钛质网笼内植物加前路带锁钢板对颈椎稳定性的生物力学评价

目的评价颈椎在植入颈椎钛质网笼内植物和植入钛质网笼内植物辅助AO前路带锁钢板内固定两者的生物力学稳定性.方法测量6例新鲜人颈椎骨骼韧带标本(C2～T1)在正常、C5椎体次全切除减压后植钛质网笼内植物、植钛质网笼内植物后辅助AO前路带锁钢板内固定三种工况下C4～C6节段的三维运动数据,并做统计学处理.结果6例颈椎标本C4～C6节段在正常、植钛质网笼内植物、植钛质网笼内植物加AO前路钢板三种工况下,前屈/后伸、左/右侧弯、左/右轴向旋转的运动范围(ROM)平均值(°)分别为14.12/12.94、13.39/13.11、9.77/10.72;9.70/14.42、8.94/8.61、7.65/8.09和4.39/1.36、4.08/4.19、3.46/3.63.结论颈椎减压、植入钛质网笼后在后伸运动时的稳定性明显不足;辅助AO前路带锁钢板内固定后在各个方向的稳定性都显著增强,可满足临床应用的要求.     

AO颈椎前路带锁钢板内植物并发症

目的：探讨AO颈椎前路带锁钢板内植物并发症及其预防措施。方法：对采用AO前路带锁钢板固定治疗的颈椎疾患中经平均随访16个月的193年发生的17例并发症作了分析。结果：发生钢板放置偏斜4例次,螺钉植入椎间隙2例次,钢板未完全锁定11例次,其中超出钢板平面1－2mm7例次,2－3mm4例次,发生螺钉松动并滑脱3例次,其中2例导致食道瘘,未出现钢板螺钉断理解。结：颈椎前路带锁钢板内植物并发症的发生大多与手术医生的经验有关,合理选择手术适应证,遵循手术的生物力学原则是预防该手术并发症的关键。     

颈前路内固定钢板的生物力学研究及临床应用

1952年ＬｅｒｏｙＡｂｂｏｔｔ提出经前路手术治疗颈椎创伤、变性性疾病、感染和肿瘤等,继而Ｒｏｂｉｎｓｏｎ(1955年)和Ｓｍｉｔｈ(1958年)提出采用前路减压自体骨植入融合治疗,并由Ｃｌｏｗａｒｄ(1961年)应用此术式治疗颈椎外伤。随后这种经颈前路减压自体骨植入融合术逐渐开展起来,并在七、八十年代迅速普及。然而这种手术的缺陷在广泛的应用中也明显暴露出来,如移植骨不融合、移植骨脱出和/或塌陷、进行性颈椎后凸、脊柱排列紊乱等,主要是由脊柱不稳引起的。为克服这一缺陷,出现了内固定和外固定两种稳定方法。外固定方法主要是应用环…     

Window前路钢板在颈椎外科中的应用

目的：评价Window颈椎动力钢板系统（anterior cervical dynamic plate sysytem,ACDPS）在颈椎外科的应用效果。方法：对21例颈椎疾病患者行颈前路减压植骨融合,并采用ACDPS内固定。结果：随访6－21个月,所有病例植骨均完全愈合,无一例发生钢板螺钉断裂、松动等并发症。结论：ACDPS具有动力加压作用,内在稳定性好,固定可靠,手术简单安全。适用于颈椎外伤、退行性病变的治疗。     

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。     

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.     

颈前路钛制网状接骨板固定系统的生物力学研究

目的:对自行研制的颈前路钛制网状接骨板固定系统(ACSRP)进行生物力学评价.方法:(1)稳定测试 14例新鲜颈椎标本,随机分为A、B两组,模拟颈椎前路手术制作颈椎双间隙并部分椎体摘除的模型.分别以网状接骨板(ACSRP)和进口Caspar钢板固定,依次测量两类颈椎模型的三维运动数据;(2)植骨块的应力测试选择压力敏感胶片,分别置于A、B两组C4～C6与植入髂骨块之间,计算出其所受应力大小.结果:(1)损伤颈椎在两种钢板固定后的ROM均明显减少,稳定程度增加,但提高颈椎的稳定程度不同;(2)压敏片测量ACSRP固定后的植骨块与Caspar组间应力分布有差异.结论:ACSRP有较好的生物力学稳定作用,ACSRP固定的植骨块较Caspar组固定的植骨块有较好的应力分布.     

不同类型前路钢板固定应用于颈椎屈曲牵张型损伤的生物力学研究

目的探讨采用前路钢板固定颈椎屈曲牵张型损伤治疗的可靠性,并比较静力化固定和动力化固定等不同设计类型钢板在恢复损伤节段稳定性方面的差异。方法采用12具小牛颈椎标本,在C_(4,5)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,测试手术固定各组在颈椎前屈、后伸、侧屈及旋转运动时的稳定性并与正常标本比较。结果颈椎屈曲损伤后,无论采用哪种钢板固定,其术后运动范围(ROM值)均比正常颈椎要大。Orion固定最接近正常标本,但在旋转运动时有明显差异。Codman固定仅在侧曲时的稳定性接近正常和Orion固定组。Window固定最弱,在各运动状态下的刚度均明显低于正常组。结论在颈椎屈曲牵张型损伤时,前路静力化固定相对稳定,动力化固定可能牺牲一定的固定强度,尤其是选择平移类设计的钢板固定更要谨慎。     

对“钛质网笼内植物加前路带锁钢板对颈椎稳定性的生物力学评价”一文的看法

颈椎疾患长期以来采用前路减压植骨融合已成为典型的传统手术 ,由于其取骨需要另作切口及其可能出现的植骨块移位、不融合、椎间高度丢失等问题 ,因而不少作者在前路减压植骨的同时采用前路内固定 ,特别是近年来界面固定椎间融合器的使用 ,更是成为“时尚”。本期基础研究栏目刊载的“钛质网笼内植物加前路带锁钢板对颈椎稳定性生物力学评价”一文 ,在审稿过程中 ,专家们提出了相近或不相同的看法 ,其中一些问题值得进一步探讨。譬如 :根据本实验结果应用于临床 ,对患者究竟是“overtreatment”还是“benefit” ?单纯植骨融合是否仍可用 ?什么情况下用 ?目前笼状椎间融合器的稳定性究竞如何 ?是否需要常规加用前路钢板……等 ?     

颈椎前路环锯法减压术后三种处理方法的生物力学评价

目的 研究环锯法减压后不植骨、自体柱状髂骨植骨及螺柱状颈椎内固定器植入后,三者的生物力学稳定性,为临床手术提供依据。方法 采用新鲜青年尸体标本,分别用三种方法处理C5－6段,测量其在1．53nm的纯力矩载荷条件下的稳定性并用相邻椎体间的空间位移和卡当角表示。结果 环锯法减术后,手术节段的稳定性明显减轻。自体髂骨植入后,椎间隙高度升高,伸屈活动度下降,但其稳定性仍比正常时差。螺柱状颈椎内固定器植入,前屈、侧屈和旋转的活动度明显较正常时小,但后伸范围无明显改变。结论 环锯减压后如不植骨有可能不融合或畸形愈合。椎间植骨能明显改善减压节段的稳定性,但手术后仍应采用辅助外固定。螺柱状颈椎内固定器不但能维持椎间隙高度,防止术后畸形,而且有足够的稳定性,术后不必应用外固定。     

Cervical spine locking plate: in vitro biomechanical testing

Summary The AO cervical spine locking plate (CSLP) for anterior subaxial fixation was recently received increasing clinical acclaim, yet to date the in vitro mechanical properties of this implant have not been reported. To determine the in vitro biomechanical properties of this device, five fresh human cadaver cervical spines were subjected to nondestructive testing in flexion and torsion in three stages: stage 1: intact spine; stage 2: destabilized spine; stage 3: destabilized spine with CSLP. Stage 3 specimens were also subjected to large angular displacement testing to assess the integrity of the fixation. In flexion, mean spinous process displacement was 1.21 mm for stage 1, 3.19 mm for stage 2, and 1.37 mm, for stage 3. Mean torsional stiffness was 2.86 Nm/degree in stage 1, 1.82 Nm/degree in stage 2, and 2.20 Nm/degree in stage 3. Large angular displacement testing in stage 3 resulted in screw loosening from the bone in two specimens; no screw plate loosening occurred. In our severely destabilized in vitro model, the CSLP restored flexion stability but not rotational stability. This suggests that supplemented bracing or fixation may be required to restore torsional stability.     

Biomechanical analysis of anterior cervical spine plate fixation systems with unicortical and bicortical screw purchase

Anterior plate fixation with unicortical screw purchase does not involve the risk of posterior cortex penetration and possible injuries of the spinal cord. However, there are very few biomechanical data about the immediate stability of non-locking plate fixation with unicortical or bicortical screw placement. The aim of the present study was to evaluate the immediate biomechanical properties in terms of flexibility of a non-locking anterior plate system with 4.5-mm screw fixation and unicortical or bicortical screw purchase applied to a single destabilized cervical spine motion segment. Using fresh cadaveric cervical spine specimens C3-C7, multidirectional flexibility was measured at the level C4-C5 before and after destabilization and fixation with an anterior plate with either unicortical or bicortical screw purchase. The results showed that fixed cervical spine segments with anterior plate and bicortical screw purchase were more rigid than intact specimens in all modes of testing. The difference was statistically significant for flexion and extension (P<0.001). Plate fixation with unicortical screw purchase had statistically significant decreased ranges of motion compared to the intact specimen only in extension. Neither unicortical nor bicortical screw purchase decreased the range of motion significantly in axial rotation compared to the intact specimens. This in vitro study documented that neither unicortical nor bicortical screw purchase with non-locking plate fixation can increase stability in all modes of testing, in axial rotation in particular. Direct comparison between the group with uni- and that with bicortical screw fixation did not reveal significant differences, and therefore no advantage was shown for either type of screw fixation. Therefore, we demonstrated that both uni- and bicortical screw purchase with non-locking plate fixation can decrease immediate flexibility of the tested motion segment, with better results for bicortical purchase. No significant differences were found comparing the two groups of screw fixation. These data suggest that unicortical screw fixation can be used for anterior plate fixation with a comparable immediate stability to bicortical screw fixation.Supported by the German Research Foundation, DFG, Bonn, Germany     

Biomechanical comparison of anterior cervical spine locked and unlocked plate-fixation systems

Three different anterior plate-fixation systems are available for the stabilisation of the cervical spine: (1) the cervical spine locking plate (CSLP), (2) dynamic plates allowing vertical migration of the fixation screws, and (3) various types of plates that are secured with either monocortical or bicortical unlocked screws. Unicortical screw purchase does not involve the risk of posterior cortex penetration and possible injuries to the spinal cord. The development of locking plates with unicortical screw-fixation and intrinsic stability of the screw–plate interface, via an angle-stabilised connection, was an attempt to increase the stability of unicortical screw-fixation systems. The aim of the study was to compare the biomechanical properties of a non-locking, anterior-plate system with 4.5 mm screw fixation and a locking anterior-plate system, in a single destabilised cervical spine-motion segment. Using fresh cadaveric cervical spine specimen C3–C7, multidirectional flexibility was measured at the C4–C5 level in an unconstrained test system, before and after destabilisation and fixation with an anterior plate with either locked or unlocked screw purchase. Direct comparison of the fixed cervical spine segments with unlocked and locked anterior-plate fixation did not demonstrate significant differences. This in vitro study documented that neither locked nor unlocked anterior-plate fixation can increase stability in all modes of testing. H-plate spondylodesis with unlocked screws seems to provide sufficient mechanical integrity in most cases of monosegmental lesions.     

The cervical spine and its relation to anterior plate-screw fixation: a quantitative study

Multilevel discectomy and inter-vertebral body fusion combined with anterior plate-screw fixation is the common procedure in cervical spine surgery. The correct placement of the screws is an important factor for the outcome of these operations. Yet no systematic approach has been undertaken to optimize the geometry of the fixation-plates regarding the position of the screw-perforations. In this study MRI scans of 50 consecutive patients were analyzed regarding the height of each segment (C3–C7), the anterior–posterior diameter of the vertebral body and the distance between the vertebral arteries. Based on this data we developed Standard Spine Models. Using these models we designed two plates each for single and two-level surgery, and three plates each for three- and four-level surgery. These ten plates do fit the cervical spines of all 50 patients examined in this study. With these plates the screw-perforations could be positioned efficiently over the bodies of the concerned vertebrae. This should facilitate the selection of a plate and the positioning of the screws. Thus the surgeons might save time and the screws might be positioned more exactly and entirely in the vertebral bodies, ensuring a secure fixation.     

颈椎前路带锁钢板治疗颈椎爆裂骨折的试验及临床研究

目的 评价颈椎前路带锁钢板固定系统(CSLP)治疗颈椎骨折的稳定性及临床有效性.方法 将6具新鲜成人颈椎标本(C2～6)置于脊柱三维测量仪上测定C3～5节段的ROM,制造C4爆裂骨折,测定其三维运动变化后分别进行植骨、植骨+CSLP固定,并重复测量其三维运动.对32例下颈椎骨折行前路减压融合,并以CSLP进行内固定治疗.结果 植骨+CSLP固定后在屈伸、侧弯、旋转方向较损伤后明显下降,与正常值相比,屈伸和侧弯运动均明显减少,但旋转运动减少不明显.术后随访6～48个月,所有骨折均复位,颈椎椎体高度恢复,椎间植骨均融合,钢板位置满意,无螺钉松动或脱出.结论 AO前路钢板固定颈椎爆裂骨折时各个运动方向均能获得稳定,临床效果满意,是一种治疗颈椎骨折的理想固定装置.     

中,下颈椎纵向撞击性损伤机制的实验研究

分析人体中、下颈椎承受纵向撞击力作用时的损伤机制、损伤阈值，为颈椎撞击性损伤的防护、诊治提供生物力学依据。应用成人男性新鲜尸体标本在CZZ-Ⅱ人体撞击试验机上行撞击实验。对C2～C4标本进行30J和50J能量的撞击，对C5～T1标本进行50和100J能量的撞击，由计算机数据采集系统得到撞击力峰值、冲量、撞击速度和撞击力作用时间等参数，以放射学诊断和解剖学观察为损伤判断依据。C2～C4在轴向撞击力作用下的损伤阈值为4112～4890N或30．2～34．2N·s，C5～T1在轴向撞击力作用下的损伤阈值为4824～6362N或33．6～43．0N·s。结果表明，轴向压缩载荷引起的颈椎损伤类型与其撞击能量的大小有关，较高撞击能量会产生颈椎的整体结构破坏，较低的撞击能量仅损伤颈椎的前、中柱结构。     

Anterior decompression and plate fixation in fracture dislocations of the lower cervical spine

Summary Surgical treatment of unstable traumatic injuries of the cervical spine can be carried out by a posterior or anterior approach, with different advantages and disadvantages. Twenty patients were treated with anterior decompression, interbody fusion with autogenous iliac bone graft, and osteosynthesis with a Louis anterior plate. The screws were inserted in the vertebral body without reaching the posterior vertebral wall. There were 18 male and 2 female patients, aged between 18 and 66 years (average 36 years). The osteoarticular lesion was in 8 cases a tear-drop fracture and in 12 a fracture-dislocation. The mechanisms of injury were flexion-compression, flexion-rotation, hyperflexion, and hyperextension. A complete spinal cord lesion was present in 10 cases, central cord syndrome in 5, isolated radiculopathy in 3, and anterior cord syndrome in 1; one patient had normal neurological function. At long-term follow-up fusion of the graft was observed in all cases without evidence of spinal malalignment, breakage of the implant, or aseptic hardware loosening. Neurological deterioration was not observed in any case. In one case, complicated by late infection, healing was uneventful after plate removal, surgical debridement, and antibiotic therapy. A fistula of the hypopharynx due to perforation of the piriform recess appeared following repeated bronchoscopy 12 months after surgery. There were no signs of implant loosening and the lesion was surgically repaired. From a neurological point of view the 10 patients with complete cord lesion remained unchanged; those with incomplete cord lesions improved by 1 or 2 degrees on the Frankel scale; those with isolated radiculopathies recovered fully; and the neurologically intact patient remained unchanged. The present study and the data reported in the literature prove that anterior surgery with plate fixation in cervical spine injuries allows the achievement of complete neural decompression by direct visual examination. On the other hand, posterior surgery can result in incomplete decompression and associated neurological deterioration. Anterior plate instrumentation has proved itself mechanically adequate, even if it is less stable than posterior constructs. The advantages of anterior surgery compared to those of posterior surgery are such that several specific risks are acceptable. Posterior surgery is nevertheless indicated if the lesion cannot be reduced preoperatively under closed conditions.Read at the International Meeting of the Cervical Spine Research Society, Athens, 25th–28th June, 1992