Collagen crosslinked N-telopeptides as markers for evaluating particulate osteolysis: A preliminary study

The purpose of this study was to determine whether a marker of bone resorpt ion could be used noninvasively to diagnose and assess treatment of peripro sthetic osteolysis. The crosslinked N-telogeptide marker of osteoclast-medi ated bone resorption potentially has the sensitivity to detect periprosthet ic osteolysis. Second-morning urine specimens were obtained from (a) seven age-matched controls, (b) eight patients who had a hip arthroplasty, hybrid implants at least 1 year after surgery, and no osteolysis, (c) 11 patients who had a hip arthroplasty and osteolysis, and (d) 10 patients who had a h ip arthroplasty and with osteolysis before and after 6 weeks of oral Fosama x (alendronate) treatment. The Fosamax treatment consisted of one 10-mg dos e per day for 6 weeks. Men and young women (less than 40 years old) were ch osen for this study to avoid bone resorption enhanced after menopause as a possible confounder. An enzyme-linked immunosorbent assay technique for qua ntifying crosslinked N-telopeptides of type-I collagen was performed on all specimens. The patients with osteolysis had significantly elevated levels of N-telopeptide compared with the implant control group. In addition, leve ls of N-telopeptide were significantly lowered after Fosamax treatment. The se findings indicate that a systemic bone-resorption marker (N-telopeptide) can be used to evaluate local particulate-induced osteolysis and its treat ment. The study also provides clinical evidence that osteolysis is associat ed with increased osteoclast-mediated bone resorption and that this locally induced bone resorption can be suppressed by certain bisphosphonates (Fosa max). These insights have potential value in the understanding and clinical management of aseptic loosening.