To evaluate the efficacy of physical examination and dynamic arthroscopy in the diagnosis and treatment of medial patellar plica syndrome which is likely to be overlooked.

23 cases diagnosed as medial patellar plica syndrome from August 1998 through December 1999 were evaluated. Diagnosis was made by a symptom of a pain and a click sound during knee flexion, a physical examination of mass palpation and dynamic arthroscopy.

A dynamic rotation test was an useful physical examination having 96% rate of sensitivity. The results of excellent and good cases were in 19 cases (83%) and there was no worsened case symptomatically after arthroscopic resection. Postoperative complications were 3 cases including incomplete excision (1 case), postoperative hemarthrosis (1 case) and medial meniscus instability due to incorrect arthroscopic technique (1 case). In patients younger than 30 year old, the result of arthroscopic excision was better than that in older ones.

Careful physical examination with dynamic arthroscopy is a useful method to diagnose the medial patellar plica syndrome which is likely to be overlooked, and arthroscopic complete excision result in excellent results which is of benefit to fast rehabilitation.