Abstract
A knowledge of the incidence of fractures through metastases of various sizes in long bones is important when considering prophylactic internal fixation. The notes and X-rays of 66 consecutive patients with 100 metastases in long bones were analysed. Fractures are highly unlikely to occur (2.3 per cent) when less than 50 per cent of the cortex is destroyed but likely (60 per cent) when 50–75 per cent of the cortex is destroyed and most likely to occur (80 per cent) when over 75 per cent of the cortex is destroyed.