A review of the English language literature establishes athletic mishaps as a major cause of posterior cruciate ligament injury. However, diversity of opinion exists regarding the functional significance of the lesion, its occurrence as an isolated entity, and the roles of conservative and surgical management. The posterior cruciate ligament is a composite structure, consisting of a superficial tibiofemoral and meniscofemoral portion and a deep tibiofemoral portion. The structure is intra-articular but extrasynovial, coursing from its attachment to the lateral surface of the medial femoral condyle posteriorly and inferiorly to its distal attachment into the posterior rim of the tibia, blending with the capsule and periosteum. Mechanical studies have demonstrated that abnormal posterior tibial displacement can occur only with posterior cruciate ligament laxity. The most prevalent mechanism resulting in injury to the posterior cruciate results from a blow on the anterior aspect of the flexed knee. However, both hyperflexion and hyperextension as well as deceleration and rotation have been described. Posterior cruciate ligament insufficiency may result from an avulsion fracture involving the ligament-bone insertion of the ligament, usually from the posterior aspect of the proximal tibia. Also, disruption may occur as an intersubstance tear of the ligament, either as an isolated phenomenon or in combination with multiple ligamentous injuries. The importance of distinguishing between combined injuries associated with significant collateral and/or anterior cruciate ligament injuries from the 'isolated' type lies in the fact that the prognosis for the 'isolated' injuries is much better. Careful clinical evaluation of the knee with an acute posterior cruciate ligament injury will reveal subtle, but definite, findings peculiar to the lesion. These include the posterior sag sign, the posterior drawer sign, reverse pivot shift, Godfrey's test, and the presence of varus or valgus instability with the joint in full extension. In patients with chronic posterior cruciate ligament laxity, the presenting symptom is often that of patellar pain. It is generally agreed that avulsion fractures involving the ligament-bone insertion of the posterior cruciate ligament should be treated by open reduction and internal fixation. Surgical treatment of this lesion will result in excellent functional recovery. A variety of procedures have been reported for the management of acute disruption of the posterior cruciate ligament.(ABSTRACT TRUNCATED AT 400 WORDS)