三维有限元法分析不同骨密度对单纯斜外侧腰椎椎间融合后融合器下沉的影响

Influence of different bone mineral densities on cage subsidence after stand-alone oblique lateral interbody fusion:three-dimensional finite element analysis

背景:单纯斜外侧腰椎椎间融合的临床应用受患者骨密度影响较大,但该手术适应的骨密度目前国内外均无相关研究的报道。目的:比较不同骨密度下单纯斜外侧腰椎椎间融合模型的生物力学性能。方法:以健康成年男性志愿者的CT数据为基础,建立L_(3)-S_(1)正常对照有限元模型(M0组)、正常骨密度(T值>-1.0 SD)L_(4-5)单纯斜外侧腰椎椎间融合有限元模型(M1组)、骨量减少(-2.5 SD<T值<-1.0 SD)L_(4-5)单纯斜外侧腰椎椎间融合有限元模型(M2组)和骨质疏松(T值≤-2.5 SD)L_(4-5)单纯斜外侧腰椎椎间融合有限元模型(M3组)。在L_(3)椎体表面施加运动力矩10 N•m来模拟人体6种工况下的腰椎生物力学特性,评估L_(4-5)节段的运动范围及骨性终板和Cage应力分布情况。结果与结论:①相同工况下,与M0组相比,M1、M2和M3组L_(4-5)节段活动度均减少,其中以M3组减少幅度最大;②在前屈、后伸、左右侧弯工况下,与M0组比较,M1、M2、M3组骨性应力均明显增加;在左右旋转工况下,与M0组比较,M1、M2、M3组骨性终板应力不同程度的增加;相同工况下与M1组比较,M2组骨性终板应力降低不明显,M3组骨性终板应力增加明显;③相同工况下与M1组比较,M2组Cage应力降低不明显,M3组Cage应力增加明显;④结果提示,骨质疏松患者进行单纯斜外侧腰椎椎间融合手术存在Cage下沉的风险,对于骨密度T值>-2.5 SD的患者行单纯斜外侧腰椎椎间融合手术可以改善生物力学稳定性。

BACKGROUND:The clinical application of stand-alone oblique lateral interbody fusion is greatly affected by the bone mineral density of patients,but there is no relevant report on the specific bone mineral density at home and abroad.OBJECTIVE:To compare the biomechanical performance of an oblique lateral interbody fusion cage among different bone density models.METHODS:Based on the CT data of healthy adult male volunteers,there were L_(3)-S_(1) normal control finite element model(M0 group),the normal bone mineral density(T value>-1.0 SD)L_(4-5) stand-alone oblique lateral interbody fusion finite element model(M1 group),osteopenia(-2.5 SD<T value<-1.0 SD)L_(4-5) standalone oblique lateral interbody fusion finite element model(M2 group)and osteoporosis(T value≤-2.5 SD)L_(4-5) stand-alone oblique lateral interbody fusion finite element model(M3 group).A motion torque of 10 N•m was applied on the surface of the L3 vertebra to simulate the biomechanical properties of the lumbar spine under six working conditions of the human body and to evaluate the range of motion of the L_(4-5) segments and the stress distribution of the bony endplate and cage.RESULTS AND CONCLUSION:(1)Under the same working conditions,compared with the M0 group,range of motion of the L_(4-5) segments of the M1,M2,and M3 groups all decreased,and the M3 group had the largest reduction.(2)Under the conditions of flexion,extension,and lateral bending,compared with the M0 group,the bony stress of the M1,M2,and M3 groups all increased significantly.Under the left and right rotation,compared with the M0 group,the bony endplate stress of the M1,M2,and M3 groups increased to different degrees.Under the same conditions,compared with the M1 group,the bony endplate stress in the M2 group was not significantly decreased,and the bony endplate stress in the M3 group was significantly increased.(3)Compared with the M1 group under the same working conditions,the cage stress in the M2 group was not significantly decreased,and the cage stress in the M3 group was increased significantly.(4)The results suggest that there is a risk of cage subsidence in patients with osteoporosis who undergo stand-alone oblique lateral interbody fusion surgery.For patients with bone mineral density T value>-2.5 SD,stand-alone oblique lateral interbody fusion surgery can improve biomechanical stability.