Boden S D, Martin G J, Horton W C, Truss T L, Sandhu H S
Department of Orthopedics, Emory University School of Medicine, The Yerkes Regional Primate Center, Atlanta, Georgia, USA.
J Spinal Disord. 1998 Apr;11(2):95-101.
Anterior lumbar interbody arthrodesis is commonly performed for conditions involving infection, deformity, and instability. The purpose of this investigation was to determine the effective dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) as a bone graft substitute inside a titanium threaded interbody fusion cage using a nonhuman primate model of laparoscopic anterior lumbar interbody arthrodesis. Eight adult rhesus monkeys underwent laparoscopic exposure of the lumbosacral spine followed by insertion of a hollow titanium threaded cylindrical cage (Sofamor-Danek, Memphis, TN, U.S.A.). Before insertion, the chamber of the cage was filled with a collagen sponge delivery vehicle soaked with either 0 mg/ml (sham, buffer only), 0.75 mg/ml (low dose), or 1.5 mg/ml (high dose) of rhBMP-2 (Genetics Institute, Cambridge, MA, U.S.A.). Fusions were evaluated in a blinded fashion with plain radiographs and computed tomography (CT) scans 12 and 24 weeks after surgery, and by manual palpation and histology after euthanasia 24 weeks after surgery. All five monkeys treated with a cage filled with rhBMP-2 obtained a solid fusion as assessed by manual palpation. The two monkeys that received no growth factor did not achieve solid fusions. Plain radiographs were of limited value, with fusions best assessed on sagittally reconstructed CT scans. Scans from the two animals treated without growth factor showed ingrowth of bone only into the outer edges of the cage, but not through the center. Scans from the rhBMP-2-treated animals demonstrated arthrodesis with continuous bone growth through the cage. Histologic analysis demonstrated normal mature trabecular bone surrounding and growing through the cages, which correlated with the CT scan findings. We conclude that rhBMP-2 delivered in a threaded titanium interbody cage can serve as a bone graft substitute in a nonhuman primate model. Sagittal reconstructed CT may be a better method to assess for fusion with this device.
前路腰椎椎间融合术常用于治疗感染、畸形和不稳定等病症。本研究的目的是使用腹腔镜前路腰椎椎间融合术的非人灵长类动物模型，确定重组人骨形态发生蛋白-2（rhBMP-2）作为钛螺纹椎间融合器内骨移植替代物的有效剂量。八只成年恒河猴接受了腹腔镜下腰骶部脊柱暴露，随后植入一个中空的钛螺纹圆柱形融合器（美国田纳西州孟菲斯市索法莫尔-丹内克公司生产）。在植入前，融合器腔室填充有浸泡了0毫克/毫升（假手术组，仅含缓冲液）、0.75毫克/毫升（低剂量组）或1.5毫克/毫升（高剂量组）rhBMP-2（美国马萨诸塞州剑桥市基因研究所生产）的胶原海绵递送载体。术后12周和24周通过盲法利用X线平片和计算机断层扫描（CT）评估融合情况，术后24周安乐死后通过手动触诊和组织学检查进行评估。所有五只接受填充rhBMP-2融合器治疗的猴子经手动触诊评估均获得了牢固融合。两只未接受生长因子治疗的猴子未实现牢固融合。X线平片价值有限，融合情况最好通过矢状面重建CT扫描进行评估。未接受生长因子治疗的两只动物的扫描显示，骨仅长入融合器的外缘，而未穿过中心。接受rhBMP-2治疗动物的扫描显示椎间融合，骨持续生长穿过融合器。组织学分析显示，融合器周围和内部有正常成熟的小梁骨生长，这与CT扫描结果相符。我们得出结论，在螺纹钛椎间融合器中递送的rhBMP-2可作为非人灵长类动物模型中的骨移植替代物。矢状面重建CT可能是评估该装置融合情况的更好方法。
