneus and a concave facet on the talus.

This relationship ensures that the anterior and posterior aspects can move in opposite directions to each other during functional movements (while the anterior aspect is moving medially, the posterior aspect is moving laterally).

The calcaneus, the largest tarsal bone and the most frequently fractured, projects further posteriorly than the tibia and fibula. It serves as a weight-bearing bone and as a short lever for muscles of the calf, which are attached to its posterior surface. The skin and fat over the distal-inferior area of the calcaneus are specialized for friction and shock absorption. 37

The retrocalcaneal bursa lies anterior to the posterosuperior calcaneal tuberosity of the calcaneus. It lubricates the Achilles tendon anteriorly, as well as the superior aspect of the calcaneus. 39The superior or proximal surface of the calcaneus is divisible into thirds.

• The posterior third.This is a roughened surface that is concavoconvex in extension, the convexity transverse. It supports fibroadipose tissue between the calcaneal tendon and the ankle joint. Distal to the posterior articular facet is a rough depression that narrows into a groove on the medial side—the sulcus calcanei—which completes the sinus tarsi with the talus.
• The middle third.This surface carries the posterior talar facet and is oval and convex anteroposteriorly.
• The anterior third.This surface is only partly articular.

Talocalcaneal Ligaments

A number of ligaments provide support to this joint, although some confusion exists in the descriptions and nomenclature of these ligaments. In relation to the sinus tarsi, the most medial ligament is the talocalcaneal interosseous ligament, which branches superiorly into medial and lateral bands. 22The cervical ligament and portions of the retinaculum are located more laterally. The talocalcaneal interosseous and cervical ligaments are often collectively referred to as the interosseous ligaments. 41

Medial (Posterior) Talocalcaneal Interosseous

The medial talocalcaneal interosseous ligament extends from the medial tubercle of the talus to the posterior aspect of the sustentaculum tali and the area of the calcaneus just posterior to the sustentaculum tali. It functions to stabilize against anterior translation of the talus (especially at the initial contact phase of the gait cycle) by producing passive eversion of the talus. This results in a close packing of the lateral foot and fibula. Damage to this ligament, which typically occurs with inversion sprains and rotational compression fractures of the calcaneus, can permit excessive anterior motion of the talus. This excessive motion may result in posterior tibialis tendinitis 42and on occasion, Achilles' tendinitis. 43

Lateral (Anterior) Talocalcaneal Interosseous

The lateral (anterior) talocalcaneal interosseous ligament (LTCIL) originates from the roof of the sinus tarsi and extends in a posteroinferior direction from the lateral process of the talus to the lateral surface of the calcaneus, just anterior to the CFL. This ligament functions to prevent the talus and the calcaneus from separating during inversion movements. This highly innervated structure is typically injured with a dorsiflexion and inversion mechanism. 44

The midtarsal joint complex consists of the talonavicular and calcaneocuboid articulations.

Talonavicular

The talonavicular joint is classified as a synovial, compound, modified ovoid joint.

The joint is actually formed by components of the talus, navicular, calcaneus, and plantar calcaneonavicular (spring) ligament. The rounded convex anterior head of the talus fits into the concavity of the posterior navicular and the anterior component of the subtalar joint and rests on the posterior (dorsal) surface of the spring ligament. The joint capsule is only well developed posteriorly, where it forms the anterior part of the interosseus ligament.

Calcaneocuboid

The calcaneocuboid joint is classified as a simple, synovial, modified sellar joint.

The anterior surface of the calcaneus, which articulates with the reciprocally shaped posterior surface of the cuboid, is relatively convex in an oblique horizontal direction and relatively concave in an oblique vertical direction. 45The cuboid, most lateral in the distal tarsal row, is located between the calcaneus proximally and the fourth and fifth metatarsals distally. To the posterior (dorsal) surface are attached posterior (dorsal) calcaneocuboid, cubonavicular, cuneocuboid, and cubometatarsal ligaments, and to the proximal edge of the plantar ridge, deep fibers of the long plantar ligament. To the projecting proximal–medial part of the plantar surface are attached a slip of the tendon of tibialis posterior and flexor hallucis brevis (FHB). To the rough part of the medial cuboidal surface are attached the interosseous, cuneocuboid, and cubonavicular ligaments, and proximally the medial calcaneocuboid ligament, which is the lateral limb of the bifurcated ligament. 46The capsule is thickened posteriorly (dorsally) to form the posterior (dorsal) calcaneocuboid ligament. The joint has a large plantar phalanx to provide additional support during weight-bearing.

A number of ligaments help provide support to this region. The spring ligament (plantar calcaneonavicular Fig. 21-3) connects the navicular bone to the sustentaculum tali on the calcaneus. The ligaments of the calcaneocuboid joint include the long plantar ligament and a portion of the bifurcate ligament posterior (dorsally).

• The long and strong plantar ligament attaches to the plantar surface of the calcaneus, the tuberosity on the plantar surface of the cuboid bone, and to the bases of the second, third, and fourth (and possibly fifth) metatarsals. 46The plantar ligament functions to provide indirect plantar support to the joint, by limiting the amount of flattening of the lateral longitudinal arch of the foot. 47Together with the groove in the cuboid bone, it forms a tunnel for the passage of the fibularis (peroneus) longus tendon across the plantar surface of the foot. 46
• The bifurcate ligament functions to support the medial and lateral aspects of the foot when weight-bearing in a plantar flexed position (twisted).

The plantar calcaneocuboid ligament, sometimes referred to as the short plantar ligament, is a relatively broad and strong strap-like structure that extends from the area of the anterior tubercle of the calcaneus to the adjacent plantar surface of the cuboid bone. It provides plantar support to the joint and possibly helps to limit flattening of the lateral longitudinal arch.

The cuneonavicular joint is classified as a compound, synovial, modified ovoid joint. The navicular presents a convex surface to the concave surface of the combined cuneiforms. The wedge-like cuneiform bones articulate with the navicular proximally and with the bases of the first to third metatarsals distally (see Fig. 21-1). The medial cuneiform is the largest and the intermediate, the smallest. In the intermediate and lateral cuneiforms, the posterior (dorsal) surface is the base of the wedge, but in the medial, the wedge is reversed, a prime factor in shaping the transverse arch. The wedge shape of these bones also provides a cavity for the neurovascular and musculotendinous structures of the foot.

The cuneiforms, together with articulations with the metatarsal bones, form Lisfranc's joint. 9The proximal surface of all three cuneiforms form a concavity for the convex surface of the navicular. In the intermediate and lateral cuneiforms, the posterior (dorsal) surface is the base of the wedge, but in the medial, the wedge is reversed, which assists in the formation of the transverse arch. The medial cuneiform is the largest, the intermediate the smallest. The ligament of Lisfranc runs between the medial cuneiform and second metatarsal base. Disruption of this ligament can lead to a dislocation of the medial aspect of the foot, as the first metatarsal and medial cuneiform separate from the second metatarsal and intermediate cuneiform.

The joint cavity and capsule of the cuneonavicular joint is continuous with that of the intercuneiform and cuneocuboid joints, and the synovium is continuous with that of these joints, the second and third cuneometatarsal joints, and the intermetatarsal joints of each base except the fifth.

These joints (see Fig. 21-1) are classified as compound, synovial, modified ovoid joints. The joint capsule and synovium is contiguous between all of these joints and with that of the cuneonavicular joint.

Dysfunctions in the cuneocuboid joint result from a collapse of the plantar supporting structures or from direct trauma. Such dysfunctions may result in the cuboid subluxing in a plantar direction (medial border of cuboid moves inferiorly). At the intercuneiform joints, the third cuneiform may sublux on the second cuneiform.

Laterally, the cuboid bone articulates with the fourth and fifth metatarsals distally, and with the calcaneus proximally. When considered alone, the cubometatarsal joint is classified as a compound, modified ovoid, synovial joint. When the cubometatarsal joints are considered together, they form a modified sellar joint. The joint capsule and synovium of the fourth and fifth cubometatarsal joints are separated from the other tarsometatarsal joints by an interosseous ligament.

The cubonavicular joint (see Fig. 21-1) is classified as a syndesmosis or a plane surfaced joint. If the joint is synovial, the capsule and synovium is continuous with the cuneonavicular joint.

The first intermetatarsal joint (see Fig. 21-1) is classified as a simple, synovial, modified ovoid joint, whereas the second, third, and fourth are classified as compound joints. If the joint is synovial, the capsule and synovium is continuous with the cuneonavicular joint. Motion at these joints is confined to posterior (dorsal)/anterior (plantar) gliding, producing a fanning and folding motion of the foot. Proximally, the five metatarsals articulate with the tarsals and with themselves through broad concavities. 9

The MTP joints (see Fig. 21-1) are classified as simple, synovial, modified ovoid joints. The capsule and synovium in each of these joints is confined to its own joint and posteriorly (dorsally) is thin, whereas plantarly (anteriorly), it is blended with the plantar and collateral ligaments. Rotation occurring in the early stages of development of the limbs results in the thumb being the most lateral digit in the hand, whereas the hallux (great toe) is the most medial digit in the foot. 48The concave bases of the proximal phalanges (see Fig. 21-1) articulate with the convex heads of the metatarsals. The first MTP joint, with its more extensive articular surface on the anterior (plantar) aspect of the metatarsal than on the posterior (dorsal), allows for a greater freedom of motion, 48and its anterior (plantar) surface forms two grooves for articulation with the hallucal sesamoids (see next section). The fifth metatarsal has a lateral styloid process at its base, which serves as the insertion site for the tendon of the fibularis (peroneus) brevis. The styloid area is often avulsed during acute inversion injuries of the foot. 9Three types of forefoot are recognized based on the length of the metatarsal bones, although it is unclear whether these various types affect foot function in any way 48:

• Index plus.This type is characterized by the first metatarsal being longer than the second, with the other three of progressively decreasing lengths, so that 1 > 2 > 3 > 4 > 5.
• Index plus–minus.In this type, the first metatarsal is of the same length as the second, with the others progressively diminishing in length, so that 1 = 2 > 3 > 4 > 5.
• Index minus.With this type, the second metatarsal is longer than the first and third metatarsals. The fourth and fifth metatarsals are progressively shorter than the third, so that 1 < 2 > 3 > 4 > 5.

Stability of the MTP joints is primarily provided by a musculocapsular ligamentous complex anteriorly (plantarly), and medially and laterally by the medial and lateral collateral ligaments, respectively.

First MTP Joint

The first MTP joint is the articulation between the head of the first metatarsal and the proximal phalanx. Although there is some anatomic variation from patient to patient, the first MTP joint is typically a cam-shaped, condylar-hinged joint. 49The MCP joint has little inherent stability because the proximal phalanx has a fairly shallow cavity in which the metatarsal head articulates. The joint is stabilized posteriorly (dorsally) by the capsule and expansion of the extensor hallucis tendon. Fan-shaped medial and lateral collateral ligaments provide valgus and varus stability, respectively. The plantar surface of the capsule is reinforced by a fibrocartilaginous plate, called the plantar accessory ligament. In addition, the MTP joints are dynamically stabilized by the short flexor complex (FHB and the two sesamoids embedded in the FHB tendons), the adductor hallucis, and the abductor hallucis tendons.

The sesamoids are connected distally to the base of the proximal phalanx by extensions of the FHB called the plantar plate. Typically, the sesamoids are anterior (plantar) to the medial and lateral condyles of the metatarsal pad. The sesamoids are separated on the anterior (plantar) aspect of the first metatarsal head by a cresta, which helps to stabilize the sesamoids, and are connected to one another by the intersesamoidal ligament. The abductor hallucis inserts into the medial sesamoid, and the adductor hallucis inserts into the lateral sesamoid. The FHL ( Fig. 21-4) pierces the two heads of the FHB muscle to run just anterior (plantar) to the intersesamoidal ligament. In normal gait, the capsuloligamentous complex of the first MTP joint must withstand 40–60% of body weight, but in athletic activity, this can reach as much as eight times body weight. 47, 51– 56

The hallux has two phalanges, whereas each of the remaining toes have three (see Fig. 21-1). The IP joints are classified as simple, synovial, modified sellar joints. The saddle-shaped articular fossa of the head of the proximal phalanx articulates with the base of the intermediate phalanx. This in turn receives the smaller and flatter distal phalanx.

An accessory ossicle (accessory bone) is an anomalous bone that fails to unite during developmental ossification. Common locations include the fibular malleolus, tibiar malleolus, navicular, and talus.

The accessory navicular is the most common accessory bone in the foot. 57It occurs on the medial, anterior (plantar) border of the navicular, at the site of the tibialis posterior tendon insertion. 58The incidence in the general population has been reported to be 4–14% 58, 59The posterior aspect of the talus often exhibits a separate ossification center, appearing at 8–10 years of age in girls and 11–13 years of age in boys. Fusion usually occurs 1 year after its appearance. 60, 61When fusion does not occur, an os trigonumis formed (see “Pathologies” section).

The terms plantar fasciaand plantar aponeurosis( Fig. 21-4) are often used interchangeably, although strictly speaking only the central part of the plantar fascia is extensively aponeurotic. 63The plantar fascia is the investing fascial layer of the anterior (plantar) aspect of the foot that originates from the os calcis and inserts through a complex network to the anterior (plantar) forefoot. It is a tough, fibrous layer, composed histologically of both collagenand elastic fibers. The plantar fascia is often regarded as being analogous to the palmar fascia of the hand. However, unlike the fascial layer of the palm, which is generally thin, the plantar fascia is a thick structure, and not only serves a supportive and protective role, but is also intricately involved with the weight-bearing function of the foot. 63The plantar fascia is divided into three major areas: a central portion and medial and lateral sections, each oriented longitudinally on the anterior (plantar) surface of the foot. 26

• Central portion.The central portion is the major portion of the plantar fascia both anatomically and functionally. 63This portion is the thickest and the strongest and is narrowest proximally where it attaches to the medial process of the calcaneal tuberosity, proximal to the flexor digitorum brevis (FDB). This attachment site is often involved in a condition called plantar heel pain (see “Intervention Strategies”section); however, pain can occur anywhere along the structure. From its insertion, the central portion of the fascia fans out and becomes thinner distally. Its fibers are longitudinally oriented and adhere to the underlying FDB muscle. 63The central portion envelops the FDB muscle on both sides, forming the medial and lateral intermuscular septums, which anchor the plantar fascia to the deep plantar pedis. 63At the midshaft of the second to fifth MTP joints, the body of the central portion branches into five superficial longitudinal tracts. 63All five superficial longitudinal tracts terminate by inserting into, and blending with, the overlying subcutaneous tissues and skin. Due to the anatomical connections of the central portion, dorsiflexion of the toe slides the plantar pads distally, placing tension on the plantar aponeurosis. The central portion of the fascia primarily functions as a dynamic stabilizer of the medial longitudinal arch during weight-bearing activities.
• Lateral and medial portions.The smaller and thinner lateral and medial portions are thin and cover the under surface of the abductor digiti minimi and abductor hallucis muscles, respectively.

With standing and weight-bearing, the plantar fascia plays a major role in the support of the weight of the body, by virtue of its attachments across the longitudinal arch. During the different phases of gait, the plantar fascia assumes different biomechanical functions. For example, during the toe-off portion of the gait cycle, the windlass effect on the plantar fascia helps to reconstitute the arch and generates a more rigid foot for propulsion. ^ch21fn162During heel strike, and during the first half of the stance phase of the gait cycle with the toes in neutral, the plantar fascia relaxes, flattening the arch. This allows the foot to accommodate to irregularities in the walking surface and to absorb shock. 62As the foot proceeds from midstance to terminal stance, the toes dorsiflex and, through its attachments to the toes via the plantar plate, the plantar fascia tightens. The plantar fascia is pulled over the metatarsal heads, causing the metatarsal heads to be depressed and the longitudinal arch to rise. 63During the swing phase of gait, the plantar fascia is under little tension and appears to serve no important functional role.

There are four important ankle retinacula, which function to tether the leg tendons as they cross the ankle to enter the foot ( Fig. 21-4). 64

• Extensor retinaculum.The extensor retinaculum consists of two parts: superior and inferior. The superior part functions to contain the tendons of the extensor digitorum longus, extensor hallucis longus, tibialis anterior, and fibularis (peroneus) tertius. The Y-shaped inferior part consists of an upper and a lower band, which prevent “bow-stringing” of the posterior (dorsal) tendons.
• Superiofibular (peroneal) retinacula.This firmly tethers the fibularis (peroneus) longus and brevis tendons behind the fibular malleolus.
• Flexor retinaculum.The flexor retinaculum provides a firm support structure for the flexor digitorum longus, FHL, tibialis posterior, and the neurovascular bundle.

*The orientation of the aponeurosis promotes inversion of the calcaneus and supination of the subtalar joint when it is under tension, which raises the longitudinal arch and provides a rigid lever for propulsion.

The extrinsic muscles of the foot ( Table 21-4) can be divided into anterior, posterior superficial, posterior deep, and lateral compartments.

Anterior Compartment

This compartment contains the dorsiflexors (extensors) of the foot. These include the tibialis anterior, extensor digitorum longus, and extensor hallucis longus (see Fig. 21-5).

Posterior Superficial Compartment

This compartment, located posterior to the interosseous membrane, contains the calf muscles that plantar flex the foot. These include the gastrocnemius, soleus (see Fig. 21-5), and the plantaris muscle ( Fig. 21-6).

Triceps Surae

The triceps surae comprises the two heads of the gastrocnemius, which arise from the posterior aspects of the distal femur, and the soleus, which arises from the tibia and fibula, which combine to form the Achilles tendon. 65The medial head of the gastrocnemius is by far the largest component and, according to electromyographic (EMG) studies, is the most active of the two during running. 66, 67The soleus ( Fig. 21-5), because it does not cross the knee joint, is subject to early disuse atrophy with undertraining and/or immobilization. 66The Achilles tendon is formed from the conjoint tendons of the gastrocnemius and soleus muscles. The fibers from the gastrocnemius and soleus interweave and twist as they descend, producing an area of high stress 2–6 cm above the distal tendon insertion. 68A region of relative avascularity exists in the same area, 69which correlates well with the site of some Achilles tendon injuries, including complete spontaneous rupture. 66, 70, 71The plantaris muscle has its own tendon and contributes no fibers to the Achilles tendon. 72

Achilles Tendon

The Achilles tendon is the thickest, strongest tendon in the body. 65As the Achilles tendon comes off the posterior calf muscles, it courses distally to attach approximately three-quarters of an inch below the superior portion of the os calcis, on the medial aspect of the calcaneus. Two bursae occur at the point of insertion of the Achilles tendon into the calcaneus. The retrocalcaneal bursa lies deep into the tendon, adjacent to the calcaneus. The superficial bursa of the tendo achillis lies superficial to the distal portion of the tendon, between the tendon itself and the subcutaneous tissues, but is not visible unless it is pathologically inflamed. Deeper to the Achilles tendon is the pre-Achilles fat pad, a triangular area of adipose tissue, also known as Kager's triangle. Further anterior to this fat pad are the deep flexor tendons of the calf, predominantly the FHL, which overlies the posterior tibia and the talus.

There is no synovial sheath surrounding the Achilles tendon. The peritendon covers the endotendon and is composed of a thin sheath, called the epitenon, and another fine outer sheath, the peritenon, composed of fatty areola tissue, which fills the interstices of the fascial compartment in which the tendon is situated. 73The peritenon is able to stretch 2–3 cm with tendon movement, which allows the Achilles tendon to glide smoothly. 74

Posterior Deep Compartment

This compartment contains the flexors of the foot. These muscles course behind the medial malleolus. They include the posterior tibialis, flexor digitorum longus, and FHL (see Fig. 21-7).

The primary function of the tibialis posterior muscle is to invert and plantar flex the foot. It also provides support to the medial longitudinal arch. 75The flexor digitorum longus functions to flex the phalanges of the lateral four toes and assists with plantar flexion of the foot.

The FHL flexes the great toe and also assists with plantar flexion of the foot.

Lateral Compartment

This compartment contains the fibularis (peroneus) longus and brevis (see Fig. 21-5). The fibular (peroneal) tendons lie behind the lateral malleolus in a fibro-osseous tunnel formed by a groove in the fibula and the superficial fibular (peroneal) retinaculum. The fibular (peroneal) retinaculum and the posterior CFL form the posterior wall of this tunnel.

Beneath the plantar aponeurosis–plantar fascia are the four muscular layers of the intrinsic muscles of the anterior (plantar) foot ( Table 21-5), as well as the plantar ligaments of the rear- and midfoot. The intrinsic muscles provide support to the foot during propulsion. 79

First Layer

The first layer is the most anterior (plantar) and consists of the following:

• Abductor hallucis (Fig. 21-8). This muscle arises from the medial process of the calcaneal tuberosity and inserts into the medial side of the base of the proximal phalanx of the great toe.
• Abductor digiti minimi (seeFig. 21-8).This muscle arises from the lateral process of the calcaneal tuberosity as well as the plantar aponeurosis and inserts into the lateral side of the base of the proximal phalanx of the little toe.
• Flexor digitorum brevis (seeFig. 21-8).This muscle arises from the medial process of the calcaneal tuberosity, lateral to the abductor hallucis and deep into the central portion of the plantar fascia, and inserts into the middle phalanx of the lateral four toes.

Second Layer

• Flexor digitorum accessorius (quadratus plantae;Fig. 21-8).This muscle arises from the calcaneal tuberosity via two heads. The medial head arises from the medial surface of the calcaneus and the medial border of the long plantar ligament, whereas the lateral head arises from the lateral border of the anterior (plantar) surface of the calcaneus and the lateral border of the long plantar ligament. The muscle terminates in tendinous slips, joining the long flexor tendons to the second, third, fourth, and occasionally fifth toes.
• Lumbricales.There are four lumbricales (see Fig. 21-8), all of which arise from the tendon of the flexor digitorum longus. The first arises from the medial side of the tendon of the second toe, the second from adjacent sides of the tendons for the second and third toes, the third from adjacent sides of the tendons for the third and fourth toes, and the fourth from adjacent sides of tendons for the fourth and fifth toes. They insert with the tendons of the extensor digitorum longus and interossei into the bases of the terminal phalanges of the four lateral toes. The function of the lumbricales is to flex the MTP joint and extend the proximal IP (PIP) joint.

Third Layer

• Flexor hallucis brevis (Fig. 21-8).This muscle arises from the medial part of the anterior (plantar) surface of the cuboid bone, the adjacent portion of the lateral cuneiform, and the posterior tibialis tendon and inserts on the medial and lateral side of the proximal phalanx of the great toe.
• Flexor digiti minimi (seeFig. 21-8).This muscle arises from the sheath of the fibularis (peroneus) longus, the base of the fifth metatarsal bone, and inserts into the lateral side of the base of the proximal phalanx of the little toe.
• Adductor hallucis (seeFig. 21-8).This muscle arises via two heads: an oblique and a transverse head. The oblique head arises from the bases of the second, third, and fourth metatarsal bones and the sheath of the fibularis (peroneus) longus. The transverse head arises from the joint capsules of the second, third, fourth, and fifth MTP heads and the deep transverse metatarsal ligament. The adductor hallucis inserts on the lateral side of the base of the proximal phalanx of the great toe.

Fourth Layer

• Posterior (dorsal) interossei.The four posterior (dorsal) interossei are bipennate, and they arise from adjacent sides of the metatarsal bones. The first inserts into the medial side of the proximal phalanx of the second toe. The second inserts into the lateral side of the proximal phalanx of the second toe. The third inserts into the lateral side of the proximal phalanx of the third toe, and the fourth inserts into the lateral side of the proximal phalanx of the fourth toe. The posterior (dorsal) interossei function to abduct the second, third, and fourth toes from an axis through the second metatarsal ray.
• Anterior (plantar) interossei (Fig. 21-8).The three anterior (plantar) interossei are unipennate and arise from the bases and medial sides of the third, fourth, and fifth metatarsal bones. They insert into the medial sides of the bases of the proximal phalanges of the third, fourth, and fifth toes. The anterior (plantar) interossei function to adduct the lateral three toes.

The posterior (dorsal) intrinsic muscles of the foot are the extensor hallucis brevis (EHB) and extensor digitorum brevis (EDB). The EHB inserts into the base of the proximal phalanx of the great toe, whereas the EDB inserts into the base of the second, third, and fourth proximal phalanges. Both of these muscles are innervated by the lateral terminal branch of the deep fibular (peroneal) nerve.

The arches of the foot support the foot by three mechanisms 80

• The osseous relationship of the tarsal and metatarsal bones.
• Ligamentous support from the plantar aponeurosis and anterior (plantar) ligaments.
• Muscle support. 81There are three main arches: the medial longitudinal, the lateral longitudinal, and the transverse arches.
• The medial longitudinal archplays an important role in foot function during weight-bearing activities. The arch comprises the calcaneus, talus, navicular, three cuneiforms, and the three medial metatarsals (including the two sesamoids). Although some of the integrity of the arch depends on the bony architecture, support is also provided by the ligaments and muscles, including the anterior (plantar) calcaneonavicular (spring) ligament, the plantar fascia, the tibialis posterior, fibularis (peroneus) longus, flexor digitorum longus, FHL, and fibularis (peroneus) longus. 78, 82, 83The soleus and gastrocnemius muscle group has also been noted to have an effect on the arch and can flatten it with adaptive shortening. 78Not only is the arch a major source of frontal plane motion of the foot, but it also is a major load-bearing structure. 84Analysis of the medial longitudinal arch has long been used by clinicians to make determinations about foot abnormalities, with a high arch indicating a supinated foot and a low or collapsed arch being associated with a pronated or flatfoot, respectively. 85Studies have found a higher incidence of stress fractures, plantar heel pain, metatarsalgia, and lower extremity injuries, including knee strains and iliotibial band syndrome, in individuals with high arches, compared with those who have low arches. 86– 88This difference has always been attributed to the decreased shock-absorbing ability of the higher-arched foot, 89although one study reported that arch height does not affect shock absorption. 90
• The lateral longitudinal arch, which is more stable and less mobile than the medial longitudinal arch, consists of the calcaneus, cuboid, and fourth and fifth metatarsals. The superior and deep longitudinal plantar ligament supports the calcaneocuboid and cubometatarsal joints, together with the fibularis (peroneus) brevis, longus, and tertius, and the abductor digiti minimi and FDB muscles. 91
• The transverse archforms the convexity of the posterior aspect of the foot and consists of metatarsal heads one through five, including the sesamoids (arch I); cuneiforms one through three and the cuboid (arch II); and the navicular and cuboid (arch III). The adductor hallucis, fibularis (peroneus) longus, posterior tibialis, and anterior tibialis all add dynamic support to this arch.

The nail plate is composed of keratinized squamous cells, bordered by proximal and lateral nail folds. 92The hyponychium lies between the distal portion of the nail bed and the distal nail fold and marks the transition to normal toe epidermis. 92Fingernail plates grow on average at a rate of 3 mm per month, and toenail plates grow at one-half to one-third that rate. 92

The saphenous nerve, the largest cutaneous branch of the femoral nerve, provides cutaneous distribution to the medial aspect of the foot. Branches of the sciatic nerve provide the sensory and motor innervation for the foot and leg (see Chap. 3). The branches are the common fibular (peroneal) and tibial nerves. The common fibular (peroneal) nerve, in turn, divides into the superficial fibular (peroneal) and deep fibular (peroneal) nerves ( Fig. 21-9). The tibial nerve divides into the sural, medial calcaneal, medial anterior (plantar), and lateral anterior (plantar) nerves. 92

Two branches of the popliteal artery, the anterior tibial artery and the posterior tibial artery, form the main blood supply to the foot ( Fig. 21-9).

Anterior Tibial Artery

The anterior tibial artery supplies the anterior compartment of the leg and enters the posterior aspect of the foot under the superior and inferior retinacula as the posterior (dorsal) pedis artery. The posterior (dorsal) pedis artery gives rise to the arcuate artery and the first posterior (dorsal) and anterior (plantar) metatarsal artery, which serve the posterior aspect of the foot and the digits.

Posterior Tibial Artery

The posterior tibial artery, which supplies the posterior and lateral compartments and 75% of the blood to the foot, enters the foot after traveling around the medial malleoli. At this point, the artery divides into the medial and lateral anterior (plantar) arteries, which serve the anterior (plantar) aspect of the foot. A main branch of the posterior tibial artery, the fibular (peroneal) artery, supplies the lateral compartment as well as many hindfoot structures.

Terminology

Motions of the leg, foot, and ankle consist of single- and multiplane movements. The single-plane motions include the following:

• The frontal plane motions of inversion and eversion.Eversion is a frontal plane motion of the foot about an anteroposterior axis, in which the medial aspect of the sole of the foot moves in an anterior (plantar) direction ( Fig. 21-10). Inversion is a frontal plane motion of the foot about an anteroposterior axis, in which the lateral aspect of the sole of the foot moves in an anterior (plantar) direction ( Fig. 21-10).
• The sagittal plane motions of dorsiflexion and plantar flexion.These movements at the ankle and at the midtarsal jointoccur in the sagittal plane about a M-L axis. 93Plantar flexion is a movement of the foot downward toward the ground, and dorsiflexion is a movement of the foot upward toward the tibia.
• The horizontal plane motions of adduction and abduction.These motions of the forefoot occur in the horizontal plane about a superoinferior axis. 93Abduction moves the forefoot laterally, whereas adduction moves the forefoot medially.

A triplane motion describes a movement about an obliquely oriented axis through all three body planes. Triplanar motions occur at the talocrural, subtalar, and midtarsal joints and at the first and fifth rays. 94Pronation and supination are examples of triplanar motions. The three body plane motions in pronation are abduction in the transverse plane, dorsiflexion in the sagittal plane, and eversion in the frontal plane ( Fig. 21-11). 94The three body plane motions in supination are adduction, plantar flexion, and inversion ( Fig. 21-12). 94In pronation, the forefoot is rotated in such a manner so that the big toe moves downward and little toe moves upward, whereas in supination, the reverse occurs.

Distal Tibiofibular Joint

Although the two tibiofibular joints (proximal and distal) are described as individual articulations, they function as a pair. The movements that occur at these joints are primarily a result of the ankle's influence.

• Supination of the foot produces a distal and posterior glide of the head of the fibula.
• Pronation produces a proximal and anterior glide with an external rotation of the fibula.
• Plantar flexion of the foot produces a distal glide with a slight medial rotation of the fibula.
• Dorsiflexion of the ankle yields a proximal glide. The fibula rotates externally around its longitudinal axis.

During these movements, however, it is the tibia that performs the greatest amount of movement, as it rotates around the fibula. This is probably a consequence of more body weight falling through the larger bone. During ipsilateral rotation, both the tibia and the fibula rotate laterally, but in relative terms, the tibia moves more laterally than the fibula, causing a relative anterior and superior glide of the fibular head on the tibia at the superior joint. During contralateral rotation, the tibia rotates more medially, producing a relative posterior and inferior fibular glide at the joint.

The ligaments of the distal tibiofibular joint are more commonly injured than the ATFL. 95Injuries to the ankle syndesmosis most often occur as a result of forced external rotation of the foot or during internal rotation of the tibia on a planted foot. 17Hyperdorsiflexion may also be a contributing mechanism. 96

The capsular pattern of this joint is probably pain with weight-bearing dorsiflexion of the ankle, as this produces the greatest ligamentous tension ( Table 21-1). For the same reason, the close-packed position is considered as weight-bearing dorsiflexion of the ankle.

Talocrural Joint

The talocrural joint is classified as a synovial hinge or modified sellar joint. There is general agreement that motion between the tibia and the foot is a complex combination of talocrural and subtalar joint motion, which is limited by the shape of the articulations and soft tissue interaction. 22Stability for this joint in weight-bearing is provided by the articular surfaces, while in non–weight-bearing, the ligaments appear to provide the majority of stability. 24

The primary motions at this joint are dorsiflexion and plantar flexion ( Fig. 21-10), with a total range of 70–80 degrees. The maximum amount of dorsiflexion necessary at the talocrural joint during human gait is approximately 10 degrees of the normally available 20 degrees, 94, 97, 98and occurs during the stance phase, just prior to heel rise. 99The orientation of the talocrural joint axis, which is oriented on average 20–30 degrees posterior to the frontal plane as it passes posteriorly from the medial malleolus to the lateral malleolus, 23, 83, 100can be estimated clinically as a line that passes inferiorly from the medial malleolus to the lateral malleolus (with a mean orientation of 10 degrees to the horizontal plane), with the adult distal leg being oriented vertically. 83, 100, 101Although the majority of talocrural motion occurs in the sagittal plane, an significant amount of horizontal motion occurs in the horizontal plane, especially during internal rotation of the tibia or pronation of the foot. 83, 100

Because of the fit of the saddle-shaped talus within the mortise, the talus is able to produce a slight separation of the tibial and fibula malleoli during the extremes of dorsiflexion and plantar flexion. 102In addition, because of this fit, the tibia follows the talus during weight-bearing so that the talocrural joint externally rotates with supination and internally rotates with pronation. 103Conversely, the tibia internally rotates during pronation and externally rotates during supination. 104

Theoretically, the capsular pattern of the ankle joint is more restriction of plantar flexion than dorsiflexion, although clinically this appears to be reversed ( Table 21-1). The close-packed position is weight-bearing dorsiflexion, whereas the open-packed position is midway between supination and pronation.

Subtalar Joint

The subtalar (talocalcaneal) joint functions to provide inversion and eversion of the hindfoot—approximately 50% of apparent ankle inversion observed actually comes from the subtalar joint. 105The axis of motion for the subtalar joint, which is approximately 45 degrees from horizontal and 20 degrees medial to the midsagittal plane, 21, 36, 83moves during subtalar joint motion, 106– 108which allows the subtalar joint to produce a triplanar motions of pronation/supination. This motion has been compared with a ship on the sea or an oblique mitered hinge. 109The various components of the triplanar motion at this joint vary according to whether the joint is weight-bearing or non–weight-bearing. 110

• During weight-bearing (close chain) activities, pronation involves a combination of calcaneal eversion, adduction, and plantar flexion of the talus and internal rotation of the tibia, whereas supination involves a combination of calcaneal inversion, abduction and dorsiflexion of the talus and external rotation of the tibia. 111
• During non–weight-bearing (open chain) activities, pronation involves a combination of calcaneal eversion and abduction and dorsiflexion of the talus (see Fig. 21-11), whereas supination involves a combination of calcaneal inversion and adduction and plantar flexion of the talus (see Fig. 21-12). 111

The subtalar joint controls supination and pronation in close conjunction with the transverse tarsal joints of the midfoot. Subtalar joint supination and pronation are measured clinically by the amount of calcaneal or hindfoot inversion and eversion. In normal individuals, there is an inversion to eversion ratio of 2:3 to 1:3, which amounts to an average of approximately 20 degrees of inversion and 10 degrees of eversion. 20, 83, 94, 109For normal gait, a minimum of 4–6 degrees of eversion and 8–12 degrees of inversion are required. 108

During normal gait, the foot needs to pronate and supinate 6–8 degrees from the neutral position. 112If the foot pronates excessively, a compensatory internal rotation of the tibia may occur. This produces an increased amount of rotatory stress and dynamic abduction moment at the knee, which has to be absorbed through the peripatellar soft tissues at the knee joint. 113– 116These stresses can force the patella to displace laterally and may result in patellofemoral dysfunction. 3, 117In addition, a change in the position of the talus can affect the functional leg length. Subtalar supination may cause the leg to lengthen, while subtalar pronation shortens the leg. Thus, the mid-position of the subtalar joint, subtalar joint neutral, is considered the range at which the subtalar joint should act to prevent dysfunction. The subtalar joint neutral position is actually a measurement of the angle between a line that bisects the distal third of the lower leg and a line that bisects the calcaneus. 118The bisection of the calcaneus represents the position of the anterior (plantar) condyles, because the calcaneus is almost perpendicular to the condyles. The angle between the bisections should be 0 degree in the normal foot but is actually 2–3 degrees of varus (inverted in most subjects). 119

Stability for the subtalar joint is provided by the CFL, the cervical ligament, the interosseous ligament, the lateral talocalcaneal ligament, the fibulotalocalcaneal ligament (ligament of Rouviere), and the extensor retinaculum. 120

The capsular pattern of this joint varies. In chronic arthritic conditions, there is an increasing limitation of inversion, but with traumatic arthritis, eversion appears most limited clinically. The close-packed position for this joint is full inversion, whereas the open-packed position is inversion/plantar flexion ( Table 21-1).

Midtarsal (Transverse Tarsal) Joint Complex

The function of the midtarsal joint complex is to provide the foot with an additional mechanism for raising and lowering the arch and to absorb some of the horizontal plane tibial motion that is transmitted to the foot during stance. 103, 121Motions around the two axes at the midtarsal joint involve 80

• a rotational motion about a longitudinal axis into inversion and eversion, which can be observed in the elevation and depression of the medial arch of the foot during the stance phase of gait, 20, 21
• an oblique axis, producing the near sagittal motions of forefoot dorsiflexion and abduction, and forefoot plantar flexion and adduction. 20

Both axes are dependent on the position of the subtalar joint. 20, 108, 121When the subtalar joint is pronated, the two sets of axes are parallel to one another, allowing for the maximum amount of motion at the midtarsal joint. When the subtalar joint is supinated, the two sets of axes are in opposition, allowing little motion to occur, thereby enhancing stability.

During gait, the midtarsal joint has following two functions 80:

• To permit adaptation of the foot to uneven terrain in the early stance
• To provide a stable foot during terminal stance

Theoretically, as a modified ovoid, the joint complex can sublux into dorsiflexion/plantar flexion, abduction/adduction, with or without rotation. In practice, the most commonly found subluxations may be considered as inversion/dorsiflexion or eversion/plantar flexion lesions. 46The capsular pattern of the midtarsal joint complex is a limitation of dorsiflexion, plantar flexion, adduction, and internal rotation ( Table 21-1). The close-packed position for the midtarsal joint is supination ( Table 21-1). The open-packed position is midway between the extremes of ROM.

Cuneonavicular Joint

The cuneonavicular joint has one to two degrees of freedom: plantar/dorsiflexion, inversion/eversion. The capsular pattern of this joint is a limitation of dorsiflexion, plantar flexion, adduction, and internal rotation. The close-packed position is supination. The open-packed position is considered to be midway between the extremes of ROM ( Table 21-1).

Intercuneiform and Cuneocuboid Joints

Due to their very plane curvature, these joints have only one degree of freedom: inversion/eversion. The close-packed position for these joints is supination. The open-packed position is considered to be midway between extremes of ROM ( Table 21-1).

Cubometatarsal Joint

The capsular pattern of this joint is a limitation of dorsiflexion, plantar flexion, adduction, and internal rotation. The close-packed position is pronation. The open-packed position is considered to be midway between extremes of ROM ( Table 21-1).

Cubonavicular Joint

The close-packed position for this joint is supination. The open-packed position is midway between extremes of ROM ( Table 21-1).

Intermetatarsal Joints

The close-packed position for these joints is supination. The open-packed position is midway between extremes of ROM ( Table 21-1).

MTP Joints

The MTP joints have two degrees of freedom: flexion/extension and abduction/adduction. ROM of these joints is variable, ranging from 40 to 100 degrees dorsiflexion (with a mean of 84 degrees), 3–43 degrees (mean, 23 degrees) plantar flexion, and 5–20 degrees varus and valgus. 122The closed-packed position for the MTP joints is full extension. The capsular pattern for these joints is variable, with more limitation of extension than flexion. The open-packed position is 10 degrees of extension.

First MTP Joint

The function of the great toe is to provide for normal propulsion during gait and to provide stability to the medial aspect of the foot. Normal alignment of the first MTP joint varies between 5 degrees varus and 15 degrees valgus. 123The most important motion at the first MTP is dorsiflexion. During normal gait, the first MTP joint dorsiflexes approximately 60 degrees. During sprinting (running sports), squatting (football and baseball), and relevé (in dance), greater than 90 degrees of dorsiflexion is necessary.

The first MTP is characterized by having a remarkable discrepancy between active and passive motion. The first ray of the foot consists of the first metatarsal and the first (medial) cuneiform bone. These two bones act as a functional unit, playing an important role in providing structural integrity to the foot during weight-bearing activities. 83Three extrinsic muscles of the foot insert at the base of the first ray: the anterior tibialis, posterior tibialis, and fibularis (peroneus) longus. The need for clinical assessment of the posterior (dorsal) mobility of the first ray is based on its functional role during weight-bearing activities. Any disruption to its normal motion (hypo- or hypermobility) reduces the ability of the first ray to adequately stabilize the medial column of the foot and the longitudinal arch, increasing the potential for injury to the head of the first metacarpal. 124

IP Joints

Each of the IP joints has one degree of freedom: flexion/extension. The capsular pattern is more limitation of flexion than of extension. The close-packed position is full extension ( Table 21-1). The open-packed position is slight flexion.

The examination is used to identify static and dynamic, and structural or mechanical foot abnormalities. The clinical diagnosis is based on an assessment of the changes in joint mobility and tissue changes at the foot and ankle and the effect these have on the function of the foot and ankle and the remainder of the lower kinetic chain.

The exact form of the examination is very much dependent on the acuteness of the condition. For example, weight-bearing tests cannot be done if the patient cannot bear weight, and most stress tests will prove impossible if the joints cannot be taken to their full range. In these cases, the clinician must rely heavily on the history.

The primary purposes of the history are to do the following:

• Determine the patient's chief complaint.
• Determine the mechanism of injury, if any. Information about the mechanism of injury should include when, where, how, and if an injury occurred. Details about the mechanism of injury allow the clinician to infer the pathologic status and structures involved, although it must be remembered that the patient's recollection of the mechanism involved frequently does not necessarily correspond to the structures damaged. 16, 125Most ankle sprains occur when the foot is plantar flexed, inverted, and adducted ( Table 21-6). This same mechanism can also lead to a malleolar or talar dome fracture. A history involving sudden changes in training patterns may indicate an overuse injury. A dorsiflexion injury with associated snapping and pain on the lateral aspect of the ankle that rapidly diminishes may indicate a tear of the fibular (peroneal) retinaculum. 126If there is no traumatic event, the clinician must determine if there has been a change in exercise or activity intensity (e.g., increased mileage with runners), training surface, or changes in body weight or shoe wear (causal agents). 16, 125In addition, the clinician must determine whether the symptoms vary with activity, type of terrain, or changes in position. Complaints of cramping may accompany muscular fatigue or intermittent claudication from arterial insufficiency. Plantar heel pain associated with plantar fasciitis is typically associated with an insidious onset. Achilles tendinitis is an overuse injury associated with an insidious onset of posterior calcaneal pain. Increased symptoms when walking or running on uneven terrain as compared with an even terrain may suggest ankle instability. Increased symptoms when walking or running on hard surfaces as compared with a softer surface may suggest a lack of shock absorbency of the foot or shoe. Pain that is related to a certain time of day may indicate an activity-related problem or a condition such as plantar heel pain if the pain is felt when first bearing weight in the morning.
• Determine the patient's occupation, if any. The impact of the injury on the patient's personal life, work, and athletic demands will largely direct the early intervention. 16, 125
  • If painless ambulation is essential, then rigid immobilization (i.e., a cast) may be appropriate.
  • If rapid return to sports competition is of paramount importance, functional immobilization is preferred.
• Determine the location and severity of the condition. Most often, the patient can point to the location of the pain. The site and severity of the pain can be measured using a body diagram and visual analog scale, respectively. The distribution of pain is important, and the clinician should determine whether the pattern is referred, associated with a structure, related to a dermatome or peripheral nerve, or systemic in nature. 127A stress fracture or tendinitis typically has a localized site of pain, whereas diffuse pain is associated with compartment syndromes.
• Determine which activities and positions aggravate the symptoms. Information should be gleaned about whether activities aggravate the symptoms and if so, which. For example, pain with forced dorsiflexion and eversion and with squatting activities may suggest ankle instability. Pain after activity suggests an overuse or chronic injury. Pain during an activity suggests stress on the injured structure.
• Ascertain the area, nature, and behavior of the symptoms. 128Information about the time of injury, the time of the onset of swelling, and its location are important. The patient may report hearing a “snap,” “crack,” or “pop” at the time of injury, which could indicate a ligamentous injury or a fracture. The patient may report that their ankle felt weak and/or unstable at the time of the initial trauma or sometime thereafter. An inability to bear weight or the presence of severe pain and rapid swelling indicates a serious injury such as a capsular tear, fracture, or grade III ligament sprain. 129– 132
• Help determine the specific structure at fault. 133
• Detect systemic conditions (e.g., collagen disease, neuropathy, radiculopathy, and vascular problems) or the presence of serious pathology.

In addition, questions regarding previous ankle injury, goals of the patient regarding functional goals, level and intensity of sports involvement, and past medical history are important to help the clinician individualize the intervention to the patient.

As symptoms can be referred distally to the leg, foot, and ankle from a host of other joints and conditions, the clinician must be able to differentially diagnose from the presenting signs and symptoms (see Chap. 5). The cause of the referred symptoms may be neurologic or systemic in origin. If a disorder involving a specific nerve root (L4, L5, S1, or S2) is suspected, the necessary sensory, motor, and reflex testing should be performed. Peripheral nerve injuries may also occur in this region and often go unrecognized. These include Morton's neuroma and entrapment of the tibial nerve or its branches, the deep fibular (peroneal) nerve, superficial fibular (peroneal) nerve, and sural and saphenous nerves. 134

Systemic problems that may involve the leg, foot, and ankle include diabetes mellitus (peripheral neuropathy), osteomyelitis, gout and pseudogout, sickle cell disease, complex regional pain syndrome, peripheral vascular disease, and rheumatoid arthritis (refer to Chap. 5). A systemic problem such as rheumatoid arthritis may be associated with other signs and symptoms, including other joint pain, although the other joint pain may also be the result of overcompensation in the rest of the kinetic chain.

Warning signs at the ankle and foot that should alert the clinician to a more insidious condition include:

• immediate and continuous inability to bear weight, which may indicate a fracture;
• nocturnal pain, which may indicate a malignancy, hemarthrosis, fracture, or infection;
• gross pain during ankle valgus and tenderness with pressure on the distal fibula, which may indicate a fractured fibula;
• pain and weakness during resisted eversion, which may indicate fracture of the fifth metatarsal bases;
• calf pain and/or tenderness, swelling with pitting edema, increased skin temperature, superficial venous dilatation, or cyanosis, which may indicate the presence of a deep vein thrombosis (DVT), requiring immediate medical attention (see Chap. 5);
• feelings of warmth or coldness in the foot. An abnormally warm foot can indicate local inflammation but can also originate from a tumor in the pelvic or lumbar region. 135An abnormally cold foot usually indicates a vascular problem. 135

Observation

Observation of the lower extremity is extensive. It is extremely important to observe the entire kinetic chain when assessing the leg, foot, and ankle. Weight-bearing and non–weight-bearing postures of the foot are compared.

Observing the patient while they move from sitting to standing and walk to the treatment area gives the clinician a sense of the patient's functional ability in weight-bearing and provides the first opportunity for gait analysis. 101An important part of the examination of the foot and ankle is the gait assessment (see Chap. 6). During gait, the transverse and longitudinal arches can be grossly assessed—the lateral longitudinal arch bears the body weight in the early stance, whereas the medial longitudinal arch provides support in the mid- and late-stance phase of gait. 136The foot should touch the ground, the heel first and the heel should begin to rise at approximately 35% of the gait cycle. 136Early heel rise may occur due to tightness of the gastrocnemius–soleus complex, whereas late heel rise may be secondary to weakness of the calf musculature. 136Normally, the foot pronates during the early stance phase, but the foot should not remain pronated during heel rise and toe off. 136

The following are assessed with the patient standing:

• Shoulder and pelvic heights (see Chaps. 16and 29).
• Spinal curvature (see Chap. 27).
• Pelvic rotation (see Chap. 29).
• The degree of hip rotation.In the femur, anteversion and retroversion angles should be noted (refer to Chap. 19). Excessive internal rotation of the hip toward the opposite hip (anteversion) may result in a flattening of the medial longitudinal arch and toeing-in/internal torsion of the tibia (pigeon toes). Excessive external rotation of the hip away from the opposite hip (retroversion) may result in an elevation of the medial longitudinal arch.
• The degree of knee flexion or hyperextension.A genu recurvatum (hyperextension) places the talocrural joint in more plantar flexion than normal and can often be a compensatory mechanism in the longer limb of individuals who have a leg-length inequality; see Chap. 29. 139An increase in knee flexion accomplishes the same compensation for a leg-length inequality. 139
• The degree of varus and valgus of the knee and tibia.Excessive tibia varum, genu varus, or forefoot varus can increase the frontal angle of the talocrural joint, which promotes excessive weight-bearing on the lateral aspect of the foot unless compensatory pronation is available within the foot to bring the medial aspect of the foot to the support surface. 139Tibia varum refers to the frontal plane position of the distal one-third of the leg, as it relates to the supporting surface. 107
• Rotational components of the tibia.Tibial torsion is assessed with the patient in sitting, with their feet hanging over the end of the bed so that their knees are in approximately 90 degrees of flexion. 101The thumb of one hand is placed over the apex of one malleolus, and the index finger of the same hand is placed over the apex of the other malleolus. A qualitative estimate of the direction and magnitude of tibial torsion can be made by envisioning a line that passes through the malleoli and estimating its orientation to the frontal plane of the proximal tibia. 139Alternatively, tibial torsion can be measured with the patient in prone with the knee flexed to 90 degrees and the subtalar joint positioned and stabilized in subtalar neutral.*

Once the subtalar neutral position has been established, a line is drawn on the sole of the foot parallel to the length of the femur. A second line is drawn in line with the foot. The angle between these lines is the tibial torsion angle. 64There is normally an angle of 12–18 degrees to the frontal plane. 140Tibial torsion is generally less in children. A position of relative internal rotation of the tibia produces an increase in rigidity to the subtalar joint prior to midstance, due to premature stabilization of the longitudinal arch of the foot. 141Excessive external rotation of the tibia places an increased strain along the longitudinal arch, as well as the first MTP joint. 141

• Rearfoot to leg orientation.This can be an indicator of weight-bearing subtalar position. It is assessed by measuring the acute angle formed between a line representing the posterior aspect of the distal third of the leg, and a line approximately 1-cm distal to the first mark, representing the midline of the posterior aspect of the calcaneus (see Fig. 21-13). 139The angle is assessed as the patient shifts weight on the lower extremity to simulate single-limb support. If the lines are parallel or in slight varus (2–8 degrees), the leg–rearfoot orientation is considered normal. 142Movement of the rearfoot into eversion (rearfoot valgus) during this maneuver is indicative of subtalar pronation. 94Pronation of the foot is manifested by eversion of the heel, abduction of the forefoot, a decrease in the medial longitudinal arch, internal rotation of the leg in relation to the foot, and dorsiflexion of the subtalar and midtarsal joints. If the heel is in too much valgus, the forefoot is excessively abducted, or there is excessive external rotation of the tibia, more toes can be seen on the affected side than the normal side when viewing the leg from behind (“too-many-toes sign”). 42If the patient is asked to raise up on the toes, the calcaneus should be observed to move into a position of inversion. An inability of the calcaneus to invert with this maneuver could indicate the presence of an abnormality within the subtalar joint mechanism or a weakness of the posterior tibialis. 42, 141
• The weight-bearing foot.The following are major components of the normal weight-bearing foot: 119, 143
  • Both planar condyles of the calcaneus are on the floor surface. An imaginary plane representing the ground surface is applied to the anterior (plantar) surface of the calcaneus. The metatarsal heads should rest upon this plane. If the plane of the metatarsal heads is perpendicular to the bisection of the calcaneus, the forefoot-to-rearfoot relationship is normal, or neutral.
  • The “normal” foot should demonstrate 6–8 degrees of calcaneal eversion during gait. The foot should pronate initially, just after initial contact (see Chap. 6).
  • All of the metatarsal heads lie in one plane, which is in the same plane as the anterior (plantar) condyles of the calcaneus 94
  • The ball of the foot is level with the plantar surface of the heel.
  • A normal forefoot-to-rearfoot relationship (see later).
  • The orientation of the distal third of the lower leg should be vertical, to position the foot properly for the stance phase.
  • The midtarsal joint is maximally pronated, while the subtalar joint, MTP, and IP joints are in neutral.
  • The presence of a well-formed static medial arch should be noted, as well as its dynamic formation with heel raising.
• Forefoot-to-rearfoot relationship.Goniometric measurement of forefoot position relative to the rearfoot is a routine procedure used by rehabilitation specialists. This measurement is also frequently made by visual estimation. Neutral alignment of the forefoot relative to the rearfoot is present when a line representing the anterior (plantar) aspect of the metatarsal heads is perpendicular to the line bisecting the rearfoot. The forefoot-to-rearfoot angle is approximately 10–12 degrees. 119, 143Forefoot varus is the term used to describe inversion of the forefoot away from this neutral position, while forefoot valgus describes an everted forefoot position. 139The relationship can be assessed with the patient positioned in prone with their knee extended and their feet over the end of the table. The subtalar neutral position is located using the method described previously. Slight pressure is applied to the metatarsal heads while maintaining subtalar neutral. This will determine the relationship of the forefoot to rearfoot, and both of these to the bisection of the lower leg. A varus or valgus tilt of the forefoot in relation to the hindfoot becomes significant when the first metatarsal is in a plantar flexed position, as this positions the hindfoot into an inverted position during weight-bearing. 141Somers et al. examined the reliability of goniometric and visual estimation of forefoot position measurements when experienced and inexperienced testers performed the evaluation. Two clinicians (≥ 10 years' experience) and two physical therapy students were recruited as testers. Ten subjects (20–31 years old), free from pathology, were measured. Each foot was evaluated twice with the goniometer and twice with visual estimation by each tester. Intraclass correlation coefficient (ICC) and coefficients of variation method error were used as estimates of reliability. There was no dramatic difference in the intratester or intertester reliability between experienced and inexperienced testers, regardless of the evaluation used. Estimates of intratester reliability (ICC 2,1), when using the goniometer, ranged from 0.08 to 0.78 for the experienced clinicians and from 0.16 to 0.65 for the inexperienced clinicians. When using visual estimation, ICC (2,1) values ranged from 0.51 to 0.76 for the experienced clinicians and 0.53 to 0.57 for the inexperienced clinicians. The estimate of intertester reliability [ICC (2,2)] for the goniometer was 0.38 for the experienced clinicians and 0.42 for the inexperienced clinicians. When using visual estimation, ICC (2,2) values were 0.81 for the experienced clinicians and 0.72 for the inexperienced clinicians. Although experience does not appear to influence forefoot position measurements, of the two evaluation techniques, visual estimation may be the more reliable.
• Foot deviations in weight-bearing.These include pes planus (low inclined subtalar joint axis), pes cavus (high inclined subtalar joint axis), talipes equinus (plantar flexed foot), talipes equinovarus (supinated foot), and hallux valgus. 101
• Degree of foot pronation or supination in non–weight-bearing.The patient lies in the prone position, with the foot over the edge of the table. The clinician holds the foot over the fourth and fifth metatarsal heads with one hand. Both sides of the talus are palpated on the posterior aspect of the foot using the thumb and index finger of the other hand. The clinician then passively dorsiflexes the foot until a resistance is felt. At this point, and while maintaining the dorsiflexed position, the clinician moves the foot back and forth through the arc of supination and pronation. During supination, the talus should be felt to bulge laterally, while during pronation, the talus should be felt to bulge medially. Supination at the subtalar joint occurs in association with 20 degrees of calcaneal inversion, while pronation occurs in association with 10 degrees of calcaneal inversion.
• Degree of toe-out.The normal foot in relaxed standing adopts a slight toe-out position of approximately 12–18 degrees from the sagittal axis of the body (Fick angle). 134
• Forefoot equinus.To assess for forefoot equinus, the clinician stabilizes the rearfoot with one hand and applies pressure on the entire forefoot via pressure across the metatarsal heads, into dorsiflexion. If the plantar declination of the lateral structures cannot be reduced so that the plantar flexed attitude is no longer visible, a positive identification of forefoot equinus can be made. 143
• Presence of a talar bulge.The patient is positioned in standing, and the clinician observes to see whether the talar head bulges excessively on the medial side of the midfoot, indicating excessive subtalar joint pronation in weight-bearing. Adaptive shortening of the gastrocnemius/soleus group is indicated with a prominence of the soleus, particularly on the medial side of the teno-calcaneum.

Other areas that should be examined include the following:

• Condition of the nails.When examining the nails a systematic approach is used, involving an inspection of the shape, contour, and color of the nails. The clinician should observe for the presence of subungual hematomas, subungual exostosis, onychocryptosis, onychia, onychauxis, onychomycosis, paronychia, tinea pedis, or blisters.
• Toe deformities.Contractions of the capsule of the IP or MTP joints of the toes in association with tendon shortening may produce a series of deformities, ranging from hammer toe to mallet toe to claw toe. Hammer toeusually involves a flexion contracture of the anterior (plantar) surface of the PIP, with a mild associated extension contracture of the MTP joint. Mallet toeresults from a flexion deformity of the distal interphalangeal joint (DIP) with plantar contracture. Often a corn or callus is present on the posterior aspect of the affected joint. Corns are similar to calluses but have a central nidus. Claw toedeformity is a more advanced contracture of capsules and intrinsic musculature, which may also be associated with pes cavus and neurologic or primary muscle pathology to the lumbrical and interosseous muscles. The claw toe results in hyperextension of the MTP joints and flexion of the PIP and DIP joints.
• Functional hallux limitus.Clinically, the presence of functional hallux limitus, an inability of the first MTP joint to extend, can be determined by assessing the ROM available at the first MTP joint, while the first ray is prevented from plantar flexing. The patient is positioned in standing, the feet shoulder-width apart. The patient is asked to actively raise the great toe off the floor, while keeping the remaining toes and foot on the ground. The amount of hallux extension is measured; less than 10 degrees is considered limited. 144This test has been found to have a sensitivity of 0.72 and a specificity of 0.66. 144
• The leg, foot, and ankle are examined for the presence of bruising, swelling, or unusual angulation.Ecchymosis may be present, but the blood usually settles along the medial or lateral aspects of the heel. 16, 125The appearance of bluish-black plaques on the posterior and posterolateral aspect of one or both heels in a young distance runner is found in a condition called black-dot heel, which results from a shearing stress or a pinching of the heel between the counter and the sole of the shoe at initial contact during running.

Extracellular fluid pools on the posterior aspect of the foot and around the malleoli after injury or surgery. 101Shortly after a lateral ligament sprain, the swelling is limited to the lateral ankle. Subsequently, the swelling is diffuse, and the localization of tenderness may be difficult. An objective measure of the amount of swelling present can be made using the figure-of-eight method (see “Special Tests”section).

• Callus formation.Calluses provide the clinician with an index as to the degree of shear stresses applied to the foot and clearly outline abnormal weight-bearing areas. 145In adequate amounts calluses provide protection, but in excess they may cause pain. Callus formation under the second and third metatarsal heads could indicate excessive pronation in a flexible foot, or Morton's (interdigital) neuroma (see Chap. 5) if under the second through fourth. A callus under the fifth and sometimes the fourth metatarsal head may indicate an abnormally rigid foot.
• Any evidence of circulatory impairment or vasomotor changes.Brick-red coloring or cyanosis when the leg is dependent is an indication of vascular impairment, especially if the color changes when the leg is elevated. Vasomotor changes include toenail changes, changes in skin texture, abnormal skin moisture or dryness, and loss of hair on the foot. Vasomotor changes may be associated with complex regional pain syndrome (see Chap. 5).
• The type of shoes.High-heeled shoes have been associated with adaptive shortening of the gastrocnemius soleus complex, knee pain, and low-back pain. 50, 146They have also been associated with an increased potential for ankle sprains, hallux valgus, bunions, metatarsalgia, interdigital neuromas, peripheral nerve compression, and stress fractures. 50, 146Shoes with a negative heel may result in hyperextension of the knees.
• The weight-bearing and wear patterns of the shoe.The greatest amount of wear on the sole of the shoe should occur beneath the ball of the foot, in the area corresponding to the first, second, and third MTP joints and slight wear to the lateral side of the heel. Old running shoes belonging to patients who excessively pronate tend to display overcompression of the medial arch of the midsole and extensive wear of the lateral regions of the heel counter and medial forefoot. The upper portion of the shoe should demonstrate a transverse crease at the level of the MTP joints. A stiff first MTP joint can produce a crease line that runs obliquely, from forward and medial to backward and lateral. 147The cup at the rear of the shoe, which is formed by the heel counter ( Fig. 21-34), should be vertical and symmetrical with respect to the shoe and should be of a durable enough material to hold the heel in place. 148A medial inclination of the cup, with bulging of the lateral lip of the counter, indicates a pronated foot. 147A lateral bulge of the heel counter indicates a supinated foot. Scuffing of the shoe might indicate tibialis anterior weakness. 80The shape of the last influences the amount of motion that the shoe permits. 149As the degree of curvature in the last increases, more foot mobility is available.

The non–weight-bearing component of the examination is initiated by having the patient seated on the edge of the bed, feet dangling. The feet should adopt an inverted and plantar flexed position. A mobile or nonstructural flatfoot will take on a more normal configuration in non–weight-bearing, whereas a fixed or structural flatfoot will maintain its planus state. By placing one hand on the patella and the other hand on the tips of the malleoli, the clinician should note approximately 20–30 degrees of external rotation of the ankle in relation to the knee. 141

*The subtalar neutral position refers to the position in which all bones of the subtalar joints and the talocrural joints line up optimally in their open-packed positions—a position of neither pronation nor supination.

Palpation

Careful palpation should be performed around the leg, foot, and ankle to differentiate tenderness of specific ligaments and other structures. Areas of localized swelling and ecchymosis over the ligaments on the medial or lateral aspects of the foot and ankle should be noted.

Posterior Aspect of Foot and Ankle

Achilles Tendon

The Achilles tendon is inspected for contour changes such as swelling, erythema, and thickening. Any gaps or nodules in the tendon and specific sites of pain should be carefully examined. Palpable gaps in the tendon accompanied by an inability to rise up on the toes could indicate a rupture of the tendon.

Calcaneus

At the distal end of the Achilles tendon is the calcaneal tuberosity. The posterior aspect of the calcaneus and surrounding soft tissue is palpated for evidence of exostosis (“pump bump” or Haglund's deformity) and associated swelling (retrocalcaneal bursitis). The inferior medial process of the calcaneus, just distal to the weight-bearing portion of the calcaneus, serves as the attachment of the plantar fascia and is often tender with plantar heel pain.

Anterior and Anteromedial Aspects of the Foot and Ankle

While reading the next section, the reader may find it helpful to remove a shoe and sock and self-palpate.

Great Toe and the Phalanges

Beginning medially, the clinician locates and palpates the great toe and its two phalanges. The first metatarsal bone is more proximal, the head of which should be palpated for tenderness on the lateral aspect (bunion) and inferior aspect (sesamoiditis).

Moving laterally from the phalanges of the great toe, the clinician palpates the phalanges and metatarsal heads of the other four toes.

Tenderness of the second metatarsal head could indicate the presence of Freiberg's disease, an osteochondritis of the second metatarsal head (see Chap. 5). A callus under the second and the third metatarsal head may indicate a fallen metatarsal arch. Palpable tenderness in the region of the third and fourth metatarsal heads could indicate a Morton's neuroma, especially if the characteristic sharp pain between the toes of this condition is relieved by walking barefoot. Tenderness on the lateral aspect of the fifth metatarsal head could indicate the presence of a tailor's bunion.

Cuneiform

The first cuneiform is located at the proximal end of the first metatarsal (see Fig. 21-1) and is palpated for tenderness.

Navicular

The navicular is the most prominent bone on the medial aspect of the foot. The navicular tuberosity can be located by moving proximally from the medial aspect of the first cuneiform (see Fig. 21-1). The talonavicular joint line lies directly proximal to the navicular tuberosity. In addition, the posterior tibialis, which can be made more prominent with resisted plantar flexion, adduction, and supination, can be used as a reference as it inserts on the plantar surface of the navicular (see later). Tenderness of the navicular could indicate the presence of a fracture or osteochondritis of the navicular (Köhler's disease).

Second and Third Cuneiforms

These two bones can be palpated by moving laterally from the first cuneiform (see Fig. 21-1). Tenderness of these bones may indicate a cuneiform fracture.

Posterior (Dorsal) Pedis Pulse

The pulse of the posterior (dorsal) pedis artery, a branch of the anterior tibial artery, can be palpated over the talus, cuneiform bones ( Fig. 21-14), between the first and second cuneiforms, or between the first and second metatarsal bones.

Medial Malleolus

The medial malleolus is palpated for swelling or tenderness. Moving proximally from the anterior aspect of the medial malleolus, the distal aspect of the tibia is palpated. Distal to that is the talus bone. Moving distal from the tibia, the clinician palpates the long extensor tendons, the tibialis anterior, and the superior and inferior extensor retinaculum. The tendon of the tibialis anterior is visible at the level of the medial cuneiform and the base of the first metatarsal bone, especially if the foot is positioned in dorsiflexion and supination.

Talus

The talus can be located by moving from the distal aspect of the medial malleolus along a line joining the navicular tuberosity. It can be more easily located by everting and inverting the foot. Eversion causes the talar head to become more prominent, while inversion causes the head to be less visible.

Sustentaculum Tali

Distal and inferior to the medial malleolus, a shelf-like bony prominence of the calcaneus, the sustentaculum tali, can be palpated. At the posterior aspect of the sustentaculum tali, the talocalcaneal joint line can be palpated.

Posterior Tibialis Tendon

This tendon is palpable at the level of the medial malleolus, especially with the foot held in plantar flexion and supination. Distal and medial to this tendon, the crossing of the flexor digitorum longus and flexor hallucis tendons can be felt.

Posterior Tibial Artery

The posterior tibial artery ( Fig. 21-9) can be located posterior to the medial malleolus and anterior to the Achilles tendon.

Medial (Deltoid) Ligament of the Ankle

The medial (deltoid) ligament of the ankles is very difficult to differentiate, so they are usually palpated as a group on the medial aspect of the ankle (see Fig. 21-4).

Anterior and Anterolateral Aspects of the Foot and Ankle

Tibial Crest

The tibial crest is palpated for tenderness, which may indicate the presence of shin splints. Swelling in this area may indicate the presence of anterior compartment syndrome. The muscles of the lateral (peronei) and anterior compartments (tibialis anterior and the long extensors) are palpated here for swelling or tenderness. Swelling or tenderness of these structures usually indicates inflammation.

Lateral Malleolus

The lateral malleolus is located at the distal aspect of the fibula. Distal to the lateral malleolus is the calcaneus.

Fibularis (Peroneus) Longus

The tendon of the fibularis (peroneus) longus runs superficially behind the lateral malleolus. Resisted pronation and plantar flexion of the foot make the tendon more prominent.

Fibularis (Peroneus) Brevis

The origin for the fibularis (peroneus) brevis is more distal to the fibularis (peroneus) longus and lies deeper. It becomes superficial on the lateral aspect of the foot, at its insertion at the tuberosity of the fifth metatarsal.

Anterior Talofibular Ligament

The ATFL can be palpated two to three finger-breadths anteroinferior to the lateral malleolus (see Fig. 21-5). 129This is usually the area of most extreme tenderness following an inversion sprain. The anterior aspect of the distal tibiofibular syndesmosis may also be tender following this type of sprain.

Calcaneofibular Ligament

The CFL can be palpated one to two finger-breadths inferior to the lateral malleolus (see Fig. 21-5). 129

Posterior Talofibular Ligament

The PTFL can be palpated posteroinferior to the posterior edge of the lateral malleolus (see Fig. 21-5). 129

Sinus Tarsi

The sinus tarsi is visible as a concave space between the lateral tendon of the extensor digitorum longus muscle and the anterior aspect of the lateral malleolus. The origin of the EDB is at the level of this tunnel.

Cuboid

The cuboid bone can be palpated by moving distally approximately one finger-breadth from the sinus tarsi.

Active and Passive Range of Motion

ROM testing is divided into active range of motion (AROM) and passive range of motion (PROM), with overpressure being superimposed at the end of available range to assess the end-feel. AROM tests are used to assess the patient's willingness to move and the presence of movement restriction patterns such as a capsular or noncapsular pattern. The end-feel may provide the clinician with information as to the cause of a motion restriction. The normal ranges of motion and end-feels for the lower leg, ankle, and foot are outlined in Table 21-7. The open- and close-packed positions and capsular patterns for the ankle and foot are outlined in Table 21-1.

General AROM of the foot and ankle in the non–weight-bearing position is assessed first, with painful movements being performed last. The hip and knee joints may also be examined as appropriate. Weight-bearing tests are usually performed after the non–weight-bearing tests.

If the symptoms are experienced during the general tests, then passive, active, and resisted tests of specific structures must be performed. If the general tests are negative, there is probably no immediate need to proceed with a more detailed examination, although this may have to be done if no other region appears to be the cause of the problem.

Although specific motions at the distal tibiofibular joint cannot be produced voluntarily, the function of this joint can be assessed indirectly by asking the patient to twist around both feet in each direction while bearing weight.

Dorsiflexion

The patient lies in the supine position, with the knee slightly flexed and supported by a pillow, while the clinician stands at the foot at the table, facing the patient .

Active dorsiflexion is initially performed with the knee flexed ( Fig. 21-15). Care must be taken to prevent pronation at the subtalar and oblique midtarsal joint during dorsiflexion. The foot is slightly inverted to lock the longitudinal arch. 141Passive overpressure is applied. With the knee flexed to approximately 90 degrees, the length of the soleus muscle is examined. Passive overpressure into dorsiflexion when the knee is flexed assesses the joint motion, as well as the soleus length. The soleus is implicated if pain is produced in this test, especially if resisted plantar flexion is painful or more painful with the knee flexed than with the knee extended. With the knee flexed, 20 degrees of dorsiflexion past the anatomic position (the foot at 90 degrees to the bones of the leg) is found in the normally flexible person. 150The flexibility of the soleus muscle may also be assessed in standing in able-bodied individuals by asking the patient to perform a deep squat or a lunge.

• Squat. If the muscle length is normal, the patient should be able to place the whole foot on the floor, including the heel, while in the full squat position ( Fig. 21-16). If the soleus is short, the heel will not touch the floor.
• Lunge. A standard goniometer is aligned along the lateral aspect of the leg and the floor. The subject steadies themselves and then performs a weight-bearing lunge maneuver ( Fig. 21-17). The angle recorded on the goniometer indicates the range of dorsiflexion under load. If the goniometer is set so that vertical is zero, the arm of the goniometer always aligns to the vertical and the scale rotates to indicate the inclination from the vertical. This angle is then recorded as the ankle dorsiflexion range. This method is considered the most appropriate method of measuring ankle dorsiflexion range, as it reflects the functionally available range for the individual. Bennell et al. 151evaluated the interrater and intrarater reliability of a weight-bearing dorsiflexion lunge using a gravity goniometer in 13 healthy subjects. Two methods were used to assess the dorsiflexion lunge: (1) the distance from the great toe to the wall and (2) the angle between the tibial shaft and the vertical using an inclinometer. The average of three trials was used in data analysis. Intrarater ICCs ranged from 0.97 to 0.98. Interrater ICC values were 0.97 (angle) and 0.99 (distance), indicating excellent reliability for both methods of assessing a DF lunge. 151

To assess the length of the gastrocnemius, the patient is placed in the supine position with the knee extended, and the ankle positioned in subtalar neutral. The patient is then asked to dorsiflex the ankle ( Fig. 21-18). Passive overpressure into dorsiflexion is applied. The normal range is 20 degrees. If the gastrocnemius is shortened, dorsiflexion of the ankle will be reduced as the knee is extended, and increased as the knee is flexed. A muscular end-feel should be felt with the knee extended, and a capsular end-feel should be felt with the knee flexed.

Plantar Flexion

The patient is placed in the supine position, while the clinician stands at the foot of the table, facing the patient . The patient is asked to plantar flex the ankle ( Fig. 21-19). Plantar flexion of the ankle is approximately 30–50 degrees. 94When tested in weight-bearing with the unilateral heel raise, heel inversion should be seen to occur. Failure of the foot to invert may indicate instability of the foot/ankle, posterior tibialis dysfunction, or adaptive shortening. 152

Hindfoot Inversion (Supination) and Hindfoot Eversion (Pronation)

Both hindfoot inversion ( Fig. 21-20) and hindfoot eversion ( Fig. 21-21) are tested by lining up the longitudinal axis of the leg and vertical axis of the calcaneus. Passive motion of hindfoot inversion (supination) is normally 20 degrees. 94The amount of hindfoot eversion (pronation) is normally 10 degrees. 94

Great Toe Motion

The patient is positioned in supine, with the leg being supported by a pillow, while the clinician stands at the foot at the table, facing the patient. Active extension of the great toe is performed and assisted passively without dorsiflexing the first ray. The amount of posterior (dorsal) mobility is usually classified as normal, hypomobile, or hypermobile. Although this method of assessment is common, its reliability and validity have been shown to be poor. 122Extension of the great toe occurs primarily at the MTP joint. Passive extension of the great toe at the MTP joint should demonstrate elevation of the medial longitudinal arch (windlass effect), and external rotation of the tibia. 153Passive MTP joint extension of between 55 and 90 degrees is necessary at terminal stance, 154depending on length of stride, shoe flexibility, and toe-in/toe-out foot placement angle. 139Forty-five degrees of first MTP flexion and 90 degrees of IP joint flexion are considered normal. 141

Strength Testing

Ankle

Gastrocnemius and Plantaris Muscles

Plantar flexion strength can be tested initially in non–weight-bearing ( Fig. 21-22). If no plantar flexion weakness is apparent in non–weight-bearing, a heel raise test is performed in the functional position, standing with the knee extended and the opposite foot off the floor . Technically, one heel raise through full ROM, while standing with support on one leg, scores a 3/5 (fair) with manual muscle testing, with five single-limb heel raises scoring a 4/5 (good) and 10 single-limb heel raises scoring a 5/5 (normal). From a functional viewpoint, a wider range of scoring can sometimes prove more useful. Table 21-8outlines an alternative scoring method.

Soleus Muscle

The soleus muscle produces plantar flexion of the ankle joint, regardless of the position of the knee. To determine the individual functioning of the soleus as a plantar flexor, the knee is flexed to minimize the effect of the gastrocnemius muscle. The soleus is tested in a similar manner to that of the gastrocnemius, except that the patient performs the unilateral heel raise with some degree of knee flexion. Ability to perform 10–15 raises in this fashion is considered normal, five to nine raises graded as fair, one to four raises graded as poor, and zero repetitions graded as nonfunctional. Alternatively, the strength of the soleus can be tested with the patient in prone .

Tibialis Anterior Muscle

The tibialis anterior muscle produces the motion of dorsiflexion and inversion. The knee must remain flexed during the test to allow complete dorsiflexion. The patient's foot is positioned in dorsiflexion and inversion. The leg is stabilized, and resistance is applied to the medial posterior aspect of the forefoot into plantar flexion and eversion ( Fig. 21-23) .

Tibialis Posterior Muscle

The tibialis posterior muscle produces the motion of inversion in a plantar flexed position. The leg is stabilized in the anatomic position, with the ankle in slight plantar flexion. Resistance is applied to the medial border of the forefoot into eversion and dorsiflexion ( Fig. 21-24) .

Fibularis (Peroneus) Longus, Fibularis (Peroneus) Brevis, and Fibularis (Peroneus) Tertius Muscles

The lateral compartment muscles and the fibularis (peroneus) tertius muscle produce the motion of eversion. The patient is positioned in supine, with the foot over the edge of the table and the ankle in the anatomic position. Resistance is applied to the lateral border of the forefoot ( Fig. 21-25).

Digits

Grades for the toes differ from the standard format because gravity is not considered a factor.

• 0: No contraction.
• Trace or 1: Muscle contraction is palpated, but no movement occurs.
• Poor or 2: Subject can partially complete the ROM.
• Fair or 3: Subject can complete the test range.
• Good or 4: Subject can complete the test range but is able to take less resistance on the test side than on the opposite side.
• N or 5: Subject can complete the test range and take maximal resistance on the test side as compared with the normal side.

Flexor Hallucis Brevis and Longus Muscles

The flexor hallucis brevis and FHL muscles produce MTP joint flexion and IP joint flexion. The foot is maintained in midposition. The first metatarsal is stabilized, and resistance is applied beneath the proximal and distal phalanx of the great toe into toe extension.

Flexor Digitorum Brevis and Longus Muscles

The flexor digitorum longus and brevis muscles produce IP joint flexion. The motion is tested with the foot in the anatomic position. If the gastrocnemius muscle is shortened, preventing the ankle from assuming the anatomic position, the knee is flexed. The toes may be tested simultaneously.

The foot is held in the midposition and the metatarsals are stabilized. Resistance is applied beneath the distal and proximal phalanges .

Extensor Hallucis Longus and Brevis Muscles

The extensor hallucis longus and the EHB muscles produce the motion of extension of the IP and MTP joints. The foot is maintained in midposition. Resistance is applied to the posterior aspect of both phalanges of the first digit into toe flexion.

Extensor Digitorum Longus and Brevis Muscles

The extensor digitorum longus and the EDB muscles produce the motion of extension at the MTP and IP joints of the lateral four digits from a flexed position . Resistance is applied to the posterior (dorsal) surface of the proximal and distal phalanges into toe flexion.

Intrinsic Muscles of the Foot

The intrinsic muscles of the foot are tested with the patient in either the supine or the sitting position. Most subjects are unable to voluntarily contract the intrinsic muscles of the foot individually.

Abductor Hallucis Muscle

The metatarsals are stabilized, and resistance is applied medially to the distal end of the first phalanx .

Adductor Hallucis Muscle

The metatarsals are stabilized, and resistance is applied to the lateral side of the proximal phalanx of the first digit .

Lumbrical Muscles

The lateral four metatarsals are stabilized, and resistance is applied to the middle and distal phalanges of the lateral four digits.

Plantar Interossei Muscles

The lateral three metatarsals are stabilized, and resistance is applied to the middle and distal phalanges.

Posterior (Dorsal) Interossei and Abductor Digiti Minimi Muscles

The metatarsals are stabilized and resistance is applied:

• Posterior (Dorsal) interossei.Applied to the middle and distal phalanges.
• Abductor digiti minimi.Applied to the lateral side of the proximal phalanx of the fifth digit.

Functional Tests

Subjective Tests

The Ankle Joint Functional Assessment Tool

The Ankle Joint Functional Assessment Tool (AJFAT) 155is composed of 12 questions rating the ankle's functional ability ( Table 21-9). The AJFAT questions are based on assessment tools previously used for evaluating the functional level of the knee. 156– 158

The Foot Function Index

The Foot Function Index (FFI) 159is a functional outcome measure that consists of three subsections: pain, disability ( Table 21-9), and activity. A study by Budiman-Mak et al. 159examined test–retest reliability (intraclass correlation coefficient, ICC = 0.87), internal consistency (0.96), and construct and criterion validity of the questionnaire.

Objective Tests

Weight-Bearing Tests

In weight-bearing, with the feet fixed, the patient should be asked to perform the following while the clinician notes any reproduction of pain or abnormal motion:

• Weight-bearing on the foot borders.The patient is asked to bear weight on the medial borders of the feet while keeping the knees extended. The patient is then asked to bear weight on the lateral borders of the feet while maintaining the knee extension.
• Heel raising.In addition to being a general screening test, heel raising also assesses the ability of the medial arch to increase and produce a supinated/inverted arch. Under normal conditions, the tibialis posterior tendon inverts the hind foot as the patient raises their heel. With poor or absent tibialis posterior function, the patient just rolls on the outside of the foot and demonstrates a decreased ability to unilaterally raise the heel.
• Twisting of the lower leg.Twisting tests the ability of the foot to supinate on the ipsilateral side, and its ability to pronate on the contralateral side.

The results of these tests may not be helpful in forming an actionable diagnosis, but they may be the only way to reproduce the patient's symptoms and will therefore be of use in the formation of a diagnosis.

Single-Leg Stance Test

Chronic ankle instability is a frequent consequence after lateral ankle sprain. The inability to maintain quiet stance during single standing has consistently been shown to be associated with ankle instability. 160

Star Excursion Balance Test

The star excursion balance test (SEBT) is a clinical test purported to detect functional performance deficits associated with lower extremity pathology in otherwise healthy individuals. 160The SEBT consists of a series of lower extremity reaching tasks in directions that challenge subjects' postural control, strength, ROM, and proprioceptive abilities. The farther a subject can reach with one leg while balancing on the opposite leg, the better the functional performance they are deemed to have. The subject stands barefoot at the center of the grid with eight lines extending in a star pattern at 45-degree increments from the center of the grid. 161Subjects are asked to maintain a single-leg stance while reaching with the contralateral leg to touch as far as possible along the chosen line, and then to return to a bilateral stance while maintaining their equilibrium. 161The test is then repeated using the other leg.

Functional Examination

See Table 21-8.

Passive Articular Mobility

Passive articular mobility tests assess the accessory motions available between the joint surfaces. These same techniques can be used to increase joint play using the varying grades of mobilization (see “Joint Mobilizations” in Techniques to Increase Joint Mobility). As with any other joint complex, the quality and quantity of joint motion must be assessed to determine the level of joint involvement. The joint play movement tests must be performed on both sides so that comparisons can be made. The patient is positioned in lying.

Distal Tibiofibular Joint

Although the glide at this joint would appear to be negligible, Mulligan has proposed that some ankle inversion injuries may be the result of a distal fibular positional fault. One study 162examined the distal tibiofibular posterior glide of the ankles of 25 subjects for joint excursion. Of the 50 ankles, six had been diagnosed with an acute ankle sprain. Two ankles exhibited an increase in excursion, both of which of had been sprained suggesting that in approximately one-third of diagnosed ankle sprains, the true cause might be an anterior positional fault of the distal fibular on the tibia.

To perform the mobility tests of this joint, the patient is placed in supine and the clinician grips the tibia and fibula using one hand for each ( Fig. 21-26). While one hand prevents downward motion of the medial malleolus, the other hand glides the fibula anteriorly and posteriorly in relation to the tibia. To assess the motion of the tibial component, one hand stabilizes the fibula and lateral malleolus, while the other hand glides the tibia anteriorly and posteriorly in relation to the fibula. Theoretically, a superior and inferior glide can be assessed at this joint, but it is unclear whether information provided by such testing would help the clinician in making a diagnosis or designing a plan of care.

Long-Axis Distraction of Ankle and Foot

The clinician stabilizes the proximal segment and applies traction to the distal segment. This test is performed at the talocrural joint ( Fig. 21-27), the subtalar joint ( Fig. 21-28), the MTP joints ( Fig 21-29), and the IP joints ( Fig 21-30).

Anterior–Posterior Glide

To test the anterior glide of the talocrural joint, the clinician stabilizes the tibia and fibula and draws the talus and foot forward together ( Fig. 21-31). Pushing the talus and foot together in a posterior direction on the tibia and fibula ( Fig. 21-32) tests the posterior movement. The anterior glide of the talus assesses the joint's ability to move into plantar flexion, whereas the posterior glide of the talus assesses the joint's ability to move into dorsiflexion.

The anterior–posterior glides can also be applied to the midtarsal ( Fig. 21-33), intertarsal ( Figs. 21-34and 21-35), MTP ( Fig. 21-36), and IP ( Fig. 21-37) joints.

Calcaneal Inversion–Eversion (Subtalar)

Subtalar joint motion is extremely important to normal foot function. A loss of eversion causes weight-bearing to occur along the lateral side of the ankle joint. The patient lies in the prone position with the knee slightly flexed and supported by a pillow, while the clinician stands at the foot of the table, facing the patient. The clinician grasps the calcaneus in one hand, while the other hand locks the talus. The calcaneus is passively inverted (varus) and everted (valgus) on the talus ( Fig. 21-38). The amount and quality of the motions as compared with the other foot are noted. Although some differences exist, generally calcaneal eversion will measure 5–10 degrees, while calcaneal inversion will measure approximately 20–30 degrees. 20, 94, 141A similar technique can be used to assess medial and lateral gapping at this joint. Medial gapping is associated with subtalar joint eversion, whereas lateral gapping is associated with subtalar joint inversion.

Midtarsal Joint Motion

The rotational movements of the midtarsal joint, which allow the forefoot to twist on the rearfoot, can be observed in the non–weight-bearing position. The clinician stabilizes the calcaneus with one hand, while inverting and everting the foot at the midtarsal joint with the other hand ( Fig. 21-39). 85

First MTP Joint (First Ray) Motion

The patient lies in supine position, with the clinician at the foot of the table facing away from the patient. The clinician grasps and locks the first MTP joint, before grasping the great toe and moving it into extension and flexion (posteriorly (dorsally) and anteriorly (ventrally), respectively) ( Fig. 21-40). Long-axis distraction and compression can also be applied ( Fig. 21-41) to assess capsular and articular integrity, respectively.

Limited range may result from a combination of biomechanical factors such as excessive pronation or joint glide restriction. 163To examine the conjunct rotation of the metatarsals, the clinician locks the second metatarsal to evaluate the first and locks the third to evaluate the second. The quantity and quality of motion is noted and compared with the other side.

Special Tests

Special tests are merely confirmatory tests and should not be used alone to form a diagnosis. Selection for their use is at the discretion of the clinician and is based on a complete patient history. The results from these tests are used in conjunction with the other clinical findings. To assure accuracy with these tests, both sides should be tested for comparison.

Assessing Ankle Girth

Physical therapists need a reliable method by which to measure ankle girth following injury so that there can be clinical quantification of the volume of edema. Two methods are described:

• Figure-of-eight tape method.The patient lies in the supine position or seated. The clinician places a tape measure midway between the tibialis anterior tendon and lateral malleolus. The tape is then drawn medially and is placed just distal to the navicular tuberosity. The tape is then pulled across the arch and just proximal to the fifth metatarsal. The tape is then pulled across the tibialis anterior tendon and around the ankle to a point just distal to the medial malleolus, before being finally pulled across the Achilles tendon and placed just distal to the lateral malleolus and across the start of the tape. Tatro-Adams et al. 164reported the ankle figure-of-eight method to be a reliable tool for measuring ankle girth. ( Fig. 21-42)
• Volumetry method.A volumeter is filled with water, and the patient's foot is placed into the volumeter with toe tips touching the front wall. The amount of water displaced is measured.

Petersen et al. performed a study to determine the interrater and intrarater reliability of water volumetry and the figure-of-eight method on subjects with ankle joint swelling and found high interrater reliability for both the water volumetry (ICC = 0.99) and the figure-of-eight methods (ICC = 0.98). In addition, intrarater reliability was high for both (ICCs = 0.98–0.99). The authors concluded that both methods are reliable measures of ankle swelling, although they recommended the figure-of-eight method because of its ease of use, time efficiency, and cost effectiveness. However, water volumetry may be more appropriate when measuring diffuse lower extremity swelling.

Ligamentous Stress Tests

The examination of the ligamentous structures in the ankle and foot is essential, not only because of their vast array but also because of the amount of stability that they provide. Positive results for the ligamentous stability tests include excessive movement, as compared with the same test on the uninvolved extremity, pain (depending on the severity), or apprehension.

Mortise/Syndesmosis

Cotton (Clunk) Test

The patient lies in supine position with their foot over the end of the bed. One hand is used to stabilize the distal leg on the bed, while the clinician uses the other hand to grasp the heel and move the calcaneus laterally (see Fig. 21-43). 165A clunk can be felt as the talus hits the tibia and fibula, if there has been significant mortise widening. 129Beumer et al. 166found this test to have a sensitivity of 46%.

Kleiger (External Rotation) Test

The Kleiger (external rotation) test 17, 137, 167is a general test to implicate the syndesmosis if pain is produced over the anterior or posterior tibiofibular ligaments and the interosseous membrane, but can also be used to assess the integrity of the medial (deltoid) ligament of the ankle complex. 168, 169If this test is positive, further testing is necessary to determine the source of the symptoms.

The patient sits with their legs dangling over the end of the bed, the knee flexed to approximately 90 degrees, and the foot relaxed. The clinician stabilizes the lower leg with one hand and, using the other hand, grasps the foot and externally rotates it ( Fig. 21-44). Pain experienced at the anterolateral aspect of the distal tibiofibular syndesmosis is a positive sign for syndesmosis injury, 170whereas pain on the medial aspect of the ankle and/or displacement of the talus from the medial malleolus (depending on severity) with the ankle positioned in plantar flexion may indicate a tear of the medial (deltoid) ligament of the ankle. Alonso et al. 170reported data that indicate that the external rotation stress test is more reliable than the squeeze test and the dorsiflexion–compression test for diagnosing syndesmosis injuries.

The Point Test 170, 171

The point test, also referred to as the palpation test, is used to impose pressure on the anterior distal tibiofibular syndesmosis. The patient can be positioned in supine or sitting. The clinician applies pressure directly over the anterior aspect of the distal tibiofibular syndesmosis ( Fig. 21-45). Pressure is applied gradually, and a positive test involves a report of pain by the patient.

The Dorsiflexion Maneuver 171, 172

The dorsiflexion maneuver is performed to force the wider anterior portion of the talar dome into the ankle mortise, thereby inducing separation of the distal fibula and tibia. The patient sits at the edge of the examination table, and the clinician stabilizes the patient's leg with one hand, while the clinician's other hand passively moves the foot into dorsiflexion ( Fig. 21-46). Pain experienced at the distal tibiofibular syndesmosis is a positive test result. A variation of the dorsiflexion maneuver exists, known as the dorsiflexion compression test, 170which involves patients moving their ankle joints into extreme dorsiflexion in bilateral weight-bearing. Patients are asked to note the pain they experience in this position and the position of the tibia is noted with an inclinometer. The patient then assumes an upright position, and the clinician applies medial–lateral compression with two hands on the malleoli of the injured leg. The clinician maintains the medial–lateral compression, as the patient is asked to move the ankles into dorsiflexion again and to report if the end-range pain has changed compared with the previous movement. A positive test result is either a reported reduction in the end-range pain or an increase in dorsiflexion ROM.

Fibula Translation Test

The patient is placed in the side-lying position with the tested leg uppermost. The clinician applies an anterior and posterior force on the fibula at the level of the syndesmosis ( Fig. 21-47). A positive test is pain during translation and more displacement of the fibula than the compared side. Although a cadaver study by Beumer et al. 166found this test to have a sensitivity of 82% and specificity of 88% (LR+ 6.8; LR− 0.2), the study only found increased translation when all ligaments were removed in the cadavers.

The One-Legged Hop Test 171, 173

The one-legged hop test is performed by having the patient stand on the injured leg and hop continuously. Nussbaum et al. 173reported that patients with syndesmosis injuries could not complete 10 repetitions of unilateral hopping without significant pain. However, the one-legged hop test should be used with caution, and perhaps only if the other special tests are negative, because performing this test may impose further separation of the distal tibiofibular syndesmosis. 171

The Crossed-Leg Test 171, 174

The crossed-leg test mimics the squeeze test (see later) and attempts to induce separation of the distal syndesmosis. The patient sits in a chair, with the injured leg resting across the knee of the uninjured leg. The resting point should be at approximately mid-calf. The clinician then applies a gentle force on the medial aspect of the knee of the test leg ( Fig. 21-48). Pain experienced in the area of the distal syndesmosis suggests the presence of injury. This test may not be useful for patients with knee or hip pathology because it may be difficult for them to assume the test position. Reliability and validity data for this test are not yet available.

The Heel-Thump Test 171, 175

The heel-thump test is performed to force the talus into the mortise, in an attempt to impose separation of the distal syndesmosis. The patient lies at the edge of the examination table, with the ankle resting in plantar flexion. The clinician holds the patient's leg with one hand and with the other hand applies a gentle but firm thump on the heel with their fist ( Fig. 21-49). This force is applied at the center of the heel and in line with the long axis of the tibia. Pain experienced at the distal tibiofibular syndesmosis suggests the presence of injury. Although the heel thump test has been recommended to help differentiate between a syndesmotic sprain and a lateral ankle sprain, this test may not be specific for a syndesmotic sprain as the test has also been recommended to assess the possible presence of tibial stress fractures. 176Reliability and validity data for this test are not yet available.

Posterior Drawer Test

The posterior drawer test can also be used to test for the presence of instability at the distal tibiofibular joint. The patient is supine. The hip and knee are flexed to provide as much dorsiflexion of the ankle as possible. This drives the wide anterior part of the talus back into the mortise. An anterior stabilizing force is then applied to the cruris, and the foot and talus are translated posteriorly ( Fig. 21-50). If the distal tibiofibular joint is stable, there will be no drawer available, but if there is instability, there will be a drawer.

Squeeze (Distal Tibiofibular Compression) Test

In the squeeze test, the patient lies in supine or side-lying position and the clinician squeezes the upper to middle third of the leg at a point approximately 6–8 inches below the knee ( Fig. 21-51). 137Pain felt in the distal third of the leg may indicate a compromised syndesmosis, if the presence of a tibia and/or fibula fracture, calf contusion, or compartment syndrome has been ruled out. 126, 168

Lateral Collaterals

The lateral collateral ligaments of the ankle resist inversion. An additional function is to prevent excessive varus movement, especially during plantar flexion. In extreme plantar flexion, the mortise no longer stabilizes the broader anterior part of the talus, and varus movement of the ankle is then possible.

Calcaneus Tilt

The patient lies in the supine position. The lower leg is stabilized using a lumbrical grip, while the other hand grasps the foot and calcaneus. The clinician applies a medially directed force in an attempt to adduct the calcaneus, thereby gapping the lateral side of the ankle ( Fig. 21-52). Pain on the lateral aspect of the ankle with this test, and/or displacement (depending on severity), may indicate a sprain of the ligament. Hertel et al. 177found this test to have a sensitivity of 78% and a specificity of 75% (LR+ 3.1; LR− 0.29).

Talar Tilt

This test is used to determine whether the CFL is torn. The patient lies in a supine or side-lying position with the foot relaxed and the knee flexed. The clinician places the foot in the anatomical (90 degrees) position to bring the CFL perpendicular to the long axis of the talar. The talus is then tilted from side to side into adduction and abduction ( Fig. 21-53). Adduction tests the CFL and, to some degree, the ATFL, whereas abduction stresses the deltoid ligament. No diagnostic accuracy studies have been performed to determine the sensitivity and specificity of this test.