Objective To elucidate the relationships between age, return to level I sport (RTS) within the first postoperative year, passing RTS criteria and second anterior cruciate ligament (ACL) injury.
Methods In a prospective cohort study, 213 athletes were followed for 2 years after ACL reconstruction to record second ACL injuries. Independent variables were age, passing RTS criteria and level I RTS within the first postoperative year (vs later or no RTS). We defined passing RTS criteria as ≥90 on the Knee Outcome Survey — Activities of Daily Living Scale, global rating scale of function and quadriceps strength/hop test symmetry.
Results The follow-up rate was >87% for all outcomes. In multivariable analysis, level I RTS within the first postoperative year and passing RTS criteria were highly associated with second ACL injury (level I RTS HR: 6.0 (95% CI: 1.6 to 22.6), pass RTS criteria HR: 0.08 (95% CI: 0.01 to 0.6)), while age was not (age HR: 0.96 (95% CI: 0.89 to 1.04)). Athletes <25 years had higher level I RTS rates in the first postoperative year (60.4%) than older athletes (28.0%). Of those who returned to level I sport in the first postoperative year, 38.1% of younger and 59.1% of older athletes passed RTS criteria.
Conclusion High rates of second ACL injury in young athletes may be driven by a mismatch between RTS rates and functional readiness to RTS. Passing RTS criteria was independently associated with a lower second ACL rate. Allowing more time prior to RTS, and improving rehabilitation and RTS support, may reduce second ACL injury rates in young athletes with ACL reconstruction.
- anterior cruciate ligament
- anterior cruciate ligament reconstruction
- return to sport
- knee function
- knee injury
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Twitter @hegegrindem, @larsengebretsen
Contributors HG proposed the initial idea. All authors contributed to the conception of the work or the acquisition and interpretation of data. All authors critically revised the manuscript and approved the final version. HG, LSM and MAR contributed to the conception of the work. HG, LE, MJA, LSM and MAR contributed to the acquisition and interpretation of data. HG wrote the initial draft. HG, LE, MJA, LSM and MAR critically revised the manuscript and approved the final version. LSM and MAR are the guarantors of the study.
Funding The Delaware-Oslo ACL Cohort Study is supported by grant # R37HD37985 from the US Department of Health and Human Services, National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Competing interests The authors received support from the National Institute of Child Health and Human Development (NICHD; R37HD037985) and National Institute of General Medical Sciences (NIGMS; P30GM103333, U54GM104941) of the National Institutes of Health (NIH). HG and MAR received grants from the NIH during the conduct of the study. MJA received education payments from Arthrex, hospitality payments from Arthrex and Horizon Pharma and honoraria from Horizon Pharma. LE received research and fellowship grants from Arthrex and Smith & Nephew. LSM received grants from the NICHD and NIGMS during the conduct of the study.
Patient consent for publication Not required.
Ethics approval Written informed consent was acquired prior to inclusion and approvals from the Regional Committee for Medical Research Ethics (Oslo) and the Institutional Review Board (University of Delaware) were obtained.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request, given that the transfer does not violate local data protection regulations.