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     

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。     

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。     

颈椎间盘置换术与颈前路椎间融合术治疗双节段颈椎间盘退变性疾病疗效的Meta分析

目的 :系统评价颈椎间盘置换术(TDR)与颈前路椎间盘切除椎间植骨融合术(ACDF)治疗相邻两个节段颈椎间盘退变性疾病的疗效。方法:检索Pubmed、Medline、Embase等数据库,筛选应用两种手术方式治疗相邻两个节段颈椎间盘退变性疾病的前瞻性临床对照研究;各研究中观察组术式为TDR(TDR组),对照组术式为ACDF(ACDF组);两组病例数均不少于10例;随访时间均不少于2年;术后疗效评价指标至少包括以下指标中的一项:颈痛及上肢痛VAS评分(VAS),颈部功能障碍指数(NDI),健康调查简表SF-36评分(SF-36),术后不良事件(AE)等指标。采用Doowns-Black评分及NOS评分评价纳入研究的质量。结果:共纳入5篇英文文献,2篇为随机对照研究(RCT),3篇为前瞻性队列研究,研究质量Doowns-Black评分均在18分及以上,NOS评价前瞻性队列研究质量均为6星。共纳入593例患者,其中TDR组314例,ACDF组279例。经Meta分析合并效应指标,末次随访时颈痛VAS评分标准化均数差(SMD)及不良事件发生相对危险度(RR)两组比较无显著性差异(P0.05);TDR组上肢痛VAS评分、NDI评分、邻近上节段和下节段屈伸ROM、邻近节段退变低于ACDF组(P0.05),SF36-PCS躯体健康评分及手术节段屈伸ROM SMD高于ACDF组(P0.05)。结论 :相邻两个节段颈椎间盘退变性疾病行TDR的疗效较ACDF具有优势,安全性较高,但需要更多大样本随机对照研究以及更长时间的随访结果来验证。     

Efficacy of multilevel anterior cervical discectomy and fusion versus corpectomy and fusion for multilevel cervical spondylotic myelopathy: a minimum 5-year follow-up study

Purpose

We evaluated radiologic and clinical outcomes to compare the efficacy of anterior cervical discectomy and fusion (ACDF) and anterior corpectomy and fusion (ACCF) for multilevel cervical spondylotic myelopathy (CSM).

Methods

A total of 40 patients who underwent ACDF or ACCF for multilevel CSM were divided into two groups. Group A (n = 25) underwent ACDF and group B (n = 15) ACCF. Clinical outcomes (JOA and VAS scores), perioperative parameters (length of hospital stay, blood loss, operation time), radiological parameters (fusion rate, segmental height, cervical lordosis), and complications were compared.

Results

Both group A and group B demonstrated significant increases in JOA scores and significant decreases in VAS. Patients who underwent ACDF experienced significantly shorter hospital stays (p = 0.031), less blood loss (p = 0.001), and shorter operation times (p = 0.024). Both groups showed significant increases in postoperative cervical lordosis and achieved satisfactory fusion rates (88.0 and 93.3 %, respectively). There were no significant differences in the incidence of complications among the groups.

Conclusions

Both ACDF and ACCF provide satisfactory clinical outcomes and fusion rates for multilevel CSM. However, multilevel ACDF is associated with better radiologic parameters, shorter hospital stays, less blood loss, and shorter operative times.     

磷酸钙骨水泥加固颈椎前路单皮质骨螺钉的生物力学研究

[目的]评价磷酸钙骨水泥（calcium phosphate cement，CPC）对颈椎前路单皮质骨螺钉固定的加固作用。[方法]单皮质骨螺钉固定于C3-6椎体标本，行轴向拔出实验，周期抗屈实验，抗剪切力测试。[结果]修复组、强化组螺钉的最大轴向拔出力（POS）明显高于对照组，强化组周期抗屈后位移明显小于对照组，而最大抗剪切力明显大于对照组。[结论]磷酸钙骨水泥能显著提高螺钉的最大轴向拔出力及抗剪切能力，对颈椎前路螺钉的固定有明显的加强作用。     

下颈椎前路椎弓根螺钉内固定在三柱损伤模型中初始稳定性的生物力学研究

目的:比较下颈椎前路椎弓根螺钉内固定(ATPS)和3种传统颈椎内固定技术在下颈椎3柱损伤模型中的初始稳定性,为其临床应用提供力学依据。方法:采集6具人颈椎标本并测定各原始标本(原始标本组)的三维运动范围,制成三柱损伤模型,模拟钛网植骨后依次行ATPS、前路钢板固定(AP)、前路钢板+侧块螺钉固定(AP+LMS)、后路椎弓根螺钉内固定(PTPS),测量4种内固定技术下的三维运动范围,将结果标准化并进行相互比较。结果:ATPS组屈伸、侧弯、轴向旋转运动范围标准化数值分别为(77.17±4.75)%、(82.00±2.61)%、(83.17±2.23)%,均明显小于原始标本组的100%、100%、100%(P0.05)。AP组屈伸、侧弯、轴向旋转运动范围标准化数值分别为(119.67±7.42)%、(116.33±7.53)%、(112.67±5.99)%,均明显大于原始标本组(P0.05)。AP组屈伸、侧弯、轴向旋转运动范围标准化数值均明显大于ATPS组(P0.05)。PTPS组屈伸、侧弯运动范围标准化数值与ATPS组相比差异均无统计学意义(P0.05);其轴向旋转运动范围标准化数值为(86.83±2.48)%,明显大于ATPS组(P=0.009)。AP+LMS组屈伸运动范围标准化数值为(68.50±2.43)%,小于ATPS组(P=0.003);其侧弯、轴向旋转运动范围标准化数值与ATPS组相比差异均无统计学意义(P0.05)。结论:ATPS可在下颈椎三柱损伤模型中提供足够的初始稳定性,其在生物力学性能方面优于AP、PTPS,和AP+LMS相近,适用于无需后路切开减压复位的下颈椎三柱损伤病例。     

Outcomes of three anterior decompression and fusion techniques in the treatment of three-level cervical spondylosis

The purpose of this article is to compare the outcomes of three different anterior approaches for three-level cervical spondylosis. The records of 120 patients who underwent anterior approaches because of three-level cervical spondylosis between 2006 and 2008 were reviewed. Based on the type of surgery, the patients were divided into three groups: Group 1 was three-level anterior cervical discectomy and fusion (ACDF); Group 2 anterior cervical hybrid decompression and fusion (ACHDF, combination of ACDF and ACCF); and Group 3 two-level anterior cervical corpectomy and fusion (ACCF). The clinical outcomes including blood loss, operation time, complications, Japanese Orthopedic Association (JOA) scores, C2–C7 angle, segmental angle, and fusion rate were compared. There were no significant differences in JOA improvement and fusion rate among three groups. However, in terms of segmental angle and C2–C7 angle improvement, Group 2 was superior to Group 3 and inferior to Group 1 (all P < 0.01). Group 2 was less in operation time than Group 3 (P < 0.01) and more than Group 1 (P < 0.01). Group 3 had more blood loss than Group 1 and Group 2 (all P < 0.01) and had higher complication rate than Group 1 (P < 0.05). No significant differences in blood loss and complication rate were observed between Group 1 and Group 2 (P > 0.05). ACDF was superior in most outcomes to ACCF and ACHDF. If the compressive pathology could be resolved by discectomy, ACDF should be the treatment of choice. ACHDF was an ideal alternative procedure to ACDF if retro-vertebral pathology existed. ACCF was the last choice considered.     

Mobility provocation radiostereometry in anterior cervical spine fusions

This study aimed to evaluate the use of mobility-provocation radiostereometry (RSA) in anterior cervical spine fusions and compare the results to deformation studies on the same patients and plain flexion-extension radiographs. Mobility-provocation RSA was used to evaluate anterior cervical spine fusions in 45 patients. The motions recorded at 3 and 12 months postoperatively were compared to RSA measurements of deformation of the fusion over time and to plain flexion-extension radiographs in the same patients taken 3 months postoperatively. Studies of rotations from right to left revealed ten cases with significant motion at 3 months, and three at 12 months. With motion from flexion to extension, ten cases showed significant motion at 3 months and three at 12 months. In only three cases was the mobility-provocation RSA considered to add any information on the stability of the fusions compared to that obtained with the deformation studies. In 37 patients mobility-provocation radiography in flexion-extension using conventional technique was done to evaluate the accuracy. The mean difference between angular motions recorded on plain radiographs and rotations around the transverse axis in flexion to extension recorded with RSA was 1.6° (range 0.04°–8.04°, SD 2.1°). The corresponding 95% and 99% confidence limits for the difference between the two methods were 5.8° and 7.2°. The study showed that the use of mobility-provocation RSA did not add any information over that obtained by deformation RSA studies. Conventional radiography is too inaccurate to measure inducible displacement in this patient population.     

单间隙颈椎前路减压单纯植骨融合与加用钢板的疗效比较

目的：对单间隙颈椎前路减压后有无必要在单纯植骨基础上加用钢板内固定作一初步探讨。方法：对48例单间隙病变行前路减压手术的患者随访1－4年,平均2．2年。根据症状改善情况及影像学资料对单纯植骨和加用前路钢板内固定作分析比较。结果：根据JOA评分,单纯植骨组和加用钢板内固定组之间在疗效的改善方面近似,都能获得满意的融合率;在椎间高度的恢复和维持方面加用前路钢板有明显效果（P＜0．05）,在恢复和维持颈椎生理曲度方面,加用钢板也优于单纯植骨。结论：使用前路钢板安全、可靠,在单间隙病变手术中加用前路钢板有助于恢复和保持颈椎生理曲度,防止植骨块的塌陷,可能利于长期手术疗效的保持。     

Microscope-assisted anterior cervicaldecompression and plating techniques for multilevel cervical spondylosis

The use of the operating microscope during anterior cervical decompressions can markedly improve visualization forthe surgeon as well as the assistants. The enhanced visualization can result in safer, faster, and more complete decompressions. After decompression and grafting, numerous cervical plating systems are available. These can provide immediate stability to the reconstruction, decreasing the risk of graft extrusions. Meticulous care must be exercised in sizing and applying the plate to avoid complications. The long-term outcome of arthrodeses augmented by plates and the true incidence of complications associated with cervical plates are unknown.     

应用颈椎前路动态ABC钢板促进颈椎椎体间融合

目的观察颈椎前路动态ABC钢板促进颈椎椎体间植骨融合的疗效。方法对40例患者（68个节段）行颈椎前路椎间盘摘除、椎体间自体髂骨植骨、ABC钢板内固定术。术后观察ADL评分，颈椎曲度、椎体间融合及融合植骨块下沉情况。结果40例均获随访，时间12—44（22．17±8．33）个月。ADL评分术前2～13（7．92±3．07）分，术后8—17（13．94±2．48）分，改善明显。术后无钢板、螺钉断裂或松动现象发生。39例颈椎生理性前凸获得良好改善，仅1例术后3个月融合椎体邻近节段发生反曲，患者颈部无不适症状。68个融合节段中，67个节段6个月内融合，1个节段延迟至术后12个月时方融合。术后3个月内，单节段融合植骨块下沉平均（1．21±0．54）mm，2节段平均（2．01±0．87）mm，3节段平均（2．97±0．82）mm。3个月后各节段下沉不再明显。结论应用动态ABC钢板可以降低植骨后相关并发症的发生，有效避免静态钢板造成的应力遮挡，从而促进颈椎椎体间的融合。     

颈椎前路减压人工颈椎间盘置换术与融合术治疗单节段颈椎间盘突出症的短期疗效比较

背景：颈前路椎间盘切除植骨融合术（ACDF）能够为有症状的颈椎病患者提供较好的治疗效果,但颈椎融合可导致相邻节段椎间盘内部应力增加,加速邻近节段椎间盘的退变。颈椎人工椎间盘置换术（ACDR）作为最具代表性的颈椎前路非融合技术,为颈椎间盘突出症的治疗提供了另外一种外科手段。目的：比较ACDR和ACDF治疗单节段颈椎间盘突出症的临床效果。方法：2009年1月至2012年2月,61例单节段颈椎间盘突出症患者接受Discover人工颈椎间盘置换手术（置换组,26例）或ACDF手术（融合组,35例）。分别在术前,术后1周,术后3、6、12及24个月对患者进行疼痛视觉模拟评分（VAS）、日本矫形外科协会（JOA）评分及影像学评估,同时记录患者并发症及二次手术情况。结果：最终,52例患者（融合组29例,置换组23例）获得平均15.3个月（12-24个月）随访。两组患者术后各随访时间点的颈痛、上肢痛VAS和JOA评分,较术前均有改善（P〈0.05）,但两组间无显著统计学差异（P〉0.05）。置换组术后手术节段及邻近节段屈伸活动度与术前比较无统计学差异（P〉0.05）。融合组融合成功率为90.5%。置换组中2例患者术后6个月时假体有〈3 mm的前移,l例术后发生脑脊液漏。融合组中1例患者发生邻椎病并接受二次手术治疗。结论：单节段Discover人工颈椎间盘置换术和ACDF均可明显缓解颈椎间盘突出症患者的症状。间盘置换还能减少手术邻近节段代偿活动度的增加,有望预防相邻节段退变的发生。     

ACCF联合颈前路减压zero-p椎间植骨融合内固定术治疗多节段脊髓型颈椎病

目的探讨颈前路椎体次全切除减压融合术(ACCF)联合颈前路减压zero-p椎间植骨融合内固定术治疗多节段脊髓型颈椎病的临床疗效。方法回顾性分析自2016-05—2017-07采用ACCF联合颈前路减压zero-p椎间植骨融合内固定术治疗的30例多节段脊髓型颈椎病,比较术前、术后1周及末次随访时JOA评分、颈椎Cobb角、椎间隙高度。结果30例均顺利完成手术并获得完整随访,随访时间平均21.6个月,切口均一期愈合,植骨均骨性愈合,无内固定松动、移位、断裂、伤口感染、声音嘶哑及神经功能加重等并发症。术后1例出现脑脊液漏,2例出现吞咽不适,非手术治疗后均治愈。术后1周与末次随访时JOA评分、颈椎Cobb角、椎间隙高度较术前均明显改善,差异有统计学意义(P<0.05)。末次随访时根据JOA评分改善率评定综合疗效:优12例,良14例,可4例。结论ACCF联合颈前路减压zerop椎间植骨融合内固定术治疗多节段脊髓型颈椎病安全可靠,能够有效地恢复椎间隙高度和颈椎生理曲度。     

颈椎病颈前入路显微手术225例分析

目的总结颈前入路显微手术治疗颈椎病的临床经验。方法借助手术显微镜和高速磨钻对225例颈椎病患者进行颈前入路显微减压手术，采用自体骨、钛网或Cage融合后使用钉板系统固定；术中用体感诱发电位（SEP）进行监护。结果本组术后均无重大并发症发生。随访5～120个月，影像学资料证实受累脊髓、神经根减压彻底，自体骨、钛网或Cage融合良好，无移动、塌陷或滑脱，钛板内固定位置准确，无螺钉松脱或钛板断裂。各组的JOA评分较术前提高。结论颈前入路显微手术治疗颈椎病，手术创伤小，术后恢复快，手术成功率高。     

两种颈前路减压融合术治疗两节段脊髓型颈椎病的疗效分析

目的:探讨颈前路椎间盘切除融合术(anterior cervical discectomy with fusion,ACDF)与颈前路椎体次全切减压融合术(anterior cervical corpectomy with fusion,ACCF)治疗相邻两节段脊髓型颈椎病的临床疗效。方法:对2016年1月至2017年12月收治的相邻两节段脊髓型颈椎病37例患者的临床资料进行回顾性分析,男15例,女22例,年龄43～69岁,平均54.6岁。根据手术方法的不同分为ACDF治疗组(A组,17例)和ACCF治疗组(B组,20例)。记录两组患者的手术时间、术中出血量,比较两组患者术前及术后1、12个月颈椎融合节段Cobb角、颈椎曲度,采用日本矫形外科协会(Japanese Orthopaedic Association,JOA)评分评价临床疗效,并观察两组术后并发症情况。结果:所有患者获得随访,时间12～24个月,平均18.5个月。手术时间、术中出血量A组分别为(106.3±22.6) min、(52.2±26.4) ml,B组分别为(115.6±16.8) min、(61.7±20.7) m...     

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。     

Adjacent segment disease after anterior cervical interbody fusion

BACKGROUND CONTEXT: There have been many follow-up studies on anterior interbody fusion for cervical nerve root and spinal cord compression, and excellent neurological outcomes have been reported. However, postoperative degenerative changes at adjacent discs may lead to the development of new radiculopathy or myelopathy. In the previous reports, the incidence of symptomatic adjacent segment disease has ranged from 7% to 15%. PURPOSE: The present study was undertaken to investigate the incidence of symptomatic adjacent segment disease after anterior cervical interbody fusion (ACIF) and to identify the factors that are related to the development of this disease. STUDY DESIGN/SETTING: This is a retrospective cohort study. PATIENT SAMPLE: A total of 112 patients were followed up clinically and radiologically for more than 2 years. OUTCOME MEASURES: Follow-up evaluation was primarily by means of clinical visits. The postoperative course of any symptoms, the findings of neurological examination and serial follow-up radiographs were performed in all patients. METHODS: The diagnosis of symptomatic adjacent segment disease was based on the presence of new radiculopathy or myelopathy symptoms referable to an adjacent level, and the presence of a compressive lesion at an adjacent level by magnetic resonance imaging or myelography. We evaluated the correlation between the incidence of symptomatic adjacent segment disease and the following clinical parameters (age at operation, sex, number of the levels fused) and radiological parameters (preoperative cervical spine alignment, preoperative range of motion of C2-C7 cervical spine, anteroposterior spinal canal diameter, preoperative existence of an adjacent segment degeneration on plain radiograph, myelography and magnetic resonance imaging [MRI]). RESULTS: Symptomatic adjacent segment disease developed in 19 of 112 patients (19%) followed. A Kaplan-Meier survival analysis was performed in order to follow the disease-free survival of the entire series of patients. The disease-free survival rates were 89% at 5 years, 84% at 10 years and 67% at 17 years. The incidences of indentation of dura matter on preoperative myelography or disc protrusion on MRI at the adjacent level were significantly higher in disease cases (p=.0087, .0299, respectively; chi-squared test). However, the other parameters did not show a statistically significant difference. There were seven cases (37%) who had failure of nonoperative treatment and additional operations were performed. CONCLUSIONS: The incidence of symptomatic adjacent segment disease after ACIF was higher when preoperative myelography or MRI revealed asymptomatic disc degeneration at that level regardless of the number of the levels fused, preoperative alignment, spinal canal diameter or fusion alignment.     

A prospective randomized study comparing a cervical carbon fiber cage to the Smith–Robinson technique with allograft and plating: up to 24 months follow-up

Introduction: Intervertebral carbon fiber cages may reduce graft collapse and promote bony fusion. Their safety and efficacy in the cervical spine have been investigated; however, no study has compared the outcomes of anterior cervical decompression and placement of a carbon fiber cage with placement of allograft and plate. Methods: Forty consecutive patients who met inclusion criteria were enrolled and randomized to anterior cervical discectomy with carbon fiber cage alone (n=20) or with allograft with plating (n=20). Clinical and radiographic evaluations were performed at baseline and at 6 weeks, 3, 6, 12 and 24 months. Neck and arm pain as well as neck disability index (NDI) were assessed at every visit. The Short Form (SF)-36 was completed prior to operation and at 12-month intervals. Cervical radiographs were evaluated pre-op and at every follow-up for evidence of fusion and instability. Results: No significant difference was found between the two randomized groups with respect to pre-operative age (mean 50 years), sex, employment status, duration of pain or cervical levels affected. The mean follow-up period was 14 months (range, 6–26 months). The clinical pain and disability improvements were similar for both treatments. Post-operative donor site pain was only present in the cage group, but not of significant long-term disability. At up to 24 months, NDI scores were significantly improved in both groups when compared with baseline. At 12 and 24 months, all SF-36 questionnaire responses were also improved in both the treatment groups. However, there was no statistically significant difference in outcomes between the two groups at any time. The fusion rate was 100% in both groups by 12 and 24 months, without evidence of instability. There were no differences in complications between both groups. Conclusions: The outcomes after cervical decompression and placement of a carbon fiber cage appear to be similar to cervical decompression with allograft and plating by the Smith–Robinson technique.