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

本实验对烧结型牛骨(True bone Cerium：TBC)在猪脊柱前路融合中的应用进行了基础研究，揭示了TBC作为骨替代物实现椎间生物融合的可行性。尽管TBC的物理强度不如生物骨，因此有必要测试TBC在持续压应力条件下的有效性。为此，本研究使用了6只处于坐毒和双足站立状态的猴子。植入的TBC由一侧的单皮质和松质结构组成，称为单皮质松质TBC。在腹膜外全麻下，切除第5腰椎，将单皮质松质TBC块植入L4~L6之间。在L4、L6椎体内置入一枚螺钉，用单棒将两枚螺钉连接起来。每3个月做一次X线检查，仔细观察椎体与植入的TBC对齐情况、受区清晰带及骨形成情况。未发现假关节和TBC压缩畸形的征象。植入后10个月取出的L4、L6脊柱轴向强度为110 Mpa，扭转强度为11.8 Nm/deg，压缩强度为160 Nm，为足够强度。Villanueva-Goldner三色染色组织学检查显示，新生骨基质已长入种植体深层的孔隙中，并与TBC接触，没有任何纤维组织介入。植入后10个月，类骨样细胞数量较少，大部分空间被新生骨占据。因此，从这些发现看来，单皮质-松质骨TBC可以用于脊柱前路融合，并辅以简单的脊柱内固定。

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.