Sitting versus standing: Does the intradiscal pressure cause disc degeneration or low back pain?

How and why do people with chronic low back pain modify their physical activity? A mixed-methods survey

BACKGROUND

This study investigated the impact of Chronic Low Back Pain (CLBP) on individuals' physical activity (PA) behaviours, specifically, how they modify, cease, or continue PA when experiencing CLBP. The primary aim was to explore the relationship between CLBP and PA and how this is influenced in different contexts (e.g., necessity of a task).

METHODS

A mixed-methods survey was administered to 220 participants, including self-reported outcomes, and capturing responses to three distinct questions related to PA and CLBP. The data was analysed via a content analysis.

RESULTS

The findings revealed that individuals with CLBP are most likely to modify PA in work-related contexts and least likely to cease it in the same setting. Housework emerged as the most common domain for cessation of PA, while work/study activities were predominantly continued. Reasons for these trends were typically task-based rather than health or enjoyment based and influenced by the perceived necessity of the task in question.

CONCLUSION

The study highlights the role of occupational and educational settings in individual responses to CLBP. The findings also highlight a gap in public awareness regarding effective CLBP management strategies, emphasising the need for increased education and awareness programs.

Differences in lumbar spine intradiscal pressure between standing and sitting postures: a comprehensive literature review

Background

Musculoskeletal disorders (MSDs), especially in the lumbar spine, are a leading concern in occupational health. Work activities associated with excessive exposure are a source of risk for MSDs. The optimal design of workplaces requires changes in both sitting and standing postures. In order to secure such a design scientifically proved quantitative data are needed that would allow for the assessment of differences in spine load due to body posture and/or exerted force. Intradiscal pressure (IP) measurement in the lumbar spine is the most direct method of estimating spinal loads. Hence, this study aims at the quantitative evaluation of differences in lumbar spine load due to body posture and exerted forces, based on IP reported in publications obtained from a comprehensive review of the available literature.

Methodology

In order to collect data from studies measuring IP in the lumbar spine, three databases were searched. Studies with IP for living adults, measured in various sitting and standing postures, where one of these was standing upright, were included in the analysis. For data to be comparable between studies, the IP for each position was referenced to upright standing. Where different studies presented IP for the same postures, those relative IPs (rIP) were merged. Then, an analysis of the respective outcomes was conducted to find the possible relationship of IPs dependent on a specific posture.

Results

A preliminary analysis of the reviewed papers returned nine items fulfilling the inclusion and exclusion criteria. After merging relative IPs from different studies, rIP for 27 sitting and 26 standing postures was yielded. Some of the data were useful for deriving mathematical equations expressing rIP as a function of back flexion angle and exerted force in the form of a second degree polynomial equation for the standing and sitting positions. The equations showed that for the standing posture, the increase in IP with increasing back flexion angle is steeper when applying an external force than when maintaining body position only. In a sitting position with the back flexed at 20°, adding 10 kg to each hand increases the IP by about 50%. According to the equations developed, for back flexion angles less than 20°, the IP is greater in sitting than in standing. When the angle is greater than 20°, the IP in the sitting position is less than in the standing position at the same angle of back flexion.

Conclusions

Analysis of the data from the reviewed papers showed that: sitting without support increases IP by about 30% in relation to upright standing; a polynomial of the second degree defines changes in IP as a function of back flexion for for both postures. There are differences in the pattern of changes in IP with a back flexion angle between sitting and standing postures, as back flexion in standing increases IP more than in sitting.

Determinants of diurnal variation in lumbar intervertebral discs and paraspinal muscles: A prospective quantitative magnetic resonance imaging study

PURPOSE

To prospectively investigate the determinants of diurnal variations in lumbar intervertebral discs and paraspinal muscles.

METHOD

71 females aged 19 ∼ 31 years were examined by morning-evening T2 mapping/diffusion kurtosis imaging (DKI), with weight and lifestyle information (time in night bed-rest [TIB], bed-napping, activity time, and sitting time) assessed by standardized questionnaires. Diurnal shifts in T2, mean diffusivity and mean kurtosis (T2-DS, MD-DS and MK-DS; morning-value minus evening-value) were evaluated for L4-S1 discs (normal, Pfirrmann grade Ⅰ/Ⅱ; degenerative, III/IV). T2 and T2-DS were assessed for L4/5 multifidus and erector spinalis.

RESULTS

For normal discs, bed-napping correlated with MD-DS and MK-DS in disc entirety (p = 0.001 and 0.004); increased activity time suggested higher T2-DS in nucleus pulposus (p = 0.004); prolonged sitting time predicted greater T2-DS in disc entirety and posterior inner annulus fibrosus (PI-AF, p ≤ 0.011); decreased TIB and weight suggested lower T2-DS and higher MK-DS in PI-AF (p = 0.001 ∼ 0.035). For degenerative discs, bed-napping predicted lower T2-DS in nucleus pulposus and PI-AF (p = 0.019); increased TIBsuggested higher T2-DS and lower MK-DS in PI-AF (p = 0.006 and 0.034); longer sitting time predicted higher MK-DS in PI-AF (p = 0.020). Paraspinal muscles exhibited diurnal T2 variation (p < 0.001) which did not correlate with lifestyle factors (p > 0.050).

CONCLUSIONS

Lifestyle and weight have causal effects on the diurnal variation of lumbar discs. Bed-rest may correlate with disc hydration and microstructural stability reserves for subsequent daytime activities. Sitting behavior could induce greater dehydration in normal discs and may alleviate diurnal microstructural rearrangement in degenerative discs. T2 mapping and DKI are promising tools to evaluate disc biomechanics in clinics.

Development of a Computational Model of the Mechanical Behavior of the L4-L5 Lumbar Spine: Application to Disc Degeneration

Degenerative changes in the lumbar spine significantly reduce the quality of life of people. In order to fully understand the biomechanics of the affected spine, it is crucial to consider the biomechanical alterations caused by degeneration of the intervertebral disc (IVD). Therefore, this study is aimed at the development of a discrete element model of the mechanical behavior of the L4-L5 spinal motion segment, which covers all the degeneration grades from healthy IVD to its severe degeneration, and numerical study of the influence of the IVD degeneration on stress state and biomechanics of the spine. In order to analyze the effects of IVD degeneration on spine biomechanics, we simulated physiological loading conditions using compressive forces. The results of modeling showed that at the initial stages of degenerative changes, an increase in the amplitude and area of maximum compressive stresses in the disc is observed. At the late stages of disc degradation, a decrease in the value of intradiscal pressure and a shift in the maximum compressive stresses in the dorsal direction is observed. Such an influence of the degradation of the geometric and mechanical parameters of the tissues of the disc leads to the effect of bulging, which in turn leads to the formation of an intervertebral hernia.

Formulation and exploration of novel, intramuscular pressure based, muscle activation strategies in a spine model

Optimization models are often devised to assess spinal stability via estimating individual muscle forces. However, neglecting muscles' fluidic behavior remains an approximation due to the role of muscle pressure in force transmission. The purpose of this study was to leverage a validated Finite Element (FE) model of the spine, inclusive of Intra-Muscular Pressure (IMP), to explore muscle activation strategies towards maintaining equilibrium spinal stability. Three conventional strategies governing minimizing muscle effort, minimizing IVD compressive forces, and maintaining stability at all costs were first investigated to explore model's validity. Thereafter, two novel IMP-based strategies were devised and explored, specifically minimizing and maximizing IMP. The model was previously shown valid in light of in vivo and in silico observations with an average discrepancy of 6%. This being the case, the conventional strategies dictated efficacy in muscular activations whilst maintaining an equilibrium stable position, as quantified in the present paper, with a difference of 9.8% from documented data. In addition, the explored novel IMP-based strategies suggested the presence of a threshold individual muscles IMP, approximately 272 mmHg for the longissimus muscle for example, beyond which muscles potentially start to share radial loads with surrounding tissues, whilst limiting the contraction of the underlying muscles. In conclusion, this study theoretically supports the possibility of activation strategies based on muscular pressure, which the developed, verified, and validated FE spine model was leveraged to investigate. The explored novel IMP-based strategies may have significance in informing clinical applications such as motion analysis and functional electrical stimulation of muscles.

Standing time and daily proportion of sedentary time are associated with pain-related disability in a one month accelerometer measurement in adults with overweight or obesity

OBJECTIVES

The association between the subjective experience of pain-related disability (PRD) and device-measured physical activity (PA) and sedentary behavior (SB) in overweight and obese adults is not well known. The aim of this study was to investigate the associations of pain markers with accelerometer-measured SB duration and different intensities of PA among physically inactive middle-aged adults with overweight or obesity.

METHODS

This cross-sectional analysis included 72 subjects (27 men) with mean age of 57.9 (SD 6.7) years and mean BMI of 31.6 (SD 4.1) kg/m2. SB and standing time (ST), breaks in sedentary time, light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) were measured for four consecutive weeks (mean 25 days, SD 4) with a hip-worn triaxial accelerometer. Headache, musculoskeletal pain, back pain, and PRD were assessed by visual analog scales (VAS) and using the Oswestry disability index (ODI). RAND-36 questionnaire was applied to assess health-related quality of life. The associations were studied by linear models.

RESULTS

ST was positively and SB proportion was negatively associated with PRD when adjusted for age, sex, BMI, accelerometry duration, MVPA, pain medication use, and general health perceptions assessed by RAND-36. No associations were found between ST and back pain. SB or different PA intensities were not associated with pain experience at specific sites.

CONCLUSIONS

Longer daily ST, but not LPA or MVPA is associated with higher level of PRD. Correspondingly, higher proportion of SB is associated with lower level of PRD. This suggests that individuals with PRD prefer to stand, possibly to cope with pain. These results may highlight the importance of habitual standing behaviors in coping with experienced PRD in adults with overweight or obesity.

Comparison of In Vivo Intradiscal Pressure between Sitting and Standing in Human Lumbar Spine: A Systematic Review and Meta-Analysis

Background: Non-specific low back pain (LBP) is highly prevalent today. Disc degeneration could be one of the causes of non-specific LBP, and increased intradiscal pressure (IDP) can potentially induce disc degeneration. The differences in vivo IDP in sitting and standing postures have been studied, but inconsistent results have been reported. The primary objective of this systematic review is to compare the differences in vivo IDP between sitting and standing postures. The secondary objective of this review is to compare effect size estimates between (1) dated and more recent studies and (2) healthy and degenerated intervertebral discs. Methods: An exhaustive search of six electronic databases for studies published before November 2021 was conducted. Articles measuring in vivo IDP in sitting and standing postures were included. Two independent researchers conducted the screening and data extraction. Results: Ten studies that met the inclusion criteria were included in the systematic review, and seven studies with nine independent groups were included in meta-analyses. The sitting posture induces a significantly higher IDP on the lumbar spine (SMD: 0.87; 95% CI = [0.33, 1.41]) than the standing posture. In studies published after 1990 and subjects with degenerated discs, there are no differences in vivo IDP between both postures. Conclusions: Sitting causes higher loads on the lumbar spine than standing in the normal discs, but recent studies do not support this conclusion. Furthermore, the degenerated discs showed no difference in IDP in both postures.

The effects of prolonged sitting, standing, and an alternating sit-stand pattern on trunk mechanical stiffness, trunk muscle activation and low back discomfort

Sit-stand desks continue to be a popular intervention for office work. While previous studies have reported changes in subjective measures, there is limited understanding of how sit-stand work differs from prolonged sitting or standing work, from a biomechanical standpoint. The objective of this study was to investigate the effects of prolonged sitting, prolonged standing, and a sit-stand paradigm on changes in trunk stiffness, low back discomfort, and trunk muscle activation. Twelve healthy participants performed 2 h of computer-based tasks in each protocol, on three different days. The sit-stand protocol was associated with a significant increase in trunk stiffness and a decrease in muscle activation of lumbar multifidus and longissimus thoracis pars thoracis, compared to both prolonged sitting and standing. Both sitting and standing were associated with increased low back discomfort. These findings may be worth exploring in more detail, for why alternating sit-stand patterns may help alleviate low back pain. Practitioner summary: We explored changes in objective and subjective measures related to low back discomfort following prolonged sitting, standing, and alternating sit-stand patterns. Alternating sit-stand pattern was associated with increased trunk stiffness and decreased back muscle activity. Hence, sit-stand desks may have benefits in terms of preventing/mitigating low back pain. Abbreviations: DOF: degree of freedom; EMG: electromyogram; ILL: iliocostalis lumborum pars lumborum; LTL: longissimus thoracis pars lumborum; LTT: longissimus thoracis pars thoracis; LBP: low back pain; LM: lumbar multifidus; MVEs: maximum isometric voluntary exertions; RANOVA: repeated-measure analysis of variance; RMS: root mean square.

An exploratory study on the impact of static and dynamic sitting postures on lumbar and pelvic mobility during visual display terminal work

[Purpose] Limited studies exist on the impact of sustained work at a visual display terminal (VDT) on the position and motion of the pelvis and lumbar spine. We evaluated the changes in movement of the lumbar column and pelvis during VDT work. [Participants and Methods] We evaluated the sitting posture of 20 healthy adults while they performed VDT work. The effects of the sitting posture on lumbo-pelvic position and motion were captured using a three-dimensional accelerometer. Between-posture effects of VDT work were evaluated using an analysis of variance (ANOVA). A two-way ANOVA was used to assess the root mean square (RMS) values of the 80-min VDT work period for each posture. A one-way ANOVA was used to evaluate pre- and post-work changes in RMS values during the finger floor distance test (FFD). [Results] People in the dynamic sitting balance chair (DSBC)-based posture demonstrated significantly higher pelvic RMS values than those in reclining and upright sitting postures. The DSBC-based posture was also associated with significantly higher pre- and post-work lumbar and pelvic RMS values during the FFD than in the reclining and upright sitting postures. [Conclusion] The dynamic balance chair may be an effective method of establishing a pattern of spinal exercise during prolonged sitting.

Is the Agricultural Work a Risk Factor for Koreans Elderly Spinal Sagittal Imbalance?

Objective

A primary degenerative sagittal imbalance has been considered because of unique lifestyles such as the prolonged crouched posture during agricultural work and performing activities of daily living on the floor. Previous papers have reported that sagittal imbalance disease is often seen distinctly in the farming districts of “oriental” countries such as Korea and Japan. However, this finding was only evaluated with the use of X-ray, and other factors such as magnetic resonance imaging (MRI), muscle volume, compression fracture, and laboratory results were not considered. Thus, using these, we evaluate the agricultural work-associated factors for Korean elderly spinal sagittal imbalance.

Methods

We recruited 103 Korean participants who had a sagittal vertical axis (SVA) of >5 cm in this Korean Elderly Sagittal Imbalance Cohort Study. The following were evaluated : radiological parameters, MRI, compression fracture, vitamin D, parathyroid hormone, C-terminal telopeptide, osteocalcin, bone mineral density and muscle fatty change, muscle volume, and health-related quality of life from patients’ survey. Moreover, in this survey, the farmers’ annual working hours were investigated. Subsequently, we analyzed the associated factors for spinal sagittal imbalance depending on occupation.

Results

A total of 46 participants were farmers, and the others were housewives, sellers, and office workers. The farmer group had more SVA (141 vs. 99 mm, p=0.001) and pelvic tilt (31° vs. 24°, p=0.004) and lesser lumbar lordosis (20° vs. 30°, p=0.009) and thoracic kyphosis (24° vs. 33°, p=0.03) than non-farmer group. A significantly positive correlation was noted between the working hour and SVA in the farmer group (p=0.014). The visual analogue scale score for back pain (8.26 vs. 6.96, p=0.008) and Oswestry Disability Index (23.5 vs. 19.1, p=0.003) in the farmer group were higher than that in the non-farmer group, but the Short Form-36 score was not significantly different between the two groups. The Mini-Mental State Exam score was significantly lower in the farmer group than in the non-farmer group (24.85 vs. 26.98, p=0.002).

Conclusion

The farmer group had more sagittal imbalance and back pain in proportion to the working hours even though the muscle and bone factors and general laboratory condition were not significantly different between the two groups. These results supported that the long hours spent in the crouched posture while performing agricultural work were a risk factor for severe sagittal imbalance.

Lumbar Axial Rotation Kinematics in an Upright Sitting and With Forward Bending Positions in Men With Nonspecific Chronic Low Back Pain

STUDY DESIGN

A controlled cross-sectional study.

OBJECTIVE

The aim of this study was to compare the kinematics of lumbar axial rotation while sitting in an upright and forward bending position in men suffering with and without nonspecific chronic low back pain (NSCLBP).

SUMMARY OF BACKGROUND DATA

Lumbar rotation while sitting is an important factor in the mechanism of low back pain. Nevertheless, its kinematics has scarcely been investigated.

METHODS

Range of motion (ROM in), average velocity (AV), maximum velocity (MV), and maximal acceleration (MA) of lumbar rotation while sitting in an upright (UP-sitting) and full forward bending position (FFB-sitting) were examined using an industrial lumbar motion monitor in 50 men (25 with NSCLBP and 25 controls). Pain level and the Rolland Morris questionnaire (RMQ) were also included.

RESULTS

All examined kinematical parameters were significantly lower in men with NSCLBP compared with the controls (↓ROM = 16%-29%; ↓AV = 35%-53%; ↓MV = 3%-46%; ↓MA = 7%-44%) and significantly decreased when moving from UP-sitting to FFB-sitting. In the UP-sitting, the ROM and AV in both groups and the right rotation-MV in the NSCLBP group were always greater during the right rotation compared to the left (NSCLBP = ROM: Δ3.92°, AV: Δ2.74°, MV:Δ3.61°; controls = ROM: Δ3.46°, AV: Δ1.72°). The left rotation-MV was significantly greater compared to the right only in FFB-sitting in the controls (Δ3.03°). In all kinematical parameters in the NSCLBP group, no correlations were found in the visual analogue scale (VAS) levels (4.43 ± 1.47) or RMQ total score (12.32 ± 5.44).

CONCLUSION

The kinematic parameters of lumbar rotation were reduced in men with NSCLBP compared with controls both in an UP-sitting and FFB-sitting. In both groups, NSCLBP and controls, asymmetry in lumbar rotation kinematics was indicated as well as a decrease when moving from UP-sitting to FFB-sitting.

LEVEL OF EVIDENCE

3.

Spinal sagittal alignment, spinal shrinkage and back pain changes in office workers during a workday

Purpose. Prolonged sitting is a risk factor for the appearance of lower back pain during work. The aim of this study was to observe changes in spinal sagittal alignment, height and the perception of back pain in office workers during a workday. Materials and methods. Forty-one office workers (20 women) were enrolled into a cross-sectional study. Height, sitting height and degrees of thoracic kyphosis and lumbar lordosis as well as perceived neck pain, lower back pain and upper back pain were determined, before and after an 8-h workday. Results. At the end of the day, workers had a significant decrease (p = 0.000) in height and sitting height, and upper back pain increased significantly (p = 0.023). In men, spinal shrinkage correlated with neck pain (r = 0.410, p = 0.027), and lumbar lordosis degrees in women correlated negatively with upper back pain at the end of the day (r = -0.440, p = 0.012). Conclusions. Spinal shrinkage equally affects men and women who perform the same work. There are no changes in spinal sagittal alignment throughout the workday in office workers. Office workers show significantly increased pain in the upper back at the end of the day.

The new "Tehran Back Belt": Design then testing during a simulated sitting task improved biomechanical spine muscle activity

Background: Spinal load and muscle activity in occupation settings is an area of increasing concern. Regarding technological advancements, in diverse occupations the spinal loads have increased through constrained seated postures. Back belts are consequently used in prophylactic and conservative management of occupational low back pain (LBP) in two distinct settings, prevention in industry, and treatment in LBP management. Industrial sites utilize belts for LBPprophylaxis on a large scale with their design and user experience (UE) influencing both the effectiveness and the workers’ compliance. This pilot study aims at determining the effectiveness of the new Tehran Back Belt (TBB) and assesses both UE and biomechanical effect (BE) on para-spinal muscle activity in healthy subjects.

Methods: A pretest-posttest study. Stage-1, design and fabrication of the TBB. Stage-2, the UE of the designed belt evaluated in healthy volunteers (n=30) via a checklist. The BE was determined from the level of lumbar extensor and trunk flexor muscle activity gauged during two test conditions of sitting posture (with and without belt) over 35-minute periods.

Results: Most subjects (>90%) reported high ‘ease of use’ and ‘comfort’ while wearing the TBB.The BE statistical analysis showed significantly reduced EMG activity levels for the longissimus(P = 0.012, η²=0.24), rectus abdominis (P=0.024, η²=0.18) and internal oblique (P=0.001,η²=0.44) muscles in belt-use conditions.

Conclusion: Decreased muscle activity while using the TBB is potentially advantageous for workers as spinal muscle activity is significantly reduced. Further investigations for longer duration effects and during real work office-based activities are warranted.

Association between objectively measured static standing and low back pain - a cross-sectional study among blue-collar workers

This study aims to investigate the cross-sectional association between objectively measured total time and temporal patterns of static standing (short bouts: 0-5 min; moderate bouts: >5-10 min; and long bouts: >10 min) during work and leisure and low back pain (LBP) among 698 blue-collar workers. Workers reported LBP on a 0-10 scale. The association between time spent on static standing and LBP was tested with linear regression. A positive association with LBP intensity was found for long bouts of static standing (β = 0.27) during total day (work + leisure), and total static standing time at leisure (β = 0.12). No significant associations were found for static standing during work and LBP intensity. These findings indicate that particularly long bouts of static standing over the entire day contribute to LBP in blue-collar workers. Practitioner Summary: The association between LBP and static standing time was investigated. This study indicates that prolonged time standing during total day and standing during leisure are positively associated with LBP among blue-collar workers. Therefore, practitioners should consider long periods of standing as a potential risk factor for LBP.

Comparison of chairs based on HDsEMG of back muscles, biomechanical and comfort indices, for violin and viola players: A short-term study

This work investigates the effect of different seats on violin and viola players sitting postures using High-Density-surface-Electromyography techniques (HDsEMG), biomechanical and comfort indices. Five types of chairs were assessed on 18 violin and three viola players by comparing: (a) pelvic tilt and kyphosis and lordosis angles, (b) subjective comfort indices, and (c) EMG amplitude of erector spinae and trapezius. Sitting "as you like" on a standard orchestra chair is the condition with the highest subjective comfort (but not significantly different from other chairs). A saddle chair with low back support is associated to the lowest EMG of the erector spinae (p < 0.05) and a saddle stool is associated to the spinal angles closest to those of the standing posture. In 12 out of 21 (57%) musicians, the erector spinae was activated in an intermittent manner, regardless of the chair used. These findings justify further research on the selected chairs, on muscle fatigue and on the intermittent postural control strategy.

Sit-stand workstations and impact on low back discomfort: a systematic review and meta-analysis

BACKGROUND

Sit-stand workstations are proposed solutions to reduce sedentary time at work. Numerous companies are using them to mitigate health concerns such as musculoskeletal discomfort.

OBJECTIVE

To review the literature on sit-stand workstations and low back discomfort.

METHOD

We conducted a meta-analysis on literature published before 17 November 2016 that addressed the relationship between sit-stand workstations and musculoskeletal discomfort, focusing on the low back.

RESULTS

Twelve articles were identified and eight that presented results in means (SD) were included. Among a pain-free population, the standardised mean difference was -0.230 for low back discomfort with use of sit-stand workstations. When applying the SMD to studies using the 10-point pain scale, the effect estimates ranged between -0.30 and -0.51.

CONCLUSION

sit-stand workstations may reduce low back pain among workers. Further research is needed to help quantify dosage parameters and other health outcomes. Practitioner Summary: In a sedentary population, changing posture may reduce the chance of developing low back pain. The literature lacks studies on specific populations such as those who have pre-existing low back pain and also does not adequately address the dosage of sit-stand time required to help reduce pain.

Structural and Chemical Modification to Improve Adhesive and Material Properties of Fibrin-Genipin for Repair of Annulus Fibrosus Defects in Intervertebral Disks

Annulus fibrosus (AF) defects from intervertebral disk (IVD) herniation and degeneration are commonly associated with back pain. Genipin-crosslinked fibrin hydrogel (FibGen) is an injectable, space-filling AF sealant that was optimized to match AF shear properties and partially restored IVD biomechanics. This study aimed to enhance mechanical behaviors of FibGen to more closely match AF compressive, tensile, and shear properties by adjusting genipin crosslink density and by creating a composite formulation by adding Poly(D,L-lactide-co-glycolide) (PDLGA). This study also evaluated effects of thrombin concentration and injection technique on gelation kinetics and adhesive strength. Increasing FibGen genipin concentration from 1 to 36 mg/mL significantly increased adhesive strength (∼5 to 35 kPa), shear moduli (∼10 to 110 kPa), and compressive moduli (∼25 to 150 kPa) with concentration-dependent effects, and spanning native AF properties. Adding PDLGA to FibGen altered the material microstructure on electron microscopy and nearly tripled adhesive strength, but did not increase tensile moduli, which remained nearly 5× below native AF, and had a small increase in shear moduli and significantly decreased compressive moduli. Increased thrombin concentration decreased gelation rate to < 5 min and injection methods providing a structural FibGen cap increased pushout strength by ∼40%. We conclude that FibGen is highly modifiable with tunable mechanical properties that can be formulated to be compatible with human AF compressive and shear properties and gelation kinetics and injection techniques compatible with clinical discectomy procedures. However, further innovations, perhaps with more efficient fiber reinforcement, will be required to enable FibGen to match AF tensile properties.

An investigation into four different sit-stand workstation use schedules

Twelve office workers participated in a study investigating effects of four sit/stand schedules (90-min sit/30-min stand, 80/40, 105/15, and 60/60) via several objective and subjective measures (muscle fatigue, foot swelling, spinal shrinkage, and self-reported discomfort). Results showed that there were no significant differences in shoulder and low back static muscle activities between sitting and standing. Muscle fatigue was developed during workday under all schedules. The longest standing schedule seemed to have a tendency of reducing muscle fatigue. None of the schedules helped or worsened foot swelling and spinal shrinkage. More active break-time activities seemed reducing muscle fatigue and foot swelling. While the self-reported bodily discomfort levels were generally low, the preferred schedules among the participants were varied, although the least standing schedule was the least preferred. We may conclude that effects of using sit-stand workstation to improve musculoskeletal health may be limited but promoting more active break-time activities can help. Practitioner Summary: Sit-stand workstations are used to reduce work-related musculoskeletal disorders. This study shows that office workers prefer sit/stand durations in the range between 1:1 and 3:1. Longer standing may have the potential to reduce muscle fatigue. However, active break-time activities may be more effective in reducing muscle fatigue and foot swelling.

Dynamic MRI in the evaluation of the spine: state of the art

Introduction: Degenerative disease of the spine is a generic term encompassing a wide range of different disease processes, which leads to spinal instability; traumatic/neoplastic events can accelerate this aging process. Therefore, the dynamic nature of the spine and its mobility across multiple segments is difficult to depict with any single imaging modality. Methods: A review of PubMed databases for articles published about kMRI in patients with cervical and lumbar spinal desease was performed. We focused on the physiopathological changes in the transition from supine to upright position in spine instability. Discussion: Until a few years ago, X-ray was the only imaging modality for the spine in the upright position. Of the imaging techniques currently available, MRI provides the greatest range of information and the most accurate delineation of soft-tissue and osseous structures. Conventional MRI examinations of the spine usually are performed in supine position, in functional rest, but the lumbar spine instability is often shown only by upright standing. This can result in negative findings, even in the presence of symptoms. Regardless, the final result is distorted. To overcome this limitation, Kinetic MRI (kMRI) can image patients in a weight-bearing position and in flexed and extended positions, thus revealing abnormalities that are missed by traditional MRI studies. Conclusion: Despite some limitations, the upright MRI can be a complementary investigation to the traditional methods when there are negative results in conventional MRI in symptomatic patients or when surgical therapy is scheduled. (www.actabiomedica.it)

Smudging of the Motor Cortex Is Related to the Severity of Low Back Pain

STUDY DESIGN

Cross-sectional design.

OBJECTIVE

Here we aimed to determine whether motor cortical reorganization in low back pain (LBP) can be identified using noninvasive surface electromyographic (EMG) recordings of back muscles at different lumbar levels, and whether cortical reorganization is related to clinical features of LBP.

SUMMARY OF BACKGROUND DATA

Reorganization of motor regions of the brain may contribute to altered motor control, pain, and disability in chronic LBP. However, data have been limited by the need for invasive recordings of back muscle myoelectric activity. The relationship between altered cortical organization and clinical features of LBP remains unclear.

METHODS

In 27 individuals with recurrent, nonspecific LBP and 23 pain-free controls, we mapped the motor cortical representation of the paraspinal muscles using transcranial magnetic stimulation in conjunction with noninvasive surface EMG recordings at L3 and L5 levels. Clinical measures of pain severity, location, and duration were made.

RESULTS

The results demonstrate a loss of discrete motor cortical organization of the paraspinal muscles in chronic LBP that can be identified using noninvasive EMG recordings. A loss of discrete cortical organization was clearer when surface electrodes were positioned at L3 rather than L5. A novel finding was that altered motor cortical organization (number of discrete peaks and map volume) was associated with the severity and location of LBP.

CONCLUSION

These data suggest that surface EMG positioned at L3 is appropriate for the identification of changes in the motor cortex in LBP. Furthermore, our data have implications for treatment strategies that aim to restore cortical organization in LBP.

LEVEL OF EVIDENCE

2.

Assessment of the intraday variability of anthropometric measurements in the work environment: a pilot study

Sitting for long periods of time, both during work and leisure times, is the typical behavior of the modern society. Especially at work, where there is not much flexibility, adopting the sitting posture for the entire day can cause some short-term and long-term effects. As workers' productivity and well-being relies on working conditions, evaluating the effects caused by work postures assumes a very important role. The purpose of this article was to evaluate the variation of some anthropometric measurements during one typical workday to understand whether the known long-term effects can also be seen and quantified in an 8-h period. Twenty participants were measured before and after work, using traditional anthropometry equipment. The data from the two repetitions were compared using statistical tests. The results showed a slight variation in the anthropometric measurements, some with a tendency to increase over time and others with a tendency to decrease.

Design Requirements for Annulus Fibrosus Repair: Review of Forces, Displacements, and Material Properties of the Intervertebral Disk and a Summary of Candidate Hydrogels for Repair

There is currently a lack of clinically available solutions to restore functionality to the intervertebral disk (IVD) following herniation injury to the annulus fibrosus (AF). Microdiscectomy is a commonly performed surgical procedure to alleviate pain caused by herniation; however, AF defects remain and can lead to accelerated degeneration and painful conditions. Currently available AF closure techniques do not restore mechanical functionality or promote tissue regeneration, and have risk of reherniation. This review determined quantitative design requirements for AF repair materials and summarized currently available hydrogels capable of meeting these design requirements by using a series of systematic PubMed database searches to yield 1500+ papers that were screened and analyzed for relevance to human lumbar in vivo measurements, motion segment behaviors, and tissue level properties. We propose a testing paradigm involving screening tests as well as more involved in situ and in vivo validation tests to efficiently identify promising biomaterials for AF repair. We suggest that successful materials must have high adhesion strength (∼0.2 MPa), match as many AF material properties as possible (e.g., approximately 1 MPa, 0. 3 MPa, and 30 MPa for compressive, shear, and tensile moduli, respectively), and have high tensile failure strain (∼65%) to advance to in situ and in vivo validation tests. While many biomaterials exist for AF repair, few undergo extensive mechanical characterization. A few hydrogels show promise for AF repair since they can match at least one material property of the AF while also adhering to AF tissue and are capable of easy implantation during surgical procedures to warrant additional optimization and validation.

Active self-correction of spinal posture in pain-free women in response to the command "straighten your back"

Evidence is limited regarding the regional changes in spinal posture after self-correction. The aim of the present study was to evaluate whether active self-correction improved standing and sitting spinal posture. Photogrammetry was used to assess regional spinal curvatures and vertical global spine orientation (GSO) in 42 asymptotic women aged 20-24 years. Upper thoracic spine angle and GSO increased in response to self-correction, while the thoracolumbar and lumbosacral angles decreased. Self-correction in the standing position resulted in decreased inclination of the upper thoracic and thoracolumbar spinal angles. Correction of sitting posture reduced the angle of the upper thoracic spine and GSO. The effects of active self-correction on spinal curvature and GSO were different for the standing versus sitting position; the greatest effects of active correction were noted in the thoracic spine. Balanced and lordotic postures were most prevalent in the habitual and actively self-corrected standing positions, whereas the kyphotic posture was most prevalent in the habitual sitting position, indicative that self-correction back posture in the standing position could be an important health-related daily activity, especially during prolonged sitting.

A comparison of trunk biomechanics, musculoskeletal discomfort and productivity during simulated sit-stand office work

Sedentary office work has been shown to cause low back discomfort and potentially cause injury. Prolonged standing work has been shown to cause discomfort. The implementation of a sit-stand paradigm is hypothesised to mitigate discomfort and prevent injury induced by prolonged exposure to each posture in isolation. This study explored the potential of sit-stand to reduce discomfort and prevent injury, without adversely affecting productivity. Twenty-four participants performed simulated office work in three different conditions: sitting, standing and sit-stand. Variables measured included: perceived discomfort, L4-L5 joint loading and typing/mousing productivity. Working in a sit-stand paradigm was found to have the potential to reduce discomfort when compared to working in a sitting or standing only configuration. Sit-stand was found to be associated with reduced lumbar flexion during sitting compared to sitting only. Increasing lumbar flexion during prolonged sitting is a known injury mechanism. Therefore, sit-stand exhibited a potentially beneficial response of reduced lumbar flexion that could have the potential to prevent injury. Sit-stand had no significant effect on productivity. Practitioner Summary: This study has contributed foundational elements to guide usage recommendations for sit-stand workstations. The sit-stand paradigm can reduce discomfort; however, working in a sit-stand ratio of 15:5 min may not be the most effective ratio. More frequent posture switches may be necessary to realise the full benefit of sit-stand.

Thoracic and lumbar posture behaviour in sitting tasks and standing: Progressing the biomechanics from observations to measurements

Few studies quantify spinal posture behaviour at both the thoracolumbar and lumbar spinal regions. This study compared spontaneous spinal posture in 50 asymptomatic participants (21 males) during three conditions: 10-min computer task in sitting (participants naïve to the measure), during their perceived 'correct' sitting posture, and standing. Three-dimensional optical tracking quantified surface spinal angles at the thoracolumbar and lumbar regions, and spinal orientation with respect to the vertical. Despite popular belief that lordotic lumbar angles are 'correct' for sitting, this was rarely adopted for 10-min sitting. In 10-min sitting, spinal angles flexed 24(7-9)deg at lumbar and 12(6-8)deg at thoracolumbar regions relative to standing (P < 0.001). When participants 'corrected' their sitting posture, their thoracolumbar angle -2(7)deg was similar to the angle in standing -1(6)deg (P = 1.00). Males were flexed at the lumbar angle relative to females for 10-min sitting, 'correct' sitting and standing, but showed no difference at the thoracolumbar region.

Effect of seat and table top slope on the biomechanical stress sustained by the musculo-skeletal system

The purpose of this study was to assess the effect of table and seat slope on the biomechanical stress sustained by the musculo-skeletal system. Angular position of the head and trunk, and surface electromyography of eleven postural muscles were recorded while seated under different conditions of seat slope (0°, 15° forward) and table slope (0°, 20° backward). The specific stress sustained by C7-T1 joint was estimated with isometric torque calculation. The results showed that the backward sloping table was associated with a reduction of neck flexion and neck extensors EMG, contrasting with a concurrent overactivity of the deltoideus. The forward sloping chair induced an anterior pelvic tilt, but also a higher activity of the knee (vasti) and ankle (soleus) extensors. It was concluded that sloping chairs and tables favor a more erect posture of the spine, but entails an undesirable overactivity of upper and lower limbs muscles to prevent the body from sliding.

Does Using a Chair Backrest or Reducing Seated Hip Flexion Influence Trunk Muscle Activity and Discomfort? A Systematic Review

OBJECTIVE

This paper systematically reviews the effect of chair backrests and reducing seated hip flexion on low back discomfort (LBD) and trunk muscle activation.

BACKGROUND

Prolonged sitting commonly exacerbates low back pain (LBP). Several modifications to seated posture and chair design have been recommended, including using chairs with backrests and chairs that reduce hip flexion.

METHOD

Electronic databases were searched by two independent assessors. Part 1 of this review includes 26 studies comparing the effect of sitting with at least two different hip angles. In Part 2, seven studies that compared the effect of sitting with and without a backrest were eligible. Study quality was assessed using the PEDro scale.

RESULTS

Significant confounding variables and a relatively small number of randomized controlled trials (RCTs) involving people with LBP complicates analysis of the results. There was moderate evidence that chair backrests reduce paraspinal muscle activation, and limited evidence that chair backrests reduce LBD. There was no evidence that chairs involving less hip flexion reduce LBP or LBD, or consistently alter trunk muscle activation. However, participants in several studies subjectively preferred the modified chairs involving less hip flexion.

CONCLUSION

The limited evidence to support the use of chairs involving less seated hip flexion, or the effect of a backrest, is consistent with the limited evidence that other isolated chair design features can reduce LBP.

APPLICATION

LBP management is likely to require consideration of several factors in addition to sitting position. Larger RCTs involving people with LBP are required.

Magnetic resonance imaging (MRI) of the lumbar spine with dedicated G-scan machine in the upright position: a retrospective study and our experience in 10 years with 4305 patients

PURPOSE

To evaluate the pathological changes of the lumbar spine and the instability of the lumbar intervertebral joints observed in patients with low back pain, with the study of the transition from supine to orthostatic position through the use of dedicated MRI-G-scan machine.

MATERIALS AND METHODS

Within 10 years, 4305 patients, aged between 21 and 80 years old, with history of low back pain with or without sciatica, underwent MRI examinations in upright and in supine position. The open MRI-scanner used is Esaote G-scan, which enables the acquisition of images in supine and standing positions. The used sequences were sagittal T2-weighted FSE, T1-weighted SE and axial 3D HYCE. Patients were divided into two groups: "negatives", with no changes in the two positions (supine and upright), and "positives", with MRI modifications of imaging in upright position.

RESULTS

Orthostatic examination showed MRI changes in 2870 out of 4305 (66.6%) patients, including 1252 males and 1618 females.

CONCLUSIONS

The G-scan is useful to assess instability of the lumbar spine detecting hidden modifications of protrusions and/or herniated discs already present in the supine position. It is also helpful in assessing the presence or modification of spondylolisthesis and lumbar canal stenosis.

Effect of a kneeling chair on lumbar curvature in patients with low back pain and healthy controls: A pilot study

BACKGROUND

The concept of an ideal sitting posture is often used in practice but lacks a basis in evidence.

OBJECTIVE

We designed a cross-sectional, comparative, matched study to determine the effects of chair and posture on lumbar curvature in 10 patients with chronic non-specific low back pain (CLBP; mean pain duration 24 ± 18 months) and 10 healthy matched controls.

METHODS

Pelvic incidence, sacral slope and lumbar curvature were measured on computed radiographs by 2 blinded clinicians for subjects in 2 postures (upright vs slumped sitting) and on 2 chairs (usual flat chair vs kneeling chair).

RESULTS

The reliability of measures was excellent (intraclass correlation coefficient>0.9). As hypothesized, the expected sacral slope and lumbar lordosis changed between standing and sitting on a kneeling chair as compared with a usual chair (P<0.0001) and less in patients than controls (P=0.046) for lordosis only. In addition, as expected, changes were more pronounced with slumped than upright sitting (P<0.0001). An interaction between chairs and postures for lumbar lordosis (P=0.02) indicated more pronounced effects of the chair in slumped sitting. Therefore, lumbar lordosis was reduced less when sitting on a kneeling chair as compared with a usual chair.

CONCLUSIONS

Although healthy subjects showed more reduction in lordosis between standing and sitting, the chair effect was found in both CLBP patients and healthy subjects.

Etiology of lumbar lordosis and its pathophysiology: a review of the evolution of lumbar lordosis, and the mechanics and biology of lumbar degeneration

The goal of this review is to discuss the mechanisms of postural degeneration, particularly the loss of lumbar lordosis commonly observed in the elderly in the context of evolution, mechanical, and biological studies of the human spine and to synthesize recent research findings to clinical management of postural malalignment. Lumbar lordosis is unique to the human spine and is necessary to facilitate our upright posture. However, decreased lumbar lordosis and increased thoracic kyphosis are hallmarks of an aging human spinal column. The unique upright posture and lordotic lumbar curvature of the human spine suggest that an understanding of the evolution of the human spinal column, and the unique anatomical features that support lumbar lordosis may provide insight into spine health and degeneration. Considering evolution of the skeleton in isolation from other scientific studies provides a limited picture for clinicians. The evolution and development of human lumbar lordosis highlight the interdependence of pelvic structure and lumbar lordosis. Studies of fossils of human lineage demonstrate a convergence on the degree of lumbar lordosis and the number of lumbar vertebrae in modern Homo sapiens. Evolution and spine mechanics research show that lumbar lordosis is dictated by pelvic incidence, spinal musculature, vertebral wedging, and disc health. The evolution, mechanics, and biology research all point to the importance of spinal posture and flexibility in supporting optimal health. However, surgical management of postural deformity has focused on restoring posture at the expense of flexibility. It is possible that the need for complex and costly spinal fixation can be eliminated by developing tools for early identification of patients at risk for postural deformities through patient history (genetics, mechanics, and environmental exposure) and tracking postural changes over time.

Targeting chronic recurrent low back pain from the top-down and the bottom-up: a combined transcranial direct current stimulation and peripheral electrical stimulation intervention

BACKGROUND

Mechanisms such as neural sensitization and maladaptive cortical organization provide novel targets for therapy in chronic recurrent low back pain (CLBP).

OBJECTIVE

We investigated the effect of a transcranial direct current stimulation (tDCS) and peripheral electrical stimulation (PES) treatment on pain, cortical organization, sensitization and sensory function in CLBP.

METHODS

Using a placebo-controlled crossover design, 16 individuals received four treatments in separate sessions: (i) anodal tDCS/PES; (ii) anodal tDCS/sham PES; (iii) sham tDCS/PES; or (iv) sham tDCS/sham PES. Pain was assessed at baseline, immediately following, and at 1 and 3 days after treatment. Motor cortical organization, sensitization and sensory function were measured before and immediately after treatment.

RESULTS

Combined tDCS/PES reduced pain and sensitization, normalized motor cortical organization and improved sensory function. The reduction in pain was greater in individuals with more pronounced sensitization. Applied alone, tDCS or PES also reduced pain. However, with the exception of improved sensory function and reduced map volume following PES, clinical and neurophysiological outcomes were unaltered by tDCS or PES applied separately. No changes were observed following sham treatment.

CONCLUSION

Our data suggest a combined tDCS/PES intervention more effectively improves CLBP symptoms and mechanisms of cortical organization and sensitization, than either intervention applied alone or a sham control.

Stochastic resonance whole-body vibration, musculoskeletal symptoms, and body balance: a worksite training study

Background

Stochastic resonance whole-body vibration training (SR-WBV) was tested to reduce work-related musculoskeletal complaints.

Methods

Participants were 54 white-collar employees of a Swiss organization. The controlled crossover design comprised two groups each given 4 weeks of exercise and no training during a second 4-week period. Outcome was daily musculoskeletal well-being, musculoskeletal pain, and surefootedness. In addition, participants performed a behavioral test on body balance prior to when SR-WBV started and after 4 weeks of SR-WBV.

Results

Across the 4-week training period, musculoskeletal well-being and surefootedness were significantly increased (p < 0.05), whereas musculoskeletal pain was significantly reduced only in those who reported low back pain during the last 4 weeks prior to the study (p < 0.05). Body balance was significantly increased by SR-WBV (p < 0.05).

Conclusion

SR-WBV seems to be an efficient option in primary prevention of musculoskeletal complaints and falls at work.

Sustaining biological welfare for our future through consistent science

Physiological anthropology presently covers a very broad range of human knowledge and engineering technologies. This study reviews scientific inconsistencies within a variety of areas: sitting posture; negative air ions; oxygen inhalation; alpha brain waves induced by music and ultrasound; 1/f fluctuations; the evaluation of feelings using surface electroencephalography; Kansei; universal design; and anti-stress issues. We found that the inconsistencies within these areas indicate the importance of integrative thinking and the need to maintain the perspective on the biological benefit to humanity. Analytical science divides human physiological functions into discrete details, although individuals comprise a unified collection of whole-body functions. Such disparate considerations contribute to the misunderstanding of physiological functions and the misevaluation of positive and negative values for humankind. Research related to human health will, in future, depend on the concept of maintaining physiological functions based on consistent science and on sustaining human health to maintain biological welfare in future generations.

The application of a classification-tree model for predicting low back pain prevalence among hospital staff

Low back pain (LBP) is a widespread musculoskeletal condition that frequently occurs in the working-age population (including hospital staff). This study proposes a classification-tree model to predict LBP risk levels in Sacré-Cœur Hospital, Lebanon (as a case study-236 chosen staffs) using various predictor individual and occupational factors. The developed tree model explained 80% of variance in LBP risk levels using standing hours/day (90% in relative importance), job status/sitting hours per day (80% each), body mass index (71%), working days/week (63%), domestic activity hours/week (36%), weight (35%), job dissatisfaction/sitting on ergonomic chairs (30% each), height (28%), gender (27%), sufficient break time (26%), using handling techniques/age (25% each), job stress (24%), marital status/wearing orthopedic insoles/extra professional activity (22% each), practicing prevention measures (20%), children care hours/week (16%), and type of sport activity/sports hours per week, car sitting, and fear of changing work due to LBP (15% each). The overall accuracy of this predictive tree once compared with actual subjects was estimated to be 77%. The proposed tree model can be used by expert physicians in their decision-making for LBP diagnosis among hospital staff.

The prevalence and risk factors of low back pain in rural community residents of Korea

STUDY DESIGN

A community-based, cross-sectional study that is part of the prospective Korean Health and Genome Study.

OBJECTIVE

To determine the prevalence of low back pain (LBP) among middle-aged and elderly rural community residents in Korea and to examine the relevant risk factors, including activities reflecting the Asian lifestyle, and the relationship between radiographical features of degenerative changes in the lumbar spine and LBP.

SUMMARY OF BACKGROUND DATA

The prevalence and implication of LBP among the elderly, particularly Asians, are under-represented in previous reports.

METHODS

Data for LBP were collected for 4181 subjects from a rural farming community. The point and cumulative lifetime prevalences of LBP were obtained in addition to measurement of the severity of LBP. Lateral lumbar spine radiographs were obtained according to a standard protocol.

RESULTS

The mean age of the study subjects was 56 years and 55% were women. The lifetime prevalence of LBP was 61.3%, with women having a higher prevalence. The point and 6-month prevalences were also higher among women. The lifetime, point, and 6-month prevalences increased with age in both sexes, except for lifetime prevalence in men. The prevalence of LBP of grade 3 or more was significantly higher in women and increased significantly with age, particularly in women. Both lifetime and point of prevalence of LBP were significantly associated with age, female sex, and time spent squatting. After adjusting for age and sex, the presence of disc space narrowing, osteophytes, and advanced Kellgren-Lawrence grade in lumbar radiograph was associated with LBP.

CONCLUSION

The prevalence of LBP is comparable between these Korean community residents and other population groups. Risk factors associated with LBP included advanced age, female sex, squatting, the presence of osteophytes, joint space narrowing, and advanced Kellgren-Lawrence grading on lumbar radiograph.

Lumbar spine MRI in upright position for diagnosing acute and chronic low back pain: statistical analysis of morphological changes

Background

Patients with low back pain frequently demonstrate recumbent magnetic resonance imaging (MRI) alterations not always related to homogeneous clinical symptoms. The purpose of this study was to evaluate and quantify the statistical significance of variations of some anatomical parameters of the lumbosacral spine and reveal occult disc pathologies from recumbent to upright position in patients with acute and chronic low back pain.

Materials and methods

Fifty-seven patients complaining of low back pain (27 women, 30 men) underwent dynamic lumbosacral MRI with a 0.25-T tilting system (G-scan Esaote). We settled five parameters for which variations have been evaluated: lumbosacral angle, lordosis angle, L3–L4 intersomatic disc height, L3–L4 interspinous processes distance, and widest anteroposterior dural sac diameter. Images were obtained in both recumbent and upright positions.

Results

Statistically significant differences [one-way analysis of variance (ANOVA), p = 0.0043] were found between each pair of values of parameters sampled in recumbent and upright positions. In 70 % of patients, on visual qualitative analysis only, an increment of disc protrusions and/or spondylolisthesis was found in the upright position; in three cases, in the upright position only, an interarticular pseudocyst was found.

Conclusions

Dynamic MRI with an open-configuration, low-field tilting MRI system is a feasible and promising tool to study degenerative pathology of the spine. Moreover, in cases of low back pain with negative MRI in the recumbent position or in patients with pain in the upright position only, tilting MRI permits visualization of occult spine and disc pathologies in patients with acute or chronic low back pain.

The mechanical effect of anterior pelvic tilt taping on slump sitting by seated workers

The objectives of this study were to determine whether there is a change in the pelvic inclination after about 30 min of slump sitting by seated workers, and if so, to determine whether these changes can be prevented by the application of anterior pelvic tilt taping (APTT). The subjects who consented to participate in the experiment were randomly allocated to two groups: no-APTT group and APTT group. The no-APTT group performed slump sitting for 30 min, and the both pelvic inclinations were remeasured. In the APTT group, the both pelvic inclinations were measured immediately after the application of the APTT, and then again after 30 min of slump sitting. The both pelvic inclinations in the no-APTT group were significantly decreased (p<0.05) after they returned to the upright standing posture. The both pelvic inclinations in the APTT group were significantly increased immediately after the APTT (p<0.05), and this increase was maintained when returning to the upright standing posture after 30 min of slump sitting (p>0.05). We suggest that APTT can be applied as an auxiliary treatment method for preventing changes in pelvic inclination and musculoskeletal problems of low back area by awkward sitting posture in the seated worker.

Alongamento muscular na dor lombar crônica inespecífica: uma estratégia do método GDS

O objetivo deste estudo foi verificar a eficácia do alongamento muscular, usando uma sequência proposta pelo Método Godelieve Denys-Struyf (GDS) na redução da dor, na incapacidade funcional, no aumento da flexibilidade global e na capacidade de contração do músculo transverso do abdome (TrA), em indivíduos com dor lombar crônica inespecífica. Participaram 55 pacientes, de 18 a 60 anos, divididos em dois grupos: Grupo Alongamento (n=30) submetido a exercícios de alongamento, duas vezes por semana, e Grupo Controle (n=25) que não realizou tratamento. A dor foi avaliada pela escala visual analógica; a incapacidade funcional, pelo Índice de Oswestry; a flexibilidade global, pelo terceiro dedo ao solo; e a capacidade de contração do TrA, pela unidade de biofeedback pressórico. Foram realizadas três avaliações, inicial, após 8 e 16 semanas da inicial. Foi considerado nível de significância de α<0,05. Os resultados mostram que o Grupo Alongamento apresentou diminuição na dor, incapacidade funcional e aumentou a flexibilidade global (p<0,001) após 8 e 16 semanas (p<0,05), porém não melhorou a capacidade de contração do TrA (p=0,13). A sequência de alongamentos usada no método GDS mostra-se eficaz na redução da dor, incapacidade funcional e melhora da flexibilidade global em pacientes com dor lombar crônica inespecífica.

On the quantitative relationships between individual/occupational risk factors and low back pain prevalence using nonparametric approaches

OBJECTIVES

To explore dual quantitative relationships between low back pain (LBP) prevalence and different individual and occupational risk factors, and detect the most important ones which can be used as weighted input data in LBP prediction diagnosis models, providing effective tools to help with the implementation of protection and prevention strategies among hospital staff.

METHODS

Fourteen predictor individual risk factors (e.g., age, gender, body mass index BMI [kg/m(2)], domestic activity, etc.) and 17 occupational risk factors (e.g., job status, standing hours/day, sufficient break time, job dissatisfaction, etc.) were collected using self-reported questionnaire among the staff of Sacré-Coeur hospital - Lebanon (used as a case study), and correlated with LBP prevalence using Kendall's tau-b bivariate nonparametric approaches.

RESULTS

This study indicates that among the investigated occupational risk factors, job status, working hours/day, and standing hours/day are the most influencing on LBP prevalence (highly correlated with other factors at 1 and 5% confidence levels). It also shows that strong positive (between 0.25 and 0.65)/negative (from -0.38 to -0.26) statistical correlations to LBP prevalence exist between these risk occupational factors and working days/week, sitting hours/day, job stress, job dissatisfaction, children care, and car driving. The weekly hours of domestic activity, the staff height, and gender type have proven also to be the strongest individual factors in aggravating LBP disease. These individual factors are highly correlated at 1% significance level (ranging between 0.28 and 0.49 for positive correlations, and from -0.49 to -0.25 for negative ones) to children care, weight, extra professional activity, and use of handling techniques.

CONCLUSIONS

These obtained bivariate correlations can be used successfully by expert physicians in their decision making for LBP diagnosis.

Different arm positions and the shape of the thoracic spine can explain contradictory results in the literature about spinal loads for sitting and standing

STUDY DESIGN

Loads acting in vivo on a vertebral body replacement (VBR) and the shape of the back were measured.

OBJECTIVE

To find an explanation for the contradictory results in literature regarding spinal loads for sitting and standing.

SUMMARY OF BACKGROUND DATA

In several in vivo studies, the intradiscal pressure was shown to be higher for sitting than for standing. However, stadiometric measurements, load measurements on internal spinal fixators, and 1 study on intradiscal pressure have shown contradictory results. It therefore remains unknown whether sitting or standing causes greater loading on the spine.

METHODS

Telemeterized VBR was implanted into 5 patients. Implant loads were measured in several sessions during standing and during relaxed sitting on a stool. In the sitting position, the subjects' arms were either hanging at their sides or placed on their thighs. The shape of the back during sitting and standing was additionally determined by rasterstereography.

RESULTS

When sitting with their arms hanging, the loads for the 5 patients ranged from 107% to 228% of the values for standing. A relationship was found between this sit-to-stand load ratio and both the kyphosis angles, which increased from 41° to 67°, and the distance between vertebra prominens and lordosis apex related to the body height, which increased from 0.21 to 0.26. By placing the arms on the thighs, the force on the VBR was reduced by an average of 13% (2%-41%), when compared to sitting with the arms hanging at the sides.

CONCLUSION

The spinal load differences between sitting and standing depend on several key factors, most notably arm position and individual spinal shape. These 2 parameters, however, varied between studies in the literature and may therefore account for the continued contradictory discussion. Patients can reduce their spinal load during sitting by supporting the upper body by the arms.

Características biomecânicas, ergonômicas e clínicas da postura sentada: uma revisão

A posição sentada é a mais adotada nos ambientes de trabalho, na escola e nas atividades de lazer. Porém, a manutenção prolongada dessa posição ocasiona a adoção de posturas inadequadas e sobrecarrega as estruturas do sistema musculoesquelético, o que pode acarretar dor e lesão na coluna lombar. A presente revisão teve como objetivo identificar os fatores biomecânicos, ergonômicos e clínicos envolvidos na sustentação da postura sentada. Para isso, foram consultadas as bases de dados ISI Web of Knowledge, Medline, Pubmed e EBSCO Host, sendo selecionados 72 artigos publicados entre 1965 e 2010. Foi possível identificar que na posição sentada não existe uma postura ideal a ser sustentada, mas algumas posturas são mais recomendadas do que outras, tal como a postura sentada ereta e a postura lordótica. As cadeiras influenciam o padrão da posição sentada: conforme seu design, pode permitir maior variedade de posturas. Modificações na cadeira e a utilização de exercícios para o aumento da resistência muscular e da propriocepção, bem como a reeducação postural, são intervenções úteis para reduzir o impacto causado pela posição sentada prolongada no sistema musculoesquelético.

Causal assessment of occupational sitting and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a common and disabling musculoskeletal disorder that often occurs in a working-age population. Determining the precise causation of LBP remains difficult. Any attempt to implicate a specific occupational activity in the genesis of LBP requires a methodologically rigorous approach.

PURPOSE

To conduct a systematic review of the scientific literature focused on evaluating the causal relationship between occupational sitting and LBP.

STUDY DESIGN

Systematic review of the literature using Medline, EMBASE, CINAHL, Cochrane Library, Occupational Safety and Health database, grey literature, hand-searching occupational health journals, reference lists of included studies, and content experts. Evaluation of study quality using a modified version of the Newcastle-Ottawa Scale. Summary levels of evidence supporting Bradford-Hill criteria for different categories of sitting and types of LBP.

SAMPLES

Studies reporting an association between occupational sitting and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to occupational sitting and the presence or severity of LBP.

METHODS

A systematic review was performed to identify, evaluate, and summarize the literature related to establishing a causal relationship, according to Bradford-Hill criteria, between occupational sitting and LBP.

RESULTS

This search yielded 2,766 citations. Twenty-four studies met the inclusion/exclusion criteria and five were high-quality studies, including two case-controls and three prospective cohorts. Strong, consistent evidence was found for no association between occupational sitting and LBP. A moderate level of evidence was found for the absence of any dose-response trend. Risk estimates evaluating temporality were not statistically significant. Biological plausibility was not discussed in these studies. No evidence was available to assess the experiment criterion.

CONCLUSIONS

This review failed to uncover high-quality studies to support any of the Bradford-Hill criteria to establish causality between occupational sitting and LBP. Strong and consistent evidence did not support criteria for association, temporality, and dose response. Based on these results, it is unlikely that occupational sitting is independently causative of LBP in the populations of workers studied.