Posterolateral rotatory instability of the elbow: Usefulness of MR imaging in diagnosis

PURPOSE: To evaluate the efficacy of magnetic resonance (MR) imaging in the assessment of the normal and abnormal ulnar band of the lateral collateral ligament for diagnosis of posterolateral rotatory instability. MATERIALS AND METHODS: In nine symptomatic patients and nine asymptomatic subjects, MR imaging was performed with three-dimensional gradient-recalled and fast spin-echo sequences. The nine patients had clinical symptoms suggestive of subtle elbow instability. RESULTS: The components of the lateral collateral ligament were identified; tears of the ulnar band were noted in all symptomatic patients. The anterior fibers of the lateral collateral ligament, including the annular ligament, were intact. All symptomatic patients subsequently underwent surgical exploration and reconstruction. Positive clinical findings were demonstrated at examination performed while the patients were under anesthesia. All tears of the ulnar band were confirmed. CONCLUSION With use of appropriate pulse sequences, MR imaging is an effective tool in the preoperative, noninvasive diagnosis of posterolateral rotatory instability.