A biomechanical study of a self-designed axially controlled compression spinal rod for lumbar spondylolysis
10.3760/cma.j.cn115530-20240109-00019
- VernacularTitle:一种用于腰椎峡部裂的轴向可控加压脊柱棒的研制及生物力学研究
- Author:
Jingyuan LI
1
;
Yulei WANG
;
Nengqi SHAO
;
Fanzhe FENG
;
Jinlong LIANG
;
Lijun WANG
;
Wenxiang HUANG
;
Yongqing XU
;
Yi CUI
Author Information
1. 大理大学临床医学院，大理 671000
- Keywords:
Biomechanics;
Internal fixators;
Lumbar vertebrae;
Spondylolysis
- From:
Chinese Journal of Orthopaedic Trauma
2024;26(7):611-617
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To compare the mechanical properties between our self-designed axially controlled compression spinal rod (ACCSR) and conventional spinal rod (CSR) for lumbar spondylolysis (LS).Methods:This study selected 36 ACCSRs (the ACCSR group) and 36 CSRs (the CSR group), both of which were in a diameter of 6.0 mm and manufactured in the same batch. They were subjected respectively to biomechanical tests of spinal rod and pedicle screw-rod internal fixation system. In spinal rod tests: the stiffness and yield load of the spinal rods were calculated using four-point bending tests ( n=7) and comparisons were made between the 2 groups; spinal rod fatigue tests ( n=8) recorded the successful compression loads after 2.5 million cycles of loading and compared them with the maximum force at the isthmus of a normal adult's unilateral lumbar spine (198.72 N). In tests of the pedicle screw-rod internal fixation system, the axial compression tests ( n=7) measured the axial gripping capacity, the axial torsion tests ( n=7) the torsional gripping capacity, and the lateral compression tests ( n=7) the stiffness and yield load of pedicle screws in the 2 groups respectively. Results:The stiffness [(1,543.37±61.41) N/mm] and yield load [1,338.57 (1,282.00, 1,353.80) N] of ACCSR group were significantly smaller than those of CSR group [(3,797.63±156.15) N/mm and 4,059.95 (3,813.80, 4,090.89) N] ( P<0.05). The spinal rod fatigue tests showed that the respective loads of CSR and ACCSR passing the 2.5 million fatigue tests were 640.00 N and 320.00 N, both larger than the maximum force at the unilateral lumbar isthmus of a normal adult (198.72 N). There were no significant differences between the ACCSR group and the CSR group in the axial gripping capacity and torsional gripping capacity, as well as in stiffness and yield load of screws between the 2 groups ( P>0.05). Conclusions:In fixation of LS, although the yield load, stiffness and fatigue resistance of ACCSR are inferior to those of CSR, the biomechanical properties of the two sets of pedicle screw-rod internal fixation system are comparable. The fatigue resistance of ACCSR can meet the stress requirements of the normal human isthmus.
