3D-Printed Individualized Porous Implants for Large Bone Defects: Novel Therapeutic Approach Involving 'Implant-Bone' Interface Fusion

Background: Bone defect repairs are based on bone graft fusion or replacement. However, current large bone defect treatments are inadequate and lack reliable technology. Therefore, we aimed to investigate a simple technique that uses three-dimensional (3D)-printed individualized porous implants without any bone grafts, osteoinductive agents, or surface biofunctionalization to treat large bone defects and systematically study its long-term therapeutic effects and osseointegration characteristics. Methods: Twenty-six patients with large bone defects caused by a tumor, infection, or trauma received treatment with an individualized porous implant; among these, three typical cases underwent a detailed study. Additionally, the large segmental femur defect sheep model was used to study the osseointegration characteristics. Findings: Immediate and long-term biomechanical stability was achieved in patients, and the animal study revealed that the bone grew into the pores with gradual remodeling, resulting in a long-term mechanically stable bone-implant complex. Interpretation: Advantages of 3D-printed microporous implants for the repair of bone defects included the following: stabilization devices were immediately designed and constructed to achieve early postoperative mobility and osseointegration between the host bone and implants was achieved without bone-grafting. Our osseointegration method, in which a microporous metal was used instead of a bone, subverts the traditional idea of osseointegration. Funding: This work was supported by the Ministry of Science and Technology of the People's Republic of China (no. 2016YFB1101501), Beijing Municipal Science & Technology Commission (Project Z181100001718195), and Beijing AKEC Medical Co., Ltd. Declaration of Interests: The authors declare no competing financial interests. Ethics Approval Statement: Study animals: Approval from the Animal Ethics Committee of Peking University Health Science Center (approval no. LA2014214). The study protocol was approved by Peking University Third Hospital Medical Science Research Ethics Committee (IRB00006761- 2016146). All patients provided informed consent.