颈椎前路生物活性玻璃涂层钛板系统的研制与生物力学评价

DESIGN AND BIOMECHANICAL EVALUATION OF ANTERIOR CERVICAL BIOGLASS-COATING PLATE SYSTEM

目的 研制颈椎前路生物活性玻璃钛板系统（ACBPS），并对其进行生物力学评价。方法 在钛板内面及累钉表面等离子喷涂0.3mm厚的生物活性玻璃涂层。采用18具颈椎标本随机分为ACBPS，颈前路钛板系统（ACPS），和Orion三组，在颈前路减压，植骨及钛板内固定后，行载荷－位移，扭矩和扭转刚度，极限力学性能测定并记录结果，进行对比；另对ACBPS，ACPS行拔出试验和疲劳试验，且以三维有限元素分析验证。结果 在前屈，后伸时ACBPS组的纵向位移降低幅度明显高于ACPS组或Orion组（P＜0．05），同时其纵向位移值明显低于ACPS组或Orion组（P＜0．05）；ACBPS组的扭转矩和扭转刚度以及极限力学性能与ACPS组或Orion组比较均无统计学差异（P＞0．05）；但其在最大拔出力及相对位移和能量吸收值上增明显高于ACPS组和Orion组（P＜0．05）；其疲劳强度586.86MPa，疲劳载荷达6．55×10^5次；有限元计算得出ACBPS孔洞直径和孔边距离处安全范围。结论 ACBPS角能较好地重建颈椎稳定性且有效防止螺钉及系统整体松动，并能通过涂层的固合来降低螺孔周围应力集中从而延长其使用寿命，可供体内较长时间安放。

Objective To evaluate the biomechanical properties of self- designed anterior cervical bioglass- coating plate system (ACBPS) . Methods A 0.3mm coating thickness of bioglass was sprayed isoionically onto the surface of the screws and the reverse side of the plate. 18 cervical spine specimens(C2 -T1)were divided into three groups. After decompression, bone graft and implant fixiation with ACBPS, ACPS or Orion, the load-displacement, torque, twisting stiffness and ultimate mechanical performance were tested and compared. Furthermore, ACBPS and ACPS were subjected to pull-out test and fatigue test, and the results were further justified with a three dimensional finite element model. Results The results showed that the ranges of displacement decrease of ACBPS group was more significant than those of ACPS or Orion ( P < 0.05 ) in flexion-extension and the longitudinal displacements after fixation were lower ( P < 0.05 ) than those two implant groups as well. But torque,twisting stiffness and ultimate mechanical performance of ACBPS group were similar to those of ACPS or Orion ( P > 0.05 ) group. The maximum pull-out force and its relative displacement and energy absorption of ACBPS were greater than those of ACPS or Orion ( P < 0.05 ) . Its fatigue strength was 586.86MPa and could bear 6.55 · 105 times of loading on average before they appeared fissures externally to the screw holes. Althougth the stress concentration was located circum-ferentially of the holes of ACBPS, the diameter of holes and the distance of edges were still in the margin of safety. Conclusion ACBPS can not only provide sufficient biomechanical stability and prevent the loosening of screws or the system, but also reduce the stress concentration on the holes of the plate by its bioglass coating which prolongs its service life and is safe for long - time internal fixation.