Successive fracture risk following local bone injury

While it has been previously observed that an injury to the skeleton results in metabolic changes in intact bones distant to the site of the injury, calcium loss at such distant skeletal sites following a local bone injury have never been specifically investigated. In order to determine skeletal effects following local injury, a standardized critical sized defect in the rat femur was treated with either fully demineralized, or partially demineralized, or freeze dried allograft bone and observed after 2 and 4 weeks (n=4/group). In this study we analyzed the calcium loss at different distant skeletal locations including contralateral femurs, radius and ulna, iliac crest, lumbar vertebrae and calvaria following surgical bone restoration. The primary objective of this study was to determine whether an injury resulting in the loss of bone tissue (locally) causes loss of calcium from the skeleton at a site distant from the site of injury. We performed micro-computed tomography in order to analyze the variations in bone quality using both densitometric as well as morphometric parameters across the different groups. The differences between groups were analyzed using two way ANOVA followed by Tukey's post hoc test (p<0.05). Microarchitectural analysis at long bones including femur, radius, and ulna showed significant differences while remaining skeletal sites did not show any significant changes in microarchitectural parameters suggesting that long bone primarily contributes to calcium homeostasis during local fracture healing process. The importance of calcium rich treatment to heal the critical sized bony defect was discussed.