In Vivo Study of a Self-Stabilizing Artificial Vertebral Body Fabricated by Electron Beam Melting

STUDY DESIGN: In vivo assessment of a novel artificial vertebral body fabricated by electron beam melting (EBM) for cervical vertebral body replacement in a sheep model. OBJECTIVE: To investigate the feasibility of a novel artificial vertebral body: a "self-stabilizing artificial vertebral body" (SSAVB) fabricated by EBM in a sheep model. SUMMARY OF BACKGROUND DATA: Artificial vertebral body is widely used for vertebral body replacement and spinal fusion, but research on an artificial vertebral body fabricated by EBM has not been reported. METHODS: An SSAVB made of porous Ti6Al4V was implanted into a sheep cervical spine to replace the C4 vertebral body for 6 and 12 weeks. Bone ingrowth and implant stability were radiologically evaluated, and histological and biomechanical tests were performed. RESULTS: No screw loosening, implant dislocation, or bone fractures occurred during the experimental period. A significant difference (P = 0.001) in bone ingrowth between the 6- and 12-week groups was noted. Comparison of the range of motion of C3-C5 segments between the in vivo group and the control groups (intact C2-C6 segment and fresh sheep cervical spines from C2 to C6 segments that underwent C4 subtotal corpectomy with the posterior vertebral wall retention by SSAVB implantation) suggests that the implant can stably replace this area of the cervical spine. CONCLUSION: The open porous structure of Ti6Al4V fabricated by EBM facilitated bone ingrowth and the SSAVB can maintain cervical spine stability of the sheep. A porous metal implant can be used for load-bearing applications in a sheep model. It is hoped that these results will stimulate further study in human. LEVEL OF EVIDENCE: 4.