One of the four major ligaments of the ankle joint, the deltoid ligament, is a strong, triangular-shaped, bilaminar ligament that runs from the medial malleolus, with the deep layer of the ligament attaching below to the medial body of the talus and the superficial layer of the ligament attaching to the medial talus, the sustentaculum tali of the calcaneus, and the navicular tuberosity (Figs. 162.1 and 162.2). Also known as the medial ligament of talocrural joint, the deltoid ligament is susceptible to strain at the joint line or avulsion at its origin or insertion. The deltoid ligament is frequently injured from eversion injuries to the ankle that occur when tripping when high heels, landing hard on uneven surfaces, and during dancing, soccer, and American football (Fig. 162.3). The pain of deltoid ligament damage is localized to the medial ankle and is made worse with plantar flexion and eversion of the ankle joint. Significant swelling and ecchymosis are often evident after acute injury (Fig. 162.4). Activity, especially involving weight bearing, plantar flexion, and eversion 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 deltoid ligament of the ankle. Coexistent fracture, bursitis, tendonitis, arthritis, or internal derangement of the ankle may confuse the clinical picture after trauma to the knee joint making clinical diagnosis difficult.

Plain radiographs are indicated in all patients who present with deltoid ligament pain, especially after ankle trauma (Fig. 162.5). 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 and/or ultrasound imaging of the ankle is indicated if internal derangement or occult mass or tumor is suspected as well as to confirm the diagnosis of suspected deltoid ligament injury (Fig. 162.6). Bone scan may be useful to identify occult stress fractures involving the joint, especially if trauma has occurred.

The ankle is a hinge-type articulation between the distal tibia, the two malleoli, and the talus. 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 deltoid, anterior talofibular, calcaneofibular, and posterior talofibular ligaments, which provide the majority of strength to the ankle joint (see Fig. 162.1). The deltoid ligament is exceptionally strong and is not as subject to strain as the anterior talofibular ligament. The triangular-shaped deltoid ligament is made up of a number of smaller separate ligaments including the anterior tibiotalar ligament, tibiocalcaneal ligament, posterior tibiotalar ligament, and tibionavicular ligament. These ligaments are arranged in two layers. Both layers attach above to the medial malleolus. A deep layer attaches below to the medial body of the talus, with the superficial fibers attaching to the medial talus, the sustentaculum tali of the calcaneus, and the navicular tuberosity.