3D打印多孔钛合金与聚醚醚酮椎间融合器对羊颈椎融合效果的对比研究

3D-printed porous titanium cage versus polyetheretherketone cage in sheep vertebral fusion

目的探讨3D打印多孔钛合金融合器对动物颈椎的融合效果，并与聚醚醚酮（PEEK）椎间融合器进行对比观察。方法取18只普通级雌性小尾寒羊，均行颈前路椎间盘切除术后，按其C3-4与C4-5椎间隙置入的椎间融合器不同分为2组（n=9）：3D打印多孔钛合金椎间融合器；PEEK椎间融合器加自体植骨（对照组）。术后3、6个月，两组分别处死3只实验动物行X线、Micro-CT检查及组织学检测，计算材料中骨长入体积占材料孔隙体积的百分比（BVF）、置入物内的矿化骨百分比（MBF）和材料．骨结合百分比（BA）；术后6个月，两组分别处死剩余3只实验动物用于生物力学检测，测量最大力矩时下位椎体相对于上位椎体的角度位移范围（ROM）。结果X线及Micro-CT结果显示两组融合器在术后6个月均达到完全融合。3D打印多孔钛合金孔隙中骨长入体积随时间增长：术后3个月实验组与对照组BVF分别为27．1％±3．7％、37．6％±8．2％，差异有统计学意义（P〈0．05）；但术后6个月分别为39．7％±3．4％、40．0％±4．1％，差异无统计学意义（P〉0．05）。组织学观察可见新生骨逐渐长入3D多孔钛合金的孔隙之中，形成紧密的骨-材料结合界面：术后3个月实验组与对照组MBF分别为22．2％±3．2％、34．3％％±5．0％，差异有统计学意义（P〈0．05）；但术后6个月分别为38．4％±1．7％、36．3％±4．0％，差异无统计学意义（P〉0．05）。术后3、6个月实验组BA分别为10．6％±2．1％、59．5％±8．6％，与对照组的4．6％±2．0％、5．8％±3．6％比较差异均有统计学意义（P〈0．05）。术后6个月，生物力学测试结果显示实验组的颈椎融合节段的ROM显著小于对照组，差异有统计学意义（P〈0．05）。结论3D打印技术制备的多孔钛合金椎间融合器在羊颈椎融合模型中可达到良好的融合效果，与PEEK融合器相比具有更好的骨-材料结合界面，可使融合节段更加稳定，具有良好的临床应用前景。

Objective To evaluate the roles of 3D-printed porous Ti-6Al-4V cages and polyetheretherketone （PEEK） cages in vertebral fusion in a preclinical sheep model. Methods Cervical anterior diskectomy was conducted in 18 mature female Small Tail Han sheep which were randomized into 2 even groups. 3D-printed porous Ti-6Al-4V cages were implanted into 2 levels of cervical disc （C3-4 and C4-5） in the experimental group （ n = 9） and PEEK cages （plus bone autograft） in the control group （ n = 9）. Each time at 3 months and 6 months after surgery, 3 animals in each group were sacrificed for X-Ray, Micro-CT and histological examinations to measure bone volume fraction （BVF）, mineralized bone fraction （MBF） and bone apposition （BA） in the cage. At 6 months, the remaining 3 animals in each group were sacrificed for biomechanical analyses to measure range of motion （ROM） of the lower vertebral body relative to the upper vertebral body under the maximum moment. Results X-Ray and Micro-CT evaluations showed that all cages obtained complete fusion at 6 months. A rapid ingrowth of bone tissue into the 3D-printed porous Ti-6Al-4V cages was found. At 3 months, BVF in the experimental group （27. 1% ± 3.7% ） was significantly lower than in the control group （37.6% ± 8.2% ） （ P 〈 0.05）, but such a difference disappeared at 6 months （39.7% ± 3.4% versus 40. 0% ±4. 1% ） （ P 〉 0. 05）. Histological evaluation showed that the bone tissue in the pores bound closely with the Ti alloy to form intimate bone-material connection. At 3 months, MBF in the experimental group （22. 2% ± 3.2% ） was significantly lower than in the control group （34. 3% ± 5.0% ） （ P 〈 0. 05）, but such a difference disappeared at 6 months （38.4% ± 1.7% versus 36. 3% ±4.0%） （P〉 0.05）. At 3 and 6 months, BA was respectively 10.6% ±2. 1% and 59.5% ±8.6% in the experimental group, showing significant differences from those in the control group （4. 6% ± 2.0% and 5.8% ± 3.6% respectively） （ P 〈 0.05）. At 6 months, ROM of the fused segment in the experimental group was significantly smaller than that in the control group （ P 〈 0. 05 ） . Conclusions In the sheep model of cervical anterior fusion, porous Ti-6Al-4V cages fabricated by 3D printing can achieve rapid bone ingrowth. In addition, since they demonstrate better bone-material integration and mechanical stability than PEEK cages, they have a great potential for clinical application.