Locked knee caused by intraarticular ganglion.

Intraarticular ganglion cyst arising from the cruciate ligament is difficult to diagnose by clinical symptom. In our case, Cyst attached anteriorly to posterior cruciate ligament, and limited both flexion and extension of knee. The cyst was excised in a piecemeal fashion arthroscopically. Knee pain and limitation in knee motion disappeared by the day after surgery. We hypothesize that reason of restriction of extension is impingement between anterior cruciate ligament and intracondylar, and reason of restriction of flexion is stimulation nerve ending in the synovial membrane stretched with knee motion.