Effects of inhibition of bone resorption and cyclooxygenase on bone and tendon-to-bone healing: Experimental studies of fracture and tendon-to-bone healing in the rat

Abstract

Treatment of fractures and ligament injuries often involves orthopedic surgery. In ligament reconstructions, firm tendon-to-bone healing is essential for stability. In fracture treatment, nonunion will significantly impair the outcome. Inhibitors of cyclooxygenase (COX) are effective against pain in orthopedic trauma but might impair bone healing. The aims of the thesis were to characterize tendon-bone healing and assess the effect of bone resorption inhibition by the bisphosphonate zoledronic acid (ZA). We also aimed to investigate the effect of short-time COX-inhibition by parecoxib on fracture healing. The studies conducted were all experimental animal studies in rats. The studies confirmed that tendon-to-bone tunnel healing is a slow process. A native layered tendon-bone interface did not recreate. Still, crossing collagen fibers were associated with an increase of biomechanical strength and bone mineral between 4 and 12 weeks of healing. The main effect of ZA was a reduction of tendon graft pull-out strength by 19% at early time points of healing. We found no negative impact of immediate or delayed three-days treatment with parecoxib on shaft fracture healing in rats.