Stability of the ankle joint. Analysis of the function and traumatology of the ankle ligaments.

The purpose of this study was to elucidate the function of the ligamentous structures of the ankle joint, the traumas in which they may rupture, and the types of instability caused by such ruptures. Most previous experimental investigations on the function of ankle ligaments have been performed on osteoligamentous preparations either by forcing a movement in the joint into more or less well-defined directions and observing the resulting injuries or else by cutting ligaments in various combinations and describing the resulting instability. As a rule, this has been done without inducing the increased mobility by a defined torque and without being able to demonstrate the instability continuously in all degrees of dorsi- or plantar flexion. On the basis of these previous studies, the anterior talofibular ligament appears to limit internal rotation, while its role in adduction of the talus has not been clarified. The calcaneofibular ligament per se does not seem to be a factor in adduction. True, there is not complete agreement in this respect, and a few authors have been able to rupture this ligament in isolation by forced adduction. The posterior talofibular ligament seems to restrict dorsiflexion, and perhaps it plays a role, in conjunction with the calcaneofibular ligament, in adduction when the ankle joint is in dorsiflexion. The anterior tibiofibular ligament, and the distal tibiofibular structures on the whole, are assumed to limit external rotation, but it has not been clarified whether they influence adduction and abduction in the ankle joint. Little has been reported about the individual structures which make up the deltoid ligament, as most authors have not distinguished them from each other. However, in combination with the anterior talofibular ligament, the tibiotalar ligament seems to limit the translatory forward gliding of the talus - the so-called anterior drawer sign - and together they presumably inhibit plantar flexion. It has not been possible to find any description of the function of the intermediate tibiotalar ligament, while the posterior tibiotalar ligament has been reported by one author to inhibit internal rotation. Judging by the literature, the function of the tibiocalcaneal ligament seems comprehensive, since it is reported to limit external rotation, dorsiflexion, as well as plantar flexion. The present investigations were divided into three phases: Phase 1 was concerned with elucidating the correlation of injuries to the lateral collateral ligaments to internal rotatory instability, talar tilt, and the anterior drawer sign.(ABSTRACT TRUNCATED AT 400 WORDS)