Magnetic resonance imaging of the femoral head after acute intracapsular fracture of the femoral neck.

In fifteen patients who had a subcapital fracture of the femoral neck (twelve displaced fractures and three non-displaced fractures), magnetic resonance imaging of the femoral head was done with two-dimensional Fourier transform spin-echo technique within forty-eight hours of injury. The magnetic resonance image did not show avascular necrosis of the femoral head in any of the patients. In eleven patients, there was a decreased signal at the base of the femoral head, immediately adjacent to the fracture. This decreased signal corresponded to a recognized band of necrosis and hemorrhage next to the site of the fracture and was not related to the viability of the femoral head. No other changes were seen on the images. We concluded that this type of magnetic resonance imaging is inadequate to determine the viability of the femoral head within forty-eight hours after a patient sustains an acute intracapsular fracture of the femoral neck.