腰椎椎间孔外椎体间融合术的生物力学分析

Biomechanical analyses of extraforaminal lumbar interbody fusion

目的利用生物力学的方法比较传统经椎间孔腰椎椎体间融合术(transforaminal lumbar interbody fusion,TLIF)与椎间孔外腰椎椎体间融合术(extraforaminal lumbar interbody fusion,ELIF),在不同内固定方式下的稳定性。方法选取12具新鲜尸体腰椎(L_3~S_1)标本,以聚甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)包埋。标本首先进行前屈后伸、左右侧屈及左右旋转的生物力学测试,数据取平均值,作为对照组,记为C组。随后将12具标本随机分为两组:T组(TLIF组)和E组(ELIF组),每组6例,各组再序贯分为3个亚组记为T1、T2、T3组及E1、E2、E3组。各组内固定方式如下:单边固定TLIF(T1组),单边固定ELIF(E1组),双边固定TLIF(T2组),双边固定ELIF(E2组),单边固定TLIF+对侧经椎板关节突螺钉内固定(T3组),单边固定ELIF+对侧经椎板关节突螺钉内固定(E3组)。采用Panjabi内固定物稳定性试验法进行生物力学测试,计算腰椎前屈、后伸、左右侧屈及左右旋转6种工况下的L4~L5节段角位移。结果 E1与T1组L4~L5活动度均较C组明显减小(P<0.05)。E1组各工况下的活动度小于T1组,尤以后伸、左侧屈、左旋及右旋时明显(P<0.05);E1组在各工况下的活动度明显高于T2组(P<0.05);E3组活动度除在右屈时活动度与E1组差异无统计学意义(P>0.05),其余各工况下活动度E3组均明显低于E1组(P<0.05),而且在限定载荷范围内与T2组之间差异无统计学意义(P>0.05),在当前载荷下E2组活动度与T2组活动度差异无统计学意义(P>0.05),E3组活动度与T3组活动度差异无统计学意义(P>0.05)。结论 ELIF单边固定的稳定性优于TLIF单边固定,但其稳定性低于经典的TLIF双边固定,ELIF手术单边固定加用对侧经椎板关节突螺钉固定后稳定性得以提高,在限定载荷范围内与TLIF双侧椎弓根螺钉固定相当,ELIF是一种安全有效,更加微创的腰椎椎体间融合术式。

Objective A biomechanics analysis was performed to evaluate the stability of traditionaltransforaminal lumbar interbody fusion （ TLIF） and extraforaminal lumbar interbody fusion （ ELIF）under different internal fixation. Methods Twelve fresh cadaveric lumbar spine specimens（ L3 .S1 ）were harvested and embedded in polymethylmethacrylate （ PMMA）. All specimens were tested inflexion, extension, lateral bending as well as the rotation. The mean value of all the data was recordedas the control group （C）. All specimens were divided into two groups as group T and group E, eachwas further divided as three subgroups （T1, T2 and T3; E1, E2 and E3）. The specimens were treatedas follows： unilateral fixation TLIF in group T1,unilateral fixation ELIF in group E1, bilateral fixation TLIF in group T2, bilateral fixation ELIF in group E2, unilateral fixation TLIF combined withcontralateral translaminar facet screw in group T3, unilateral fixation ELIF combined with contralateraltranslaminar facet screw in group E3. The angular variations of L4 .L5 were calculated in flexion,extension,lateral flexion and rotation movement using the internal fixation stability method reported byPanjabi. Results The range of motion （ROM） of groups E1 and T1 was significantly lower than that ofcontrol group. The ROM of group E1 was lower than that of group T1, especially in extension,leftbending,left rotation and right rotation. The ROM of E1 was significantly higher than that of group T2.The ROM of E3 was significantly decreased compared with E1 except in right bending. There was nosignificant difference in the ROM between groups E3 and T2. Under the current load, there was nosignificant difference in the ROM between groups T2 and E2, and between T3 and E3. Conclusion Thestability of unilateral fixation ELIF is superior to that of unilateral fixation TLIF, but is lower than that ofbilateral fixation TLIF. The stability of unilateral fixation ELIF will be improved by use of contralateraltranslaminar facet screw. ELIF is a safe and more efficient and less invasive operation approach.