LOW-ANGLE FIXATION IN FRACTURES OF THE FEMORAL NECK

Abstract

The successful management of femoral neck fractures is obviously based upon many factors. The forces acting upon the proximal end of the femur are believed to be mainly compressive in nature, and the low-angle nail by stabilising the fully reduced fracture in the line of these forces is held to allow weight bearing to take place. Low-angle nailing is believed to offer many advantages over conventional methods of treatment but only in the presence of stability. Stable reduction is the essential preliminary to any form of treatment, and low-angle fixation with early weight bearing in the absence of stability is regarded as futile. It is suggested that those subcapital separations which follow trivial injury may originate as stress fractures accompanying the process of bone remodelling in the aged, and that many of these fractures may remain unrecognised and heal spontaneously. With rare exceptions, subcapital fractures are regarded as being of the same essential pattern, and their varying radiological appearance is considered to be due to the different degrees of displacement to which they have been subjected. A new classification based on this premise has been suggested. In a series of eighty subcapital fractures the incidence of avascular necrosis was not adversely affected by early weight bearing, but reduction in the extreme valgus position was invariably followed by this disaster. This is probably also true of any malposition in extreme rotation which must stretch and obliterate the vessels in the ligamentum teres. A rough alignment index of reduction was found to provide an almost infallible guide to the prognosis both in regard to union and to avascular change. It may therefore be possible to base prognosis on the quality of reduction before the fixation appliance has been inserted. The unsatisfactory results in those cases apparently destined to non-union or avascular necrosis may then be avoided by alternative means of treatment at an early stage. Whether this will prove to be true must depend upon a much longer experience of low-angle fixation, and, in common with almost every communication on this subject, premature publication must largely offset the value of the present findings.