A Systematic Review and Meta-Analysis About the Prevalence of Neck Pain in Fast Jet Pilots

Cervical Disc Displacement in Military Pilots

INTRODUCTION

Cervical disc displacement (CDD) may disqualify pilots from flying and have a profound impact on military unit capability. The objective of this retrospective database review is to characterize the incidence and demographic predictors of symptomatic cervical spine disc displacement in pilots of fixed- and rotary-wing aircraft and ground-based controls.

MATERIALS AND METHODS

The Defense Military Epidemiology Database was queried for first-occurrence ICD-9 code 722.0: CDD cases from 2007 to 2015. Injury count rates among aircraft groups and overall incidence per 1,000 person-years were calculated and standardized for age, gender, and military rank, and 95% confidence intervals (CIs) were compared to determine significance.

RESULTS

There were 934 new cases of CDD among active duty U.S. Military pilots during the study period. The overall incidence of CDD in all pilots during this time frame was 2.715 per 1,000 person-years (95% CI, 2.603-2.830). Helicopter pilots had a significantly higher incidence compared to all other aircraft pilots and crew at 3.79 per 1,000 person-years (95% CI, 3.48-4.13). This finding remained statistically significant after standardizing for age, gender, and rank. Among all military officers, increasing age was a risk factor for CDD.

CONCLUSIONS

The U.S. Military helicopter pilots have an increased risk compared to fixed-wing pilots and non-pilot controls. CDD remains a rare, though career-threatening, condition. Increased education and awareness training are warranted for both helicopter pilots and flight physicians to recognize signs and symptoms of cervical pathology. Continued investigations into preventive measures to minimize injury and time unfit for flight are warranted.

Prevalence and risk factors of occupational neck pain in Chinese male fighter pilots: a cross-sectional study based on questionnaire and cervical sagittal alignment

Background

Neck pain (NP) is a common musculoskeletal disorder among fighter pilots and has become a rising concern due to its detrimental impact on military combat effectiveness. The occurrence of NP is influenced by a variety of factors, but less attention has been paid to the association of NP with demographic, occupational, and cervical sagittal characteristics in this group. This study aimed to investigate the prevalence and risk factors of NP in Chinese male fighter pilots using a questionnaire and cervical sagittal measurements.

Methods

Demographic and flight-related data, as well as musculoskeletal pain information, were gathered from Chinese male fighter pilots via a self-report questionnaire. Cervical sagittal parameters were measured and subtypes were classified using standardized lateral cervical radiographs. Differences in various factors between the case and control groups were analyzed using t-tests or chi-square tests. Binary logistic regressions were conducted to explore potential risk factors contributing to NP. Predictors were presented as crude odds ratios (CORs) and adjusted odds ratios (AORs), along with their respective 95% confidence intervals (CIs).

Results

A total of 185 male fighter pilots were included in this cross-sectional study. Among them, 96 (51.9%) reported experiencing NP within the previous 12 months. The multivariate regression analysis revealed that continuous flight training (AOR: 4.695, 95% CI: 2.226-9.901, p < 0.001), shoulder pain (AOR: 11.891, 95% CI: 4.671-30.268, p < 0.001), and low back pain (AOR: 3.452, 95% CI: 1.600-7.446, p = 0.002) were significantly associated with NP.

Conclusion

The high 12-month prevalence of NP among Chinese male fighter pilots confirms the existence of this growing problem. Continuous flight training, shoulder pain, and low back pain have significant negative effects on pilots' neck health. Effective strategies are necessary to establish appropriate training schedules to reduce NP, and a more holistic perspective on musculoskeletal protection is needed. Given that spinal integrated balance and compensatory mechanisms may maintain individuals in a subclinical state, predicting the incidence of NP in fighter pilots based solely on sagittal characteristics in the cervical region may be inadequate.

Neuro-Cardiovascular Responses to Sympathetic Stimulation in Fighter Pilots

INTRODUCTION: The chronic effects of regular exposure to high acceleration levels (G-force) on the neuro-cardiovascular system are unclear. We compared the mean arterial pressure (MAP) and cardiac autonomic modulation between nonpilots (NP) vs. military fighter (FP) and transport (TP) pilots. Additionally, we correlated the cardiac autonomic indices with the cardiorespiratory fitness and flight experience of FP.METHODS: A total of 21 FP, 8 TP, and 20 NP performed a tilt test (TT), during which beat-to-beat blood pressure and heart rate were recorded.RESULTS: No difference was detected between groups for changes in MAP and heart rate variability indices during the TT. However, the analysis of areas under the curves showed a greater increase in MAP in FP vs. TP and NP. Conversely, there was a greater decrease in indices reflecting vagal modulation in TP vs. FP and NP (rMSSD, pNN50, and SDNN), and a greater increase in heart rate and sympathovagal balance in TP vs. other groups (LF/HF). The maximal oxygen uptake was strongly correlated with the vagal reserve in FP (r = -0.74). Moreover, the total flying hours of FP were positively correlated with resting HFnu (r = 0.47) and inversely correlated with resting LFnu (r = -0.55) and LF/HF (r = -0.46).CONCLUSION: FP had a higher pressor response to TT than TP and NP. Vagal withdrawal and sympathovagal increase induced by TT in FP were similar vs. NP and attenuated vs. TP. Greater cardiorespiratory fitness and accumulated flying hours in FP seemed to favor lower sympathetic and greater vagal modulation at rest.dos Santos Rangel MV, de Sá GB, Farinatti P, Borges JP. Neuro-cardiovascular responses to sympathetic stimulation in fighter pilots. Aerosp Med Hum Perform. 2023; 94(10):761-769.

Effects of different helmet-mounted devices on pilot's neck injury under simulated ejection

The helmet plays an important role in protection of pilot's head and enhances the pilot's capabilities and performance significantly with the use of mounted devices such as the Night Vision Goggle (NVG). However, the use of helmet-mounted devices might increase the risk of injury due to the increased helmet weight and change in the centre of gravity of head. In this study, four helmets with different combinations of mounted devices were modelled in a validated human head-neck multi-body model to analyse their effects on the pilot's neck injury during simulated ejection. The probability of neck injury was evaluated and predicted using the N i j neck injury criteria and human injury risk curves, considering the tolerance of injury for upper and lower cervical segment. It was demonstrated that the helmet-mounted devices would increase the compression force and bending moment on cervical spine, especially for the lower cervical segments with higher N i j . In the cases with Night Vision Goggle, N i j of the lower cervical segment reached 0.54, which exceeded the requirement in aviation filed. For the cases with Visor, excessive extension occurred, resulting in a high N i j . The simulation results of this study could provide a reference for helmet and mounted devices design and offer a proposal for the protection of pilots during ejection.

Degenerative cervical spine changes among early career fighter pilots: a 5-year follow-up

INTRODUCTION

Degenerative changes of the cervical spine often cause disability and flight duty limitations among Finnish Air Force (FINAF) fighter pilots. We aimed to study the effect of +Gz exposure on degenerative changes in the cervical spine by comparing cervical MRIs of FINAF fighter pilots and controls.

METHODS

At baseline, the volunteer study population consisted of 56 20-year-old FINAF male fighter pilots (exposure group) and 56 21-year-old Army and Navy cadets (control group). Both groups underwent MRI of the cervical spine at the baseline and after 5 years. Degenerative changes evaluated using MRI included intervertebral disc (IVD) degeneration (Pfirrmann classification), disc herniations, uncovertebral arthrosis, Schmorl's nodes, Modic changes, spinal canal stenosis, kyphosis and scoliosis.

RESULTS

The degree of IVD degeneration in the whole cervical spine increased significantly in both populations with no between-group differences. The prevalence of disc herniations also tended to increase in both populations with no difference in the incidence over the follow-up. However, pilots proved to have more disc herniations at the baseline and at the follow-up. There were virtually no between-group differences in other assessed degenerative changes.

DISCUSSION

We found that IVD degeneration and the prevalence of disc herniations increased at a similar rate for fighter pilots and non-flying military students when all cervical levels were summed up. The lack of difference may be explained by the relatively low cumulative +Gz exposure during the first 5 years of a pilots' career.

Determinants of cervical spine disorders in military pilots: a systematic review

BACKGROUND

Neck pain and cervical spine disorders are widespread among military cockpit aircrew pilots and are often recognized as occupational stressors.

AIMS

This systematic review aimed to identify significant determinants for military pilot neck pain and cervical spine disorders determined through multivariable logistic regression studies.

METHODS

This systematic review was conducted according to the recommendations of the Statement of Systematic Review and Meta-analysis Protocols (Preferred Reporting Items for Systematic Reviews and Meta-Analyses [PRISMA]-P). The following databases were searched for literature: Medline and Embase. We included studies that studied neck pain, cervical spine disorders, and/or radiological abnormalities and associated exposures (adjusted odds ratios, ORadj) in military cockpit aircrew. The trustworthiness, relevance and results of the published papers were evaluated using the Joanna Briggs Institute critical checklist.

RESULTS

A total of three studies quantified the strength of the correlations between exposures and outcomes. Significant determinants/risk factors of neck pain, cervical spine disorders and radiological abnormalities were identified as age (ORadj: 1.092 [95% CI 1.054, 1.132]), fighter type (ORadj: 3.9 [95% CI 1.1, 13.9]) and absolute rotation angle of C2-7 (ARA) (ORadj: 0.91 [CI 0.85, 0.98]). The following variables were unable to demonstrate statistical significance: flying hours, body height and body mass index.

CONCLUSIONS

Military cockpit aircrew's frequent neck pain after a flight raises concerns about cervical spine disorders. Age, fighter type and ARA C2-7 are strong predictors of neck pain and cervical spine disorders. More research is needed on occupational determinants and risk factors for neck pain and cervical spine disorders in military cockpit aircrew.

A Preliminary Analysis of the Costs and Benefits of Physical Therapy and Strength Training for Fighter Pilots

BACKGROUND: Occupational hazards facing high performance aircraft pilots (“fighter” pilots) can cause injury, time lost from flying, and voluntary or involuntary career termination. The high cost of training and retaining fighter pilots has spurred interest in the cost effectiveness of preventative and rehabilitative health solutions.METHODS: We investigated the potential cost effectiveness of a 5-yr, $24.9M U.S. preventative health program using equivalent annual worth (EAW) analysis. The program benefits were assessed with a combination of actual and estimated medical cost data and projected pilot retention improvement rates. Sensitivity analysis of variables such as discount rate, medical cost avoidance, and pilot retention improvement rate was conducted.RESULTS: Annualized costs of approximately $5M U.S. were used as the basis of comparison for annualized benefits. A medical cost database was searched to find expected annual direct medical (outpatient) costs related to injury of roughly $531K U.S. for the pilots covered by the program. Using Centers for Disease Control recommendations, approximately $4.7M U.S. was estimated to be the annual work loss cost. The program would presumably reduce a significant portion of these annual costs, but not all. Assuming various proportions of reduced costs by the program, the EAW was found to be consistently negative. However, when pilot retention improvement is included, EAW is positive using conservative assumptions.DISCUSSION: While outpatient and work loss costs will unlikely be completely covered by preventative health programs in this context, a minor improvement in pilot retention (about 1–3 additional retentions per year) produces a net positive annual benefit.Erneston CG, Fass RD, Ritschel JD, Cox AM. A preliminary analysis of the costs and benefits of physical therapy and strength training for fighter pilots. Aerosp Med Hum Perform. 2022; 93(8):637–642.

Cervico-thoracic pain and associated impairments in air force personnel: a cross-sectional study

BACKGROUND

Pain and impaired function in the cervical region are common in Air Force personnel (AFP), but evidence is limited regarding the thoracic region. This cross-sectional cohort study examined associations between cervico-thoracic pain and physical performance among Swedish AFP and explored possible differences and similarities in test performance between fighter pilots (FP), helicopter pilots (HP) and rear crew (RC).

METHODS

AFP (n = 73) from one airbase performed eight tests of movement control of the spine, active cervical range of motion (ROM) in all six directions and isometric strength and endurance of the cervical flexors and extensors. The association between test performance and cervico-thoracic pain (based on the 'Musculoskeletal screening protocol' questionnaire) were analysed in a multiple binary logistic regression model.

RESULTS

For AFP with cervico-thoracic pain (30%), movement control was impaired in the 'neck flexion test' (OR [95%CI] =3.61 [1.06-12.34]) and the 'forward lean test' (OR [95%CI] =3.43[1.04-11.37]), together with reduced flexion ROM (OR [95%CI] =0.93 [0.87-0.99]). Test performance was in general similar between the three groups, but FP and HP could control the 'forward lean test' to a significantly higher degree than RC (p = 0.000). Further, FP showed significantly greater ROM in lateral flexion to the right compared to HP and RC (mean: 40.3°, 36.2° and 33.4°, respectively, p = 0.000), and they showed higher, although not significant, flexor strength than RC (p = 0.026).

CONCLUSIONS

The impaired function associated with cervico-thoracic pain highlights the need for a deeper understanding of such relationships when designing tools to systematically optimize the physical performance and prevent pain among AFP. Studies with a longitudinal design are warranted to examine any causative associations between pain and impairments.

Exercise Programs Targeting Scapular Kinematics and Stability Are Effective in Decreasing Neck Pain: A Critically Appraised Topic

Clinical Scenerio: Neck pain is a costly symptom in both civilian and military worlds. While traditional treatments include deep neck flexor stabilizing exercises, manual therapy, electrical therapy, and other nonsurgical interventions, scapular orientation and stability training has emerged as a possible tool to reduce neck pain severity. Methods that can be coached at a distance could be of value in virtual appointments or circumstances where access to a qualified manual therapist is limited. Focused Clinical Question: What is the effectiveness of including exercise programs targeting scapular kinematics and stability to decrease neck pain? Summary of Key Findings: Exercise programs targeting scapular kinematics and stability, with coaching and individualized progressions, appear to reduce neck pain severity. Clinical Bottom Line: Evidence supports the inclusion of exercises for scapular kinematics and stability at a prescription of 3 sessions per week, with a duration of 4 or 6 weeks. Exercise programs should include a "learning" or coaching phase to ensure exercises are performed as intended, and exercise progressions should be based on participant ability rather than predetermined timelines. Further research is needed to better understand the benefits of this potential strategy and the statistical impact of scapular-focused exercise interventions on neck pain in specific populations like military and athletes. Strength of Recommendation: There is 'Fair' to 'Good' evidence from 2 level 1b single-blind randomized control studies and 1 level 2b pre-post test control design study supporting the inclusion of exercise programs targeting scapular kinematics and stability to decrease chronic neck pain severity.

Factors associated with neck pain in fighter aircrew: a systematic review and meta-analysis

Neck pain is a common complaint among fighter aircrew, impacting workforce health and operational capability. This systematic review aimed to identify, evaluate and synthesise the current evidence for factors associated with the occurrence of neck pain among fighter aircrew. Six electronic databases were searched in June 2019 and updated in June 2020 utilising the maximum date ranges. Included studies were appraised for methodological quality, ranked according to level of evidence and relevant data extracted. Where methods were homogeneous and data availability allowed, meta-analyses were performed. A total of 20 studies (16 cross sectional, one case-control, one retrospective cohort and two prospective cohort) were eligible for inclusion. Of the 44 factors investigated, consistent evidence was reported for greater occurrence of neck pain among aircrew operating more advanced aircraft and those exposed to more desk/computer work, while another 12 factors reported consistent evidence for no association. Of the 20 factors where meta-analyses could be performed, greater occurrence of neck pain was indicated for aircrew: flying more advanced aircraft, undertaking warm-up stretching and not placing their head against the seat under greater +Gz. Despite many studies investigating factors associated with neck pain among fighter aircrew, methodological limitations limited the ability to identify those factors that are most important to future preventive programmes. High-quality prospective studies with consistent use of definitions are required before we can implement efficient and effective programmes to reduce the prevalence and impact of neck pain in fighter aircrew. PROSPERO registration number: CRD42019128952.Neck pain is a common complaint among fighter aircrew, impacting workforce health and operational capability. This systematic review aimed to identify, evaluate and synthesise the current evidence for factors associated with the occurrence of neck pain among fighter aircrew.

Development of a patient-reported outcome measure for neck pain in military aircrew: qualitative interviews to inform design and content

INTRODUCTION

The prevalence of flight-related neck pain is 70% in UK fast jet pilots; much higher than the general population. The Aircrew Conditioning Programme and direct access physiotherapy exist to minimise the impact on military capability, but a population specific patient-reported outcome measure (PROM) is required to investigate the effectiveness of these. We aimed to explore the experiences of flight-related neck pain to inform the content validity and development of a population specific PROM.

METHODS

Qualitative semistructured interviews combining phenomenological and grounded theory methods, reported using Consolidated criteria for Reporting Qualitative research guidelines. A purposive sample of 10 fast jet pilots with neck pain was recruited. Concept elicitation interviews were audio recorded, transcribed verbatim along with field notes. Data analysis involved subject and methodological expertise used a concept elicitation approach.

RESULTS

Participants included 10 male fast jet pilots, age 34.7 years. Identified themes included: (1) physical symptoms associated with flying activities; (2) occupational effects revealed modifications of flying, or 'suboptimal' performance owing to neck pain; (3) psychological effects revealed feelings or worry and (4) social and activity effects showed impact on out of work time.

CONCLUSION

Population-specific occupational, psychological and social factors should be considered alongside physical symptoms when managing neck pain in military aircrew. Findings support the development of a PROM specifically designed for military aircrew with neck pain.