Hey Hwee Weng Dennis, Ng Nathaniel Li-Wen, Loh Khin Yee Sammy, Tan Yong Hong, Tan Kimberly-Anne, Moorthy Vikaesh, Lau Eugene Tze Chun, Liu Gabriel, Wong Hee-Kit
University Orthopaedics, Hand and Reconstructive Microsurgery Cluster, National University Health System, Singapore.
Yong Loo Lin School of Medicine, National University Singapore, Singapore.
Asian Spine J. 2021 Feb;15(1):23-31. doi: 10.31616/asj.2019.0198. Epub 2020 Mar 13.
Prospective radiographic comparative study.
To compare and understand the load-bearing properties of each functional spinal unit (FSU) using three commonly assumed, physiological, spinal postures, namely, the flexed (slump sitting), erect (standing) and extended (backward bending) postures.
Sagittal spinal alignment is posture-dependent and influences the load-bearing properties of the spine. The routine placement of intervertebral cages "as anterior as possible" to correct deformity may compromise the load-bearing capabilities of the spine, leading to complications.
We recruited young patients with nonspecific low back pain for <3 months, who were otherwise healthy. Each patient had EOS images taken in the flexed, erect and extended positions, in random order, as well as magnetic resonance imaging to assess for disk degeneration. Angular and disk height measurements were performed and compared in all three postures using paired t-tests. Changes in disk height relative to the erect posture were caclulated to determine the alignment-specific load-bearing area of each FSU.
Eighty-three patients (415 lumbar intervertebral disks) were studied. Significant alignment changes were found between all three postures at L1/2, and only between erect and flexion at the other FSUs. Disk height measurements showed that the neutral axis of the spine, marked by zones where disk heights did not change, varied between postures and was level specific. The load-bearing areas were also found to be more anterior in flexion and more posterior in extension, with the erect spine resembling the extended spine to a greater extent.
Load-bearing areas of the lumbar spine are sagittal alignment-specific and level-specific. This may imply that, depending on the surgical realignment strategy, attention should be paid not just to placing an intervertebral cage "as anterior as possible" for generating lordosis, but also on optimizing load-bearing in the lumbar spine.
前瞻性影像学对比研究。
使用三种常见的、符合生理状态的脊柱姿势，即屈曲（ slumped sitting，弯腰坐姿）、直立（站立）和伸展（向后弯曲）姿势，比较并了解每个功能性脊柱单元（FSU）的承重特性。
脊柱矢状面排列取决于姿势，并影响脊柱的承重特性。为矫正畸形而将椎间融合器“尽可能靠前”的常规放置方式可能会损害脊柱的承重能力，从而导致并发症。
我们招募了患有非特异性下腰痛且病程小于3个月的年轻健康患者。每位患者均以随机顺序在屈曲、直立和伸展位拍摄EOS影像，以及进行磁共振成像以评估椎间盘退变情况。使用配对t检验对所有三种姿势下的角度和椎间盘高度进行测量和比较。计算相对于直立姿势的椎间盘高度变化，以确定每个FSU的特定排列承重区域。
共研究了83例患者（415个腰椎间盘）。在L1/2节段，所有三种姿势之间均发现了显著的排列变化，而在其他FSU节段，仅在直立位和屈曲位之间存在显著变化。椎间盘高度测量显示，以椎间盘高度不变区域为标志的脊柱中性轴在不同姿势之间有所变化，且具有节段特异性。还发现承重区域在屈曲位时更靠前，在伸展位时更靠后，直立脊柱在更大程度上类似于伸展脊柱。
腰椎的承重区域具有矢状面排列特异性和节段特异性。这可能意味着，根据手术矫正策略，不仅应关注为产生前凸而将椎间融合器“尽可能靠前”放置，还应关注优化腰椎的承重。
