【作者】 陈宇；

【导师】 陈德玉； 袁文； 倪斌； 叶晓健； 王新伟；

【作者基本信息】 第二军医大学 ， 外科学， 2009， 博士

【摘要】 背景:颈椎伤病的治疗关键在于减压以及减压后颈椎的稳定性重建,即根据患者具体病情,通过手术去除患者不同节段的颈椎致压物,而后采用酌情选择不同的植骨、融合技术,恢复维持手术节段的稳定性,其中前者决定患者手术后近期疗效,而后者是获得良好远期疗效的保证。目前颈前路椎体次全切除减压植骨融合术在临床上被广泛应用于颈椎退变、创伤、肿瘤等多种伤患。减压后采用钛网的原位植骨重建方式由于其操作相对方便,避免了供骨区并发症,同时具有较高的植骨融合率,因此在临床上使用较为普遍。然而,术后钛网发生沉陷的比例相当高,并有可能导致原有颈椎生理曲度和椎间高度的丢失,造成术后患者出现颈肩部酸痛,神经功能恢复停止或再次加重,甚至出现颈椎后突畸形,融合固定失败等严重并发症,需要再次手术。目前普遍认为钛网其外形设计上的缺陷是造成沉陷发生的重要原因。因此,有必要对影响患者术后钛网沉陷的相关因素及其临床意义进行研究,并设计一种新型钛网来避免术后沉陷,以提高手术疗效。目的:通过本课题的研究进一步明确影响颈前路钛网植骨重建术后钛网沉陷的相关因素及其临床意义,在总结现有钛网缺陷的基础上,结合现代颈前路植骨融合材料的设计理念,设计和研制新型的全接触式植骨重建钛网,并通过计算机模拟技术建立颈前路椎体次全切除钛网植骨重建手术的三维有限元模型,与现有钛网进行对比,通过相关生物力学分析,验证新型钛网的安全性和有效性。方法:(1)收集120例采用颈前路椎体次全切除减压钛网植骨融合术治疗的颈椎患者临床及影像学资料,分析患者年龄、性别、融合节段、钢板类型、垫片使用等因素对钛网沉陷的影响;探讨钛网沉陷与患者颈椎曲度丢失、神经功能改善不佳、颈肩痛、内固定失败等问题的关系。(2)分析颈前路椎体次全切除减压钛网植骨融合术后钛网沉陷的原因,在总结现有钛网缺陷的基础上,参考国人正常颈椎椎体上、下终板倾斜角等解剖数据,设计并研制新型全接触式植骨重建钛网,扩大钛网-椎体终板接触面,以期避免术后钛网沉陷;(3)以现有钛网为研究对照,建立使用两种不同钛网的椎体次全切除植骨重建手术的三维有限元模型;比较其生物力学应力分布差异。结果:(1)随访发现96例(79.7%)患者术后出现钛网沉陷,其中包括73(60.7%)例轻度沉陷(1～3mm)和23(19.0%)例严重沉陷(> 3mm)。双节段椎体次全切除减压钛网植骨重建较单节段更易出现钛网沉陷(p <0.001)。严重的钛网沉陷可降低患者手术疗效,并导致患者出现颈肩痛、症状复发、内固定失败等并发症;(2)分析导致患者术后钛网沉陷的原因可能包括:患者自身骨质疏松、终板刮除过多、过度撑开、钛网-终板接触不贴附、接触面小、钛网修建不当,其中患者自身骨质疏松、终板刮除过多和过度撑开可通过术前病例筛选、改进手术技术等加以避免,然而目前现有钛网外形上的固有缺陷难以解决。结合现代颈前路植骨融合材料的设计理念,设计了新型全接触式植骨重建钛网,由钛合金制成,由柱状主体及上、下端面组成。柱状主体设计与现有钛网相似,两端与上、下端面相连。上端面为环形,在矢状面上向上拱起呈穹窿状,外圈为一环形加厚结构,下端面同样为环状,矢状面上呈向后上方倾斜,外圈为一环形加厚结构。设计上考虑到不同患者椎体大小、形态上的个体差异可制成不同规格型号的产品。在实际使用中,根据减压槽的长度和宽度可选用不同型号的钛网,避免术中修剪造成钛网终板接触面锐利。新型钛网通过扩大钛网-椎体终板接触面,避免术后钛网沉陷。(3)建立了两种颈前路C5椎体次全切除减压钛网植骨重建手术的三维有限元模型,在屈曲、侧屈及扭转三种载荷工况下,采用新型钛网可降低钛网椎体终板接触面及钢板表明应力分布,减少C4、C6椎体相对位移。结论:钛网沉陷是颈前路椎体次全切除钛网植骨重建术后常见现象,严重的钛网沉陷可降低患者的手术疗效,产生严重并发症;由于目前临床所使用的钛网设计上的缺陷是钛网沉陷的重要原因,并且难以完全解决,所设计的新型全接触式植骨重建钛网进一步扩大钛网-椎体终板接触面,可有效增加手术节段的稳定性,避免术后钛网沉陷。更多还原

【Abstract】 Summary of Background Data: Decompression and reconstruction of the cervical stability are the key points in the treatment of cervical diseases or injuries. It means that the surgeons need to remove all the compressive matters at different levels according to the different condition of different patients, and also have to choose suitable techniques of bone graft and fusion to maintain the stability of the cervical spine. The first one is responsible for the immediate clinical results and the second one will promise the better long-term outcome. Recently, the operation called“anterior cervical corpectomy and fusion (ACCF)”has been widely used in the treatment of cervical degenerative diseases, cervical injuries and cervical tumors in the clinical practice. After decompression, one kind method of autogenous local bone graft with titanium mesh cage (TMC) has been widely used, because it has the advantages of convenient employment, less related complications of harvesting bone block from the iliac crest and higher bone fusion rate. However, postoperative subsidence of TMC has been found in most patients with ACCF using TMC, which could lead to loss of cervical lordosis and intervertebral height, and even more subsidence-related complications, including neck pain, neurologic deterioration and instrument failure. The patients sometimes need revision surgery. At present, the design defects of the current TMC were widely considered as one of most important reason for the postoperative subsidence, which could be very difficult to be resolved by other salvage measurement. For this reason, a new type of full-contact TMC was designed to avoid subsidence and increase surgical results of ACCF.Objectives: To clarify the risk factors for the subsidence of the titanium mesh cage (TMC) after anterior cervical corpectomy and fusion, and to discuss their clinical correlation. On the basis of summary the defects of the current TMC and with the design of the modern bone grafting materials used in the cervical spine, to design and manufacture a new type of full-contact TMC, and make sure its safty and effect by a finite element study using computer simulation technique. The characteristics of stress distribution of new full-contact TMC were analyzed when compared with the current TMC.Methods: (1) A total of 120 patients with anterior cervical corpectomy and TMC fusion were included in the first part of this study. TMC subsidence, radiologic findings, and clinical results were evaluated in the 12-month follow-up period. Risk factors including age, sex, level of corpectomy, type of plate and using end caps were evluated, and also discuss the correlation of TMC subsidence with neck pain, neurologic deterioration and instrument failure. (2) The reasons for subsidence of TMC after ACCF were analyzed in the details in the second part of this study. On the basis of the study of defect of current TMC and reference to the anatomic data of normal Chinese patients such as the gradient of vertebral endplates in the cervical spine, a new type of full-contact TMC was designed and manufactured to avoid subsidence by enlarging the contact area of TMC and the vertebral endplates. (3) A finit element analysis was carried out to compare the biomechanical characteristics of two different kinds of TMC. The difference of stress distribution was recorded.Results: (1) After follow up, subsidence of TMC was found in 96 (79.7%) patients, including mild subsidence (1 to 3 mm) in 73 (60.7%) patients and severe subsidence ( > 3 mm) in 23 (19.0%) patients. Two-level corpectomy was more susceptible to severe subsidence when compared with 1-level corpectomy (p < 0.001). Japanese Orthopedic Association recovery rate for severe subsidence was significantly lower than that for no subsidence (p=0.010). Severe subsidence was correlated with subsidence-related complications, including neck pain, neurologic deterioration, and instrument failure. (2) The reasons for postoperative subsidence of TMC after ACCF could included osteoporosis, over remove of vertebral endplates, over distraction, no-match of TMC and vertebral endplate, small contact area and unsuitable clip of TMC. The first three reasons could be resolved by preoperative selection of patients and improve surgical technique during operation, but the inherent defects of the current TMC are difficult to be resolved. For this reason, the new type of full-contact TMC was designed with the design of the modern bone grafting materials used in the cervical spine. The new full-contact TMC used titanium allegation, which was structured by one main cylinder and upper and lower ending part. The main cylinder is similar with the current TMC and connected with the upper and lower ending part. The upper ending part is ring form and characterized by fornix formation in the sagittal plane. The lower ending part is also ring form and characterized by obliquity in the sagittal plane. Both the upper and lower ending part were thickened at the external ring to enlarge the contact area with vertebral endplates. With the consideration of different sizes of cervical vertebral body, the new TMC was designed with different sizes with the advantage of no more clipping before using it, which could be helpful to avoid subsidence of TMC. (3) Two finite-element models of C5 anterior cervical corpectomy and fusion with new and current TMC were reconstructed. Analytic results showed using new TMC could reduce the stress of TMC-endplate contact and anterior cervical plates, it also could reduce the relate displacement between C4 and C6 vertebrae.Conclusions: TMC subsidence was a common phenomenon after anterior cervical corpectomy and fusion with TMC. Severe subsidence might have led to bad clincial results and subsidence-related complications. The design defect of current TMC was one of the most important reasons for this problem and could not be resolved by other salvage measurement. The new full-contact TMC designed to enlarge the contact area between the TMC and vertebral endplates, which are useful in maintain of the cervical stability and avoidance of postoperative subsidence.更多还原