INTRACAPSULAR HIP PRESSURE AFTER FEMORAL-NECK FRACTURE

A consecutive series of 34 patients with femoral neck fractures was in cluded in a prospective study aimed at evaluating preoperative variati ons in intracapsular pressure after changes in hip position, hip tract ion, and aspiration of hemarthrosis and their influence on the develop ment of femoral head necrosis, Patients were observed for 7 years afte r surgery, Before aspiration, the mean intracapsular pressure in the a ntalgic physiologic position was 44.4 mm Hg, There were no differences between displaced and undisplaced fractures, The pressure was a maxim um (mean value, 124.8 mm Hg) with the hip in extension and inward rota tion, this pressure being greater than the blood systolic pressure in most cases, Hip traction of 3 kg in the antalgic physiologic position was found to be highly effective in preventing any bone flow tamponade effect in displaced and undisplaced femoral neck fractures: the mean intracapsular pressure decreased to 28.5 mm Hg. Aspiration of the hema rthrosis induced a significant decrease in intracapsular pressure only in cases with impaired vascularity of the femoral head as measured by scintigraphy using Tc-99m labeled methyldiphosphonate. Aspiration of the hemarthrosis therefore is indicated only in the above cases, altho ugh it is less effective than hip traction in the antalgic position, T here was no significant correlation between intracapsular pressure and the scintigraphy ratio, Avascular necrosis of the femoral head was de tected in six cases, Among these, five patients had an intracapsular p ressure below their diastolic blood pressure, This could indicate that vascular damage related to the fracture could be an important cause o f bone necrosis despite that blood supply can be decreased by a tampon ade effect.