Occupational risk factors for symptomatic lumbar disc herniation; a case-control study

Incidence of and risk factors for lumbar disc herniation with radiculopathy in adults: a systematic review

BACKGROUND

Lumbar disc herniation (LDH) with radiculopathy is associated with greater pain, disability, healthcare use, and costs compared with nonspecific low back pain. Reliable information about its incidence and risk factors were lacking.

QUESTIONS

(1) What is the incidence of lumbar disc herniation (LDH) with radiculopathy in adults? (2) What are the risk factors for LDH with radiculopathy in adults?

METHODS

Systematic review. We searched five electronic databases from 1970 to September 2023. Eligible cohort and case-control studies were identified and independently assessed for risk of bias. A qualitative best evidence synthesis of low and moderate risk of bias studies was conducted.

RESULTS

We critically reviewed 87 studies and synthesised data from 59 (68%) studies; 12 were of low and 47 of moderate risk of bias. The lower and upper bound limits of the 95% CIs of annual incidence estimates ranged from 0.3 to 2.7 per 1000 persons for surgical case definitions, from 0.04 to 1.5 per 1,000 persons for hospital-based case definitions, and from 0.1 to 298.3 per 1,000 persons for clinical case definitions. Factors associated with the development of LDH with radiculopathy included middle-age (30-50 years), smoking, higher BMI, presence of cardiovascular risk factors (in women), and greater cumulative occupational lumbar load by forward bending postures and manual materials handling, with effect sizes ranging from ranging from 1.1 (1.0-1.3) to 3.7 (2.3-6.0).

CONCLUSIONS

Incidence of LDH varies in different populations and according to case definition. Risk factors include individual, behavioural, and work-related variables. Our findings support the need to develop standardised case definitions that validly classify the clinical spectrum of LDH and for future low risk of bias studies examining causal relationships for LDH with radiculopathy in adults.

Occupational psychosocial exposures and chronic low-back pain: a systematic review and meta-analysis

OBJECTIVE

This study aimed to explore the association between occupational psychosocial exposures and chronic low-back pain (LBP) by conducting a systematic review and meta-analysis.

METHODS

The research protocol was registered in PROSPERO. A systematic literature search was performed in six databases, identifying articles complying with predefined inclusion criteria. In our PECOS, we defined outcome as chronic LBP ≥3 months, exposures as occupational psychosocial exposures, and restricted study design to case-control and cohort studies. Two authors independently excluded articles, extracted data, assessed risk of bias, and graded evidence levels. Meta-analyses were performed using random-effects models.

RESULTS

The 20 included articles encompassed six different occupational psychosocial exposures (job control, demand, strain, support, stress, and satisfaction), only 1 had low risk of bias. For all occupational psychosocial exposures, odds ratios ranged from 0.8 to 1.1. Sensitivity analyses based on risk of bias was conducted for two outcomes ie, job control and job demand, finding no differences between high and low-to-moderate risk of bias studies. Using GRADE, we found a very low level of evidence of the association for all occupational psychosocial exposures.

CONCLUSION

In this study, we found no association between occupational psychosocial exposures and chronic LBP. However, it is important to underline that the level of evidence was very low. High quality studies are highly warranted.

Risk Factors for Surgical Treatment of Lumbar Degenerative Disc Disease in Middle-aged and Older Women: A Prospective Case-Control Study of 2370 Subjects

OBJECTIVE

Given the distinct physiological and societal traits between women and men, we propose that there are distinct risk factors for lumbar degenerative disc disease surgeries, including lumbar disc herniation (LDH) and lumbar spinal stenosis (LSS), in middle-aged and older populations. However, few studies have focused on middle-aged and older women. This study aims to identify these risk factors specifically in this population.

METHODS

In this case-control study, the study group comprised 1202 women aged ≥ 45 years who underwent operative treatment of lumbar degenerative disc disease (LDH, n = 825; LSS, n = 377), and the control group comprised 1168 women without lumbar disease who visited a health examination clinic during the same period. The study factors included demographics (age, body mass index [BMI], smoking, labor intensity, and genetic history), female-specific factors (menopausal status, number of deliveries, cesarean section, and simple hysterectomy), surgical history (number of abdominal surgeries, hip joint surgery, knee joint surgery, and thyroidectomy), and systemic diseases (hypercholesterolemia, hypertriglyceridemia, hyper-low-density lipoprotein cholesterolemia, hypertension, diabetes, cardiovascular disease, and cerebrovascular disease). Multivariate binary logistic regression analysis was used to calculate the odds ratio (OR) and 95% confidence interval (95% CI) of associated factors.

RESULTS

The risk factors for surgical treatment of LDH in middle-aged and older women included BMI (OR = 1.603), labor intensity (OR = 1.189), genetic history (OR = 2.212), number of deliveries (OR = 1.736), simple hysterectomy (OR = 2.511), hypertriglyceridemia (OR = 1.932), and hyper-low-density lipoprotein cholesterolemia (OR = 2.662). For surgical treatment of LSS, the risk factors were age (OR = 1.889), BMI (OR = 1.671), genetic history (OR = 2.134), number of deliveries (OR = 2.962), simple hysterectomy (OR = 1.968), knee joint surgery (OR = 2.527), hypertriglyceridemia (OR = 1.476), hyper-low-density lipoprotein cholesterolemia (OR = 2.413), and diabetes (OR = 1.643). Cerebrovascular disease was a protective factor against surgery for LDH (OR = 0.267).

CONCLUSIONS

BMI, genetic history, number of deliveries, simple hysterectomy, hypertriglyceridemia, and hyper-low-density lipoprotein cholesterolemia were independent risk factors for surgical treatment of both LDH and LSS in middle-aged and older women. Two disparities were found: labor intensity was a risk factor for LDH patients, and knee joint surgery and diabetes were risk factors for LSS patients.

Effect of muscular fatigue on the cumulative lumbar damage during repetitive lifting task: a comparative study of damage calculation methods

Several methods have been put forward to quantify cumulative loads; however, limited evidence exists as to the subsequent damages and the role of muscular fatigue. The present study assessed whether muscular fatigue could affect cumulative damage imposed on the L5-S1 joint. Trunk muscle electromyographic (EMG) activities and kinematics/kinetics of 18 healthy male individuals were evaluated during a simulated repetitive lifting task. A traditional EMG-assisted model of the lumbar spine was modified to account for the effect of erector spinae fatigue. L5-S1 compressive loads for each lifting cycle were estimated based on varying (i.e. actual), fatigue-modified, and constant Gain factors. The corresponding damages were integrated to calculate the cumulative damage. Moreover, the damage calculated for one lifting cycle was multiplied by the lifting frequency, as the traditional approach. Compressive loads and the damages obtained through the fatigue-modified model were predicted in close agreement with the actual values. Similarly, the difference between actual damages and those driven by the traditional approach was not statistically significant (p = 0.219). However, damages based on a constant Gain factor were significantly greater than those based on the actual (p = 0.012), fatigue-modified (p = 0.017), and traditional (p = 0.007) approaches.Practitioner summary: In this study, we managed to include the effect of muscular fatigue on cumulative lumbar damage calculations. Including the effect of muscular fatigue leads to an accurate estimation of cumulative damages while eliminating computational complexity. However, using the traditional approach also appears to provide acceptable estimates for ergonomic assessments.

Understanding the etiopathogenesis of lumbar intervertebral disc herniation: From clinical evidence to basic scientific research

Lumbar intervertebral disc herniation, as a leading cause of low back pain, productivity loss, and disability, is a common musculoskeletal disorder that results in significant socioeconomic burdens. Despite extensive clinical and basic scientific research efforts, herniation etiopathogenesis, particularly its initiation and progression, is not well understood. Understanding herniation etiopathogenesis is essential for developing effective preventive measures and therapeutic interventions. Thus, this review seeks to provide a thorough overview of the advances in herniation-oriented research, with a discussion on ongoing challenges and potential future directions for clinical, translational, and basic scientific investigations to facilitate innovative interdisciplinary research aimed at understanding herniation etiopathogenesis. Specifically, risk factors for herniation are identified and summarized, including familial predisposition, obesity, diabetes mellitus, smoking tobacco, selected cardiovascular diseases, disc degeneration, and occupational risks. Basic scientific experimental and computational research that aims to understand the link between excessive mechanical load, catabolic tissue remodeling due to inflammation or insufficient nutrient supply, and herniation, are also reviewed. Potential future directions to address the current challenges in herniation-oriented research are explored by combining known progressive development in existing research techniques with ongoing technological advances. More research on the relationship between occupational risk factors and herniation, as well as the relationship between degeneration and herniation, is needed to develop preventive measures for working-age individuals. Notably, researchers should explore using or modifying existing degeneration animal models to study herniation etiopathogenesis, as such models may allow for a better understanding of how to prevent mild-to-moderately degenerated discs from herniating.

A Systematic Review of Clinical Practice Guidelines for Persons With Non-specific Low Back Pain With and Without Radiculopathy: Identification of Best Evidence for Rehabilitation to Develop the WHO's Package of Interventions for Rehabilitation

OBJECTIVE

To Identify evidence-based rehabilitation interventions for persons with non-specific low back pain (LBP) with and without radiculopathy and to develop recommendations from high-quality clinical practice guidelines (CPGs) to inform the World Health Organization's (WHO) Package of Interventions for Rehabilitation (PIR).

DATA SOURCE

We searched MEDLINE, EMBASE, CINAHL, PsycINFO, National Health Services Economic Evaluation Database, Health Technology Assessment Database, PEDro, the Trip Database, the Index to Chiropractic Literature and the gray literature.

STUDY SELECTION

Eligible guidelines were (1) published between 2009 and 2019 in English, French, Italian, or Swedish; (2) included adults or children with non-specific LBP with or without radiculopathy; and (3) assessed the benefits of rehabilitation interventions on functioning. Pairs of independent reviewers assessed the quality of the CPGs using AGREE II.

DATA SYNTHESIS

We identified 4 high-quality CPGs. Recommended interventions included (1) education about recovery expectations, self-management strategies, and maintenance of usual activities; (2) multimodal approaches incorporating education, exercise, and spinal manipulation; (3) nonsteroidal anti-inflammatory drugs combined with education in the acute stage; and (4) intensive interdisciplinary rehabilitation that includes exercise and cognitive/behavioral interventions for persistent pain. We did not identify high-quality CPGs for people younger than 16 years of age.

CONCLUSION

We developed evidence-based recommendations from high-quality CPGs to inform the WHO PIR for people with LBP with and without radiculopathy. These recommendations emphasize the potential benefits of education, exercise, manual therapy, and cognitive/behavioral interventions.

Occupational mechanical exposures as risk factor for chronic low-back pain: a systematic review and meta-analysis

OBJECTIVES

The association between occupational mechanical exposures and low-back pain (LBP) has been studied in several systematic reviews. However, no systematic review addressing chronic LBP exists. The aim of this systematic review and meta-analysis was to examine the association between occupational mechanical exposures and chronic LBP.

METHODS

The study was registered in PROSPERO. We used an existing systematic review to identify articles published before January 2014. For studies published between January 2014 and September 2022, a systematic literature search was conducted in six databases. Two authors independently excluded articles, extracted data, and assessed risk of bias and level of evidence (GRADE). Meta-analyses were conducted using random-effects models comparing highest versus lowest exposure group with sensitivity analyses based on study quality (low/moderate versus high risk of bias), study design (cohort versus case-control), and outcome definition (non-specific LBP versus specific chronic LBP).

RESULTS

Twenty-six articles were included. Highest pooled odd ratios (OR) were found for combined mechanical exposures [OR 2.2, 95% confidence interval (CI) 1.4-3.6], lifting/carrying loads (OR 1.7, 95% CI 1.4-2.2), and non-neutral postures (OR 1.5, 95% CI 1.2-1.9). For the remaining mechanical exposures (ie, whole-body vibrations, standing/walking, and sitting), OR ranged between 1.0 and 1.4. In the sensitivity analyses, generally, higher pooled OR were found in low/moderate risk of bias studies, case-control studies, and studies of specific chronic LBP.

CONCLUSIONS

Moderate evidence of an association was found for lifting/carrying loads, non-neutral postures, and combined mechanical exposures. Low or very low evidence was found for whole-body vibrations, standing/walking, and sitting. Studies using standardized exposure definition, metric, and technical measurements are highly warranted.

Patient-related risk factors and lifestyle factors for lumbar degenerative disc disease: a systematic review

OBJECTIVE

Back pain is a very widespread disease pattern and is one of the most frequent causes for consultation of a physician in general. In most cases, discogenic changes are the pathomorphological correlate of back pain. Numerous risk factors have been identified for these degenerative changes, but the influence and significance of the risk factors remain unclear, which was the aim of this systematic review.

METHODS

A systematic literature search of the commonly used Pubmed database was performed using specific MESH terms. Further selection of the included studies was performed according to the PRISMA scheme, taking into account scientific merit as well as the relation to the research question.

RESULTS

A total of 111 studies out of 1035 found were finally included in the literature search. 134 risk factors for disc degeneration and disc herniation were identified. These were divided into (1) patient-specific risk factors (n░=░34), (2) radiological risk factors (n░=░31), (3) lifestyle risk factors (n░=░6), (4) workplace-related risk factors (n░=░12), (5) genetic risk factors (n░=░50), and (6) other risk factors (n░=░1). Non-adjustable risk factors were age >50 years (OR 1.7/year), female gender (OR 1.41), family disposition (OR 4.0), comorbidities like atherosclerosis (OR 2.24), arthritic changes in other joints (OR 3.1) and history of injuries of the back (OR 3.1). Adjustable factors were elevated BMI (OR 2.77), comorbidities like hypertension (OR 1.25), dyslipidemia (OR 1.26) and diabetes mellitus (OR 6.8), as well as lifestyle habits like smoking (OR 3.8).

DISCUSSION

In summary, intervertebral disc degenerations and herniations represent multifactorial events whose risk factors can be partly influenced and partly not influenced. This systematic review highlights the current state of knowledge as a basis for creating patient-specific algorithms to calculate risk for the development or progression of degenerative disc changes and disc herniations.

Trunk muscle forces and spinal loads during heavy deadlift: Effects of personalization, muscle wrapping, muscle lever arm, and lumbopelvic rhythm

Heavy deadlift is used as a physical fitness screening tool in the U.S. Army. Despite the relevance of such a screening tool to military tasks performed by Service Members, the biomechanical impact of heavy deadlift and its risk of low-back injury remain unknown. A kinematics-driven musculoskeletal model of spine was implemented to investigate biomechanics of the lower back in a volunteer (23 years old, height of 1.82 m, and body mass of 98.8 kg) during a 68 kg deadlift. In search of protective mechanisms, effects of model personalization and variations in trunk musculature and lumbopelvic rhythm were also investigated. The net moment, compression and shear forces at the L5-S1 reached peaks of 684 Nm, 17.2 and 4.2 kN, respectively. Geometrical personalization and changes in lumbopelvic rhythm had the least effects on predictions while increases in muscle moment arms (40%) had the largest effects that caused, respectively, 32% and 36% decrease in the maximum compressive and shearing forces. Initiating wrapping of back muscles at farther distances from the spine had opposing effects on spinal loads; peak compression at the L5-S1 decreased by 12% whereas shear increased by 19%. Despite mechanisms considered, spinal loads during heavy deadlift exceed the existing evidence concerning the threshold of injury for spinal segments, suggesting the vulnerability to injury. Chronic exposure to such high-spinal loads may lead to (micro) fractures, degeneration, pathoanatomical changes and finally low-back pain.

Successful rehabilitation program after AIS/Frankel C paraplegia through a recently operated lumbar disc hernia

Intervertebral disc herniation is the pathological process by which fragments of the nucleus pul-posus tear the fibers of the annulus fibrosus and come into contact with the root of the spinal nerve (1). The most significant functional damage generated by the lumbar disc herniation is paraplegia and can be ameliorated by an early and staged specific rehabilitation program. Materials and Methods: This paper presents the case of a 56-year-old patient who was admitted to the Neurosurgery Clinic (NCH) III of SCUBA for low back pain and motor deficit, AIS Frankel C paraplegia. The left lower limb was more affected than the right one. It occurred following a thoraco-lumbar medullary compression and a paramedian lumbar disc herniation L3. The pa-tient was treated surgically. Subsequently, the patient was transferred to the Neuro-Muscular Recovery Clinic of SCUBA for the specific rehabilitation treatment, with indication for mobiliza-tion. He was dynamically evaluated using the following scales: quality of life assessment (QOL), modified Ashworth scale, Functional Assessment Classification, FAC, Activities of daily living (ADL), Spinal Cord Independence Measure (SCIM), evaluation of muscle strength on Medical Re-search Council, MRC, scale, evaluation of American Spinal Injury Association Impairment Scale (AIS). Results: The patient benefited from a complex program of neuro-muscular rehabilitation, hav-ing a favorable evolution with an improving score of the evaluating scales and finally gaining his gait balance, including ascending and descending stairs (instrumentally assisted for left plan-tar dorsiflexion movement with orthosis walking). At discharge the patient’s neurological defi-cit was reclassified as AIS D paraplegia, with the neurogenic bladder and bowel having been remitted. Discussions: The disc herniation at L3 level generated a cauda equina syndrome, which initially generated a paraplegia. When the inflammation remitted it became clear that the left L4 root was affected, with a complete deficit of plantar dorsiflexion. In conclusion it was not a case of spinal cord syndrome (as the spinal cord ends at L2 level) or conus medullaris syndrome. Conclusions: The interdisciplinary therapeutic approach together with a specific, customized re-habilitation program for a patient with AIS C paraplegia after a surgically treated disc hernia is successfully improving the neuromuscular deficit and upgrading the patient's quality of life. Keywords: rehabilitation, disc hernia, low back pain, paraplegia

Prevalence of Lumbar Disk Herniation in Adult Patients with Low Back Pain Based in Magnetic Resonance Imaging Diagnosis

Background: Lumbar disc degenerative disease has now been proven as the most common cause of low back pain throughout the world. Approximately 5–15% of patients with low back pain suffer from lumbar disc herniation. Presenting symptoms of lumbar disc degeneration are lower back pain and sciatica which may be aggravated by walking, sitting, standing, bending, lifting etc. Aim: To evaluate based on MRI images the prevalence of LDH in patients with low back pain and its correlation between various demographic data. Methods: This Cross sectional and observational study was conducted from January 2016 to December 2017 at department of Imagery in the University Hospital Center `Mother Theresa`. During the two years’ period of this study, 342 patients of low back pain were presented to department of imagery suspected for lumbar disc herniation. Diagnostic criteria were based upon abnormal findings in MRI. All MRI scans were obtained with 1.5 tesla MRI machine. Data analysis was carried out with SPSS software for Windows version 20.0. Results: Overall 342 patients with LBP came into Imagery department, the prevalence of lumbar disc herniation resulted 31.9% (109/342). Most of patients 60.5% were presented with continuous LBP with a predominance of deterioration of pain by the walking activity 65.2%. The average age of patients with LDH resulted 51.12 years old with min 32 years and max 74 years old. The ratio M:F of LDH patients resulted 1.4, with predominance of males 59.6%. The active age 40-49 years (28.9%) old and 50-59 years (36.9%) were the most affected by LDH compared to other age groups. Based on MRI images disc herniation was most commonly present at the level of L3/L4 and L4/L5. Commonest types of disc herniation were protrusion 63.3% (69/109) followed by extrusion 21.1% (23/109). In the overall multivariate regression analysis, a significant relation between lumbar disk herniation and some of occupation was found (p˂0.05) Conclusions: Biologically, the lumbar herniation disc is a potential contributor to low back pain. The prevalence of LDH among patients with LBP resulted 31.9%, and men were more prone to suffered from disc herniation than women, due to increased mechanical stress and injury. Results reported the frequent occurrence of lumbar disc degenerative disease in active age. The lumbar discs most often affected and leads to herniation are L3-L4, and L4–L5. Research efforts should endeavor to reduce risk factors and improve the quality of life.

Efficacy and Safety of Condoliase Disc Administration as a New Treatment for Lumbar Disc Herniation

Introduction

Condoliase is a newly approved drug that improves symptoms associated with lumbar disk herniation (LDH) by intradiscal administration. This study aimed to evaluate the mid-term outcomes of condoliase injection, examine the adverse events, including cases that required surgery after condoliase administration, and verify cases in which condoliase could be effective.

Methods

We enrolled patients with LDH who were treated conservatively for at least six weeks and received condoliase. We assessed the visual analog scale (VAS) score, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, Oswestry Disability Index, disk height, and disk degeneration for up to 6 months, and we examined the complications. Furthermore, a 50% or more improvement in leg pain VAS score was considered effective. Factors related to symptom improvement were investigated by determining whether lower limb pain improved in six months.

Results

In total, 84 patients were recruited (52 men, 32 women; mean age, 44.2 ± 17.1 [16-86 years]). The duration of illness was 6.7 ± 6.8 (1.5-30) months. All patient-based outcomes significantly improved at 4 weeks after the administration compared with pretreatment. The intervertebral disc height decreased significantly at four weeks after condoliase administration compared with that before administration. Progression of intervertebral disc degeneration occurred in 50% of the patients. Eleven patients underwent herniotomy due to poor treatment effects. Moreover, treatment in 77.4% of the patients was considered effective. A logistic regression analysis revealed that L5/S1 disk administration (p = 0.029; odds ratio, 5.94; 95% confidence interval, 1.20-29.45) were significantly associated with clinical effectiveness.

Conclusions

Condoliase disk administration improved pain and quality of life over time. Condoliase disk administration was more effective in L5/S1 intervertebral administration.

Low Back Biomechanics during Repetitive Deadlifts: A Narrative Review

OCCUPATIONAL APPLICATIONSHeavy deadlifting is used as a screening tool or training protocol for recruitment and retention in physically-demanding occupations, especially in the military. Spinal loads experienced during heavy deadlifts, particularly shearing forces, are well above recommended thresholds for lumbar spine injury in occupational settings. Although members of the noted occupation likely have stronger musculoskeletal systems compared to the general population, experiencing shearing forces that are 2 to 4 times larger than the threshold of injury, particularly under repetitive deadlift, may transform a screening tool or training protocol to an occupationally-harmful physical activity.

Low Back Biomechanics during Repetitive Deadlifts: A Narrative Review

OCCUPATIONAL APPLICATIONSHeavy deadlifting is used as a screening tool or training protocol for recruitment and retention in physically-demanding occupations, especially in the military. Spinal loads experienced during heavy deadlifts, particularly shearing forces, are well above recommended thresholds for lumbar spine injury in occupational settings. Although members of the noted occupation likely have stronger musculoskeletal systems compared to the general population, experiencing shearing forces that are 2 to 4 times larger than the threshold of injury, particularly under repetitive deadlift, may transform a screening tool or training protocol to an occupationally-harmful physical activity.

Characteristics of lumbar disc degeneration and risk factors for collapsed lumbar disc in Korean farmers and fishers

Background

Few studies have investigated the risk factors for lumbar intervertebral disc degeneration among hard physical workers involved in heavy lifting. In this study, we aimed to identify the characteristics of lumbar intervertebral disc degeneration and evaluate the relationship between collapsed lumbar disc and potential risk factors in farmers and fishers.

Methods

This study included 203 farmers (103 men and 100 women) and 166 fishers (95 men and 71 women) aged 40–69 years who had undergone lumbar magnetic resonance imaging and were enrolled in the Korea Farmer's Knee Cohort and the Jeonnam Fishers' Cohort. We evaluated each of the 5 lumbar discs using the Pfirrmann grading system and classified collapsed lumbar intervertebral disc (cLD) as a case with ≥ 1 grade 5 at any disc level. We investigated potential risk factors, such as gender, age, body mass index (BMI), working hours per day, working months per year, and cumulative heavy lifting working time (CLWT). The odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were calculated.

Results

The prevalence of cLD was 19.8% (23.7% among fishers, 21.2% among fishers with farming, and 17.2% among farmers). cLD correlated with factors such as age and occupation. Gender, CLWT and the working time matrix were not significantly associated with cLD. The OR of cLD adjusted by gender, age, BMI, and working time matrix was 1.26 (95% CI: 0.69–2.30) for ≥ 5,000 hours CLWT compared to that for < 2,000 hours CLWT. The OR of cLD adjusted by gender, age, BMI, CLWT, and working time matrix was 2.08 (95% CI: 1.06–4.06) for fishers compared to that for farmers.

Conclusions

Heavy lifting did not show a significant association with cLD in farmers and fishers. However, there is possibility that fishers are at a higher risk of lumbar disc collapse than farmers.

Predictors of the conservative management outcomes in patients with lumbar herniated nucleus pulposus: A prospective study in Indonesia

BACKGROUND

The objective of this study was to identify the predictors of the conservative management outcomes in patients with lumbar herniated nucleus pulposus (HNP).

METHODS

A prospective study was conducted between June 2010 and April 2012 in Banda Aceh, Indonesia. Clinical and baseline neurologic examinations such as passive straight leg raising test (SLRT), cross SLRT, and patellar and Achilles reflexes were assessed prior to the conservative management. The patients were evaluated at 2nd, 4th, 8th, 12th and 24th week following commencement of the conservative management.

RESULTS

We recruited and followed 171 HNP patients of which 35.7% of them had good outcome. At univariate analysis, patients with more than 12 months duration of complaint, those with dominant radicular pain, severe pain intensity (visual analogue scale 7-10), positive SLRT, positive cross SLRT, and reduced motor power of knee extensors (muscle strength grade 1-4), were associated with poor outcome. Multivariate analysis suggested that patients with dominant radicular type of pain were likely to had poor outcome compared to those with dominant back pain (odd ratio (OR) 10.57 with 95% confidence interval (CI) 1.15-96.93). Patients with reduced motor power of knee extensors also had a higher chance to have poor outcome compared to those who were normal (OR: 10.57; 95% CI: 1.15-96.93).

CONCLUSION

Type of pain and the strength of lower extremities could be able to predict the failure of conservative management in patients with lumbar disc herniation. However, further studies with the bigger sample size are warrant to validate our results.

Risk Factors of Intervertebral Disc Pathology-A Point of View Formerly and Today-A Review

Intervertebral disc pathology is a common disorder that can be caused by genetic, mechanical, and behavioral factors; however, it is possible to slow its progression. Although environmental and behavioral factors were previously considered to be the sole causes of intervertebral disc pathologies such as disc herniation, recent studies have shown that genetic factors also play an important role. This review compares the perception of major risk factors from the last and present centuries. It also examines individual genetic and non-genetic factors acting as risk factors, as well as some approaches for preventing intervertebral disc pathologies, and compares available statistics regarding disc herniation.

Risk Factors for Recurrent L4-5 Disc Herniation After Percutaneous Endoscopic Transforaminal Discectomy: A Retrospective Analysis of 654 Cases

Background

Percutaneous endoscopic lumbar discectomy (PELD) is an increasingly applied minimally invasive procedure that has several advantages in the treatment of lumbar disc herniation (LDH). However, recurrent LDH (rLDH) has become a concerning postoperative complication. It remains difficult to establish a consensus and draw reliable conclusions regarding the risk factors for rLDH.

Purpose

This retrospective study aimed to investigate the risk factors associated with rLDH at the L4-5 level after percutaneous endoscopic transforaminal discectomy (PETD).

Methods

A total of 654 patients who underwent the PETD procedure at the L4-5 level from October 2013 to January 2020 were divided into a recurrence (R) group (n=46) and a nonrecurrence (N) group (n=608). Demographic and clinical data and imaging parameters were collected and analyzed using univariate and multiple regression analyses.

Results

The current study found a 7% rate of rLDH at the L4/5 level after successful PETD. Univariate analysis showed that older age, high BMI, diabetes mellitus history, smoking, large physical load intensity, moderate disc degeneration, small muscle-disc ratio (M/D), more fat infiltration, large sagittal range of motion (sROM), scoliosis, small disc height index (DHI), small intervertebral space angle (ISA), and small lumbar lordosis (LL) were potential risk factors (P < 0.10) for LDH recurrence after PETD at the L4-5 level. Multivariate analysis suggested that high BMI, large physical load intensity, moderate disc degeneration, small M/D, more fat infiltration, large sROM, small ISA, and small LL were independent significant risk factors for recurrence of LDH after PETD.

Conclusion

Consideration of disc degeneration, M/D, fat infiltration of the paravertebral muscles, sROM, ISA, LL, BMI, and physical load intensity prior to surgical intervention may contribute to the prevention of rLDH following PETD and lead to a more satisfactory operative outcome and the development of a reasonable rehabilitation program after discharge.

Medical students vs general public awareness regarding disc prolapse in Jeddah

BACKGROUND

Disc herniation is a condition where tearing occurs in the outer annular layer of the intervertebral pad leading the inner gel-like material to bulge ouwards the spinal cord, due to the high load of the vertebrae. This will produce back pain and symptoms in different sites according to the level of the herniation in the vertebral column.

AIM

To compare the level of awareness regarding disc herniation among the general population and medical students in Jeddah.

METHODOLOGY

A descriptive cross-sectional study was conducted through an electronic questionnaire to assess the level of awareness regarding disc prolapse among the general population and medical students in Jeddah. The questionnaire was in the Arabic language, it was taken and validated by the previous study which took place in Taif.

RESULTS

Our studied sample involved 1026 individuals aged between 11 and 99 years, with a mean age of 34.03 ± 13.28 years old. More than half of the respondents were female (55.4%), most of them were Saudi nationals (90.1%), and most of them have received a higher education (67.7%). Results showed that 54.1% of the general population and 77.7% of medical students reported good knowledge regarding this condition.

CONCLUSION

This study revealed that the level of awareness regarding disc prolapse among the general population and medical students was poor in some respects such as: knowledge about the preventive measures, symptoms of the disease, the most common site in the spine affected by the disease, and the gold standard imaging method to diagnose this disease.

Lumbar stability following graded unilateral and bilateral facetectomy: A finite element model study

BACKGROUND

Excision of excessive amount of facet joint during lumbar discectomy or decompression can cause segmental instability of the lumbar spine. This study was performed to assess the segmental instability, facet joint loading and intradiscal pressure following graded lumbar facetectomy. This biomechanical study was performed using a verified and validated L3-S1 finite element model.

METHODS

Nine scenarios were analysed. Intact model as control, 30%, 45%, 60% and complete facet joint excision in unilateral and bilateral setting. The effect of progressive graded facetectomy of L4-L5 on the segmental mobility, facet loading and intradiscal pressure was assessed.

FINDINGS

In comparison with control 30% excision of the facet joint mainly caused increase in mediolateral mobility. With 45% excision of the facet joint there was increase in both anteroposterior and mediolateral mobility, this was worse in bilateral and unilateral models respectively. This worsened with larger facet excision scenarios. Facet load increased significantly on extension with excision of 45% & 60% unilaterally and 100% bilaterally. Flexion produced rise in intradiscal pressure in all scenarios.

INTERPRETATION

The increased spinal mobility, facet loading and intradiscal pressure with more than 30% facetectomy highlights the importance of preserving the facets during decompression thereby safeguarding accelerated degeneration of these segments and iatrogenic segmental instability. The findings from this study could also potentially explain the correlation between spinal instability, disc degeneration and facet joint arthrosis as noted in clinical studies.

Current perspectives on the role of biomechanical loading and genetics in development of disc degeneration and low back pain; a narrative review

Degenerative changes in the disc have long been of interest; they are thought to be strongly associated with low back pain and caused by inappropriate loading or through injury. However, independent of the magnitude of occupational spinal loading, twin studies find that the heritability of lumbar disc degeneration is 34-74%. This finding has led to intensive searches for susceptibility genes; some genes associated with disc degeneration have been identified, though all with small effects on the degenerative process. The complex nature of degenerative changes suggests that many different genes are involved, and that interactions with environmental factors are influential in progression of degeneration. Low back pain itself also appears heritable (30-46%). The most important clinical question though, is not how discs degenerate but is disc degeneration related to low back pain. Imaging studies find many people with degenerate discs or even with discs showing pathological features such as herniations, are asymptomatic. However results are obscured by the lack of consistent definitions of the phenotypes of disc degeneration and of low back pain. Epidemiological studies could help disentangle these complex relationships, but they will only be successful once consistent classifications and phenotypes of both disc degeneration and low back pain are developed.

The roles of lumbar load thresholds in cumulative lifting exposure to predict disk protrusion in an Asian population

Background

The purpose of this study was to determine whether a specific threshold per lifting movement, the accumulation above which best predicts lumbar disk protrusion, exists or the total lifting load should be considered.

Methods

This was a retrospective study. Subjects with various lifting exposures were recruited. Disk protrusion was assessed by magnetic resonance imaging. The cumulative lifting load was defined as the sum of the time-weighed lumbar load for each job and was calculated using a biomechanical software system. The effectiveness of accumulation above different thresholds in predicting disk protrusion were compared using four statistical methods.

Results

A total of 252 men and 301 women were included in the final analysis. For the men, 3000 Newtons for each lifting task was the optimal threshold for predicting L4-S1 disk protrusion, whereas for the women, 2800 Newtons was optimal.

Conclusions

Our findings suggested that for cumulative lifting exposure, including the total lifting load without defining a minimal exposure limit might not be the optimal method for predicting disk protrusion. The NIOSH 3400 Newton recommended limits do not appear to be the optimal thresholds for preventing disk protrusion. Different lifting thresholds might be needed for men and women in the workplace for their safety.

The association between occupational loading and spine degeneration on imaging - a systematic review and meta-analysis

Background

There are inconsistencies in findings regarding the relationship of occupational loading with spinal degeneration or structural damage. Thus, a systematic review was conducted to determine the current state of knowledge on the association of occupational loading and spine degeneration on imaging.

Methods

We performed electronic searches on MEDLINE, CINAHL and EMBASE. We included cross-sectional, case control and cohort studies evaluating occupational loading as the exposure and lumbar spine structural findings on imaging as the outcomes. When possible, results were pooled.

Results

Seventeen studies were included in the review. Ten studies evaluated the association of occupational loading with disc degeneration (signal intensity), four of which were pooled into a meta-analysis. Of the 10 studies, only two did not identify a relationship between occupation loading and disc degeneration. A meta-analysis including four of the studies demonstrated an association between higher loading and degeneration for all spinal levels, with odds ratios between 1.6 and 3.3. Seven studies evaluated disc height narrowing and seven evaluate disc bulge, with six and five identifying an association of loading and with imaging findings respectively. Three studies evaluated modic changes and one identified and association with occupational load.

Conclusions

There was moderate evidence suggesting a modest association between occupational loading and disc degeneration (signal intensity), and low-quality evidence of an association between occupational loading and disc narrowing and bulging.

Occupational lifting predicts hospital admission due to low back pain in a cohort of airport baggage handlers

Purpose

To examine if occupational lifting assessed as cumulative years as a baggage handler is associated with first-time hospital diagnosis or treatment for low back disorders.

Methods

This study is based on the Copenhagen Airport Cohort consisting of male baggage handlers performing heavy lifting every day and a reference group of unskilled men from the greater Copenhagen area during the period 1990–2012. We followed the cohort in the National Patient Register and Civil Registration System to obtain information on diagnoses, surgery, mortality, and migration. The outcomes were first-time hospital diagnosis or surgery for (1) lumbar disc herniation or (2) low back pain (LBP).

Results

Baggage handlers (N = 3473) had a higher incidence rate of LBP, but not of lumbar disc herniation, compared to the reference group (N = 65,702). Baggage handlers with longer employment had a higher incidence of LBP compared to baggage handlers with shorter employment. The linear association of cumulative years as a baggage handler on LBP was significantly increased with an incidence rate ratio of 1.16 (95% CI 1.07–1.25) for a 5-year increase of employment as baggage handler.

Conclusions

In this large cohort study, we found an increased incidence of LBP among baggage handlers compared to the reference group with indications of a dose–response relationship between years of employment and the outcome. For baggage handlers working on the apron, the incidence was particularly increased before introduction of technical lifting equipment, suggesting that preventive measures to reduce cumulative work load may have a positive effect.

Predictors of Successful Outcomes of Selective Nerve Root Blocks for Acute Lumbar Disc Herniation

STUDY DESIGN

Prospective, observational cohort study.

OBJECTIVE

Selective nerve root block (SNRB) is an effective, standard interventional procedure for failed medical management in lumbar disc herniation (LDH). However, the factors that would predict successful outcomes in patients undergoing SNRB have not been clearly studied.

METHODS

Patients with failed conservative treatment for acute LDH, treated with SNRB were periodically followed till 1 year. Patients who failed to have pain relief or had recurrent pain after SNRB, underwent surgery. The pattern of radiculogram during SNRB was classified into 4 types-"arm," "arrow," "linear," and "splash." Various clinical factors, radiological factors, and radiculograms were compared between patients who had consistent pain relief (group A) and those patients who did not (group B).

RESULTS

A total of 91 patients underwent SNRB. Sixty-nine had good pain relief maintained till 1 year (75.8% success). Twenty-two patients underwent surgery after failed NRB at a mean of 6.3 weeks. Patients with sensory symptoms (P = .01), higher mean preinjection Oswestry Disability Index (ODI) score (P = .02), higher mean postinjection ODI score at 3 weeks (P = .004), nonmanual job (P = .01), lumbosacral transitional segment (P = .00 005), and splash pattern of radiculogram (P = .005) were predictive of failed NRB. Logistic regression analysis showed that lumbosacral transitional segment at the level of LDH is the most significant factor predicting poor outcome.

CONCLUSIONS

SNRB is an effective technique to provide consistent symptom relief at least till 1 year in patients with acute LDH. The study identified several factors that predicted poor outcomes of SNRB and such patients can be forewarned about need for later surgery.

Comparison of the risk of developing lumbar herniated intervertebral disc between dentists and other occupations: A nationwide population-based study in Taiwan

OBJECTIVES

Dentists may have a higher risk of developing lumbar herniated intervertebral disc (HIVD) due to prolonged sitting and improper postures during work. We conducted this study to delineate this issue, which is still unclear.

METHODS

This nationwide population-based study was conducted using Taiwan National Health Insurance Research Database. We identified 10 734 dentists, 72 066 non-dentist health-care providers (HCPs), and an identical number of age- and gender-matched participants from the general population. The risk of developing lumbar HIVD among dentists, non-dentist HCPs, and general population was compared by tracing their medical histories between 2007 and 2011.

RESULTS

The cumulative incidence rate of lumbar HIVD among dentists during the 5-year follow-up period was 1.40%. After adjusting for age, gender, and comorbidities, the risk of developing lumbar HIVD was found to be lower among dentists than that among the general population (adjusted odds ratio [AOR]: 0.80, 95% confidence interval [CI]: 0.64-1.00) and non-dentist HCPs (AOR: 0.81, 95% CI: 0.68-0.96).

CONCLUSIONS

Dentists in Taiwan have a lower risk of developing lumbar HIVD than that among other occupations. Although this result is different from the general cognition, it does not imply that the prevention of lumbar HIVD in dentists is not important. Further studies are warranted to better address this issue.

Work-related risk factors for sciatica leading to hospitalization

The aim of this study was to assess the effects of the general strenuousness of work and various physical exposures on the risk of hospitalization for sciatica. The study population consisted of Finns aged 30 to 59 who had participated in a national health examination survey in 1978–80 (N = 3891). The participants were followed up until the end of 2011 and information on work-related determinants was acquired by a questionnaire. After adjustment for confounders, sedentary work involving handling fairly heavy objects/physically light work (HR 1.57; 95% CI 1.05–2.34), lifting or carrying heavy objects (2.10; 1.35–3.26) and exposure to whole-body vibration (1.61; 0.95–2.72) predicted sciatica, whereas heavier workloads appeared to reduce its risk (0.48; 0.26–0.89). There was an interaction between body mass index and exposure to whole-body vibration for the risk of sciatica. Overweight (1.94; 0.96–3.93) and obese (3.50; 1.44–8.46) participants exposed to whole-body vibration were at an increased risk of sciatica. Individuals of normal weight who were exposed to vibration, and overweight and obese individuals who were not exposed to vibration were not at an increased risk. The risk of hospitalization for sciatica seems to be highest among obese individuals exposed to whole-body vibration and among those lifting or carrying heavy objects.

Work-relatedness of lumbosacral radiculopathy syndrome: Review and dose-response meta-analysis

OBJECTIVE

Clinicians need to know whether lumbosacral radiculopathy syndrome (LRS) can be attributed to work. This review describes what work-related risk factors are associated with LRS.

METHODS

A systematic review was performed in PubMed and Embase. Inclusion criteria were that LRS was diagnosed by a clinician and workers exposed to work-related risk factors were compared to workers less or not exposed. A quality assessment and a meta-analysis were performed, including a dose-response analysis.

RESULTS

The search resulted in 7,350 references and 24 studies that fulfilled the inclusion criteria: 19 studies were rated as having a high risk of bias and 5 as having a low risk of bias. The median number of LRS patients per study were 209 (interquartile range 124-504) and the total number of participants was 10,142. The meta-analysis revealed significant associations with heavy physically demanding work (odds ratio [OR] 2.03, 95% confidence interval [CI] 1.48-2.79), bending or twisting of the trunk (OR 2.43, 95% CI 1.67-3.55), and lifting and carrying in combination with bending or twisting of the trunk (OR 2.84, 95% CI 2.18-3.69). No significant associations were found for professional driving (OR 1.46, 95% CI 0.90-2.35) or sitting (OR 1.08, 95% CI 0.49-2.38). A dose-response relation was present per 5 years of exposure for bending (OR 1.12, 95% CI 1.04-1.20), lifting (OR 1.08, 95% CI 1.02-1.14) and the combination of bending and lifting (OR 1.14, 95% CI 1.01-1.29).

CONCLUSIONS

Moderate to high-quality evidence is available that LRS can be classified as a work-related disease depending on the level of exposure to bending of the trunk or lifting and carrying. Professional driving and sitting were not significantly associated with LRS.

Higher Risk of Intervertebral Disc Herniation among Neurosurgeons Than Neurologists: 15 Year-Follow-Up of a Physician Cohort

High physical activity or workload has been associated with intervertebral disc degeneration. However, there is little data on physicians' risks of disc disease. The study aimed to investigate the incidences of spinal problems among neurologists and neurosurgeons. A cohort of neurologists and neurosurgeons was derived from Taiwan's national research database. During the study period, the incidences of intervertebral disc herniation or spondylosis among these specialists were calculated. Another one-to-one by propensity score matched cohort, composed of neurologists and neurosurgeons, was also analyzed. A Cox regression hazard ratio (HR) model and Kaplan-Meier analysis were conducted to compare the risks and incidences. The entire cohort comprised 481 and 317 newly board-certified neurologists and neurosurgeons, respectively. During the 15 years of follow-up, neurosurgeons were approximately six-fold more likely to develop disc problems than neurologists (crude HR = 5.98 and adjusted HR = 6.08, both p < 0.05). In the one-to-one propensity-score matched cohort (317 neurologists versus 317 neurosurgeons), there were even higher risks among neurosurgeons than neurologists (crude HR = 8.15, and adjusted HR = 10.14, both p < 0.05). Neurosurgeons have a higher chance of intervertebral disc disorders than neurologists. This is potentially an occupational risk that warrants further investigation.

Exposure to whole-body vibration and hospitalization due to lumbar disc herniation

Objective

The aim was to examine if exposure to whole-body vibration (WBV) increases the risk for hospitalization due to lumbar disc herniation.

Methods

The study basis is a cohort of 288,926 Swedish construction workers who participated in a national occupational health surveillance programme from 1971 until 1992. Job title, smoking habits, body weight, height and age were registered at the examinations. Assessment of WBV were made for each of the constituent occupations by constructing a job-exposure matrix (JEM). Exposure to WBV was graded on a scale from 0 to 5. In addition, the occurrence of hospitalization due to lumbar disc herniation from January 1st 1987 until December 31st 2010 was collected from a linkage with the Swedish Hospital Discharge Register. Poisson regressions were used to estimate relative risk with 95 percent confidence intervals (95% CI), adjusting for age, height, weight and smoking, using white-collar workers and foremen as a reference group.

Results

There was an increased risk for hospitalization due to lumbar disc herniation for workers in the construction industry exposed to medium to high WBV compared to white-collar workers and foremen 1.35 (1.12–1.63). When restricting the analyses to include workers 30–49 years of age at the time of the hospital admission the risk was 1.69 (95% CI 1.29–2.21).

Conclusion

This study further supports that occupational exposure to whole-body vibration increases the risk for hospitalization due to lumbar disc herniation.

Electronic supplementary material

The online version of this article (10.1007/s00420-018-1316-5) contains supplementary material, which is available to authorized users.

Do Technical Aids for Patient Handling Prevent Musculoskeletal Complaints in Health Care Workers?-A Systematic Review of Intervention Studies

The physical load ensuing from the repositioning and moving of patients puts health care workers at risk of musculoskeletal complaints. Technical equipment developed to aid with patient handling should reduce physical strain and workload; however, the efficacy of these aids in preventing musculoskeletal disorders and complaints is still unclear. A systematic review of controlled intervention studies was conducted to examine if the risk of musculoskeletal complaints and disorders is reduced by technical patient handling equipment. MEDLINE®/PubMed®, EMBASE®, Allied and Complementary Medicine Database (AMED), and Cumulative Index of Nursing and Allied Health Literature (CINAHL®) were searched using terms for nursing, caregiving, technical aids, musculoskeletal injuries, and complaints. Randomized controlled trials and controlled before-after studies of interventions including technical patient handling equipment were included. The titles and abstracts of 9554 publications and 97 full-texts were screened by two reviewers. The qualitative synthesis included one randomized controlled trial (RCT) and ten controlled before-after studies. A meta-analysis of four studies resulted in a pooled risk ratio for musculoskeletal injury claims (post-intervention) of 0.78 (95% confidence interval 0.68-0.90). Overall, the methodological quality of the studies was poor and the results often based on administrative injury claim data, introducing potential selection bias. Interventions with technical patient handling aids appear to prevent musculoskeletal complaints, but the certainty of the evidence according to GRADE approach ranged from low to very low.

A Microstructural Investigation of Disc Disruption Induced by Low Frequency Cyclic Loading

STUDY DESIGN

Microstructural investigation of low frequency cyclic loading and flexing of the lumbar disc.

OBJECTIVE

To explore micro-level structural damage in motion segments subjected to low frequency repetitive loading and flexing at sub-acute loads.

SUMMARY OF BACKGROUND DATA

Cumulative exposure to mechanical load has been implicated in low back pain and injury. The mechanical pathways by which cyclic loading physically affects spine tissues remain unclear, in part due to the absence of high quality microstructural evidence.

METHODS

The study utilized seven intact ovine lumbar spines and from each spine one motion segment was used as a control, two others were cyclically loaded. Ten motion segments were subjected to 5000 cycles at 0.5 Hz with a peak load corresponding to ∼30% of that required to achieve failure. An additional small group of segments subjected to 10,000 or 30,000 cycles was similarly analyzed. Following chemical fixation and decalcification samples were cryosectioned along one of the oblique fiber angles and imaged in their fully hydrated state using differential interference contrast optical microscopy. Structural damage obtained from the images was organized into an algebraic shell for analysis.

RESULTS

At 5000 cycles the disc damage was limited to inner wall distortions, evidence of stress concentrations at bridging-lamellae attachments, and small delaminations. The high-cycle discs tested exhibited significant mid-wall damage. There was no evidence of nuclear material being displaced.

CONCLUSION

At this low frequency and without the application of sustained loading or a more severe loading regime, or maintaining a constant flexion with repetitive loading, it seems unlikely that actual nuclear migration occurs. It is possible that the inner-annular damage shown in the low dose group could disrupt pathways for nutrient diffusion leading to earlier cell death and matrix degradation, thus contributing to a cascade of degeneration.

LEVEL OF EVIDENCE

N/A.

Cumulative Mass and NIOSH Variable Lifting Index Method for Risk Assessment: Possible Relations

Objective The aim of this study was to explore whether the Variable Lifting Index (VLI) can be corrected for cumulative mass and thus test its efficacy in predicting the risk of low-back pain (LBP). Background A validation study of the VLI method was published in this journal reporting promising results. Although several studies highlighted a positive correlation between cumulative load and LBP, cumulative mass has never been considered in any of the studies investigating the relationship between manual material handling and LBP. Method Both VLI and cumulative mass were calculated for 2,374 exposed subjects using a systematic approach. Due to high variability of cumulative mass values, a stratification within VLI categories was employed. Dummy variables (1-4) were assigned to each class and used as a multiplier factor for the VLI, resulting in a new index (VLI_CMM). Data on LBP were collected by occupational physicians at the study sites. Logistic regression was used to estimate the risk of acute LBP within levels of risk exposure when compared with a control group formed by 1,028 unexposed subjects. Results Data showed greatly variable values of cumulative mass across all VLI classes. The potential effect of cumulative mass on damage emerged as not significant ( p value = .6526). Conclusion When comparing VLI_CMM with raw VLI, the former failed to prove itself as a better predictor of LBP risk. Application To recognize cumulative mass as a modifier, especially for lumbar degenerative spine diseases, authors of future studies should investigate potential association between the VLI and other damage variables.

Evaluation of spinal posture using Microsoft Kinect™: A preliminary case-study with 98 volunteers

This work proposes a novel approach to assess spinal curvature, by using Microsoft's Kinect™ to obtain 3D reconstructed models of subject's dorsal skin surface in different postures. This method is non-invasive, radiation-free and low-cost. The trial tests here presented intended to evaluate the reliability of this approach, by assessing the tendency of 98 volunteers to present scoliosis. The shoulder height difference was calculated for each subject's scan, by quantifying the angular slope of a line crossing both scapulae. The volunteers' average age was 24.7 years. Results showed that 68.37% of the volunteers revealed differences higher than 1° between the shoulders, having that their record in what concerns to loads and lesions proved to increase the angular slope. This initial approach shall establish the grounds for assessing spinal posture in pre-clinical or industrial ergonomics scans. Further studies shall include comparison versus traditional imaging methods and experienced clinical evaluation.

An epidemiological surveillance network of lumbar disc surgery to help prevention of and compensation for low back pain

BACKGROUND

In the context of the establishment of a new surveillance system, the aim was to assess the proportion of cases of lumbar disc surgery (LDS) attributable to work according to occupation category and industry sector.

METHODS

The sociodemographic and socioeconomic data of 3150 inpatients living in a French region discharged in 2007-2008 from spine centers of the region following LDS were compared with those of the regional population. Occupational history was gathered using a mailed questionnaire. The attributable fraction of risk for exposed individuals (AFE) and population attributable fraction of risk (PAF) were calculated in relation to occupations and industries.

RESULTS

Three occupational subcategories presented an AFE >50% for men (police and armed forces, unskilled agricultural and skilled craft blue-collar workers). There were eight subcategories for women, including material handlers and related equipment workers, and skilled industrial and unskilled agricultural blue-collar workers. The PAF for men was highest for construction and for women it was highest for wholesale and retail trades.

CONCLUSION

The AFE and PAF are valuable for public policy. Although PAF could be used to help public health policy makers to implement preventive measures, the AFE could assist expert tribunals who take decisions about compensation for occupational diseases.

Characterizing the combined effects of force, repetition and posture on injury pathways and micro-structural damage in isolated functional spinal units from sub-acute-failure magnitudes of cyclic compressive loading

BACKGROUND

Previous research suggests that when the magnitude of peak compressive force applied during cyclic loading exceeds 30% of a functional spinal unit's estimated ultimate compressive tolerance, fatigue failure of the cartilaginous endplate or vertebra will occur before intervertebral disc herniation.

METHODS

Three levels of peak compressive force, three cycle rates and two dynamic postural conditions were examined using a full-factorial design. Cyclic compressive force was applied using a modified material testing apparatus, in accordance with a biofidelic time-varying waveform with synchronous flexion/extension rotation for 5000 cycles. Annulus fibrosus tissue from 36 "survivor" FSUs was excised for histological analysis.

RESULTS

80% of specimens survived 5000 cycles of cyclic loading. A marked difference of the magnitude of peak compressive force was noted in the Kaplan-Meier survival function of experimental conditions that induced fatigue injury. Overall, in the 40% ultimate compressive tolerance load condition, the probability of survival was less than 67%. The micro-structural damage detected in excised samples of annulus fibrosus tissue consisted of clefts and fissures within the intra-lamellar matrix, as well as delamination within the inter-lamellar matrix.

INTERPRETATION

Consistent with previous research, our findings support a threshold of peak compressive force of 30% ultimate compressive tolerance, where cyclic loading above this level will likely result in fatigue injury in less than 5000 cycles of in vitro mechanical loading. However, findings from our histological analyses demonstrate that considerable micro-structural damage occurred in specimens that "survived" the cyclic loading exposure.

The dose-response relationship between cumulative lifting load and lumbar disk degeneration based on magnetic resonance imaging findings

BACKGROUND

Lumbar disk degeneration (LDD) has been related to heavy physical loading. However, the quantification of the exposure has been controversial, and the dose-response relationship with the LDD has not been established.

OBJECTIVE

The purpose of this study was to investigate the dose-response relationship between lifetime cumulative lifting load and LDD.

DESIGN

This was a cross-sectional study.

METHODS

Every participant received assessments with a questionnaire, magnetic resonance imaging (MRI) of the lumbar spine, and estimation of lumbar disk compression load. The MRI assessments included assessment of disk dehydration, annulus tear, disk height narrowing, bulging, protrusion, extrusion, sequestration, degenerative and spondylolytic spondylolisthesis, foramina narrowing, and nerve root compression on each lumbar disk level. The compression load was predicted using a biomechanical software system.

RESULTS

A total of 553 participants were recruited in this study and categorized into tertiles by cumulative lifting load (ie, <4.0 × 10(5), 4.0 × 10(5) to 8.9 × 10(6), and ≥8.9 × 10(6) Nh). The risk of LDD increased with cumulative lifting load. The best dose-response relationships were found at the L5-S1 disk level, in which high cumulative lifting load was associated with elevated odds ratios of 2.5 (95% confidence interval [95% CI]=1.5, 4.1) for dehydration and 4.1 (95% CI=1.9, 10.1) for disk height narrowing compared with low lifting load. Participants exposed to intermediate lifting load had an increased odds ratio of 2.1 (95% CI=1.3, 3.3) for bulging compared with low lifting load. The tests for trend were significant.

LIMITATIONS

There is no "gold standard" assessment tool for measuring the lumbar compression load.

CONCLUSIONS

The results suggest a dose-response relationship between cumulative lifting load and LDD.

A cohort study of sciatic pain and measures of internal spinal load in professional drivers

In a prospective cohort study of 537 male professional drivers, the occurrence of sciatic pain showed stronger associations with measures of internal lumbar load expressed in terms of daily compressive dose, S(ed) (MPa), and risk factor, R (non-dimensional), according to ISO/WD 2631-5 (2013), than with measures of daily vibration exposure calculated as either 8-h energy-equivalent frequency-weighted acceleration (ms(-2) r.m.s.) or vibration dose value (ms(-1.75)) according to the EU Directive on mechanical vibration (2002). Herniated lumbar disc, previous lumbar trauma and physical work load were also powerful predictors of the occurrence of sciatic pain over time. Psychosocial work environment was poorly associated with sciatic pain. The boundary values of risk factor (R) for low and high probabilities of adverse health effects on the lumbar spine, as proposed by international standard ISO/WD 2631-5 (2013), tend to underestimate the health risk in professional drivers.

PRACTITIONER SUMMARY

In a prospective cohort study of professional drivers, measures of internal spinal load were better predictors of the occurrence of sciatic pain than the measures of daily vibration exposure established by the EU Directive (2002). Herniated lumbar disc, lumbar trauma and physical work load were also associated with sciatic pain.

Changes in the spinopelvic parameters of elite weight lifters

OBJECTIVE

To describe the changes in the spinopelvic parameters in weight lifters and evaluate the factors leading to spinal anatomical changes (eg, spondylolysis and listhesis).

DESIGN

Case-control study.

SETTING

Tertiary, institutional.

PARTICIPANTS

The study group participants were practicing weight lifters in the athletes' village of the 2012 London Olympics. A total of 21 elite weight lifters were enrolled. Their data were compared with those of 45 healthy volunteers in the control group.

INTERVENTIONS

Comparative radiological evaluations were performed among the 21 elite weight lifters. Spinopelvic parameters (radiographic analysis), including total (TLL), upper (ULL), and lower (LLL) lumbar lordoses, sacral slope, pelvic tilt (PT) and incidence, lumbar index, and disc angles, were assessed.

MAIN OUTCOME MEASURES

The proportional ratio of ULL and LLL to TLL (ULL/TLL and LLL/TLL) was measured to describe the proportion effect. These values were compared with those of the control group. Weight lifters with and those without anatomical changes were subdivided into a deformed and nondeformed group, respectively, and further analyzed for differences. The correlation between these spinal parameters and the amount and duration of weight lifting training was also analyzed.

RESULTS

Anatomical changes in the lumbar spine were seen in 6 weight lifters (28.6%, P = 0.01). The mean TLL, ULL, and LLL values (59.8, 22.6, and 37.2 degrees, respectively) were increased, whereas PT (10.3 degrees) was decreased in the athletes compared with the volunteers (P = 0.001, 0.005, 0.07, and 0.018, respectively). The ULL/TLL was higher in the deformed group than in the nondeformed group (P = 0.036). The duration and amount of weight lifting training were not correlated with the spinopelvic parameters measured in this study.

CONCLUSIONS

The elite weight lifters had increased lumbar lordosis and decreased PT compared with the healthy volunteers. The ULL/TLL ratio may be used as a predictive marker for lumbar deformation.

Matrix metalloproteinase-3, vitamin D receptor gene polymorphisms, and occupational risk factors in lumbar disc degeneration

BACKGROUND

Lumbar disc degeneration (LDD) is a process that begins early in life, contributing to the development of low back pain. LDD is a consequence of a variety of factors, and its etiology remains poorly understood. Objectives to investigate occupational and genetic risk factors inducing lumbar disc degeneration, and to evaluate the possible association of genetic polymorphisms of matrix metalloproteinase 3 (MMP-3) and vitamin D receptor (VDR) with the severity of LDD in an Egyptian population.

SUBJECTS AND METHODS

A case control study involving 84 LDD and 60 controls was carried out. Five types of work related factors were investigated by questionnaire, complete neurological examination for all subjects and MRI for the cases. Polymerase chain reaction and restriction fragment length polymorphism methods were applied to detect polymorphisms in MMP-3 Promoter (-1,171 6A/5A) (rs 731236) and VDR-Apa (rs 35068180).

RESULTS

We found that family history, back injury, smoking, high level of sitting, bending/twisting, physical workload, lifting, whole body vibration, mutant allele 5A of MMP-3 and mutant allele T of VDR were significantly associated with LDD (OR = 2.9, 3.1, 2.1, 11.1, 15.9, 11.7, 8.2, 12.6, 2.5 and 3.1 respectively, p < 0.05). Cases that carry allele 5A and/or allele T were associated with LDD severity.

CONCLUSION

LDD is closely associated in occurrence and severity with occupational, environmental risk factors and susceptibility genes namely MMP-3, and VDR (ApaI). This study throws light on the importance of screening for early detection of susceptible individuals and disease prevention.

Why do some intervertebral discs degenerate, when others (in the same spine) do not?

This review suggests why some discs degenerate rather than age normally. Intervertebral discs are avascular pads of fibrocartilage that allow movement between vertebral bodies. Human discs have a low cell density and a limited ability to adapt to mechanical demands. With increasing age, the matrix becomes yellowed, fibrous, and brittle, but if disc structure remains intact, there is little impairment in function, and minimal ingrowth of blood vessels or nerves. Approximately half of old lumbar discs degenerate in the sense of becoming physically disrupted. The posterior annulus and lower lumbar discs are most affected, presumably because they are most heavily loaded. Age and genetic inheritance can weaken discs to such an extent that they are physically disrupted during everyday activities. Damage to the endplate or annulus typically decompresses the nucleus, concentrates stress within the annulus, and allows ingrowth of nerves and blood vessels. Matrix disruption progresses by mechanical and biological means. The site of initial damage leads to two disc degeneration "phenotypes": endplate-driven degeneration is common in the upper lumbar and thoracic spine, and annulus-driven degeneration is common at L4-S1. Discogenic back pain can be initiated by tissue disruption, and amplified by inflammation and infection. Healing is possible in the outer annulus only, where cell density is highest. We conclude that some discs degenerate because they are disrupted by excessive mechanical loading. This can occur without trauma if tissues are weakened by age and genetic inheritance. Moderate mechanical loading, in contrast, strengthens all spinal tissues, including discs.

Cumulative spine loading and clinically meaningful declines in low-back function

OBJECTIVE

The objective was to assess the role of cumulative spine loading measures in the development of a clinically meaningful decline in low-back function.

BACKGROUND

Cumulative spine loading has been a suspected risk factor for low-back pain for many years, yet the measures that characterize risk have not been well delineated.

METHODS

A total of 56 cumulative exposure measures were collected in a prospective field study of distribution center workers. An individual's risk for a clinically meaningful decline in low-back function (true cases) was explored with daily, weekly, and job tenure cumulative exposure measures using univariate and multivariate statistical modeling techniques. True noncases were individuals with no decline in low-back function.

RESULTS

An individual's risk for a clinically meaningful decline in low-back function (true cases) was predicted well versus true noncases (sensitivity/specificity = 72%/73%) using initial low-back function (p(n)), cumulative rest time, cumulative load exposure, job satisfaction, and worker age.

CONCLUSIONS

Cumulative rest time was identified as an important component for predicting an individual's risk for a clinically meaningful decline in low-back function.

APPLICATION

This information can be used to assess cumulative spine loading risk and may help establish guidelines to minimize the risk of a clinically meaningful decline in low-back function.