POSTTRAUMATIC OSTEONECROSIS IN A SWINE MODEL - CORRELATION OF BLOOD-CELL FLUX, MRI AND HISTOLOGY

We used a miniature swine femoral neck fracture model to demonstrate t he effects of the fracture on blood flow, histologic appearance, MRI s ignal and the development of posttraumatic osteonecrosis. The fracture was created and internally fixed in the right hip of 11 swine, with t he left hip serving as the control, Femoral head blood flow via Laser Doppler Flowmetry and MRI data was examined for the experimental hip p reoperatively, postoperatively and at 1, 2, 4 and 8 weeks postfracture , At 8 weeks, the animals were killed and the femoral heads were evalu ated, Femoral head blood flow decreased immediately postfracture and c ontinued to diminish with time, MRI signal intensities in the femoral head at 4 and 8 weeks were significantly less when the fixation failed than when it was intact. Histologic grades (0-14 points) and bone den sities were 7.6 and 49%, respectively, on the experimental side, compa red to 1.6 and 56% on the control side, Histologic grading, bone densi ty values and blood flow data had no relation to changes in MRI signal intensity.