Pictorial review: ‘Fishtail deformity’ of the elbow

Fishtail deformity of the elbow is characterised by a contour abnormality of the distal humerus, which develops when the lateral trochlear ossification centres fails to develop or resorbs. It is an uncommon complication usually following a distal humeral fracture in childhood. Whilst initially presumed to be a benign condition, long-term follow-up suggests that patients with fishtail deformity are prone to functional impairment, ongoing pain and the development of early osteoarthrosis. This paper reviews the imaging findings in fishtail deformity, the proposed aetiology and the potential long-term complications.