Much work remains to reach consensus on musculoskeletal injury risk in military service members: A systematic review with meta-analysis

Investigating Research Hotspots of Combat-related Spinal Injuries: A 30-year Bibliometric Analysis Study

INTRODUCTION

Spinal cord injuries often lead to significant motor and sensory deficits, as well as autonomic dysfunction. Compared with normal spinal injuries, combat-related spinal injuries (CRSIs) are usually more complex and challenging to treat because of multiple traumas, firing-line treatments, and arduous initial treatments on a battlefield. Yet numerous issues remain unresolved about clinical treatment and scientific research. The enhancement of CRSI diagnosis and treatment quality by military surgeons and nurses is imperative. The objective of this study is to identify the frontiers, hotspots, and trends among recent research, summarize the development process of clinical trials, and visualize them systematically.

MATERIALS AND METHODS

We collected publications from CRSI based on the Core Collection of Web of Science for 30 years from January 1, 1993 to May 1, 2023.Visualizations of the knowledge maps were produced using VOSviewer and CiteSpace software. We examined annual trends of publications and distribution patterns, the number of publications, as well as the research hotspots.

RESULTS

Among 201 documents, it was found that there was a stable upward trend in publications. There were 2 rapid growth stages during the 30 years. Among all countries, the USA contributed the most publications, along with the highest influence and the most international cooperation. Military Medicine was the journal of the maximum publications, whereas the Spine journal was the most influential one. Keyword co-occurrence analysis and trend topics analysis revealed that these articles focused 5 distinct categories for CRSI.

CONCLUSIONS

As the first bibliometric study focused on CRSI, we demonstrated the evolution of the field and provided future research directions. We summarized the hotspots and 5 clusters published. This would serve as a useful guide for clinicians and scientists regarding CRSI global impacts.

Predictive Validity of Multifactorial Injury Risk Models and Associated Clinical Measures in the U.S. Population

Background: Popular movement-based injury risk screens were shown to lack predictive precision, leading to interest in multifactorial models. Furthermore, there is a lack of research regarding injury risk assessment for those currently or planning to be recreationally active. This study aims to provide injury risk insights by analyzing multifactorial injury risk models and associated clinical measures in the U.S. population. Methods: Data related to injury, inflammatory markers, physical functioning, body composition, physical activity, and other variables from 21,033 respondents were extracted from NHANES. Odds ratios for self-reported injury were calculated for single predictors and risk models. Case-control and principal component analyses (PCA) were conducted to elucidate confounders and identify risk factor clusters, respectively. Receiver operating characteristic analysis was used to test the precision of a risk factor cluster to identify pain points and functional difficulties. Results: Sociodemographic, individual, and lifestyle factors were strongly associated with higher odds of injury. Increases in fibrinogen and C-reactive protein were significantly associated with all risk groups. Membership to the high-risk group (age over 40, obesity, no muscle-strengthening activities, sedentary lifestyle, and low back pain) predicted at least one functional difficulty with 67.4% sensitivity and 87.2% specificity. In the injury group, bone turnover markers were higher, yet confounded by age, and there was a significantly higher prevalence of self-reported osteoporosis compared to the control. In males, low testosterone was associated with injury, and high estradiol was associated with pain and functional difficulties. In females, high follicle-stimulating hormone was associated with functional difficulties. PCA revealed four high-risk profiles, with markers and activities showing distinct loadings. Conclusions: A comprehensive approach to injury risk assessment should consider the nexus of aging, lifestyle, and chronic disease to enhance tailored injury prevention strategies, fostering safe and effective physical activity participation and reducing the burden of musculoskeletal disorders.

Prevalence of Pain With Movement in Active Duty US Army Soldiers

INTRODUCTION

Soldiers must be able to perform a multitude of physically demanding tasks as part of their regular duty, but their physical readiness is often degraded due to pain and musculoskeletal injury (MSKI). The presence of pain with movement has been associated with increased MSKI risk in Soldiers. Improved awareness of the prevalence of painful movements in uninjured Soldiers could help inform Army injury mitigation efforts. The purpose of this study was to identify the prevalence of pain with movement in a population of healthy active duty Soldiers.

MATERIALS AND METHODS

The Selective Functional Movement Assessment-Top Tier Movements (SFMA-TTM), active range of motion (AROM) of the hips and shoulders, and the elicitation of pain with movement were measured in 268 healthy US Army Soldiers. Descriptive statistics were generated for the number of painful movements for each measure and inferential statistics; independent t-test and one-way independent analysis of variance (ANOVA) were used for analysis of the other measures.

RESULTS

Greater than half (59%) of the participants reported pain with at least 1 movement and more than 41% reported pain with 2 or more movements. Soldiers reported a mean of 1.35 painful movements on the SFMA-TTM assessment and a mean of 1.54 painful AROM movements.

CONCLUSIONS

Pain with functional movement patterns was common across a sample of uninjured Soldiers. The presence of pain with movement warrants further evaluation as it may impact a Soldier's physical performance, risk for future injury, and overall quality of life.

High Physical Exposure During Female Recruits' Basic Military Training in Sweden-A Descriptive Study

INTRODUCTION

There is a knowledge gap concerning the occurrence of physical complaints/injuries, i.e., musculoskeletal disorders (MSD), among Swedish women who undergo basic military training (BMT). The aims were to describe prevalence and factors related to MSD and explore physical exposure and performance in Swedish female recruits during BMT.

MATERIALS AND METHODS

A total of 144 females (mean age 22 years) who underwent BMT in 2016 participated in this cross-sectional study. Data regarding self-reported MSD, physical performance, physical activity and exercise, motivation and mental and physical preparation, and physical exposure during BMT and perceived health were collected at the end of BMT through the Musculoskeletal Screening Protocol questionnaire. Additional data on muscle strength were retrieved from IsoKai isokinetic lift tests. Descriptive and analytic (paired samples t-test and logistic binary regression) statistics were used.

RESULTS

The prevalence of MSD was high, with 33% (n = 48) reporting MSD before BMT, 78% (n = 113) during, and 50% (n = 72) at the end of BMT. Knee and upper back were the most frequently reported MSD locations. Forty-four (30%) participants felt insufficiently physically prepared for BMT. The physical exposure was high with loaded marches/runs and carrying heavy loads as the most demanding tasks. The longest walking distance was reportedly 55 km, and the reported maximum load was 50 kg. Forty-five participants (31%) had carried a load representing over 50% of their body weight. Most participants reported good to excellent health at the end of BMT. There was a small (8 N) but significant (P = 0.045) increase in mean force over time. Two variables, MSD before BMT (odds ratio 2.24, P = 0.03) and being physically unprepared (odds ratio 3.03, P < 0.01), were associated with MSD at the end of BMT.

CONCLUSION

This study showed that the prevalence of MSD in Swedish female recruits was high before, during, and at the end of BMT, with knee and upper back as the most frequent locations. Although the physical exposure during BMT was occasionally high, self-rated health was mainly perceived as good to excellent at the end of BMT. Previous MSD and being physically unprepared were related to MSD at the end of BMT. These important and relevant findings indicate the necessity for implementing interventions to increase physical fitness and treat MSD at the beginning of BMT.

Incidence and Risk Factors for Bone Stress Injuries in United States Air Force Special Warfare Trainees

OBJECTIVES

To determine (1) the incidence rate of lower extremity (LE) bone stress injuries (BSIs) in United States Air Force Special Warfare (AFSPECWAR) trainees during the first 120 days of training, and (2) factors associated with sustaining a LE BSI.

DESIGN

Retrospective cohort study.

METHODS

AFSPECWAR Airmen (n = 2,290, mean age = 23.7 ± 3.6 years) entering an intensive 8-week preparatory course "SW-Prep" between October 2017 and May 2021. We compared anthropometric measurements, previous musculoskeletal injury (MSKI), fitness measures, and prior high-impact sports participation in those that did and did not suffer a BSI during the 120-day observation period using independent t-tests and chi-square tests. A multivariable binary logistic regression was used to determine factors associated with suffering a BSI.

RESULTS

A total of 124 AFSPECWAR trainees suffered a BSI during the surveillance period, yielding an incidence proportion of 5.41% and an incidence rate of 1.4 BSIs per 100 person-months. The multivariate logistic regression revealed that lower 2-minute sit-up scores, no prior history of participation in a high-impact high-school sport, and a history of prior LE MSKI were associated with suffering a BSI. A receiver operator characteristic curve analysis yielded an area under the curve (AUC) of 0.727.

CONCLUSION

BSI incidence proportion for our sample was similar to those seen in other military settings. Military trainees without a history of high-impact sports participation who achieve lower scores on sit-ups tests and have a history of LE MSKI have a higher risk for developing a LE BSI during the first 120 days of AFSPECWAR training.

Identifying special operative trainees at-risk for musculoskeletal injury using full body kinematics

Introduction: Non-combat musculoskeletal injuries (MSKIs) during military training significantly impede the US military's functionality, with an annual cost exceeding $3.7 billion. This study aimed to investigate the effectiveness of a markerless motion capture system and full-body biomechanical movement pattern assessments to predict MSKI risk among military trainees. Methods: A total of 156 male United States Air Force (USAF) airmen were screened using a validated markerless biomechanics system. Trainees performed multiple functional movements, and the resultant data underwent Principal Component Analysis and Uniform Manifold And Projection to reduce the dimensionality of the time-dependent data. Two approaches, semi-supervised and supervised, were then used to identify at-risk trainees. Results: The semi-supervised analysis highlighted two major clusters with trainees in the high-risk cluster having a nearly five times greater risk of MSKI compared to those in the low-risk cluster. In the supervised approach, an AUC of 0.74 was produced when predicting MSKI in a leave-one-out analysis. Discussion: The application of markerless motion capture systems to measure an individual's kinematic profile shows potential in identifying MSKI risk. This approach offers a novel way to proactively address one of the largest non-combat burdens on the US military. Further refinement and wider-scale implementation of these techniques could bring about substantial reductions in MSKI occurrence and the associated economic costs.

Predicting Subsequent Injury after Being Cleared to Return to Work from Initial Lumbar or Lower Extremity Injury

PURPOSE

The purpose of this study is to develop a model to predict re-injury after being cleared to return to full duty from an initial injury.

METHODS

This was a prediction model derivation cohort study. Military service members cleared for unrestricted full duty after sustaining a musculoskeletal injury were enrolled from three large military hospitals. Medical history, demographics, psychological profile, physical performance (Y-Balance Test™, Functional Movement Screen™, Selective Functional Movement Assessment, triple hop, closed chain ankle dorsiflexion, 2-mile run, 75% bodyweight carry time), and past injury history were assessed. Monthly text messages, medical records and limited duty databases were used to identify injuries resulting in time lost from work in the following year.

RESULTS

Four hundred fifty participants (65 females), ages 18 to 45 yr were analyzed. Fifteen variables were included in the final model. The area under the curve was 0.74 (95% confidence interval, 0.69-0.80), indicating good performance. The calibration score of the model was 1.05 (95% confidence interval, 0.80-1.30) indicating very good performance. With an injury incidence in our cohort of 38.0%, the treat all net benefit was 0.000, and the net benefit of our predictive model was 0.251. This means 25 additional soldiers out of every 100 were correctly identified as high risk for injury compared with not using a prediction model at all.

CONCLUSIONS

This multivariable model accurately predicted injury risk after returning for full duty and was better than not using a prediction model at all (an additional 25 of every 100 tactical athletes were correctly identified). This model provides guidance for proper decision making about when these individuals are not ready to return to full duty, with higher risk of a subsequent injury.

Barriers and facilitators to implementation of musculoskeletal injury mitigation programmes for military service members around the world: a scoping review

INTRODUCTION

Musculoskeletal injury (MSK-I) mitigation and prevention programmes (MSK-IMPPs) have been developed and implemented across militaries worldwide. Although programme efficacy is often reported, development and implementation details are often overlooked, limiting their scalability, sustainability and effectiveness. This scoping review aimed to identify the following in military populations: (1) barriers and facilitators to implementing and scaling MSK-IMPPs; (2) gaps in MSK-IMPP research and (3) future research priorities.

METHODS

A scoping review assessed literature from inception to April 2022 that included studies on MSK-IMPP implementation and/or effectiveness in military populations. Barriers and facilitators to implementing these programmes were identified.

RESULTS

From 132 articles, most were primary research studies (90; 68.2%); the remainder were review papers (42; 31.8%). Among primary studies, 3 (3.3%) investigated only women, 62 (69%) only men and 25 (27.8%) both. Barriers included limited resources, lack of stakeholder engagement, competing military priorities and equipment-related factors. Facilitators included strong stakeholder engagement, targeted programme design, involvement/proximity of MSK-I experts, providing MSK-I mitigation education, low burden on resources and emphasising end-user acceptability. Research gaps included variability in reported MSK-I outcomes and no consensus on relevant surveillance metrics and definitions.

CONCLUSION

Despite a robust body of literature, there is a dearth of information about programme implementation; specifically, barriers or facilitators to success. Additionally, variability in outcomes and lack of consensus on MSK-I definitions may affect the development, implementation evaluation and comparison of MSK-IMPPs. There is a need for international consensus on definitions and optimal data reporting elements when conducting injury risk mitigation research in the military.

Musculoskeletal Complaint Epidemiology in Australian Special Operation Forces Trainees

INTRODUCTION

Elite military trainees are burdened by high numbers of musculoskeletal (MSK) injuries and are a priority military population for injury prevention. This research aims to describe the MSK complaint epidemiology of trainees undertaking special forces (SF) training in the Australian Defence Force (ADF). One barrier to accurate injury surveillance in military populations is that traditional surveillance methods rely on personnel engaging with the military healthcare system to collect injury data. This approach is likely to underestimate the injury burden as it is known that many military personnel, particularly trainees, avoid reporting their injuries because of various motives. Subsequently, the insights from surveillance systems may underestimate the injury burden and limit the ability to inform prevention requirements. This research aims to actively seek MSK complaint information directly from trainees in a sensitive manner to mediate injury-reporting behaviors.

MATERIALS AND METHODS

This descriptive epidemiology study included two consecutive cohorts of ADF SF trainees from 2019 to 2021. Musculoskeletal data items and their respective recording methods were based on international sports injury surveillance guidelines and adapted to a military context. Our case definition encompassed all injuries or physical discomforts as recordable cases. A unit-embedded physiotherapist retrospectively collected MSK complaint data from selection courses and collected prospective data over the training continuum. Data collection processes were external to the military health care system to mediate reporting avoidance and encourage injury reporting. Injury proportions, complaint incidence rates, and incidence rate ratios were calculated and compared between training courses and cohorts.

RESULTS

In total, 334 MSK complaints were reported by 103 trainees (90.4%), with a complaint incidence rate of 58.9 per 1,000 training weeks (95% CI, 53.0-65.5). Of these MSK complaints, 6.4% (n = 22) resulted in time loss from work. The lumbar spine (20.6%, n = 71) and the knee (18.9%, n = 65) were the most frequently affected body parts. Most of the MSK complaints were reported during selection courses (41.9%), followed by field survival and team tactics (23.0%) and urban operations courses (21.9%). Physical training accounted for 16.5% of complaints. Fast-roping training was associated with more severe MSK complaints.

CONCLUSIONS

Musculoskeletal complaints are highly prevalent in ADF SF trainees. Complaints are more frequently reported in selection and qualification training courses than in physical training. These activities are priorities for focused research to understand injury circumstances in ADF elite training programs to inform injury prevention strategies. A strength of our study is the data collection methods which have provided greater MSK complaint information than past research; however, much work remains in conducting consistent and accurate surveillance. Another strength is the use of an embedded physiotherapist to overcome injury-reporting avoidance. Embedded health professionals are recommended as continued practice for ongoing surveillance and early intervention.

Epidemiology of musculoskeletal injury in military recruits: a systematic review and meta-analysis

BACKGROUND

Injuries are a common occurrence in military recruit training, however due to differences in the capture of training exposure, injury incidence rates are rarely reported. Our aim was to determine the musculoskeletal injury epidemiology of military recruits, including a standardised injury incidence rate.

METHODS

Epidemiological systematic review following the PRISMA 2020 guidelines. Five online databases were searched from database inception to 5th May 2021. Prospective and retrospective studies that reported data on musculoskeletal injuries sustained by military recruits after the year 2000 were included. We reported on the frequency, prevalence and injury incidence rate. Incidence rate per 1000 training days (Exact 95% CI) was calculated using meta-analysis to allow comparisons between studies. Observed heterogeneity (e.g., training duration) precluded pooling of results across countries. The Joanna Briggs Institute Quality Assessment Checklist for Prevalence Studies assessed study quality.

RESULTS

This review identified 41 studies comprising 451,782 recruits. Most studies (n = 26; 63%) reported the number of injured recruits, and the majority of studies (n = 27; 66%) reported the number of injuries to recruits. The prevalence of recruits with medical attention injuries or time-loss injuries was 22.8% and 31.4%, respectively. Meta-analysis revealed the injury incidence rate for recruits with a medical attention injury may be as high as 19.52 injuries per 1000 training days; and time-loss injury may be as high as 3.97 injuries per 1000 training days. Longer recruit training programs were associated with a reduced injury incidence rate (p = 0.003). The overall certainty of the evidence was low per a modified GRADE approach.

CONCLUSION

This systematic review with meta-analysis highlights a high musculoskeletal injury prevalence and injury incidence rate within military recruits undergoing basic training with minimal improvement observed over the past 20 years. Longer training program, which may decrease the degree of overload experienced by recruit, may reduce injury incidence rates. Unfortunately, reporting standards and reporting consistency remain a barrier to generalisability.

TRIAL REGISTRATION

PROSPERO (Registration number: CRD42021251080).

Predicting Postoperative Injury and Military Discharge Status After Knee Surgery in the US Army

BACKGROUND

Researchers have assessed postoperative injury or disability predictors in the military setting but typically focused on 1 type of surgical procedure at a time, used relatively small sample sizes, or investigated mixed cohorts with civilian populations.

PURPOSE

To identify the relationship between baseline variables and injury incidence or military discharge status in US Army soldiers after knee surgery.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were obtained from a repository containing personnel, performance, and medical records for all active-duty US Army soldiers. Multivariate logistic regressions were used to estimate the effects of numerous variables on postoperative injury or on medical discharge. Variable selection and model validation were conducted using the k-fold method.

RESULTS

A total of 7567 soldiers underwent knee surgery between 2017 and 2019. Meniscal procedures were the most common type of surgery (39%), and approximately 71% of the cohort had a postoperative injury. Significant predictors for sustaining a postoperative injury included having a previous nonknee injury (odds ratio [OR], 1.5), female sex (OR, 1.3), and Black race (OR, 1.2). Within 4 years after surgery, 17% of soldiers were discharged from the military because of knee-related disability. Significant predictors for discharge from duty included enlisted rank (OR, 2.3), recent fitness test failure (OR, 1.9), number of previous knee surgeries (OR, 1.7), and having a previous nonknee injury (OR, 1.6).

CONCLUSION

After knee surgery, nearly three-fourths of the soldiers in this cohort sustained a postoperative injury and almost one-fifth of soldiers were medically discharged from the military within 4 years. This study identified variables that indicate statistically increased risk for these postoperative outcomes and highlighted potentially modifiable factors.

Factors Associated With Neuromusculoskeletal Injury and Disability in Navy and Marine Corps Personnel

INTRODUCTION

Neuromusculoskeletal injuries (NMSKI) are very common in the military, which contribute to short- and long-term disability.

MATERIALS AND METHODS

Population-level NMSKI, limited duty (LIMDU), and long-term disability episode counts in the U.S. Navy (USN) and U.S. Marine Corps (USMC) from December 2016 to August 2021 were extracted from the Musculoskeletal Naval Epidemiological Surveillance Tool. The incidence of NMSKI, LIMDU, and long-term disability was calculated. A hurdle negative binomial regression evaluated the association of body region, sex, age, rank, age by rank, and service branch on NMSKI, LIMDU, and long-term disability incidence.

RESULTS

From December 2016 to August 2021, there were 2,004,196 NMSKI episodes (USN: 3,285/1,000 Sailors; USMC: 4,418/1,000 Marines), 16,791 LIMDU episodes (USN: 32/1,000 Sailors; USMC: 29/1,000 Marines), and 2,783 long-term disability episodes (USN: 5/1,000 Sailors; USMC: 5/1,000 Marines). There was a large-magnitude protective effect on NMSKI during the pandemic (relative risk, USN: 0.70; USMC: 0.75). Low back and ankle-foot were the most common, primarily affecting female personnel, aged 25-44 years, senior enlisted, in the USMC. Shoulder, arm, pelvis-hip, and knee conditions had the greatest rates of disability, with female sex, enlisted ranks, aged 18-24 years, and service in the USMC having the most salient risk factors.

CONCLUSION

Body region, sex, age, rank, and branch were the salient factors for NMSKI. The significant protective effect during the pandemic was likely a function of reduced physical exposure and limited access to nonurgent care. Geographically accessible specialized care, aligned with communities with the greatest risk, is needed for timely NMSKI prevention, assessment, and treatment.

Musculoskeletal Injury Risk Stratification: A Traffic Light System for Military Service Members

Risk factor identification is a critical first step in informing musculoskeletal injury (MSKI) risk mitigation strategies. This investigation aimed to determine if a self-reported MSKI risk assessment can accurately identify military service members at greater MSKI risk and determine whether a traffic light model can differentiate service members' MSKI risks. A retrospective cohort study was conducted using existing self-reported MSKI risk assessment data and MSKI data from the Military Health System. A total of 2520 military service members (2219 males: age 23.49 ± 5.17 y, BMI 25.11 ± 2.94 kg/m²; and 301 females: age 24.23 ± 5.85 y, BMI 25.59 ± 3.20 kg/m², respectively) completed the MSKI risk assessment during in-processing. The risk assessment consisted of 16 self-report items regarding demographics, general health, physical fitness, and pain experienced during movement screens. These 16 data points were converted to 11 variables of interest. For each variable, service members were dichotomized as at risk or not at risk. Nine of the 11 variables were associated with a greater MSKI risk and were thus considered as risk factors for the traffic light model. Each traffic light model included three color codes (i.e., green, amber, and red) to designate risk (i.e., low, moderate, and high). Four traffic light models were generated to examine the risk and overall precision of different cut-off values for the amber and red categories. In all four models, service members categorized as amber [hazard ratio (HR) = 1.38-1.70] or red (HR = 2.67-5.82) were at a greater MSKI risk. The traffic light model may help prioritize service members who require individualized orthopedic care and MSKI risk mitigation plans.

Musculoskeletal injuries in US Air Force Tactical Air Control Party trainees: an 11-year longitudinal retrospective cohort study and presentation of a musculoskeletal injury classification matrix

INTRODUCTION

Little is known of the epidemiology of musculoskeletal injuries (MSKIs) in US Air Force Special Warfare (AFSPECWAR) Tactical Air Control Party trainees. The purpose of this longitudinal retrospective cohort study was to (1) report the incidence and type of MSKI sustained by AFSPECWAR trainees during and up to 1 year following training, (2) identify factors associated with MSKI, and (3) develop and present the MSKI classification matrix used to identify and categorise injuries in this study.

METHODS

Trainees in the Tactical Air Control Party Apprentice Course between fiscal years 2010-2020 were included. Diagnosis codes were classified as MSKI or non-MSKI using a classification matrix. Incidence rates and incidence proportion for injury types and regions were calculated. Measures were compared for differences between those who did and did not sustain an MSKI during training. A Cox proportional hazards model was used to identify factors associated with MSKI.

RESULTS

Of the 3242 trainees, 1588 (49%) sustained an MSKI during training and the cohort sustained MSKIs at a rate of 16 MSKI per 100 person-months. Overuse/non-specific lower extremity injuries predominated. Differences were seen in some baseline measures between those who did and did not sustain an MSKI. Factors retained in the final Cox regression model were age, 1.5-mile run times and prior MSKI.

CONCLUSION

Slower run times and higher age were associated with an increased likelihood of MSKI. Prior MSKI was the strongest predictor of MSKI during training. Trainees sustained MSKIs at a higher rate than graduates in their first year in the career field. The MSKI matrix was effective in identifying and categorising MSKI over a prolonged (12-year) surveillance period and could be useful for future injury surveillance efforts in the military or civilian settings. Findings from this study could inform future injury mitigation efforts in military training environments.

Injury Profiles of Police Recruits Undergoing Basic Physical Training: A Prospective Cohort Study

Purpose A lack of published epidemiological data among police recruits presents a major challenge when designing appropriate prevention programs to reduce injury burden. We aimed to report the injury epidemiology of Western Australian (WA) Police Force recruits and examine sex and age as injury risk factors. Methods Retrospective analyses were conducted of prospectively collected injury data from WA Police Force recruits between 2018-2021. Injury was defined as 'time-loss' and injury incidence rate per 1000 training days (Poisson exact 95% confidence intervals) was calculated. For each region and type of injury, the incidence, severity, and burden were calculated. The association between age, sex, and injury occurrence were assessed using Cox regression time-to-event analysis. Results A total of 1316 WA Police Force recruits were included, of whom 264 recruits sustained 304 injuries. Injury prevalence was 20.1% and the incidence rate was 2.00 (95%CI 1.78-2.24) injuries per 1000 training days. Lower limb injuries accounted for most of the injury burden. Ligament/ joint injuries had the highest injury tissue/pathology burden. The most common activity injuring recruits was physical training (31.8% of all injuries). Older age (Hazard Ratio = 1.5, 95%CI = 1.2 to 1.9, p = 0.002) and female sex (Hazard Ratio = 1.4, 95%CI = 1.3 to 1.6, p < 0.001) increased risk of injury. Conclusion Prevention programs targeting muscle/tendon and ligament/joint injuries to the lower limb and shoulder should be prioritised to reduce the WA Police Force injury burden. Injury prevention programs should also prioritise recruits who are over 30 years of age or of female sex, given they are a higher risk population.

The relationship between sleep, pain,and musculoskeletal injuries in US Army Soldiers

INTRODUCTION

The purpose of this study was to investigate the relationship between sleep and pain in military personnel and to determine if metrics of sleep and pain intensity differ between the injured and uninjured in this population.

METHODS

Active-duty US Army Soldiers (n=308; 26.8±6.5 years, 82% male) from the 2nd Infantry Division, Joint Base Lewis-McChord, Washington, and 101st Airborne Division, Fort Campbell, Kentucky, completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and questionnaires about current musculoskeletal injuries and pain intensity (0=no pain to 10=worst imaginable pain). Pearson correlation coefficients were used to assess the association between pain and sleep. Differences in sleep and pain between injured and uninjured participants were determined using an analysis of covariance.

RESULTS

Pain intensity was positively correlated with sleep quality (global PSQI score, r=0.337, p<0.001) and daytime sleepiness (ESS score, r=0.163, p=0.005), and negatively associated with sleep duration (r=-0.118, p=0.039). Injured participants accounted for 37.7% (n=116) of the study population. Injured participants reported greater pain intensity (3.7±2.5 vs 1.3±1.9, p<0.001), were older (28.5±7.4 years vs 25.8±5.7 years, p=0.001) and in the service longer (6.3±6.3 years vs 4.6±4.7 years, p=0.013) than uninjured participants. Injured participants had higher global PSQI scores (9.0±4.1 vs 6.4±3.4, p<0.001), including each of the seven PSQI components (all p<0.050), and reported sleeping less per night than uninjured participants (5.7±1.3 hours vs 6.1±1.2 hours, p=0.026).

CONCLUSION

These data demonstrate that pain intensity is associated with sleep in active-duty US Army Soldiers and that those who report a musculoskeletal injury, regardless of age and time in service, report poorer sleep quality, shorter sleep durations, and greater levels of pain than uninjured Soldiers.

The Influence of Therapeutic Exercise after Ankle Sprain on the Incidence of Subsequent Knee, Hip, and Lumbar Spine Injury

PURPOSE

This study aimed to investigate the burden of knee, hip, and lumbar spine disorders occurring in the year after an ankle sprain and the influence therapeutic exercise (TE) has on this burden.

METHODS

A total of 33,361 individuals diagnosed with ankle sprain in the Military Health System between 2010 and 2011 were followed for 1 yr. The prevalence of knee, hip, and lumbar care-seeking injuries sustained after sprain was identified. Relationships between demographic groups, ankle sprain type, and use of TE with rate of proximal injuries were evaluated using Cox proportional hazard models to determine hazard rate effect modification by attribute. The observed effect of TE for ankle sprain on rate of injury to proximal joints was evaluated using Kaplan-Meier survival analyses.

RESULTS

Of the total cohort, 20.5% ( n = 6848) of patients sustained a proximal injury. Specifically, 10.1% of the cohort sustained a knee ( n = 3356), 2.9% a hip ( n = 973), and 10.3% a lumbar injury ( n = 3452). Less than half of the cohort received TE after initial sprain. Patients that did were less likely to have subsequent knee (HR = 0.87, 95% confidence interval [CI] = 0.80-0.94), hip (HR = 0.68, 95% CI = 0.58-0.79), or lumbar (HR = 0.82, 95% CI = 0.76-0.89) injuries.

CONCLUSIONS

One in five individuals that sought care for an ankle sprain experienced a proximal joint injury in the following year. TE for the management of the initial ankle sprain reduced the likelihood of proximal injury diagnosis and should be considered in treatment plans for return to work and sport protocols after ankle sprains.

Does policy that provides choice in athletic footwear affect musculoskeletal injury risk in US Coast Guard recruits?

INTRODUCTION

Musculoskeletal injuries (MSKIs) are ubiquitous during initial entry military training, with overuse injuries the most common. A common injury mechanism is running, an activity that is integral to US Coast Guard (USCG) training and a requirement for graduation. The purpose of this study was to assess the effects of a policy that allowed for athletic footwear choice on risk of lower quarter MSKI in USCG recruits.

METHODS

A retrospective cohort study was performed that included 1230 recruits (1040 men, 190 women) who trained under a policy that allowed self-selection of athletic footwear and 2951 recruits (2329 men, 622 women) who trained under a policy that mandated use of prescribed uniform athletic shoes and served as controls. Demographic data and physical performance were derived from administrative records. Injury data were abstracted from a medical tracking database. Unadjusted risk calculations and multivariable logistic regression assessing the effects of group, age, sex, height, body mass and 2.4 km run times on MSKI were performed.

RESULTS

Ankle-foot, leg, knee and lumbopelvic-hip complex injuries were ubiquitous in both groups (experimental: 13.13 per 1000 person-weeks; control: 11.69 per 1000 person-weeks). Group was not a significant factor for any of the injuries assessed in either the unadjusted or adjusted analysis, despite widespread reports of pain (58.6%), perceived injury attribution (15.7%), perceived deleterious effect on performance (25.3%), general dissatisfaction (46.3%) and intended discontinuance of use following graduation (87.7%).

CONCLUSION

MSKI continues to be a major source of morbidity in the recruit training population. The policy that allowed USCG recruits to self-select athletic footwear did not decrease or increase the risk of MSKI. While regulations pertaining to footwear choice did not influence injury outcomes, there was general dissatisfaction with the prescribed uniform athletic footwear conveyed by the recruits and widespread reports of discomfort, perceived deleterious effects from wear and intended discontinued use following training completion.

The Association Between Sleep and Musculoskeletal Injuries in Military Personnel: A Systematic Review

INTRODUCTION

Musculoskeletal injuries (MSKIs) are a significant health problem in the military. Accordingly, identifying risk factors associated with MSKI to develop targeted strategies that attenuate injury risk remains a top priority within the military. Insufficient sleep has garnered increased attention as a potential risk factor for MSKI in both civilians and military personnel. Yet, there are no systematic evaluations of the potential association between sleep and MSKI in the military. The purpose of this review is to examine the relationship between sleep and injury in military personnel.

MATERIALS AND METHODS

Literature searches were performed in multiple electronic databases using keywords relevant to sleep quantity and quality, MSKI, and military populations. Two investigators independently assessed the methodological quality of each study using the Newcastle-Ottawa Scale for cohort studies or an adapted form of this scale for cross-sectional studies.

RESULTS

The search yielded 2402 total citations, with 8 studies (3 cohort and 5 cross-sectional) fitting the inclusion criteria. Overall, the systematic review found 5 of the 8 reviewed studies supporting an association between sleep (quality and duration) and MSKI in military personnel. Specifically, poor sleep was associated with increased injury incidence in 2 cohort and 3 cross-sectional studies.

CONCLUSION

This is the first systematic review to evaluate the published literature on the association between sleep and MSKI risk in military populations. Although there is currently limited research on this topic, findings suggest that sleep is associated with MSKI and should be considered when designing strategies aimed at reducing MSKI risk in military personnel.

The Use of Force Plate Vertical Jump Scans to Identify Special Warfare Trainees at Risk for Musculoskeletal Injury: A Large Cohort Study

BACKGROUND

Vertical jump scans from commercially available force plate systems are increasingly used in military settings to screen for musculoskeletal injury (MSKI) risk. However, to date, no studies have determined the ability of these tools to identify tactical athletes at elevated risk for MSKI.

PURPOSE

To (1) determine associations between scores from a force plate vertical jump test and the likelihood of experiencing an MSKI and to (2) establish the test-retest reliability of the output scores from the force plate system used.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 823 male Air Force Special Warfare trainees underwent force plate vertical jump screenings before entering an 8-week training course at US Air Force Special Warfare Training Wing. MSKI data were collected for the 8-week surveillance period for each trainee. Logistic regression analyses were used to identify associations between baseline force plate jump scores and the likelihood of MSKI (any region) or a lower extremity MSKI (significance level, P = .05). The test-retest portion of the study collected force plate output scores from 12 trainees performing 3 trials of the standard test procedures. The reliability of 5 output scores was assessed with intraclass correlation coefficients (ICCs) using a single rater.

RESULTS

All force plate output scores demonstrated excellent test-retest reliability (ICC >0.90). Overall 308 (36.4%) trainees had an MSKI during the surveillance period. However, no significant associations were found between the proprietary force plate vertical jump scan output scores and the likelihood of experiencing either an MSKI or a lower extremity MSKI.

CONCLUSION

Output scores from this commercially available force plate system did not identify Air Force Special Warfare trainees at elevated risk of experiencing an MSKI.

Test-Retest Reliability and Translation of the Musculoskeletal Screening Protocol Questionnaire Used in the Swedish Armed Forces

INTRODUCTION

Musculoskeletal disorders (MSDs) in military personnel are common, and it is important to identify those at risk so that appropriate preventive and rehabilitative strategies can be undertaken. The Musculoskeletal Screening Protocol (MSP) questionnaire is part of the implemented prevention strategy to reduce MSDs in the Swedish Armed Forces. The aims of this study were to evaluate the questionnaire's reliability and to translate it into English.

MATERIALS AND METHODS

One-week test-retest reliability of the questionnaire was evaluated in a sample of 35 Swedish military personnel. Reliability was evaluated by calculations of Cohen's kappa or quadratic-weighted kappa. Percent agreement was used as a parameter for measurement error. Translation into English included forward and backward translations and expert committee discussions.

RESULTS

Kappa values relating to physical complaints/injuries were excellent (>0.75) except for knee and lower leg MSDs and for the intensity ratings, where Kappa values were mostly interpreted as fair-to-good (0.4-0.75). Kappa values of items pertaining physical performance, physical activity and exercise, eating and tobacco habits, sleep, and perceived health ranged between 0.72 and 1. Kappa values for feeling mentally or physical prepared were 0.47 and 0.65, respectively. Most percentage agreement values ranged between 90% and 100%. The English version was found to be satisfactorily equivalent to the Swedish MSP questionnaire.

CONCLUSION

The Swedish MSP questionnaire was found to be highly reliable and was satisfactorily translated into English. This provides support for the questionnaire's ability to trustworthily capture the prevalence of MSDs and perceived health in military personnel. Future research is warranted on the psychometric properties of the English MSP questionnaire.

Comparison of Musculoskeletal Injury and Behavioral Health Diagnoses Among U.S. Army Active Duty Servicewomen in Ground Combat and Non-Ground Combat Military Occupational Specialties

INTRODUCTION

The U.S. Army's Soldier 2020 program, which started in January 2016, was designed to achieve full integration of women in all military occupational specialties. This study was undertaken to determine differences in risk of musculoskeletal injury and behavioral health (BH) disorders among U.S. Army Active Duty Servicewomen (ADSW) in ground combat military occupational specialties (MOS) versus those in non-ground combat MOS since the start of the program until January 2019.

MATERIALS AND METHODS

Using healthcare claims data from the Military Health System's Data Repository we conducted a cross-sectional study on ADSW from January 1, 2016 to January 1, 2019 and categorized them as either ground combat specialists (GCSs) or non-ground combat specialists (NGCSs). We identified all female soldiers in our cohort with a musculoskeletal injury (MSKI) and/or BH diagnosis during the study period. A multivariable logistic regression, adjusted by pregnancy or delivery status, was used to assess risk factors associated with GCS and included soldier age, race, body mass index (BMI), tobacco use, alcohol/substance use, and MSKI and BH status as predictor variables.

RESULTS

A total of 92,443 U.S. Army ADSW were identified, of whom 3,234 (3.5%) were GCS (infantry, field artillery, cavalry/armor, and air defense) and 89,209 (96.5%) were in non-ground combat billets. A large difference was observed when comparing the age of the population by occupation; GCS women were predominantly between the ages of 18-23 years (71.9%), compared to NGCS women aged 18-23 (41.0%). Top MSKI and BH diagnoses for both occupations were joint pain (44.9% GCS, 50.2% NGCS) and adjustment disorders (26.2% GCS, 28.0% NGCS). GCS women had lower odds for musculoskeletal injury (0.86 AOR, 0.79-0.93 CI, P = 0.0002), obesity per BMI classification (0.82 AOR, 0.70-0.97 CI, P = 0.0214), and BH disorders (0.87 AOR, 0.80-0.95 CI, P = 0.0019); and higher odds for tobacco use (1.44 AOR, 1.27-1.63 CI, P < 0.0001), substance use (1.36 AOR, 1.04-1.79 CI, P = 0.0257), and alcohol use (1.18 AOR, 1.02-1.38 CI, P = 0.0308) when compared to NGCS women.

CONCLUSIONS

With the increasing focus on soldier medical readiness in today's U.S. Army, the health of all soldiers is of paramount concern to command groups, unit leaders, and individual soldiers. The integration of women into ground combat military occupational specialties is a relatively new program; further longitudinal research of these groups should follow, focusing on their progression and improvement in soldier readiness, overall health, and the well-being of all servicewomen.

Improving musculoskeletal injury surveillance methods in Special Operation Forces: A Delphi consensus study

Musculoskeletal injury mitigation is a priority in military organisations to protect personnel health and sustain a capable workforce. Despite efforts to prevent injury, inconsistencies exist in the evidence used to support these activities. There are many known limitations in the injury surveillance data reported in previous Special Operation Forces (SOF) research. Such studies often lack accurate, reliable, and complete data to inform and evaluate injury prevention activities. This research aimed to achieve expert consensus on injury surveillance methods in SOF to enhance the quality of data that could be used to inform injury prevention in this population. A Delphi study was conducted with various military injury surveillance stakeholders to seek agreement on improving surveillance methods in SOF. Iterative questionnaires using close and open-ended questions were used to collect views about surveillance methods related to injury case definitions and identifying essential and optional data requirements. Consensus was predefined as 75% group agreement on an item. Sixteen participants completed two rounds of questionnaires required. Consensus was achieved for 17.9% (n = 7) of questions in the first-round and 77.5% (n = 38) of round two questions. Several challenges for surveillance were identified, including recording injury causation, SOF personnel's injury reporting behaviours influencing accurate data collection, and surveillance system infrastructure limitations. Key military injury surveillance stakeholders support the need for improved data collection to enhance the evidence that underpins injury prevention efforts. The consensus process has resulted in preliminary recommendations to support future SOF injury surveillance.