Impinging exostoses of the proximal radius: a report of two cases with distinct clinical features.

Owing to the rotatory motion of proximal radius and the closely apposed anatomic structures, cortically based osseous lesions at the level of the proximal forearm may produce symptomatic impingement. While osseous impingement onto the adjacent proximal ulna may result in limited forearm rotation, impingement on the surrounding soft-tissue structures may produce symptoms as well. Here, we describe two cases of symptomatic proximal radius exostosis, each of which produced distinct clinical symptoms. In the first case, impingement on the posterior interosseous nerve produced symptoms of radiating forearm pain and paresthesia resembling radial tunnel syndrome. In the second case, impingement of the exostosis on the distal biceps tendon resulted in painful mechanical snapping with rotation of the forearm. In both cases, symptoms rapidly improved after surgical excision.