Risk factors for soft tissue knee injuries in active duty U.S. Army Soldiers, 2000-2005

Background: There is a scarcity of analytic research on active duty Army (ADA) knee injuries (KI), such as soft tissue knee injuries (STKI), which are the predominant ADA KI pattern. Purpose: To quantify the independent adjusted association of significant ADA STKI risk factors, 2000-2005. Materials/Methods: Using the Total Army Injury and Health Outcomes Database, we (1) captured absolute STKI numbers and rates (N = 83, 323) and (2) developed regression models to determine significant STKI risk factors. Models included STKI overall and subcategories: meniscus, patella, anterior/posterior cruciate ligament, and medial/lateral cruciate ligament. Results: Eight risk factors significantly increased STKI. They are: (1) prior KI (within 2 years) (odds ratio [OR] 9.83, 95% confidence interval [CI] 9.67-10.00); (2) increasing length of service (OR 1.83, 95% CI 1.76-1.90); (3) increasing age (OR 1.57, 95% CI 1.50-1.65); (4) prior deployment (OR 1.39, 95% CI 1.36-1.41); (5) prior ankle injury (OR 1.16, 95% CI 1.14-1.19); (6) Infantry occupation (OR 1.12, 95% CI 1.04-1.21); (7) marital status (OR 1.10, 95% CI 1.08-1.12); (8) and prior hip injury (OR 1.08, 95% CI 1.03-1.12). Major Conclusion: Soldiers with a prior KI have nearly a 10-fold increased relative risk of developing a subsequent STKI.