Description of an anterior cervical osteosynthesis plate

Various authors have proposed the use of cervical osteosynthesis plates for traumatic and tumoral lesions of the cervical spine. The purpose of the plates was to maintain auto or allogenic grafts in position during biological fusion, or to act as a protection for non-biologic implants by constituting an inert framework. Among those described recently in the literature, the plates developed by Senegas, Orosco and Caspar unable osteosynthesis to occur under maximum safety conditions. The originality of the plate presented lies in its simplicity in use resulting from the oval shape of the intermediary holes this providing maximum flexibility of positioning as a function of the patient's morphology.     

Internal stress distribution in cervical intervertebral discs: the influence of an artificial cervical joint and simulated anterior interbody fusion

There is concern that cervical interbody fusion can result in accelerated degenerative changes occurring at adjacent spinal levels. The cervical spine clearly evolved to be mobile. It would seem to be desirable for spinal surgeons to have an alternative to fusion, and spinal arthroplasty is an appealing concept. The Bristol Disc is a mechanical device comprising two articulating components that result in motion with 6 df. It has been shown to have favorable kinematics when compared with intact and fused cadaveric spines. The current study attempts to record changes in the distribution of stresses within cervical intervertebral discs adjacent to the artificial disc or a simulated fusion. The technique used to measure intradiscal stress distributions is based on earlier work by McNally and Adams on lumbar intervertebral discs. The study generated stress profiles through cervical intervertebral discs statically loaded in four different postures in addition to recording changes in intradiscal pressure within both the nucleus and the annulus during flexion. Similar stress profiles were recorded from intact specimens and those with the artificial joint inserted. The artificial joint resulted in reduced stresses in the annulus compared with spines with a simulated fusion. The study demonstrates how different testing conditions can result in researchers being confronted with paradoxical data, and the simulation of muscle forces is recommended.     

The anterior cervical plate

The anterior cervical plate was employed routinely in 13 anterior cervical fusions in adults at the Medical Center Hospital of Vermont (MCHV) from October 1979 to December 1980. A method for installation of the implant is presented. Review of these patients shows that the 11 survivors have satisfactory alignment of their cervical spines, with adequately evolving fusions. Technical problems include plate position and screw depth. This demanding method is now reserved for special indications.     

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     

新型钛合金颈椎前路接骨板的三维稳定性试验

背景：目前,颈椎前路接骨板已经广泛应用于颈椎创伤、畸形、退行性变以及颈椎肿瘤的治疗。目的：应用新型钛合金研制颈椎前路多功能接骨板（multifunctional cervicalplate,MCP）,并且对其进行三维稳定性试验。方法：收集24具6个月左右宰杀的猪颈椎标本随机分为4组,每组6具标本。在连续的4种状态下,即完整状态、植骨状态、接骨板固定状态以及疲劳测试后状态,对颈椎C3-C7施加2.0Nm的纯力矩,测量标本前屈、后伸、左右侧屈、左右旋转的活动范围（rang of motion,ROM）和中性区（neutral zone,NZ）。结果：所有节段在6个方向的ROM上,MCP固定状态、MCP疲劳状态、C-mark接骨板（C-markplate,CMP）固定状态、CMP疲劳状态之间相比较,差异无统计学意义（P〉0.05）,但与完整状态、植骨状态相比较,差异均有显著统计学意义（P〈0.01）。在前屈、左右侧屈方向的ROM上,植骨状态与完整状态相比较,差异有显著统计学意义（P〈0.01）。在屈伸NZ上,MCP固定状态、MCP疲劳状态、CMP固定状态、CMP疲劳状态之间差异无统计学意义（P〉0.05）,但与完整状态、植骨状态相比较,差异均有显著统计学意义（P〈0.01）。在侧屈NZ上,除完整状态与其他状态之间有统计学意义外（P〈0.01）,其他状态之间没有差异（P〉0.05）。在旋转NZ上,所有状态之间均无统计学意义（P〉0.05）。结论：体外生物力学研究表明MCP能够给颈椎提供足够的三维稳定性,在进行扭转疲劳试验后仍然可以保持三维稳定性。     

Biomechanical effects of progressive anterior cervical decompression

STUDY DESIGN: A repeated-measures in vitro flexibility test was performed. OBJECTIVES: To determine the biomechanical functions of tissues resected during anterior cervical decompression of various extents. SUMMARY OF BACKGROUND DATA: The biomechanical consequences of discectomy have been studied in vitro, and uncovertebral joint removal has been modeled numerically. No studies have assessed the relative biomechanical contributions of different anterior column structures. METHODS: In seven human cadaver C4-T1 specimens, 20 motion segments were studied. After each destructive step, including discectomy, unilateral uncinate process removal, bilateral uncinate process removal, and posterior longitudinal ligament transection, torques were applied to four-level specimens while the angular motion was measured at each level. RESULTS: Angular range of motion and neutral zone increased by variable but statistically significant amounts after each progressive resection, most notably in flexion and extension. Each resection step caused progressively larger shifts (up to 23 mm) in the location of the axis of rotation. Uncovertebral joint resection caused the most significant changes in the observed angular coupling. CONCLUSIONS: Anterior cervical decompression significantly increases the instability and alters the kinematics of cervical motion segments. Each structure resected contributes to normal stability and kinematics, so as many structures as possible should be left intact during anterior decompression without fusion. Because flexion and extension were the modes of motion that increased most significantly after decompression, the primary function of a grafting technique or fixation device should be to limit these motions.     

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.     

颈椎前路钢板的研究进展

目前,颈椎前路钢板已广泛应用于颈椎创伤、退行性变、畸形和肿瘤患者的治疗,其能增强术后颈椎的稳定性,有效地减少植骨块脱出、终板骨折塌陷以及迟发的颈椎后凸畸形的产生,促进病变部位植骨融合,并允许患者在最少外固定或无外固定时能够早期活动。本文对颈椎前路钢板的发展过程、生物力学特点、临床应用进行综述。     

Development of adjacent-level ossification in patients with an anterior cervical plate

BACKGROUND: It has been our experience that ossification occurs adjacent to anterior cervical plates. Our hypothesis was that the closer the plate is to the adjacent disc space, the greater the ossification. METHODS: We retrospectively reviewed the lateral radiographs of the cervical spine of 118 patients who had a solid fusion following an anterior cervical arthrodesis with a plate for the treatment of a degenerative cervical condition; none of the patients had had cervical spine surgery prior to the index arthrodesis. The plate-to-disc distance was measured on the postoperative lateral radiograph and was used to divide the patients into two groups for each of the two adjacent disc spaces. In group A the plate-to-disc distance was <5 mm, and in group B it was >/=5 mm. The mean duration of follow-up was 25.7 months. The severity of the ossification at the two adjacent disc spaces was classified on a scale ranging from grade 0 (no ossification) to grade 3 (complete bridging). Eighteen patients were excluded from the measurement of the severity of the caudal ossification because overlapping by the bone of the shoulder precluded adequate visualization of the caudal level. RESULTS: Ossification developed in seventy (59%) of the 118 cephalad adjacent disc spaces and twenty-nine (29%) of the 100 caudal adjacent disc spaces (p < 0.001). The mean cephalad plate-to-disc distance was shorter than the mean caudal plate-to-disc distance (p < 0.001). The rate of ossification was higher in group A than in group B, both at the cephalad adjacent disc spaces (67% compared with 24%) and at the caudal adjacent disc spaces (45% compared with 5%) (both p < 0.001). In addition, 93% (twenty-six) of the twenty-eight cases of moderate-to-severe ossification developed in group A. CONCLUSIONS: We found a positive association between adjacent-level ossification following anterior cervical plate procedures and the plate-to-disc distance. We now strive to place anterior cervical plates at least 5 mm away from the adjacent disc spaces in order to decrease the likelihood of moderate-to-severe adjacent-level ossification.     

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。     

前路带锁钢板治疗严重颈椎损伤

目的 :评价AO颈椎前路带锁钢板 (cervicalspinelockingplate ,CSLP)在严重颈椎损伤中的应用效果。 方法 :对 10例颈椎骨折脱位伴截瘫或不全截瘫患者行颈椎前路减压、植骨融合 ,并采用CSLP内固定。结果 :经平均 18个月随访 ,全组病例植骨融合良好 ,未发现钢板螺钉松动、断裂等并发症。结论 :CSLP具有高度的内在稳定性 ,操作简单、安全、并发症少 ,内固定材料生物相容性好、无磁性 ,适用于颈椎骨折、脱位的治疗。     

Osteosynthesis of the lower cervical spine using an anterior paediculo-isthmic screwed plate

The authors report a new arthrodesis of the inferior cervical spine using a plate screwed into the pedicles by an anterior route. The procedure allows a complete and immediate stabilization of the cervical spine. Cervical orthosis is unnecessary in postoperative course.     

Biomechanical comparison of anterior cervical plating and combined anterior/lateral mass plating.

BACKGROUND CONTEXT: Previous studies showed anterior plates of older design to be inadequate for stabilizing the cervical spine in all loading directions. No studies have investigated enhancement in stability obtained by combining anterior and posterior plates. PURPOSE: To determine which modes of loading are stabilized by anterior plating after a cervical burst fracture and to determine whether adding posterior plating further significantly stabilizes the construct. STUDY DESIGN/SETTING: A repeated-measures in vitro biomechanical flexibility experiment was performed to investigate how surgical destabilization and subsequent addition of hardware components alter spinal stability. PATIENT SAMPLE: Six human cadaveric specimens were studied. OUTCOME MEASURES: Angular range of motion (ROM) and neutral zone (NZ) were quantified during flexion, extension, lateral bending, and axial rotation. METHODS: Nonconstraining, nondestructive torques were applied while recording three-dimensional motion optoelectronically. Specimens were tested intact, destabilized by simulated burst fracture with posterior distraction, plated anteriorly with a unicortical locking system, and plated with a combined anterior/posterior construct. RESULTS: The anterior plate significantly (p<.05) reduced the ROM relative to normal in all modes of loading and significantly reduced the NZ in flexion and extension. Addition of the posterior plates further significantly reduced the ROM in all modes of loading and reduced the NZ in lateral bending. CONCLUSIONS: Anterior plating systems are capable of substantially stabilizing the cervical spine in all modes of loading after a burst fracture. The combined approach adds significant stability over anterior plating alone in treating this injury but may be unnecessary clinically. Further study is needed to assess the added clinical benefits of the combined approach and associated risks.     

颈椎人工椎间盘置换术与颈椎前路减压融合术治疗双节段颈椎病的Meta分析

目的:系统评价前路颈椎人工椎间盘置换术(anterior cervical artificial disc replacement,ACDR)与前路颈椎减压融合术(anterior cervical decompression and fusion,ACDF)治疗双节段颈椎病的有效性与安全性。方法:计算机检索2016年5月1日以前Pub Med、Embase、Medline、Cochrane图书馆、中国生物医学文献数据库(CBM)、中国期刊全文数据库(CNKI)、万方数据库(Wanfang Database)、维普中文科技期刊数据库(VIP)关于应用ACDR与ACDF治疗双节段颈椎病的随机对照试验(randomized control Ied trials,RCT)及队列研究(cohort study)的文献,纳入文献的方法学质量采用改良Jadad量表及MINORS量表评价,提取各研究中术后24个月、48个月、60个月时的颈部功能障碍指数(NDI)评分、颈痛VAS评分、上肢痛VAS评分、SF-36评分、神经功能改善率、邻近节段椎间盘退变、再手术率、不良事件、患者满意度数据,并将这些研究的数据通过Review Manager 5.3软件进行Meta分析。结果:共纳入9篇文献、2570例患者,随访时间24~60个月,ACDR组1601例,ACDF组969例。纳入文献改良Jadad评4分3篇,3分4篇;MINORS评分18分2篇。Meta分析结果显示:术后24个月、48个月、60个月随访时,ACDR组的NDI[SMD=0.52;95%CI:(0.43,0.62),P0.00001]、颈痛VAS[SMD=0.19;95%CI:(0.10,0.29),P0.0001]、上肢痛VAS[SMD=0.15;95%CI:(0.06,0.25),P=0.002]、SF-36生理健康评分(PCS)[SMD=0.35;95%CI:(0.25,0.44),P0.00001]改善均优于ACDF组;神经功能改善率[RR=1.01;95%CI:(0.97,1.05),P=0.54]两组比较无统计学差异;两组上位椎间盘退变[RR=0.43;95%CI:(0.37,0.51),P0.00001]、下位椎间盘退变[RR=0.35;95%CI:(0.19,0.66),P=0.001]、再手术率[RR=0.30;95%CI:(0.23,0.40),P0.00001]、不良事件发生率[RR=0.72;95%CI:(0.58,0.89),P=0.003]、满意度[RR=1.08;95%CI:(1.04,1.11),P0.0001]比较差异均有统计学意义,ACDR组均优于ACDF组。结论:ACDR和ACDF治疗双节段颈椎病在改善神经功能方面一致,但在提高患者术后生活质量、减少手术相关并发症方面,前者优于后者。     

3种颈椎前路减压重建方式对稳定性影响的生物力学研究

[目的]研究颈椎前路不同减压、植骨固定方式对生物力学稳定性的影响。[方法]18具新鲜人尸体颈椎标本,随机分为三组,分别采用前路3节段椎间盘切除植骨融合固定(ACDF)、分节段混合减压植骨融合固定(ACHDF)及椎体次全切除植骨融合固定(ACCF),采用脊柱三维运动试验机依次测定正常状态、减压后、植骨后、钢板固定后的三维活动度,计算出中性区(NZ)、运动范围(ROM),并进一步计算出其稳定潜能指数(SPI);所得数据进行统计学处理,比较各组间差异。[结果]正常状态下,三组标本所测得的ROM、NZ统计学处理差异无显著性。三种不同方式减压后,SPIROM三组间无差异,但ACCF组三种状态下SPINZ和ACDF组相比,差异具有显著性;骨块植入后,ACCF组屈伸运动时的SPINZ和另外两组相比,差异有显著性(P<0.05),三组间不同状态下SPIROM比较,差异不具有显著性(P>0.05);钢板固定后,ACCF组屈伸运动时的SPIROM和ACDF及ACHDF组相比,差异具有显著性P<0.05)。[结论]3节段病变三种减压、植骨、固定方式术后均可恢复即刻稳定性,ACDF和ACHDF在恢复稳定性方面优于ACCF。     

钛网并前路钢板在颈前路手术中的应用

目的探讨钛质外科网及带锁钢板在颈椎病损手术治疗中的应用价值。方法对48例颈前路减压术临床资料进行回顾性研究,按JOA评分评定手术效果,颈椎正侧位及屈伸位X线检查判断融合效果。结果JOA评分从术前11.08分±1.68分提高到术后13.56分±1.65分,无一例患者症状加重;按照上海长征医院CSM标准评定,优良率达87.5%。椎体间隙高度得以恢复,植入物无移位脱落,钛钢板及螺钉无移位及松动,植骨融合良好。结论钛质外科网包容自体椎体骨颗粒行植骨融合结合前路钢板固定术可代替自体髂骨融合术,治疗效果肯定,可缩短手术时间,避免取髂骨所致并发症。