Fishtail deformity of the distal humerus: a report of 15 cases.

BACKGROUND: Osteonecrosis of the humeral trochlea is an uncommon but challenging complication of pediatric elbow fractures. The purpose of this investigation was to characterize the clinical and radiographic presentation of fishtail deformity and outline a treatment algorithm.

METHODS: Fourteen patients were treated at a tertiary children's hospital between 1995 and 2010. Mean age at presentation was 10 years (range, 2.5 to 12 y). Demographic, clinical presentation, radiographic, and treatment data were recorded. Mean follow-up was 3.9 years from recognition of fishtail deformity (range, 0.5 to 7.2 y).

RESULTS: Average time from index injury to presentation of fishtail deformity was 4.7 years (range, 0.5 to 9 y). Twelve patients (80%) presented with pain and mechanical symptoms. Seven patients were initially treated with observation, of whom 2 eventually underwent arthroscopic debridement. Ultimately 7 patients underwent arthroscopic and 1 open debridement and loose body removal; 5 of these patients required further surgery for recurrent mechanical symptoms. One patient underwent arthroscopic debridement and epiphysiodesis to maintain radiographic alignment. After initial arthroscopic debridement, 6 of 7 patients (85%) had pain relief, and all patients demonstrated improved range of motion and/or relief of mechanical symptoms. At most recent follow-up, 6 patients (40%) had persistent pain, and only 2 (13%) had normal elbow motion. Four of the 5 patients who lost 20 or more degrees of extension had radial head subluxation or dislocation. The remaining 9 patients had a reduced radiocapitellar joint. Loss of extension in those with and without subluxation of the radial head was 32 and 6 degrees, respectively.

CONCLUSIONS: Fishtail deformity is a rare but vexing complication of pediatric elbow fractures. Clinical presentation with loss of motion and/or pain is often delayed. Arthroscopic debridement may improve symptoms in the short term, but long-term prognosis is guarded. Subluxation of the radial head is associated with worse functional results. Early detection and surgical strategies to prevent proximal migration of the forearm and development of ulnotrochlear incongruity, radial head dislocation, and impingement may improve outcomes in patients with fishtail deformity.