The anterior tibio-talar ligament: one reason for anterior ankle impingement.

The purpose of this study was the evaluation of the ankle's anterolateral ligament structures. We documented the anatomic situation of the ankle's anterolateral ligament structures in 33 Thiel-embalmed specimens. The ligaments had been isolated. We performed measurements on both length and orientation and additionally classified the ligaments. We also conducted histologic tissue staining. We were able to document a regular appearance of a so far not well-realized structure between the talus and the tibia, present in 26 (79%) specimens. Average length of this structure was 26 mm (in 20 degrees plantarflexion). The angular orientation in relation to the ant. tibio-fibular lig. was on average 43.7 degrees. This structure could be classified as being either isolated or widespread, with a further four sub-classifications for the orientation. Histologic staining showed parallel orientated dense collagen fibers as well as elastic fibers and hyaline cartilage in different stages of proliferation. In addition, there were neural fibers in the perivascular and the soft tissue. The histologic findings proved that the structure was a ligament. Since the ant. tibio-talar lig. is constantly present in most ankle joints, it could be considered as a regular finding. Its morphology and histology show that this ligament is loaded under tension as well as under compression. This could be one reason for anterior ankle impingement.