Lateral ankle ligament complex injuries are a common sport-associated injury. The most common mechanism of injury is inversion and internal rotation of the foot. Nonoperative management, including functional rehabilitation, is the mainstay of treatment for acute injuries. Up to 20% of acute injuries may not respond to conservative management and progress to chronic lateral ankle pain and instability.

The lateral ankle is supported by both static and dynamic restraints. Static structures include the bony congruity of the tibiotalar joint and the lateral ankle ligaments: the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL). The ATFL is the most commonly injured, and may be the first or only ligament injured with ankle inversion injuries. It acts to limit anterior displacement of the talus when the ankle is in neutral. The ATFL is most commonly composed of two bands (varies from one to three bands) separated by perforating arterial branches. The inferior band is taut in ankle dorsiflexion while the superior band is taut in ankle plantarflexion. The ATFL originates at the anterior edge of the lateral malleolus and runs anteromedially to insert on the lateral talar neck. The ligament is near horizontal with the ankle in neutral position.

The CFL originates from the distal tip of the lateral malleolus just inferior to the ATFL and runs posterior, inferior, and medial to insert on the posterolateral calcaneus. It lies just deep to the peroneal tendons. Laxity in the CFL leads to increased talar tilt when the ankle is stressed to inversion at 90° of neutral position.

The PTFL is the strongest of the three lateral ankle ligaments, and is rarely injured. It originates from the medial surface of the lateral malleolus, deep to the peroneal tendons, and inserts on the lateral tubercle of the talus, just lateral to the flexor hallucis longus. In plantarflexion and neutral, the PTFL is relaxed; in dorsiflexion, the ligament is taut.

The lateral ankle is further supported by the peroneus brevis and peroneus longus tendons, which serve as dynamic stabilizers of the lateral ankle. The tendons run posterior to the fibula in the peroneal groove, held in place by the superior peroneal retinaculum. The tendons then course superficial to the PTFL and CFL to run along the lateral calcaneus under the inferior peroneal retinaculum.

Conservative management is the primary treatment choice for the majority of acute lateral ankle ligament complex injuries, and consists of a short period of immobilization in a walking boot (less then 3 weeks), activity modification, and functional rehabilitation. Physical therapy should emphasize peroneal tendon strengthening, decreasing edema, stretching, gait training, and proprioception. Surgery is reserved for high-level athletes and patients with continued ankle instability despite a course of supervised aggressive physical therapy.

Chronic lateral ankle instability may be defined as mechanical instability of the lateral ankle with or without persistent pain after 3 to 6 months of conservative management. Surgery is contraindicated in patients with lateral ankle pain in the absence of lateral ankle instability. Relative contraindications include connective tissue disorders (e.g., Ehlers-Danlos syndrome), peripheral vascular disease, and patients that cannot follow postoperative protocols. An MRI without contrast is obtained preoperatively to evaluate the ankle for other pathologies, including concomitant osteochondral lesions, peroneal tendon pathology, bone bruising, or impingement. An MRI can also show lax or wavy ligaments or nonvisualization of the lateral ankle ligaments. Another important preoperative consideration is the presence of hindfoot deformity. A varus hindfoot increases the risk of lateral ankle ligament complex injuries, and increases stress on the lateral ligament complex repair. All pathologies that are associated with chronic ankle stability should be addressed at the time of surgery. The presence of these concomitant findings may alter final rehabilitation protocol based on severity of pathology and clinician preference.