HYPERPARATHYRODISM IN PROXIMAL FEMUR FRACTURES BIOLOGICAL AND HISTOMORPHOMETRIC STUDY IN 21 PATIENTS OVER 75 YEARS OLD

Proximal femur fractures in elderly people are more and more frequent. Falls and senile bone disorders are the risk factors of this fracture. In order to understand the mechanisms of these bone disorders, we studied 21 consecutive patients with this fracture using bone histomorphometry. Measurements of serum intact parathormone (PTH), 25-(OH)-vitamin D, 1,25-(OH) 2-vitamin D and osteocalcin have been performed in these 21 patients, included in a larger series. We excluded patients with renal failure (serum creatinine greater than 140-mu-mols/l), cancer, or previous metabolic bone disease. There were 19 female and 2 male patients, ranging from 75 to 96 years, (mean 84.9). We found a low frequency of cortical (2/21) and trabecular (3/21) osteoporosis. There was no case of clearcut osteomalacia. Following histomorphometric bone study, two patients showed a typical pattern of hyperparathyroidism, and in a third one, this condition seemed very likely. In these three patients who were among the oldest, and who had high levels of serum PTH, chronic renal failure and primary hyperparathyroidism could be excluded. High bone remodeling was frequent in our patients, as reflected by the enhancement of eroded surfaces (13 cases) and of osteoid thickness (7 cases). Intact PTH level was elevated in our series compared to normal values in adults (in accordance to the PTH elevation in the case control study in a larger series). These findings suggest a major role of a secondary hyperparathyroidism in senile bone disorders favoring proximal femur fractures. This hyperparathyroidism is probably secondary to mild calcium and vitamin D deficiency. It may lead to architectural bone changes favoring this fracture. These conclusions suggest that prevention by calcium, vitamin D derivatives, or both, may be useful.