寰枢椎前路复位钢板系统的研制及其生物力学

目的研制一种经口咽前路寰枢椎复位钢板内固定系统,评价其生物力学性能。方法研制各种型号经口咽前路寰枢椎复位钢板和复位器等配套器械。选12具新鲜成年颈椎标本,分别进行三维运动范围实验和螺钉拔出力实验。与其它内固定方法作比较分析。结果生物力学测试表明,三维运动范围,该钢板固定和Magerl Brooks固定在各个方向上均无显著差异(P>0.05)。其抗屈伸、侧屈和旋转均强于其它三种内固定方法。寰椎螺钉的最大拔出力显著高于枢椎和C3椎体固定螺钉,枢椎螺钉与C2螺钉等效。结论寰枢椎前路复位钢板系统设计新颖,具有良好的生物力学性能。能满足临床内固定需要。     

新型上颈椎前路钩状钛板治疗寰枢椎不稳的生物力学测试

[目的]测试研究新型上颈椎前路钩状钛板治疗寰枢椎不稳的生物力学稳定性.[方法]采用上颈椎新鲜尸体标本6例依次参加5组试验:正常状态组、寰枢椎不稳组、新型上颈椎钩状钛板固定组、前路经寰枢关节螺钉固定组及后路Brooks钢丝固定组,利用SPSS 13.0软件包进行重复测量的方差分析,组间两两比较采用SNK检验法,差异标准置于0.05.[结果]前屈稳定性上,新型上颈椎钩状钛板组和Brooks组差异无显著性(P=0.525),但两者不如前路经寰枢关节螺钉组(P<0.05).后伸稳定性上,新型上颈椎钩状钛板组和前路经寰枢关节螺钉组差异无显著性(P=0.372),且两者稳定性明显强于Brooks组(P<0.05).侧屈上,前路经寰枢关节螺钉组与新型上颈椎钩状钛板组差异无显著性(P=0.216),且两者稳定性明显强于Brooks组.旋转稳定性上,前路经寰枢关节螺钉组优于新型上颈椎钩状钛板组,而后者又较Brooks组稳定性强(P<0.05).[结论]新型上颈椎前路钩状钛板具有一定的生物力学强度,其对于寰枢椎的稳定性弱于前路经寰枢关节螺钉,但明显强于Brooks,能够为寰枢椎不稳的病例提供可靠的固定强度.     

后路寰椎侧块螺钉联合枢椎椎板钩内固定的生物力学稳定性

目的研究后路寰椎侧块螺钉联合枢椎椎板钩内固定的生物力学稳定性。方法取6例新鲜尸体颈椎标本,每具标本分别依次进行完整(正常组)、寰枢椎不稳(失稳组)、寰枢侧块螺钉联合枢椎椎弓根螺钉钉棒固定(Harms组)、寰椎侧块螺钉联合枢椎椎板钩固定(钉钩组)状态的生物力学测试,每组6个标本,将各标本装载在脊柱三维运动机上,分别施予1.5 N·m力矩,记录标本在前屈后伸、左右侧曲、左右旋转3个方向上的活动度(ROM),比较各组ROM。结果相对于正常组标本,失稳组标本在上述3个方向上的ROM显著增大;相较于正常和失稳组标本,Harms组和钉钩组的标本在上述3个方向上ROM显著减小;钉钩组与Harms组间在上述3个方向的ROM差异无统计学意义(P0.05)。结论后路寰椎侧块螺钉联合枢椎椎板钩内固定在生物力学稳定性上与Harms固定相似,可以起到良好的固定效果。     

经口咽前路寰枢椎复位钢板的生物力学评价

目的　对经口咽前路寰枢椎复位钢板 (TransoralpharyngealAtlantoaxialReductionPlate ,TARP)。进行生物力学评价。 方法　 6例寰枢椎新鲜标本 ,在脊柱三维运动试验机上将四种常用的寰枢前后路融合术与我们自行设计的经口咽前路寰枢椎复位钢板进行对比 ,分 7组 :①对照组 (完整标本 ) ;②损伤组 ;③前路寰枢椎复位钢板组 ;④后路Brooks钢丝组 ;⑤Magerl +Brooks组 ;⑥Magerl组 ;⑦前路经枢椎体寰椎侧块螺钉组 (ATS)。分别测量其三维运动范围 (ROM)。 结果　TARP和Magerl+Brooks在各个方向上均无显著性差异 ,ROM值略大于后者 ,除在侧屈时和旋转与Magerl无显著差异外 ,二者抗屈伸、侧屈和旋转均强于其它内固定方法。Magerl除在侧屈和旋转范围与Brooks、前路经枢椎体寰椎侧块螺钉的旋转范围无显著差异外 ,与Brooks和前路经枢椎体寰椎侧块螺钉在其它运动有显著差异 ,ROM值小于Brooks和前路经枢椎体寰椎侧块螺钉。Brooks和前路经枢椎体寰椎侧块螺钉在各向上均无显著差异。结论　TARP与Magerl+Brooks较其它三种临床上常用的前后路寰枢融合手术固定更牢靠 ,TARP具有良好的生物力学性能。联合后路Magerl+Brooks较单用后路Magerl更牢固。前路经枢椎体寰椎侧块螺钉固定与Brooks钢丝效果相当     

经口咽前路寰枢椎蝶形钢板系统的设计及生物力学评估

目的　设计经口咽前路寰枢椎蝶形钢板内固定系统 ,评价其生物力学性能。方法　设计研制各种型号经口咽前路寰枢椎蝶形钢板、自锁螺钉和复位器等配套器械。选 12具新鲜成年颈椎标本 ,分别进行三维运动范围实验和螺钉拔出力实验。与其他内固定方法作比较分析。结果三维运动范围 ,TARP、Brooks、Magerl、前路经枢椎体寰椎侧块螺钉和Magerl Brooks组的屈伸方向的运动范围分别为平均 4.0、6.2、5 .1、6.6和 3 .7度 ;在侧屈方向的活动范围分别为平均 2 .3、3 .6、2 .7、4.2和 1.8度 ;在旋转活动范围分别为平均 7.4、8.9、8.6、10 .7和 6.0度。结果显示该蝶形钢板固定和Magerl Brooks固定在各个方向上差异均无显著性 (P >0 .0 5 )。其抗屈伸、侧屈和旋转均强于其他 3种内固定方法。寰椎、枢椎和第 3颈椎组的螺钉固定的最大拔出力分别为平均491.5 8、3 96.73和 3 85 .5 3N。结果显示寰椎螺钉的最大拔出力显著高于枢椎和C3 椎体固定螺钉 ,枢椎螺钉与C2 螺钉等效。结论　经口咽前路蝶形钢板系统设计新颖、独特 ,具有良好的生物力学性能。为临床应用提供了生物力学依据。     

经口咽前路寰枢椎复位钢板的生物力学评价

目的 对经口咽前路寰枢椎复位钢板(Transoralpharyngeal Atlantoaxial Reduction Plate，TARP)。进行生物力学评价。方法 6例寰枢椎新鲜标本，在脊柱三维运动试验机上将四种常用的寰枢前后路融合术与我们自行设计的经口咽前路寰枢椎复位钢板进行对比，分7组：①对照组(完整标本)；②损伤组；③前路寰枢椎复位钢板组；④后路Brooks钢丝组；⑤Magerl Brooks组；⑥Magerl组；⑦前路经枢椎体寰椎侧块螺钉组(ATS)。分别测量其三维运动范围(ROM)。结果 TARP和Magerl Brooks在各个方向上均无显著性差异，ROM值略大于后者，除在侧屈时和旋转与Magerl无显著差异外，二者抗屈伸、侧屈和旋转均强于其它内固定方法。Magerl除在侧屈和旋转范围与Brooks、前路经枢椎体寰椎侧块螺钉的旋转范围无显著差异外，与Brooks和前路经枢椎体寰椎侧块螺钉在其它运动有显著差异，ROM值小于Brooks和前路经枢椎体寰椎侧块螺钉。Brooks和前路经枢椎体寰椎侧块螺钉在各向上均无显著差异。结论 TARP与Magerl Brooks较其它三种临床上常用的前后路寰枢融合手术固定更牢靠，TARP具有良好的生物力学性能。联合后路Magerl Brooks较单用后路Magerl更牢固。前路经枢椎体寰椎侧块螺钉固定与Brooks钢丝效果相当。     

经寰枢关节间隙螺钉和寰椎椎板钩内固定的力学稳定性

目的评价双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定的力学稳定性。方法将6具新鲜尸体颈椎标本（包括枕骨基底部和C1-C4颈椎节段）置于1．5Nm载荷下，测量C1，2节段的三维运动范围（range of motion，ROM）。标本依Gallie内固定、双侧经寰枢关节间隙螺钉和Gallie内固定、双侧经寰枢关节间隙螺钉内固定、双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定、双侧寰椎侧块螺钉和枢椎椎弓根螺钉内固定的顺序实施固定，每次固定后测量三维运动范围。结果包含经寰枢关节间隙螺钉的内固定组在旋转和侧屈方向上具有最小的ROM，其中双侧经寰枢关节间隙螺钉和寰椎椎板钩内固定组在屈伸运动方向上也具有最小的ROM。寰椎侧块螺钉和枢椎椎弓根螺钉内固定组在旋转方向上ROM大于单纯经寰枢关节间隙螺钉内固定组，但在侧屈和屈伸方向上接近经寰枢关节间隙螺钉，差异无统计学意义；其在侧屈和旋转方向上ROM均小于Gallie内固定组，差异有统计学意义。结论双侧经寰枢关节间隙螺钉和寰椎椎板钩“三点”内固定具有最强的生物力学稳定性。虽然双侧寰椎侧块螺钉和枢椎椎弓根螺钉内固定在生物力学稳定性上不及“三点”内固定，但明显优于Gallie内固定。     

三种后路寰枢椎融合术的离体生物力学研究

目的 通过离体生物力学研究方法,比较3种后路寰枢椎融合技术的力学稳定性.方法 将8具新鲜尸体的颈椎标本(C1～4)置于1.5 Nm载荷下,测量C1、2关节的三维运动范围(ROM).每具标本依双侧经寰枢关节间隙螺钉结合Gallie内固定术、双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定术、双侧寰椎侧块螺钉结合枢椎椎弓根螺钉内固定术的顺序实施固定,每次固定后测量三维运动范围.结果 包含经寰枢关节间隙螺钉的内固定组在旋转和侧屈方向上具有最小的ROM角度,其中新型的双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定组在前屈后伸运动方向上也具有最小ROM角度.寰椎侧块螺钉结合枢椎椎弓根螺钉内固定组在旋转方向上ROM角度显著大于单独经寰枢关节螺钉内固定组,但在侧屈和前屈后伸方向上ROM角度近似于经寰枢关节间隙螺钉,差异无统计学意义.结论 双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定术具有最强的生物力学稳定性;双侧寰椎侧块螺钉结合枢椎椎弓根螺钉内固定术与双侧经寰枢关节间隙螺钉结合寰椎椎板钩内固定技术比较,具有相似的力学稳定性.     

寰枢关节前后路侧块螺钉内固定的生物力学比较

目的：比较寰枢关节前、后路侧块螺钉固定的效果，并测定其双侧、单侧侧块螺钉固定的稳定性，为临床应用提供理论依据。方法：取5具新鲜冷冻人体颈椎标本C1～C5，用牙托粉和螺钉固定C1和C2-C5，保留C1-C2之间的活动．切断寰椎横韧带和齿状突，造成寰枢关节不稳定，每个标本依次行前路单侧、前路双侧、Margel单侧、Margel双侧侧块螺钉固定：在生物力学试验机上应用位移控制法测定6种状态下的稳定性，前屈和侧屈的位移定值为1mm．旋转角度为3&#176;。测定完好标本、损伤后及各种内固定下在前屈、双侧侧屈和旋转状态下的刚度．比较其稳定性。结果：所有内固定组的刚度均明显高于损伤组及完好组的刚度，前路双侧侧块螺钉和后路双侧侧块螺钉固定的稳定性无明显差异。前路双侧侧块螺钉固定在前屈、左侧屈、右侧屈、旋转时的稳定性高于前、后路单侧侧块螺钉：前路单侧侧块螺钉与后路单侧侧块螺钉固定的稳定性无明显差异。结论：前、后路双侧侧块螺钉固定效果好，可单独应用于临床；而单侧侧块螺钉稳定性不足，术后需加用外固定。     

寰椎一体式椎板钩与枢椎椎板钉组合应用于非对称内固定生物力学研究

目的本文报道设计一新型寰枢椎内固定组合,并在尸体标本进行生物力学试验,有一定的临床指导意义。方法将6具新鲜尸体颈椎标本置于2Nm载荷下,运用脊柱三维运动测量系统测量C1-2节段的三维运动范围(Range Of Motion,ROM),并将之进行两两对比。实验依完整组、失稳组、双侧寰椎侧块螺钉联合枢椎椎弓根螺钉内固定(Harms技术)组、寰椎侧块螺钉联合单侧枢椎椎板螺钉+对侧枢椎椎弓根螺钉固定组、一侧寰椎一体式椎板钩+枢椎椎板钉联合对侧寰椎侧块螺钉+枢椎椎弓根螺钉内固定组的顺序进行。结果失稳组ROM较完整组显著增加,内固定后ROM显著减小,三种内固定组中:寰椎侧块螺钉联合单侧枢椎椎板螺钉+对侧枢椎椎弓根螺钉固定组在旋转和侧屈方向上具有最小的ROM,双侧寰椎侧块螺钉联合枢椎椎弓根螺钉内固定组在屈伸运动方向上有最小的R0M。一侧寰椎一体式椎板钩+枢椎椎板钉联合对侧寰椎侧块螺钉+枢椎椎弓根螺钉内固定组ROM在旋转、侧屈以及屈伸方向上均较另外两组大,但差异均无统计学意义。结论寰椎一体式椎板钩与枢椎椎板钉组合非对称内固定可提供良好的生物力学稳定性。     

前后路经 C1、2关节突螺钉固定后生物力学比较简

目的比较前后路经C1、2关节突螺钉固定的效果,并测定经双侧关节突螺钉固定后的稳定性,为临床操作提供理论依据。方法采用南方医科大学解剖教研室提供的8具新鲜冷冻人体颈椎标本（包括颅底骨-T1椎体）,切断寰椎横韧带和齿状突,制成寰枢关节不稳损伤模型,每个标本分别行正常标本、寰枢关节不稳标本、前路双侧C1、2关节突螺钉固定标本及后路双侧C1、2关节突螺钉固定标本行三维运动范围测定。结果所有内固定组的三维运动范围均明显小于损伤组及完好组,前路经1、2、关节突螺钉和后路经C1、2关节突螺钉固定的稳定性无昵显差异。结论前、后路双侧经C1、2关节突螺钉固定后明显提高椎体三维稳定性,是临床上可靠的固定方法。     

Evaluation of biomechanical properties of anterior atlantoaxial transarticular locking plate system using three-dimensional finite element analysis

Purpose

To evaluate a new anterior atlantoaxial transarticular locking plate system using finite element analysis.

Methods

Thin-section spiral computed tomography was performed from occiput to C₂ region. A finite element model of an unstable atlantoaxial joint, treated with an anterior atlantoaxial transarticular locking plate system, was compared with the simple anterior atlantoaxial transarticular screw system. Flexion, extension, lateral bending, and axial rotation were imposed on the model. Displacement of the atlantoaxial transarticular screw and stress at the screw–bone interface were observed for the two internal fixation systems.

Results

Screw displacement was less using the anterior atlantoaxial transarticular locking plate system compared to simple anterior atlantoaxial transarticular screw fixation under various conditions, and stability increased especially during flexion and extension.

Conclusions

The anterior atlantoaxial transarticular locking plate system not only provided stronger fixation, but also decreased screw-bearing stress and screw–bone interface stress compared to simple anterior atlantoaxial transarticular screw fixation.     

Atlantoaxial fusion using anterior transarticular screw fixation of C1–C2: technical innovation and biomechanical study

This study is an attempt to describe a new technique for anterior transarticular screw fixation of the atlantoaxial joints, and to compare the stability of this construct to posterior transarticular screw fixation with and without laminar cerclage wiring. Nine human cadaveric specimens were included in this study. The C1–C2 motion segment was instrumented using either anterior transarticular screws (group 1), posterior transarticular screws alone (group 2), or posterior screws with interlaminar cerclage wires (group 3). Using an unconstrained mechanical testing machine, the specimens were tested in rotation, lateral bending, and flexion-extension using nondestructive loads of ±2 N m. The specimens were also tested in translation using nondestructive loads of ±100 N. All values for the three groups with regards to anterior-posterior displacement, rotation, and lateral bending were similar as determined using a Kruskal–Wallis rank sum test with a significance level of p<0.05. The only significant difference was registered in flexion-extension where the cerclage wire added some strength to the construct. Anterior transarticular screw fixation of the atlantoaxial spine has several advantages over posterior fixation techniques, and is as stable as posterior transarticular fixation in all clinically significant planes of motion. The addition of posterior interlaminar cerclage wiring further improves resistance to flexion-extension forces. Anterior transarticular screw fixation of the atlantoaxial joint is a useful technique for achieving C1–C2 stabilization.     

Biomechanical study of angle-stable anterior atlanto-axial spondylodesis plate

The optimum fixation method to achieve atlantoaxial fusion after odontoid resection is still subject to discussion. Isolated posterior surgical procedures for treatment of irreducible atlantoaxial kyphosis with spinal cord compression are associated with a high rate of morbidity and mortality. Transoral atlantoaxial plate fixation has been described by Harms as a fixation technique after odontoid resection. The purpose of this study was to compare biomechanically a new anterior atlantoaxial locking plate (AALP) with the Harms plate and the atlantoaxial transarticular screw fixation described by Magerl. Sixteen human cadaver craniocervical specimens were tested in flexion, extension, rotation, and bending with a nondestructive flexibility method using a nonconstrained testing apparatus. Five different groups were examined: (1) control group (intact) (n = 16), (2) unstable group (after dissection of the atlantoaxial ligaments and odontoidectomy) (n = 16), (3) Harms group (transoral atlantoaxial plate fixation) (n = 8), (4) AALP group (anterior atlantoaxial locking plate fixation) (n = 8), and (5) Magerl group (transarticular atlantoaxial screw fixation) (n = 16). Stiffness in any direction was significantly higher in the AALP specimens and those fixated with the Magerl method than in the Harms, control, or unstable specimens. The difference in stiffness between the AALP and Magerl reconstruction groups was not statistically significant. Experimentally, the AALP was significantly stiffer than the Harms plate. The AALP provided stiffness equal to transarticular screw fixation according to Magerl. A question that cannot be answered by this in vitro study concerns the level of rigidity required to obtain long-term stability and fusion by atlantoaxial fixation methods. However, it may be assumed that the more spinal motion is eliminated the greater the chance of definite spinal fusion. Therefore, it seems reasonable that the most reliable and rigid fixation method would be the method of choice.     

前路经枢椎体至寰椎侧块螺钉内固定三维稳定性的实验研究

目的：评价前路经枢椎体至寰椎侧块螺钉内固定三维稳定性。方法：16具成人标本（C0–C3）,对每一标本分别测定完整状态（第1组）、齿状突Ⅱ型骨折（第2组）、后路经关节螺钉内固定术（Magerl技术）（第3组）、前路经枢椎体至寰椎侧块螺钉内固定（第4组）4种状态下的三维运动范围,并进行统计学分析。结果：1组与其他3组、2组与其他3组比较差异有统计学意义（P〈0.001）。前路经枢椎体至寰椎侧块螺钉内固定与后路Magerl螺钉内固定均能显著减少寰枢关节各方向运动范围,两种固定方法差异无统计学意义（P〉0.05）。结论：前路经枢椎体至寰椎侧块螺钉内固定的三维稳定性与后路Magerl螺钉内固定术相当,为寰枢椎不稳定及脱位患者的治疗提供了一种可靠的手术选择。     

Biomechanical assessment of transoral plate fixation for atlantoaxial instability

STUDY DESIGN: In an experimental study using human cadaver specimens the biomechanical data of anterior atlantoaxial plating according to Harms were evaluated. OBJECTIVES: The purpose of this study was to evaluate this method biomechanically. SUMMARY AND BACKGROUND DATA: The optimum fixation method to achieve fusion at the atlantoaxial joint after odontoid resection is still a matter of discussion. Isolated posterior surgical procedures for treatment of irreducible atlantoaxial kyphosis with spinal cord compression are associated with high rates of morbidity and mortality. Transoral atlantoaxial plate fixation has been designed by Harms as a fixation technique after odontoid resection. In a modification, this procedure has been combined with the posterior wire fusion according to Brooks. METHOD: Eight human cadaver craniocervical specimens were tested in flexion, extension, rotation, and bending with a nondestructive flexibility method using a nonconstrained testing apparatus. Five different groups were examined: 1) control group (intact); 2) unstable group (after dissection of the atlantoaxial ligaments and odontoidectomy), 3) Harms group (transoral atlantoaxial plate fixation) 4) Harms-Brooks group (transoral atlantoaxial plate fixation and dorsal atlantoaxial wire fixation); and 5) Magerl group (transarticular atlantoaxial screw fixation). In a second experimental series, failure loads of the Harms-Brooks and the Magerl fixation methods were determined. RESULTS: The angular displacement of the Harms-Brooks group and the Magerl group was less than in any other group. Stiffness values at 0-3.0 Nm loads in any direction were larger for the Harms-Brooks-and Magerl-fixated specimens than for the Harms, control, or unstable specimens. No statistically significant difference was observed between Harms-Brooks and Magerl reconstruction stiffness. Ultimate failure load in the Harms-Brooks group was higher than in the Magerl group. CONCLUSIONS: Experimentally, isolated anterior atlantoaxial plating was less stable than the combined reconstruction procedures. Transoral plate fixation according to Harms in combination with posterior wire fixation according to Brooks provided a failure load and stiffness equal to transarticular screw fixation according to Magerl.     

Biomechanical comparison of five different atlantoaxial posterior fixation techniques

STUDY DESIGN: Five different reconstructions of the atlantoaxial complex were biomechanically compared in vitro in a nondestructive test. OBJECTIVES: To determine whether non-bone graft-dependent one-point fixation affords stability levels equivalent to three-point reconstructions. SUMMARY OF BACKGROUND DATA: Previous investigations have demonstrated that three-point fixation, using bilateral transarticular screws in combination with posterior wiring, provide the most effective resistance to minimize motion around C1-C2. However, placement of transarticular screws is technically demanding. Posterior wiring techniques affording one-point fixation have failure rates of approximately 15%, with failure considered to be secondary to structural bone graft failures. One-point, non-bone graft-dependent fixations have not been tested. METHODS: Eight human cervical specimens, C0-C3 were loaded nondestructively. Unconstrained three-dimensional segmental motion was measured. The reconstructions tested were two one-point fixations, one two-point fixation, and two three-point fixations. RESULTS: Under axial rotation two and three-point reconstructions provided better stiffness than the one-point reconstructions (P < 0.05). During flexion-extension, higher stiffness levels were observed in one- and three-point fixations when compared with the intact spine (P < 0.05). In lateral bending no significant differences were observed among the six groups, although the trend was that reconstructions including transarticular screws provided greater stability than one-point fixations. CONCLUSION: The current findings substantiate the use of three-point fixation as the treatment of choice for C1-C2 instability. [l: atlantoaxial fixation, biomechanics, cervical spine, instability, spinal instrumentation, transarticular screws]     

不同入路减压内固定治疗胸腰椎爆裂骨折

目的 探讨不同入路减压内固定治疗胸腰椎爆裂骨折的疗效.方法 将92例胸腰锥爆裂性骨折患者根据病情和患者知情同意分为两组：后路短节段椎弓根螺钉内固定融合术47例,前路减压钛网植骨内固定术45例.对两种治疗方式的疗效进行比较.结果 两组均获满1年随访.两组患者的神经功能均好转;两组患者治疗1年后较治疗前的椎体前缘高度、Cobb角均有明显改善（P〈0.05）;治疗后两组间椎体前缘高度、Cobb角比较差异无统计学意义（P〉0.05）;两组均无顽固性腰痛及内固定断裂等并发症发生.结论 后路短节段椎弓根螺钉内固定融合术和前路减压钛网植骨内固定术治疗胸腰椎爆裂骨折均可取得较好效果.     

下颈椎后路3种固定技术的拔出强度研究

目的评价下颈椎后路侧块螺钉、椎弓根螺钉、经关节螺钉3种固定方法的拔出强度。方法6具新鲜颈椎尸体标本（C3～C7）,分别用侧块螺钉Roy-Camille法（LMS）、椎弓根螺钉（TPS）和经关节螺钉植入法（TAS）拧入螺钉,使用万能材料实验机,以100、200、300、400、500、600N分级加载,以18mm/min加载速度进行螺钉拔出实验,测试其最大拔出力、最大拔出能量。结果LMS最大拔出力为（426±38）N,最大拔出能量为（5.26±0.39）J;TPS最大拔出力为（502±42）N,最大拔出能量为（7.18±0.67）J;TAS最大拔出力为（482±40）N,最大拔出能量为（6.68±0.47）J。LMS的最大拔出力和最大拔出能量均小于TPS和TAS（P〈0.05）,而TPS和TAS之间相近,差异无统计学意义（P〉0.05）。结论经关节螺钉拔出强度优于侧块螺钉,而椎弓根螺钉拔出强度最大。     

枕颈部后路不同内固定的生物力学比较

目的评价不同内固定重建枕颈部稳定性的生物力学性能。方法12具新鲜人体枕颈部标本,在标本完整、枕寰枢不稳、枕颈部植骨块钛缆固定(A组)、枕颈部经关节螺钉内固定(B组)、SUM-MIT枕颈部内固定系统固定(C组)五种状态下,依次用脊柱三维运动测量系统测试其OcC1、C1,2节段的运动参数。同时对固定后的OcC1经关节螺钉(OcC1TA组)、C1,2经关节螺钉(C1,2TA组)、枢椎椎弓螺钉(C2IS组)和枕骨螺钉(Oc Screw组)在生理载荷下三维六自由度运动时,运用电测法测定四种螺钉的拔出应力,并行统计学分析。结果在OcC1节段,B组在屈伸运动中的运动范围和中性区显著大于C组。在侧屈和旋转运动中,A组的运动范围和中性区均明显大于B、C组。在C1,2节段,B组各方向运动的运动范围和中性区均明显小于A组。B组在旋转运动中的运动范围和中性区均显著小于C组。电测法结果显示,侧屈状态下所有螺钉局部应变均接近0;前屈和旋转时螺钉承受不同程度的拉应力,后伸时螺钉承受压应力。Oc Screw组在屈伸和旋转运动状态下,所承受的任何载荷应力均大于其他三种置钉方法。结论枕颈部后路经关节螺钉内固定和SUMMIT枕颈内固定在控制旋转和侧屈的稳定性上有优点。枕骨螺钉承受的拉应力最大,生理环境下枕骨螺钉可能更易发生松动和断裂。