Lack of metabolic bone disease in patients with fracture of the femoral neck.

To examine the widely held belief that osteoporosis and osteomalacia are pathogenetic factors in femoral neck fracture, we compared such patients with vertebral fracture patients and controls. Cortical bone was measured in hand X-rays and cancellous bone in iliac crest biopsies, which were also used to assess osteoid, tetracycline and resorbing surface. The vertebral fracture patients were found to have a reduction of 53% and 41% in cancellous and cortical bone respectively compared to the controls, while in the much older femoral fracture patients the reductions were 19% and 16%. Three femoral fracture patients had mild osteomalacia from identifiable causes; a further one had fluorosis of bone and one had metastatic carcinoma; with the exception of these the osteoid covered surface of bone was less than in vertebral fracture patients and controls. We conclude that pathologic osteoporosis and osteomalacia are not major factors in the pathogenesis of femoral neck fractures, though the normal age related reduction in bone mass may contribute. There may be another age related factor weakening the femoral neck. It was also noted that when assessed by a sensitive histochemical technique for osteoclast identification, bone resorption was not increased in either of the fracture groups.