颈椎前路一体化钢板椎间融合器置入后与颈椎生物力学环境的匹配

背景：研究表明,颈椎一体化前路钢板融合器比现行钢板和融合器具有更多理论上的优势。但是目前有关其生物力学方面的研究国内尚无文献报道。 目的：观察与评价颈椎前路一体化钢板椎间融合器内固定置入后的生物力学特征。 方法：采集6具成人尸体颈椎标本,分为5组进行测试,即正常组、椎间盘摘除组、颈椎前路一体化钢板椎间融合器固定组、CBK融合器固定组及CBK融合器+Secuplate钢板联合固定组,以C5~6椎间隙为观察对象,进行生物力学实验。 结果与结论：颈椎间盘摘除后,颈椎在各个方向运动加大,刚度及强度等生物力学数值减小,脊柱失稳。与椎间盘摘除组相比,颈椎前路一体化钢板椎间融合器固定后其强度增加24%,椎体应变减小31%,刚度增加14.3%,位移减小15%(P < 0.05),颈椎前路一体化钢板椎间融合器对颈椎的力学性能影响较小,说明它能较好地与颈椎的力学环境相匹配。CBK融合器固定后抗后伸及旋转作用相对较小,同椎间盘摘除组相比差异有显著性意义(P < 0.05)。CBK融合器+Secuplate钢板联合固定组载荷强度和应变过大,与椎间盘摘除组相比其强度增加27%,椎体应变减小38%,刚度增加17%,位移减小17% (P < 0.05),颈椎刚度增大且邻近椎节的运动有增大趋势,将引起力学性能的改变。提示颈椎前路一体化钢板椎间融合器结合了颈椎前路钢板和融合器生物力学方面的优点,能较好地与颈椎的力学环境相匹配。     

前屈后伸载荷下颈椎间孔的孔径变化：Bryan颈人工椎间盘置换与颈椎钢板植骨内固定的比较

背景：诸多针对脊椎椎体间固定融合后相邻节段应力变化的生物力学测试结果并不尽相同,载荷控制与位移控制试验模式下所反映出的相邻节段应力状况其结果也相差甚远。 目的：分析椎间盘完整、椎间盘切除、Bryan颈人工椎间盘置换和前路颈椎植骨融合钢板内固定后,成人尸体颈椎标本分别在前屈后伸载荷下C5/6椎间孔孔径和面积的变化情况。 方法：分别测量C5/6椎间盘完整、椎间盘髓核摘除、Bryan颈人工椎间盘置换和前路钢板植骨内固定4种状态下以0.25,0.50,0.75,1.00,1.25,1.50 N•m的分级载荷加载于标本的前屈后伸状态时C5/6椎间孔孔径和面积的变化情况。 结果与结论：前屈后伸各级加载时,C5/6椎间孔上下径、上前后径、下前后径和面积椎间盘完整组、Bryan颈人工置换组和钢板植骨内固定组高于椎间盘髓核摘除组,差异有显著性意义(P < 0.05),Bryan颈人工置换组高于钢板植骨内固定组,差异有显著性意义(P < 0.05),可见颈椎间盘髓核摘除后C5/6椎间孔有效空间明显减少。     

颈前路钢板置入内固定加椎间植骨治疗Ⅱ型Hangman骨折的生物力学评价

背景：C2/3椎间盘切除，钢板置入内固定加椎间植骨是治疗Hangman骨折的常用术式。该术式在临床应用广泛，但目前尚缺乏相关实验评价钢板置入内固定治疗Hangman骨折的生物力学特点研究。 目的：评价钢板置入内固定+椎间植骨治疗Ⅱ型Hangman骨折的生物力学稳定性。 方法：6具正常成人新鲜冷冻颈椎，每一标本依次制作成以下3种状态组：即正常对照组、Ⅱ型Hangman骨折模型组、椎间植骨+钢板内固定组。按以上顺序应用脊柱三维运动试验机和三维激光扫描仪测试每一状态C2/3节段的三维运动范围。 结果与结论：与正常对照组比较，Ⅱ型Hangman骨折模型组C2/3节段前屈、后伸、旋转及侧弯关节活动度均显著增大(P < 0.05)，钢板内固定+椎间植骨组旋转方向关节活动度显著增大(P < 0.05)；与Ⅱ型Hangman骨折模型组相比，钢板内固定+椎间植骨组C2/3节段前屈、后伸及侧弯关节活动度均显著减小(P < 0.05)。结果提示钢板置入内固定能够在前屈、后伸及侧弯方向恢复Ⅱ型Hangman骨折的稳定性，然而在旋转方向缺乏稳定作用，术后需辅以外固定以确保融合。     

颈椎动态稳定器置入非融合颈椎的生物力学分析

背景：颈椎动态稳定器的解剖型设计与正常椎间盘应具有相似的生物力学特点,其动态性设计具有轴向顺应性以及震荡吸收功能,而前缘倒齿嵌入上下椎体可获得足够的轴向稳定性。 目的：比较颈椎前路融合内固定和颈椎动态稳定器置入非融合后颈椎相关生物力学指标变化。 方法：将6具新鲜人C2~C7颈段脊柱标本随机分为3组,在完整颈椎测试后分别行C5、6前路减压颈椎动态稳定器DCI置入,C5、6前路减压单纯Cage融合内固定,C5、6前路减压颈椎前路一体化钢板椎间融合器融合内固定。检测各组标本前屈、后伸、左右侧屈不同生理运动工况并施加2.0 N•m纯力偶矩,颈椎标本C5~6上下邻近节段手术前后活动度大小。 结果与结论：3种内固定后C5~6上下邻近节段较正常颈椎标本前屈、后伸和左右侧屈关节活动度值均有所增加,且表现出良好的即时稳定性,但颈椎动态稳定器置入组最接近正常值;3组间C5~6上下邻近节段关节活动度差异无显著性意义。表明颈椎动态稳定器置入后对邻近节段椎体活动度无明显影响或影响甚小,在一定程度上减小假体与其邻近椎体轴向应力,有效地维持颈椎活动。     

经皮穿刺斜入路置入单枚膨胀式腰椎间融合器的生物力学试验

背景：各种椎间融合器(cage)已相继被用于腰椎椎间融合,其力学性能良好,临床效果满意。常规的后路融合要平行置入双枚cage,但有学者提出可以斜向置入单枚cage的方法。 目的：实验设计方案特点在于将膨胀式cage和斜向置入单枚cage的方法相结合,通过人体外的生物力学试验,以得到一种在临床上能满足治疗要求而创伤更小的方法。 设计、时间及地点：随机抽样对照实验,于2005-05/2008-05在上海生物力学工程研究所完成。 材料：可膨胀式椎间融合器采用仿制的以色列Disc-O-Tech公司生产的B-Twin Cage。小牛新鲜腰椎标本自购自备。 方法：用18具小牛腰椎运动功能单位进行生物力学试验,分为3组,对照组、单枚斜向组及双枚平行组各6个。先测试对照组完整标本力学性能而后分组置入进行力学试验。采用WE-10A液压万能试验机,对标本进行轴向中心压缩、前屈、后伸、左右侧屈以及扭转刚度试验。 主要观察指标：各组标本的轴向刚度及扭转刚度结果。 结果：双枚cage置入组比单枚cage置入组的轴向刚度高,但只有轴向中心压缩和后伸运动方向的差异有显著性意义(P < 0.05),扭转刚度单枚cage置入组较双枚cage置入组高(P < 0.05)。 结论：经皮穿刺斜入路放置单枚膨胀式椎间融合器进行椎间骨融合从理论上是可行的;置入膨胀式融合器的腰椎功能单元的生物力学稳定性能增强,其楔形形状有一定作用;与经侧后路斜向置入单枚cage相比,经后路平行置入双枚cage的轴向稳定性高,但扭转稳定性低。     

纳米羟基磷灰石增强聚酰胺66颈椎仿生骨块材料生物力学分析

背景：颈椎前路次全椎体减压后形成的椎体骨骼缺损,需要相关的脊柱支撑物。临床上有自体髂骨和钛合金椎间融合器应用,但均有相关的并发症和不适现象。 目的：自行研发的生物型颈椎仿生骨块在尸体标本上进行相关的生物力学分析,验证其生物学强度和稳定性。 设计、时间及地点：对比观察实验,于2008-09/10在上海大学生物力学实验室完成。 材料：南京航空航天大学材料科学与技术学院制备的纳米羟基磷灰石增强聚酰胺66颈椎仿生骨块,尺寸为1.2 cm×1.4 cm×2 cm的中空柱状物,中空为直径0.5 cm（2 cm为植入物长度可以根据实际骨槽的长度进行缩短）,其内填塞在前路手术中磨碎的骨渣。 方法：16具新鲜男性冰冻尸体C1~T1部位颈椎标本及自体髂骨条,先期测量未侵入操作颈椎的生物应力作为正常组,测试后行颈椎前路次全椎体切除,一组植入自体髂骨条,钢板螺钉固定;另一组植入仿生椎体填塞骨渣,同样钢板螺钉固定。将待测标本安装在WD-5电子万能试验机上进行生物力学测量。 主要观察指标：颈椎的轴向刚度、颈椎强度、颈椎旋转能力。 结果：自体髂骨组的轴向刚度、颈椎强度、扭转力均明显低于正常组和颈椎仿生骨块植入组（P < 0.05）。颈椎仿生骨块植入组的生物力学特性与正常组比较,差异无显著性意义（P > 0.05）。 结论：纳米羟基磷灰石增强聚酰胺66颈椎仿生骨块强度大、刚度高、颈椎稳定性好。     

c/000PDLLA Cage的制备及植入山羊颈椎后体外生物力学评价

目的：设计制备适合于山羊颈椎前路减压融合的颈椎间融合器PDLLA Cage,探讨PDLLA Cage对山羊颈椎C3-4融合术后的即刻稳定作用。方法：首先设计制备PDLLA Cage,并进行力学检测,27只山羊颈椎标本随机分为4组,A组：正常对照组(n=27);B组：PDLLA Cage组（n=9）;C组：钛合金Cage组(n=9)：D组：自体三面皮质髂骨组(n=9)。完全切除颈3/4椎间盘后植入以上颈椎内植物,预载荷20N,采用1.0 Nm-4 Nm逐级加载纯力矩的方法进行前屈、后伸、侧屈和旋转的生物力学测定,由此计算出各组平均刚度（stiffness）及活动范围（ROM）,并行比较。结果：角位移变化各向量PDLLA Cage和钛金属Cage组的角位移变化与正常对照组比较均有显著差异(P<0.05 );除侧弯4Nm加载时PDLLA Cage组与三面皮质髂骨无显著差别（P＞0.05）外,Cage组与三面皮质髂骨组比较各向量变均有显著性差异(P<0.05 );三面皮质髂骨组与正常对照组比较,后伸和侧弯两种向量组间差别有显著差异(P＜0.05 );后伸和旋转加载,以及前屈加载1Nm时角位移变化PDLLA Cage组与钛合金Cage组差异无显著性（P＞0.05）。植入Cage后颈椎刚度显著增大,后伸和旋转加载时PDLLA Cage与钛合金Cage组间无显著差异(P>0.05 );钛合金Cage在其余各方向上的刚度均最大(P<0.05 )。PDLLA Cage比三面皮质髂骨组的刚度大 (P<0.05 )。结论： PDLLA Cage植入山羊颈椎能提供足够的初始稳定性, 具有很好的发展前景。     

下颈椎前路内固定联合后路经关节金属螺钉置入固定的生物力学稳定性

背景：对退变性颈椎管狭窄单纯采用前路椎体次全切除或椎间盘切除或单纯后路单开门椎管扩大成行均不能彻底完成脊髓减压和脊柱三柱稳定。 目的：探讨下颈椎前路固定联合后路经关节螺钉固定的生物力学稳定性。 方法：正常成人尸体颈椎标本,每具分别制作以下两种模型：①经后路C3~C7单开门和下颈椎前路C5椎体次全切除钛网支撑植骨、ORION内固定模型(对照组)。②经后路C3~C7单开门和经关节螺钉内固定及下颈椎前路C5椎体次全切除钛网内植骨、ORION内固定模型(实验组)。 结果与结论：实验组在前屈、后伸、左、右侧屈及左、右旋转移位角度均小于对照组(P < 0.001)。提示：①在生物力学实验中,下颈椎前路固定联合后路经关突节螺钉固定的生物力学性能优良,对抗前屈、后伸、左、右旋转的作用力更强,颈椎可获得更可靠的稳定性。②下颈椎前路固定联合后路经关节螺钉固定在对抗颈椎前屈运动时力学稳定性更为强大。     

生物椎间融合器与钢板内固定系统置入对邻近颈椎间盘的影响

背景：颈椎前路融合后邻近节段退变现象已引起临床重视,半弹性内固定系统可能较目前通用的坚强内固定对邻近颈椎间盘退变的影响小。 目的：通过融合节段邻近颈椎间盘压力监测,在除外撑开强度影响的前提下,比较生物椎间融合器与钢板内固定系统置入对犬施术节段邻近颈椎间盘退变的影响。 方法：选用健康杂种犬23只,按随机数字表法分为3组,其中预实验组5只,测量犬颈椎间盘压力正常参考值;生物可降解椎间融合器组9只;钢板置入内固定组9只。生物可降解椎间融合器组及钢板置入内固定组均经前路行C3~4椎间盘摘除,相应置入物置入内固定。术中测量邻近颈椎间盘C4~5压力,并计算置入前后C4~5椎间盘压力差作为撑开压力。置入后6个月处死动物,行Pearce分级及组织学观察,评价置入节段上位颈椎间盘(C2~3)退变程度。 结果与结论：生物可降解椎间融合器组与钢板置入内固定组压力差的差异无显著性意义(P > 0.05)。影像学及组织学检测结果显示,经Spearman等级相关分析,两组组内邻近颈椎间盘压力差与置入后6个月椎间盘退变Pearce分级、组织学分级均呈正相关(r = 3.13,2.78,P < 0.05)。生物可降解椎间融合器组椎间盘退变Pearce分级、组织学分级均低于钢板置入内固定组(P < 0.05)。提示过高的撑开压力易导致犬置入节段邻近颈椎间盘退变,与钢板内固定系统相比,应用生物椎间融合器置入内固定可以有效防止邻近节段的退变。     

纳米羟基磷灰石/聚酰胺66颈前路减压后前方骨缺损仿生髂骨的制备及性能

背景：在椎体和椎间盘切除以后,对于减压后前方骨缺损的修补长期以来以钛网和自身髂骨两种方式为主,但效果都不尽理想。 目的：制备纳米羟基磷灰石/聚酰胺66复合材料,对其进行表征和生物力学性能检测。 设计、时间及地点：重复性对比实验,于2008-01/12在南京航空航天大学材料科学与技术学院无机材料实验室完成。 材料：利用水热反应法制备纳米羟基磷灰石晶体,通过液相混合、冷压烧结制备出纳米羟基磷灰石/聚酰胺66仿生骨块。 方法：切除新鲜冰冻正常颈椎标本C5椎体,植入不同材料,钢板螺钉内固定,进行生物力学测试。具体分组为：正常颈椎组、纳米羟基磷灰石/聚酰胺66仿生髂骨钢板螺钉内固定组、髂骨植骨钢板螺钉内固定组。加载时模拟人体颈椎生理运动,即中心位、前屈位、后伸位和侧屈位4种生理情况。 主要观察指标：①通过X射线衍射仪对材料的物相进行表征。②红外图谱对材料的基团构成进行表征。③扫描电镜观察仿生骨的端口形貌。④正常颈椎、仿生髂骨、髂骨植骨进行生物力学检测。 结果：①X射线衍射结果表明纳米羟基磷灰石和聚酰胺66的主要衍射峰在复合材料中存在,但纳米羟基磷灰石对聚酰胺66的β晶型衍射峰起到宽化、削弱的作用。②红外图谱表明两者之间存在氢键。③扫描电镜观察,两者结合密实,界面性能优异。④通过生物力学实验,对比得出,仿生髂骨在载荷-应变变化、载荷-位移变化、应力强度方面都优于髂骨植骨,仅次于正常颈椎骨。 结论：所制备的纳米羟基磷灰石/聚酰胺66仿生骨力学性能优异,是一种理想的颈椎替代材料。 关键词：纳米羟基磷灰石/聚酰胺66;生物复合材料;生物力学性能;髂骨植骨;颈前路手术     

Stand-alone interbody cage versus anterior cervical plate for treatment of cervical disc herniation: Sequential changes in cage subsidence

Anterior cervical discectomy and fusion with an autogenous iliac bone graft is the gold standard treatment for cervical disc herniation. However, autologous bone grafts obtained from the anterior iliac crest are associated with significant donor-site morbidity and complications. To decrease bone graft-related problems, several types of interbody fusion cage have been developed and are used widely in clinical practice. We compared the clinical and radiological outcomes for two surgical procedures used to treat cervical disc herniation: the stand-alone interbody cage and autologous iliac bone grafting with an anterior plate. The clinical results did not differ between patients treated with the two procedures. The stand-alone cage was less invasive and had less donor-site morbidity. In patients treated with the bone graft and plate, the alignment of the fused segment was maintained in all but one patient, who exhibited nonunion. In contrast, in the cage-treated group, 44% of patients exhibited loss of lordotic alignment of more than 5 degrees and cage subsidence of 3 mm or more. All cage subsidence occurred within 3 months of surgery. Although the stand-alone cage was a less invasive and more effective procedure to treat cervical disc herniation, surgeons should consider the possible drawbacks of the associated subsidence.     

A preliminary study of the use of cage and plating for single-segment fusion in degenerative cervical spine disease.

Three different surgical methods were used to treat single-segment degenerative cervical spine disease, and the radiological and clinical outcomes were compared. The three groups compared were: 21 cases of anterior interbody fusion with iliac autograft (group A); 20 cases of anterior plate fixation with iliac autograft (group B); and 19 cases of carbon cage fusion and anterior plate fixation (group C). Bone union and changes in Cobb's angle and interbody space were evaluated using radiographs and clinical results by the method of Odom et al. Cobb's angle increased in group C, which was significantly better than the decrease in groups A and B. The interbody space decreased in group C, but was significantly less than the decrease in groups A and B. Carbon cage and anterior plate fixation can be used as an alternative surgical treatment modality for single-segment degenerative cervical spine and can provide early stability, maintain the interbody space and cervical lordosis, reduce operation time and minimize complications at the bone graft donor site.     

Cervical spondylotic radiculo-myelopathy in patients with athetoid-dystonic cerebral palsy: clinical evaluation and surgical treatment.

The acute onset of symptoms of severe cervical radiculo-myelopathy in four patients with athetoid-dystonic cerebral palsy is reported. Neurological and radiological examination showed that the spondylotic changes of the cervical spine were responsible for new neurological deficits leading to the patients being bedridden. Dystonic-athetoid neck movements may cause excessive axial neck rotation as well as flexion and extension movements of the spine. These repetitive exaggerated movements may result in early degenerative changes of the vertebrae which may enhance the radiculo-myelopathy. The four patients were treated with an anterior discectomy with interbody fusion. They were bedridden pre-operatively but all have since been able to walk with or without a cane. It is concluded that early anterior decompression with interbody fusion is a treatment of choice for cervical spondylotic radiculo-myelopathy in association with athetoid cerebral palsy.     

Use of the clavicle in anterior cervical discectomy/corpectomy fusion procedures: cadaveric feasibility study

Introduction Graft sources for cervical fusion procedures include synthetic materials, donor grafts, and autologous bones such as the iliac crest. Considering the data that autologous bone grafts seem to generate the best results for fusion, the next logical step is to seek alternative donor sites so as to attempt to reduce the morbidity associated with these procedures. To our knowledge, autologous clavicle has not been explored as a potential source for cervical fusion. Therefore, the following study was performed to verify the utility of this bone for these procedures. Materials and methods Seven adult cadavers were used for this study. In the supine position, a standard surgical approach and dissection to the anterior cervical spine were performed. Specimens underwent a standard discectomy or corpectomy with placement of harvested ipsilateral clavicle previously dissected. An anterior cervical plating system was next placed over these sites using standard techniques. Measurements of the harvested clavicle were made. Results The results of our morphometric analysis were as follows: An average of 5 cm of bone was easily removed from the middle one third of the clavicle. No gross injury was found to vicinal neurovascular structures. The middle one third of the clavicle offered sufficient bone for the one to two segments fused in our study with remaining bone for at least two additional segments. The mean diameter of this part of the clavicle was 1.2 cm. Conclusions Based on our cadaveric study, such a bony substitute as autologous clavicle might be a reasonable alternative to the iliac crest for use in anterior cervical fusion procedures.     

Anterior Cervical Discectomy and Fusion Using a Stand-Alone Polyetheretherketone Cage Packed with Local Autobone : Assessment of Bone Fusion and Subsidence

Objective

It remains debatable whether cervical spine fusion cages should be filled with any kind of bone or bone substitute. Cortical and subcortical bone from the anterior and posterior osteophytes of the segment could be used to fill the cage. The purposes of the present study are to evaluate the clinical outcomes and radiological outcomes including bone fusion and subsidence that occurred after anterior cervical discectomy and fusion using a stand-alone cage packed with local autobone graft.

Methods

Thirty-one patients who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage packed with local autobone graft from July 2009 to december 2011 were enrolled in this study. Bone fusion was assessed by cervical plain radiographs and computed tomographic scan. Nonunion was evaluated according to the absence of bony bridge on computed tomographic scan. Subsidence was defined as a ≥2 mm decrease of the interbody height at the final follow-up compared to that measured at the immediate postoperative period.

Results

Subsidence was observed in 7 patients (22.6%). Of 7 patients with subsidence greater 2 mm, nonunion was developed in 3. Three patients with subsidence greater 2 mm were related with endplate damage during intraoperative endplate preparation. Solid bone fusion was achieved in 28 out of 31 patients (90.3%).

Conclusion

With proper patient selection and careful endplate preparation, anterior cervical discectomy and fusion (ACDF) using a stand-alone PEEK cage packed with local autobone graft could be a good alternative to the standard ACDF techniques with plating.     

Bryan人工颈椎间盘置换与椎间融合治疗颈椎病的中期疗效比较

背景：国内外有许多相关报道颈人工椎间盘置换治疗颈椎病取得了非常好的近期临床疗效，但因其刚刚开展不久，缺乏长期随访结果。 目的：观察Bryan人工颈椎间盘置换治疗颈椎病的临床和影像学结果及邻近节段活动度的情况，并与椎间融合治疗方法比较。 设计、时间及地点：回顾性病例分析，于2004-10/2006-04在河北医科大学第三医院脊柱外科完成。 对象和方法：22例患者行Bryan假体置换（置换组），同期行常规颈前路椎间盘切除减压植骨融合内固定患者30例（融合组）。在术后1周、3个月、6个月、12个月、24个月进行随访，在每一次随访中拍摄颈椎前屈后伸位、左右侧屈位X射线片，观察置换组假体稳定性及融合组融合节段骨性融合情况。 主要观察指标：①材料与宿主的生物相容性。②临床疗效评估。 结果：全部病例随访最短24个月，平均30.6个月。①融合组患者术后6个月植骨全部骨性融合；内固定无松动、脱落、断裂的发生。置换组患者置换后无假体移位、脱落等并发症发生。②两组患者随访时神经功能均得到明显恢复，两组JOA评分差异无显著性意义（P > 0.05）。③置换组1例患者随访2年发生椎间自发融合，置换节段活动丢失；其余21例患者置换节段活动度与置换前差异无显著性意义（P > 0.05）。④融合组术后邻近节段的活动度较术前明显增大（P < 0.05）；而置换组置换前后邻近节段活动范围差异无显著性意义（P > 0.05）。 结论：与前路融合方法比较，中期随访结果显示Bryan人工颈椎间盘置换治疗颈椎病在取得满意临床疗效的同时能保留置换节段的活动，且避免了置换后上下邻近节段活动度的增加。     

Multilevel cervical fusion without plates, screws or autogenous iliac crest bone graft.

OBJECTIVE: This prospective study was performed to evaluate the safety and efficacy of polyetheretherketone (PEEK) cages packed with demineralized bone matrix (DBM) mixed with autologous blood and curettage microchip material for treatment of multilevel cervical disc disease and spondylosis without the use of plates, screws or autogenous iliac crest bone graft. MATERIAL AND METHODS: Sixteen patients underwent multilevel anterior cervical discectomy and fusion (ACDF) for a total of 42 levels. Minimum follow-up was 18 months. Neurological outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scoring system; cervical lordosis and cervical fusion status was assessed on X-ray. Statistical analysis was performed to compare preoperative and postoperative scores using a dependent t-test (P<0.05). RESULTS: Eight patients underwent two-level, six underwent three-level and two underwent four-level operations. The fusion rate was 90.5% and non-fusion rate was 9.5%, but reoperation was not required for these patients in the follow-up period. Cervical lordosis was preserved and neurological status was improved. No cage migration or cage failure occured. CONCLUSION: ACDF using PEEK cages packed with DBM is a safe and efficient method for treatment of multilevel cervical disc disease and spondylosis. It preserves cervical lordosis and obviates the complications related to iliac crest graft harvest and screw-plate fixation.     

Filling a cervical spine cage with local autograft: change of bone density and assessment of bony fusion

To date, it remains debatable whether cervical spine fusion cages should be filled with any kind of bone or bone substitute. Using a bone substitute would produce additional costs, using an autologous bone graft from the iliac crest would make the use of the cage at least questionable. As an alternative, cortical and subcortical bone from the anterior osteophytes of the segment in which the disc has been removed could be used to fill the cage: higher costs and complications at the iliac crest could both be avoided and the cage could be filled. However, the fate of these bone chips made from the anterior osteophytes is unclear as well as whether fusion will occur using this technique. The objective of the current study was to investigate possible changes in the bone density of this local autograft in the cage within the first 12 months after surgery by means of computed tomography. A second objective was to assess segmental bony fusion using this technique. 21 patients, suffering from degenerative disc disease of the cervical spine, were included into this prospective study. They all underwent anterior decompression, cage insertion and plate stabilisation. The cage (Rabea, Signus Medizintechnik, Alzenau, Germany), was filled with bone chips made from the anterior osteophytes of the segment that underwent discectomy. On the third day after surgery as well as three, six and 12 months after surgery, an axial computed tomography scan through the cage was taken and density within the apertures of the cage was measured in a standardised manner. Flexion-extension lateral radiographs were taken to investigate segmental fusion. Statistical significance was assumed to be at a 95 % level of significance. 23 cages were implanted. The mean value of the bone density obtained by computed tomography was 505 (+/- 119) HU on day three, 635 (+/- 156) HU after three months, 769 (+/- 162) HU after six months, and 814 (+/- 198) after 12 months. There was a significant difference when the values after 12 months were compared to those obtained after three days (p < 0.001) and after three months (p = 0.004). Bony fusion was seen in 21 out of 23 segments (91.3 %) after 12 months. It may be concluded that this technique could be an alternative to the current treatment options.