Regenerative repair of large bone defects currently remains a challenging issue during surgery, owing to the limited regenerative ability of the bone. To address this issue, we attempted a precise repair of a bone defect using computer-aided procedures. Using pelvic computed tomography (CT) images of beagle dogs, virtual tumors were created in the pelvis using computer-aided design (CAD), and a bone resection following the margins of the bone tumor was performed on the CAD image. Hydroxyapatite

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... (HA) implants to fill the bone defects and implants for shape evaluation of bone resection sites were designed and produced by computer-aided manufacturing and threedimensional printing. Subsequently, using a computer navigation system, iliac bone defects were created in beagle dogs as preoperatively planned on CAD, filled with HA implants shaped to fit the bone defect sites, and coated with a recombinant human bone morphogenetic protein (rhBMP)-2-containing dough bone-forming material. Postoperative CT revealed that the new bone was formed around the implant over time. Anatomical healthy bone repair was confirmed to be completed 12 weeks after the surgery. These results demonstrate potential novel technology for efficacious and accurate repair of large bone defects without bone grafting.