People Are More Variable Than Their Hop Test Would Suggest: Hop Performance and Self‐Reported Outcomes Over 11 Years Following ACL Reconstruction

Abstract

We aimed to report the trajectory of self‐reported outcomes up to 11 years post‐ACLR. We also explored the relationship between hop performance at 1 year and: (i) future self‐reported knee outcomes; and (ii) risk of subsequent knee events. 124 participants (43 women, mean age 31 ± 8 years) were recruited at 1 year following hamstring‐autograft ACLR. Hop performance was assessed with single‐forward and side‐hop tests. Follow‐up was completed at 3 (n = 114), 5 (n = 89) and 11 years (n = 72) post‐ACLR. Self‐reported outcomes were assessed at each follow‐up with the Knee injury Osteoarthritis Outcome Score (KOOS) pain and quality of life (QOL) subscales. Generalized linear mixed models estimated the relationship between hop performance and self‐reported outcomes. Subsequent knee events (new injury/surgery) to either knee were recorded, with the relationship between hop performance and risk of subsequent knee events analyzed with Cox proportional hazards. Self‐reported knee outcomes were stable (mean change < 10 points) across all timepoints but with major within‐sample variability. There was a modest relationship between greater hop performance at 1 year and better future KOOS‐pain (average marginal effect [AME] % improvement with + 1 cm single forward hop = 0.06% [95% CI 0.02–0.10]). A nonlinear spline relationship showed better single‐forward hop performance was associated with better KOOS‐QOL for scores < 108 cm, not present for higher hop scores > 108 cm. There were 21 index and 11 contralateral subsequent knee events. Hop performance was not related to risk of a subsequent knee event (hazard ratio index knee 0.99 [95% CI 0.98–1.02]). In conclusion, self‐reported knee pain and quality of life were generally stable across the 11‐year follow‐up period. Greater hop performance at 1‐year post‐ACLR was related to better self‐reported knee outcomes up to 11‐year follow‐up (of questionable clinical importance), but not associated with the risk of subsequent knee injury/surgery.