Morphology of the distal radioulnar joint: cadaveric study with MRI and MR arthrography with the forearm in neutral position, pronation, and supination.

Abstract

The purpose of this study was to evaluate the physiologic extent and thickness of the cartilage and bare areas of the distal radioulnar joint with gross anatomic examination, MRI, and MR arthrography with the forearm in neutral position, maximal pronation, and maximal supination. MRI and MR arthrography were performed on 10 cadaveric specimens (mean age at death, 82.9 years; range, 56-97 years) with the forearm in neutral position, maximal pronation, and maximal supination. Cartilage surface and thickness were assessed, and degenerative changes and bare areas were evaluated in consensus by two musculoskeletal radiologists. Gross anatomic and histologic examinations were used as the reference standard. MRI in maximal pronation and supination was helpful in evaluation of the ulnar cartilage. In the axial plane, any change in cartilage thickness in the ulnar head was related to chondral degeneration. In the coronal plane, cartilage thickness proved to be an unreliable sign in the assessment of chondral degeneration. The presence of osteophytes in the proximal aspect of the joint was easily detected and proved to be a reliable criterion for joint degeneration. Bare areas were found at the proximal and volar attachments of the joint capsule. Detailed knowledge of the anatomy of the distal radioulnar joint should allow more accurate assessment of degenerative changes and localization of erosions in inflammatory joint disease. Imaging with the forearm in maximal pronation and supination can improve visualization of the cartilage of the ulnar head.