Enthesitis and related changes in the knees in seronegative spondyloarthropathies and skin psoriasis: magnetic resonance imaging case-control study.

Objective: To describe enhanced magnetic resonance imaging (MRI) features and characteristic entheseal changes in the knees in patients with seronegative spondyloarthropathy (SpA).

Methods: The 56 patients included 30 with psoriatic arthritis, 5 with ankylosing spondylitis, 5 with reactive arthritis, 5 with ulcerative colitis (UC), 5 with Crohn's disease, and another 6 with skin psoriasis. Controls were 20 healthy subjects without knee complaints.