Pure ankle dislocation: management with early weight bearing and mobilization

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Ankle dislocation without malleolar fracture is very rare with few reports in the literature.1 The infrequent occurrence of pure ankle dislocation is attributed to the strength of the ligamentous structures exceeding that local bone, making dislocations with fracture common.5 Non‐operative cast immobilization and repair of ligamentous structures have been described;1 here we describe that pure tibiotalar ankle dislocation that is stable after reduction can be successfully treated with controlled ankle motion (CAM) orthosis.
A 17‐year‐old woman presented to our centre with an isolated right ankle dislocation sustained during an amateur netball game. She described an inversion, internal rotation injury after falling awkwardly on another player's foot. She had no previous ankle injuries and an unremarkable past medical history. Examination revealed a closed, deformed right ankle that was well perfused with intact distal neurovascular function. X‐ray revealed a pure posteromedial dislocation of her right tibiotalar joint with no malleolar fractures or syndesmotic diastasis (Figs 1).
Reduction was performed in the emergency department with sedation using gentle traction (Fig. 3). Examination after reduction revealed stable ankle joint. Eversion and inversion talar tests were positive; however, no sulcus sign could be produced with anterior draw. A below knee backslab was applied and the patient was admitted for elevation and further imaging.
Magnetic resonance imaging demonstrated a complete rupture of the anterior talofibular ligament, partial tear of the deltoid ligament and no fractures. Given the patients stability on examination, a decision was made to change her from a backslab to a CAM orthosis and allow her to weight bear as tolerated with crutches.
Upon review at 2 weeks, she was found to have a stable ankle joint, minimal swelling and minimal discomfort. By 6 weeks, she had recovered a full range of motion and almost normal function; she was full weight bearing without a gait aid. At this time, she was weaned to an ankle brace and returned to competitive sport at 6 months.
It was originally thought that ankle dislocation could not occur without fracture.6 Only a small number of pure ankle dislocations have been reported in the literature. Wilson described a total of 16 cases in a series collected between 1913 and 1939.1 He concluded that most patients would have a good long‐term recovery if an adequate reduction was achieved and the patient was instructed not to weight bear during their recovery.
Axial loading when applied to a maximally plantar flexed foot in inversion or eversion causes a posteromedial or posterolateral dislocation, respectively. Fernandes confirmed this mechanism in cadaveric specimens in 1976.7 Rasmussen confirmed the ankle mortise to be less stable in maximal plantar flexion.8 In this position, the anterior talofibular ligament, calcaneofibular ligament and anterolateral aspect of the joint capsule are most vulnerable to disruption. Despite this, repair of the medial and lateral ligament complexes do not appear to have any effect on long‐term outcome.3
Although there is no formal guideline as to how ankle dislocation without fracture should be managed, the majority of reports in the literature suggest prompt reduction, cast immobilization and a 4–6 week period of non‐weight bearing.9 Open ankle dislocations occur less frequently and it is recommended that they be washed out and debrided before being immobilized.10
The use of a removable CAM orthosis in the management of pure ankle dislocation has not been previously reported in the literature. This case demonstrates that the use of a removable orthosis, after careful evaluation of ankle stability, allows our patient to bear weight, engage in a physiotherapy programme and undertake activities of daily living.
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