Discoid lateral meniscus: clinical manifestations and arthroscopic treatment

Discoid lateral menisci are rare in western races but not uncommon among oriental people. This study correlated the clinical manifestations and imaging characteristics of discoid lateral menisci with arthroscopic findings in Taiwanese subjects.

Cases of lateral discoid menisci including 58 knees of 56 patients were retrospectively analyzed. Standard arthroscopic surgery had been performed in 42 knees of 40 patients to confirm the diagnosis. In 41 knees, anomalous menisci were considered to be the cause of symptoms and partial meniscectomies were performed by removing the redundant central portion to fashion a common semi-lunar pattern. Arthroscopic findings were investigated and correlated with the clinical manifestations and findings of magnetic resonance images.

Pain was most frequently the chief complaint but did not necessarily occur in association with a tear of the meniscus. The pain usually began with a minor trauma on the affected knee. Other symptoms included clicking, snapping, locking, and a "tightness", "catching" or "intra-articular foreign body" sensation during motion of the joint. These symptoms were relieved after surgical reshaping of the meniscus of patients. Magnetic resonance imaging identified the anomaly and the existence of a tear, and was especially diagnostic when the tear was confined to the interior. These intra-substance tears were masked by intact external features and overlooked during arthroscopy. The surgical outcomes were followed up using the Ikeuchi scale, yielding results of excellent in 34, good in three, fair in two, and poor in two knees.

Unlike a normal meniscus, pain may exist with an intact discoid meniscus. The symptoms of a discoid meniscus can be relieved effectively by arthroscopic partial meniscectomy.