Pictorial review: ‘Fishtail deformity’ of the elbow

Abstract

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.

Hegemann's disease and fishtail deformity: Aetiopathogenesis, radiographic appearance and clinical outcome

“…The lateral aspect of the medial crista, the trochlear groove and the trochlear apex are relatively hypovascular. So those structures are prone to disturbances in the blood supply and the development of avascular necrosis [ 4 ]. Trochlear avascular necrosis is characterised by disturbance of growth involving the centres of ossification of the trochlea.…”

“…Trochlear avascular necrosis is characterised by disturbance of growth involving the centres of ossification of the trochlea. Therefore, fishtail deformity could be a result of avascular necrosis of the vessels supplying the lateral trochlea [ 4 , 28 ]. If the lateral trochlear ossification centre development is disturbed and the remaining normal physis continues to grow, the distal humerus assumes a typical V shape: the fishtail [ 4 , 21 ].…”

“…Hegemann’s disease is often diagnosed by radiography months or years after trauma [ 7 , 10 , 29 ]. This makes Hegemann’s disease prone to confusion with a ‘fishtail deformity.’ Fishtail deformity of the elbow is an uncommon complication usually following a distal humeral fracture in childhood [ 4 ]. Usually, the term ‘Hegemann’s disease’ is used for spontaneous or idiopathic osteonecrosis of the humeral trochlea.…”

“…Reports on patients with Hegemann’s disease are very rare [ 2 ]. Fishtail deformity of the elbow is a rare complication after fracture of the distal humerus, usually following a supracondylar, a lateral condyle, a medial condyle or even after Salter–Harris type I epiphyseal fractures in childhood [ 4 ].…”

Gull‐wing sign: Acetabular fracture

“…In children, another fracture gives rise to an animal sign. A fracture of the distal humerus in a child can produce a fishtail deformity . A supracondylar or condylar fracture can result in osteonecrosis of the epiphysis of the trochlear.…”