三种颈椎前路固定方式的体外生物力学比较

In vitro biomechanical comparison of three anterior cervical fixation methods

目的:通过体外生物力学方法比较颈椎前路单节段椎间盘切除植骨融合术的零切迹自稳锚定式椎间融合器(Zero-pofile interbody fusion device,Zero-P)和组装式板-笼内固定系统(Skate-plate fusion device,Skate)与传统钛板固定3种不同颈椎前路固定方式的即刻稳定性。方法:24具雄性新鲜山羊颈椎标本(保留C3-4节段),通过X线片及骨密度检查排除骨质破坏、骨质疏松,剔除椎旁肌肉,保留主要韧带、关节囊及椎间盘,对24具山羊颈椎标本进行前屈-后伸、左右侧弯、左右扭转的体外生物力学测试(轴向载荷20N,运动负荷2.5N·m)并记录活动范围(range of motion,ROM)及中性区(neutral zone,NZ)。随后将24具标本随机分为3组:钛板固定组(n=8)、Zero-P组(n=8)、Skate组(n=8),钛板组为C3/4椎间盘置入椎间融合器,再辅助前方传统钛板固定,Zero-P组为辅助Zero-P固定,Skate组为辅助SAKTE固定,再次进行相同加载条件下的屈伸、侧弯、扭转运动,记录标本ROM及NZ。结果:影像学显示术后各组内固定物位置良好,钛板组固定前在前屈、后伸、侧弯、扭转上的ROM分别为9.22°±1.12°、6.34°±0.54°、15.21°±1.28°、1.55°±0.30°,固定后分别为1.30°±0.30°、1.36°±0.40°、1.39°±0.39°、0.94°±0.18°,较固定前明显减小(P<0.05);Zero-P组固定前的ROM分别为9.33°±1.29°、6.60°±0.37°、15.06°±1.42°、1.64°±0.22°,固定后分别为1.50°±0.10°、1.59°±0.51°、1.75°±0.69°、0.75°±0.25°,较固定前明显减小(P<0.05),较钛板组固定后无明显差异(P>0.05);Skate组固定前的ROM分别为9.43°±1.17°、6.64°±0.43°、15.15°±1.21°、1.69°±0.17°,固定后分别为2.50°±0.20°、6.42°±1.89°、8.26°±1.00°、0.87°±0.21°,较固定前,前屈、侧弯、扭转工况下ROM明显减小(P<0.05),但后伸工况下ROM改变不明显(P>0.05);较钛板组固定后,前屈、后伸、侧弯工况下ROM明显增大(P<0.05),扭转工况下ROM无明显差异(P>0.05)。钛板组固定前,前屈-后伸、左右侧弯、左右扭转的NZ分别为8.38°±1.18°、27.05°±2.96°、0.77°±0.27°,固定后分别为1.12°±0.37°、1.17°±0.54°、0.47°±0.17°,较固定前明显减小(P<0.05),Zero-P组固定前分别为8.14°±0.95°、27.67°±1.73°、0.68°±0.28°,固定后分别为1.41°±0.54°、1.99°±0.71°、0.34°±0.12°,较固定前明显减小(P<0.05),较钛板组固定后无明显差异(P>0.05),Skate组:固定前分别为8.06°±0.73°、27.41°±2.53°、0.64°±0.27°,固定后分别为5.13°±1.48°、7.17°±1.74°、0.47°±0.18°,较固定前均明显减小(P<0.05),较钛板组固定后,前屈-后伸、左右侧弯工况下NZ明显增大(P<0.05),扭转工况下NZ无明显改变(P>0.05)。结论:Zero-P与传统钛板力学性能相似,而Skate力学性能弱于传统钛板。

Objectives:To compare the immediate stabilities of Zero-profile inter-body fusion device(Zero-P)and polyetheretherketone(PEEK)assembled plate-cage fusion device(the Skate)with conventional titanium plate fixation in single-level anterior cervical discectomy and fusion(ACDF)through biomechanical test in fresh cadaver specimens.Methods:24 fresh cervical vertebra specimens were collected from 24 male goats(C3-4),and X-ray and bone mineral density examinations were performed to exclude fracture,deformities and osteoporosis.Muscles were removed and main ligaments,joint capsule,and intervertebral discs were preserved.The vitro biomechanical tests of flexion-extension,lateral bending and torsion were performed on 24 goat cervical spine specimens(normal group)and the loading conditions were an axial load of 20N and a kinematic load of 2.5N·m.The range of motion(ROM)and neutral zone(NZ)were collected.And then,the specimens were randomly divided into 3 groups:Titanium plate group(n=8),C3/4 discectomy and intervertebral fusion and anterior fixation by conventional titanium plate;Zero-P group(n=8),C3/4 intervertebral fusion and fixation with Zero-P device;and Skate group(n=8),C3/4 intervertebral fusion and fixation with Skate.Motion simulations were performed in the three groups again under the same loading conditions as the normal group,and the ROMs and NZs were recorded.Results:Postoperative imaging showed that the positions of the prostheses were normal.The titanium group:the ROMs of before fixation in flexion,extension,lateral bending and torsion were 9.22°±1.12°,6.34°±0.54°,15.21°±1.28°,1.55°±0.30°,the ROMs of after fixation were 1.30°±0.30°,1.36°±0.40°,1.39°±0.39°,0.94°±0.18°,which were significantly reduced compared with before fixation(P<0.05).The Zero-P group:the ROMs of before fixation were 9.33°±1.29°,6.60°±0.37°,15.06°±1.42°,1.64°±0.22°.The ROMs of after fixation were 1.50°±0.10°,1.59°±0.51°,1.75°±0.69°,0.75°±0.25°,which were significantly reduced compared with before fixation(P<0.05),and were with no significant difference compared with after fixation of titanium group.The Skate group:the ROMs of before fixation were 9.43°±1.17°,6.64°±0.43°,15.15°±1.21°,1.69°±0.17°,the ROMs of after fixation were 2.50°±0.20°,6.42°±1.89°,8.26°±1.00°,0.87°±0.21°,which,comparing with before fixation,decreased significantly in flexion,lateral bending and torsion condition(P<0.05),but not significantly different in extension condition(P>0.05);and which increased significantly in flexion,extension and lateral bending(P<0.05)comparing with after fixation of titanium group,but not significantly different in torsion condition(P>0.05).The titanium group:the NZs of before fixation in flexion-extension,lateral bending and torsion were 8.38°±1.18°,27.05°±2.96°,0.77°±0.27°,NZs of after fixation were 1.12°±0.37°,1.17°±0.54°,0.47°±0.17°,which were significantly reduced compared with before fixation(P<0.05).The Zero-P group:the NZs of before fixation were 8.14°±0.95°,27.67°±1.73°,0.68°±0.28°,the NZs of after fixation were 1.41°±0.54°,1.99°±0.71°,0.34°±0.12°,which were significantly reduced compared with before fixation(P<0.05),and were with no significant difference compared with after fixation of titanium group(P>0.05).The Skate group:the NZs of before fixation were 8.06°±0.73°,27.41°±2.53°,0.64°±0.27°,NZs of after fixation were 5.13°±1.48°,7.17°±1.74°,0.47°±0.18°,which were significantly reduced compared with before fixation(P<0.05).Comparing with after fixation of titanium group,which increased significantly in flexion-extension and lateral bending(P<0.05),yet not significantly different in torsion condition(P>0.05).Conclusions:Zero-P has the similar mechanical properties as the traditional titanium plate,while Skate is weaker in mechanical properties than the traditional titanium plate.