Synovial chondromatosis originating from the synovium of the anterior cruciate ligament: a case report

A case of synovial chondromatosis originating from the synovium of the anterior cruciate ligament (ACL) resulting in a mechanical block to knee extension is reported. A 36-year-old man complained of a restricted range of left-knee motion and pain when walking. Plain roentgenograms showed normal appearance, however, magnetic resonance imaging showed intensity changes in the ACL. Arthroscopically, numerous small free bodies were observed. Proliferation of synovium and cartilaginous tissues were identified around the ACL. There were no significant findings in the synovium except around the ACL. The synovium around the ACL was resected and free bodies were washed out. This is the first report of synovial chondromatosis originating from the synovium of the ACL.