Functional anatomy of the medial collateral ligament of the ankle joint

The calcaneotibial and posterior talotibial ligaments slacken and the naviculotibial ligament tightens as the ankle plantarflexes; the reverse occurs in ankle extension. The naviculotibial ligament increases its length and the posterior talotibial ligament relaxes in abduction. The cutting of the posterior talotibial ligament repercutes on other parts of the medial collateral ligament. The cutting of other parts of the medial collateral ligament produces very little change on the posterior talotibial ligament. When the whole medial collateral ligament is severed, there is a lateral displacement of the talus. This may be important in the diagnosis and surgical treatment of a torn medial collateral ligament.