Occupational Exposure to Whole Body Vibration Among U.S. Military Veterans: Acute and Chronic Contributions to Musculoskeletal Disorders and Spine-Area Pain

Significance to VA: There is a lack of prospective longitudinal studies investigating the relationship between risk factors to Veterans and development and progression of musculoskeletal (MSK) spine injury and pain. Military operational exposure to whole body vibration (WBV) is known to contribute to MSK disorders and pain. Our preliminary studies identified accelerated lumbar and cervical spine degenerative changes in military fighter pilots and helicopter aircrew compared to age- and sex-matched civilian controls. Those changes were likely associated with WBV that military aircrew experience during flight training, primarily affected intervertebral discs (IVDs) and endplates, were associated with neck and back pain symptoms and reduced functional capacity, and are likely to lead to lifelong spine-related issues. Therefore, these aircrew, and other military personnel that experience occupational WBV, are likely to enter the VA Healthcare system with pre-existing degenerative changes and spine-related pain symptoms that can progress over time. Similarly, many Veterans enter civilian occupations that involve WBV such as truck drivers and heavy equipment operators that may also have detrimental effects to the spine and lead to spine-related pain. Development of informed interventions and treatment protocols requires a mechanistic understanding of how the spine is acutely and chronically affected by occupational WBV from both structural and physiological perspectives. Innovation and Impact: Novel multi-parametric application of noninvasive magnetic resonance imaging (MRI) techniques such as arterial spin labeling (ASL), T2\* decay from ultra short TE, and diffusion MRI can provide early objective indications of endplate degenerative state and IVD hydration and perfusion, and novel application of upright MR imaging allows for gravitational loading of the IVD while observing segmental and region IVD fluid distribution and transport patterns. Specific Aims: The goal of the proposed effort is to characterize the effects of previous military and current civilian occupational WBV on IVD and endplate health and degeneration (Aim 1), and segmental and regional IVD fluid distribution and transport differences (Aim 2). The endplates contain vasculature that permits IVD fluid exchange and may be linked to IVD fluid dynamics. We propose looking for connections between segmental and regional IVD fluid dynamics, degenerative state of the associated endplates, and WBV exposure (acute-controlled and longitudinal-occupational). Finally, we propose evaluating the impact of body hydration state on IVD fluid distribution and transport following acute (30 min) controlled WBV (Aim 3). Cumulatively, these results inform population-specific preventative measures to preserve endplate health for Veterans in occupations that present with WBV and identify potential areas for further research and targeted treatment of MSK disorders and MSK pain. Methodology: This study will explore acute and chronic changes to the structure and physiology of the spine by enrolling Veterans with prior military or current civilian occupation that involves daily WBV. Advanced MRI sequences will identify endplate sclerosis and physiological changes including disc hydration and perfusion. Acute effects of WBV will be assessed using pre/post MRI scans with experimental WBV. Path to translation/Implementation: Our existing relationships with VA clinicians, including spine surgeons, physical medicine and rehabilitation, and pain medicine, will ensure VA patient applicability of these findings and will help to translate any outcomes from this research and future studies directly into patient care.