Hegemann’s disease and fishtail deformity: aetiopathogenesis, radiographic appearance and clinical outcome

PURPOSE A systematic review regarding clinical studies on Hegemann's disease and fishtail deformity was performed with the aims to: (1) formulate the most up-to-date theory on aetiology in order to better define these conditions, (2) summarise the most frequent radiographic descriptions on radiographs and (3) give an overview of different treatment options. METHODS A systematic review of studies to date on Hegemann's disease and fishtail deformity was performed. Studies were eligible if: (1) the article provides a description of Hegemann's disease or fishtail deformity, (2) original data of at least one patient was available, (3) the article was written in English, German or Dutch and (4) a full manuscript was available. Animal studies, reviews and expert opinions were not included. RESULTS We included a total of 22 articles: seven regarding Hegemann's disease including eight patients and 15 regarding fishtail deformity including 58 patients. CONCLUSIONS Fishtail deformity and Hegemann's disease seem to be a spectrum of vascular disorders of the distal humerus, varying from a benign mild vascular disorder to a complete avascular necrosis after fractures. Additional imaging is advised to confirm the presence of a fishtail deformity, intra-articular loose bodies and signs of osteoarthritis to decide if, and what, operative treatment is needed. As long as no clear aetiology for both diseases exist and the clinical symptoms and radiographic appearance are difficult to distinguish, both entities should preferably be named as 'vascular disturbance of the trochlear growth plate' to overcome confusing definitions and discussions.