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ABSTRACT: The Evans operation for lateral instability of the ankle is a simple procedure technically. The peroneus brevis tendon is passed through a drill hole in the distal fibula and fastened under tension, producing a strong autogenous lateral ligament of the ankle. In a series of five patients followed an average of 21A years postoperatively, the Evans operation has resulted in a stable ankle in each instance, with the patients able to carry out athletic activities as desired. A loss of inversion of the ankle ranging from 10° to 30° was noted in each patient.
Discussion
Recurrent disability of the ankle due to lateral ligament rupture is frequently undiagnosed and fails to receive appropriate treatment.
The lateral ligaments of the ankle joint consist of the anterior and posterior talofibular ligaments, the lateral talocalcaneal ligament, and the calcaneofibular ligament (Fig. 1). Cadaver studies by Leonard,1 Brostrom,2 and Chrisman Snook3 showed that the anterior talofibular ligament was the most frequently ruptured and the most important component of the lateral ligaments of the ankle. Minor varus tilting of the talus occurred after section of either the anterior talofibular of calcaneofibular ligament, but gross talar tilting occurred only after both ligaments were sectioned.3
Subtalar joint instability occurred only when the calcaneofibular and lateral talocalcaneal ligaments were divided.
Differences of opinion exist as to what degree of lateral tilting of the talus on forced inversion constitutes clinical lateral instability of the ankle.2-5 Rubin and Witten6 demonstrated taltar tilting in "normal" asymptomatic males ranging up to 23°; however, the great majority ranged from 0-5°. Peroneal spasm may restrict talar tilt testing unless local or general anesthesia is employed. The consensus is that a talar tilt of 5° or more is significant, providing that the opposite ankle (examined routinely) does not show a similar angular tilt.
The inversion stress test by radiography is a valuable adjunct in diagnosing lateral instability of the ankle. Of greater importance is the history of repeated giving way of the ankle with minimal or no trauma; and physical examination characteristically shows a sulcus in the lateral aspect of the ankle anterior to the lateral malleolus on forced inversion. Frequently a clunking sensation is felt when the ankle is inverted strongly and then swung into neutral...