Abstract
We adduce the following conclusions from our experience of using this spring-loaded compression screw on completely displaced medial fractures of the femoral neck:
1. That this method probably eliminates non-union when the head is fully viable.
2. That primary "first-intention" osseous union occurs in approximately 33·3 per cent of cases.
3. That a vascular complication, of varying severity, undetectable by orthodox radiological tests, is revealed by extrusion of the screw in 66·6 per cent of cases.
4. That these observations disprove the idea that the main obstacle to revascularisation of an ischaemic head is the existence of forces so inclined to the axis of the femoral neck as to cause "shear."
5. That, compared with the Smith-Petersen nail used for completely displaced fractures, continuous spring compression can materially reduce the incidence of utter mechanical failure within the first year after operation. This is the result of "mushroom" impaction which itself can resist shearing strain and so can permit function as a fibrous union.
6. That early and rapid extrusion is a sensitive indication of a vascular complication in the head. Forewarned by this, activity can be restricted, or possibly other measures adopted, to anticipate or permanently postpone serious trouble.
