Hip joint pressure after femoral neck fracture

The hip joint pressure in 40 patients with intracapsular femoral neck fractures was measured on the fracture table prior to surgery. All but 1 patient had pressures well below 20 mmHg with the hip unreduced. When the hip was extended and internally rotated, the pressure rose to values exceeding the normal arteriolar pressure in most patients, with a peak pressure of 135 mmHg. In nine of 22 Garden IV fractures, the pressure remained low despite extension and inward rotation. Injection of contrast medium in three of these hips indicated a rupture of the joint capsule. The pressure response to extension and internal rotation was less marked in fractures older than 72 hours. The findings do not support the hypothesis that a hip-joint tamponade is a common etiologic factor for the development of femoral head necrosis following fracture. However, prolonged reduction maneuvers with the hip joint in extension and internal rotation can create intracapsular pressures high enough to temporarily jeopardize the circulation of the femoral head.