Malakoutian Masoud, Street John, Wilke Hans-Joachim, Stavness Ian, Dvorak Marcel, Fels Sidney, Oxland Thomas
Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, Canada.
Department of Orthopaedics, University of British Columbia, ICORD, Blusson Spinal Cord Centre, 5th Floor, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
Eur Spine J. 2016 Sep;25(9):2929-37. doi: 10.1007/s00586-016-4686-y. Epub 2016 Jul 27.
It is well established that posterior spinal surgery results in damage to the paraspinal musculature. The effects of such iatrogenic changes on spinal loading have not been previously investigated, particularly at levels adjacent to a spinal fusion. Therefore, the objective of this study was to investigate the effect of simulated muscle damage on post-operative spinal loading at the adjacent levels to a spinal fusion during upright postures using a mathematical model.
A musculoskeletal model of the spine using ArtiSynth with 210 muscle fascicles was used to predict spinal loading in an upright posture. The loading at L1-L2 and L5-S1 were estimated before and after simulated paraspinal muscle damage (i.e., removal of muscle attachments at L2-L5) along the lumbar spine, both with a spinal fusion at L2-L5 and without a spinal fusion.
The axial compressive forces at the adjacent levels increased after simulated muscle damage, with the largest changes being at the rostral level (78 % increase in presence of spinal fusion; 73 % increase without spinal fusion) compared to the caudal level (41 % in presence of fusion and 32 % without fusion). Shear forces increased in a similar manner at both the rostral and caudal levels. These changes in loading were due to a redistribution of muscle activity from the local lumbar to the global spinal musculature.
The results suggest that the paraspinal muscles of the lumbar spine play an important role in adjacent segment loading of a spinal fusion, independent of the presence of rigid spinal instrumentation.
后路脊柱手术会导致椎旁肌肉组织受损，这一点已得到充分证实。此前尚未研究过这种医源性改变对脊柱负荷的影响，尤其是在脊柱融合相邻节段。因此，本研究的目的是使用数学模型，研究模拟肌肉损伤对脊柱融合相邻节段在直立姿势下术后脊柱负荷的影响。
使用带有210个肌束的ArtiSynth脊柱肌肉骨骼模型来预测直立姿势下的脊柱负荷。在腰椎模拟椎旁肌肉损伤（即去除L2-L5的肌肉附着点）前后，估计L1-L2和L5-S1的负荷，分别为L2-L5有脊柱融合和无脊柱融合的情况。
模拟肌肉损伤后，相邻节段的轴向压缩力增加，与尾侧节段（融合时增加41%，未融合时增加32%）相比，头侧节段的变化最大（融合时增加78%；未融合时增加73%）。头侧和尾侧节段的剪切力以类似方式增加。这些负荷变化是由于肌肉活动从局部腰椎肌肉重新分布到整体脊柱肌肉。
结果表明，腰椎的椎旁肌肉在脊柱融合的相邻节段负荷中起重要作用，与是否存在刚性脊柱内固定无关。
