LOSS OF BONE IN THE PROXIMAL PART OF THE FEMUR FOLLOWING UNSTABLE FRACTURES OF THE LEG

We evaluated the subsequent loss of bone from the proximal part of the ipsilateral and contralateral femora and from the lumbar spine of sev en men and nine women who had a fracture of the tibia. The average age was sixty years. All of the fractures were unstable, and the involved leg bore no weight for an average of eight weeks. The bone mineral de nsity was measured with dual-energy x-ray absorptiometry of the lumbar spine and of the femoral neck and the trochanteric region of both hip s immediately after the fracture, after the period of immobilization, and at approximately three, six, and twelve months after the fracture. During the period of immobilization, the bone mineral density of the trochanteric region decreased an average of 9 +/- 7 per cent on the si de of the fracture, compared with the value immediately after the frac ture, but there was no change on the contralateral side (p < 0.01). At twelve months, the average decrease in the trochanteric area was 15 /- 10 per cent on the side of the fracture, compared with the value im mediately after the fracture, but again there had been no change on th e uninjured side (p < 0.01). The bone mineral density of the femoral n eck on the side of the fracture had decreased 6 +/- 6 per cent at twel ve months, compared ,vith a decrease of 2 +/- 4 per cent on the uninju red side (p < 0.05). The bone mineral density of the lumbar spine decr eased only during the period of unloading of the fractured leg (If 2 p er cent, p = 0.01). The hydroxy-proline-creatinine ratio, which was de termined from a two-hour urine collection while the patient was fastin g, increased significantly during the period of unloading of the fract ured leg. Thus, treatment of a fractured leg with immobilization and n on-weight-bearing led to significant loss of bone from the ipsilateral hip. Signs of recovery in the trochanteric region were not visible on e year after the fracture.