Symptomatic calcification of the anterior cruciate ligament: A case report.

We report a rare case of symptomatic calcification of the ACL. A 31-year-old man complained of severe knee pain with restriction of knee motion from 30° to 130° for a week. Plain radiographs and multi-planar CT revealed calcification within the intercondylar notch with no osteoarthritic changes. MRI revealed a low signal intensity mass near the intact ACL. The ACL appeared bulged by arthroscopy and white and creamy fluid exuded from the partially excised synovial membrane. Pain subsided immediately postoperatively. Histologically, the calcific deposit near the ACL showed negligible degenerative changes and resembled calcifying tendinitis of the rotator cuff. Although calcific deposits rarely affect the knee joint, calcification of the ACL should be included in differential diagnoses for acute knee pain and restricted range of motion such as mechanical locking. This case illustrates that arthroscopic removal of the deposits can be effective.