Objectives

Recent studies have shown that modulating inflammation-related lipid signalling after a bone fracture can accelerate healing in animal models. Specifically, decreasing 5-lipoxygenase (5-LO) activity during fracture healing increases cyclooxygenase-2 (COX-2) expression in the fracture callus, accelerates chondrogenesis and decreases healing time. In this study, we test the hypothesis that 5-LO inhibition will increase direct osteogenesis. Methods Bilateral, unicortical femoral defects were used in rats to measure the effects of local 5-LO inhibition on direct osteogenesis. The defect sites were filled with a polycaprolactone (PCL) scaffold containing 5-LO inhibitor (A-79175) at three dose levels, scaffold with drug carrier, or scaffold only. Drug release was assessed in vitro. Osteogenesis was assessed by micro-CT and histology at two endpoints of ten and 30 days