Time-dependent changes in the lumbar spine's resistancc to bending

doi:10.1016/0268-0033(96)00002-2

Clinical Biomechanics

Volume 11, Issue 4, June 1996, Pages 194-200

https://doi.org/10.1016/0268-0033(96)00002-2 Get rights and content

Abstract

Objective. To show how time-related factors might affect the risk of back injury.

Design. Mechanical testing of cadaveric lumbar motion segments.

Background. High bending stresses acting on the lumbar spine are associated with injuries to the intervertebral discs and ligaments. Since these soft tissues are viscoelastic, the bending stress (‘bending moment’) must depend on the speed of movement and the duration of loading, but this has not previously been quantified.

Methods. Forty-five cadaveric lumbar segments, consisting of two vertebrae and the intervening disc and ligaments, were loaded in combined bending and compression in order to simulate movements and postures in living people. The relationship between flexion angle and bending moment was determined at different loading rates, and after sustained loading in bending and in compression.

Results. Rapid flexion movements increased the peak bending moment by 10–15% compared to slow movements. On average, repeated flexion over a period of 5 min reduced the peak bending moment by 17%, and 5 min of sustained flexion reduced it by 42%. Two hours of compressive creep loading reduced the height of the intervertebral discs by 1.1 mm, increased the range of flexion by 12%, and reduced peak bending moment by 41%.

Conclusions. The scale of these changes suggests that, in life, the risk of bending injury to the lumbar discs and ligaments will depend not only on the loads applied to the spine, but also on loading rate and loading history.

References (39)

RJ Hindle et al.
Mechanical function of the human lumbar interspinous and supraspinous ligaments
J Biomed Eng
(1990)
MA Adams et al.
A technique for quantifying bending moment acting on the lumbar spine in vivo
J Biomech
(1991)
RE Cohen et al.
Viscoelastic creep of collagenous tissue
J Biomech
(1976)
LH Yahia et al.
Rheological properties of the human lumbar spine ligaments
J Biomed Eng
(1991)
P Dolan et al.
The influence of lumbar and hip mobility on the bending stresses acting on the lumbar spine
Clin Biomech
(1993)
W Koeller et al.
Biomechanical properties of human intervertebral discs subjected to axial dynamic compression — influence of age and degeneration
J Biomech
(1986)
S Hasberry et al.
Temperature dependence of the tensile properties of interspinous ligaments of sheep
J Biomed Eng
(1986)
JE Smeathers et al.
Dynamic compressive properties of human lumbar intervertebral joints: a comparison between flesh and thawed specimens
J Biomech
(1988)
P Dolan et al.
Bending and compressive stresses acting on the lumbar spine during lifting activities
J Biomech
(1994)
SM McGill et al.
Creep response of the lumbar spine to prolonged full flexion
Clin Biomech
(1992)

MA Adams et al.

The resistance to flexion of the lumbar intervertebral joint

Spine

(1980)

MA Adams et al.

Prolapsed intervertebral disc. A hyperflexion injury

Spine

(1982)

MA Adams et al.

Gradual disc prolapse

Spine

(1985)

SJ Gordon et al.

Mechanism of disc rupture — a preliminary report

Spine

(1991)

A Shirazi-Adl

Strain in fibres of a lumbar disc. Analysis of the role of lifting in producing disc prolapse

Clin Biomech

(1989)

P Brinckmann et al.

Fatigue fracture of human lumbar vertebrae

Clin Biomech

(1988)

P Brinckmann

Injury of the annulus fibrosus and disc protrusions. An in vitro investigation on human lumbar discs

Spine

(1986)

MA Adams et al.

The relevance of torsion to the mechanical derangement of the lumbar spine

Spine

(1981)

NA Duncan et al.

The role of axial rotation in the etiology of unilateral disc prolapse: an experimental and finite-element analysis

Spine

(1991)

Cited by (141)

Effect of axial compression on stiffness and deformation of human lumbar spine in flexion-extension
2023, Traffic Injury Prevention
The goal of this study was to evaluate the effect of axial compression, employed with a follower-load mechanism, on the response of the lumbar spine in flexion and extension bending. Additional goals include measurement of both the kinetic (stiffness) and kinematic (deformation distribution) responses, evaluating how the responses vary across specimens, and to develop response corridors that can be used to evaluate human body models (HBMs) and anthropomorphic test devices (ATDs).
Seven mid-sized male adult lumbar spines (T12-S1) from postmortem human surrogates were tested in subinjurious flexion and extension bending with 0, 900, and 1800 N of superimposed axial compression. Tests were performed in load-control with a 6-DOF robotic test system that applied pure flexion and extension moments to the specimens, and axial compression was directed along the spine’s curvature via a follower load mechanism powered by force-controlled linear actuators. Load-deformation response data were captured and used to characterize the kinetic response of the lumbar spine in flexion/extension, and how it varies with axial compression. Individual vertebral kinematics were captured using 3D motion capture and the data was used to illustrate the distribution of bending deformation across each intervertebral joint of the spine, as well has how that distribution changes with axial compression. These response data were used to develop elliptical path-length parameterized response corridors for surrogate biofidelity evaluation.
The lumbar spine was found to be generally stiffer in extension than in flexion, but this difference decreased with increasing axial compression. The lumbar spine exhibited a nonlinear kinetic (moment vs. angle) response in flexion that became more linear and stiffer with the addition of axial compression. In flexion without axial load, the majority of the bending deformation occurred at the L5-S1 joint, whereas in extension, deformation was more evenly distributed across the different intervertebral levels, but the locus of deformation was located in the mid-proximal lumbar at L2-L3.
The superposition of axial compression in the lumbar spine affects the kinetic and kinematic response of the lumbar spine in flexion and extension. The response data and approach detailed in this study permit better assessment of ATD and HBM biofidelity.
Effects of a seat-integrated mobilization system on long-haul truck drivers motion activity, muscle stiffness and discomfort during a 4.5-h simulated driving task
2023, Applied Ergonomics
The aim of this study is to evaluate the effects of a seat-integrated mobilization system on motion activity, muscle stiffness and discomfort during prolonged driving.
During a 4.5-h driving task, motion activity, muscle stiffness and discomfort (measured subjectively and objectively) of long-haul truck drivers were determined and compared intra-individually in a test condition with mobilization (seat-integrated stimulation) and a control condition under standardized conditions in a simulated driving study (N = 16).
In the experimental condition, participants showed a significantly increased motion activity and a reduced muscle stiffness compared to the control condition. Furthermore, discomfort occurred significantly more frequently in the control condition.
The mobilization system increased motion activity and reduced discomfort as well as muscle stiffness. Therefore, it provides considerable potential to counteract negative effects of prolonged sitting and to promote truck driver's health.
Biomechanical assessment of a passive back-support exoskeleton during repetitive lifting and carrying: Muscle activity, kinematics, and physical capacity
2022, Journal of Safety Research
Citation Excerpt :
By limiting the trunk flexion, the compression on the lumbar intervertebral discs and the amount of stretching in the posterior ligaments of the spine could be decreased (Ulrey & Fathallah, 2013). Furthermore, the laxity of the passive tissues could also increase with the cumulative mechanical low back load throughout the work, thereby increasing the range of motion of the trunk (Adams & Dolan, 1996; Adams, Dolan, & Hutton, 1987; Coenen et al., 2014). From this point of view, the PBSEs could prevent people from working at the limit flexion angle by limiting the motion of trunk during the lifting (Bonato et al., 2003; Ulrey & Fathallah, 2013).
Introduction: Most people have experienced low back pain (LBP) more or less in their lifetime. Heavier load weight could increase the risk of LBP, especially in repetitive lifting and carrying tasks. The risk could also increase with the frequency of lifting. This study aims to investigate the effects of a passive back-support exoskeleton (PBSE) on trunk muscle activation, kinematics, and physical capacity in a repetitive lifting task and a carrying task in consideration of load weights in a laboratory setting. Results: Results showed that using the PBSE, the activities of the thoracic erector spinae and lumbar erector spinae muscles were reduced significantly by nearly 7% MVC and 3% MVC in the repetitive lifting task and the carrying task, respectively. There was no significant effect of the PBSE on the spine kinematics and physical capacity. Practical Applications: This study supports the use of the PBSE to reduce trunk muscle activity in repetitive lifting and carrying tasks.
About the impact of repetitive spine flexions due to labour on passive mechanics of the lumbar spine
2021, International Journal of Industrial Ergonomics
Citation Excerpt :
Half an hour of palletising changes the stiffness of the passive lumbar torque-angle relation. In contrast to the creep of passive tissue evident with long-term loading (Adams and Dolan, 1996; Solomonow et al., 1999; Kurutz, 2006; Ker, 2007; Pearson et al., 2007) repetitive lumbar flexions provoked by palletising did not result in creep of the lumbar spine's passive mechanics in general, that is, we could not confirm our hypothesis of a right shift of the lumbar passive torque-angle relation. Accordingly, repetitive active flexion of the lumbar spine seems to affect the lumbar spine in a more complex manner than pure passive loading.
Repetitive flexion of the lumbar spine during labour may have an impact on the development of low back pain, but current evidence is sparse. This study focuses on the effect of palletising on the lumbar spine's passive mechanics (flexion characteristics). As other passive structures begin to creep from long-term loading, changes in lumbar passive flexion characteristics have been hypothesised. The lumbar spine's passive flexion characteristics were investigated in 22 volunteers before and after palletising. For comparison, measurements were performed also during relaxed upright standing and while palletising with breaks for exercise. Measurement of passive flexion characteristics was done by a custom-made machine, and posture of the lumbar spine was captured by a kinematographic device. The torque acting within the body on lumbar level L4/5 was analysed. To exclude active forces by lumbar muscles during measurements, lumbar muscle activation was monitored by surface electromyography. Lumbar spine passive stiffness increased significantly (almost 50%) due to palletising. After relaxed standing and palletising with exercise breaks, this change could not be generally verified. The increased stiffness of passive structures of the lumbar spine provoked by palletising over half an hour suggests a degree of tissue fatigue. Even though it is unclear which passive structures change their passive mechanics and how this happens, this highlights the importance of break management during repetitive flexion of the lumbar spine.
The influence of age on spinal and lower limb muscle activity during repetitive lifting
2020, Journal of Electromyography and Kinesiology
This study investigated the effects of age on upper erector spinae (UES), lower erector spinae (LES) and lower body (gluteus maximus; biceps femoris; and vastus lateralis) muscle activity during a repetitive lifting task. Twenty-four participants were assigned to two age groups: ‘younger’ (n = 12; mean age ± SD = 24.6 ± 3.6 yrs) and ‘older’ (n = 12; mean age = 46.5 ± 3.0 yrs). Participants lifted and lowered a box (13 kg) repetitively at a frequency of 10 lifts per minute for a maximum of 20 min. EMG signals were collected every minute and normalised to a maximum voluntary isometric contraction. A submaximal endurance test of UES and LES was used to assess fatigue. Older participants showed higher levels of UES and LES muscle activity (approximately 12–13%) throughout the task, but less fatigue compared to the younger group post-task completion. When lifting, lower-limb muscle activity was generally higher in older adults, although temporal changes were similar. While increased paraspinal muscle activity may increase the risk of back injury in older workers when repetitive lifting, younger workers may be more susceptible to fatigue-related effects. Education and training in manual materials handling should consider age-related differences when developing training programmes.
Assessment of gastroesophageal reflux disease, musculoskeletal symptoms and quality of life in dentists
2020, International Journal of Industrial Ergonomics
Gastroesophageal reflux disease (GERD) has been associated with sick leave, decreased work productivity and poor quality of life. Another possible cause for the development of GERD is the relationship with maintaining the posture in flexion of the spine. The aim of this study was: (1) to compare gastro esophageal reflux with musculoskeletal disorders and quality of life of dentists, (2) to evaluate the association between gastro esophageal reflux such as time in the profession, time working while sitting, musculoskeletal disorders and quality of life of dentists.
83 dentists (23 males and 60 females; average age 39.3 years old) participated in the study, who were evaluated for their time in the profession, sitting time, musculoskeletal disorders, quality of life (SF-12v2) and the GERD symptoms using the Frequency Scale for Symptoms of GERD (FSSG) questionnaire.
The results showed that the majority were female (72.3%) and sendentary (74.7%). A difference was found between the level of GERD with musculoskeletal disorders (p < 0.05) and quality of life (p < 0.05). An association was also found between GERD and working time (p < 0.01), sitting working time (p < 0.05), headache (p < 0.01) and quality of life (p < 0, 01).
This study showed that there was an association with working time, sitting time, musculoskeletal disorders, quality of life and GERD in dentists.

View all citing articles on Scopus

View full text

PaperTime-dependent changes in the lumbar spine's resistancc to bending

Abstract

J Biomed Eng

J Biomech

J Biomech

J Biomed Eng

Clin Biomech

J Biomech

J Biomed Eng

J Biomech

J Biomech

Clin Biomech

The resistance to flexion of the lumbar intervertebral joint

Spine

Prolapsed intervertebral disc. A hyperflexion injury

Spine

Gradual disc prolapse

Spine

Mechanism of disc rupture — a preliminary report

Spine

Strain in fibres of a lumbar disc. Analysis of the role of lifting in producing disc prolapse

Clin Biomech

Fatigue fracture of human lumbar vertebrae

Clin Biomech

Injury of the annulus fibrosus and disc protrusions. An in vitro investigation on human lumbar discs

Spine

The relevance of torsion to the mechanical derangement of the lumbar spine

Spine

The role of axial rotation in the etiology of unilateral disc prolapse: an experimental and finite-element analysis

Spine

Paper
Time-dependent changes in the lumbar spine's resistancc to bending