Annular ligament of the elbow: MR arthrography appearance with anatomic and histologic correlation.

ABSTRACT

OBJECTIVE: As part of the lateral ligament complex of the elbow, the annular ligament has an adjunctive role in stabilizing the proximal radioulnar joint. Knowledge of the anatomy of this ligament may enhance our understanding of its functional role in maintaining integrity of the elbow joint in fracture and dislocation. The purpose of this study is to provide a detailed analysis of the anatomy of the annular ligament using MR arthrography with anatomic and histologic correlation in cadavers. MATERIALS AND METHODS: MR arthrography of six fresh cadaveric elbows using coronal, axial, and sagittal planes was performed after injection of intraarticular contrast material. The MR arthrography appearance of the annular ligament was correlated with anatomic sectioning and histologic analysis. RESULTS: On MR arthrography, the axial and sagittal planes provided the best evaluation of the annular ligament. Although the anterior attachment of annular ligament was a single band, the posterior attachment was fenestrated in two of six specimens. Anatomic inspection confirmed the MR observations. On histology, the annular ligament appeared to be part of a complex supporting structure continuous with the elbow joint capsule, adjacent ligaments, and muscles. CONCLUSION: The annular ligament is a complex structure formed from the capsule, lateral collateral ligamentous complex, and supinator muscle that act in unison to stabilize the proximal radioulnar joint. Its posterior attachment to the ulna can be fenestrated normally. A detailed analysis of anatomy of this ligament allows us to better understand its functional role in fractures and dislocations of the elbow joint.