THE POSTOPERATIVE COURSE OF THE SERUM LEVELS OF OSTEOPROTEGERIN, RECEPTOR ACTIVATOR FOR NUCLEAR FACTOR-{KAPPA} B LIGAND (RANKL), OSTEOCALCIN AND BONE-SPECIFIC ALKALINE PHOSPHATASE (B-ALP) FOLLOWING TOTAL HIP AND KNEE ARTHROPLASTY: A PROSPECTIVE OBSERVATIONAL, ONE-YEAR FOLLOW-UP STUDY.

Background: The clinical significance of bone turnover markers is well recognized, at least in several diseases affecting the bone metabolism. However, their clinical significance (if any) remains still unknown in patients undergoing Total Joint Arthroplasty (TJA). Changes in the levels of some markers have been reported in the early postoperative period after Total Hip Arthroplasty; however their exact postoperative course has not been clearly documented yet. In order to assess the clinical value of biochemical markers when trying to determine the fixation of orthopaedic implants, it is necessary to clarify their normal postoperative course. The aim of this study was to extend the evaluation of the course of bone turnover markers over a longer period (12 postoperative months) following a TJA, and to assess the postoperative course for two of them (RANKL and Osteoprotegerin) for the first time. Methods: The serum levels of RANKL, Osteocalcin, Osteoprotegerin and bALP were determined one day preoperatively and several times during the first postoperative year in patients suffering from idiopathic osteoarthritis that underwent total knee (n=23) and hip arthroplasties (n=24). Results: There were statistically significant changes in the serum levels of all markers over time (p Conclusions: The levels of all bone markers did not uniformly ‘return’ to their preoperative values one year postoperatively. A one-year period is not enough, when assessing an orthopaedic implant’s fixation with the use of bone turnover markers.