Parham Foroutan, Ryan D. Quarrington, Michael Pyrros Russo, Boyin Ding, Peter A. Cripton, John J. Costi, Claire F. Jones
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The same has not been demonstrated in multi-segment lower cervical spine specimens under flexion loading (postulated to be the local injury vector associated with CFD).</p>\n </section>\n \n <section>\n \n <h3> Methods</h3>\n \n <p>This study investigated the mechanical response of the bilateral inferior C6 facets of thirteen C5-C7 specimens (67±13 yr, 6 male) during non-destructive constrained flexion, superimposed with each of five axial conditions: (1) 50 N compression (simulating weight of the head); (2-4) 300, 500, and 1000 N compression (simulating the spectrum of intervertebral compression resulting from neck muscle bracing prior to head-first impact and/or externally applied compressive forces); and, (5) 2 mm of C6/C7 distraction (simulating the intervertebral distraction present during inertial loading of the cervical spine by the weight of the head). Linear mixed-effects models (α = 0.05) assessed the effect of axial condition.</p>\n </section>\n \n <section>\n \n <h3> Results</h3>\n \n <p>Increasing amounts of intervertebral compression superimposed on flexion rotations, resulted in increased facet surface strains (range of estimated mean difference relative to Neutral: <i>maximum principal</i> = 77 to 110 με, <i>minimum principal</i> = 126 to 293 με, <i>maximum shear</i> = 203 to 375 με) and angular deflection of the bilateral inferior C6 facets relative to the C6 vertebral body (range of estimated mean difference relative to Neutral = 0.59° to 1.47°).</p>\n </section>\n \n <section>\n \n <h3> Conclusions</h3>\n \n <p>These findings suggest increased facet engagement and higher load transfer through the facet joint, and potentially a higher likelihood of facet fracture under the compressed axial conditions.</p>\n </section>\n </div>","PeriodicalId":14876,"journal":{"name":"JOR Spine","volume":null,"pages":null},"PeriodicalIF":3.4000,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11272947/pdf/","citationCount":"0","resultStr":"{\"title\":\"Facet deflection and strain are dependent on axial compression and distraction in C5–C7 spinal segments under constrained flexion\",\"authors\":\"Parham Foroutan, Ryan D. 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引用次数: 0
摘要
背景：面骨骨折经常与临床观察到的颈椎面骨脱位（CFDs）有关；然而，迄今为止只有一项实验研究使用功能脊柱单元（FSUs）系统地产生了伴有面骨骨折的颈椎面骨脱位。在功能性脊柱单元中，轴向压缩和牵张对颈椎面在与 CFD 相关的椎间运动下的机械响应的作用已被证实。但在屈曲负荷（推测为与 CFD 相关的局部损伤矢量）下的多节段下颈椎标本中，尚未发现同样的情况：本研究调查了 13 个 C5-C7 标本（67±13 岁，6 名男性）的双侧 C6 下椎面在非破坏性约束屈曲时的机械响应，并分别叠加了五种轴向条件：(1) 50 N 压缩（模拟头部重量）；(2-4) 300、500 和 1000 N 压缩（模拟头先撞击和/或外部施加压缩力之前颈部肌肉支撑导致的椎间压缩谱）；以及，(5) 2 mm C6/C7 牵张（模拟头部重量对颈椎造成惯性负载时出现的椎间牵张）。线性混合效应模型（α = 0.05）评估了轴向条件的影响：结果：在屈曲旋转的基础上，椎间压缩量的增加导致切面表面应变增加（相对于中立位的估计平均差范围：最大本构=77至110με，最小本构=126至293με，最大剪切=203至375με），以及双侧下C6切面相对于C6椎体的角度偏移（相对于中立位的估计平均差范围=0.59°至1.47°）：这些研究结果表明，在压缩轴向条件下，关节面啮合增加，通过关节面传递的负荷增加，关节面骨折的可能性也可能增加。
Facet deflection and strain are dependent on axial compression and distraction in C5–C7 spinal segments under constrained flexion
Background
Facet fractures are frequently associated with clinically observed cervical facet dislocations (CFDs); however, to date there has only been one experimental study, using functional spinal units (FSUs), which has systematically produced CFD with concomitant facet fracture. The role of axial compression and distraction on the mechanical response of the cervical facets under intervertebral motions associated with CFD in FSUs has previously been shown. The same has not been demonstrated in multi-segment lower cervical spine specimens under flexion loading (postulated to be the local injury vector associated with CFD).
Methods
This study investigated the mechanical response of the bilateral inferior C6 facets of thirteen C5-C7 specimens (67±13 yr, 6 male) during non-destructive constrained flexion, superimposed with each of five axial conditions: (1) 50 N compression (simulating weight of the head); (2-4) 300, 500, and 1000 N compression (simulating the spectrum of intervertebral compression resulting from neck muscle bracing prior to head-first impact and/or externally applied compressive forces); and, (5) 2 mm of C6/C7 distraction (simulating the intervertebral distraction present during inertial loading of the cervical spine by the weight of the head). Linear mixed-effects models (α = 0.05) assessed the effect of axial condition.
Results
Increasing amounts of intervertebral compression superimposed on flexion rotations, resulted in increased facet surface strains (range of estimated mean difference relative to Neutral: maximum principal = 77 to 110 με, minimum principal = 126 to 293 με, maximum shear = 203 to 375 με) and angular deflection of the bilateral inferior C6 facets relative to the C6 vertebral body (range of estimated mean difference relative to Neutral = 0.59° to 1.47°).
Conclusions
These findings suggest increased facet engagement and higher load transfer through the facet joint, and potentially a higher likelihood of facet fracture under the compressed axial conditions.
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