[The natural history of rupture of the posterior cruciate ligament].

A study has been made in a series of 45 patients, 36 of whom were re-examined and 11 of whom replied to a questionnaire, of the fate of knees that had suffered a rupture of the posterior cruciate ligament which had not had a primary or secondary repair. The follow-up was between 5 and 44 years, with a mean of 15 years. In the 36 who were reviewed, 21 showed an isolated posterior laxity, 8 a postero-lateral laxity and 7 a postero-medial laxity. Even though the posterior cruciate ligament is the strongest ligament in the knee, an isolated rupture of the ligament is often well tolerated after a mean period of adaptation of 12 months. This functional tolerance is remarkable since it allows a return to sporting activity, even at high level. However, the disturbance of the kinematics of the knee resulting from the loss of the posterior cruciate ligament leads, after an average of 25 years, to osteoarthritis, either medial tibio-femoral or generalised depending on the morphological features of the patient. These findings have stimulated us to repair fresh lesions in young persons, especially in the presence of combined lesions but care needs to be exercised about the indications for surgery in chronic laxities during the first year of adaptation.