The ankle is a hinge-type articulation between the distal tibia, the two malleoli, and the talus (Fig. 6.1). The articular surface is covered with hyaline cartilage, which is susceptible to arthritis. The joint is surrounded by a dense capsule that helps strengthen the ankle. The joint capsule is lined with a synovial membrane that attaches to the articular cartilage. The ankle joint is innervated by the deep peroneal and tibial nerves.

The major ligaments of the ankle joint include the talofibular, anterior talofibular, calcaneofibular, and posterior talofibular ligaments, which provide the majority of strength to the ankle joint (Fig. 6.2). The calcaneofibular ligament is not as strong as the deltoid ligament and is susceptible to strain. The calcaneofibular ligament runs from the anterior border of the lateral malleolus to the lateral surface of the calcaneus (Figs. 6.3 and 6.4).

The calcaneofibular ligament runs from the anterior border of the lateral malleolus to the lateral surface of the calcaneus (Fig. 6.3). Also known as the fibulocalcaneal ligament, the calcaneofibular ligament is susceptible to strain at the joint line or avulsion at its origin or insertion. The calcaneofibular ligament is frequently injured from inversion injuries to the ankle that occur when tripping when wearing high heels, stepping off a high curb, landing hard or running on hard uneven surfaces, and during dancing, soccer, and basketball. The pain of calcaneofibular ligament damage is localized anterior and inferior to the lateral malleolus and is made worse with inversion of the ankle joint. Point tenderness just below and behind the lateral malleolus is often present on physical examination. Significant swelling and ecchymosis are often evident after acute injury. Activity, especially involving weight bearing, plantar flexion,
and inversion of the ankle will exacerbate the pain. Local heat and decreased activity as well as elevation of the affected ankle may provide a modicum of relief. Sleep disturbance is common in patients suffering from trauma to the calcaneofibular ligament of the ankle. Coexistent fracture, bursitis, tendinitis, arthritis, or internal derangement of the ankle may confuse the clinical picture after trauma to the knee joint making clinical diagnosis difficult.

Plain radiographs and/or arthrography are indicated in all patients who present with calcaneofibular ligament pain, especially after ankle trauma (Figs. 6.5 and 6.6). Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging, arthrography, and/or ultrasound imaging of the ankle are indicated if internal derangement or occult mass or tumor is suspected as well as to confirm the diagnosis of suspected calcaneofibular ligament injury (Fig. 6.7). Bone scan may be useful to identify occult stress fractures involving the calcaneus, especially if trauma has occurred (Fig. 6.8).