Tensile engagement of the peri-ankle ligaments in stance phase.

BACKGROUND: Development of reconstructive operative procedures to restore normal ankle kinematics after injury requires an understanding of the biomechanics of the ankle during gait. The contribution of the peri-ankle ligaments to ankle motion control is not yet well understood. Knowledge of the tensile engagement of the peri-ankle ligaments during stance phase is necessary to achieve physiologic motion patterns.
METHODS: Eleven fresh-frozen cadaver ankles were subjected to a dynamic loading sequence simulating the stance phase of normal level gait. Simultaneously, ligament strain was continuously monitored in the anterior talofibular, calcaneofibular, and posterior talofibular ligaments, as well as in the anterior, middle, and posterior superficial deltoid ligaments. Eight of these specimens underwent further quasi-static range-of-motion testing, where ligament tension recruitment was assessed at 30 degrees plantarflexion and 30 degrees dorsiflexion.
RESULTS: In the dynamic loading tests, none of the ligaments monitored showed a reproducible strain pattern indicating a role in ankle stabilization. However, in the extended range-of-motion tests, most ligaments were taut in plantarflexion or dorsiflexion.
CONCLUSIONS: A consistent combination of individual ligament strain patterns that principally control ankle motion was not identified; none of the ligaments studied were reproducibly recruited to be a primary stabilizing structure. The peri-ankle ligaments are likely to be secondary restraining structures that serve to resist motion to avoid extreme positions. Stance phase ankle motion appears to be primarily controlled by articular congruity, not by peri-ankle ligament tension.