Purpose: The etiology of pathological media plica of the knee is unknown. We describe two cases of large, torn medial plicae. The cases help understand the etiology and avoid diagnostic pitfalls.
Case summary: Two patients with medial knee pain and pseudolocking were found to have "bucket-handle" tears of the large medial plicae. The pseudolocking phenomenon was observed arthroscopically in an effort to understand causation.
Discussion: Direct trauma and lateral traction are hypothesized to lead to thickened, pathologic medial plicae. A history of locking usually leads the examiner to look for torn menisci or loose bodies. These cases show that a medial plica with a longitudinal split can behave in a manner that can be mistaken for locking. The mechanism by which this occurs gives insight about the condition's etiology.
Relevance: Present treatment for painful medial plica is physical therapy, occasional corticosteroid injection, and arthroscopic excision when these efforts fail. Based on the evidence from these cases, a reasonable first step after diagnosing a traumatic, painful medial plica might be to selectively strengthen the vastus medialis obliquus.