Survival Comparison of Allograft and Autograft Anterior Cruciate Ligament Reconstruction at the United States Military Academy

Abstract

Background: There is recent evidence that use of allograft tendons for anterior cruciate ligament (ACL) reconstruction in young patients may result in increased failure rates compared with autologous grafts.Hypothesis: Allograft ACL reconstruction will result in higher failure rates in young athletes compared with autograft reconstruction.Study Design: Cohort study; Level of evidence, 2.Methods: A prospective cohort study of cadets at the United States Military Academy (USMA) was performed to assess performance of ACL reconstructions performed before entrance to service. Members of the classes of 2007 through 2013 who had undergone prior ACL reconstruction were identified through the Department of Defense Medical Evaluation Review Board reporting and waiver process and evaluated on the first day of matriculation. These participants were followed during their tenure at the academy with revision ACL reconstruction as the primary outcome measure of interest. Kaplan-Meier survival analysis was performed for all graft types using STATA with significance set as P < .05.Results: A total of 120 cadets underwent 122 ACL reconstructions (2 bilateral) before matriculation and compose the prospective cohort. This cohort included 30 female and 90 male cadets. Of these 122 knees with prior ACL reconstructions, the grafts used were 61 bone–patellar tendon–bone (BTB), 45 hamstring, and 16 allograft. A total of 20 failures occurred among this cohort at an average of 545 days from matriculation. Of the failures requiring revision, 7 were BTB (11% of all BTB), 7 were allograft (44% of all allograft), and 6 were hamstring (13% of all hamstring). There was no significant difference in the graft failure between the BTB and hamstring autograft groups. In contrast, those who entered the USMA with an allograft were 7.7 times more likely to experience a subsequent graft failure during the follow-up period when compared with the BTB autograft group (hazard ratio = 7.74; 95% confidence interval [CI], 2.67-22.38; P < .001). When allografts were compared with all autografts combined, a similar increase failure was noted in the allograft group (hazard ratio = 6.71; 95% CI, 2.64-17.06; P < .001).Conclusion: In this young active cohort, individuals having undergone an allograft ACL reconstruction were significantly more likely to experience clinical failure requiring revision reconstruction compared with those who underwent autologous graft reconstruction. The authors recommend the use of autograft in ACL reconstruction in young athletes.