Pure dislocation of the ankle is an extremely rare injury accounting for only 0.065% of all ankle injuries and 0.46% of all ankle dislocations. The mechanism of the injury generally consists of high-energy trauma which is associated with a combination of plantar flexion and inversion or eversion of the foot. We present a case of a 22-year-old male patient who sustained a closed pure ankle dislocation after a fall from a small height. He was treated conservatively with closed reduction and circumferential cast immobilization for six weeks, followed by a functional rehabilitation program. The patient presented to the emergency department with an acutely painful and deformed right ankle after falling from a height of 1 m (stairs). Radiographs showed a posteromedial ankle dislocation without fracture. Urgent closed reduction of the dislocation was performed and a posterior below-knee back slab was applied to immobilize the ankle. Dorsalis pedis and posterior tibial arteries were intact. Check X-rays confirmed proper reduction of the ankle joint. Post reduction computed tomography (CT) scan did not show any associated fractures. Magnetic resonance imaging (MRI) revealed a multiligamentous ankle injury and a small osteochondral lesion of the anteromedial talar dome. The back slab was changed to a below-knee circular cast two weeks later, as soon as the soft tissue swelling subsided. The cast was removed at the six-week follow-up and physiotherapy was initiated in order to gain functional rehabilitation and improve the range of motion. At the final follow-up (12 months), the ankle range of motion (ROM) was the same as the pre-injury status and the patient was able to return to his work. Pure ankle dislocation is a rare injury. A satisfactory outcome can be expected, provided that the appropriate conservative treatment followed by a strict rehabilitation protocol is applied.
Keywords: anterior talo-fibular ligament; calcaneofibular ligament; deltoid ligament; posteromedial ankle dislocation; pure ankle dislocation; tibiotalar dislocation.
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