ABSTRACT:The treatment of segmental bone defects is a challenging problem for both human and veterinary medicine. Various biomaterials have successfully been used to treat these defects. Numerous recent in vitro studies have shown the potential of treating bone tissues using poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HAp) nanofibres, which are fabricated using electrospinning. The purpose of this study was to evaluate the possibility of using a bone scaffold of PLGA/HAp nanofibres to repair critical-sized segmental bone defects in a canine model. The experimental bone defects were created in a 15 mm-long region of the radius. The area of the defect in each of 10 Beagle dogs was treated with a transplant of PLGA/HAp nanofibres in gelatin. The control group consisted of five Beagle dogs with similar defect sites that were not treated. Radiological and histological examinations were used to monitor the response of PLGA/HAp nanofibre-treated canine bone. Micro-computed tomography (micro-CT) was used to evaluate bone mass parameters 18 weeks after treatment in the experimental bone defect group. Our radiological and histological results showed that the PLGA/HAp nanofibre is biodegradable in the defect sites and replaces new bone tissue. Micro-CT showed that bone mass parameters were significantly (P < 0.05) increased in the critical-sized segmental bone defects of PLGA/HAp nanofibre-treated animals as compared to those of untreated animals. Based on these results, we conclude that PLGA/HAp nanofibres may be used as a bone scaffold biomaterial in canines.