Partially ruptured posterior cruciate ligament causing medial tibiofemoral joint impingement

Impingement syndrome resulting from a partially torn posterior cruciate ligament (PCL) stump has not been reported in the English-language literature. We present 2 cases of impingement caused by the torn stump of a partially ruptured PCL. Both patients suffered from severe knee joint pain during knee flexion over 70 degrees to 90 degrees and medial joint-line tenderness after the injury. Magnetic resonance imaging (MRI) showed the partial rupture of the PCL, mainly in the posteromedial (PM) bundle. In both cases, arthroscopic examination revealed that the rupture of the PCL involved the femoral side of the PM bundle, and the torn stump of the PCL was entrapped in the medial tibiofemoral joint (TFJ). The torn stump was removed completely, and the symptoms improved significantly. Partial ruptures of the PCL occur frequently, and it is anticipated that many patients may suffer from pain arising from impingement of a partially torn PCL entrapped in the medial TFJ. Therefore, studies on this subject should continue.