Magnetic resonance imaging of the hip after displaced femoral neck fractures.

This study was designed to determine the sensitivity of magnetic resonance imaging (MRI) in the detection of ischemia or avascular necrosis after displaced intracapsular hip fractures. Magnetic resonance imaging was performed on 20 patients who had hemiarthroplasties performed for Garden IV intracapsular fractures. Sixteen patients had in vivo coronal T1-weighted spin-echo imaging from the day of injury to 60 days after fracture. After hemiarthroplasty, all 20 resected femoral heads had in vitro T1 imaging. A coronal slab was then cut from the center of the femoral head and studied histologically. The in vivo, in vitro, and histologic slides correlated well. None of the MRI images depicted areas of ischemia or avascular necrosis in patterns observed in nontraumatic necrosis. Avascular bone can be indistinguishable from normal bone in both MRI and histologic sections for a considerable amount of time after vascular insult. Magnetic resonance imaging is not a prognosticator for posttraumatic osteonecrosis in the first two weeks after fracture.

Diagnosis of occult fractures about the hip. Magnetic resonance imaging compared with bone-scanning.

Sixty-two consecutively seen patients in whom a fracture about the hip was clinically suspected, but in whom the radiographic findings were negative, were examined with both magnetic resonance imaging and bone-scanning. The magnetic resonance-imaging studies, consisting of T1-weighted coronal sections, were done within twenty-four hours after admission to the hospital, and the bone scans, within seventy-two hours after admission. There were twenty-three men and thirty-nine women. Thirty-six patients who had evidence of a fracture on the magnetic resonance-imaging study also had a positive bone scan initially. Twenty-three patients who had a negative finding on the magnetic resonance-imaging study had a corresponding negative bone scan. Two additional patients had evidence of avascular necrosis of the femoral head on both the magnetic resonance image and the bone scan, and they were managed non-operatively. One patient had a positive magnetic resonance image and a negative bone scan twenty-four hours after admission. A repeat bone scan, which was made six days later, was positive for a fracture of the femoral neck and the patient was managed with internal fixation. Magnetic resonance imaging was as accurate as bone-scanning in the assessment of occult fractures of the hip. The magnetic resonance imaging took less than fifteen minutes to perform, and it was tolerated well by the patient. Magnetic resonance imaging provides an early diagnosis of occult fractures about the hip and may decrease the length of the stay in the hospital by expediting definitive treatment.