颈椎前路静力性与动力性钉板系统在三柱不稳定损伤中生物力学性能的比较

目的比较颈椎前路静力性、动力性钉板系统在三柱屈曲牵张型不稳定损伤中的生物力学测试结果，为临床提供生物力学依据。方法采用6具小牛颈椎标本，在C4、5节段制作屈曲牵张损伤模型，切除椎间盘、植骨后，随机分为3组，分别采用Orion、Codman、Window钢板螺钉固定，分别测定正常颈椎及固定后脊柱在前屈、后伸、旋转运动时的稳定性并与正常标本比较。结果3种钢板固定后的活动度（ROM）与正常颈椎相比要大。其中Orion在前屈、后伸、侧屈与正常相比无显著的差异（P〉0．05）；Codman和Window在前屈、后伸时与正常相比有显著的差异（P〈0．05）；Codman在侧屈时正常相比无显著的差异（P〉0．05），Window侧屈时与正常相比有显著的差异（P〈0．05）；3种钢板在旋转时与正常相比均有显著的差异（P〈0．05）。结论在三柱屈曲牵张型不稳定损伤的模型中，前路静力化固定相对稳定，动力化固定可能降低一定的固定强度，尤其是选择平移类设计的钢板固定应慎重。     

颈椎前路静力性动力性钉板系统在单椎间减压植骨融合中的生物力学研究

[目的]比较颈椎前路静力性、动力性钉板系统在颈椎前路单椎间减压植骨融合中的生物力学,为临床应用提供生物力学依据.[方法]采用6具小牛颈椎标本,测定其正常颈椎C4、5节段的活动范围(ROM) ,而后在C4、5节段制作单椎间减压植骨融合模型后随机分为3组,分别采用Orion、Codman、Window钢板、螺钉固定,分别测定脊柱在前屈、后伸、旋转、侧屈运动时的稳定性并与正常标本比较.[结果]单椎间减压植骨融合后,无论采用哪种钢板固定,其术后ROM值除侧屈时稍大外均比正常颈椎要小,在前屈时最为明显(P< 0.05);后伸时Orion固定最接近正常标本(P> 0.05),而Codman、Window与正常标本相比有较大差异(P< 0.05);旋转侧屈时3 种钢板与正常颈椎均无显著性差异(P> 0.05);3 种钢板之间无显著性差异(P> 0.05) .[结论]在颈椎前路单椎间减压植骨融合中,颈前路静力性、动力性钉板系统均能维持颈椎的稳定性.本试验支持动力性钉板系统在颈椎前路单椎间减压植骨融合中应用.     

寰枢椎前路侧块螺钉内固定的生物力学测试

目的比较寰枢椎前路侧块螺钉和前路钛网、前路钢板内固定后颈椎标本的稳定性,分析不同前路内固定方法对寰枢椎各个方向运动的控制作用,为临床选择应用提供参考。方法 5具新鲜冷冻保存的尸体标本,快速分离出C0～T1节段,去除表面肌肉组织,放射测定,排除骨溶解、骨折及有其他病变的标本,以自凝型牙托粉包埋C2～7节段。包埋好的标本以特殊夹具固定于三思牌测力机上进行前屈、后伸和左右侧屈刚度的测试。旋转刚度在自制的测力机上测定。结果与正常组和损伤组相比,三种内固定方法均能明显提高寰枢椎各向活动的刚度,统计检验P<0.05;术式间的比较前路螺钉组的活动刚度明显高于前路钢板(各个方向P<0.05)和前路钛网(各个方向P<0.05);前路钢板的活动刚度明显高于前路钛网(各个方向P<0.05)。结论体外颈椎标本的生物力学实验表明,无论与正常组或损伤组相比前路双侧块螺钉、前路钢板和前路钛网内固定均能提高寰枢椎的稳定性,其中前路双侧块螺钉内固定提供的稳定性最强,与简单外固定配合使用可满足临床需要,当必须行寰枢椎前路内固定时应优先考虑使用。前路钢板和前路钛网单独使用稳定性较差,虽与后路内固定术式联用或改进设计可提高稳定性,但提高了并发症风险和经济负担。     

颈前路Uniplate与Orion钢板单间隙固定生物力学研究

[目的]比较颈前路单椎间隙减压植骨融合Uniplate与Orion钢板同定目的稳定性,为临床提供生物力学依据.[方法]采用6具小牛颈椎标本,依次进行3组实验.测定正常颈椎C4、5活动范围(ROM)作为对照,制成C4、5椎间盘切除、植骨、Orion、Uniplate钢板固定模型,依次测试相应目的ROM,转化为稳定指数(Sf).[结果]Uniplate钢板组Sf与正常比,前屈时Sf,增加21%,差异有显著性(P＜0.05);后伸旋转时比正常增大11%、1%,侧屈时比正常减少9%,差异无显著性(P＞0.05).Uniplate钢板组Sf与Orion钢板组比近似,甚至增加,差异尤显著性(P＞0.05).[结论]Uniplate钢板固定颈前路单椎间减压植骨融合稳定性较好,且临床操作简便.     

四种颈椎前路钢板的临床应用比较

目的 探讨叫种颈椎前路钢板的优缺点及临床应用价值.方法 采用Caspar、Codman、AO(CSLP)及Orion四种颈椎前路钢板行颈前路植骨加钢板内固定治疗颈椎疾患145例,随访6～18个月,观察各固定系统的稳定性、融合率及并发症.结果 93.7%(136/145例)患者神经功能获得不同程度的恢复.4种钢板螺钉固定系统融合率无显著差别,术后无钢板螺钉断裂、松动、植骨块脱出等并发症.结论 四种颈前路钢板对稳定颈椎、促进植骨融合、恢复和维持椎间高度及生理曲度均具有积极意义.Orion钢板螺钉系统固定效果更好,且更易操作.     

颈椎前路钛网钢板内固定及自体髂骨植骨在不同颈椎节段中的生物力学研究

目的 采用颈椎前路钛网钢板及自体髂骨植骨对不同颈椎节段进行内固定，分析其生物力学改变。方法 取自愿捐赠的6具新鲜尸体C3～7标本，C5、C5.6及C4～6椎体次全切除后，分别行髂骨植骨和钛网前路钢板内固定术，测量各节段的前屈、后伸、左、右侧弯及左、右旋转运动变化，以完整标本作为对照组。结果 自体髂骨的植入使失稳颈椎的稳定性提高，其侧弯、屈伸运动度减少，与对照组比较，差异有统计学意义（P〈0．05），但抗旋转运动减少不明显（P〉0．05）。不同颈椎节段开槽减压椎间撑开钛网前路钢板内固定状态下，手术节段的即刻稳定性比对照组及撑开植骨状态增加（P〈0．05）。结论 颈椎前路椎体次全切除之后，植骨仅能部分改善其稳定性，但应用颈椎前路钛网钢板内固定可明显增强颈椎的稳定性，也较完整颈椎运动功能单位稳定。     

前路椎体撑开后颈椎三维活动度测量

目的：旨在研究颈椎前路椎体撑开椎管扩大后对颈椎运动稳定性的影响，以求为新的术式设计提供实验参数。方法：采用新鲜尸体标本8具，于C5椎体正中部分切除开骨槽10mm，撑开骨槽达15mm后植入楔形骨块维持，AO前路带锁钢板固定C4一C6节段，分别对正常、撑开植骨及AO前路带锁钢板固定3种状态进行脊往三维运动测量与稳定性分析。结果：颈椎椎体撑开后，与正常组相比，除后伸运动范围稍增大外，其余运动范围均减小；前路钢板固定后三维运动范围均显著减小。结论：颈椎前路椎体撑开椎管扩大后，相应椎节活动废减小，稳定性增加，即刻恢复稳定应行前路内固定。     

生物衍生肌腱双侧关节突交叉固定动力重建颈椎后柱动态稳定性的体外生物力学研究

目的对于颈椎后柱不稳定进行动态稳定性重建研究鲜有报道。探讨采用冻干处理的生物衍生肌腱动力重建颈椎后柱动态稳定性的生物力学性能。方法收集死亡捐献者残肢掌长屈肌腱及掌伸肌腱制备生物衍生肌腱。20个新鲜成年山羊颈椎标本(C1～7),随机分为4组,每组5个标本。A组为完整标本组,B组为损伤模型组,C组为后柱钉棒固定组,D组为肌腱动力重建组。B、C、D组通过破坏颈椎后方韧带复合体制作屈曲分离型损伤模型,C组用侧块螺钉经后路固定,D组用生物衍生肌腱行侧块经关节突交叉固定。用脊柱三维运动测量系统测算各组标本C3、C4节段前屈、后伸、侧屈、旋转的运动范围(range of motion,ROM)。结果前屈运动:C组ROM明显小于其他3组,差异有统计学意义(P<0.05);B组ROM较A、D组明显增加,差异有统计学意义(P<0.05);A、D组间比较差异无统计学意义(P>0.05)。后伸、侧屈、旋转运动:C组ROM明显小于其他3组,差异有统计学意义(P<0.05);其他3组间比较差异无统计学意义(P>0.05)。结论新鲜成年山羊颈椎标本行生物衍生肌腱侧块经关节突交叉固定,能够限制颈椎过度前屈,完全保留后伸运动,不限制侧屈和旋转运动,重建屈曲分离型损伤下颈椎的动态稳定性。     

四种颈椎前路钢板在颈椎融合手术中应用和比较

目的:观察和比较4种颈椎前路钢板在颈椎前路融合手术中的优点和不足.方法:101例颈椎病、颈椎后纵韧带骨化症(OPLL)无骨折脱位型颈髓损伤患者进行前路椎间盘减压、植骨融合同时分别采用AO、Caspar、Orion和Zephire颈椎前路固定系统固定.与单纯植骨融合组比较手术时间、出血量、术后并发症、术后症状体征缓解程度和融合情况.结果:患者症状特征术后明显改善;未发现手术并发症,颈椎前路钢板固定组融合率明显优于单纯植骨融合组.结论:4类钢板均能提供充分的颈椎稳定性,使用安全,Zephire钢板较其余钢板系统使用更为简便.     

四种颈椎前路钢板在颈椎融合手术中应用和比较

目的：观察和比较4种颈椎前路钢板在颈椎前路融合手术中的优点和不足。方法：101例颈椎病、颈椎后纵韧带骨化症(OPLL)无骨折脱位型颈髓损伤患者进行前路椎间盘减压、植骨融合同时分别采用AO、Caspar、Orion和Zephire颈椎前路固定系统固定。与单纯植骨融合组比较手术时间、出血量、术后并发症、术后症状体征缓解程度和融合情况。结果：患者症状特征术后明显改善；未发现手术并发症，颈椎前路钢板固定组融合率明显优于单纯植骨融合组。结论：4类钢板均能提供充分的颈椎稳定性，使用安全，Zephire钢板较其余钢板系统使用更为简便。     

Distractive flexion injuries of the subaxial cervical spine treated with anterior plate alone

The clinical and radiographic effect of anterior plate fixation alone was evaluated in 36 consecutive patients with distractive flexion (DF) injuries in the lower cervical spine. Mean follow-up time was 15 months. The aim of the present study was to determine whether anterior plate fixation alone provides sufficient stability when treating DF injuries in the cervical spine. Solid union was seen in 6 of 6 patients with stage 1 injury and in 15 of 17 patients with stage 2 injury. In the patients with stage 3 injury, 7 of 13 of the anterior fixations failed. These failures occurred mainly among the patients with severe neurologic injuries. We believe these findings substantiate the use of anterior plate alone for DF injuries at stage 1 and 2 but disqualify anterior plate fixation alone for DF injuries at stage 3, with neurologic injury present.     

Internal fixation of cervical trauma following corpectomy and reconstruction. The effects of posterior element injury

Although biomechanical data indicates that anterior fixation alone in unstable cervical injuries may not provide adequate stability, reports of clinical series indicate general success with this method of treatment. The specific contribution of posterior column injury to overall stability following reconstruction has not been evaluated. This study examined the biomechanical stability of anterior and/or posterior plate fixation following anterior corpectomy and reconstruction for unstable cervical injuries with varying degrees of posterior element injury. The C4-C6 motion segments of ten fresh frozen bovine cervical spines were used. After mounting, nondestructive mechanical testing in axial compression, torsion, flexion, extension, and lateral bending was done as an intact control. A C5 corpectomy with reconstruction using a synthetic bone graft was performed and the posterior ligaments sectioned at the C5-C6 level. Each specimen was sequentially instrumented with anterior and posterior plating alone and in combination and each construct was mechanically retested. The specimens were then further destabilized by bilateral facetectomies at C5-C6 and again tested with the same instrumentation combinations. In comparison to the controls, the spines with a C5 corpectomy/bone graft and posterior ligament rupture with anterior plating demonstrated significantly increased stiffness in flexion, extension, and lateral bending; posterior plating increased stiffness in only flexion and lateral bending. In axial compression and torsion, anterior or posterior plating demonstrated stiffness similar to the controls. Further destabilization by facetectomy significantly decreased stiffness of the instrumented construct (less than control) in torsion with anterior or posterior plate fixation alone. Combined plating showed increased stability compared to controls in all loading conditions for both patterns of instability. Anterior plating alone was able to restore the stability of the cervical spines with posterior ligamentous injury after corpectomy, but it failed to do so with the addition of bilateral facetectomies. For the unstable cervical spine with significant bilateral loss of posterior bony contact, anterior or posterior plating alone may not provide sufficient stabilization in the absence of any additional external immobilization. Combined plating should be considered, which may obviate the need for external immobilization.     

Spinous process wiring versus lateral mass fixation for the treatment of anterior cervical pseudarthrosis: a biomechanical comparison

Our objective was to compare the stiffness of lateral mass screws versus two different spinous process wiring constructs in a cadaveric model of plated anterior cervical pseudoarthrosis. When treating an anterior plated pseudoarthrosis via a posterior approach, it is unclear whether the added expense, muscle exposure, and risk of lateral mass fixation are justified biomechanically versus a simpler, cheaper, and potentially less morbid wiring technique, because the presence of the anterior plate likely reduces motion over the unplated situation. Seven cadaveric cervical spines were loaded in compression, flexion, extension, lateral bending, and torsion. Each load sequence was applied to: 1) the intact spine; 2) after application of a plated ACDF construct (pACDF); and 3) after the insertion of lateral mass (LM) screws, ``modified' triple wiring (TW), or Roger's wiring (RW), in alternating order for each specimen. For each sequence, load deformation curves and stiffness were obtained. Supplemental LM fixation significantly (p ≤ 0.05) increased stiffness versus pACDF in all six modes tested. TW significantly increased stiffness versus pACDF in compression, flexion, and torsion, but not in extension, or lateral bending. RW significantly increased stiffness versus pACDF only in axial torsion. When comparing LM to the wiring constructs, LM fixation was significantly stiffer than RW in flexion, extension, and lateral bending; LM fixation was stiffer than TW in lateral bending. LM fixation produced the stiffest overall constructs in stabilizing a plated pseudarthrosis ACDF model. It was significantly stiffer in more modes versus RW than TW.     

Orion锁定型颈椎前路钢板系统的临床应用

目的 探讨Orion负定型颈椎前路钢板系统对颈椎骨折和脊髓型颈椎病手术固定的效果。方法 对3例颈椎骨折合并高位截瘫和2例脊髓型颈椎病患者施行颈椎前路减压植骨融合及Orion钢板内固定。结果 术后随访4－12个月,植骨已完全融合,无钢板断裂、螺钉松动等情况发生。结论 Orion锁定型颈椎前路钢板系统方法简单、容易掌握,内固定牢固,尤其适用于颈椎骨折伴高位截瘫患者的内固定治疗。     

颈椎屈曲牵张性损伤的前路手术复位与固定

目的 利用前路手术复位、固定治疗颈椎屈曲牵张性(DF)损伤，总结其临床疗效并探讨其适应证。方法 回顾总结29例颈椎DF损伤病例，结合术前影像检查按Allen法评定损伤分期，按ASIA标准评定神经损伤程度。所有病例术前均未做牵引复位，采取早期(伤后72h内)颈前路脱位椎间撑开结合撬拨技术复位，再以自体髂骨植骨、前路带锁钢板内固定治疗。观察手术效果，评估神经功能恢复情况。结果 随访6～18个月，效果满意。29例患者中2例DF1期，均无神经损伤；17例DF2期，10例不全性神经损伤，其余均不伴神经损伤；10例DF3期，2例不全性神经损伤，8例完全性神经损伤。术前MRI检查显示6例合并椎间盘损伤(26％)，其中DF2期2例，DF3期4例。所有DF2期与8例DF3期患者术中成功复位，2例DF3期改行后路复位。本组无发生手术及内固定相关并发症，3例术后出现神经损伤短期内加重现象。结论 颈椎DF损伤时采用前路减压复位技术能安全、有效地恢复解剖序列，结合应用前路钢板，能取得良好疗效，尤其适用于DF 1、2期损伤的病例。     

Anterior cervical plating reverses load transfer through multilevel strut-grafts

STUDY DESIGN: In vitro biomechanical study using a programmable testing apparatus that replicated physiologic flexion/extension cervical spine motion and loading mechanics. OBJECTIVE: To determine the influence of anterior plating on multilevel cervical strut-graft mechanics in vitro. SUMMARY OF BACKGROUND DATA: The addition of anterior instrumentation does not prevent construct failure in multilevel cervical corpectomy. METHODS: Six fresh human cadaveric cervical spines (C2-T1) were tested in the four following sequential conditions: harvested, C4-C6 corpectomy, strut-grafted, and strut-grafted with an anterior cervical plate. A force-sensing strut-graft was used to measure compression/tension, flexion/extension and lateral bending moments, and axial torsion. Parameters of stiffness, vertebral motion, and strut-graft loads were compared to determine differences between the four spine conditions. RESULTS: Application of the anterior plate significantly increased the global stiffness (P < 0.01) and decreased the local motion (P < or = 0.01) of the instrumented levels (C3-C7). Flexion of the strut-grafted spine loaded the strut-graft, whereas extension unloaded the strut-graft. With the anterior plate, flexion of the plated spine unloaded the strut-graft. Extension significantly loaded the strut-graft more than similar degrees of flexion in the strut-grafted condition (P = 0.01). Strut-graft loading end limits of 225 N were reached with a mean 7.5 degrees extension in the plated spines. CONCLUSIONS: Anterior multilevel cervical plating effectively increases stiffness and decreases local cervical motion after corpectomy. However, anterior cervical plating also reverses graft loads and excessively loads the graft in extension, which may promote pistoning and failure of multilevel constructs.     

Lumbar lateral interbody cage with plate augmentation: in vitro biomechanical analysis

Many studies have concluded that stand alone cages provide limited stabilization to the spine, and this primary stabilization decreases postoperatively due to various factors. A supplemental fixation may, therefore, be needed to improve the stability. Extensive biomechanical analysis was performed in the present study to further evaluate the stabilization achieved by a laterally inserted cage and the role of an anterior lateral supplemental fixation. Eight human cadaver functional spinal units were subjected sequentially to four different test conditions: (1) intact, (2) instrumented laterally with a long cylindrical threaded cage, (3) the same cage supplemented with a lateral fixation plate, the plate being firmly connected to the cage, and (4) removal of the connection between the plate and the cage. Pure moments were applied to each specimen in a quasi static manner, ranging from -7 Nm to 7 Nm in flexion/extension, lateral bending and axial rotation. Three-dimensional segmental motions were simultaneously recorded under each loading condition. Statistical analysis was carried out on the motion parameters, including the range of motion (ROM) and the neutral zone (NZ). Inter-group comparisons were made using the Friedman test and the Wilcoxon test. The results showed that the stand alone lateral cage provided stabilization by increasing segmental stiffness above that of the intact spine. The stiffness increase ratios were: 1.6 in flexion/extension ( P=0.07), 1.3 in lateral bending ( P=0.4) and 1.0 in axial rotation ( P=0.67). A supplemental plate provided significant reinforcement of the stabilization. The stiffness increase ratios relative to the intact spine were: 3.1 in flexion/extension ( P=0.012), 5.0 in lateral bending ( P=0.012) and 2.3 in axial rotation ( P=0.012). After removal of the connection between the cage and the plate, the stiffness ratios were: 2.7 in flexion/extension ( P=0.027), 4.6 in lateral bending ( P=0.027) and 2.1 in axial rotation ( P=0.027). Globally, the cage alone increased the segmental stiffness above that of the intact spine by a factor of 1.1 ( P=0.39), with the supplemental plate, segmental stiffness increased by a factor of 3.1 ( P<0.01), and the unconnected cage/plate increased stiffness by a factor of 3.0 ( P=0.02). Supplementation of the lateral cage with an anterolateral plate was thus shown to provide significant additional stabilization in all directions, which may potentially compensate for the postoperative decrease in segmental stability.     

Biomechanical comparisons of spinal fracture models and the stabilizing effects of posterior instrumentations

In this study, the authors evaluated the stiffness of motion segments in intact spines in two spine fracture models, and with each of five implant systems used for posterior fixation of thoracolumbar spine fractures. The devices represented a cross-section of types, including those employing sublaminar wires with and without laminar hooks, pedicle screws, plates, and rods. Two spine fracture models, one partially and one totally destabilized, were used in the tests of the instrumentation. Stiffness, or the magnitude of load needed to produce a unit displacement of the construct in the direction of the applied load, was measured in flexion, extension, lateral bending, and torsion in combination with a compressive force. Both horizontal plane shear and angular displacements were measured in the two fracture patterns. All evaluations were made by testing the difference in stiffness for statistical significance among groups. The results showed significant differences in stiffness without instrumentation among intact spines, partly destabilized spines (anterior two-thirds of disk and posterior ligaments removed), and totally destabilized spines (only anterior longitudinal ligament intact). The implant/spine constructs were least stiff relative to the intact spine in torsion, followed in increasing order of stiffness with flexion, lateral bending, and extension. In the Roy-Camille plate with six-screw fixation was found to produce the stiffest construct, followed by wired Harrington rods, C-rods and J-rods, and the Vermont internal fixator.(ABSTRACT TRUNCATED AT 250 WORDS)     

颈脊髓损伤前后路减压内固定术后稳定性研究

目的研究一期前后路联合减压治疗颈脊髓损伤的颈椎稳定性问题,从生物力学角度验证本术式的可行性。方法采集新鲜人体颈椎标本6具,不同术式自身对照,采用实验应力分析方法,测定其颈椎的生物力学特性和颈椎稳定性问题。结果采用前后路联合减压钢板内固定,无论在颈椎的强度、刚度,抗扭转强度、刚度以及在颈椎稳定性、承载能力方面均比其他对照组强,均具有显著性差异(P<0·05),而颈椎前后路联合减压单纯前路Orion钢板+植骨融合术其生物力学的各项指标均比其他对照组差。结论颈椎一期前后路联合减压治疗颈脊髓损伤的颈椎生物力学实验证明,采用前后路联合钢板内固定,颈椎非常稳定、可靠、生物力学性能优越,疗效满意;而单纯行前路Orion钢板+植骨融合术,术后早期应辅以外固定。