Hop distance to body height ratio outperforms limb symmetry index in predicting second anterior cruciate ligament injury

Abstract Purpose The ability of current return‐to‐sport (RTS) tests to predict second anterior cruciate ligament (ACL) injuries (ACLI) in athletes with a history of ACL reconstruction (ACLR) is unclear. This study aimed to prospectively assess the risk of a second ACLI by identifying the most significant deviation in hop test results in professional athletes after ACLR compared to healthy peers. Methods A total of 30 professional athletes with a history of ACLR and 30 healthy professional athletes participated in this study. Participants performed 10 functional hop tests, and the subsequent limb symmetry index (LSI) was compared between the groups. After a 3‐year follow‐up, the re‐injury rate was assessed among the ACLR group. Fourteen ACLR athletes who sustained a second ACLI were included and matched with 14 controls from the healthy group. The LSI and the hop distance to body height percentage (D/H) were compared between the groups. Results Statistical analyses confirmed a significant decrease in LSI in the ACLR group compared to the healthy group in the triple hop for distance ( p = .023). In re‐injured ACLR athletes, seven different hop tests showed a significant decrease in the D/H index compared to the healthy controls. Meanwhile, for LSI, only the triple cross‐over hop for distance ( p = .045) showed a significant increase in the healthy group. Conclusion Before clearing athletes for RTS, assessing functional hop test results using the hop distance to body height ratio, aligned with normative data from healthy controls, could further enhance the prediction of reduced graft rupture risk. Level of Evidence Level I.