Range of Motion of the Intact Lumbar Segment: A Multivariate Study of 42 Lumbar Spines

Abstract

BackgroundA thorough understanding of the biomechanical characteristics of the healthy human spine is critical in furthering the treatment of spinal pathology. The goal of this study was to investigate the motion of the intact lumbar spine segment as measured by range of motion (ROM), and to investigate the dependencies thereof on gender and intervertebral level.Materials and MethodsKinematic data was obtained for 42 human lumbar segments (L1-S1) in response to a pure-moment loading protocol in flexion extension (FE), lateral bending (LB) and axial torsion (AT). Data was obtained for 204 individual functional spinal units (91 female, 113 male). Multivariate analysis of variance was conducted to detect differences between genders and intervertebral levels in each mode of loading. Correlations between ROM and donor demographics, including height, weight, and age, were conducted.ResultsROM was significantly greater for females than for males in FE, LB and AT (p<0.001). ROM tended to increase down the vertebral column in FE. L3-4 FE ROM was significantly greater than L1-2 (p=0.024), and L4-5 and L5-S1 FE ROM were significantly greater than for every other level (p<0.003). LB ROM tended to be greater toward the center of the segment with L2-3, L3-4 and L4-5 ROM being significantly greater than both L1-2 (p<0.001) and L5-S1 (p=0.006, p<0.001, p=0.043, respectively). A similar trend was found for AT, however only L1-2 was significantly less than all other levels (p=0.042, p<0.001, p<0.001, and p=0.034 for L2-3, L3-4, L4-5, and L5-S1 respectively).ConclusionThe significant differences in lumbar ROM between male and female spine segments and between the intervertebral levels must be taken into account in study design in order to prevent biases in outcomes. The significant differences in ROM between levels may also have critical implications in the design of spinal implants, particularly those designed to maintain or restore healthy motion.

Variations Among Human Lumbar Spine Segments and Their Relationships to In Vitro Biomechanics: A Retrospective Analysis of 281 Motion Segments From 85 Cadaveric Spines

“…As was seen in this study (Table 2) and other studies, 4,5,13 biomechanics in the lumbar spine are sex specific; female spines are more flexible than male spines. Although donor height and disc height were significantly greater for the male than the female groups in this study, vertebral body height was roughly the same between groups ( Table 1).…”

“…In some published studies involving finite element models of spinal segments, researchers have configured the computer model to mimic experimental behavior seen in limited data sets or to match average behavior from metadata collected using a large number of samples but with inconsistent testing methods. 1,2 For instance, some published experimental data describing the biomechanical behavior of intact and normal lumbar spinal motion segments include specimens from only one sex, 3 specimens without known material or geometric motion segment properties, [3][4][5] or limited donor demographic variables. 6 The load conditions used during these studies vary as well, such as the maximum applied load magnitude (5 to 8 N m), the loading rate, and the possible addition of a compressive preload during bending.…”

High stature and body mass might affect the occurrence of Schmorl’s nodes

“…Cook et al (Cook et al 2015) proved that individuals with greater stature and body mass have decreased mobility of lumbar spine. As already mentioned, more rigid regions of the spine are more inclined to develop Schmorl's nodes.…”

“…Males have bigger nucleus pulposus, which is directly connected with SN formation. Moreover, males have decreased mobility of, at least, lumbar spine (Cook et al 2015). It is also known that males were subject to greater physical loading in past populations (Novak and Šlaus 2011;Novak et al 2012).…”

Range of Motion According to the Fusion Level after Lumbar Spine Fusion: A Retrospective Study

“…The lower portion of the spine bears the most weight and allows for the greatest amount of motion 4) . Lumbar spine motion is very complex because of the need for both stability and mobility.…”