Occupational driving as a risk factor for low back pain in active-duty military service members

Primary Creep Characterization in Porcine Lumbar Spine Subject to Repeated Loading

Low back pain (LBP) is a common medical condition worldwide, though the etiology of injuries causing most LBP is unknown. Flexion and repeated compression increase lumbar injury risk, yet the complex viscoelastic behavior of the lumbar spine has not been characterized under this loading scheme. Characterizing the non-injurious primary creep behavior in the lumbar spine is necessary for understanding the biomechanical response preceding injury. Fifteen porcine lumbar spinal units were loaded in repeated flexion-compression with peak compressive stresses ranging from 1.41 to 4.68 MPa. Applied loading simulated real loading exposures experienced by high-speed watercraft occupants. The strain response in the primary creep region was modeled for all tests using a generalized Kelvin-Voigt model. A quasilinear viscoelastic (QLV) approach was used to separate time-dependent (creep) and stress-dependent (elastic) responses. Optimizations between the models and experimental data determined creep time constants, creep coefficients, and elastic constants associated with this tissue under repeated flexion-compression loading. Average R2 for all fifteen models was 0.997. Creep time constants optimized across all fifteen models were 24 s and 580 s and contributed to 20 ± 3% and 30 ± 3% of the overall strain response, respectively. The non-transient behavior contributed to 50 ± 0% of the overall response. Elastic behavior for this porcine population had an average standard deviation of 24.5% strain across the applied stress range. The presented primary creep characterization provides the response precursor to injurious behavior in the lumbar spine. Results from this study can further inform lumbar injury prediction and kinematic models.

The I-PREDICT 50th Percentile Male Warfighter Finite Element Model: Development and Validation of the Thoracolumbar Spine

Military personnel are commonly at risk of lower back pain and thoracolumbar spine injury. Human volunteers and postmortem human subjects have been used to understand the scenarios where injury can occur and the tolerance of the warfighter to these loading regimes. Finite element human body models (HBMs) can accurately simulate the mechanics of the human body and are a useful tool for understanding injury. In this study, a HBM thoracolumbar spine was developed and hierarchically validated as part of the Incapacitation Prediction for Readiness in Expeditionary Domains: an Integrated Computational Tool (I-PREDICT) program. Constitutive material models were sourced from literature and the vertebrae and intervertebral discs were hexahedrally meshed from a 50th percentile male CAD dataset. Ligaments were modeled through attaching beam elements at the appropriate anatomical insertion sites. 94 simulations were replicated from experimental PMHS tests at the vertebral body, functional spinal unit (FSU), and regional lumbar spine levels. The BioRank (BRS) biofidelity ranking system was used to assess the response of the I-PREDICT model. At the vertebral body level, the I-PREDICT model showed good agreement with experimental results. The I-PREDICT FSUs showed good agreement in tension and compression and had comparable stiffness values in flexion, extension, and axial rotation. The regional lumbar spine exhibited "good" biofidelity when tested in tension, compression, extension, flexion, posterior shear, and anterior shear (BRS regional average = 1.05). The validated thoracolumbar spine of the I-PREDICT model can be used to better understand and mitigate injury risk to the warfighter.

Risk factors for low back pain in active military personnel: a systematic review

Purpose

Low back pain (LBP) is prevalent in military personnel. We aimed to systematically review the literature regarding risk factors for first-time LBP during military service among active duty military personnel.

Methods

We searched six electronic databases (inception-April 2020) for randomised controlled trials, cohort studies, and case–control studies published in English in peer-reviewed journals. Eligible studies were independently critically appraised by paired reviewers and a descriptive synthesis was conducted.

Results

We screened 1981 records, reviewed 118 full-text articles, and synthesised data from eight acceptable quality cohort studies. Studies assessed physical (n = 4), sociodemographic (n = 2), and/or occupational factors (n = 5) associated with LBP. Two studies reported prior LBP was associated with a greater than twofold increased risk of LBP compared to those without prior LBP. Other factors consistently associated with LBP included previous musculoskeletal injury (n = 2), less time spent on physical training (n = 2), female sex (n = 2), and lower rank (n = 2). Factors associated with LBP from single studies included marital status, lower education level, blast injury, job duties, and service type. We found inconsistent associations for performance on physical fitness tests, age, and occupation type. Psychological risk factors were not assessed in any included studies.

Conclusion

In active duty personnel, prior history of LBP, previous musculoskeletal injury, less time in physical training, female sex, and lower rank were consistent risk factors for LBP. This information is relevant for researchers, active duty military personnel, and other decision makers. Future studies should explore causal relationships for LBP in this population.

PROSPERO registration number: CRD42018084549.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12998-021-00409-x.

Prevalence of chronic lower back pain in Brazilian military firefighters

Objectives. Lower back pain (LBP) is a common health problem worldwide, affecting an increasing number of individuals. Military firefighters (MFFs) face high levels of physical and psychological demands and are commonly exposed to different occupational risk factors. This study aimed to estimate the prevalence of chronic lower back pain (CLBP) in Brazilian enlisted MFFs. Methods. This cross-sectional study was carried out at the Military Firefighters Department of the Brazilian Federal District (Corpo de Bombeiros Militar do Distrito Federal [CBMDF]). The estimated sample size was 608 MFFs. Results. Of the 623 participants, 575 valid and complete questionnaires were analyzed. A total of 183 participants reported CLBP, indicating a point prevalence of 31.8% (95% confidence interval [CI] [28.2, 35.4]). The prevalence of acute and subacute LBP was 9.2% (95% CI [7.1, 11.9]), and 59% (95% CI [54.9, 62.9]) reported no back pain. CLBP was more common among men aged 40-49 years, who were insufficiently active and overweight. Conclusion. Around one-third of the study population reported CLPB. Prevalence estimates of CLPB were greater among men and those between 40 and 49 years old. Our data support the need for programs to prevent and treat CLBP among firefighters.

Prevalence and Risk Factors for Musculoskeletal Back Injury Among U.S. Army Personnel

INTRODUCTION

Physical and medical readiness have emerged as a top priority in the army over the last decade. With this emphasis on deployment readiness, it is important to understand key risk factors attributed to common medical problems that arise in our soldiers, including low back pain. The purpose of this study is to elucidate demographic and lifestyle risk factors which would result in seeking medical care for musculoskeletal low back pain among active duty army personnel.

MATERIALS AND METHODS

A cross-sectional retrospective study investigating all active duty soldiers between October 1, 2016 and September 30, 2018 was performed using the existing Military Health System Data Repository to retrospectively review administrative claims data. Our study queried 39 unique International Classification of Disease codes, 10th Revision codes for low back pain to determine a positive case. We compared those with and without back pain across all variables using a chi-square analysis in SAS. Multivariate logistic analysis was performed to adjust for confounding within any single proposed risk factor and the six other proposed risk factors.

RESULTS

Six hundred fifty seven thousand and six thirty soldiers met inclusion criteria; 228,184 of whom had a medical encounter for low back pain (34.7%). All of the proposed risk factors included statistically significant unadjusted and adjusted odds ratios (ORs) with age conferring the greatest risk in soldiers aged 50-59 with an OR of 2.89 (2.73-3.05) compared to those aged 20-29. Obesity-adjusted OR was 1.77 (1.74-1.80) compared to those who were normal weight. Senior Enlisted status-adjusted OR was 1.34 (1.32-1.36). Females were 66% more likely to have low back pain compared to males with an OR of 1.66 (1.63-1.68).

CONCLUSION

Disease burden for low back pain tends to be high in the U.S. Army with 34.7% of service members experiencing low back pain. Older age, obesity, and being an enlisted, female service member are risk factors for these musculoskeletal injuries, which is in agreement with previously reported literature on the topic. To mitigate the burden of low back pain, policies and incentives to encourage healthy body mass index and lifestyle are needed. The results of this work inform future studies aimed at further delineating the risk factors found in this study.

Use of Ultrasound-Guided Platelet-Rich Plasma Injection of the Sacroiliac Joint as a Treatment for Chronic Low Back Pain

Back pain and its associated complications are of increasing importance among military members. The sacroiliac joint (SIJ) is a common source of chronic low back pain (LBP) and functional disability. Many patients suffering from chronic LBP utilize opioids to help control their symptoms. Platelet-rich plasma (PRP) has been used extensively to treat pain emanating from many different musculoskeletal origins; however, its use in the SIJ has been studied only on a limited basis. The patient in this case report presented with chronic LBP localized to the SIJ and subsequent functional disability managed with high-dose opioids. After failure of traditional treatments, she was given an ultrasound-guided PRP injection of the SIJ which drastically decreased her pain and disability and eventually allowed for complete opioid cessation. Her symptom relief continued 1 year after the injection. This case demonstrates the potential of ultrasound-guided PRP injections as a long-term treatment for chronic LBP caused by SIJ dysfunction in military service members, which can also aid in the weaning of chronic opioid use.

Efficacy of automated percutaneous lumbar discectomy for lumbar disc herniation in young male soldiers

Lumbar disc herniation (LDH) often results in back pain and radicular pain and is frequently treated with minimally invasive non-surgical methods in Korean Armed Forces Hospitals. Automated percutaneous lumbar discectomy (APLD) has been reported to have good clinical outcomes with low complication rates; however, the clinical efficacy of APLD performed in young male soldiers is uncertain. In order to clarify the efficacy of APLD for the treatment of LDH in young male soldiers, we designed a retrospective case-control study to compare patients who received APLD with patients treated with epidural steroid injection (ESI) alone.A total of 181 patients were enrolled and divided into the APLD (n = 92) and ESI (n = 89) groups according to the treatment modality. A simple logistic regression analysis was conducted to clarify the difference between the two. To optimize patient selection, APLD group was additionally divided for subgroup analysis into favorable (n = 59) and unfavorable (n = 33) groups based on satisfaction scales. A simple logistic analysis was also performed.The differences between pre- and postoperative numerical rating scale of pain (P = .0027) and hospital-own satisfaction scale (P = .0045) of the APLD group were significantly better compared to those of the ESI group. In terms of subgroup analysis, single-level pathology (P = 0.244) and protruded disc (P = .0443) were associated with favorable outcomes, whereas dual pathology and extruded disc were related with unfavorable outcomes.APLD using Dekompressor, performed in young male soldiers with back and radicular pain owing to LDH, showed better clinical outcomes compared to the ESI only therapy. Additionally, a single-level pathology with protruded disc was associated with favorable outcomes and may be indicated for treatment.

Can We Trust the Literature on Risk Factors and Triggers for Low Back Pain? A Systematic Review of a Sample of Contemporary Literature

Background

Risk factors (RFs) for the "disease" of low back pain (LBP) are probably different from the triggers of new episodes of LBP. Investigating RFs for the onset of the "disease" and the triggers of LBP is problematic if researchers fail to discern the different types of pain-free status of participants at and before baseline. There is a difference between never having had LBP and having been pain-free for a certain period only. In this review, we assessed the dependability of contemporary literature on RFs and triggers of LBP, in relation to the "disease" and the episodes, respectively.

Methods

A literature search from 2010 until 2017 was performed. Information on the definitions of LBP, potential RFs/triggers, and study design was extracted. Studies were reclassified based on the type of LBP concerning the "disease," episode, or mixed/unclear/chronic. RFs and triggers were grouped into major domains, and positive associations listed, respectively, for the "disease" and episodes.

Results

In 42 of the included 47 articles, it was not clear if the authors investigated RFs for the "disease" of LBP or triggers of new episodes. Only one study properly reported RFs for the onset of the "disease" of LBP, and four studies were deemed suitable to investigate triggers for a new episode of LBP. No study reproduced the results of other included studies.

Conclusion

Trustworthy information regarding RFs and triggers of LBP is rare in the current literature. Future research needs to use precise definitions of LBP (onset of the "disease" vs. episodes) and nominate the timing of the associated factors in relation to the types of LBP as these are two critical factors when studying causes of LBP.

Musculoskeletal Pain and Headache in the Active Duty Military Population: An Integrative Review

BACKGROUND

Since 2001, the U.S. Armed Forces' training and deployment have greatly increased, escalating the risk of injury and pain-related issues both at home station and deployment environments.

AIMS

This integrative review examines the incidence, prevalence, and risk factors for musculoskeletal pain (MSP) and headaches in active duty (AD) military populations.

METHODS

Peer-reviewed research published between 2001 and 2016 was identified relevant to MSP and headache in AD military personnel using MeSH terms in key biomedical databases. Inclusion criteria were: epidemiological studies examining MSP or headache as primary or secondary outcome; samples that included AD populations; and studies conducted in the theater of operations, at home station, and in military treatment or Veterans Health Administration facilities.

RESULTS

Twenty-six articles met inclusion criteria. Low back pain (LBP) was the most prevalent MSP diagnosis. The incidence of LBP was 40.5 per 1,000 person-years and was comparable to nonmilitary populations. Inflammation and pain from overuse comprised the largest proportion of injury mechanism, accounting for about 82% of all injuries among nondeployed military personnel. The risk of MSP was greater for AD, female, Army, enlisted personnel, and those with greater time in a motor vehicle. Evidence suggests posttraumatic headache, occurring in up to 92% of military personnel who have sustained a mild traumatic brain injury, is associated with chronic daily headaches.

IMPLICATIONS

Nurses must recognize the consequences military service can have on the development of pain. Nurses have an opportunity to positively impact the health and well-being of military and veteran populations through early recognition and treatment of pain.

LINKING EVIDENCE TO ACTION

The findings from this review underscore considerable magnitude of MSP in military personnel and expose modifiable risk factors and potential targets for designing nurse-led interventions to improve pain and symptoms in military subpopulations.

The relationship between low back pain and professional driving in young military recruits

Background

Episodes of low back pain (LBP) are very common among workers. A number of occupational risk factors have been shown to increase the risk for LBP. One of these risk factors is exposure to whole body vibration, which is a known characteristic in driving professions. The aim of this study was to assess the impact of driving on LBP amongst young professional drivers.

Methods

This is an historical-prospective cohort study based on the Israel Defense Forces (IDF) database of male soldiers drafted between the years 1997–2006. Subjects’ medical history with specific reference to LBP medical history, clinical and radiographic findings were taken as part of the recruitment process to the IDF. The study group included subjects (n = 80,599) from three occupational groups: administrative units (AU), car drivers (CD) and truck drivers (TD) that were followed for 3 years. The incidence and recrudescence rates of LBP were calculated based on standardized LBP severity tiers.

Results

The total incidence rate for LBP was 0.65%, 0.7% and 0.34% for AU, CD and TD respectively. In a comparison between subjects without a history of LBP (category 1) to subjects with a history of LBP without clinical findings (category 2) and subjects with a history of LBP with mild clinical / radiographic findings (category 3), the relative risk (RR) for severe LBP exacerbation was 1.4 (p < 0.001) and 3.8 (p < 0.01), respectively. The LBP exacerbation rates within different severity tiers yielded a similar trend amongst all profession groups.

Conclusions

This study included 80,000 soldiers who represent a population of driving and administrative occupations aged 18–21. The significant risk factors for developing LBP were a previous history of LBP and presence of LBP symptoms at the start of work. A correlation was identified between severity of LBP at the initial examination and further exacerbation of LBP in all examined occupations. Driving as a profession in our (young) age-group was not identified as a risk factor for LBP.

Failure to define low back pain as a disease or an episode renders research on causality unsuitable: results of a systematic review

Background

Causative factors may be different for the very first onset of symptoms of the ‘disease’ of low back pain (LBP) than for ensuing episodes that occur after a pain-free period. This differentiation hinges on a life-time absence of low back pain at first onset and short-term absence for further episodes. In this systematic review, we explored whether researchers make these distinctions when investigating the causality of LBP.

Methods

A literature search of PUBMED, CINAHL, and SCOPUS databases was performed from January 2010 until September 2016 using the search terms ‘low back pain’ or ‘back pain’ and ‘risk factor’ or ‘caus*’ or ‘predict*’ or ‘onset’ or ‘first-time’ or ‘inception’ or ‘incidence’. Two reviewers extracted information on study design, types of episodes of back pain to distinguish the disease of LBP and recurring episodes, and also to determine the definitions of disease- or pain-free periods.

Results

Thirty-three articles purporting to study causes of LBP were included. Upon scrutiny, 31 of the 33 articles were unclear as to what type of causality they were studying, that of the ‘disease’ or the episode, or a mere association with LBP. Only 9 studies used a prospective study design. Five studies appeared to investigate the onset of the disease of LBP, however, only one study truly captured the first incidence of LBP, which was the result of sports injury. Six appeared to study episodes but only one clearly related to the concept of episodes. Therefore, among those 11 studies, nine included both first-time LBP and episodes of LBP. Consequently, 22 studies related to the prevalence of LBP, as they probably included a mixture of first-time, recurring and ongoing episodes without distinction.

Conclusion

Recent literature concerning the causality of LBP does not differentiate between the ‘disease’ of LBP and its recurring episodes mainly due to a lack of a clear definition of absence of LBP at baseline. Therefore, current research is not capable of providing a valid answer on this topic.

Risk Factors for Low Back Pain and Spine Surgery: A Retrospective Cohort Study in Soldiers

INTRODUCTION

Musculoskeletal low back pain (LBP) is commonly treated symptomatically, with practice guidelines advocating reserving surgery for cases that fail conservative care. This study examined medical comorbidities and demographic variables as risk factors for chronic/recurrent LBP, spinal surgery, and time to surgery.

METHODS

A 2015 retrospective cohort study was conducted in U.S. Army soldiers (N=1,092,420) from 2002 to 2011. Soldiers with medical encounters for LBP were identified using ICD-9 codes. Surgical treatment for LBP was identified according to Current Procedural Terminology codes. Comorbid medical conditions (psychological disorders, sleep disorders, tobacco use, alcohol use, obesity) and demographic variables were examined as risk factors for chronic/recurrent LBP within 1 year of the incident encounter, surgery for LBP, and time to surgery.

RESULTS

Of 383,586 patients with incident LBP, 104,169 (27%) were treated for chronic/recurrent LBP and 7,446 (1.9%) had surgery. Comorbid variables showed increased risk of chronic/recurrent LBP ranging from 26% to 52%. Tobacco use increased risk for surgery by 33% (risk ratio, 1.33; 95% CI=1.24, 1.44). Comorbid variables showed 10%-42% shorter time to surgery (psychological disorders, time ratio [TR]=0.90, 95% CI=0.83, 0.98; sleep disorders, TR=0.68, 95% CI=0.60, 0.78; obesity, TR=0.88, 95% CI=0.79, 0.98; tobacco use, TR=0.58, 95% CI=0.54, 0.63; alcohol use, TR=0.85, 95% CI=0.70, 1.05). Women showed 20% increased risk of chronic/recurrent LBP than men but 42% less risk of surgery.

CONCLUSIONS

In the presence of comorbidities associated with mental health, sleep, obesity, tobacco use, and alcohol use, LBP shows increased risk of becoming chronic/recurrent and faster time to surgery.