Salomon Blutreich, Presenter: Nothing to Disclose

Mark E. Schweitzer MD, Abstract Co-Author: Nothing to Disclose

Zehava Sadka Rosenberg MD, Abstract Co-Author: Nothing to Disclose

Pseudodefect of the capitellum, located in the distal humerus, is a well-known MRI interpretation pitfall, not to be confused with the anteriorly located osteochondritis dissecans. However, we have noted true traumatic lesions in the posterolateral humerus and sought to describe their MR appearance and any associated findings which may divine their presumed mechanism.

781 elbow 1.5T MR examinations, performed over 42 months, were reviewed for marrow abnormalities in the posterolateral humerus. If present, two reviewers noted: a) location and pattern of the lesion, b) associated medial collateral (MCL), and lateral ulnar collateral (LUCL) ligament injuries, d) other areas of osseous abnormalities, e) medical history.

There were 46 (5.9 %) cases with marrow edema in the lateral humerus. Nine posterolateral cases (19.6%) were included and were classified as crescentic, n=3; wafer like, n=1; and bruise-like, n= 5. All but 2 had visible LUCL injuries with 1 (with the most extensive bruising) also having an MCL injury There were 5 associated radial head bruises, 4 of these also had coronoid process bruises, and 1 also had an olecranon bruise. Falls were causative in 5; 2 had documented dislocation; and 4 had posterolateral rotatory instability on physical exam.

Contrary to current concepts, and albeit infrequently, traumatic lesions can occur at the posterolateral distal humerus. These lesions are often associated with LUCL injury, may be seen following elbow subluxation, and may be an osseous window into posterolateral rotatory instability.

Blutreich, S, Schweitzer, M, Rosenberg, Z, Lesions of the Distal Humerus and Posterior Capitellum: Not Always a Pseudodefect.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4406460.html