An experimental study on the feasibility of True Bone Ceramics for the anterior fusion of the spine

点击翻译按钮获取中文摘要

We have performed basic studies on the utilization of sintered bovine bone (True Bone Ceramic : TBC) for the anterior spinal fusion in pig model and revealed the feasibility of TBC as the bone substitute to obtain biological fusion between vertebrae. Although, the physical strength of the TBC is inferior to the biological bone, therefore it was deemed necessity to test the usefulness of the TBC under the condition of sustained compressive stress. For this purpose, 6 monkeys, which sustain sitting poison and bipedal standing, were used for present study. Implanted TBC was consisted with the monocortex on one side and cancellous structure, which is called monocortical-cancellous TBC.Under general anesthesia with extraperitoneal approach, the 5^<th> lumbar vertebra was excised and the block of the monocortical-cancellous TBC was implanted between L4 and L6. For the purpose of reinforcement a screw was inserted to the vertebral bodies of L4 and L6 and single rod was used to connect these two screws. X ray examination was performed at every 3 months and the alignment of the vertebrae and implanted TBC, clear zone at the recipient site and bone formation were carefully observed. No sign of pseudo-arthrosis and compressive deformity of the TBC were found. Extracted spines of L4 and L6 at 10 month after implantation showed 110Mpa in axial strength, 11.8 Nm/deg in torsional strength and 160Nm in compressive strength, which were regarded as sufficient strength. Histological study with Villanueva-Goldner Trichrome staining revealed new bone matrix was growing into the pores of deep layer of the implant and contacts with TBC without any intervening fibrous tissue. At 10 months after implantation, the amount of osteoid cell was small and majority of the space was occupied by newly formed bone. It appears, therefore, from these findings that the monocortical-cancellous TBC can be used for the anterior spinal fusion supplementing with a simple spinal instrumentation.