Abstract
Arthroscopy sometimes reveals cases with hypermobile lateral meniscus which appears to cause internal derangement of the knee joint. As there is as yet no definitive concept of a hypermobile lateral meniscus, the diagnosis and treatment of it are likely to be difficult. We have experienced 12 knees in 10 cases with hypermobile lateral meniscus which were confirmed by arthroscopy. Stabilizing surgery was performed for lateral meniscus repair under arthroscopy in 9 knees (7 cases), while the remaining 3 knees (3 cases) were left untreated.
The onsets were in the higher grades of elementary school and in junior and senior high school, and most cases had bilateral involvement. Only one case had an apparent history of injury of the knee, and the others were thought to be non-traumatic. The main symptoms were locking and catching of the joint, while general joint laxity was present in 6 cases. Arthrography and arthroscopy did not show any abnormality in the ACL, PCL, or medial meniscus, and did not reveal patella dislocation, patella subluxation, or discoid meniscus. Under arthroscopy, abnormal hypermobility of the lateral meniscus was recognized, strongly indicating a weak connection between the posterior portion of the lateral meniscus and the coronary ligament and the popliteus muscle. Satisfactory results were obtained in the cases which were treated by stabilization of the lateral meniscus using arthroscopy.
