We undertook this large prospective study of intracapsular fractures treated with internal fixation to evaluate whether the degree of initial fracture displacement correlated to fracture healing complications including nonunion and avascular necrosis. We classified intracapsular fractures based on anteroposterior and lateral radiographs, as undisplaced, partially displaced and fully displaced. In total 878 patients with a non-pathological intracapsular hip fracture included in this study were treated by fixation of the fracture with three cancellous screws. Overall complications of fracture healing were 23.2% for undisplaced, 31.1% for partially displaced and 45.6% for fully displaced fractures showing correlation between fracture displacement and complication rate. The difference between the three groups for the complications of non-union and total fracture healing complications was statistically significant with an increasing complication rate as the fracture became more displaced. Intracapsular hip fractures show a progressive increase in the occurrence of fracture healing complication with increasing degree of initial fracture displacement.

Fractures of the femoral neck (intracapsular hip fractures) constitute a common and expensive injury for health services to manage. Due to the tenuous blood supply to the femoral head and the difficulty in achieving stability after internal fixation, these fractures are associated with the complications of fracture displacement (or re-displacement after reduction and fixation), non-union and avascular necrosis [11]. Previous studies have suggested that the greater the degree of initial fracture displacement the greater the risk is for these fracture healing complications to occur [1,9]. This high risk of fracture healing complications has led to a significant proportion of these fractures being treated with a replacement arthroplasty. For those fractures with no, or minimal, displacement internal fixation is still preferred as this operation is less invasive and allows the patients to retain their own femoral head. The problem remains in how to define the degree of displacement that leads to an unacceptably high risk of fracture healing complications. Current classification methods all concentrate on the appearance of the fracture on the anteroposterior (AP) radiograph [9,15,19], with little consideration of the fracture on the lateral radiograph. A previous description of intracapsular fractures using radiographs and pathological specimens by Per Linton in 1949 [12] described the progressive degrees of displacement that may occur with intracapsular fractures (see Figure 1). This he termed the intermediary fracture pattern. The diagram shows how there may be minimal displacement on the AP radiograph with a range of angulation on the lateral radiograph and hence fragment separation. This study uses a large series of patients with an intracapsular hip fracture all treated by internal fixation, and concentrates on the appearance of the fracture at presentation on both the anteroposterior and lateral radiographs. This, taken in conjunction with the principle that there is a continuous range of degree of displacement of the fracture, was used to subdivide a series of patients into groups of varying fracture displacement and to determine the outcome for these patients with regard to the occurrence of subsequent fracture healing complications following internal fixation. The complication rate in comparison with the measured angulation of the fracture was also assessed.

Alpine
Managing Editor
Journal of Orthopedic and trauma.
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