Medial plica in patients with knee osteoarthritis: a histomorphological study

The gross appearance and histological features of the medial plicae removed from 48 consecutive patients who had received total knee replacement for severe medial compartment osteoarthritis of their knees were investigated prospectively. The prevalence of the medial plica was 100%. A small branch of skeletal muscle originating from articularis genu inserting into the proximal synovial stroma of the medial plica was found in all knees. The synovial fold of the distal part of the medial plica was disclosed to have a close relationship with the gracilis tendon sheath. Histologically, the majority of advanced pathologic presentation was found at the middle and distal portion of the medial plica that might abrade on the articular cartilage of the medial femoral condyle. Noticeable cartilaginous lesion was found on the facing medial femoral condyle in all knees. The histomorphological findings of the medial plica imply the close interplay between this structure and the medial femoral condyle that might play a role in the pathogenesis of medial compartment osteoarthritis of the knee. Clinical relevance: The findings of this study support the beneficial effect of some surgical procedure that would remove the pathologic medial plica for the treatment of medial compartment OA knee.