Internal derangement of the knee joint due to pathologic synovial folds: the mediopatellar plica syndrome.

A prospective study of the mediopatellar plica was performed by arthroscopy in 134 patients. The mediopatellar plica is a fold of synovial tissue attaching medially at the undersurface of the quadriceps tendon which extends distally around the patella and over the medial femoral condyle to insert into the fat pad. Extensor mechanism derangement may be produced by a mediopatellar plica when it loses its pliability owing to fibrosis or hyalinization. Persistent disabling symptoms require surgical treatment consisting of excision by arthrotomy or by operative arthroscopy.