Fracture healing results in increased markers of bone turnover and callus formation. The exact patterns of these changes after different type and locations of fractures as well as weight bearing are unknown.

Bone markers and the callus index were measured prospectively for 6 month following osteosynthesis of different fractures of the lower limb. Serum and urin samples were collected at day 0, 1, 3, 7 and after 2, 6, 12 and 24 weeks. X-rays were taken direct postoperatively and after 6 and 24 weeks. Labarotory parameters for bone formation were: bone-specific alkaline phosphatase (BnAP), Osteocalcin (OC), procollagen type I N- and type III C-terminal propeptide (PINP, PIIICP); markers for bone resorption were: free and peptid-bound forms of urinary pyridinium crosslinks (Dpd, Pyr,), N – terminal propeptides of type I collagen (NTx). All fractures healed within 6 month without complications.

Results: We present preliminary data obtained from 12 adults (10 male, 2 female, mean age 45±15 years). a great variability of bone formation and resorption markers was observed during the first two weeks, probably due to the type trauma and amount of soft tissue injury. Accelerated bone resorption, and a decrease of bone formation was observed during the first week. Thereafter, an increase in OC and BnAP was noted despite persistently elevated bone resorption markers. With increasing weigth bearing, a decrease of bone resorption markers with unchanged or slightly increasing levels of bone formation markers occured.

Conclusions: No fracture specific trends for changes in bone remodelling markers were observed. Accelerated bone resorption is followed by increased bone formation; the longer and steeper the increase on bone resorption, the later and more pronounced the increase in bone formation. For further evaluation of the relationship between changes in bone remodeling markers and fracture healing, more patients will be included into the ongoing study.