Anatomy of the tibiofibular syndesmosis and its clinical relevance.

The purpose of the present study was to describe the anatomical structure of the tibiofibular syndesmosis. Dissection of the tibiofibular syndesmosis was performed on 30 cadaveric specimens of the ankle in adults. The stability of the tibiofibular mortise is ensured by three ligaments. The interosseous tibiofibular ligament forms a spatial network of fibers of a pyramidal shape filled with fibrofatty tissue. The anterior tibiofibular ligament consists of three parts: the upper one is the shortest, the medial one is the strongest and the lower part is the longest and the thinnest. The posterior tibiofibular ligament is a strong, compact ligament the lower margin of which literally forms the articular labrum for the lateral ridge of the trochlea of the talus. The so-called inferior transverse tibiofibular ligament, as this part of the ligament is sometimes characterized, cannot be considered as a separate ligament. Direct contact between the distal tibia and the fibula was found in 23 cases. Contact facets which were covered with articular cartilage were very small and located in the anterior half of the tibiofibular contact line. In the posterior part of the tibiofibular contact line a vertical V-shaped synovial plica attached by its lateral aspect to the fibula dipped between the two bones. In seven cases where there was no direct contact between the two bones this plica extended anteriorly to the anterior tibiofibular ligament. The findings show that in three quarters of cases the connection of the distal tibia and fibula is not a mere syndesmosis but also a synovial joint. The presented facts change traditional opinions on the structure of the tibiofibular syndesmosis and they should be reflected in the treatment of dislocation-fractures of the ankle as well as in case of so-called anterolateral ankle impingement.