动态磁共振成像参数与腰椎不稳的关系

目的:探讨腰椎不稳与脊柱功能单元中的动态磁共振成像参数(椎间盘退变、小关节骨关节炎及黄韧带肥厚)之间关系。方法:按Kong的标准诊断为腰椎不稳患者79例(237个脊柱功能单元),采用动态MRI在患者中立及过屈、过伸3个体位成像。测定L3/L4、L4/L5及L5/S1椎间盘退变(Ⅰ～Ⅴ级)、小关节骨关节炎(1～4级)、黄韧带肥厚(>3mm为黄韧带肥厚阳性)参数,评估其与腰椎不稳的相关性。结果:L4/L5节段不稳(36个)的发生较L3/L4(18个)及L5/S1节段多(25个)。椎间盘退变、小关节骨关节炎以及黄韧带肥厚(+)均与L3/L4、L4/L5、L5/S1 3个节段腰椎不稳相关(P<0.05)。结论:Ⅳ级椎间盘退变、3级小关节骨关节炎及黄韧带肥厚(+)分别与腰椎不稳的形成有关,在诊断腰椎不稳时,动态MRI及其3个参数具有辅助诊断的作用。     

腰椎后路固定融合术后邻近节段退变的中期随访研究

目的随访观察腰椎后路融合内固定术后〉5年邻近节段椎间盘退行性变的程度,讨论其影响程度和因素。方法随访1999～2003年行腰椎后路融合术（L4/L5/S1、L5/S1）的患者33例,通过X线检查及部分病例的MRI检查,观察腰椎固定融合术后上方邻近节段（L3/L4、L4/S5）椎间盘退行性变的发生率和程度。结果腰椎固定融合术后邻近节段椎间盘退行性变的发生率为54.5%（18/33）,但邻近节段椎间隙高度降低和日本骨科学会（Japanese Orthopae-dic Association,JOA）评分之间没有明显关联。结论腰椎融合术后邻近节段椎间盘发生退行性变的比例较高,但退变和临床疗效间并没有明显联系。     

Modic改变在腰腿痛病例中的分布及相关因素分析

目的探讨腰椎终板Modic改变在腰腿痛病例中的的临床分布特点，并探讨发生Modic改变的相关因素。方法选择2005年一年内因腰痛或坐骨神经痛行腰椎MR检查和常规X线检查的患者1223例，分析腰椎MRI中终板Modic改变在椎间盘节段、年龄和椎间盘退变分类中的分布特点及其相关因素。结果1223例6115个腰椎椎间盘中，257例（21．0％）320个椎间盘（5．2％）邻近终板发生M0dic改变，其中Ⅰ型48例（3．9％）51个椎间盘（0．8％），Ⅱ型206例（16．8％）266个椎间盘（4．3％）、Ⅲ型3例（0．2％）3个椎间盘（0．05％）。椎间盘节段L5S1 168个、L4-5 95个、L3-4 29个、L2-3 18个、L1-2 10个，发生率分别为13．7％、7．8％、2．4％、1．5％、0．8％。突出、脱出和滑脱病例发生率较高（辟0．00）。女性发生率高于男性（P=0．005）。40岁以上是Modic改变发生较多的年龄段（P=0．001）。椎间盘退变程度、椎间盘节段与年龄均和Modic改变具有显著相关性（P=0．000）。回归方程为Y=-5．955＋0．198A＋1．528L＋1．883D（Y为M0dic改变，A为年龄，L为椎间盘节段，D为椎间盘退变程度），P=0．000，EXP值：D=6．571，L=4．609，A=1．220。结论腰椎终板Modic改变和椎间盘退变、椎间盘节段和年龄之间存在相关关系，椎间盘退变是最重要的影响因素。Modic改变Ⅱ型最多，Ⅰ型次之，Ⅲ型最少；多发生于L4-5和L5S1椎间盘节段；女性高于男性；40岁以上是易发年龄。     

退变性腰椎不稳固定节段与邻近节段椎间盘退变的关系

目的探讨后路减压、固定、融合术后治疗退变性腰椎不稳的疗效,固定后邻近节段椎间盘退变发生机率与相关性。方法回顾性分析2005年8月～2010年8月下腰椎固定术180例患者的临床资料。结果随访1～5年,其中有症状性退变2例,均为固定近端相邻的椎间盘,而且此阶段椎间盘术前均有不同程度的退变。结论退变性腰椎不稳固定治疗后出现邻近节段椎间盘退变与腰椎固定及固定阶段多少本身无关,与固定前邻近节段椎间盘有无退变关系明显,且多发生于固定节段近端。     

腰椎间盘退变性疾患下腰椎终板形态的MRI观察

【摘要】　目的：在MRI片上观察腰椎间盘退变患者下腰椎终板形态的分布规律,分析终板形态和椎间盘退变的关系。方法：回顾分析两组腰椎间盘退变性疾病患者的术前腰椎MRI,A组110例为单节段腰椎间盘突出症患者,B组35例为椎间盘源性腰痛患者。根据正中矢状面MRI T1像,将终板形态分为凹面、平坦、不规则三型;根据Pfirrmann法评定椎间盘退变程度并将Ⅰ～Ⅴ级分别计为1～5分;按Modic改变分级标准判定各节段终板有无Modic改变。分析下腰椎终板的形态特点及三种分型与椎间盘退变程度、Modic改变等的关系。结果：①435个下腰椎节段中,凹面型终板最多（215/435）,A组中占50.6％（167/330）,B组中占45.7％（48/105）,且主要分布于L3/4（108/215）、L4/5（83/215）节段;平坦型终板占29.0％（126/435）,并主要位于L5/S1节段（76/126）;不规则型终板最少（94/435）,A组中占23.0％（76/330）,B组中占17.1％（18/105）,也主要位于L5/S1节段（45/94）。②A组患者中,凹面型终板退变程度平均为3.31±0.81分,平坦型为3.66±0.64分,不规则型为4.16±0.67分,两两比较有显著差异（P＜0.05）;椎间盘突出节段以平坦型（37/110）和不规则型（43/110）终板占多数,无突出节段则以凹面型（137/220）终板占多数,差异有显著性（P＜0.05）;不规则型终板比凹面型和平坦型更容易伴发Modic改变,差异有显著性（P＜0.05）,凹面型和平坦型间无显著性差异（P＞0.05）。③B组患者中,凹面型终板的椎间盘退变程度平均为3.23±0.86分,平坦型为3.54±0.85分,不规则型为3.94±0.54分,仅凹面型和不规则型间差异有显著性（P＜0.05）。④相同终板形态时A组和B组椎间盘退变程度相比均无显著性差异（P＞0.05）。结论：终板形态与椎间盘退变、Modic改变之间有相关性。终板形态由凹面型到平坦型再到不规则型,腰椎间盘退变程度逐渐加重。影像学上终板形态改变在一定程度上反映了椎间盘退变的程度。     

我国汉族人腰椎骨密度与相邻椎间盘退变的相关性研究

目的研究并探讨腰椎骨密度和相邻椎间盘退变之间的相关关系。方法回顾性选取同时有腰椎磁共振和DXA腰椎骨密度检查的男性人群224例、女性人群288例。Pfirrmann法评估腰椎间盘退变程度,多因素回归统计分析腰椎骨密度与年龄、体重指数以及腰椎间盘退变的相关性。结果男性人群年龄显著小于女性人群(P0.01),而男性人群体重指数大于女性人群(P0.01);男性人群各节段腰椎骨密度均大于女性人群(P0.01),女性人群各节段腰椎间盘退变程度均大于男性人群(P0.01);下腰椎(L3、L4)的腰椎骨密度和腰椎间盘退变程度均比上腰椎高(L1、L2)。男性人群中,下腰椎L4椎体骨密度与相邻的L4/5椎间盘退变程度呈正性相关(Coef.=0.04,P0.05);女性人群中,下腰椎L3和L4椎体骨密度分别与相邻的L3/4、L4/5椎间盘退变程度呈正性相关(Coef.=0.04,P0.01);其余椎体骨密度与相邻椎间盘退变均未见统计学相关性。结论下腰椎椎体骨密度越大,相邻的椎间盘退变越严重。相对较高的腰椎骨密度可能是腰椎间盘退变的危险因素。     

退行性腰椎不稳发病相关因素的临床研究

目的分析性别、年龄、相应节段椎间盘退变、小关节突骨关节炎以及椎体滑脱与退行性腰椎不稳的相关性。方法行腰椎MRI及站立位过伸过屈侧位片检查,观察L1-S15个运动节段的椎间盘退变、椎间小关节退变以及有无椎体滑脱。腰椎不稳分为前水平位移不稳．后水平位移不稳和角度不稳。椎间盘退变分四度。小关节突退变分为4级。腰椎滑脱分四度。将结果进行Spearman等级相关分析。结果前向水平不稳与椎间盘退变呈正相关,与椎间小关节骨关节炎呈负相关,与椎体滑脱呈正相关;后向水平不稳与年龄呈正相关,与椎间盘退变呈正相关。与椎间小关节骨关节炎呈正相关,与椎体滑脱没有明显相关性。结论退行性腰椎不稳与多种因素具有显著相关性,但腰椎滑脱不一定有不稳。     

腰椎内固定融合术后邻近节段退变的影响因素

目的探讨腰椎内固定融合术后邻近节段退变的影响因素。方法对1998年3月至2002年5月33例行腰椎内固定融合术的病例进行随访研究,观察其术后邻近节段退变的发生率、发生年龄、部位、影像学特点以及临床表现,对是否“悬浮固定”、内固定融合范围、不同邻近节段退变的风险进行对比。结果33例患者随访34～82个月,平均4年7个月。发现影像学上有退变表现10例（占30．3％）,10例中有9例退变发生在头侧节段。发生邻近节段退变以60岁以上患者为主。是否进行“悬浮固定”对内固定融合术后邻近节段退变的影响无统计学差异。多节段融合术后较单节段融合术后邻近节段退变有增多的趋势。L2／L3作为邻近节段时退变风险较高,而L5／L1,作为邻近节段退变风险较低。结论头侧邻近节段较尾侧节段更容易发生退变。如果L2／L3可能作为邻近节段,术前有退变表现,术中需将其进行固定融合,而如果L5／S1在术前没有明显退变证据,则不需要将其进行固定融合。腰椎内固定融合时,尽量避免长节段固定融合。     

经皮激光腰椎间盘减压术后腰椎关节突关节和椎间高度的变化

目的：观察经皮激光椎间盘减压术（percutaneous laser disc decompression，PLDD）治疗腰椎间盘突出症术后腰椎关节突关节和椎间高度的变化。方法：应用半导体激光系统对32例腰椎间盘突出症患者进行PLDD治疗。29例患者为单节段突出，其中L3/4 3例，L4／5 18例，L5/S1 8例；3例患者同时合并IA／5和L5/S1节段突出。利用Macnab标准评价随访患者的疗效，并观察术前、术后椎间盘突出节段关节突关节角的形态，测量L3，4、L4/5和L5／S1椎间高度指数和椎间盘突出节段关节突关节角的角度。结果：所有患者无术中和术后并发症。随访14～22个月，平均17个月，按Macnab标准评价：优14例（43．75％），良13例（40．63％）；可3例（9．37％），差2例（6．25％），优良率84．38％。术后L5/S1椎间高度指数与术前相比显著性下降（P〈0．05），但L3/4和L4／5椎间高度指数无显著性改变；关节突关节无明显退变；L4／5和L5／S1椎间盘突出侧的关节突关节角角度显著性下降（P〈0．05），但L3/4椎间盘突出侧的关节突关节角度无显著性改变。结论：经皮激光腰椎间盘减压术后患者的L5／S1椎间高度和腰椎间盘突出侧关节突关节角角度下降．有可能增加腰椎滑脱的风险。     

腰椎小关节不对称与椎间盘变性

对54例年龄大部分在50岁以下、经保守治疗效果不明显的慢性腰痛患者，为进一步查明病因而作了CT扫描及MRI成像检查。应用CT扫描测量小关节角度并决定两侧小关节的对称性。用MRIT2加权像观察L3－4、L4-5和L5－S1水平的椎间盘有无变性。结果显示，由L3－4～L5－S1小关节角度逐渐增加。同一水平一侧小关节增大，即两侧小关节不对称与该节段的椎间盘变性有权明显的相关性。腰椎小关节不对称者，该节段椎间盘变性的发生率明显增加。作者认为，小关节不对称增加了椎间盘退变的危险性，可能是椎间盘早期发生退变的重要因素。     

Lumbar disc degeneration and segmental instability: a comparison of magnetic resonance images and plain radiographs of patients with low back pain

We analyzed disc space height, angular displacement, tilting movement, and horizontal displacement in 109 patients with low back pain and/or sciatica, on plain radiographs of the lumbar spine. These parameters were compared with the grade of disc degeneration as evaluated by magnetic resonance imaging with the aim of studying lumbar segmental instability. Disc space height decreased in proportion to the grade of disc degeneration. Angular displacement was significantly less with severe disc degeneration, accompanied by a tendency to stabilization of the motion segment. Tilting movement and horizontal displacement. did not correlate with the grade of disc degeneration. Lumbar segmental instability was recognized at all levels even in individuals who appeared to be normal or to have mild disc degeneration. The incidence of lumbar segmental instability at the L3-4 level was significantly higher in patients with normal discs or mild disc degeneration. At the L4-5 and L5-S levels it did not differ between different grades of disc degeneration.     

Rotational hypermobility of disc wedging using kinematic CT: preliminary study to investigate the instability of discs in degenerated scoliosis in the lumbar spine

The number of patients showing lumbar degenerative scoliosis, including disc wedging, has increased, and examination of the mechanism of spinal nerve compression due to lateral and rotational mobility of the lumbar spine is necessary. Thirty-two patients with L4–L5 disc wedging but without antero- or retrospondylolisthesis and ten age-matched controls were examined. The angle of disc wedging and change in the angle between left and right bending were evaluated by anterior–posterior X-ray images of patients while they were in a standing position. The degree of disc degeneration and existence of vacuum phenomena were evaluated at the L4–L5 discs. Rotational mobility between maximal right and left rotation was examined by computed tomography (CT). Rotational mobility was measured using the spinal transverse processes of L4 and L5. The relationship between these factors was statistically evaluated using multivariate analysis and Spearman’s correlation test. There was a significant increase in the average rotational mobility of the L4–L5 disc-wedging group. In the L4–L5 disc-wedging group, the increased angle of disc wedging and change in the angle between left and right bending correlated with increased rotational mobility. The degree of disc degeneration did not affect rotational mobility. However, existence of vacuum phenomena increased the rotational mobility of the L4–L5 disc-wedging group. This is the first study to evaluate the rotational hypermobility of L4–L5 disc wedging in patients without antero- or retrospondylolisthesis using kinematic CT. Increases in the wedging angle and abnormal instability of lateral bending correlated with increased rotational mobility. For surgical planning of degenerative L4–L5 disc wedging, it is important to consider rotational hypermobility using kinematic CT or X-ray imaging findings of lateral bending.     

合并椎间盘突出的退变性腰椎滑脱椎间盘形态改变及其意义

【摘要】 目的：观察合并椎间盘突出的退变性腰椎滑脱（lumbar degenerative spondylo-listhesis,LDS）患者的椎间盘影像学特点,探讨椎间盘退变程度、椎间隙角度及高度与退变性腰椎滑脱间的关系。方法：以2009年10月～2011年11月我院和石景山医院收治的合并L4/5椎间盘突出的退变性腰椎滑脱患者37例作为观察组,另选同期单纯L4/5椎间盘突出症患者38例作为对照组,对L4/5椎间盘退变程度按照Pfirrmann法分级,CT测定L4/5椎间盘正中矢状面的椎间隙角度和椎间隙高度,对所得数据进行统计分析。结果：观察组L4/5椎间盘MRI退变程度B、C、D、E级分别为1、25、8及1例,对照组分别为2、21、13及2例,两组椎间盘退变程度间差异没有显著性（P>0.05）;CT测量L4/5椎间隙角度观察组和对照组分别为3.08°±1.87°和6.48°±2.92°,对照组椎间隙角度明显大于观察组（P<0.05）;椎间隙高度观察组和对照组分别为8.46±1.81mm和9.38±2.46mm,两组间比较差异没有显著性（P>0.05）。结论：椎间隙角度减小,可能是退变性腰椎滑脱发病的重要因素之一。     

Disc degeneration in young patients with isthmic spondylolisthesis treated operatively or conservatively: A long-term follow-up

The purpose of this longterm follow-up was (1) to investigate disc changes in the olisthetic segment in patients treated conservatively, (2) to compare disc changes above the slipped vertebra in conservatively treated patients with those in operatively treated patients, and (3) to establish possible relations of disc changes to the degree of the slip and to subjective back pain symptoms of the patients. The subjects were 227 patients with isthmic L5 olisthesis diagnosed under 20 years of age (mean 13.8 years) with a mean follow-up of 15.4 (range 5–30) years. Of these, 145 patients had been treated with segmental fusion and 82 had been treated conservatively. At follow-up, standing anteroposterior and lateral radiographs as well as flexion/extension views of the lumbar spine were taken. Disc degeneration was graded semiquantitatively: 0 = normal disc height, 1 = decrease of disc height < 50%, 2 = decrease 50%, and 3 = obliteration of the disc. In the conservatively treated patients degeneration of the olisthetic disc was distributed by grade as follows: 0:n = 38, 1:n = 24, 2:n = 14, 3:n = 6. No motion at all was observed in the olisthetic segment in 40 patients (48%) with a mean slip of 30%,, segmental motion of 4°–18° was found in 42 patients with a mean slip of 14%. There was a statistically significant association of the degree of slip to the severity of disc degeneration and non-mobility of the segment. Grade 1 degeneration of the L4/5 disc occurred in 25.6% of the conservatively treated patients and in 32% of 48 patients treated with L5-S1 fusion. This correlated with the severity of the slip, but not with pain symptoms or pathologic segmental mobility at the time of follow-up. Out of 84 patients with L4-S1 fusion, in 17% grade 1 degeneration of the L3/4 disc was observed, and 3 out of 13 patients (23%) with L3-S1 fusion had grade 1 degeneration of the disc above the fusion. The disc changes had no correlation with subjective pain symptoms. It is concluded that the natural course of isthmic spondylolisthesis is associated with disc degeneration and spontaneous stabilization of the olisthetic segment. Fusion operations do not significantly increase the rate of disc degeneration in the adjacent disc above the fusion after a mean postoperative follow-up of 13.8 years. No correlation between the number of degenerated discs or the degree of degeneration and subjective low back pain symptoms was found.     

颈椎椎间盘退行性改变与颈椎不稳

探讨颈椎椎间盘退性改变与颈椎不稳定的关系。方法对２６０例怀疑有颈椎疾患的者行Ｘ线及ＭＲＩ检查。在颈椎屈曲／伸展侧位片上测量椎体水平位及成象程度,并根据ＭＲＩＴ２加权像椎间盘信号强度判断其退变程度。结论颈椎的节段性不稳定是颈椎椎间盘退行改变的早期表现之一。     

Do early stages of lumbar intervertebral disc degeneration really cause instability? Evaluation of an in vitro database

Early stages of intervertebral disc degeneration are postulated to cause instability. In the literature, however, some authors report the opposite. These contradictory positions are probably supported by the mostly small number of segments which are investigated. The aim of this project therefore was to investigate the influence of intervertebral disc degeneration on lumbar spine rotational stability using a large data set. The flexibility data from all spine specimens tested in our institute so far were collected in a large in vitro database. From this database, all lumbar spine specimens were selected, which had been tested for flexibility under pure moment loads of ±7.5 N m and for which radiographs were accessible. 203 segments met these criteria. Their radiographic degree of disc degeneration was determined on a scale from 0 (no degeneration) to 3 (severe degeneration) and their influence on the respective range of motion and neutral zone was examined. The different lumbar levels differ in flexibility, which increases the variability of the data if pooled together. To minimise this effect a statistical model was fitted. The model-based mean estimates showed a decrease of the range of motion from grade 0 to 3 in flexion/extension (by 3.1°, p < 0.05) and lateral bending (by 3.4°, p < 0.05). In contrast, in axial rotation the range of motion tended to increase; however, not only from grade 0 to 1 but also towards grade 3 (by 0.2°) (p > 0.05). The neutral zone was affected in a similar way but to a smaller degree (p > 0.05). In conclusion, the results indicated that early stages of intervertebral disc degeneration do not necessarily cause rotational instability. In contrast, stability increased in flexion/extension and lateral bending. Only in axial rotation stability tended to decrease.     

Non-fusion instrumentation of the lumbar spine with a hinged pedicle screw rod system: an in vitro experiment

In advanced stages of degenerative disease of the lumbar spine instrumented spondylodesis is still the golden standard treatment. However, in recent years dynamic stabilisation devices are being implanted to treat the segmental instability due to iatrogenic decompression or segmental degeneration. The purpose of the present study was to investigate the stabilising effect of a classical pedicle screw/rod combination, with a moveable hinge joint connection between the screw and rod allowing one degree of freedom (cosmicMIA). Six human lumbar spines (L2–5) were loaded in a spine tester with pure moments of ±7.5 Nm in lateral bending, flexion/extension and axial rotation. The range of motion (ROM) and the neutral zone were determined for the following states: (1) intact, (2) monosegmental dynamic instrumentation (L4-5), (3) bisegmental dynamic instrumentation (L3–5), (4) bisegmental decompression (L3–5), (5) bisegmental dynamic instrumentation (L3–5) and (6) bisegmental rigid instrumentation (L3–5). Compared to the intact, with monosegmental instrumentation (2) the ROM of the treated segment was reduced to 47, 40 and 77% in lateral bending, flexion/extension and axial rotation, respectively. Bisegmental dynamic instrumentation (3) further reduced the ROM in L4-5 compared to monosegmental instrumentation to 25% (lateral bending), 28% (flexion/extension) and 57% (axial rotation). Bisegmental surgical decompression (4) caused an increase in ROM in both segments (L3–4 and L4–5) to approximately 125% and approximately 135% and 187–234% in lateral bending, flexion/extension and axial rotation, respectively. Compared to the intact state, bisegmental dynamic instrumentation after surgical decompression reduced the ROM of the two-bridged segments to 29–35% in lateral bending and 33–38% in flexion/extension. In axial rotation, the ROM was in the range of the intact specimen (87–117%). A rigid instrumentation (6) further reduced the ROM of the two-bridged segments to 20–30, 23–27 and 50–68% in lateral bending, flexion/extension and axial rotation, respectively. The results of the present study showed that compared to the intact specimen the investigated hinged dynamic stabilisation device reduced the ROM after bisegmental decompression in lateral bending and flexion/extension. Following bisegmental decompression and the thereby caused large rotational instability the device is capable of restoring the motion in axial rotation back to values in the range of the intact motion segments.     

双节段后路腰椎椎体间融合术单侧椎弓根钉固定的生物力学稳定性

目的 分析对模拟双节段腰椎后路椎体间融合术(PLIF)采用单侧椎弓根钉固定(单侧固定)的生物力学稳定性.方法 将6具新鲜成人尸体腰椎标本(L2～S2)分别制备成L4～S1的PLIF模型,应用MTS 858实验机模拟产生屈伸、侧弯、轴向旋转,并按初始状态、单侧不稳、单侧不稳-单侧固定、双侧不稳-单侧固定、双侧不稳-双侧固定、双侧不稳的顺序进行测试,动态摄取记录各个节段角位移运动范围(ROM)与中性区值(NZ).结果 单侧不稳-单侧固定屈伸、侧弯、轴向旋转方向ROM值依次为2.53±1.12、4.03±2.19、2.78±1.00,NZ值依次为1.14±0.70、1.96±1.13、1.28±0.71,均显著小于初始状态(P<0.05),相比双侧不稳-双侧固定,各方向ROM与NZ值分别增加60.13%与17.52%、315.46%与243.86%、8.17%与6.20%,但差异无统计学意义(P>0.05).双侧不稳-单侧固定侧弯与旋转状态ROM与NZ值较双侧不稳-双侧固定显著增加(P<0.05).结论 单侧固定对人腰椎标本模拟双节段单侧PLIF可提供与双侧固定相似的生物力学稳定性,而对于模拟双节段双侧PLIF则单侧固定在大多数三维运动方向上不能提供足够的力学稳定性.

Abstract：

Objective To analyze the biomechanical efficacy of unilateral pedicle screw fixation on human cadaveric lumbar spine model simulated by two-level posterior lumbar interbody fusion (PLIF). Methods Six fresh-frozen adult human cadaveric lumbar spine motion segments (L2-S2) were simulated to unilateral/bilateral L4-S1 PLIF constructs augmented by unilateral/bilateral pedicle screw fixation sequentially and respectively. All configurations were tested by MTS 858 in the following sequential construct order: the intact, UI (unilateral instability), UIUF1C (unilateral instability via unilateral pedicle screw fixation plus one cage) , BIUF1C (bilateral instability via unilateral pedicle screw fixation plus one cage) , BIBF1C (bilateral instability via bilateral pedicle screw fixation plus one cage) and BI (bilateral instability without pedicle screw and cage). Each specimen was nondestructively tested in flexion/extension, lateral performed between different simulated constructs with One Way of ANOVA and Post hoc LSD tests. Results BIBF1C had the lowest ROM and NZ of L4-S1 fusion segments in all loading models, which were significantly lower than those of any uninstmmented construct (the intact, UI and BI) (P < 0. 05). In flexion/extension, lateral bending, and axial rotation, the ROM of UIUF1C was respectively 2.53 ± 1. 12, 4.03 ± 2. 19, 2. 78 ±1.00 and the NZ of UIUF1C was respectively 1.14 ±0.70, 1.96 ±1. 13, 1.28 ±0.71, which were significantly lower than those of the intact (P <0. 05). Compared to BIBF1C, the ROM and NZ were respectively increased 60.13% and 17.52% in flexion/extension, 315.46% and 243.86% in lateral bending, 8. 17% and 6. 20% in axial rotation, however, there were no significant differences between these two constructs (P > 0. 05). In lateral-bending and axial rotation, the ROM and NZ of BIUF1C were significantly higher than those of BIBF1C (P < 0. 05). In flexion/extension, the ROM and NZ of BIUF1C were higher than those of BIBF1C but there were no significant differences (P >0. 05). Compared to the intact, BIUF1C had lower ROM and NZ except for higher NZ in axial rotation, and there were significant differences only in flexion/extension (P < 0. 05). Conclusions All tested two-level unilateral fixation on simulated human cadaveric model with unilateral PLIF can achieve similar initial biomechanical stability in comparison with two-level bilateral pedicle screw fixation. However in most test modes, two-level unilateral pedicle screw fixation on simulated human cadaveric model with bilateral PLIF can not achieve enough biomechanical efficacy in comparison with two-level bilateral pedicle screw fixation.