Long-term functional outcome after surgery of chronic ankle instability. A 5-year follow-up study of the modified Evans procedure.

Chronic ankle instability is a rather common consequence of poorly healed rupture of the lateral ligaments of the ankle. In some rare cases, instability symptoms can be caused by general laxity of the joints, but since these cases are normally bilateral, they can easily be distinguished from posttraumatic instability. This report presents the long-term (average follow-up 4.6 years) functional outcome after a modified Evans tenodesis of 48 patients. The follow-up examination consisted of a questionnaire evaluating the subjective assessment of the ankle, and clinical examination measuring ankle stability, range of motion and swelling, and atrophy of the calf muscles. Additionally, the functional recovery of the ankle was assessed by a standardized performance test protocol. According to the subjective assessment, 25 subjects (52%) considered the ankle fully recovered, or at least much better than before surgery. In the performance test, however, only 17 subjects (35%) achieved an excellent or good score. In the performance test protocol, two functional tests, walking down a staircase and balancing on a square beam, best demonstrated the impaired function of the injured ankle. The modified Evans procedure could restore the stability of the ankle to the preinjury level, although the ankle range of motion was significantly impaired, and swelling of the ankle and atrophy of the calf muscles were frequent findings at the follow-up. In conclusion, surgical treatment of chronic ankle instability by the Evans procedure restores the mechanical stability of the joint, but too frequently the function of the ankle does not return to the pre-injury level.