Intracapsular pressure and hemarthrosis following femoral neck fracture.

The possibility that intracapsular hemorrhage after femoral neck fracture may contribute to avascular necrosis remains controversial. The intracapsular pressure and the amount of blood aspirated from 12 hip joints with acute femoral neck fractures were measured. The total volume aspirated never exceeded 5 cm3 of blood. The intracapsular pressure varied from 0 to 68 mm Hg (average, 28 mm Hg). These findings suggest that preoperative aspiration of the joint is unlikely to influence the vascularity of the femoral head since the volume of the hemarthrosis is small and the measured pressure in the capsule is well below the diastolic blood pressure level.