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Computed tomography was performed on 40 patients with recent hip trauma. Radiographs of 25 showed a fracture of the femoral neck with slight displacement; 24 of these had intra-articular fluid and 20 had a lipohaemarthrosis on the CT scan. In 15 patients, radiographs at the time of admission were normal but suspicion of fracture remained. A fracture was later verified in five patients, four of whom had lipohaemarthrosis on admission. In the remaining 10 patients no fracture could be detected; only one patient had a hip joint effusion but no free fat. Thus all 24 patients with lipohaemarthrosis had an intracapsular fracture of the hip. We suggest CT for patients with hip trauma and negative radiographs. The presence of a lipohaemarthrosis of the hip strongly suggests an intra-articular fracture of either the femoral neck or the acetabulum.

In eight undisplaced intracapsular fractures of the femoral neck, an intracapsular hematoma was diagnosed by computed tomography. 99mTc-MDP scintimetry revealed markedly reduced or absent blood supply to the head of femur. The intracapsular pressure was 23 (2.7-43) kPa with the hip in neutral position. Following aspiration of 12 (0.5-36) ml of blood, pressure was reduced to zero, and postaspiration scintimetry revealed restitution of blood supply to the femoral head. Hip joint tamponade in these patients has caused femoral head ischemia, reversible by aspiration.

In 34 femoral neck fractures, CT was performed within 1-32 days after internal fixation. All the cases except one showed an increased distance between the femoral neck and the anterior aspect of the joint capsule as compared with the intact side, indicating varying degrees of hip joint effusion and/or synovitis. Hip joint aspiration in 11 patients revealed increased intracapsular pressure varying between 10 and 112 mmHg and volumes of aspirated joint effusion up to 23 ml. Pain relief and increased joint motion after drainage of the intracapsular effusion was observed in 3 patients whose postoperative mobilization was facilitated.