Clinical features and prognosis of discoid medial meniscus.

PURPOSE: To evaluate the clinical manifestations and the outcome of surgical treatment of discoid medial meniscus.

METHODS

Records of 13 patients with discoid medial meniscus were retrospectively reviewed for their epidemiology, clinical manifestations, operation methods, treatment outcome and radiographic characteristics.

RESULTS

The 13 cases of discoid medial meniscal injury took up 1.5 ‰ of the overall meniscal injuries treated at our institute during the 44-year period. Patients presented with knee pain (13 patients), giving away (10 patients), swelling (9 patients) and snapping (9 patients). The most common physical signs were medial joint line tenderness (13 patients) and positive McMurray test (11 patients). Ten patients required total meniscectomy. There were excellent short-term results: the median Tegner score was 7, and the mean Lysholm score was 94.8 ± 2.4 at two-year follow-up. However, the long-term outcome was not as good with degenerative changes in the medial compartment of all the involved knees.

CONCLUSION

The discoid medial meniscus is extremely rare. The clinical signs and symptoms of discoid medial meniscal injuries are similar to those of any other meniscal injury. No Wrisberg-ligament type abnormality was found. Meniscectomy for discoid medial meniscus produced promising short-term results and deteriorating long-term results with secondary degeneration of cartilage in the medial compartment.

LEVEL OF EVIDENCE: Retrospective case series, Level IV.