Arthroscopic, Macroscopic, and Microscopic Anatomy of the Synovial Fold of the Elbow Joint in Correlation With the Common Extensor Origin

The synovial fold belongs to the lateral epicondyle enthesis, which is a composite of the common extensor tendon, undersurface capsule, and bone. Therefore, lateral epicondylitis with degenerative lesions in the area of the common extensor origin may involve the synovial fold and induce hypertrophic changes.