B. Schram1,2, E. Canetti1,2, R. Orr1,2, R. Pope3,2
1Bond University, Physiotherapy, Robina, Australia, 2Bond University, Tactical Research Unit, Robina, Australia, 3Charles Sturt University, Physiotherapy, Wagga Wagga, Australia

Background: Osteoarthritis (OA) is the most common condition which affects the joints, with rates in the military of lower limb OA, particularly, increasing over time. Issues arising from OA are one of the most common causes for discharge from the military, with the OA incidence rate in the United States Army reported to be 9.7/1000 person-years. Risk factors for OA include age, female gender, being overweight, previous injury and exposure to occupational tasks, such as heavy lifting, carrying, squatting, kneeling, and crawling.

Purpose: The purpose of this study was to determine the exposures to risk factors for development of lower limb OA during 18-month Army officer training. These were then compared to published minimum threshold exposures for such factors which must exist to establish a reasonably likely causal connection between development of lower limb OA and military service.

Methods: A desktop analysis of the training program was conducted, validated by both direct observations and surveys, and enabling construction of a Job Exposure Matrix (JEM). This analysis was designed to capture the magnitudes of exposures to specific activities, body positions, lifting and carrying tasks, and stair-climbing tasks known to be associated with increased risk of OA development. The method involved a minute by minute analysis of activities conducted during each training day, allowing the estimation of actual and projected cumulative exposures. Minimum threshold exposures identified in the Australian Repatriation Medical Authority’s (RMA) Statements of Principles for increasing risk of lower limb OA were: 1) cumulative lifting or carrying of loads ≥ 20kg totaling 100,000kg or 3,800 hours, respectively, over a 10 year period; 2) at least 366 days of climbing ≥150 stairs per day within a 2 year period; and 3) at least 183 days of kneeling or squatting for a cumulative total of 1 hour per day within a 1 year period.

Results: According to the JEM, officer cadets would likely reach the RMA threshold for carrying loads ≥20kg after approximately four years and 37 weeks of service, and would likely reach the thresholds involving lifting loads ≥20kg and kneeling/squatting after one year of service. The threshold for stair-climbing was unlikely to be reached.  

Conclusion(s): Training and employment as an Army officer exposes personnel to lifting and carrying of loads and kneeling/squatting tasks that are cumulatively likely to reach threshold levels associated with increased risk of developing lower limb OA within five years.

Implications: Lifting and carrying loads and kneeling and squatting postures are important to occupational tasks of army personnel but may increase risk of OA. Ways to reduce cumulative exposures should be developed to reduce risk of lower limb OA.

Funding, acknowledgements: This project was funding by a grant from the Department of Veterans' Affairs

Keywords: defence, tactical, soldier

Topic: Occupational health & ergonomics

Did this work require ethics approval? Yes
Institution: Bond University
Committee: Bond University Human Research Ethics Committee
Ethics number: RP02290

All authors, affiliations and abstracts have been published as submitted.

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