Matthews Phoebe G M, Cadman Joseph, Tomka Janos, Dabirrahmani Danè, Appleyard Richard, Kam Andrew
Faculty of Medicine and Health Sciences, Department of Biomedical Sciences, Biomechanics Research Group, 2 Technology Place, Macquarie University, NSW, Australia.
J Spine Surg. 2020 Mar;6(1):3-12. doi: 10.21037/jss.2020.01.15.
To assess whether lumbar pedicle screw placement with a minimally invasive surgical (MIS) open technique imparts different biomechanical parameters and thus may affect failure rates.
Human cadaveric disarticulated lumbar vertebrae 1-5 were stabilised in cement. Pedicle screws were inserted either via the 'MIS' or 'open' technique, based on previously described anatomical landmarks. Each vertebra had one 'MIS' and one 'open' technique screw. Specimens were tested with an Instron mechanical testing machine, positioned to allow for testing of direct coaxial force. Load was applied until failure occurred, and load-displacement curves generated for each screw.
Average failure load was found to be 685±399 N for MIS, versus 661±323 N for open technique (P=0.75). The average ultimate failure load was 748±421 N for MIS, versus 772±326 N for open (P=0.74). Average displacement until failure was 0.95±0.49 mm for MIS as compared to 0.95±0.62 mm for open (P=0.996). Axial stiffness was 936±217 N/mm for MIS and 1,016±263 N/mm for open (P=0.19). Average work required to result in failure was 0.84±1.09 J for MIS and 0.82±1.05 J for open (P=0.94).
There was no significant difference in the biomechanical properties of the MIS as compared with open lumbar pedicle screws, when tested until failure under direct coaxial force. The clinical implication may be that there is no significant advantage in the biomechanical properties of MIS versus open lumbar pedicle screw insertion techniques.
评估采用微创外科（MIS）开放技术置入腰椎椎弓根螺钉是否会赋予不同的生物力学参数，进而可能影响失败率。
将人类第1至5节腰椎尸体离断椎体用骨水泥固定。根据先前描述的解剖标志，通过“MIS”或“开放”技术置入椎弓根螺钉。每个椎体有一枚“MIS”技术螺钉和一枚“开放”技术螺钉。用英斯特朗力学试验机对标本进行测试，将其放置成可测试直接同轴力的状态。施加负荷直至发生失效，并为每枚螺钉生成负荷-位移曲线。
发现MIS技术的平均失效负荷为685±399 N，而开放技术为661±323 N（P = 0.75）。MIS技术的平均极限失效负荷为748±421 N，而开放技术为772±326 N（P = 0.74）。MIS技术直至失效的平均位移为0.95±0.49 mm，而开放技术为0.95±0.62 mm（P = 0.996）。MIS技术的轴向刚度为936±217 N/mm，开放技术为1016±263 N/mm（P = 0.19）。导致失效所需的平均功，MIS技术为0.84±1.09 J，开放技术为0.82±1.05 J（P = 0.94）。
在直接同轴力作用下测试直至失效时，MIS腰椎椎弓根螺钉与开放腰椎椎弓根螺钉的生物力学性能无显著差异。临床意义可能是，MIS腰椎椎弓根螺钉置入技术与开放技术相比，在生物力学性能方面无显著优势。
