Injuries to the posterior cruciate ligament: diagnosis and treatment of early injuries and reconstruction of late instability.

Division of the posterior cruciate ligament in amputation specimens enables one to classify injuries as: (a) isolated posterior cruciate ligament injuries with or without damage of the posterior capsule; or (b) injuries of the posterior cruciate ligament plus lateral and/or medial structures which may be associated with stretching or tearing of the anterior cruciate ligament. The mechanism of injury to the posterior cruciate ligament is by: (a) anteroposterior force on the front of the flexed knee; (b) hyperextension of the joint; (c) posteriorly directed rotatory injuries. Early diagnosis is essential and may require general anesthesia to elicit the posterior drawer sign, and to accurately assess the other ligamentous and bony structures. Chronic injuries can be repaired by using the tendons of gracilis and semitendinosus.