It seems right to draw the following conclusions from this study of the relative merits of early and delayed fixation for fractures of the femoral and tibial shafts.

1. In patients under the age of sixty years with femoral shaft fractures there seems to be a significant improvement in the speed and quality of union when internal fixation is delayed. In patients over the age of sixty years the results of delayed fixation are worse than those of early fixation, and in any case the dangers of prolonged recumbency make the latter method preferable.

2. Delaying fixation for tibial shaft fractures does not affect speed of union or functional result. However, the incidence of non-union in these fractures is reduced by over 50 per cent by delaying fixation. This is a good reason for delaying fixation of this fracture too.

Some possible reasons for the improved results after delayed fixation have been discussed.