Abstract
Purpose
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In the military, neck pain is second to low back pain among musculoskeletal disorders. However, the prevalence and related factors of neck pain in military personnel have not been systematically investigated, which may lead to the lack of neck pain prevention and the generation of additional medical expenses, posing challenges to medical care. This review aimed to obtain the prevalence and related factors for neck pain in military personnel in an attempt to provide directions for prevention and intervention.
Methods
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We searched PubMed, Embase, and Cochrane databases in December 2021. Two researchers independently screened studies according to eligibility criteria and assessed study quality.
Results
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We screened titles and abstracts of 503 articles, and 17 articles met the inclusion criteria. Sixteen articles received moderate to high-quality evaluations. Neck pain is common in the military, with 1-year prevalence as high as 83% and lifetime prevalence as high as 78%. Old age (OR = 5.0), poor neck mobility (OR = 3.61), shoulder pain (OR = 4.9), low back pain (OR = 2.3), high-G pilots (OR = 1.6), longer flight time (OR = 2.53), type of aircraft (OR = 3.93), and use of helmets and night vision systems (OR = 1.9) may be associated with the prevalence of neck pain.
Conclusion
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Neck pain is highly prevalent in military personnel and exhibits a substantial lifetime prevalence rate. The high prevalence rate of neck pain in the military is related to many individual-related factors and work-related factors. The in-depth assessment and prevention of specific factors is an important direction of future research.
Introduction
Pain stemming from chronic musculoskeletal disorders (MSD) represents a significant contributor to disability, impacting 30% of the global population (1). Neck pain is well known as a common MSD. The global age-standardized point prevalence of neck pain was estimated at 3.551% in 2017, ranking it as the fourth leading cause of disability worldwide (2, 3). The prevalence of neck pain is high in the military, ranking second after low back pain in MSD prevalence (4, 5). Disabling neck pain is more common in the military (6). Meanwhile, neck pain is one of the main reasons for missed deployments and medical evacuations (7). In the pilot population, reporting neck discomfort may result in a lost workday, and being considered temporarily unfit to fly (8). Considering the overall cost of training combat personnel, these factors may lead to significant financial expenditures (9).
Existing articles have extensively studied the prevalence and related factors of MSD in military personnel, with pain in the spinal region receiving increasing attention as the disease type with the highest incidence (10). A cross-sectional study on fighter jet crew members revealed a staggering 97% prevalence of neck pain throughout their careers (11). However, research specifically addressing neck pain among military personnel remains scarce. Particularly, outside the Air Force, the prevalence and factors associated with neck pain among military personnel are poorly elucidated.
Several social population-based studies have explored related factors for neck pain. Factors such as advanced age, female gender, smoking, poor psychological and general health, lower social support, and a history of neck or lower back pain were mentioned in these studies (12, 13, 14, 15). Due to the specific content and duties of the profession, military personnel may be subjected to greater physical and psychological stress than the general population, and these stresses may cause neck pain to manifest more severely (7). In studies focusing on Air Force personnel, G-force, flight hours, wearing of helmet equipment, and exposure to adverse postures are often cited as potential factors for neck pain (11, 16, 17, 18).
Existing articles have extensively studied the prevalence and related factors of MSD in military personnel, with pain in the spinal region receiving increasing attention as the disease type with the highest incidence (10). Identification of pain-related factors, implementation of prevention, and early intervention are necessary, considering the negative impact of neck pain on individual health and operational deployment. To our knowledge, most existing systematic reviews have examined the prevalence and related factors of neck pain in the Air Force and do not cover other branches of the military. This review focuses on active-duty military personnel of all services. The objective is to identify the prevalence of neck pain among military personnel, integrate existing evidence on factors associated with the occurrence of neck pain, and provide recommendations for prevention and intervention.
Methods
In completing this review, PRISMA guidelines were followed. The protocol for the review was registered in the OSF (https://osf.io/23ysw), and the registration DOI was 10.17605/OSF.IO/23YSW.
Search Strategy
A comprehensive search of the literature on neck pain in military personnel was conducted. Three electronic databases, including PubMed, Embase, and Cochrane, were searched up to 19 December 2021. Search terms were a combination of military, soldier, neck pain, and cervical pain (see Supplementary Material for details). We made synonym substitutions for these terms to improve search sensitivity and avoid omissions. We tailored the terms based on the thesaurus of each database. The study’s relevance was checked based on the title and abstract, and articles that were completely irrelevant to the content of the study were excluded. We also performed a secondary search of the studies of included articles to ensure that all relevant literature studies were searched.
Study Selection
Titles, abstracts, and full texts were screened by a researcher based on the following pre-established eligibility criteria. Discussions between the two researchers were used to resolve any disputes during screening, and a third researcher was consulted during disagreements.
Studies that satisfied the following criteria were eligible for inclusion: i) subjects were active-duty military personnel (combatants and non-combatants); ii) a cross-sectional study was designed; iii) studies describing the prevalence of neck pain, explicitly reporting the time frame for which the prevalence was calculated; iv) studies describing the related factors for neck pain, the odds ratios (ORs), risk ratios (RRs), or hazard ratios (HRs) were reported for related factors; v) studies that simultaneously describe the prevalence and related factors of neck pain; vi) the study is complete and published in English.
Studies were excluded for the following reasons: i) mainly discussing the treatment and intervention of neck pain; ii) no separate categories of studies for neck pain; iii) studies in populations with specific underlying pathologies were excluded (e.g., tumors, fractures, infections, inflammatory diseases, and osteoporosis); iv) the small sample size of the report makes it difficult to obtain enough data for analysis; v) letters, abstracts, books, meeting minutes, and posters were excluded in the review.
Data Extraction
Two researchers used standardized tables to extract information for each study, such as the year of study publication, author information, study design, sample size, mean age of participants, prevalence, and definition of pain for each study, to determine the parity and differences between studies. Any conflicts were resolved through negotiation. The outcomes focused on were prevalence, pain-related factors for associated injuries, and pain-related factor reporting (ORs, RRs, or HRs). If studies did not report prevalence directly, we calculated it by extracting article information.
Study Quality Assessment
The quality of the included literature was assessed using the criteria recommended by the Agency for Healthcare Research and Quality (AHRQ) for evaluating cross-sectional studies. This quality assessment checklist has 11 items, including data sources, formulation of inclusion and exclusion criteria, time period, whether subjects are continuous, the objectivity of indicators, reproducibility of indicators, reasons for excluding subjects, control for confounders, handling of missing data, whether to summarize response rates, and follow-up. An item would be scored ‘0’ if the answer is ‘NO’ or ‘UNCLEAR’; if it was answered ‘YES’, then the item is scored ‘1’. We considered studies with ≤ 3 scores as low quality, 4–7 scores as medium quality, and ≥ 8 scores as high quality (19, 20).
Results
Study Selection
A total of 503 relevant literature records were retrieved from three databases. After duplicates were removed, 363 papers remained. Titles and abstracts were screened by a researcher based on pre-established eligibility criteria. A total of 59 original articles were read and screened by two researchers, and 17 articles were included in the review (Fig. 1).
PRISMA flowchart for study selection.
Citation: EFORT Open Reviews 9, 8; 10.1530/EOR-23-0150
Study Quality
The methodological quality analysis of the included literature was carried out using the quality assessment checklist recommended by the Agency for Healthcare Research and Quality (AHRQ). Three of the 17 articles scored 8–9 points as high-quality research, one of the 17 articles scored 3 points as low-quality research, and 13 scored 4–7 points as medium-quality research. The quality scores for each study are detailed in Table 1.
The AHRQ quality assessment checklist scores for included studies.
| Included studies | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (23) | (28) | (29) | (18) | (22) | (26) | (30) | (24) | (31) | (21) | (32) | (33) | (34) | (27) | (11) | (25) | (35) | |
| Define the source of information | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| List inclusion and exclusion criteria for exposed and unexposed subjects or refer to previous publications | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| Indicate time period used for identifying patients | Y | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | N | Y | Y |
| Indicate whether or not subjects were consecutive if not population-based | Y | N | Y | N | Y | Y | Y | N | Y | Y | Y | Y | Y | Y | N | Y | Y |
| Indicate if evaluators of subjective components of study were masked to other aspects of the status of the participants | N | Y | Y | N | N | N | N | N | N | N | N | N | N | N | N | N | N |
| Describe any assessments undertaken for quality assurance purposes | N | N | Y | N | Y | N | Y | N | N | N | N | N | N | N | N | Y | N |
| Explain any patient exclusions from analysis | N | N | N | N | Y | N | Y | N | N | N | N | N | N | N | Y | Y | N |
| Describe how confounding was assessed and/or controlled | N | N | Y | N | N | N | Y | N | N | N | N | N | N | N | N | Y | N |
| If applicable, explain how missing data were handled in the analysis | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | Y | N |
| Summarize patient response rates and completeness of data collection | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| Clarify what follow-up was expected and the percentage of patients for which incomplete data or follow-up was obtained | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N | N |
| Summary of research quality | Med | Med | High | Low | Med | Med | High | Med | Med | Med | Med | Med | Med | Med | Med | High | Med |
AHRQ, Agency for Healthcare Research and Quality; med, medium; Y, yes; N, no or unclear.
Study Characteristics
This review identified 17 studies through screening, and Table 2 shows the basic characteristics of the included studies. Among the 17 studies included in the review, 12 described the prevalence of neck pain in pilots and flight crews, six described the related factors of neck pain in pilots and flight crews, one described the prevalence and related factors of neck pain in military office personnel, one described the prevalence and related factors of neck pain in the main battle tank units, one study had data from Army units, one study had data from Marine Corps, and one study collected aggregate information across multiple units. All studies were cross-sectional; two studies obtained data from information databases (21, 22), and the remaining studies obtained data in the form of questionnaires. A total of 1 318 688 military personnel from three regions (US, Europe, and Asia) participated in the study, with study sizes ranging from 58 to 1 296 881, all without follow-up. Only seven studies included small numbers of female subjects. Fourteen studies have a clear definition of neck pain, ranging from a low threshold description such as ‘……any physical complaints or injuries during the previous 12 months and/or at present,’ through a higher threshold description, such as ‘…derived from an ICD-9 to ICD-10 pain condition crosswalk’ and ‘disc herniation or protrusion, disc degeneration, and/or spondylosis.’ Six studies provided short-term prevalence (1-week to 6-months), and 14 studies provided long-term prevalence (1- year to lifetime).
Summary of the included studies.
| Study | Subjects | Definition of neck pain | Prevalence | |||
|---|---|---|---|---|---|---|
| n | Age, years | Country | Occupation | |||
| 23 | 629 | <30: 6% | Belgium | Office worker | ‘Neck pain was defined as pain in the head and neck region, shades in a drawing of the head, neck and shoulder area’ | 53% (1 week); 65% (1 year); 78% (lifetime) |
| 30–39: 33% | ||||||
| 40–49: 49% | ||||||
| >50: 11% | ||||||
| 28 | 63 | 30 (24–39) | S Korea | Air Force pilot | Not specified | 50.7% (1 year) |
| 29 | 73 | 39 ± 8 | Sweden | Air Force personnel | ‘…any physical complaints or injuries during the previous 12 months and/or at present’ | 56% (1 year) |
| 18 | 70 | F-16: 32.54 ± 4.71 | Italy | F-16 pilot: n = 35 | ‘Neck pain was defined as at least two episodes of neck pain after flight in the last 2 months’ | 48.6% for F-16 group (2 months) |
| Typhoon: 33.37 ± 3.84 | Typhoon pilot: n = 35 | 5.7% for Typhoon group (2 months) | ||||
| 22 | 19,673 | ≥ 40: 31.9% | USA | HPA pilot: n = 5681 | ‘…the primary diagnosis was related to a cervical or lumbar intervertebral disc bulge, disc herniation or protrusion, disc degeneration, and/or spondylosis’ | 0.52% (lifetime) |
| ≤ 39: 68.1% | RWA pilot: n = 719 | |||||
| FWA pilot: n = 13273 | ||||||
| 26 | 221 | 44.7 ± 8.4 | Austria | Helicopter pilots: n = 104 | ‘…we defined pain as any reported pain experience, ache or discomfort’ | 67.3% for helicopter pilots (1 year) |
| Crew members: n = 117 | 45.3% for crew members (1 year) | |||||
| 30 | 184 | < 30: 68.5% | Denmark | Army* | Not specified | 36.4% (1 year) |
| ≥ 30: 31.5% | ||||||
| 24 | 195 | HQ: 39 ± 6 | Finland | Military pilots | ‘…cervical spine pain must have appeared after the commencement of active military flying…preclude prolonged or sustained high-performance military flying’ | 34% for HQ group (6 months) |
| low-G: 34 ± 7 | 60% for low-G group (6 months) | |||||
| high-G: 30 ± 5 | 61% for high-G group (6 months) | |||||
| 31 | 105 | 20–29: n = 47 | Norway | Fighter pilots | ‘Neck pain events in general and specifically in the last 12 months’ | 50% (1 year) |
| 30–39: n = 45 | ||||||
| > 40: n = 13 | ||||||
| 21 | 1,296,881 | not specified | USA | Army, Navy, Air Force, Marines | ‘…derived from an ICD-9 to ICD-10 pain condition crosswalk’ | 2.99% (1 year) |
| 32 | 61 | < 30: 34% | Netherlands | Military helicopter cabin crew | ‘Neck pain was defined as any pain, including aches and discomfort…’ | 28% (1 year) |
| 30–40: 39% | ||||||
| 40–55: 27% | ||||||
| 33 | 113 | < 30: 41 | Netherlands | Military helicopter pilots | ‘Neck pain was defined in the questionnaire as any pain, including aches and discomfort in the previous 12 months’ | 43% (1 year) |
| 30–40: 51 | ||||||
| 40–55: 21 | ||||||
| 34 | 58 | < 30: 29% | Netherlands | F-16 pilots | ‘Pain was defined as any pain or discomfort’ | 22% (1 year) |
| 30–40: 46% | ||||||
| 40–55: 25% | ||||||
| 27 | 373 | < 25: 23% | Poland | Army soldiers* | Not specified | 21% (1 year) |
| 25–40: 57% | ||||||
| > 40: 20% | ||||||
| 11 | 58 | 20–29: 15 | Denmark | F-16 pilots | ‘…experienced neck pain during or immediately after flight’ | 83% (1 year) |
| 30–39: 40 | ||||||
| > 40: 3 | ||||||
| 25 | 272 | 25.3 ± 6.7 | Sweden | Marines | ‘Musculoskeletal pain was defined as any self-reported episode of pain within the past 6 months’ | 19.5% (6 months) |
| 35 | 90 | Not specified | Belgium | F-16 pilots | ‘Neck pain was defined as pain in the head and neck region’ | 18.9% (1 year) |
DOB, date of birth; FWA, other fixed-wing aircraft; HPA, high-performance aircraft; HQ, headquarters’ posts; RWA, rotary-wing aircraft.
*Main battle tank (MBT) units of the army.
Prevalence
Six studies reported short-term prevalence of neck pain ranging from 5.7% to 64.4% (18, 23, 24, 25, 26, 27), and 14 studies reported long-term prevalence ranging from 0.52% to 83% (11, 21, 22, 23, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35). The 1-year prevalence among military personnel in the Office of Defense is 65% (23). Marines in the Navy reported a 6-month prevalence of 19.5% (25). The 1-year prevalence in Army units ranges from 21% to 36.4%, including 21% in Army units and 36.4% in Main Battle Tank units (27, 30). The 1-year prevalence in the Air Force ranged from 18.9% to 83% (11, 26, 28, 29, 31, 32, 33, 34, 35). Among them, the 1-year prevalence rate of high-performance fighter pilots was 18.9–83%, the 1-year prevalence was 43–67.3% for helicopter pilots, and 28%–45.3% for crew members.
Of the 17 included studies, 14 articles described the prevalence of neck pain in the European military, and the three remaining studies described the US and South Korean military. According to reports, 2502 subjects, including fighter pilots, helicopter pilots, aircrews, army personnel, marines, main battle tank units, and military office personnel, were included in the study of the European military. The 1-year prevalence rate of neck pain was 18.9–83%, and the lifetime prevalence is as high as 78%. Both studies on the U.S. military used information from medical information databases. A total of 1 316 554 people’s medical information was counted. Using the International Classification of Diseases (ICD-9 and ICD-10) as the standard, the subjects covered the army, navy, air force, and marines, and finally reported a neck pain prevalence rate of 0.52%–2.99%.
According to the data from the included studies, most subjects were between 30 and 40 years old. The mean age of participants in the two studies was over 40 years, and these studies reported a 1-year prevalence of 65% and 67.3%, which were high among the included studies (23, 26). The two studies with the youngest mean age of subjects reported prevalences of 36.4% and 19.5% (25, 30).
Individual-Related Factors Associated with Neck Pain
In individual-related factor reports, no significant associations were found for height, weight, and body mass index (BMI). All studies collected age data of the subjects, and two studies did not report the association of neck pain with age. Among the remaining six studies, two found that neck pain was significantly associated with age (Table 3). One study found that neck pain was associated with ages over 30 among F-16 pilots (RR: 3.11, 95% CI: 1.123–12.139) (18). Another study indicated a significant correlation between ages over 40 and neck pain (OR: 5.0, 95% CI: 3.28–7.63). Military rank and marital status were also analyzed as pain-related factors in this study, with being married as a related factor (OR: 2.92, 95% CI: 1.85–4.51) (22). One study reported an association between gender and military neck pain, but no significant results were obtained (22).
Summary of significant related factors for neck pain in military personnel.
| Related factors | OR/RR | 95% CI | Study | |
|---|---|---|---|---|
| Movement control | 29 | |||
| Neck flexion in sitting – uncontrolled | 3.61 | 1.06–12.34 | ||
| Forward lean – uncontrolled | 3.43 | 1.04–11.37 | ||
| Range of motion | Neck flexion (degrees) | 0.93 | 0.87–0.99 | 29 |
| Spine morphology | C2-7 ARA | 0.910 | 0.846–0.979 | 28 |
| Adjacent joint pain | 26 | |||
| Shoulder pain (yes) | 4.9 | 2.48–9.55 | ||
| Low back pain (yes) | 2.3 | 1.21–4.31 | ||
| Age | ||||
| Birth year ≤ 1966 (age over 40 years) | 5.0 | 3.28–7.63 | 22 | |
| Age over 30 years | 3.11* | 1.123–12.139 | 18 | |
| Marriage | Married | 2.92 | 1.85–4.51 | 22 |
| Work-related posture and fatigue | 23 | |||
| Being physically tired after a normal working day (short term) | 1.58 | 1.42–1.73 | ||
| Working in a bent or twisted posture for a prolonged time (short term) | 1.62 | 1.39–1.84 | ||
| Working in a bent or twisted posture for a prolonged time (long term) | 2.64 | 2.30–2.97 | ||
| Working in the same posture for a prolonged time (long term) | 1.77 | 1.47–1.82 | ||
| Work-related psychosocial factors | 23 | |||
| Being dissatisfied in the current job (short term) | 2.22 | 2.05–2.38 | ||
| Being mentally tired after a normal working day (short term) | 1.80 | 1.64–1.95 | ||
| Unfavorable prospects employer (short term) | 1.66 | 1.37–1.95 | ||
| Being rather dissatisfied in the job (long term) | 1.61 | 1.40–1.82 | ||
| Being mentally tired after a normal working day (long term) | 1.83 | 1.63–2.02 | ||
| Flight hour | ||||
| Total flight hours (F-16 group) | 3.11* | 1.123–12.139 | 18 | |
| Flight hours on the F-16 exceeding 600 | 2.44* | 1.087–4.992 | 18 | |
| Flight hours ≥ 2000 | 2.53 | 1.42–4.51 | 22 | |
| Aircraft type | ||||
| Fighter type | 3.930 | 1.104–13.989 | 28 | |
| Aircraft type (F-16) | 5.0* | 1.324–30.932 | 18 | |
| G-force | High-G group | 1.6 | 1.02–2.70 | 24 |
| NVG | NVG use (yes) | 1.9 | 1.06–3.50 | 26 |
| Rank | Rank: Maj–Col | 4.66 | 2.73–7.95 | 22 |
ARA, absolute rotation angle; NVG, night vision goggles; OR, odds ratio; RR, risk ratio.
*Values are RR.
In addition to basic information, further research on neck pain includes morphology under radiation, range of motion (ROM), movement control, muscle isometric strength and endurance, and pain in adjacent joints. Lateral and whole-spine radiographs showed that the proportion of pilots with neck pain was 82% among pilots with cervical kyphosis (P = 0.029), and this figure was 50% and 41.7% among pilots with straight and lordotic spines, respectively. One study evaluated the absolute rotation angle (ARA) of C2–7 on radiographs using the posterior tangent method and found that increasing the ARA of C2-7, that is, improving cervical kyphosis, reduced the possibility of neck pain (OR: 0.910, 95% CI: 0.846–0.979) (28). Another study conducted physical performance tests on the subjects and found a significant relationship between neck pain in cervical spine ROM and motor control. Impaired control of neck flexion (OR: 3.61, 95% CI: 1.06–12.34), poor control of trunk anteversion (OR: 3.43, 95% CI: 1.04–11.37), and limited range of motion in the neck flexion (OR: 0.93, 95% CI: 0.87–0.99) have been identified as related factors for cervicothoracic pain (29). Tests of neck flexors and extensors did not yield significant results in isometric strength and endurance testing. Shoulder pain (OR: 4.9, 95% CI: 2.48–9.55) and low back pain (OR: 2.3, 95% CI: 1.21–4.31) that occurred in the past 12 months were also independent related factors for neck pain (26).
Work-Related Factors Associated with Neck Pain
Among work-related factors, seven studies described occupational associations with neck pain, including flying different types of aircraft and holding different positions in the military. In aircraft-specific comparisons, F-16 pilots and typhoon fighter pilots showed significant differences in neck pain prevalence (62.5% vs 12.5%, RR: 5.5, 95% CI: 1.324–30.932) (18). One study compared actively flying high-G aircraft pilots with inactive flying headquarters staff. The results showed a higher prevalence of neck pain in the high-G group (OR: 1.66, 95% CI: 1.02–2.70) (24). Fighter pilots had a higher prevalence of neck pain (84.4% vs 61.3%, OR: 3.930, 95% CI: 1.104–13.989) than non-fighter pilots (28). In a study involving neck pain in helicopter pilots, more helicopter pilots suffered from neck pain than crew members (67.3% vs 45.3%, OR: 2.5, 95% CI: 1.44–4.30) (26). Four studies discussed the association of flight duration with pilot neck pain, with two studies showing significant results. More than 2000-h of fighter flight time increased the risk of neck pain in pilots (OR: 2.53, 95% CI: 1.42–4.51) (22). Night vision goggles (NVG) use is a factor of frequent concern, but only one study identified NVG use as an independent related factor for neck pain in pilots (OR: 1.9, 95% CI: 1.06–3.50) (26).
In a study of military personnel in offices, physical exhaustion after a working day, working in a bent or twisted position for long periods, and maintaining the same posture were identified as possible factors for the development of neck pain. The study also discusses psychological factors related to work, mental exhaustion after a working day, and dissatisfaction with work may contribute to neck pain (Table 3) (23).A study found that a military ranking above major has a higher risk of neck disease (OR: 4.66, 95% CI: 2.73–7.95), which may be similar to the age factor discussed earlier (22). The summary of neck pain-related factors based on the classification of military branches can be found in the Additional table (see section on supplementary materials given at the end of this article).
Discussion
This review aimed to investigate the prevalence and related factors for neck pain in military personnel. From an analysis of the included studies, we found a high prevalence of neck pain in military personnel. Among the studies included in this review, the 1-year prevalence of neck pain was as high as 83%, and the lifetime prevalence was as high as 78%, much higher than that of the general adult population. A review revealed that the overall prevalence of neck pain in the general population averages 23.1%, with a 1-year prevalence averaging 25.8% (36). Among general adults and workers, the 1-year prevalence of neck pain ranges from 12.1% to 71.5% (13). Two cross-sectional studies from Korea and Sweden reported neck pain in middle-aged and elderly populations, with a lifetime prevalence of 20.8% and a 1-year prevalence of 29%, respectively (37, 38). A study based on the UK population investigated the prevalence of neck pain across different occupations, revealing that construction workers, nurses, and armed forces personnel have the highest prevalence of neck pain (6). In general, similar to previous studies, the military population has a higher incidence of neck pain, which may be due to the higher physical burden and psychosocial stress of the military occupation (7).
Neck pain is widespread in the military population, and the army (21%), tank units (36.4%), marines (19.5%), and military office personnel (65%) have reported the corresponding prevalence of neck pain. By contrast, the Air Force has a higher prevalence of neck pain, with a 1-year prevalence of 18.9%–83%. There are significant differences in the prevalence of neck pain among various studies. First, there are variations in the definition of neck pain across studies, with no uniform standard established for localizing the region of the neck, or the reports are unclear. Secondly, different studies employ different types of data, including self-reported data, medical records, or clinical diagnosis data, which vary in accuracy. Additionally, there is diversity in data collection methods, with some studies using relatively strict ICD classifications while others rely on subjective questionnaires based on recall. These reasons may contribute to the potential causes of variation in prevalence rates.
We noted that the age of the soldier, job function, work environment, spine morphology, musculoskeletal pain of the adjacent joints, and psychological factors were significantly associated with the occurrence of neck pain. Some studies suggest that older age is a related factor for neck pain in military personnel, and higher age may result in more than three times the odds of developing neck pain, which may be due to irreversible degenerative changes in the neck structure. Gender has also been defined as a related factor for the occurrence of neck pain, and some studies have suggested that females are a common related factor for neck pain (39). However, this difference is not reflected in the military population. This finding can be explained by the one-sidedness of the military. A growing number of studies have begun to analyze the relationship between psychosocial factors and the occurrence of disease. Studies suggest that psychosocial factors are associated with reported neck pain episodes and have a greater impact than physical factors. Frequent psychological fatigue may be a more important cause than occupational-related factors (6). In high-stress environments, such as in the military, neck pain appears to be more common. The advancement in military ranks and the transition from unmarried to married status often coincide with aging and an increase in work pressure and social stress. The combination of physiology and psychology may serve as an explanation for why military rank and marital status are considered factors associated with neck pain among military personnel.
Neck pain occurs more frequently in the Air Force than in other units, likely due to a harsher work environment and risk exposure. One study found that high-G pilots (high-performance aircraft pilots) had a 1.6-fold increased risk of neck pain compared with inactive flying groups (24). Exposure to 9G of gravitational acceleration may result in a 65 kg axial load on the cervical spine (40). In this state, helmet, NVG use, prolonged flight, and movement of the neck away from anatomical neutrality can place more stress on the cervical spine (11, 18, 41). The degenerative changes in the cervical spine and surrounding tissues caused by age may result in more evident pain. In the military office population, similar to the general office population, physical variables, such as constant posture and awkward posture, as well as psychosocial factors, such as low job satisfaction and mental fatigue, account for a significant portion of the related factors for neck pain. Main battle tank units do not exhibit higher neck symptoms than other infantry units, but serving as tank gunners is a risk for neck problems, possibly caused by maintaining the same position for extended periods(30).
Through the evaluation of literature quality, we found that the included literature has many deficiencies. First, a high proportion of research on neck pain is found in the Air Force, and high-quality research on related factors for neck pain in other arms is limited. Perhaps more high-quality studies in the future can fill this gap. Second, most studies used only questionnaires to obtain research data, and questionnaire surveys are subjective and may aggravate/reduce the description of pain levels over time. Moreover, some questionnaires lack validity and reliability. Among the 15 studies that used questionnaires, only 10 studies used validated questionnaires, and two studies conducted a detailed analysis of questionnaire use. If the validity and reliability of other questionnaires are unconfirmed, then the errors generated may impact the outcome indicators. Third, the descriptions of the neck vary among studies, with some studies defining this area with written descriptions, whereas others encouraged subjects to mark on a body chart where they experienced neck pain. Combined with the different definitions of neck pain in each study, the prevalence results were relatively different.
Limitations
Our review also has limitations. First, the scope of research in this review is relatively narrow, resulting in a limited number of studies meeting our inclusion criteria. Additionally, to gather more information on the prevalence and factors related to neck pain, we included as many relevant articles as possible. However, this may have led to higher heterogeneity among the studies, rendering them unsuitable for meta-analysis. Furthermore, we only included cross-sectional studies; thus, a causal relationship is less likely to be established. Although cross-sectional studies in military settings can achieve high response rates and continuity of study subjects, most studies also exhibit weaknesses in small sample sizes. Most articles included in the literature were obtained from studies in the USA and European countries because we did not include studies published in languages other than English due to translation issues. This condition leads to limitations in our data coverage. As we mentioned, the included literature has a high proportion from the Air Force, and high-quality studies from other arms are limited. We know that flight training often leads to more neck pain, thus this study may magnify the prevalence of neck pain in military personnel.
Implications
The neck pain among military personnel may be associated with various factors, including individual-related and work-related factors. Dealing with these factors will be the main direction of future research. The military may be able to check the neck through periodic assessments, especially for those who are older and have served longer. Early detection of abnormal spine morphology and degenerative changes may prevent neck pain earlier. To reduce the exposure of soldiers in high-G environments, on the one hand, an appropriate workload and training volume should be set to reduce exposure time. On the other hand, technological means are used to reduce the high gravity acting on the neck, such as designing seats that are more conformable to the body structure and using lightweight custom helmets. Psychosocial factors cannot be ignored either. The military should conduct regular questionnaires and formulate a psychological counseling mechanism. At the same time, military members are encouraged to maintain more active neck activity. Multiple studies on neck pain suggest that, in specific circumstances, nonsteroidal anti-inflammatory drugs (NSAIDs) and muscle relaxants can be beneficial for intervention, but in many cases, non-pharmacological treatments such as therapeutic exercises are preferred (42, 43). Currently, there are no specific management guidelines for military neck pain. However, based on existing guidelines, interventions such as neck ROM training, neuromuscular activities in the cervical spine and scapular region, manual therapy, endurance, flexibility, coordination, aerobic, and functional exercises, have higher levels of evidence support (44). Conducting a regular training program that includes cardio and neck-specific exercises is expected to help with muscular endurance and posture issues, thereby preventing and improving neck pain (45, 46).
Conclusion
This review indicated that neck pain is highly prevalent in the military, with a lifetime prevalence of up to 78%. Based on multiple cross-sectional studies of moderate to high quality, neck pain among military personnel may be associated with various factors, including age, job function, work environment, spinal morphology, other musculoskeletal pain, and psychosocial factors. Future research efforts should focus on improving the definition and assessment methods of neck pain, conducting cohort studies and cross-sectional surveys across different branches of the military, further exploring and validating potential risk factors, and ultimately developing prevention and intervention strategies.
Supplementary materials
This is linked to the online version of the paper at https://doi.org/10.1530/EOR-23-0150.
ICMJE Conflict of Interest Statement
The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the study reported.
Funding Statement
The authors disclosed receipt of financial support from the following for the study, authorship and/or publication of this article: the National Natural Science Foundation of China (fund no. 82372578); the scientific and technological research program of the Shanghai Science and Technology Committee (fund no. 19080503100; 21S31902400); the Shanghai Key Lab of Human Performance (Shanghai University of Sport, fund no. 11DZ2261100); Shanghai Clinical Research Center for Rehabilitation Medicine (fund no. 21MC1930200).
Availability of data and materials
All data generated or analyzed during this study are included in the published article.
Author contribution statement
LT and YHZ were major contributors in writing the manuscript. LT, YHZ, and SHD collected and analyzed the literature. XQW participated in critically revising the article. XQW received the funding for this study. All authors read and approved the final version of the manuscript.
References
- 1↑
Zheng YN, Liu H, Chen PJ, & Wang XQ. Association of persistent musculoskeletal pain with dementia risk score in adults aged 45 years or older: the China health and retirement longitudinal study. Brain, Behavior, and Immunity 2024 116 185–192. (https://doi.org/10.1016/j.bbi.2023.12.015)
- 2↑
Hoy D, March L, Woolf A, Blyth F, Brooks P, Smith E, Vos T, Barendregt J, Blore J, Murray C, et al.The global burden of neck pain: estimates from the global burden of disease 2010 study. Annals of the Rheumatic Diseases 2014 73 1309–1315. (https://doi.org/10.1136/annrheumdis-2013-204431)
- 3↑
Safiri S, Kolahi AA, Hoy D, Buchbinder R, Mansournia MA, Bettampadi D, Ashrafi-Asgarabad A, Almasi-Hashiani A, Smith E, Sepidarkish M, et al.Global, regional, and national burden of neck pain in the general population, 1990–2017: systematic a nalysis of the Global Burden of Disease Study 2017. BMJ 2020 368 m791. (https://doi.org/10.1136/bmj.m791)
- 4↑
Coleman BC, Goulet JL, Higgins DM, Bathulapalli H, Kawecki T, Ruser CB, Bastian LA, Martino S, Piette JD, Edmond SN, et al.ICD-10 coding of musculoskeletal conditions in the Veterans Health Administration. Pain Medicine 2021 22 2597–2603. (https://doi.org/10.1093/pm/pnab161)
- 5↑
Cohen SP, Gallagher RM, Davis SA, Griffith SR, & Carragee EJ. Spine-area pain in military personnel: a review of epidemiology, etiology, diagnosis, and treatment. Spine Journal 2012 12 833–842. (https://doi.org/10.1016/j.spinee.2011.10.010)
- 6↑
Palmer KT, Walker-Bone K, Griffin MJ, Syddall H, Pannett B, Coggon D, & Cooper C. Prevalence and occupational associations of neck pain in the British population. Scandinavian Journal of Work, Environment and Health 2001 27 49–56. (https://doi.org/10.5271/sjweh.586)
- 7↑
Cohen SP, Kapoor SG, Nguyen C, Anderson-Barnes VC, Brown C, Schiffer D, Turabi A, & Plunkett A. Neck pain during combat operations: an epidemiological study analyzing clinical and prognostic factors. Spine 2010 35 758–763. (https://doi.org/10.1097/BRS.0b013e3181bb11a8)
- 8↑
Tucker B, Netto K, Hampson G, Oppermann B, & Aisbett B. Predicting neck pain in Royal Australian Air Force fighter pilots. Military Medicine 2012 177 444–450. (https://doi.org/10.7205/milmed-d-11-00256)
- 9↑
Wallace JB, Newman PM, McGarvey A, Osmotherly PG, Spratford W, & Gabbett TJ. Factors associated with neck pain in fighter aircrew: a systematic review and meta-analysis. Occupational and Environmental Medicine 2021 78 900–912. (https://doi.org/10.1136/oemed-2020-107103)
- 10↑
Hauret KG, Jones BH, Bullock SH, Canham-Chervak M, & Canada S. Musculoskeletal injuries description of an under-recognized injury problem among military personnel. American Journal of Preventive Medicine 2010 38(1)(Supplement) S61–S70. (https://doi.org/10.1016/j.amepre.2009.10.021)
- 11↑
Lange B, Torp-Svendsen J, & Toft P. Neck pain among fighter pilots after the introduction of the JHMCS helmet and NVG in their environment. Aviation, Space, and Environmental Medicine 2011 82 559–563. (https://doi.org/10.3357/asem.2935.2011)
- 12↑
Genebra CVDS, Maciel NM, Bento TPF, Simeão SFAP, & Vitta AD. Prevalence and factors associated with neck pain: a population-based study. Brazilian Journal of Physical Therapy 2017 21 274–280. (https://doi.org/10.1016/j.bjpt.2017.05.005)
- 13↑
Hogg-Johnson S, van der Velde G, Carroll LJ, Holm LW, Cassidy JD, Guzman J, Côté P, Haldeman S, Ammendolia C, Carragee E, et al.The burden and determinants of neck pain in the general population: results of the Bone and Joint Dec ade 2000–2010 Task Force on Neck Pain and Its Associated Disorders. Spine 2008 33(4)(Supplement) S39–S51. (https://doi.org/10.1097/BRS.0b013e31816454c8)
- 14↑
McLean SM, May S, Klaber-Moffett J, Sharp DM, & Gardiner E. Risk factors for the onset of non-specific neck pain: a systematic review. Journal of Epidemiology and Community Health 2010 64 565–572. (https://doi.org/10.1136/jech.2009.090720)
- 15↑
Kim R, Wiest C, Clark K, Cook C, & Horn M. Identifying risk factors for first-episode neck pain: a systematic review. Musculoskeletal Science and Practice 2018 33 77–83. (https://doi.org/10.1016/j.msksp.2017.11.007)
- 16↑
Shiri R, Frilander H, Sainio M, Karvala K, Sovelius R, Vehmas T, & Viikari-Juntura E. Cervical and lumbar pain and radiological degeneration among fighter pilots: a systematic review and meta-analysis. Occupational and Environmental Medicine 2015 72 145–150. (https://doi.org/10.1136/oemed-2014-102268)
- 17↑
Chumbley EM, Stolfi A, & McEachen JC. Risk factors for cervical pain in F-15C pilots. Aerospace Medicine and Human Performance 2017 88 1000–1007. (https://doi.org/10.3357/AMHP.4848.2017)
- 18↑
Verde P, Trivelloni P, Angelino G, Morgagni F, & Tomao E. E. Neck pain in F-16 vs. typhoon fighter pilots. Aerospace Medicine and Human Performance 2015 86 402–406. (https://doi.org/10.3357/AMHP.4063.2015)
- 19↑
Hu J, Dong Y, Chen X, Liu Y, Ma D, Liu X, Zheng R, Mao X, Chen T, & He W. Prevalence of suicide attempts among Chinese adolescents: a meta-analysis of cross-sectional studies. Comprehensive Psychiatry 2015 61 78–89. (https://doi.org/10.1016/j.comppsych.2015.05.001)
- 20↑
Guo S, Sun Q, Zhao X, Shen L, & Zhen X. Prevalence and risk factors for antibiotic utilization in Chinese children. BMC Pediatrics 2021 21 255. (https://doi.org/10.1186/s12887-021-02706-z)
- 21↑
Smith HJ, Taubman SB, & Clark LL. A burden and prevalence analysis of chronic pain by distinct case definitions among active duty U.S. military service members, 2018. Pain Physician 2020 23 E429–E440.
- 22↑
Hermes EDA, Webb TS, & Wells TS. Aircraft type and other risk factors for spinal disorders: data from 19,673 military cockpit aircrew. Aviation, Space, and Environmental Medicine 2010 81 850–856. (https://doi.org/10.3357/asem.2225.2010)
- 23↑
De Loose V, Burnotte F, Cagnie B, Stevens V, & Van Tiggelen D. Prevalence and risk factors of neck pain in military office workers. Military Medicine 2008 173 474–479. (https://doi.org/10.7205/milmed.173.5.474)
- 24↑
Rintala H, Häkkinen A, Siitonen S, & Kyröläinen H. Relationships between physical fitness, demands of flight duty, and musculoskeletal symptoms among military pilots. Military Medicine 2015 180 1233–1238. (https://doi.org/10.7205/MILMED-D-14-00467)
- 25↑
Monnier A, Larsson H, Djupsjöbacka M, Brodin LÅ, & Äng BO. Musculoskeletal pain and limitations in work ability in Swedish marines: a cross-sectional survey of prevalence and associated factors. BMJ Open 2015 5 e007943. (https://doi.org/10.1136/bmjopen-2015-007943)
- 26↑
Posch M, Schranz A, Lener M, Senn W, Äng BO, Burtscher M, & Ruedl G. Prevalence and potential risk factors of flight-related neck, shoulder and low back pain among helicopter pilots and crewmembers: a questionnaire-based study. BMC Musculoskeletal Disorders 2019 20 44. (https://doi.org/10.1186/s12891-019-2421-7)
- 27↑
Grabara M, & Sadowska-Krępa E. Musculoskeletal disorders and the physical activity of territorial army soldiers during the COVID-19 pandemic. BMC Musculoskeletal Disorders 2021 22 796. (https://doi.org/10.1186/s12891-021-04654-2)
- 28↑
Moon BJ, Choi KH, Yun C, & Ha Y. Cross-sectional study of neck pain and cervical sagittal alignment in air force pilots. Aerospace Medicine and Human Performance 2015 86 445–451. (https://doi.org/10.3357/AMHP.4123.2015)
- 29↑
Tegern M, Aasa U, & Larsson H. Cervico-thoracic pain and associated impairments in air force personnel: a cross-sectional study. BMC Musculoskeletal Disorders 2021 22 441. (https://doi.org/10.1186/s12891-021-04301-w)
- 30↑
Nissen LR, Guldager B, & Gyntelberg F. Musculoskeletal disorders in main battle tank personnel. Military Medicine 2009 174 952–957. (https://doi.org/10.7205/milmed-d-03-5508)
- 31↑
Wagstaff AS, Jahr KI, & Rodskier S. +Gz-induced spinal symptoms in fighter pilots: operational and individual associated factors. Aviation, Space, and Environmental Medicine 2012 83 1092–1096. (https://doi.org/10.3357/asem.3146.2012)
- 32↑
Van den Oord MHA, Sluiter JK, & Frings-Dresen MHW. Differences in physical workload between military helicopter pilots and cabin crew. International Archives of Occupational and Environmental Health 2014 87 381–386. (https://doi.org/10.1007/s00420-013-0876-7)
- 33↑
van den Oord MHAH, De Loose V, Meeuwsen T, Sluiter JK, & Frings-Dresen MHW. Neck pain in military helicopter pilots: prevalence and associated factors. Military Medicine 2010 175 55–60. (https://doi.org/10.7205/milmed-d-09-00038)
- 34↑
Thoolen SJJ, & van den Oord MHAH. Modern air combat developments and their influence on neck and back pain in F-16 pilots. Aerospace Medicine and Human Performance 2015 86 936–941. (https://doi.org/10.3357/AMHP.4303.2015)
- 35↑
De Loose V, Van Den Oord M, Burnotte F, Van Tiggelen D, Stevens V, Cagnie B, Witvrouw E, & Danneels L. Individual, work-, and flight-related issues in F-16 pilots reporting neck pain. Aviation, Space, and Environmental Medicine 2008 79 779–783. (https://doi.org/10.3357/asem.2285.2008)
- 36↑
Hoy DG, Protani M, De R, & Buchbinder R. The epidemiology of neck pain. Best Practice and Research. Clinical Rheumatology 2010 24 783–792. (https://doi.org/10.1016/j.berh.2011.01.019)
- 37↑
Son KM, Cho NH, Lim SH, & Kim HA. Prevalence and risk factor of neck pain in elderly Korean community residents. Journal of Korean Medical Science 2013 28 680–686. (https://doi.org/10.3346/jkms.2013.28.5.680)
- 38↑
Damm H, Jönsson A, Rosengren BE, Jehpsson L, Ohlsson C, Ribom E, Mellström D, & Karlsson MK. Prevalence and morbidity of neck pain: a cross-sectional study of 3000 elderly men. Journal of Orthopaedic Surgery and Research 2023 18 36. (https://doi.org/10.1186/s13018-023-03508-y)
- 39↑
Leclerc A, Niedhammer I, Landre MF, Ozguler A, Etore P, & Pietri-Taleb F. One-year predictive factors for various aspects of neck disorders. Spine 1999 24 1455–1462. (https://doi.org/10.1097/00007632-199907150-00011)
- 40↑
Ang B, Linder J, & Harms-Ringdahl K. Neck strength and myoelectric fatigue in fighter and helicopter pilots with a history of neck pain. Aviation, Space, and Environmental Medicine 2005 76 375–380.
- 41↑
Sovelius R, Oksa J, Rintala H, Huhtala H, & Siitonen S. Neck muscle strain when wearing helmet and NVG during acceleration on a trampoline. Aviation, Space, and Environmental Medicine 2008 79 112–116. (https://doi.org/10.3357/asem.2130.2008)
- 42↑
Cohen SP, & Hooten WM. Advances in the diagnosis and management of neck pain. BMJ 2017 358 j3221. (https://doi.org/10.1136/bmj.j3221)
- 43↑
George SZ, Lentz TA, & Goertz CM. Back and neck pain: in support of routine delivery of non-pharmacologic treatments as a way to improve individual and population health. Translational Research 2021 234 129–140. (https://doi.org/10.1016/j.trsl.2021.04.006)
- 44↑
Blanpied PR, Gross AR, Elliott JM, Devaney LL, Clewley D, Walton DM, Sparks C, & Robertson EK. Neck pain: revision 2017. Journal of Orthopaedic and Sports Physical Therapy 2017 47 A1–A83. (https://doi.org/10.2519/jospt.2017.0302)
- 45↑
Ang BO, Monnier A, & Harms-Ringdahl K. Neck/shoulder exercise for neck pain in air force helicopter pilots: a randomized controlled trial. Spine 2009 34 E544–E551. (https://doi.org/10.1097/BRS.0b013e3181aa6870)
- 46↑
Harrison MF, Coffey B, Albert WJ, & Fischer SL. Night vision goggle-induced neck pain in military helicopter aircrew: a literature review. Aerospace Medicine and Human Performance 2015 86 46–55. (https://doi.org/10.3357/AMHP.4027.2015)
