The current standard for treatment of humeral shaft fractures is in a functional humeral brace. Aims: To further assess the union rate for this mode of treatment and to delineate and any fracture type less likely to go on to union.

Retrospective radiographic and clinical review of 199 consecutive acute adult humeral shaft fractures. 43 operated on acutely (including all open fractures). Remaining 156 fractures treated in a humeral brace. Non union was determined as delayed fracture fixation or no evidence of union at 1 year. Union rate 82.9% with 88.5% follow-up. 16 of the 24 non unions were proximal third (all but one spiral/oblique): 71.4% union rate. Middle third fractures 87.3% and distal third shaft fractures 88.9 % union rate. Union rate of fractures with 3+ parts inclusive of all regions of the shaft was 95.6%.

The union rate in this study is not as high as has previously been reported for functional brace treatment. A lower threshold for intervention in proximal third spiral/oblique humeral shaft fractures may be indicated. Fracture site comminution is a very good prognostic indicator.