单枚腰椎间融合器附加椎弓根螺钉行后路腰椎椎体间融合术的生物力学评价

目的 :探讨腰椎椎体间后路植入单枚融合器及附加椎弓根螺钉固定后的生物力学稳定性。方法 :采用 6具小牛腰椎标本 ,依序进行不同处理后分为以下 6组 :(1 )正常组 ;(2 )左侧小关节突加椎间盘切除组 ;(3)腰椎左侧融合器植入组 (椎体后路斜向植入 ) ;(4 )腰椎左侧融合器植入附加对侧椎弓根螺钉固定组 ;(5 )腰椎左侧融合器植入附加同侧椎弓根螺钉固定组 ;(6 )腰椎左侧融合器植入附加双侧椎弓根螺钉固定组。用实验应力分析方法 ,对单枚腰椎融合器植入附加椎弓根螺钉固定行后路腰椎椎体间融合术后 ,腰椎的即刻生物力学指标进行测定 ,并进行比较。 结果 :腰椎椎间盘摘除与小关节突切除后 ,其平均应力强度和轴向刚度均较正常标本显著下降 (P<0 .0 5 ) ;采用单枚融合器斜向植入椎间后 ,腰椎的平均应力强度和轴向刚度均较损伤标本 (椎间盘摘除与小关节突切除 )显著提高 (P<0 .0 5 ) ,但仍低于正常标本 (P<0 .0 5 ) ;采用椎间融合器植入附加同侧、对侧或双侧椎弓根螺钉内固定后 ,腰椎的平均应力强度和轴向刚度均较损伤标本和正常标本显著提高 (P<0 .0 5 )。结论 :斜向植入单枚腰椎间融合器行腰椎椎体间融合术 ,再附加椎弓根螺钉内固定 ,其生物力学性能优良 ,强度和刚度适中 ,腰椎能得到可靠的稳定性

Posterior lumbar interbody fusion using single anatomical threaded cage with transpedicular screw rod fixation:biomechanical study

Objective:To assess the relative stability and kinematics of the lumbar intervertebral segmental stiffness among posterior lumbar interbody fusion(PLIF) using one anatomical posterolateral cage with or without transpedicular screw rod fixation. Methods: Each of the 6 bovine lumbar functional spinal units(FSV) was tested under 6 different treatments. Test order was intact and every group differed in internal fixation of transpedicular screw. Group 1 referred to the normal lumbar functional spinal units. Group 2 was treated by left unilateral facetectomy and discoidectomy. Group 3 had anatomical threaded cages inserted on the left. Group 4 had anatomical threaded cages inserted on the left and fixed by right transpedicular screws. Group 5 had left inserted anatomical threaded cages and was fixed by left transpedicular screws. Group 6 had anatomical threaded cages inserted on the left side and was fixed by bilateral transpedicular screws. Nondestructive tests were performed in pure compression, flexion, extension, and lateral bending. Results: Unilateral discectomy and facetectomy had lower stiffness than normal FSU by 69% and 44% in pure compression, flexion, extension, and lateral bending. Single anatomical posterolateral cage group had higher stiffness than discectomy and facetectomy group, up by 55% and 28%. However, its stiffness was lower than normal FSU by 41% and 23%. Single anatomical cage with unilateral transpedicular screw fixation (left or right) had higher stiffness than normal FSU by 15% 17% and 20% 50% respectively. Single anatomical cage with transpedicular screw fixation was much stiffer than normal FSU by 18% and 65%. Conclusion: Adequate postoperative stability can be achieved by posterior lumbar interbody fusion with insertion of a single anatomical cage combined with a transpedicular screw.