步态仿真下腰椎间盘退变合并骶髂关节紊乱的有限元分析

目的通过观察腰椎间盘退变合并骶髂关节紊乱的生物力学特征,探讨腰椎间盘退变与骶髂关节紊乱相关性的生物力学机制。方法选取正常志愿者1名,腰椎间盘突出症合并骶髂关节紊乱者2名(骶骨错位、髂骨错位各1名),采集CT数据建立相应的正常、骶骨错位、髂骨错位腰椎-骨盆模型,同时采集其步态数据驱动Any Body仿真肌骨模型,得到腰椎骨盆周围肌肉力及髋关节力作为加载条件,进行有限元分析。比较患者与正常志愿者L4、L5椎间盘及骶髂关节应力变化。结果正常模型L4、L5左右及两侧骶髂关节应力曲线呈双峰,且无明显差异;骶骨错位模型与髂骨错位模型L4、L5左右及两侧骶髂关节应力曲线双峰改变甚至消失,L4左右两侧应力峰值差分别为0.55、0.80 MPa,L5左右两侧应力峰值差分别为4.05、2.08 MPa,骶髂关节右侧应力峰值与左侧峰值差分别为0.96、3.32 MPa。结论腰椎间盘退变合并骶髂关节错位导致人体承重力线的偏移,骶髂关节紊乱可加重身体两侧应力失衡,在腰椎间盘突出症的治疗过程不能忽视骶髂关节紊乱的影响。

Finite element analysis of lumbar disc degeneration with sacroiliac joint disorder by gait simulation

Objective To explore the biomechanical mechanisms of correlation between lumbar disc degeneration and sacroiliac joint disorder though investigating the biomechanical characteristics of lumbar disc degeneration with sacroiliac joint disorders. Methods One normal healthy volunteer and two patients with lumbar disc herniation and sacroiliac joint disorders (one was with sacrum disorders and the other was ilium disorders) were selected. Their CT data were collected to establish three corresponding lumbar-pelvis finite-element models, and their gait data were also simultaneously collected to drive the AnyBody musculoskeletal model. The muscle force around the lumbar and pelvis as well as the hip joint force were acquired as loading condition for finite element analysis. The stress changes in L4 and L5 intervertebral discs and sacroiliac joints of the patients and normal volunteer were compared. Results There was no significant difference in the stress of the two sides of L4, L5 disc and two sacroiliac joints in normal model, with a bimodal stress curve. However, in the models of sacrum disorders and ilium disorders, the bimodal stress curve peaks changed, even disappeared. The peak stress differences in left and right side of L4 disc were 0.55 MPa and 0.80 MPa, respectively, the peak stress differences in left and right side of L5 disc were 4.05 MPa and 2.08 MPa, respectively, and the peak stress differences in left and right side of sacroiliac joints were 0.96 MPa and 3.32 MPa, respectively. Conclusions The lumbar disc degeneration with sacroiliac joint disorder leads to the tilt of the body loading line, and sacroiliac joint disorder can aggravate the imbalances of stress on the body sides. The impact of sacroiliac joint dysfunction cannot be ignored in the treatment of lumbar disc herniation.