Mucoid degeneration of the anterior cruciate ligament: MRI, clinical, intraoperative, and histological findings.

PURPOSE

To describe the clinical, MRI, intraoperative, and histological features of mucoid degeneration of the anterior cruciate ligament (ACL).

METHODS

This study included 10 patients (average age 47 years, range 19-69 years) who underwent surgery due to clinical diagnoses of mucoid degeneration of the ACL. All patients underwent preoperative magnetic resonance imaging (MRI) and were arthroscopically treated.

RESULTS

All 10 patients reported preoperative posterior knee pain. MRI indicated a thickened ACL with increased signal on all sequences. Postoperatively, only six of 10 patients were confirmed by biopsy to have a mucoid degeneration of the ACL. An associated intraosseous tibial cyst or ganglion was observed only in patients with a definitive diagnosis of mucoid degeneration.

CONCLUSIONS

Mucoid degeneration of the ACL can be suspected in patients with posterior knee pain associated with a thickened ACL. Associated findings such as an intraosseous tibial or ganglion cyst help to rule out differential diagnosis.