Biochemical bone markers are useful to monitor fracture repair.

UNLABELLED: Biochemical bone markers reflect bone metabolism but little is known regarding their usefulness during fracture repair. Reduced bone mineral density may influence fracture healing. We hypothesized that low bone mineral density results in decreased levels of bone markers during the acute phase of fracture healing, especially in women who are postmenopausal. We also addressed the question of different fracture types and locations resulting in different levels of bone markers. Urinary levels of N-terminal cross-linked telopeptide, deoxypyridinoline, and pyridinoline were measured preoperatively and postoperatively in patients with hip fractures, distal forearm fractures, and in 25 control subjects. Bone mineral density was determined using quantitative computed tomography of the spine. Patients with low bone mineral density, especially women who were postmenopausal, had greater concentrations of N-terminal cross-linked telopeptide when compared with patients with normal bone mineral density or men. Patients with pertrochanteric fractures had greater concentrations than patients with femoral neck fractures, as did patients with hip fractures compared with patients with fractures of the distal forearm. These results suggest that levels of bone markers increase during fracture healing despite low bone mineral density and that different fracture types and locations result in different levels of bone markers. LEVEL OF EVIDENCE: Prognostic study, Level I (high quality prospective study-all patients were enrolled at the same time with > or = 80% of followup of enrolled patients). See the Guidelines for Authors for a complete description of levels of evidence.

Urinary excretion of pyridinium crosslinks of collagen in patients with osteoporosis and the effects of bone fracture.

Values for the urinary excretion of pyridinium crosslinks of collagen, pyridinoline and deoxypyridinoline, in a group of 30 elderly women with femoral fractures associated with osteoporosis and a group of 20 women without recent fracture but with overt or suspected osteoporosis were compared with 27 control subjects matched for age. Relative to the control group, the excretion of the crosslinks was significantly higher in the group with fractures and the group with osteoporosis. Fractures contributed markedly to the excretion of pyridinium crosslinks as the patients with fractures showed significantly higher excretion of pyridinoline and deoxypyridinoline than the group without recent fractures. This was confirmed by the fact that excretion of pyridinium crosslinks in patients with accidental bone fractures was significantly higher than for healthy control subjects matched for age and sex. The crosslinks appear to provide valid indices of bone resorption, but the effects of bone fracture must be considered in the clinical application of this technique.