There is a 5 mm erosion of the periosteum and cortex on the medial aspect of the distal radial metaphysis just proximal to the distal physis. The eroded bone is slightly sclerotic which is suggestive of a chronic process. There is negative ulna variance and the epiphysis of the shortened ulna is located adjacent to the eroded portion of the radius. The appearances are consistent with ulna impingement syndrome.