聚乙烯醇水凝胶人工髓核置入对腰椎运动影响的生物力学研究

目的：研究髓核摘除后聚乙烯醇水凝胶人工髓核置入对腰椎活动度和椎间隙高度的影响.方法：对7具新鲜成人尸体L4/5正常椎间隙、髓核摘除后和置入人工髓核后在8.0Nm扭矩下的屈伸、侧弯和旋转的活动度（ROM）、中性区（NZ）和椎间隙高度变化进行测试、比较.结果：髓核摘除后,L4/5椎间屈伸、侧弯、旋转的ROM和NZ较正常组显著增加（P＜0.05或0.01）,在0和200N的负荷下椎间隙高度较相同情况下正常组分别下降1.2mm和1.7mm;置入人工髓核后,相对于正常椎间隙,L4/5椎间屈伸、侧弯、旋转的ROM和NZ无明显差异,较髓核摘除组明显下降（P＜0.05或0.01）,在0N和200N的负荷下椎间隙高度较相同情况下髓核摘除组分别增加1.6mm和2.0mm.结论：聚乙烯醇水凝胶人工髓核置入椎间盘切除后的椎间隙可有效恢复椎间隙高度,维持腰椎节段正常的三维运动功能稳定性.     

果胶/聚乙烯醇复合水凝胶人工腰椎髓核置换的实验研究

目的 评价果胶/聚乙烯醇复合(CoPP)水凝胶人工髓核置换延缓腰椎间盘退变的效果.方法 以36只成年新西兰大白兔,建立腰椎髓核置换的动物模型,显露L3～4和L4～5两个椎间盘.L4～5椎间盘用16号针头穿刺后将聚乙烯醇(PVA)或CoPP水凝胶试件植入其内,L3～4椎间盘行假手术处理或只用针头穿刺而不植入试件.由此,全部实验椎间盘分成假手术组、穿刺组、PVA组和CoPP组.于术前、术后1、3、6个月摄腰椎侧位X线片,测量椎间盘高度指数百分比,并对手术节段椎间盘进行组织学评估.结果 实验动物均存活,无伤口感染或手术并发症发生,无PVA、CoPP假体试件突出或明显移位.PVA组和CoPP组椎间盘高度丢失明显小于穿刺组(P<0.01),与假手术组相比差异无统计学意义(P>0.05).PVA、CoPP两组在术后6个月内椎间盘退变的程度无明显差异,但随着术后观察时间的延长,两者治疗效果的差别逐渐增大,PVA组椎间盘退变明显,CoPP组退变相对缓慢.结论 CoPP水凝胶人工髓核置换术可保留椎问盘高度和填充髓核空间,延缓纤维环的退变,具有潜在的临床应用价值.     

果胶/聚乙烯醇复合水凝胶的生物力学评价

目的评价果胶/聚乙烯醇复合(CoPP)水凝胶的生物力学性能,为研制新型人工髓核提供依据.方法制备圆柱状CoPP、聚乙烯醇(PVA)水凝胶试件,在生物力学试验机上纵向加载,实时采集力、位移,测量加载前、卸载后质量、尺寸,计算弹性模量、能量吸收率、归一化蠕变量及归一化质量、体积百分比.结果CoPP水凝胶弹性模量为(2.76±0.09)MPa,显著小于相应浓度PVA水凝胶的弹性模量(4.89±0.61)MPa,CoPP水凝胶能量吸收率是PVA水凝胶的1.46倍.持续加载30min,CoPP、PVA水凝胶均达到蠕变平衡.卸载后即刻,CoPP水凝胶归一化质量百分比为(97.67±0.98)%,显著小于PVA水凝胶的(99.15±0.18)%.卸载后24h,CoPP、PVA水凝胶归一化质量百分比、体积百分比与加载前无显著性差异.结论CoPP水凝胶是一种软而韧、缓冲载荷能力较强、渗透性好的粘弹性材料,可用于研制成形人工髓核假体.     

腰椎间盘人工髓核置换术

髓核是椎间盘重要组成部分,其可以保持椎间盘高度、缓冲脊柱震荡、维持脊柱运动功能.因此对于椎间盘突出症,人们很早就开始设想采用人工髓核的方式进行置换,以保持椎间盘的功能,并在临床上有初步应用.但是由于人工髓核材料的问题,椎间盘人工髓核置换术并没有得到广泛开展.最近,Raymedica公司开发了椎间盘髓核假体(Prosthetic Disc Nucleus,PDNR),该髓核假体由高分子聚乙烯外套和处于其内的半流动性水凝胶(聚丙烯腈-聚丙烯酰胺共聚物)组成,其完全膨胀后可吸收本身重量80%的水分,而且其容积可随载荷而变化.目前该项腰椎间盘人工髓核假体置换术(简称PDN手术)已在欧洲广泛开展,全球已有1000多例患者接受了PDN手术.作者结合临床初步应用对该手术进行介绍.     

腰椎间盘人工骨核置换术

髓核是椎间盘重要组成部分 ,其可以保持椎间盘高度、缓冲脊柱震荡、维持脊柱运动功能。因此对于椎间盘突出症 ,人们很早就开始设想采用人工髓核的方式进行置换 ,以保持椎间盘的功能 ,并在临床上有初步应用。但是由于人工髓核材料的问题 ,椎间盘人工髓核置换术并没有得到广泛开展。最近 ,Ｒａｙｍｅｄｉｃａ公司开发了椎间盘髓核假体 (ＰｒｏｓｔｈｅｔｉｃＤｉｓｃＮｕ ｃｌｅｕｓ ,ＰＤＮＲ) ,该髓核假体由高分子聚乙烯外套和处于其内的半流动性水凝胶 (聚丙烯腈—聚丙烯酰胺共聚物 )组成 ,其完全膨胀后可吸收本身重量 80 %的水分 ,而且其…     

人工髓核假体置换术治疗腰椎间盘突出症

目的 比较人工髓核假体（PDN）置换术和传统单纯髓核摘除术治疗腰椎间盘突出症的疗效,评价人工髓核假体置换术的实用价值。方法 施行人工髓核假体置换术18例,16例为单节段腰椎问盘突出症,2例为两节段腰椎间盘突出,均采用单枚PDN置人单个椎间盘间隙。对照组单纯髓核摘除术30例,22例为单节段腰椎间盘突出,8例为两节段腰椎间盘突出。观察两组病例的临床效果。结果 PDN组术后临床症状均消失,运动功能明显好转。6例获得9～22个月的随访,9例获得3～9个月的随访,椎间隙高度较手术前平均增加10．5％,无髓核假体移位突出,术后疗效明显优于单纯髓核摘除术组,两者相比差异有显著性（P〈0．01）。结论 PDN置换术既能恢复脊柱的节段稳定性,又保持脊柱节段的活动性,适当的假体设计与材料选择也能使椎间盘与椎体后柱的负荷获得再平衡,有广泛的应用前景。     

水凝胶人工髓核应用于椎间盘退变的研究进展

椎间盘退变是造成下背部疼痛的重要原因,其发病机制复杂,应用髓核假体可以较好的模拟自身正常的髓核组织,在临床上取得了较好的短期效果。水凝胶因其出色的力学特性以及不发生免疫排斥反应等优点而成为髓核假体的热门材料。而应用干细胞复合可降解水凝胶再造髓核,也为椎间盘退变的治疗提供了新的思路。     

腰椎间盘突出人工髓核置换术的生物力学测试

目的 对腰椎间盘人工髓核置换术进行生物力学评价，为临床应用提供理论依据。方法 取6具新鲜成人尸体腰椎标本（L1～S1），制成三种L4～L5运动节段的试验模型：正常腰椎，椎间盘髓核切除术后，人工髓核植人术后，分别对其进行生物力学测试，记录不同运动状态下脊柱节段运动范围（ROM）的改变情况。结果 与正常脊柱组比较，去髓核组运动节段活动明显增大（P〈0．05），稳定性下降，人工髓核植入组与去髓核组比较运动节段活动明显减小（P〈O．05），与正常脊柱组相比较，运动节段活动差异无显著性（P〉0．05）。结论 腰椎椎间盘人工髓核的植人能较好地恢复腰椎间盘髓核摘除后运动节段的生物力学稳定性。     

假体置入与聚丙烯酰胺水凝胶注射隆乳术并发症临床观察

目的:观察经腋路胸大肌后间隙假体置入隆乳术后与医用聚丙烯酰胺水凝胶(PAHG)乳腺后间隙一点注射法注射隆乳术后并发症的发生情况,以分析两种手术的优缺点。方法:对2001年-2002年间在本院行隆乳手术的183例患者(经腋路胸大肌后间隙假体置入隆乳术者130例、医用聚丙烯酰胺水凝胶乳腺后间隙注射隆乳术者53例)进行随访观察,了解并发症的发生情况。结果:假体置入组130例,平均年龄31.25岁±6.13岁,发生各种并发症5例,发生率3.85％;水凝胶注射隆乳组53例,平均年龄33.66岁±5.27岁,发生各种并发症12例,发生率22.64％。结论:两组术后并发症发生率差异显著(P<0.01),注射组并发症发生率明显高于假体置入组,假体置入法隆乳术仍应作为目前隆乳术的主流选择。     

腰椎间盘人工髓核置换术在临床中应用

目的观察腰椎间盘人工髓核(PDN)置换在腰椎间盘突出症患者中的应用效果.方法对11例腰椎间盘突出症患者在摘除髓核的同时,植入由Raymedica公司提供的PDN,并定期随访观察.结果随访6个月,11例患者恢复良好,椎间隙高度保持,腰椎活动正常,未见假体脱出及对 PDN材料产生过敏或排斥反应.结论 PDN接近正常人体髓核功能,不影响原来椎间盘髓核摘除术后的疗效,是目前置入椎间隙替代髓核的较好的材料,远期疗效有待进一步观察.     

不同固定表面生物型人工膝关节假体的骨长入实验研究

目的比较人工膝关节不同孔径的固定表面生物型假体植入兔体内的骨长人情况,为人工膝关节生物学固定方法的改进提供理论依据。方法自行设计制作兔部分限制型人工全膝关节表面置换假体,股骨髁和胫骨平台假体固定表面用激光焊接两层不锈钢网,一组设计为两层不锈钢网孔大小相同,网孔均为（2×2）mm,称大孔假体（实验组假体）。另一组设计为两层不锈钢网孔大小不同,大网孔大小为（2×2）mm,小网孔大小为（1．5×1．5）mm,大网孔钢网焊接在紧贴假体固定表面,小网孔叠放在其外面,称小孔假体（对照组假体）。两组假体两层钢网均错开焊接。30只成年新西兰大白兔随机分成两组,每组15只,分别行左侧人工膝关节置换术,髌骨不置换。术后1、3、6个月处死动物取材,每个时间点各5只,进行硬组织切片染色,计算假体骨界面新生骨形成率,假体与骨界面的骨结合率。结果假体骨界面新生骨形成率,假体与骨界面的骨结合率,实验组大于对照组（P〈0．05）。结论生物型人工膝关节假体的固定表面孔径不同影响假体与骨界面的骨长人,大孔假体骨界面新生骨形成率及假体与骨界面的骨结合率要优于小孔假体。     

骨髓间充质干细胞-壳聚糖凝胶复合体移植治疗椎间盘退变

目的 观察兔骨髓间充质干细胞.壳聚糖凝胶复合体移植修复椎间盘髓核缺损退变的效果.方法 建立兔椎间盘髓核缺损退变模型,将兔骨髓间充质干细胞-壳聚糖凝胶复合体注射移植入缺损退变模型中,兔继续培养4周后处死,取出移植修复的椎间盘进行组织HE染色、Aggre-can番红O染色及Ⅱ-collagen免疫组织化学染色,与正常椎间盘及未行移植的缺损退变椎间盘进行随机对照,检测移植修复的效果.结果 骨髓间充质干细胞-壳聚糖凝胶复合体可以在缺损的椎间盘中正常生长,并呈现向类髓核细胞分化的趋势,合成分泌Ⅱ-collagen和Aggrecan,维持原椎间盘髓核组织的生物学特性,而缺损退变组髓核组织纤维化、完整性丧失,水分丢失,Ⅱ-collagen合成明显减少(P<0.05).结论 兔骨髓间充质干细胞-壳聚糖凝胶复合体能够修复椎间盘缺损退变.     

Comparison of neuropathic pain induced by the application of normal and mechanically compressed nucleus pulposus to lumbar nerve roots in the rat.

We studied whether applying nucleus pulposus tissue, obtained from tail intervertebral discs that had been subjected to chronic mechanical compression, to the lumbar nerve roots produces hyperalgesia, which is thought to be a pain-related behavior in the rat. An Ilizarov-type apparatus was used for immobilization and chronically applied compression of the rat tail for eight weeks. Three weeks after application of extracted nucleus pulposus tissue on the lumbar nerve roots, motor function, sensitivity to noxious mechanical stimuli was measured. Eight weeks after application of the apparatus, the instrumented vertebrae were resected and sections were stained with hematoxylin and eosin to evaluate degeneration of the intervertebral disc. Mechanical hyperalgesia observed in rats treated with the compressed nucleus pulposus tissue was greater and of longer duration than in the rats treated with normal and non-compressed discs. The nucleus pulposus in the instrumented vertebrae showed some histological degeneration. In conclusion, chronic mechanical compression of nucleus pulposus, which resulted in degeneration to some extent, enhanced mechanical hyperalgesia, which was induced by application of nucleus pulposus on the nerve root in the rat. Degenerative intervertebral discs might induce more significant pain than normal intervertebral discs.     

Biomechanical changes of the lumbar intervertebral disc after automated and nonautomated percutaneous discectomy: an in vitro investigation

Summary A total of 40 human lumbar motion segments were prepared and tested in an electromechanical materials testing machine to investigate the biomechanical changes, i.e., intradiscal pressure, radial extension, and height of the intervertebral disc, after percutaneous discectomy. In 20 discs (group A) the nuclear material was excised using the nonautomated percutaneous lumbar discectomy technique (NAPLD). In the other 20 (group B) the material was removed with the automated percutaneous lumbar discectomy method (APLD). The results of the two groups were analyzed statistically and compared to each other. In the NAPLD group the removal of 0.1 g freeze-dried nucleus pulposus material reduced the height of the disc an average of 0.32 mm, versus 0.47 mm in the APLD group. The radial bulge increased in both groups after the removal of 0.1 g freeze-dried nucleus pulposus material, on average 0.10 mm versus 0.15 mm. The intradiscal pressure also decreased in both groups after the removal of 0.1 g freeze-dried nucleus pulposus material, on average 0.94 bar versus 1.88 bar. The differences between the biomechanical data of the two groups were statistically significant for all three parameters (P<0.05). Our results show that the mechanism for improving radicular pain in patients with herniated disc after treatment with percutaneous discectomy is still in question. We postulate that loss of height of the disc and, as a consequence, reduction of tension in the affected nerve root, plays a major role with regard to this improvement.     

The inner prosthetic surface structure and re-endothelization: An experimental study in the rat using two types of microvascular prostheses for aortic implantation

Two types of microvascular prostheses were implanted in the rat infrarenal aorta. Operations were carried out with clean, nonsterile instruments under ether anesthesia. Anastomoses were made with a continuous 8-0 suture. In group A, a 1-cm-long piece of expanded polytetrafluorethylene (PTFE) and in group B a 1-cm-long fibrous polyurethane prosthesis were implanted. Both groups consisted of 18 rats. Three rats from each group were killed at days 3, 5, 10, 20, 40, and 60 postimplantation. Prostheses were examined by scanning electron and light microscopy for the re-endothelialization. All prostheses in both groups were patent at the time of death. Reendothelialization started in both types of prostheses the fifth day after implantation and had advanced 1–3 mm in the PTFE prostheses at day 60. However, in the fibrous polyurethane prostheses, re-endothelialization progressed and a complete new lining was achieved between days 20 and 40 postimplantation. The endothelium/neointima in the fibrous prosthesis was firmly anchored onto the prosthetic wall by means of cellular protrusions between the polyurethane fibers. In contrast to this observation, the endothelium/neointima developed in the PTFE prostheses was not anchored to the wall of the prosthesis. It is emphasized that the development of a new lining in a prosthesis may reduce the risk of endogenous, hematogenous infections. From the results of this study, we have concluded that there is a correlation between the inner surface structure and the extent of the reendothelialization of a prosthesis. A prosthesis with a fibrous structure is much more rapidly and completely re-endothelialized than an expanded PTFE prosthesis.     

Experimental studies of the esophageal prosthesis with a polyvinyl alcohol hydrogel

Though various prosthetic materials have been experimented with for use as an artificial esophagus in the past, the two main problems that have prevented successful clinical implantation of such a prosthesis were anastomotic leakage and stricture formation of the artificial esophagus. The purpose of this study is to evaluate a high water content polyvinyl alcohol hydrogel (PVA-H) for use as the esophageal prosthesis. In 10 adult mongrel dogs, the defect after resection of the intrathoracic esophagus was bridged with a PVA-H esophageal prosthesis, 5.5 cm in length and 15 mm in internal diameter with two Tefron rings, installed 2 cm from each end. The esophageal prostheses, including the anastomotic lines, were enveloped by Dacron mesh after implantation. After implantation, the prostheses were examined endoscopically and fluoroscopically. The dogs, which were sacrificed or had died, were evaluated macro- and microscopically. Among the six dogs underwent operation, one is still living 900 days after implantation. The other two dogs were sacrificed on 165 and 162 days after implantation. The remaining three dogs died of postoperative complications ranging from 25 to 81 days after implantation. The causes of death were the respiratory insufficiency after endoscopical examination, abscess formation around the prosthesis and pyothorax. Up to 2 months after implantation the esophageal prostheses were fixed to the host esophagus without stenosis. However, the prostheses were gradually dislodged due to constricture depending on the growing granulation at the proximal anastomosis. When the surviving dog was examined on the 376th day after the operation, the esophageal prosthesis fell off entirely.(ABSTRACT TRUNCATED AT 250 WORDS)     

TGF-β3修饰退变髓核细胞移植修复兔退变椎间盘的效果观察

目的探讨TGF-β3基因修饰后退变髓核细胞生物学效应以及植入兔退变椎间盘后对退变椎间盘的影响。方法将重组腺病毒载体Ad-TGF-β3与第2代退变髓核细胞按10∶1比例混合培养转染(Ad-TGF-β3组),待细胞融合后传代,MTT检测转染细胞增殖活性,Western blot检测TGF-β3蛋白含量,免疫细胞化学染色观察对数生长期转染细胞Ⅱ型胶原染色阳性率;采用病毒空载体转染髓核细胞(Adv组)和未经转染髓核细胞(空白组)作为对照。取30只新西兰兔,体重3.2～3.5 kg,雌雄不限,通过针刺L3、4、L4、5和L5、6椎间盘制备椎间盘退变模型。将实验动物按照随机数字法分为3组,转染细胞组(A组,n=12)、退变细胞组(B组,n=12)和空白对照组(C组,n=6)。A、B组将100μL浓度为1×105个/mL对应细胞悬液注射入退变椎间盘,C组同法注入等量PBS。注射后6、10、14周取A、B组各4只、C组2只实验动物处死,取L3、4、L4、5和L5、6椎间盘行组织学观察,RT-PCR检测Ⅱ型胶原和蛋白多糖mRNA表达。结果 Ad-TGF-β3转染后髓核细胞活性明显改善;转染后3、7、14 d,TGF-β3在髓核细胞内表达逐渐升高;Ad-TGF-β3组髓核细胞细胞质内见棕黄色Ⅱ型胶原阳性染色,阳性率显著高于Adv组及空白组(P<0.05)。组织学观察示,A组椎间盘退变程度较B、C组明显减轻。6、10、14周A组Ⅱ型胶原和蛋白多糖mRNA表达显著高于B、C组,差异均有统计学意义(P<0.05)。结论 TGF-β3基因修饰退变髓核细胞后可明显改善细胞生物活性,转染后髓核细胞植入兔体内可明显增加退变椎间盘的基质分泌。     

Stiffness of prosthetic nucleus determines stiffness of reconstructed lumbar calf disc.

BACKGROUND CONTEXT: Currently, artificial spinal discs require transection or partial removal of the annulus fibrosis in order to excise the nucleus and implant a prosthetic nucleus or implant a total disc device, respectively. Preservation of the annulus for prosthetic disc replacement maintains the function of the annulus and may improve annulus load sharing with the prosthesis. PURPOSE: To quantify the biomechanical characteristics of an annular sparing intervertebral prosthetic disc (IPD) in a lumbar calf spine model. The aim of the study was to determine whether altering the stiffness of the elastic component of this unique prosthesis would correspond to changes of the overall reconstructed disc. STUDY DESIGN/SETTING: A biomechanical study was conducted in vitro using cadaveric calf spines such that each specimen served as its own control. Investigations were performed at the Minneapolis Medical Research Foundation, Orthopaedic Biomechanics Laboratory. METHODS: Six L45 or L56 motion segments (from which the posterior elements had been removed) were studied in axial compression, sagittal and lateral bending and torsion. These load states were applied to the intact, denucleated and prosthetically reconstructed disc using four IPDs of differing stiffness. RESULTS: Load-displacement testing demonstrated that stiffer IPDs resulted in a decreased range of motion and neutral zone, and greater stiffness of the reconstructed disc. Disc reconstruction with the stiffest IPD approximated the behavior of the intact disc. CONCLUSIONS: The overall biomechanical characteristics of a reconstructed disc are related to the stiffness of a nucleus prosthesis. The similarities in the mechanical behavior of reconstructed and intact discs suggest that additional feasibility studies for the annulus-sparing IPD are warranted.     

The effect of posture on the fluid content of lumbar intervertebral discs

Cadaveric lumbar motion segments were creep loaded for 4 hours, and the fluid content of the intervertebral discs was measured and compared with that of unloaded discs. Half of the specimens were wedged to simulate sitting with the lumbar spine flexed, and the other half were wedged to simulate sitting or standing erect. The results showed that "flexed" discs lost more fluid, especially from the nucleus pulposus, than did the "erect" discs. It is concluded that fluid flow in flexed postures can aid the nutrition of the lumbar discs.