Is anterior cruciate ligament graft rupture (after successful anterior cruciate ligament reconstruction and return to sports) actually a graft failure or a re-injury?

Purpose: The objective of this study is to discuss the fact that whether graft rupture after successful anterior cruciate ligament (ACL) reconstruction surgery is due to graft failure or re-injury to the reconstructed ACL. Methods: In total, 340 sportspersons, meeting our inclusion criteria, were assessed for rupture of ipsilateral ACL graft and ACL injury of the contralateral knee. Patients with ipsilateral ACL graft rupture were labelled as group 1, while those with contralateral ACL injury were labelled as group 2. Both groups were compared for potential risk factors for ACL injury, and statistical analysis was performed to study whether the graft acted as an additional risk factor. Results: Of the 340 sportspersons, 25 patients suffered a total of 26 injuries. Ipsilateral graft rupture rate was 2.4% (8 of 340) at a mean follow-up of 25.5 +/- 40.57 months, and the contralateral ACL injury rate was 5.3% (18 of 340) at a mean follow-up of 18.11 +/- 19.97 months, with an overall re-injury rate of 7.6%. Both groups were comparable for risk factors for ACL injury: age (p = 0.255), gender (p = 0.534), mode of re-injury (p = 0.523), level of sports activity, type of graft used (p = 0. 918), graft diameter (p = 0.607), duration from injury to index surgery (p = 0.492), duration from index surgery to re-injury (p = 0.638), timing of return to sports after index surgery (p = 0.303), duration of sporting activity before second injury (p = 0.657), and Tegner's level of sports activity (p = 0.486). Conclusion: Because the rate of contralateral ACL injury is higher than the ipsilateral graft rupture and the risk factors for ACL injury are comparable in both groups at a follow-up period, which is suggestive of ligamentization of the graft, we suggest that it might be an ACL re-injury rather than graft failure.