Clinical study on internal fixation of femoral neck fractures.

A clinical study on the results of internal fixation of femoral neck fractures treated by multiple Knowles pinning was undertaken and correlated with the results of an experimental study. Experimentally, failures were produced by downwards migration of the Knowles pins. This phenomenon accounts for the settling of the femoral head on the neck and the frequency of non-union or malunion in patients with subcapital fractures. The type of fracture, type of reduction and age correlate with failure rate. This has to be explained by biomechanical considerations based upon the mode of failure of the internal fixation. A Garden stage III and IV, a varus or anatomical reduction of the fracture and an old age predispose to failure of the internal fixation and consequent non-union.