脊柱三维运动对腰髓核摘除术后小关节的作用机制

目的观测髓核摘除术后腰椎小关节的应力分布变化。方法取新鲜青壮年尸体下腰椎标本6具,在L4下关节突、L5上下关节突、S1上关节突分别贴横形和竖形微细应变片进行力学测试。首先在髓核摘除前测量各应变片在轴向加压、前屈、后伸、侧屈、旋转工况下的应变值;然后在所有标本上行单侧L5/S1开窗髓核摘除术,在同样加载条件下测量应变值;最后在所有标本对侧行L5/S1开窗髓核摘除术形成双侧髓核摘除,重复加载测量应变值。结果轴向加压工况时3种实验力学状态应变量均无差异;前屈工况时L5下关节突竖形应变量髓核摘除前与双侧髓核摘除状态差异有统计学意义;后伸工况时L5上、下关节突竖形应变量双侧髓核摘除状态与其它2种实验力学状态相比差异均有统计学意义;侧屈工况时3种实验力学状态应变量均无差异;旋转工况时L4下关节突竖形片应变量髓核摘除前与单侧髓核摘除相比、单侧髓核摘除与双侧髓核摘除状态比较差异均有统计学意义,L5下关节突横行片应变量双侧髓核摘除状态与其它2种实验力学状态比较差异有统计学意义,S1上关节突竖形片应变量髓核摘除前与双侧髓核摘除状态比较差异有统计学意义。结论单侧开窗髓核摘除术后邻近关节突稳定性保存良好,但是双侧开窗髓核摘除术后下腰椎邻近节段关节突在前屈、后伸、旋转运动时与髓核摘除前比较应变量显著增高,稳定性下降,需要给予适当的稳定措施。

Biomechanics experiment in vitro on lumbar facet articular process after discectomy

Objective To investigate the biomechanics of lumbar facet joint after discectomy by strain gage′s measurement.Methods There were 6 cadaveric lumbar spine used in the experiment.The adjacent facet joints discectomy at L5/S1 including L4 inferior,L5 superior and inferior,S1 superior articular process were pasted by transverse and vertical micro-strain gages.Then the gages were measured under loading in three kinds of conditions（Pre-discectomy（PD）,Unilateral discectomy at L5/S1（UD）,Bilateral discectomy at L5/S1（BD））.At first,the strain gages of PD specimens were measured under loading in sequence of axial compression,flexion,extension,lateral bending and torsion.After the unilateral discectomy at L5/S1,all of specimens were measured under loading again.The third loading measurement was post-operation of bilateral discectomy at L5/S1.Results There were no significant difference among PD,UD and BD under axial compression and lateral bending loading.The significant difference was observed between PD and BL of vertical strain gages at L5 inferior articular process under flexion loading,PD or UD and BD of vertical strain gages at L5 superior and inferior articular process under extension loading,PD and UD,BD and UD of vertical strain gages at L4 inferior articular process,PD or UD and BD of transverse strain gages at L5 inferior articular process,PD and BD of vertical strain gages at S1 superior articular process under torsion loading.Conclusions The stability of adjacent facet joint can be maintained well after unilateral discectomy.However,the spine can be destabilized after bilateral discectomy at adjacent facet joint under flexion,extension and torsion loading.The latter lumbar spine needs appropriate surgery.