Prior knee injury and risk of future hospitalization and discharge from military service

Background: Athletic capability is paramount for survival in military basic training and successful service. Orthopedic conditions are common reasons for hospitalization and premature discharge of military recruits. Medical f itness for military service is determined through a medical examination. In dividuals medically disqualified may receive a waiver to enter the service on a case-by-case basis. This study was carried out to determine how indivi duals with a medical waiver for knee problems compared to recruits without a history of knee injury regarding hospitalization and military discharge. Methods: Two hundred eighty-one enlisted recruits with a history of a waive r for a knee condition were considered high risk. The comparison group was 843 recruits without prior knee pathology. Comparisons were made using freq uency and chi-square analyses, relative risk estimates, and survival analys es. Individuals in the high-risk group were 1.4 (CI 1.0, 2.1) times more li kely to be hospitalized for any diagnoses and 8.0 (CI 2.1, 29.9) times more likely to be hospitalized for a knee condition than those in the compariso n group. Results: Individuals with a knee waiver were 2.1 (CI 1.3, 3.5) times more l ikely to be prematurely discharged, and 14.0 (CI 4.6, 39.6) times more like ly to be discharged for a knee-related condition than those in the comparis on group. Conclusions: Unfavorable outcomes were more likely in recruits disqualified initially and granted a waiver than in recruits without a history of knee injury. Military service requires intense physical activity; therefore, fur ther research should be conducted to limit knee-related morbidity, especial ly in those with a prior history of knee injury.