The Effect of Standing and Different Sitting Positions on Lumbar Lordosis: Radiographic Study of 30 Healthy Volunteers

Assessing the Preservation of Lumbar Lordotic Curvature in Everyday Sitting Conditions Assessed with an Inertial Measurement System

Background/Objectives: Lumbar lordotic curvature (LLC), closely associated with low back pain (LBP) when decreased, is infrequently assessed in clinical settings due to the spatiotemporal limitations of radiographic methods. To overcome these constraints, this study used an inertial measurement system to compare the magnitude and maintenance of LLC across various sitting conditions, categorized into three aspects: verbal instructions, chair type, and desk task types. Methods: Twenty-nine healthy participants were instructed to sit for 3 min with two wireless sensors placed on the 12th thoracic vertebra and the 2nd sacral vertebra. The lumbar lordotic angle (LLA) was measured using relative angles for the mediolateral axis and comparisons were made within each sitting category. Results: The maintenance of LLA (LLAdev) was significantly smaller when participants were instructed to sit upright (-3.7 ± 3.9°) compared to that of their habitual sitting posture (-1.2 ± 2.4°) (p = 0.001), while the magnitude of LLA (LLAavg) was significantly larger with an upright sitting posture (p = 0.001). LLAdev was significantly larger when using an office chair (-0.4 ± 1.1°) than when using a stool (-3.2 ± 7.1°) (p = 0.033), and LLAavg was also significantly larger with the office chair (p < 0.001). Among the desk tasks, LLAavg was largest during keyboard tasks (p < 0.001), followed by mouse and writing tasks; LLAdev showed a similar trend without statistical significance (keyboard, -1.2 ± 3.0°; mouse, -1.8 ± 2.2°; writing, -2.9 ± 3.1°) (p = 0.067). Conclusions: Our findings suggest that strategies including the use of an office chair and preference for computer work may help preserve LLC, whereas in the case of cueing, repetition may be necessary.

Prevalence and Risk Factors of Degenerative Spondylolisthesis and Retrolisthesis in the Thoracolumbar and Lumbar Spine - An EOS Study Using Updated Radiographic Parameters

STUDY DESIGN

Single centre, cross-sectional study.

OBJECTIVES

The objective is to report the prevalence of spondylolisthesis and retrolisthesis, analyse both conditions in terms of the affected levels and severity, as well as identify their risk factors.

METHODS

A review of clinical data and radiographic images of consecutive spine patients seen in outpatient clinics over a 1-month period is performed. Images are obtained using the EOS® technology under standardised protocol, and radiographic measurements were performed by 2 independent, blinded spine surgeons. The prevalence of both conditions were shown and categorised based on the spinal level involvement and severity. Associated risk factors were identified.

RESULTS

A total of 256 subjects (46.1% males) with 2304 discs from T9/10 to L5/S1 were studied. Their mean age was 52.2(± 18.7) years. The overall prevalence of spondylolisthesis and retrolisthesis was 25.9% and 17.1% respectively. Spondylolisthesis occurs frequently at L4/5(16.3%), and retrolisthesis at L3/4(6.8%). Majority of the patients with spondylolisthesis had a Grade I slip (84.3%), while those with retrolisthesis had a Grade I slip. The presence of spondylolisthesis was found associated with increased age (P < .001), female gender (OR: 2.310; P = .005), predominantly sitting occupations (OR:2.421; P = .008), higher American Society of Anaesthesiology grades (P = .001), and lower limb radiculopathy (OR: 2.175; P = .007). Patients with spondylolisthesis had larger Pelvic Incidence (P < .001), Pelvic Tilt (P < .001) and Knee alignment angle (P = .011), but smaller Thoracolumbar junctional angle (P = .008), Spinocoxa angle (P = .007). Retrolisthesis was associated with a larger Thoracolumbar junctional angle (P =.039).

CONCLUSION

This is the first study that details the prevalence of spondylolisthesis and retrolisthesis simultaneously, using the EOS technology and updated sagittal radiographic parameters. It allows better understanding of both conditions, their mutual relationship, and associated clinical and radiographic risk factors.

Sagittal balance in sitting and standing positions: A systematic review of radiographic measures

Background

Sagittal imbalance can be caused by various etiologies and is among the most important indicators of spinal deformity. Sagittal balance can be restored through surgical intervention based on several radiographic measures. The purpose of this study is to review the normal parameters in the sitting position, which are not well understood and could have significant implications for non-ambulatory patients.

Methods

A systematic review was performed adhering to PRISMA Guidelines. Using R-software, the weighted means and 95% confidence intervals of the radiographic findings were calculated using a random effect model and significance testing using unpaired t-tests.

Results

10 articles with a total of 1066 subjects reported radiographic measures of subjects with no spinal deformity in the sitting and standing position. In the healthy individual, standing sagittal vertical axis -16.8°was significantly less than sitting 28.4° (p < 0.0001), while standing lumbar lordosis 43.3°is significantly greater than sitting 21.3° (p < 0.0001). Thoracic kyphosis was not significantly different between the two groups (p = 0.368). Standing sacral slope 34.3° was significantly greater than sitting 19.5° (p < 0.0001) and standing pelvic tilt 14.0° was significantly less than sitting 33.9° (p < 0.0001).

Conclusions

There are key differences between standing and sitting postures, which could lead to undue stress on surgical implants and poor outcomes, especially for non-ambulatory populations. There is a need for more studies reporting sitting and standing radiographic measures in different postures and spinal conditions.

The Effect of an Active Break Intervention on Nonspecific Low Back Pain and Musculoskeletal Discomfort during Prolonged Sitting among Young People-Protocol for a Randomized Controlled Trial

BACKGROUND

The most recent evidence has shown that the pandemic of COVID-19 caused an increasing problem with spinal pain in the population of teenagers and young adults. This may be explained by prolonged sitting times in flexed positions with electronic devices. Positions maintained for a prolonged time cause overloading of soft tissue and discogenic symptoms. This study aims to evaluate the effectiveness of the active break program in reducing musculoskeletal discomfort and LBP (low back pain) among young people.

METHODS

This will be a randomized controlled study. The participants will be recruited from Bachelor's course students of the Physical Education Department aged 18-25 years. The participants will be assigned to an experimental group (with an active break) and a control group. The group with an active break with lumbar and hip extension exercises will be recommended to take a break for every 30 min of sitting. The control group will receive self-care recommendations. The primary outcomes will be pain intensity (Visual Analogue Scale), disability index (Oswestry Disability Index), and perceived musculoskeletal discomfort during prolonged sitting (Borg scale), assessed at baseline and after the intervention, and the Global Perceived Effect, only assessed after the 12-week intervention. The secondary outcome will be a Post-Intervention Questionnaire (a 5-item self-completed questionnaire), only assessed after the 12-week intervention.

RESULTS

Our main research outcome-exercise protocols and interventions-will lead to the development of recommendations and protocols for the LBP population. It is important to determine the effect of interventions that are feasible and effective in addressing LBP and perceived musculoskeletal discomfort in young people.

CONCLUSIONS

This is the first study examining the effect of active breaks with proposed lumbar and hip extension exercises on reducing or decreasing LBP in students based on a search of the literature. Exercises and recommendations will be the basis for developing proprietary preventative and therapeutic programs, which will be implemented in selected educational institutions.

Sedentary lifestyle of university students is detrimental to the thoracic spine in men and to the lumbar spine in women

BACKGROUND

Sitting for long periods of time and lack of physical activity in young adults can cause postural deterioration leading to rapid onset of fatigue and increase the risk of back pain. We were interested in whether there are gender differences in spinal curvature among university students with a predominantly sedentary lifestyle.

METHODS

20 sedentary female (age 20 ± 0.73 years) and 39 sedentary male university students (age 20 ± 1.08 years) participated in this study. Their thoracic and lumbar curvatures were assessed while standing and sitting using a Spinal Mouse.

RESULTS

In standing, 80.0% of the females and 69.2% of the males had a neutral position of the thoracic spine (33.25° and 35.33°, respectively). However, more males, 30.8%, than females, 10.0%, had hyperkyphosis (54.27° and 47.0°, respectively). Hypokyphosis was found in 10.0% of the females (18.50°) and none in the males. Similarly, 90.0% of the females and 97.4% of the males had neutral position of the lumbar spine (-33.11° and -29.76°, respectively). Increased hyperlordosis was found in 10.0% of the females and 2.6% of the males (-41.0° and -50.0°, respectively). Hypolordosis was not detected in either females or males. In sitting, on the other hand, 70.0% of the females and only 33.3% of the males had a neutral position of the thoracic spine (30.20° and 30.62°, respectively). Increased hyperkyphosis was found in 46.2% of the males (59.76°) and none of the females. 30.0% of the females and 23.1% of the males had light hypokyphosis (47.50° and 46.67°, respectively). Similarly, 70.0% of the females and only 38.5% of the males had a neutral position of the lumbar spine (7.0° and 6.6°, respectively). 35.9% of the males and only 5.0% of the females had a light hypokyphosis (16.14° and 16.0°, respectively). Slightly increased hyperkyphosis was identified in 25.6% of the males and 25.0% of the females (23.9° and 22.5°, respectively).

CONCLUSION

There are significant gender differences in spinal curvature. While in the thoracic spine it was to the detriment of the males when both standing and sitting, in the lumbar spine it is related to the females only when standing. It is therefore necessary to eliminate these spinal deviations in young adults induced by prolonged sitting during university courses by appropriate recovery modalities.

Biomechanical Effects of Different Sitting Postures and Physiologic Movements on the Lumbar Spine: A Finite Element Study

This study used the finite element method(FEM) to investigate how pressure on the lumbar spine changes during dynamic movements in different postures: standing, erect sitting on a chair, slumped sitting on a chair, and sitting on the floor. Three load modes (flexion, lateral bending, and axial rotation) were applied to the FEM, simulating movements of the lumbar spine. Results showed no significant difference in pressure distribution on the annulus fiber and nucleus pulposus, representing intradiscal pressure, as well as on the cortical bone during movements between standing and erect sitting postures. However, both slumped sitting on a chair and sitting on the floor postures significantly increased pressure on the nucleus pulposus, annulus fibrosus, and cortical bone in all three movements when compared to standing or erect sitting on a chair. Notably, sitting on the floor resulted in even higher pressure on the nucleus pulposus and annulus fibers compared to slumped sitting on a chair. The decreased lumbar lordosis while sitting on the floor led to the highest increase in pressure on the annulus fiber and nucleus pulposus in the lumbar spine. In conclusion, maintaining an erect sitting position with increased lumbar lordosis during seated activities can effectively reduce intradiscal pressure and cortical bone stress associated with degenerative disc diseases and spinal deformities.

Reliability of Ultrasound Measurements of the Lumbar Multifidus and Transversus Abdominis Muscles during Lying and Unstable Sitting Positions in Individuals With and Without Chronic Low Back Pain

Background

The reliability studies are limited to support ultrasound usage during dynamic conditions; for example, unstable sitting position.

Objective

This study aims to examine the reliability of ultrasound measurements of the lumbar multifidus and transversus abdominis during lying and unstable sitting positions in individuals with chronic low back pain (CLBP) and asymptomatic individuals considering abnormal lumbar lordosis.

Material and Methods

In this observational study, intrarater within-day and between-day reliability of muscle thickness and contraction ratio of the lumbar multifidus and transversus abdominis muscles were assessed using ultrasound imaging. In total, 40 participants (27 with CLBP, 13 asymptomatic individuals) with abnormal lumbar lordosis were recruited. The degree of lumbar lordosis has been measured by a flexible ruler. The muscle thickness was assessed at lying and sitting on a gym ball for both muscles in three sessions.

Results

Both groups had well to high ICCs of thickness measurement and contraction ratio in the transversus abdominis and lumbar multifidus muscles during both static (ICC=0.71-0.99) and semi-dynamic conditions (ICC=0.73-0.98). The standard error of measurements and minimal detectable changes were rather small in both groups.

Conclusion

Ultrasound imaging is a highly reliable method to assess muscle thicknesses and contraction ratio of the transversus abdominis and lumbar multifidus during different conditions, even in patients with CLBP and abnormal lumbar lordosis.

Alignment of the Sternum and Sacrum as a Marker of Sitting Body Posture in Children

An analysis of literature on the methods of assuming a sitting position and the results of our own research indicated the need to search for biomechanical parameters and existing relationships that would enable a description of sitting body posture. The purpose of this paper is to analyze the relationship between the alignment of the body of sternum and sacrum and the changes in the thoracic and lumbar spine curvatures in children. The study involved 113 subjects aged 9-13 years. A planned simultaneous measurement of the angle parameters of the alignment of the body of sternum and sacrum relative to the body's sagittal axis and the angle parameters of the thoracic and lumbar spine curvatures was performed during a single examination session. The proposed markers of alignment in the corrected sitting body posture are characterized by homogeneous results. A high measurement repeatability was observed when determining the corrected body posture in the study setting. It was noted that changes in the alignment of the body of sternum and sacrum resulted in changes in the thoracic kyphosis and lumbar lordosis angle values, which may be an important component of clinical observations of sitting body posture in children. Implementing the body of sternum alignment angle of about 64° relative to the body's sagittal axis in clinical practice as one of the objectives of postural education may be the target solution for sitting body posture correction in children.

The Effect of a Pelvic Support Chair on Sagittal Lumbosacral Alignment in Sitting Position in Patients with Lower Back Pain

Background

A slouched lumbar posture during sitting is risk factor for the low back pain (LBP). Various chairs have been used to maintain sagittal lumbar lordosis and sacral alignment during sitting. We aimed to demonstrate the effect of a pelvic-support chair on the lumbar lordosis and sacral tilt in patients with LBP.

Methods

We recruited 29 patients with non-specific LBP and 11 healthy subjects in South Korea from Apr 2017 to Mar 2018. The sagittal lumbosacral alignment was examined radiographically in three sitting postures: usual, erect, and sitting in a pelvic-support chair. Five angles [the lumbar lordosis, upper lumbar (ULA), lower lumbar (LLA), lumbosacral (LSA), and sacral slope (SS) angles] were compared between the subjects with LBP and healthy subjects in the three sitting conditions.

Results

There were significant differences in the lumbar lordosis, ULA, LLA, LSA, and SS according to sitting condition (P<.05). All five angles were significantly greater when participants sat erect or in a pelvic-support chair than in their usual sitting position (P<.05). ULA and SS were significantly greater when sitting erect than in a pelvic-support chair (P<.05). LLA was significantly greater in controls than in patients with LBP (P=.042).

Conclusion

The sagittal alignment of the lumbosacral region differed significantly among usual, erect, and pelvic-support chair sitting in patients with LBP and controls. Decreased lordotic curve of the lumbar spine in the usual sitting position can be changed in both patients with LBP and healthy subjects by sitting with pelvic support chair.

The significant relationship among the factors of pelvic incidence, standing lumbar lordosis, and lumbar flexibility in Japanese patients with hip osteoarthritis: A descriptive radiographic study

INTRODUCTION

Spine stiffness is known to increase the risk of total hip replacement (THR) instability. The sagittal posture and lumbo-pelvic kinematics have therefore become parameters of interest when planning THR. We conducted this study to investigate (1) the distribution and characteristics of the spino-pelvic standing alignment, (2) the relationship between pelvic incidence (PI) and standing lumbar lordosis (LL) and lumbar flexibility, in Japanese hip osteoarthritis patients.

HYPOTHESIS

(1) Japanese hip osteoarthritis patients with different sagittal spino-pelvic alignments do not differ markedly in their demographics, PI, or lumbar flexibility; and (2) there is no significant relationship between PI, standing LL, and lumbar flexibility in a population of Japanese hip osteoarthritis patients.

MATERIAL AND METHODS

A retrospective study of radiographs from 945 Japanese patients who consecutively received THR for the treatment of hip osteoarthritis. All patients pre-operatively underwent lateral standing and deep-seated lumbo-pelvic radiography on which the spino-pelvic parameters were measured. The difference between the standing and deep-seated LL angles defined the lumbar flexibility and was calculated as the delta (Δ) LL. Individual spino-pelvic standing alignment was stratified based on the difference between the PI and standing LL ('PI-LL mismatch'). 'PI-LL mismatch' of<-10°, between -10° and 10°, and>10° was defined as hyperlordosis, normolordosis, and flatback, respectively.

RESULTS

In the present study, the spinal alignment of 115/945 (12.2%), 559/945 (59.2%), and 271/945 (28.6%) patients were classified as hyperlordosis, normolordosis, and flatback, respectively. Hyperlordotic patients had significantly lower PI (47.6°±7.8° vs. 52.7°±10.5°, p<0.001) and higher ΔLL (60.6°±12.6° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. Patients with flatback were significantly older (age, 69.1±9.1 years vs. 62.7±9.8 years, p<0.001) with higher PI (56.9°±11.7° vs. 52.7°±10.5°, p<0.001) and lower ΔLL (35.2°±17.4° vs. 51.6°±12.8°, p<0.001) than normolordotic patients. A significant relationship between PI and the standing LL was found in the whole cohort (r=0.409, p=0.009), hyperlordotic (r=0.785, p<0.001), normolordotic (r=0.857, p<0.001), and flatback (r=0.664, p<0.001) patients. Significant relationships between the PI and ΔLL were also found in normolordotic (r=0.442, p=0.004) and flatback (r=0.449, p=0.003) patients but not hyperlordotic patients (r=0.154, p=0.367).

DISCUSSION

A large proportion of Japanese hip osteoarthritis patients have abnormal PI-LL mismatch (12% and 29% have hyperlordosis and flatback, respectively). The PI was a determinant of the standing LL and the lumbar flexibility, especially in the normolordotic and flatback individuals.

LEVEL OF EVIDENCE

III; retrospective diagnostic radiographic study.

The sitting vs standing spine

Background

Planning of surgical procedures for spinal fusion is performed on standing radiographs, neglecting the fact that patients are mostly in the sitting position during daily life. The awareness about the differences in the standing and sitting configuration of the spine has increased during the last years. The purpose was to provide an overview of studies related to seated imaging for spinal fusion surgery, identify knowledge gaps and evaluate future research questions.

Methods

A literature search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) extension for Scoping Reviews (PRISMASc) was performed to identify reports related to seated imaging for spinal deformity surgery. A summary of the finding is presented for healthy individuals as well as patients with a spinal disorder and/or surgery.

Results

The systematic search identified 30 original studies reporting on 1) the pre- and postoperative use of seated imaging of the spine (n=12), 2) seated imaging of the spine for non - surgical evaluation (n=7) and 3) seated imaging of the spine among healthy individuals (12). The summarized evidence illuminates that sitting leads to a straightening of the spine decreasing thoracic kyphosis (TK), lumbar lordosis (LL), the sacral slope (SS). Further, the postural change between standing and sitting is more significant on the lower segments of the spine. Also, the adjacent segment compensates the needed postural change of the lumbar spine while sitting with hyperkyphosis.

Conclusions

The spine has a different configuration in standing and sitting. This systematic review summarizes the current knowledge about such differences and reveals that there is minimal evidence about their consideration for surgical planning of spinal fusion surgery. Further, it identifies gaps in knowledge and areas of further research.

Understanding the Pathophysiology of L5-S1 Loss of Lordosis and Retrolisthesis: An EOS Study of Lumbopelvic Movement Between Standing and Slump Sitting Postures

OBJECTIVE

To understand the pathophysiology of L5-S1 loss of lordosis and retrolisthesis by comparing 2 commonly assumed physiological weight-bearing postures.

METHODS

This was a prospective comparative study of whole-body standing and slump sitting EOS radiographs in clinic patients presenting with back pain or lower limb radicular pain. Patients with prior spinal intervention, malignancy, trauma, inflammatory diseases, transitional lumbosacral vertebra, pregnancy, and L5-S1 retrolisthesis or spondylolisthesis from nondegenerative causes were excluded. C7 sagittal vertical axis, global cervical angle, global thoracic angle, global lumbar angle, thoracolumbar angle, T1-slope, pelvic incidence, pelvic tilt, sacral slope, L5-S1 angle, L5-S1 vertebral translation, L5-S1 disc height, and presence of L4-5 vertebral translation were measured. Univariate and multivariate analyses were performed to identify predictors of L5-S1 lordosis loss and retrolisthesis.

RESULTS

L5-S1 loss of lumbar lordosis (7.02 ± 9.90°, P < 0.001), retrolisthesis (0.07 ± 0.411 cm, P < 0.001), and loss of disc height (0.10 ± 0.23 cm, P < 0.001) occurred when changing from standing to slump sitting along with other sagittal profile changes (P < 0.001). Taller L5-S1 disc height (odds ratio [OR] 2.57, P = 0.04), larger lumbar range-of-motion change (OR 3.82, P = 0.012), lower sacral slope on sitting (OR 2.50, P = 0.043), and presence of L4-5 spondylolisthesis (OR 2.75, P = 0.032) were predictive of larger L5-S1 lordosis loss (>7°) on multivariate analysis, while larger lumbar range-of-motion change (OR 2.21, P = 0.050) and presence of L4-5 spondylolisthesis (OR 3.08, P = 0.023) were predictive of greater L5-S1 retrolisthesis (>0.07 cm).

CONCLUSIONS

Degenerative L5-S1 loss of lordosis and retrolisthesis likely result from long-standing lower lumbar spine bending forces against the posterior ligamentous complex with slump sitting, predisposed by a negatively sloped sacrum and increased lumbar flexibility.

The Association Between Sagittal Plane Alignment and Disc Space Narrowing of Lumbar Spine in Farmers

OBJECTIVE

To investigate whether lumbar lordosis (LL) and lumbar segmental lordosis (LSL) are related to sex, age, low back pain (LBP), and lumbar disc space narrowing (DSN).

METHODS

A total of 569 farmers were recruited. In lateral spine radiograph, LL (L1-L5) and LSL (L1, L2, L3, L4, and L5) were measured using Cobb's method. The differences in LSL values (ΔLSL) according to the presence or absence of a DSN were calculated as LSLDSN - LSLnoDSN for each DSN level.

RESULTS

In male, the lateral spine radiograph showed significantly greater L4-LSL and L5-LSL and smaller L1-LSL and L2-LSL compared to female. LLs in the 50-59 and ≥60 years age groups were significantly smaller compared to those in the <50 years age group. In subjects with LBP, LL and L4-LSL were significantly smaller than in those without. The ΔLSLs at the disc level with DSN showed the greatest decrease: L1-ΔLSL (Δ-3.99°), L2-ΔLSL (Δ-3.31°), L3-ΔLSL (Δ-2.87°), L4-ΔLSL (Δ-3.31°), and L5-ΔLSL (Δ-4.44°) in L1/2, L2/3, L3/4, L4/5, and L5/S1 DSN, respectively. Conversely, distant ΔLSLs were inversely increased: L1-LSL (Δ0.75°) with L4/5 DSN and L2-LSL (Δ0.94°) with L5/S1 DSN.

CONCLUSION

Sagittal plane alignment was significantly associated with sex, age, LBP, and DSN. LSLs around the levels of DSN were decreased, and there was compensational increase of LSL distant to the DSN to maintain the overall LL.

Effect of Posterior Pelvic Tilt Taping on Abdominal Muscle Thickness and Lumbar Lordosis in Individuals With Chronic Low Back Pain and Hyperlordosis: A Single-Group, Repeated-Measures Trial

OBJECTIVE

The purpose of this study was to investigate the effect of posterior pelvic tilt taping (PPTT) on lumbar lordosis, pain, disability, and abdominal muscle thickness in individuals with nonspecific chronic low back pain with hyperlordosis.

METHODS

A prospective, single-group, repeated-measures design was conducted with 31 individuals with nonspecific chronic low back pain (16 men, 15 women) with hyperlordosis (mean ± SD = 59.3° ± 2.9°). Participants' mean age, pain, disability, and lumbar lordosis were, respectively, 35.7 ± 9.9 years, 5.1 ± 1.3, 26.8 ± 11.5, and 59.3° ± 2.9°. The thickness of the abdominal muscles on both sides was measured in the crook lying position by ultrasound imaging. PPTT was performed on both sides. Pain intensity, functional disability, lumbar lordosis angle, and abdominal muscle thickness were measured before PPTT (W0), 1 week after PPTT (W1), and 1 week after PPTT removal (W2).

RESULTS

Analysis revealed significant reductions in lumbar lordosis, pain, and disability, and increased abdominal muscle thickness, at W1 and W2 compared with W0 (P < .001). There were no significant differences in lumbar lordosis or abdominal muscle thickness between W1 and W2.

CONCLUSION

The current study showed in a small group of participants that 1 week of PPTT may improve lumbar lordosis, pain, disability, and abdominal muscle thickness in individuals with nonspecific chronic low back pain with hyperlordosis.

Effect of reclining angle on lumbar lordosis at driving posture: A radiological evaluation

BACKGROUND

Optimal seatback angles for automobile drivers' seats have been investigated based on comfort and back muscle activities; however, radiology supported evidences are scarce.

OBJECTIVE

The aim of this study was to evaluate optimal range of the seatback reclining regarding torso angles for an automobile driver's seat to preserve lumbar lordosis.

METHODS

Thirty-one healthy volunteers were recruited among five body type categories. Lateral lumbar spine X-rays were obtained for the neutral sitting posture without seatback (reference), and with reclining angles of 23∘ to 33∘ by 2∘ intervals. The Cobb angles for the L1-L4, L4-S1, and L1-S1 segments were measured.

RESULTS

The Cobb angle for L4-S1 was nearest to the reference (18.74 ± 1.57∘, mean ± standard error mean) at reclining angles of 29∘ and 31∘ (14.51 ± 1.41∘ and 14.47 ± 1.43∘, respectively). The Cobb angle at L4-S1 between reclining angles of 27∘(12.02 ± 1.31∘) and 29∘ (14.51 ± 1.41∘) were significantly different (p< 0.001). Tall men showed relatively preserved lordosis angles at all reclining angles. Fat men and short women demonstrated prominent loss of lordosis with excessively kyphotic L1-L4 segment.

CONCLUSIONS

Reclining angles of 29∘ to 31∘ revealed to be optimal for preserving lordosis at the L4-S1 segment. Individualized healthcare-related guideline for driver's seat adjustment setting is necessary.

Comparison of Patient Position and Midline Lumbar Neuraxial Access Via Statistical Model Registration to Ultrasound

Patient positioning and needle puncture site are important for lumbar neuraxial anesthesia. We sought to identify optimal patient positioning and puncture sites with a novel ultrasound registration. We registered a statistical model to volumetric ultrasound data acquired from volunteers (n = 10) in three positions: (i) prone; (ii) seated with thoracic and lumbar flexion; and (iii) seated as in position ii, with a 10° dorsal tilt. We determined injection target size and penetration success by simulating lumbar injections on validated registered models. Injection window and target area sizes in seated positions were significantly larger than those in prone positions by 65% in L2-3 and 130% in L3-4; a 10° tilt had no significant effect on target sizes between seated positions. In agreement with computed tomography studies, simulated L2-3 and L3-4 injections had the highest success at the 50% and 75% midline puncture sites, respectively, measured from superior to inferior spinous process. We conclude that our registration to ultrasound technique is a potential tool for tolerable determination of puncture site success in vivo.

The effect of sitting posture on the loads at cervico-thoracic and lumbosacral joints

BACKGROUND:

The sitting in an awkward posture for a prolonged time may lead to spinal or musculoskeletal disease. It is important to investigate the joint loads at spine while sitting.

OBJECTIVE:

The purpose of this study was to investigate the joint moment and antero-posterior (AP) reaction force at cervico-thoracic and lumbosacral joint for various sitting postures.

METHODS:

Twenty healthy males participated in this study. Six sitting postures were defined from three spinal curvatures (slump, flat, and lordosis) and two arm postures (arms-on-chest and arms-forward). Kinematic and kinetic data were measured in six sitting postures from which joint moment and AP reaction force were calculated by inverse dynamics.

RESULTS:

In the cervico-thoracic joint, joint moment and AP reaction force were greater in slump than the flat and lordosis postures (p< 0.001) and also in arms-forward posture compared to arms-on-chest posture. In the lumbosacral joint, joint moment and AP reaction force were greater in slump than flat and lordotic posture (p< 0.001) but there was no difference between different arm postures. The joint loads (moment and AP reaction force) at the cervico-thoriacic joint were closely related to the head flexion angle (r> 0.86) while those at the lumbosacral joint were correlated to the trunk flexion angle (r> 0.77). In slump posture, the joint moments were close to or over the extreme of the daily life such as sit-to-stand and walking. Consequently, if the slump is continued for a long time, it may cause pain and diseases at the cervico-thoracic and lumbosacral joints.

CONCLUSIONS:

The results of the study indicated that the lordosis or flat would be better spinal postures. Also, keeping arms close to body would be desirable to reduce joint loads.

The effect of standing vs. variants of the seated position on lumbar intersegmental angulation and spacing: a radiographic study of 20 asymptomatic subjects

Background

Pain while sitting is the primary complaint of many patients with lumbar spinal ailments, including those with discogenic low back pain and lumbar disc herniations. There has been little basic research on the different mechanical stresses that different sitting positions place on the spine. To demonstrate the effect of different sitting positions on lumbar intersegmental relationships.

Methods

Twenty healthy male volunteer subjects were recruited. Lateral X-rays of the lower lumbar spine were taken in four positions: (I) relaxed lateral standing; (II) "standard" sitting position; (III) sitting on a "kneeling" chair; and (IV) unsupported sitting on a stool. Anterior and posterior disc height, disc space angulation, L1-S1 angulation and interspinous distance were measured.

Results

The L1-S1 lordotic angle in the standing position (48.8°±14.7°) was found to be statistically significantly greater than the angle measured with any of the sitting positions: the kneeling chair (34.0°±17.7°); hard-back chair (28.6°±14.3°); and the stool (16.6°±15.6°). Total average disc height (arithmetic sum of average disc heights L2-S1) in the lumbar spine varied with position: standing (40.5±7.75 mm); hard-back chair (38.5±6.9 mm); kneeling chair (38.4±7.9 mm); stool (36.9±7.1 mm). The mean interspinous distance over all the lumbar levels was significantly greater in each of the three seated positions than in the standing position: standing 6.8±4.5 mm; 11.6°±7.5° for the kneeling chair; 12.9±5.8 mm for the hard-back chair; 16.9±7.0 mm for the stool.

Conclusions

If segmental flexion and segmental loading are the important biomechanical correlates of pain on sitting, such patients should be most comfortable in a kneeling chair, which most closely approximates the standing position. These basic findings will allow better assessment of different seating positions from an ergonomic perspective, and hopefully lead to improvements in chair design.

Influence of posture on relationships between pelvic parameters and lumbar lordosis: Comparison of the standing, seated, and supine positions. A preliminary study

BACKGROUND

Pelvic incidence (PI) is an anatomical parameter that is considered invariable in a given individual. Although changes in posture influence the mobile lumbar spine, lumbar lordosis (LL) and the pelvis are typically evaluated only in the standing position. Thus, whether other positions commonly used during daily activities influence the relationship between LL and PI is unknown. The objective of this study was to determine whether LL and sacral slope (SS) correlated with PI, using two standardised positions, seated and supine, different from the standing position that is generally used.

HYPOTHESIS

We are supposing that lumbar lordosis and sacral sloop are correlated to pelvic incidence whatever the posture. The goal of this study was to confirm or deny this hypothesis, using two standardize positions (sitting and lying) different that the usual standing position. LL and SS correlate with PI in the standing, seated, and supine positions.

METHOD

Lumbar and pelvic parameters were measured on radiographs obtained in the standing, seated, and supine positions in 15 asymptomatic adult volunteers younger than 50years of age. Mean values with their standard deviations were computed and compared across the three positions using ANOVA. Spearman's test was applied to assess correlations.

RESULTS

PI had the same value in all three positions. The L1-S1 LL angle was 54.8±9.8° in the standing position, 15.9±14.6° in the seated position, and 50.2±9.6° in the supine position. Pelvic tilt (PT) in the same three positions was 12.1±6.3°, 37.7±10.4°, and 9.5±5.1°, respectively; and SS was 37.1±6.3°, 11.3±10.8°, and 41±7.2°, respectively. Correlations were strongest in the supine position between PI and LL (r=0.72), LL and SS (r=0.9), and PI and SS (r=0.84).

CONCLUSION

Whereas PI remains unchanged in a given individual, lumbar lordosis and sacral orientation show significant changes across positions used in daily life, with the greatest changes seen in the seated position. During spinal fusion surgery, adjusting LL based on IP is crucial even in patients who have limited physical activity.

LEVEL OF EVIDENCE

IV.

Can different seating aids influence a sitting posture in healthy individuals and does gender matter?

This study determined differences in spinal-pelvic kinematics sitting on (i) mat (ii) block and (iii) novel 10º forward inclined wedge (Buttafly^TM) in a same-subject repeated measures cross-over design in 60 healthy individuals (34 females). Repeated measures ANOVA revealed statistically significant differences between sitting conditions and lumbar and pelvic sagittal angles. Both, the inclined wedge and the block seating aids reduced overall flexion, but the inclined wedge had a greater influence in the lumbar region whilst the block induced the greatest change in the pelvis. This may be relevant for seating aid design personalised to posture type. Statistically significant gender differences were identified in all 3 seating conditions with males adopting more flexed lumbar spine and posteriorly tilted pelvis. Females flexed less in thoracic spine when sitting on an inclined wedge and a block. These statistically significant differences between males and females may provide first explorative direction for bespoke seating aids design.

Central Sagittal Angle of the Sacrum as a New Risk Factor for Patients with Persistent Low Back Pain after Caesarean Section

Study Design

Retrospective.

Purpose

This study investigated the possible association of persistent low back pain (LBP) with caesarean section (CS) under spinal anesthesia.

Overview of Literature

Many women suffer from LBP after CS, which is commonly performed under spinal anesthesia. However, this type of LBP is poorly understood, and there is poor consensus regarding increased risk after spinal anesthesia.

Methods

We examined two groups of patients who underwent cesarean delivery under spinal anesthesia. Group I included patients who presented to a neurosurgical clinic complaining of LBP for at least 6 months. Group II was a control group with patients without LBP. We analyzed clinical and sagittal angle parameters, including age, body mass index, parity, central sagittal angle of the sacrum (CSAS), and sacral slope (SS).

Results

Fifty-three patients participated in this study: 23 (43.1%) in Group I and 30 (56.9%) in Group II. Non-parametric Mann–Whitney U-tests showed that age, parity, and CSAS significantly differed between the two groups at 6 months.

Conclusions

Age, parity, and CSAS appear to be associated with increased risk for LBP after CS under spinal anesthesia. Future prospective studies on this subject may help validate our results.

Measurement of Milwaukee Brace Pad Pressure in Adolescent Round Back Deformity Treatment

Study Design

In this prospective study, we measured the pad pressures of the Milwaukee brace in adolescent hyperkyphosis treatment.

Purpose

We evaluated the skin-brace interface forces exerted by the main pads of the Milwaukee brace.

Overview of Literature

A fundamental factor associated with brace effectiveness in spinal deformity is pad force adjustment. However, few studies have evaluated the in-brace force magnitude and its effect on curve correction.

Methods

Interface forces at four pads of the Milwaukee brace were measured in 73 patients withround back deformity (mean age, 14.04±1.97 years [range, 10–18]; mean initial Cobb angle,67.70°±9.23° [range, 50°–86°]). We used a modified aneroid sphygmomanometer to measure the shoulder and kyphosis pad pressures. Each patient underwent measurement in the standing and sitting positions during inhalation/exhalation.

Results

The mean pad pressures were significantly higher in the standing than in thesitting position, and significantly higher pressures were observed during inhalation compared toexhalation (p=0.001).There were no statistically significant differences between right and left shoulder pad pressures (p>0.05); however, the pressure differences between the right and left kyphosis pads were statistically significant (p<0.05). In a comparison of corrective forces with bracing for less or more than 6 months, corrective force was larger with bracing for less than 6 months (p=0.02). In the standing position, there were no statistically significant correlations between pad pressures and kyphosis curve correction.

Conclusions

In the sitting position, there was a trend toward lower forces at the skin-brace interface; therefore, brace adjustment in the standing position may be useful and more effective. There was no significant correlation between the magnitude of the pad pressures and the degree of in-brace curve correction.

Differences in erect sitting and natural sitting spinal alignment-insights into a new paradigm and implications in deformity correction

BACKGROUND CONTEXT

Sitting spinal alignment is increasingly recognized as a factor influencing strategy for deformity correction. Considering that most individuals sit for longer hours in a "slumped" rather than in an erect posture, greater understanding of the natural sitting posture is warranted.

PURPOSE

This study aimed to investigate the differences in sagittal spinal alignment between two common sitting postures: a natural, patient-preferred posture; and an erect, investigator-controlled posture that is commonly used in alignment studies.

DESIGN/SETTING

This is a randomized, prospective study of 28 young, healthy patients seen in a tertiary hospital over a 6-month period.

PATIENT SAMPLE

Twenty-eight patients (24 men, 4 women), with a mean age of 24 years (range 19-38), were recruited for this study. All patients with first episode of lower back pain of less than 3 months' duration were included. The exclusion criteria consisted of previous spinal surgery, radicular symptoms, red flag symptoms, previous spinal trauma, obvious spinal deformity on forward bending test, significant personal or family history of malignancy, and current pregnancy.

OUTCOME MEASURES

Radiographic measurements included sagittal vertical axis (SVA), lumbar lordosis (LL), thoracolumbar angle (TL), thoracic kyphosis (TK), and cervical lordosis (CL). Standard spinopelvic parameters (pelvic incidence, pelvic tilt [PT], and sacral slope) and sagittal apex and end vertebrae were also measured.

METHODS

Basic patient demographics (age, gender, ethnicity) were recorded. Lateral sitting whole spine radiographs were obtained using a slot scanner in the imposed erect and the natural sitting posture. Statistical analyses of the radiographical parameters were performed comparing the two sitting postures using chi-squared tests for categorical variables and paired t tests for continuous variables.

RESULTS

There was forward SVA shift between the two sitting postures by a mean of 2.9 cm (p<.001). There was a significant increase in CL by a mean of 11.62° (p<.001), and TL kyphosis by a mean of 11.48° (p<.001), as well as a loss of LL by a mean of 21.26° (p<.001). The mean PT increased by 17.68° (p<.001). The entire thoracic and lumbar spine has the tendency to form a single C-shaped curve with the apex moving to L1 (p=.002) vertebra in the majority of patients.

CONCLUSIONS

In a natural sitting posture, the lumbar spine becomes kyphotic and contributes to a single C-shaped sagittal profile comprising the thoracic and the lumbar spine. This is associated with an increase in CL and PT, as well as a constant SVA. These findings lend insight into the body's natural way of energy conservation using the posterior ligamentous tension band while achieving sitting spinal sagittal balance. It also provides information on one of the possible causes of proximal junctional kyphosis or proximal junctional failure.

Medidas angulares da coluna lombar em idosos: comparação entre duas estratégias de análise radiográfica

RESUMO A literatura sobre postura em idosos tem apresentado artigos que medem os ângulos da coluna por diferentes estratégias. Isso pode interferir no diagnóstico postural e impactar na resolução das comorbidades que afetam a coluna desses indivíduos. O objetivo deste estudo foi comparar dois métodos de medida da coluna lombar comumente utilizados em pesquisa. A associação dessas medidas com o ângulo da cifose foi utilizada como base para comparação. Participaram da pesquisa 160 idosos, submetidos a raio-X anteroposterior da coluna lombar. Foram realizadas duas medidas de Cobb para cada radiografia: uma com base em T12-S1 e outra em L1-L5. Somente a medida com base em L1-L5 apresentou associação significativa com o ângulo da cifose. Não houve associação da medida T12-S1 com o ângulo da curva torácica. Nossos achados indicam que o método de Cobb mais adequado para analisar radiografias de coluna lombar em idosos é o do traçado de linhas entre L1-L5.