Disruption of the ankle syndesmosis: biomechanical study of the ligamentous restraints.

We investigated the relative importance to stability of the four component ligaments of the distal tibiofibular syndesmosis. Eight fresh-frozen cadaver specimens were tested on a hydraulic test system during sequential cutting of the ligaments. The percentage resistance to 2 mm of diastasis was measured for the four ligaments. The anterior inferior tibiofibular ligament provided 35%, interosseous ligament 22%, superficial posterior inferior tibiofibular 9%, and deep posterior inferior tibiofibular 33%. These results have clinical implications with regard to injury. Damage to the syndesmosis should be assessed anteriorly and posteriorly at the time of examination. The interosseous ligament can be visualized arthroscopically.