Examining the Effects of Head Supported Mass on Cervical Spine Biomechanics and Injury Risk in Special Forces Operators
Abstract
Central Problem: Soldiers have displayed an increase in cervical spine problems and musculoskeletal discomfort that is correlated with the increase in weight required by Soldiers to support on their head. This increased weight is primarily due to the implementation of novel Warfighter technologies such as night vision goggles and helmet materials that increase Soldier effectiveness and protect against increasing threats. Previous studies have looked at the role this head supported mass (HSM) plays in injury immediately following high-impact events and performance differences due to muscle fatigue in vibrational scenarios such as helicopter pilots. However, long-term cervical spine injuries that occur due to repetitive stress on the body are being seen in the military at ages younger than the civilian population. The primary goal of this study is to investigate the role of HSM on these long-term consequences, which has not yet been addressed in the research community. This goal will be accomplished through three aims: (1) Survey and compare injury history, neck strength and flexibility, and neck degeneration in three populations: Special Forces Combat Soldiers (SFCS), dismounted Army personnel, and physically active non-military civilians. (2) In a lab setting, obtain muscle activity and head and neck movement while subjects complete a number of relevant military tasks. (3) Use the muscle activity and head/neck movement to inform accurate computer model simulations that will return internal neck stress values to develop long-term repetitive loading neck injury criteria and design guidelines for HSM. Approach and Deliverables: Aim 1 – Neck injury history and neck strength and flexibility tests will be conducted on three cohorts (SFCS, dismounted Army personnel, and physically active non-military) of 171 participants each matched by age and sex to the SFCS cohort. Demographic and medical history data including years of service and number of deployments will be collected for the military cohorts to determine HSM exposure. To compare levels of neck deterioration, a sub-cohort of 30 subjects from the SFCS and physically active non-military cohorts will undergo neck MRI imaging at Duke University. Key deliverables from Aim 1 are evidence that long-term exposure to HSM affects numerous neck injury metrics and suggestions for training and treatment protocols to mitigate the negative effects of HSM. Aim 2 – A sub-cohort of 30 subjects each from the SFCS and physically active non-military cohorts will undergo laboratory testing at Duke University. Participants will conduct a series of military-relevant tasks including a jump landing, running, walking, and looking around corners, both with and without HSM. During each task, neck muscle activity and head/neck movement will be recorded. Head motions from two actions that cannot be replicated in the laboratory (parachute openings and helicopter rides) will be measured in the field at Ft. Bragg using inconspicuous instrumentation that fits comfortably within the ear canal. Key deliverables from Aim 2 are a comparison of the head motions and muscle activity patterns during military-relevant activities with and without HSM. Aim 3 – The head/neck movement and muscle activity determined in Aim 2 will be used to guide the head motion of a computer simulation using a previously validated head/neck computer model. Furthermore, additional data provided by a study conducted by the United States Army Aeromedical Research Laboratory in parallel will provide position time histories for two more unique military-relevant scenarios. The computer model will output internal neck stresses for activities both with and without HSM that can be combined with the HSM exposure and medical history collected in Aim 1 to create a long-term repetitive loading neck injury criterion. A series of simulations sampling the range of HSM possibilities will be coupled with the novel neck injury criterion
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 10, 2021
- Source ID
- W81XWH2020003
Entities
People
- Timothy Sell
Organizations
- Atrium Health
- United States Army