To date, no large population-based studies have focused on permanent occupational disability after injury of the anterior cruciate ligament as far as we know. The purpose of our study was to determine the risk factors for occupational disability after an injury of the anterior cruciate ligament. We identified a cohort of 2192 active-duty personnel in the Army who had been hospitalized between 1989 and 1997 because of an injury of the anterior cruciate ligament and had completed a health risk-assessment survey. With use of the Total Army Injury and Health Outcomes Database, we retrospectively followed these individuals for up to nine years and collected clinical, demographic, occupational, and psychosocial data. These data were then evaluated with bivariate and proportional-hazards regression analyses to identify risk factors for receiving a disability discharge related to an injury of the anterior cruciate ligament. Overall, 209 (9.5%) of 2192 initial anterior cruciate ligament injuries resulted in a permanent disability discharge. In bivariate analyses, the following factors were related to a disability discharge: lower job satisfaction (p < 0.0001), lower education level (p < 0.0001), shorter length of service (p < 0.0001), lower pay grade or rank (p < 0.0001), occupational classification (p < 0.0001), older age (p < 0.01), cigarette-smoking (p = 0.01), and greater mental stress at work (p = 0.02). Associated cartilage injury (p = 0.07) and occupational physical demands (p = 0.08) approached significance; however, with the numbers available, other variables that were hypothesized to contribute to the development of disability, such as gender (p = 0.85), reconstruction of the anterior cruciate ligament (p = 0.52), and other secondary comorbidities of the knee, demonstrated no significant association. Proportional-hazards regression analysis confirmed that pay grade or rank, occupational classification, job satisfaction, age, and length of service were independent predictors of disability discharge. In keeping with risk profiles of several other musculoskeletal disorders, such as low-back pain and carpal tunnel syndrome, the results revealed a multifactorial risk profile in which psychosocial factors were strongly associated with disability discharge from active military duty after injury of the anterior cruciate ligament.
Department of Orthopaedic Surgery, Union Memorial Hospital, 3333 North Calvert Street, Suite 400, Baltimore, MD 21218