Incidence and Mechanisms of Musculoskeletal Injuries in Deployed Navy Active Duty Service Members Aboard Two U.S. Navy Air Craft Carriers

Differences in Musculoskeletal Injury and Disability Rates in U.S. Navy Sailors Aboard Aircraft Carrier and Amphibious Assault Ships

INTRODUCTION

Musculoskeletal injuries (MSKI) are the most common clinical condition in the military that affect medical readiness. Evaluation of MSKI burden and the effects of these injuries on readiness in large deck Navy ships is warranted.

MATERIALS AND METHODS

A retrospective cohort study assessing population-level MSKI rates, short-term disability (restricted duty), and long-term disability episode counts of all Sailors assigned to U.S. Navy Aircraft Carriers (CVNs) and Amphibious Assault Ships (LHA/LHD) from November 2016 to February 2023 was extracted from the Musculoskeletal Naval Epidemiological Surveillance Tool. A negative binomial regression and general additive (Gaussian) models evaluate the association of ship platform, deployment status, days underway, and sex with MSKI rates and the proportion of cases that resulted in short-term disability, returned-to-duty following restricted duty, or progressed to long-term disability.

RESULTS

Sailors attached to CVNs contributed a mean 17,893.8 ± 23,280.6 person-months, with those attached to LHA/LHDs contributing an average 5,981.8 ± 8,432.7 person-months. Aboard CVNs, MSKI occurred at a rate of 0.30 ± 0.16/1,000 person-months while deployed and 0.64 ± 0.31/1,000 person-months in homeport. Aboard LHA/LHDs, Sailors incurred MSKI at a rate of 0.59 ± 0.58/1,000 person-months while on deployment and 1.24 ± 0.68/1,000 person-months in homeport. Among Sailors aboard CVNs, short-term disability occurred in 7.95 ± 7.75% of MSKI cases while deployed and 5.13 ± 5.26% while in homeport. Aboard LHA/LHDs, 8.57 ± 13.42% of MSKI cases were placed on short-term disability while deployed and 4.95 ± 5.27% while in homeport. In the multivariable assessment of short-term disability, being deployed underway was a significant factor (B = 3.62 P = .03, variance explained = 3.86%). Sailors that were female and served aboard LHA/LHDs returned to full duty at a significantly greater frequency compared to their male counterparts and Sailors serving aboard CVNs. None of the independent variables evaluated were associated with long-term disability.

CONCLUSION

The findings in the current study demonstrate the substantial burden of MSKI aboard large deck ships, both in homeport and while deployed. Inclusion of a physical therapist aboard LHA/LHDs, like the CVN, may help to prevent and mitigate the effects of MSKI through early access to specialized care and integral injury prevention and performance optimization methods.

Musculoskeletal Complaints Among Active Duty Service Members Seeking Treatment at a Navy Military Treatment Facility

INTRODUCTION

Musculoskeletal injuries (MSIs) pose a significant problem for active duty service members (ADSMs). MSIs may compromise readiness and are one of the main reasons for separation from the Navy and long-term disability. Implementation of optimal treatment strategies rests on understanding the characteristics of MSI complaints in a given population. This study reports on the frequency and nature of MSI complaints of ADSMs seeking care at a military treatment facility (MTF).

MATERIALS AND METHODS

As part of a larger quasi-experimental study, data on MSIs from ADSMs reporting to an MTF were collected. Subjects completed a baseline questionnaire during an initial evaluation, including the self-reported MSIs for which participants were seeking care, time since onset, and other MSI comorbidities.

RESULTS

Of the 289 respondents, 118 (41%) were female and 172 (59%) were male. The mean age was 33 years (SD = 8). The most frequently reported injury was low-back pain (n = 79, 27%), followed by knee pain (n = 60, 21%) and shoulder pain (n = 55, 19%). Thirty-four (12%) respondents reported injuries to the ankle or foot. The remaining respondents (21%) reported injuries to the neck, mid-back, arm or hand, hip, or other. Sixty-five (22%) reported an acute/subacute injury of less than 3 months, whereas 224 (78%) reported chronic injury >3 months. Furthermore, MSI comorbidities were reported by 233 (80%) of respondents with 128 of those reporting more than one.

CONCLUSIONS

Back and knee injuries were most prevalent in ADSMs reporting an MSI at a Navy shore-based MTF. Shoulder injuries were also common. Of interest, 80% of ADSMs reported at least one MSI comorbidity and 80% reported chronic injury in this study. These rates are higher than those found in a previous study of ADSMs deployed on a carrier. This is notable because chronicity and multiple MSIs are obstacles to readiness. Our findings suggest that ADSMs reporting to shore-based facilities may be at higher risk for disability than their deployed counterparts. This information is important to the development of targeted care to improve readiness in this population.

Sex differences in musculoskeletal injury epidemiology and subsequent loss of tactical readiness during Marine Corps Officer Candidates School

INTRODUCTION

The US Marine Corps (USMC) Officer Candidates School (OCS) is a 10-week training course for Marine Officer Candidates (MOCs). OCS training is rigorous and demanding, which results in a high risk of musculoskeletal injuries (MSIs). The objective of this analysis was to describe MSIs among women and men during the USMC OCS at Quantico, Virginia, from September 2020 to November 2021.

METHODS

This prospective cohort study assessed MSIs that occurred among 736 MOCs (women: 17.8% of sample, men: 82.2%). Data for the study were derived from routinely collected injury data by athletic trainers and physical therapists embedded within the training units. Injury incidence, event at the time of injury occurrence, anatomic location, injury type and disposition following injury were described. Fisher's exact tests were used to compare proportions of injured women and men.

RESULTS

The cumulative injury incidence was higher among women (39.7%) compared with men (23.1%, p<0.001). When specific events associated with injuries were reported, most frequent events were the obstacle course (women: 20.9% of injuries, men: 12.9%) and the conditioning hike (women: 11.6%, men: 6.9%). Most injures affected the lower body (women: 67.4%, men: 70.8%). The most frequent body part injured was the lower leg (18.6%) in women and the knee (23.3%) in men. The most frequent injury type was strain (women: 39.5%, men: 24.3%), followed by sprain (women: 16.3%, men: 14.9%). A greater percentage of female (92.3%) compared with male MOCs (69.3%; p<0.001) were assigned light duty status following MSIs.

CONCLUSIONS

Mitigation of injuries during OCS events such as the obstacle course and the conditioning hike needs further investigation. The high risk of overuse lower leg injuries among women and the higher incidence of injuries among women compared with men underscore the need for further investigation of modifiable sex-specific injury risk factors.

Epidemiology of Musculoskeletal Injuries in the Navy: A Systematic Review

Objectives: This study aimed to critically review the results of recent studies that investigated the epidemiology of noncombat-related musculoskeletal injuries (MSIs) in the Navy. Methods: A systematic search was conducted of three major databases (Pubmed, Embase, and Cochrane) to identify epidemiological studies on MSIs in the Navy. Study selection and risk of bias assessment were conducted. Results: The overall prevalence of MSIs ranged from 12.69% to 48.81%. And the prevalence of head and face injuries, upper extremity injuries, spine injuries, chest injuries, and lower extremity injuries were 0.11%-0.66%, 0.53%-11.47%, 0.75%-12.09%, 0.43%-0.95%, and 0.4%-21.17%, respectively. For the specific MSIs, the incidence ranged from 0.03/1000 person-years to 32.3/1000 person-years in the Navy and Marines. The ankle-foot, lumbopelvic, knee and lower leg, and shoulder were identified as the most frequent location for MSIs. Conclusion: This systematic review summarized that the Navy population had a high prevalence of MSIs. And different risk factors for MSIs varied from different anatomic locations. This systematic review also provided valuable information on MSIs for sports medicine specialists.

Sex Differences in the Incidence and Risk of Ankle-Foot Complex Stress Fractures Among U.S. Military Personnel

Background: The objective of this study was to evaluate sex differences in the incidence and risk of ankle-foot complex (AFC) stress fractures among U.S. military personnel, which could assist in developing management strategies as females assume a greater role in U.S. military operations. Materials and Methods: The Defense Medical Epidemiology Database was used to identify all diagnosed AFC stress fractures in military personnel from 2006 to 2015. Cumulative incidence of AFC stress fractures was calculated and compared by year, service branch, and military rank. Sex differences in the risk of AFC stress fractures by occupation were examined, and integrated (i.e., male and female) occupations were compared with nonintegrated (i.e., male only) occupations. Results: A total of 43,990 AFC stress fractures were identified. The overall incidence rate was 2.76 per 1,000 person-years (p-y) for males and 5.78 per 1,000 p-y for females. Females consistently had higher incidence of AFC stress fractures across all subgroups, particularly among enlisted personnel. Female enlisted service members had the highest risk of AFC stress fractures in aviation (relative risk [RR] = 5.74; 95% confidence interval [CI]: 4.80-6.87) and artillery/gunnery (RR = 5.15; 95% CI: 4.62-5.75) occupations. Females in integrated occupations had significantly higher rates of AFC stress fractures than males in both integrated and nonintegrated occupations (i.e., special forces, infantry, and mechanized/armor). Conclusions: Females in the U.S. military have a higher risk of AFC stress fractures than males. As integration of females into previously sex-restricted occupations continues, focused prevention efforts may be needed to reduce injury burden and maximize medical readiness.

The effects of ergonomic intervention on the musculoskeletal complaints and fatigue experienced by workers in the traditional metal casting industry

This research aimed to evaluate the effects of ergonomic intervention on the musculoskeletal complaints and fatigue experienced by workers of the traditional metal casting industry that manually pour molten metal into molds. The workers' physical complaints are typically in the form of musculoskeletal complaints, which include (1) an activity aspect, (2) a physical aspect, and (3) a motivational aspect. The method used in this research was stratified random sampling. The subjects (n = 127) were divided into three groups, namely, the process cement department (PCD) group, the loam department (LD) group, and the black sand department (BSD) group. The evaluation was carried out using questionnaires based on musculoskeletal complaints and fatigue. Meanwhile, an assessment of musculoskeletal complaints and fatigue was conducted one month before the ergonomic intervention, and then during follow-ups at one and eight months after the ergonomic intervention. The results showed that the average reduction in musculoskeletal complaints and fatigue experienced by the workers in the LD group was lower than that of the workers in the PCD and BSD groups at one and eight months after the ergonomic intervention. The positive effects of the ergonomic intervention on musculoskeletal complaints were evident in terms of the back, waist, left and right thighs, right knee, right ankle, and left foot (p < 0.05). The positive effects of the ergonomic intervention on the level of activity-based fatigue were felt in the body and legs, and the feeling of wanting to lie down decreased. The motivational fatigue experienced by the workers manifested as difficulty in thinking, concentrating, and controlling behavior, while the physical fatigue experienced by the workers was in the form of headaches, back pain, excessive thirst, and feeling unwell (p < 0.05). It can be concluded that ergonomic intervention can reduce both musculoskeletal complaints and fatigue, especially by conducting a morning briefing, using ergonomic ladles when pouring molten metal into molds, and consuming nutritious food during break times.