Improved osseointegration with rhBMP-2 intraoperatively loaded in a specifically designed 3D-printed porous Ti6Al4V vertebral implant

Abstract

Three-dimensional (3D)-printed porous Ti6Al4V implants are commonly used for reconstructing bone defects in the treatment of orthopaedic diseases owing to their excellent osteoconduction. However, to achieve improved therapeutic outcomes, the osteoinduction of these implants requires further improvement. The aim of this study was to investigate the combined use of recombinant human BMP-2 (rhBMP-2) with a 3D-printed artificial vertebral implant (3D-AVI) to improve the osteoinduction. Eight male Small Tail Han sheep underwent cervical corpectomy, and 3D-AVIs with or without loaded rhBMP-2 in cavities designed at the center were implanted to treat the cervical defect. Radiographic, micro-computed tomography, fluorescence labelling, and histological examination revealed that the osseointegration efficiency of the rhBMP-2 group was significantly higher than that of the blank control group. The biomechanical test results suggested that rhBMP-2 reduced the range of motion of the cervical spine and provided a more stable implant. Fluorescence observations revealed that the bone tissue grew from the periphery to the center of the 3D-AVIs, first growing into the pore space and then interlocking with the Ti6Al4V implant surface. Therefore, we successfully improved osseointegration of the 3D-AVI by loading rhBMP-2 into the cavity designed at the center of the Ti6Al4V implant, realizing earlier and more stable fixation of implants postoperatively in a simple manner. These benefits of rhBMP-2 are expected to expand the application range and reliability of 3D-printed porous Ti6Al4V implants and improve their therapeutic efficacy.