斜外侧椎间融合术融合器沉降对腰椎生物力学影响的有限元分析

【摘要】 目的：应用三维有限元法分析椎间融合器（cage）沉降对斜外侧椎间融合术（oblique lateral interbody fusion,OLIF）术后腰椎生物力学的影响。方法：根据1例健康成年人腰椎CT扫描数据构建正常腰椎L3~L5节段三维有限元模型,模拟进行L4/5节段OLIF手术,根据cage沉降陷入椎体程度（0、1%~25%、26%~50%、51%~75%、76%~100%）分为5个等级（Grade0、Grade1、Grade2、Grade3、Grade4）,共构建10组模型（单纯cage沉降组5组、附加后路双侧椎弓根钉棒固定的钉棒组5组）。固定L5椎体下表面,设定400N的预加载荷于L3椎体上表面,再施加10N·m的力矩来模拟脊柱的前屈、后伸、侧屈、旋转运动。对腰椎在不同生理运动下L4/5节段活动度（range of motion,ROM）、cage应力峰值和内固定钉棒应力峰值进行分析。结果：模型在不同生理运动下L3/4和L4/5椎体的ROM与已发表的尸体研究类似,证明了模型的有效性。对模型施加载荷的6种运动状态中,沉降组Grade3的ROM最大,cage最大应力峰值发生在Grade2前屈运动时,达到了82.7Mpa,相较Grade0增加了241%。在附加椎弓根钉棒后脊柱ROM及cage应力峰值均减小,尤以Grade2变化最为显著,与未附加内固定相比,Grade2平均ROM下降了63%,后伸运动下cage应力峰值减小51%。结论：cage沉降对腰椎生物力学影响较大,其中cage沉降51%~75%时脊柱稳定性最差,cage沉降26%~50%时cage进一步塌陷风险最高,附加内固定钉棒后可增加脊柱稳定性并降低沉降风险。     

腰椎单侧椎弓根螺钉固定的三维有限元分析

目的:建立人正常L3～L5节段三维有限元模型,分析腰椎单侧椎弓根螺钉固定融合的生物力学特性.方法:基于人正常L3～L5节段的CT扫描数据,利用Geomagic Studio 9.0、Simpleware 2.0、Abaqus 6.7软件建立人正常L3～L5三维有限元模型(INT),并在此基础上分别建立L4/5单侧椎弓根螺钉内固定加后外侧植骨融合模型(M1)、单侧椎弓根螺钉内固定加单枚融合器置入模型(M2)及双侧椎弓根螺钉内固定加单枚融合器置入模型(M3).在L3上表面施加500N预载荷,再施加10N·m的力矩模拟腰椎前屈、后伸、侧屈及旋转等生理活动,观察不同工况下L4-L5节段角位移、椎弓根螺钉及融合器应力分布情况.结果:各工况下M1、M2、M3角位移均较INT减少,M3减少最明显;除右屈和后伸外,其他工况下M2与M3的角位移减少程度相当,而M1在左、右侧屈及左、右旋转时稳定性较差.M1的螺钉应力峰值明显高于M2和M3,尤以左屈及后伸载荷时螺钉应力峰值最大,M2螺钉应力峰值高于M3.M2椎间融合器的应力峰值在各种工况下均高于M3.结论:单侧椎弓根螺钉固定不能很好地控制侧屈和旋转载荷,椎弓根螺钉承受较大的应力;附加单枚融合器置入可以重建融合节段的稳定性,明显减少螺钉的应力.     

腰椎滑脱后路不同融合术式的有限元研究

目的 建立L4.5，滑脱节段的有限元模型，研究椎弓根螺钉内固定加后外侧植骨融合、椎弓根螺钉内固定加双枚椎间融合器（cage）植入及椎弓根螺钉内固定加单枚融合器植入等3种融合术式的固定节段的稳定性。方法 选择一名56岁退变性腰椎滑脱女性患者，以k节段为研究对象，采用螺旋CT对其进行层厚1．0mm的连续水平扫描，将所得图像进行轮廓提取和阈值分割后，借助Ansys9．0软件，建立L4.5滑脱节段三维非线性有限元模型。同时根据椎弓根螺钉、融合器的几何尺寸，分别建立其相应的有限元模型。在此基础上，根据临床术式将上述模型进行不同组合，分别建立椎弓根螺钉固定加后外侧植骨融合、椎弓根螺钉固定加双枚融合器植入及椎弓根螺钉固定加单枚融合器植入等3种腰椎滑脱后路融合术式的有限元模型，然后分别施加压缩、前屈、后伸、侧屈及旋转等各种生理载荷，观察各模型不同载荷下螺钉、融合器的应力分布及融合节段的角位移变化，由此比较各模型的稳定性。结果 后外侧植骨融合术式的螺钉应力和角位移明显高于椎体间融合术（P〈0．01）；椎弓根螺钉内固定加单枚融合器植入与椎弓根螺钉内固定加双枚融合器植入两组之间螺钉应力、融合器应力及固定椎体的角位移的差异无统计学意义（P〉0．05）；各模型固定节段螺钉及融合器的最大有效应力均出现于前屈时。结论 椎弓根螺钉内固定加单枚或双枚融合器植入的稳定性优于椎弓根螺钉内固定加后外侧植骨融合；对于椎体间融合，植入单枚融合器和双枚融合器的稳定性无明显差别。     

单枚融合器与单钉棒系统微创术式的有限元研究

目的 探讨融合器放置方法对单钉棒固定系统各结构单元、对侧小关节应力分布的影响.方法 建立腰椎功能节段及椎弓根螺钉及融合器的三维有限元模型,将其叠加后获得融合器垂直放入及斜向放入的单侧固定TLIF术式有限元模型,加载后测试系统在前屈、后伸、左屈、右屈及左旋、右旋等各工况下融合器、螺钉、钛棒及对侧小关节应力分布情况.结果 ①融合器无论是垂直放入还是斜向放入,椎弓根螺钉的载荷分布情况无明显差异;②融合器斜向放入时,可以明显改善右侧弯及前屈状态下的对侧小关节的应力分布;③融合器斜向放入可以明显改善后伸状态下融合器及终板的应力分布;并可改善左旋状态下钛棒的应力分布.结论 在实施单侧的TLIF术式时,融合器合理的放置方式应该是斜跨中线放置,这样不仅有助于改善系统的整体应力分布,同时有助于降低终板的应力峰值,从而减小终板塌陷;并减小对侧小关节的应力载荷,降低对侧小关节紊乱和术后腰痛的发生率.     

椎弓根钉内固定联合椎体成形术治疗骨质疏松性胸腰椎爆裂骨折的三维有限元研究

目的采用有限元方法比较骨质疏松性胸腰椎爆裂骨折在椎弓根钉内固定联合椎体成形术与椎弓根钉结合伤椎置钉内固定术后的生物力学稳定性。方法建立骨质疏松性L_1椎体爆裂骨折有限元模型,模拟短节段椎弓根钉联合椎体成形术(A组)以及椎弓根钉结合伤椎置钉内固定术(B组),比较2组前屈、后伸、侧屈、旋转载荷下L_1椎体最大位移及内固定物最大应力值。结果在前屈、后伸、侧屈、旋转载荷下,L_1椎体最大位移见于前屈载荷,2组前屈、后伸、侧屈、旋转载荷下L_1椎体最大位移比较差异无统计学意义(P0.05)。在前屈、后伸及侧屈载荷时,内固定物应力最大值为下位螺钉尾部与钛棒联接处,A组前屈、后身、侧屈内固定应力较B组小,差异有统计学意义(P0.05);在旋转载荷时,A组内固定物应力最大部位仍为下位螺钉尾部与钛棒联接处,B组内固定物应力最大部位为伤椎螺钉尾部与钛棒联接处,A组旋转内固定物应力较B组小,差异有统计学意义(P0.05)。结论椎弓根钉内固定联合椎体成形术治疗骨质疏松性胸腰椎爆裂骨折生物力学稳定性强,可获得比椎弓根钉结合伤椎置钉内固定术更小的内固定物应力,能有效防止内固定物失效。     

脊柱骨折经伤椎椎弓根置钉附加横连短节段固定的稳定性测试

目的:探讨脊柱骨折经伤椎椎弓根置钉附加横连短节段钉棒固定的稳定性.方法:5具新鲜冰冻小牛腰椎标本(L1～L5)制备成L3椎体爆裂骨折模型,依次进行单纯经伤椎和上下相邻椎体椎弓根置钉短节段6钉固定(单纯经伤椎6钉固定组)和附加横连经伤椎和上下相邻椎体椎弓根置钉短节段6钉固定(附加横连经伤椎6钉固定组),测试L2～L4损伤前(对照组)、损伤后(骨折组)及单纯经伤椎6钉固定组和附加横连经伤椎6钉固定组的三维6个方向的运动范围(ROM),比较各组间的差异.结果:L3椎体爆裂骨折后L2～L4各方向的ROM明显增加,与损伤前比较均有显著性差异(P<0.05);单纯经伤椎6钉固定组与附加横连接经伤椎6钉固定组各方向的ROM均明显减小,与骨折组相比均有显著性差异(P<0.05),在前屈、后伸、侧弯运动方向的ROM小于对照组,差异有显著性(P<0.05),旋转方向上大于对照组(P<0.05).两种固定方式在前屈、后伸、侧弯方向上的ROM无显著性差异(P>0.05),附加横连经伤椎6钉固定组较单纯经伤椎6钉固定组在旋转方向上的ROM小,差异有显著性(P<0.05).结论:经伤椎椎弓根置钉短节段钉棒固定可提高骨折模型各个运动方向上的生物力学稳定性,附加横连经伤椎6钉固定技术较单纯经伤椎6钉固定技术在轴向旋转运动方向上可提供更强的力学稳定性.     

腰椎三角固定装置的三维有限元分析

[目的]研究三角固定装置的生物力学特性,并与常规椎弓根螺钉固定方法比较.[方法]建立L3～5 TLIF三维有限元模型,分别用双侧椎弓根螺钉固定(BPSF)、单侧椎弓根螺钉固定(UPSF)、三角固定装置固定(TCF).L3表面施加500 N预载荷,再施加10N·m的力距模拟腰椎前屈、后伸、左右侧屈、轴向旋转等生理活动,测试不同工况下L4～L5节段角位移,椎弓根螺钉或经椎板关节突螺钉、融合器应力分布情况.[结果] BPSF与TCF L4～L5节段角位移小于UPSF; UPSF的螺钉应力峰值明显高于BPSF、TCF; UPSF椎间融合器的应力峰值在各种工况下高于BPSF、TCF,BPSF与TCF基本相似.[结论]TCF生物力学稳定性优于UPSF,与BPSF相似.     

单枚椎间融合器并对侧经皮椎弓根螺钉固定的生物力学研究

目的对单枚融合器联合单侧钉棒系统固定的生物力学性能进行评价。方法5具新鲜小牛腰椎标本，建立以下力学模型：A组：双侧开窗＋双枚融合器置入＋双侧椎弓根钉棒固定；B组：单侧小关节切除＋单枚融合器斜向置入＋同侧椎弓根钉棒固定；C组：单侧开窗＋单枚融合器置入＋同侧椎弓根钉棒固定；D组：单侧开窗＋单枚融合器置入＋对侧椎弓根钉棒固定。在生物力学平台上测试各试验组在不同工况下的ROM值。结果A组的固定最稳固，各工况下ROM值最低。B组的前后抗弯ROM值与A组差异无显著性，其左右侧弯和旋转方向的稳定性较A组有所降低。与B组比较，D组的前后弯曲性能与B组差异无显著性，其左右侧弯方向的ROM低与B组。两组的抗旋转ROM值差异无显著性。C组的左右抗弯及抗旋转性能均差于B、D组。结论单枚椎间融合器联合对侧椎弓根钉棒固定是一种力学性能较为优良组合，可以替代单侧斜向融合器并同侧椎弓根钉棒技术用于下腰椎微创手术。     

腰椎横突间入路椎体间融合术的生物力学评价

目的 观察腰椎横突间入路椎体间融合术(ILIF)及附加椎弓根钉固定后的生物力学稳定性.方法 采用小牛脊柱运动节段标本12具,依序进行不同处理后分为以下7组:(1)正常对照组(IS);(2)左侧小关节切除+椎间融合器植入组(TLIF);(3)TLIF附加同侧椎弓根钉固定组;(4)TLIF附加双侧椎弓根钉固定组;(5)左侧横突间入路椎间融合器植入组(ILIF);(6)ILIF附加同侧椎弓根钉固定组;(7)ILIF附加双侧椎弓根钉固定组.分别测试各组在轴向压缩、前屈、后伸、左右侧屈时的载荷-应变、载荷-位移变化以及轴向刚度和双向扭转稳定性等生物力学指标,并进行统计学比较.结果 所有生物力学指标中ILIF组稳定性均大于TLIF组(P<0.05),在定量扭矩扭角方面差距最大达72%.ILIF+BPSF的稳定性最高,在前屈载荷应变方面较IS组差异最大达53%,而ILIF+HPSF组与ILIF+BPSF组比较差异无统计学意义(P>0.05). 结论 ILIF手术生物力学稳定性优于TLIF手术;ILIF附加同侧椎弓根钉固定与附加双侧椎弓根钉固定生物力学稳定性相当,使用ILIF术式附加侧同椎弓根螺钉固定,可提供较好的即刻稳定性.     

前路腰椎椎间融合术即刻稳定性的生物力学研究

目的 评价应用聚醚醚酮(poly-ether-ether-ketone,PEEK)椎间融合器行前路腰椎椎间融合的即刻生物力学稳定性.方法 采用6具成人尸体腰椎标本,均来源于男性,X线榆查排除腰椎疾患和明显退行性改变,双能X线骨密度检查证实所有标本骨密度均处于正常范围.截取L4～S2节段腰椎,用自凝型聚甲基丙烯酸甲酯将标本两端固定在夹具内.沿腰椎轴线加载500N的预负荷后,分别在生物力学试验机上检测以下三种状态的前屈、后伸及侧屈各方向活动的即刻稳定性:完整腰椎标本,L5S1椎间盘切除、PEEK椎间融合器植入,辅以后路椎弓根螺钉系统固定.结果 L5S1椎间单纯椎间融合器植入后前屈、后伸、左侧屈方向的活动范围较完整腰椎标本分别减少76.9%、66.6%与81.1%;辅以后路惟弓根螺钉系统固定后,前屈、后伸、左侧屈方向的活动范围较完整腰椎标本分别减少93.9%、90%与86.6%.完整腰椎标本的空白对照组L4,5椎间前屈、后伸与左侧屈活动度分别为4.16°±0.33°、4.02°±0.30°、3.48°±0.34.;L5S1单纯椎间融合器组则分别为5.82°±0.36°、5.38°±0.30°、4.96°±0.29°;L5S1椎间融合器辅助椎弓根螺钉固定组则分别为4.82°±0.26°、5.76°±0.31°、3.98°±0.29°.L5S1椎间单纯椎间融合器植入及附加椎弓根螺钉崮定后,L4,5椎间相对活动度显著增加,各组间差异有统计学意义(P=0.000).结论 单纯应用PEEK椎间融合器的前路腰椎椎间融合术即刻稳定性优于完整腰椎标本.辅以后路椎弓根螺钉系统固定后融合节段稳定性得到显著增强.     

Spinal fusion: A combined anterior and supplementary interspinous technique

Standard, noninstrumented, techniques of anterior interbody fusion are frequently followed by nonunion and collapse of the intervertebral space, probably because of persistent rocking movements, particularly in the sagittal plane. Elimination of these theoretical movements by supplementing an anterior interbody fusion with a posterior interspinous H-graft and a cerclage wire was considered to be biomechanically attractive without having the disadvantages associated with posterior instrumentation. In a prospective study a solid fusion was obtained at 16 of 17 operated levels, with a mediocre (± 50%) fusion as the exception. The height of the intervertebral space was increased at the majority of the fused levels. The technique is only applicable where neural arches are intact. The technique proved to be safe, simple, effective and inexpensive.     

A systematic review with meta-analysis of posterior interbody fusion versus posterolateral fusion in lumbar spondylolisthesis

Purpose

To compare the clinical effectiveness of posterior lumbar interbody fusion (PLIF) and posterolateral fusion (PLF) for lumbar spondylolisthesis and to collect scientific evidence for determining which fusion method is better.

Methods

After systematic search, comparative studies were selected according to eligibility criteria. Checklists by Furlan and by Cowley were used to evaluate the risk of bias of the included randomized controlled trials (RCTs) and nonrandomized controlled studies, respectively. Weighed mean differences (WMDs) and risk differences were calculated for common outcomes. The final strength of evidence was expressed as different levels recommended by the GRADE Working Group.

Results

Four RCTs and five comparative observational studies were identified. Moderate-quality evidence indicated that PLIF was more effective than PLF for clinical satisfaction [odds ratios (OR) 0.49, 95 % confidence limits (95 % CI): (0.28, 0.88, P = 0.02)]. Moderate-quality evidence showed that no significant difference was found for the complication rate [OR 2.28, 95 % CI (0.97, 5.35), P = 0.06]. In secondary outcomes, moderate-quality evidence indicated that PLIF improved fusion rate [OR 0.32, 95 % CI (0.17, 0.61), P = 0.0006]. Low-quality evidence showed that PLIF resulted in a lower reoperation rate than PLF [OR 5.30, 95 % CI (1.47, 19.11), P = 0.01]. No statistical difference was found between the two groups with regard to blood loss [WMD = 76.52, 95 % CI (−310.68, 463.73), P = 0.70] and operating time [WMD = −1.20, 95 % CI (−40.36, 37.97), P = 0.95].

Conclusions

Moderate-quality evidence indicates that PLIF can improve the clinical satisfaction and increase the fusion rate compared to PLF. No superiority was found between the two fusion methods in terms of complication rate, amount of blood loss, and operating time for the treatment of lumbar spondylolisthesis.     

Transforaminal lumbar interbody fusion: a safe technique with satisfactory three to five year results

The unilateral transforaminal approach for lumbar interbody fusion as an alternative to the anterior (ALIF) and traditional posterior lumbar interbody fusion (PLIF) combined with pedicle screw instrumentation is gaining in popularity. At present, a prospective study using a standardized tool for outcome measurement after the transforaminal lumber interbody fusion (TLIF) with a follow-up of at least 3 years is not available in the current literature, although there have been reports on specific complications and cost efficiency. Therefore, a study of TLIF was undertaken. Fifty-two consecutive patients with a minimum follow-up of 3 years were included, with the mean follow-up being 46 months (36–64). The indications were 22 isthmic spondylolistheses and 30 degenerative disorders of the lumbar spine. Thirty-nine cases were one-level, 11 cases were two-level, and two cases were three-level fusions. The pain and disability status was prospectively evaluated by the Oswestry disability index (ODI) and a visual analog scale (VAS). The status of bony fusion was evaluated by an independent radiologist using anterior–posterior and lateral radiographs. The operation time averaged 173 min for one-level and 238 min for multiple-level fusions. Average blood loss was 485 ml for one-level and 560 ml for multiple-level fusions. There were four serious complications registered: a deep infection, a persistent radiculopathy, a symptomatic contralateral disc herniation and a pseudarthrosis with loosening of the implants. Overall, the pain relief in the VAS and the reduction of the ODI was significant (P<0.05) at follow-up. The fusion rate was 89%. At the latest follow-up, significant differences of the ODI were neither found between isthmic spondylolistheses and degenerative diseases, nor between one- and multiple-level fusions. In conclusion, the TLIF technique has comparable results to other interbody fusions, such as the PLIF and ALIF techniques. The potential advantages of the TLIF technique include avoidance of the anterior approach and reduction of the approach related posterior trauma to the spinal canal.     

The influence of intervertebral disc tissue on anterior spinal interbody fusion: an experimental study on pigs

Intervertebral disc has been shown to be related to low back pain and nerve root injury in pathologic conditions. However, little is known about its influence on spinal fusion. With the development of minimal invasive operations, such as laparoscopic anterior spinal fusion with cages, insufficient discectomy may occur. With its inflammatory properties, the residue nucleus pulposus may have an effect on spinal fusion. In this study, a two-level lumbar spine interbody fusion (L3/4, L5/6) with a Brantigan cage was performed on ten Danish Landrace pigs. Each level was randomly assigned to one of the following methods: (1) implantation of Brantigan cage filled with autogenous iliac crest bone graft, or (2) implantation of Brantigan cage filled with a mixture of autograft and the nucleus pulposus tissue harvested from the disc level in which it was to be inserted. Each level was stabilized with two staples. The pigs were followed for 12 weeks in the same standardized condition. After sacrifice, the lumbar spines were taken out, and plain X-ray, computed tomographic (CT) scanning and histomorphometry were performed to study the fusion mass inside the cages. From plain radiographs, new bone formation could be seen inside and around the cage. CT evaluation showed that the nucleus pulposus level had a 20% (2/10) fusion rate, while the pure autograft level had a 70% (7/10) fusion rate ( P=0.07). The histological fusion rate was even lower in the nucleus pulposus level (10%), and was significantly different from the autograft level (70%, P=0.02). Histomorphometric parameters of new bone formation, bone marrow space and fibrous tissue differed significantly between the two levels ( P=0.04; P=0.02; P=0.04 respectively). We conclude that when nucleus pulposus is mixed with the autogenous bone graft, it can delay or decrease the bone formation inside the cage, thus influencing the final fusion.     

斜外侧腰椎体间融合术初次术后邻近节段退变

[目的]评价斜外侧腰椎体间融合术(oblique lumbar interbody fusion,0LIF)治疗腰椎融合术后邻近节段退变的临床效果。[方法]回顾性分析2016年12月一2019年12月本院脊柱外科采用0LIF术治疗腰椎融合术后邻近节段退变50例患者的临床资料。[结果]50例患者均顺利完成手术,均未发生严重并发症。所有患者随访12?16个月,平均(13.74±1.63)个月。术后(12.66±3.64)周患者恢复完全负重活动。随访期间,患者术后疼痛逐步减缓,功能逐步改善。与术前相比较,末次随访时VAS和0DI评分均显著下降(P<0.05)。影像方面,与术前相比,末次随访时患者的腰椎前凸角(LL)显著增加(P<0.05),而侧凸Cobb角显著减少(P<0.05)。至末次随访时,50例患者再次手术椎间隙均达到骨性融合,椎间融合器无移位、下沉。[结论]采用0LIF治疗腰椎融合术后邻近节段退变具有较好的安全性和有效性。     

PLF与PLIF治疗峡部裂性腰椎滑脱的疗效比较

目的对比研究后外侧融合(posterolateral fusion,PLF)与后路椎间融合(posterior lumbar interbody fusion,PLIF)治疗Ⅰ～Ⅱ度峡部裂性腰椎滑脱的疗效。方法76例采取植骨融合附加椎弓根内固定的手术方法,33例采用后外侧融合,其余采用椎间融合,比较两种植骨方式术后植骨融合率和临床症状改善情况。结果临床优良率分别为81．82％和88．37％,两者无显著性差异(P>0．05);骨融合率分别为75．76％和90．7％,两者有显著性差异(P<0．05)。结论后外侧融合与椎间融合治疗Ⅰ～Ⅱ度峡部裂性腰椎滑脱的疗效相似,无明显差别。