[Evaluation of bone metabolism in patients after total hip replacement based on bone turnover markers]

Serum bone markers: N-mid osteocalcin (OCN-Mid) and Cross-Laps were evaluated in 51 patients (15 men and 36 women), age 50-81y. (mean 69) with OA undergoing elective cemented THR. Samples were collected at the day before operation and 3 days, 1, 2, 6 weeks, 3, 6, 12 months after the operation and markers measured by direct chemoluminescency using Modular E-170. Lowest values of both markers were noted at the 3-rd day after operation. Cross-Laps levels rose rapidly reaching highest levels 2 weeks after operation and still were significantly (alpha = 0,05) elevated after 6 weeks. The highest but not statistically significant levels of OCN-Mid were noted after 6 months. After 12 months both markers returned to preoperative values. OCN-Mid/Cross-Laps ratio were lowest after 2 weeks (maximal resorption), then rose over the preoperative value after 3 months, being still significantly elevated after 12 months, indicating that bone formation still occurred. No significant differences were found according to sex, radiolucencies around the endoprosthesis (14 patients) and periarticular ossification (9 patients). Serum bone markers can show the process of bone healing around endoprosthesis, but because of different basic levels of bone metabolism, evaluation of this process can be achieved only with comparison to preoperative values.