The talus has no muscular insertions. Any movement of the talus in relation to the tibia is realized by passive transmission of motion by means of the ligamentous guiding system (Van Dijk 1994). Active motion is realized by the long foot muscles, which insert onto the midtarsal and metatarsal bones. The posterior joint capsule envelops the posterior joint space. It is attached to the posterior surface of the tibia and to the talus at the border between bone and cartilage. The outer fibrous layer of the capsule is continuous with the fibrous layer of the periosteum. The posterior capsule is lax in plantar flexion and tight in dorsiflexion (Van den Bekerom et al. 2008). The posterior talofibular ligament (PTFL) passes almost horizontal from a groove at the inside of the posterior margin of the lateral malleolus to the posterior prominence of the talus. Frequently, a separate bundle of fibers originates from the same groove on the inside of the posterior part of the lateral malleolus and runs below the posterior tibiofibular ligament to the posterior surface of the tibia (Ludolph and Hierholzer 1986). Both structures are incorporated in the joint capsule (De Leeuw et al. 2010). In plantar flexion and neutral position, the ligament is relaxed, while in dorsiflexion the ligament is tensed. The posterior tibiofibular ligament is a flat fibrous band, with the distal fibers being the longest. The fibers originate from the posterior tubercle of the tibia and run at an approximate angle of 45° distally and laterally, where they attach to the posterior aspect of the fibula. Sometimes the ligament consists of a double structure. The proximal part crosses directly from the tibia to the posterior part of the fibula, whereas the distal section is part of the joint capsule and runs to a groove on the inner side of the posterior margin of the lateral malleolus. It can be recognized as a ligament structure when observing the posterior joint capsule from the inside of the joint as is done in arthroscopy (Van Dijk 1990).

The most prominent posterior part of the talus is located posterolateral. Apart from the posterior joint capsule, the posterior talofibular ligament attaches to this posterior talar process. Medial from this prominent bony process is the flexor hallucis longus. The flexor hallucis longus tendon thus separates the posterior talar process from the medial talar tubercle. The posterior talar process forms the roof of the posterior facet of the subtalar joint. Embryological, the body of the talus and posterior talar process are separate ossification centers. The posterior talar process appears as a separate ossicle, which is called “os trigonum,” between the 8th and 10th years of life. The body of the talus is usually visible on radiographs around 7 months. The os trigonum may be considered as a secondary ossification center, similar to the calcaneal apophysis. The os trigonum usually fuses with the talus within a year of its appearance. In about 7 % of the normal adult population, however, it is still present as an accessory bone (Salyers and Fu 1989). It can be present bilaterally or unilaterally.

Posterior ankle impingement can be caused by overuse or trauma. It is important to distinguish between these two, because posterior impingement resulting from overuse has a better prognosis (Stibbe et al. 1994).

A diagnosis or differential diagnosis can be made on the basis of the patient’s history, physical examination, and radiographs.

In the differential diagnosis, the following diagnoses are considered:

Conditions such as posterior tibial tendinitis, chronic synovitis of the ankle joint, posterior osteochondral defect, or osteoid osteoma usually have a different clinical presentation (Van Dijk 1990; Van Dijk and Scholte 1997). A loose body in the posterior ankle joint can clinically present as posterior ankle impingement. Flexor hallucis longus tendinitis in ballet dancers is most important in the differential diagnosis. The pain is located posteromedial. It is present in “plié” and especially in “grand plié.” The flexor hallucis longus tendon can be palpated behind the medial malleolus. By asking the patient to repetitively flex the toes with the ankle in 10°–20° of plantar flexion, the flexor hallucis longus tendon can be palpated in its gliding channel behind the medial malleolus. The tendon glides up and down under the palpating finger of the examiner. In case of stenosing tendinitis or chronic inflammation, we feel for crepitus and pain, while sometimes a nodule in the tendon can be felt to move up and down under the palpating finger. Subtalar pathology of the posteromedial compartment is called “dancers’ heel” (Van Dijk et al. 2001). The movement in the subtalar joint is a “gliding” and rotating movement. Even though there is little movement of the subtalar joint surfaces in relation to each other, a statistically significant increase in degenerative subtalar joint disease in retired professional female ballet dancers compared with a matched-paired control group was found (Van Dijk et al. 1995). The “dancers’ heel” can be subdivided into three stages.

Because of the close relationship between the structures located in the tarsal tunnel and the posteromedial aspect of the subtalar joint, the dancers’ heel can give rise to secondary tendon pathology.

Nonoperative treatment involves modification of activities, physical therapy (massage, stretching, and muscle strengthening), icing, use of nonsteroidal anti-inflammatory medication, and injection of steroids. The steroids are injected posterolateral into the posterior joint capsule between the prominent posterior tibial talar process and the posterior tibial edge. Physicians who are not familiar with the local anatomy are advised to perform the infiltration under fluoroscopic control. Analysis and correction of the patient’s dance technique involves correction of sickling. Sickling in valgus is the result of hypertonic peroneal muscles and relative weakness of the posterior tibial tendon. Sickling in varus can be the result of a weakness of the peroneal muscles. Operative treatment involves the removal of a hypertrophic posterior joint capsule, an os trigonum, a hypertrophic posterior talar process, a pseudarthrotic fragment, calcifications, osteophytes, or loose bodies (Fig. 13.10).