Management of the PLC Injury

Posterolateral complex injury (PLC): The incidence of the PLC was reported to be 5.8–16% among knee ligament injuries. According to Delee et al. and Laprade et al., the isolated PLC injury was about 1.6–2.1% of the knee ligament injuries. Most of the PLC injuries are associated with cruciate ligament injuries, especially combined PCL, 80–83% more. To avoid neglect of the PLC injury, the physician should have a high suspicion and routinely physically examine the PLRI and take history carefully. PLRI is identified as posterolateral subluxation and external rotation of the lateral tibial plateau in relation to the lateral femoral condyle as a consequence of injury to structures of the PLC of the knee. It is easy to miss PLRI and also the difficulty of relying on physical examination for the diagnosis of PLRI; no objective quantitative test exists for assessing increased external rotation. This makes an accurate diagnosis of PLRI difficult. The physician should check the reduced position of the medial tibial plateau to the femoral condyle as normal and then check PLRI or not; otherwise, it easily leads to misdiagnosis, especially in PCL with PLRI combined cases. The most common cause of the failure of the cruciate ligament reconstruction, especially PCL reconstruction, is neglected PLRI. Most of the PLC injuries are associated with cruciate ligament injuries; 43–80% (Hughston 1976), 59% (Baker 1983), 65% (DeLee 1983), and 80% (Hughston and Jacobson 1985). To avoid neglect of the PLC injury, the physician should have a high suspicion and routinely perform a physical examination of PLRI and take history carefully. Take a history about varus and hyperextension injury, tenderness, and ecchymosis around the knee, and also check gait, especially for varus thrust gait or not. In a cadaver study, sectioning the PLC increased in situ force in the PCL 2–6 times, and the PCL with PLC cut resulted in 21 * external rotation and 14* varus rotational instability increase, but in isolated PCL loss, there is a small amount of the rotatory or varus and valgus laxity. PLRI is identified as posterolateral subluxation and external rotation of the lateral tibial plateau in relation to the lateral femoral condyle as a consequence of injury to structures of the PLC of the knee. It is easy to miss PLRI and also the difficulty of relying on physical examination for the diagnosis of PLRI, and no objective quantitative test exists for assessing increased external rotation. This makes accurate diagnosis of PLRI difficult. As is known, a positive dial test may result from either posterolateral or medial knee injuries, and the results of rotatory instability tests should be carefully interpreted.