Recognizing and Managing Posterior Cruciate Ligament Injuries

Physicians may be unfamiliar with posterior cruciate ligament (PCL) injuries because the PCL is injured far less frequently than the anterior cruciate ligament and the injury may have a subtle presentation. Contact sport athletes and persons involved in motor vehicle collisions often are affected. PCL injuries frequently occur in conjunction with damage to other capsuloligamentous structures of the knee. A comprehensive examination of the injured extremity must include evaluation of these and neurovascular structures. PCL-specific examination maneuvers include the posterior drawer test, posterior sag test, and quadriceps active test. The primary evaluation should include plain radiographs and MRI. The available data encourage nonoperative management for most grade 1 and 2 injuries, but isolated acute grade 3 injuries may require surgery. (J Musculoskel Med. 2012;29:106-111) Physicians often are familiar with the clinical presentation and management of collateral ligament and anterior cruciate ligament (ACL) strains or ruptures because these injuries occur somewhat frequently in active persons. They may be less familiar with injuries of the posterior cruciate ligament (PCL), an important stabilizer of the knee. The PCL is injured far less frequently, and when it is disrupted in isolation the injury may have a subtle presentation that can elude even the experienced examiner. In addition, patients who sustain isolated PCL injuries may continue to function at a competitive level, symptoms may not develop until long after the inciting event, and the natural history of the isolated PCL-deficient knee remains unclear. Recent biomechanical investigations have demonstrated that the PCL makes a major contribution to knee function and have suggested that chronic posterior instability may result in premature arthrosis. Therefore, the examining physician needs to arrive at a timely and accurate diagnosis and can do so by recognizing the common injury mechanisms and presenting symptoms and initiating the appropriate workup. Current treatment guidelines suggest that low-grade PCL injuries may be managed without surgery and that most patients return to their preinjury function level. However, substantial controversy surrounds what constitutes optimal management of patients who sustain high-grade isolated PCL injuries. There is a paucity of data demonstrating that surgical intervention significantly alters long-term objective or subjective outcomes in this patient cohort. In this article, we focus on familiarizing treating physicians with the mechanisms typically associated with PCL injury and the clinical evaluation of patients in whom PCL insufficiency is suspected. We also provide a discussion of the most current treatment options and a relevant algorithm predicated on existing data about nonoperative and surgical interventions. ANATOMY The PCL originates from the lateral border of the medial femoral condyle (MFC) and inserts about 1 cm below the joint line in a midline depression between the posterior aspects of the medial and lateral tibial plateaus. The ligament consists of 2 functional bundles: the anterolateral fibers are larger in cross-sectional area and tighten in knee flexion and become lax in extension; the posteromedial fibers are smaller and become tight in knee extension and deep knee flexion. Together, the anterolateral and posteromedial bundles act as the primary restraint to posterior translation of the tibia; the collateral ligaments and the posterolateral structures act as secondary restraints. Of note, the PCL is a secondary restraint to abnormal external rotation of the tibia in the setting of injury to the posterolateral structures of the knee.1 AT-RISK POPULATIONS AND MECHANISM OF INJURY Two distinct patient populations are affected by PCL injuries: contact athletes and persons subject to high-energy trauma. The mechanism of injury, magnitude of ligament disruption, and time to presentation may vary greatly between these cohorts.