Incidence and outcomes of anterior cruciate ligament reconstruction among US Army aviators

Background: The incidence, injury history and aeromedical disposition of an terior cruciate ligament (ACL) reconstruction among Army aviators is unknow n. Methods: The U.S. Army Aviation Epidemiology Data Register was queried f or the study period of calendar years 1988-95. Factors considered included age, gender, type and mechanism of injury, prior history of ACL reconstruct ion, and final aeromedical disposition. The population was divided into two groups: Group I aviators had no history of ACL injury before entering avia tion service, while Group II aviators had ACL reconstructions prior to ente ring aviation service. The data set was analyzed to determine the incidence of ACL reconstruction, to characterize the type and mechanism of injury an d to determine the risk of aeromedical termination from service; Results: T he ACL reconstruction rate (ACL reconstructions/1000 aviators per year) was 0.52 overall, 0.50 for males and 1.39 for females. Sports accounted for 76 % of the injuries requiring ACL reconstruction. The ACL reconstruction rate in Group I was 0.050%, while that of Group II was 63.3%. Among Group I avi ators requiring ACL reconstruction, 94.3% returned to aviation service, 2.3 % were aeromedically terminated and 3.4% were lost to follow-up. Among Grou p II aviators requiring revision ACL reconstruction, 60% returned to aviati on service and 40% were aeromedically terminated. Conclusion: Female aviato rs and Group II aviators had the greatest risk of requiring ACL surgery. Gr oup II aviators had a greater likelihood of undergoing a revision ACL recon struction and subsequent aeromedical termination compared with an initial A CL reconstruction for Group I aviators.