Uninjured Youth Athlete Performance on Single-Leg Hop Testing: How Many Can Achieve Recommended Return-to-Sport Criterion?

Abstract

Current anterior cruciate ligament reconstruction (ACLR) guidelines utilize single-leg hop tests (SLHTs) to assist in return-to-sport decision making. A limb symmetry index (LSI) of ≥90% is often required; however, after ACLR, most youth athletes cannot achieve this standard. Reporting the performance of age-matched normative controls will allow clinicians to compare post-ACLR performance with noninjured peers, improving the utility of SLHTs. The purpose of this study was to report hop test LSI within healthy youth athletes and determine whether athlete performance surpasses post-ACLR requirements. The LSI for the majority of healthy youth athletes will be ≥90%. Cross-sectional cohort study. Level 3. Each participant performed a single hop (SH), triple hop (TrH), crossover hop (CrH), and timed hop (TiH). A 3-trial mean was utilized to calculate an LSI (nondominant/dominant leg [self-reported kicking leg]) for each hop. The frequency of pass/fail at ≥90% LSI was calculated. Pearson correlation coefficients analyzed the relationship between the different hops, and a 2-way analysis of variance determined the effects of age and sex on LSI. A total of 340 participants (54% male; mean age, 10.9 ± 1.5 years; range, 8-14 years) were included. The mean LSI was >95% for each SLHT (SH, 97.9% [SD, 0.7]; TrH, 96.6% [SD, 0.6]; CrH, 96.8% [SD, 0.8]; TiH, 96.5% [SD, 0.6]). When analyzed as a test battery, only 45% of participants achieved this standard. Significantly weak to moderate correlations existed among hop tests (P < 0.01; r = 0.342-0.520). Age and sex had no effect on LSI (P < 0.05). While the mean LSI in our sample was >95% for each individual hop test, participant performance across all SLHT components varied, such that less than half of healthy athletes could achieve ≥90% LSI across all hops. Current guidelines require ≥90% LSI on SLHTs. The majority of healthy youth athletes could not achieve this standard, which questions the validity of this LSI threshold in youth athletes after ACLR.