The deltoid ligament is a multibanded complex with superficial and deep components.

It may be wise to differentiate the superficial and deep portions of the deltoid complex with respect to the joints they are spanning. The superficial ligaments cross two joints (the ankle and the subtalar joints) and the deep ligaments cross one joint (only the ankle joint), although differentiation is not always absolutely clear.¹⁰

The three superficial and more anterior bands are the tibionavicular, tibiospring, and tibiocalcaneal ligaments; the three deep bands are the anterior, intermediate, and posterior tibiotalar ligaments (FIG 1).¹

As the tibioligamentous portion of the superficial deltoid has a broad insertion on the “spring ligament,” this ligament complex may interplay with the deltoid ligament in the stabilization of the medial ankle joint and thus is not functionally separated from it (see FIG 1).³

Acute injuries to the medial ankle ligaments can occur during running downstairs, landing on an uneven surface, and dancing while the body is simultaneously rotated in the opposite direction. A key feature is whether the patient has sustained a pronation (eversion) trauma—for instance, an outward rotation of the foot during simultaneous inward rotation of the tibia.

Complete deltoid ligament ruptures are sometimes seen in association with lateral malleolar fractures or in specific bimalleolar fractures.

Chronic deltoid ligament insufficiency can be seen in a number of conditions, including posterior tibial tendon disorder, traumatic and sports-related deltoid disruptions, as well as valgus talar tilting in patients with previous triple arthrodesis or total ankle arthroplasty.

There is evidence that the medial ankle ligaments are more often injured than generally believed.⁴,⁵,⁶,⁸

Several structures contribute to the stabilization of the medial ankle, and in the case of injury, they are not involved in a uniform way. Medial ankle instability is thus not a single entity, and this has important consequences on the treatment strategy.

The findings of an exploratory, prospective study on 51 patients (53 ankles) has supported our belief that medial ankle instability without posterior tibial tendon dysfunction does exist as an entity.⁸ It is, however, not clear yet whether or to what extent such a medial ankle instability may cause a secondary posterior tibial dysfunction over time, as the tendon may become elongated, ruptured, or both.

What is clear from the literature is that a coexisting pronation deformity of the foot will lead to further deterioration over time, as the medial ankle ligaments are chronically overstretched.

The diagnosis of medial ankle instability is made on the basis of the patient’s history and the results of physical examination, including special maneuvers, and plain radiographs.

As mentioned earlier, medial instability is suspected if the patient complains of giving way, especially medially, when walking on even ground, downhill, or downstairs. Further signs can be pain at the anteromedial aspect of the ankle and sometimes pain on the lateral ankle, especially during dorsiflexion of the foot.

A history of chronic instability, manifested by recurrent injuries with pain, tenderness, and sometimes bruising over the medial and lateral ligaments, is considered to indicate combined medial and lateral instability that is thought to result in rotational instability of the talus in the ankle mortise.

Acute injuries may present with tenderness and hematoma at the medial side of the ankle.

Physical examination methods for chronic medial ankle instability should include the following:

A complete examination of the hindfoot should also include evaluating associated injuries and ruling out other possible causes. These include, among others:

Acute injury: Plain radiographs, including anteroposterior (AP) and lateral views, should be obtained to rule out bony avulsion fractures or associated injuries.

Chronic injury: Plain weight-bearing radiographs, including AP views of the foot and ankle (FIG 2), a lateral view of the foot, and a hindfoot alignment view,¹³ should be obtained to rule out old bony avulsion fractures, secondary deformities of the foot (eg, valgus malalignment of the heel, dislocation at the talonavicular joint), and tibiotalar alignment (eg, medial gapping of the joint due to incompetence of the deltoid ligament).

Stress radiographs may be helpful to identify incompetence of the deltoid ligament in the treatment of acute ankle fractures,¹⁴ but they are not helpful in chronic conditions.¹⁰

A computed tomography (CT) scan may be obtained to detect a talocalcaneal coalition or bony fragmentation that involves the articular surfaces. A weight-bearing CT may be beneficial to recognize the specific position of talus within the ankle mortise and a potential incongruency in the subtalar joint, as given by an accompanying peritalar instability (FIG 3).

Magnetic resonance (MR) imaging may show an injury to the deltoid ligament (FIG 4), particularly in acute conditions, and it may also reveal pathologic conditions of the posterior tibial tendon.

Bony avulsion fracture of the medial malleolus (with or without fracture of the fibula or syndesmotic disruption)

Fixed flatfoot deformity (eg, acquired flatfoot deformity in adults after posterior tibial dysfunction)

Osteochondral injury

Talocalcaneal coalition

Although nonoperative management is controversial, patients with less instability, particularly those who have less of a giving way feeling and those who are less involved with high-level pronation sports activities, may be treated nonoperatively.

Nonoperative treatment consists of three components: