Hop Tests After ACL Reconstruction — Not Enough to Predict Reinjury

Hop tests after anterior cruciate ligament reconstruction can help describe functional readiness, but they should not be used on their own to decide whether an athlete is ready for a safe return to sport. A meta-analysis of 43 studies involving 17,350 participants found only modest associations between selected hop-test results and actual return to sport, with limited value for predicting reinjury.

Why is this study important?

Single-leg hop tests and the limb symmetry index (LSI) are widely used after ACL reconstruction. LSI expresses performance of the operated limb as a percentage of the opposite limb, and a threshold of 90% is often treated as an important marker of readiness. The problem is that symmetry does not necessarily mean full recovery: both limbs may be deconditioned, while jump distance alone says little about landing quality, fatigue, deceleration or performance in an unpredictable sporting situation.

The meta-analysis, published on 1 September 2026 in the Journal of Sports Science and Medicine, examined whether hop-test performance is actually associated with return to sport and subsequent ACL injury.

Question and methodology

The authors searched PubMed, MEDLINE, SPORTDiscus and Web of Science. Eligible studies included patients after primary unilateral ACL reconstruction who had undergone hop testing and for whom return-to-sport or reinjury outcomes were reported. Risk of bias was assessed with a modified Newcastle–Ottawa Scale and certainty of evidence with a modified GRADE approach.

Forty-three studies with 17,350 participants were included. Twenty-four analysed return to sport and 21 analysed reinjury; some studies reported both outcomes.

Key findings

• Achieving an LSI of at least 90% on the single-leg hop for distance was associated with a slightly greater likelihood of return to sport: OR 1.20; 95% CI 1.09–1.33.
• For the triple crossover hop, the association with return to sport was similarly modest: OR 1.18; 95% CI 1.02–1.36.
• For the triple hop for distance, an LSI of at least 90% was paradoxically associated with a slightly higher odds of reinjury: OR 1.05; 95% CI 1.01–1.09.
• The association between the single-leg hop and return to sport was stronger in studies in which more than 90% of reconstructions used hamstring-tendon grafts and in patients without meniscal injury.
• The overall certainty of evidence was rated as low.

Clinical interpretation for an orthopaedic surgeon

The main message is not that a 90% threshold has been validated as a universal cut-off, but that its limitations are substantial. Patients with good symmetry on selected hop tests were somewhat more likely to return to sport, but the effect was small. Returning to activity is also not the same as returning safely: the decision is influenced by the athlete’s goals, sport demands, access to training and advice from the treating team.

The apparently paradoxical association between a good triple-hop result and slightly greater reinjury odds does not show that better-performing patients are rehabilitated poorly. A more plausible explanation is that those who perform better are more likely to return to sporting exposure, creating more opportunities for another injury. These observational associations cannot establish causation.

Limitations

• Studies differed in the timing of testing, definitions of return to sport, activity levels and methods used to define reinjury.
• LSI compares the operated limb with the opposite leg, which may itself have become weaker after months of reduced activity.
• Hop distance does not describe lower-limb alignment, trunk control, deceleration quality or performance under fatigue.
• The analyses cannot separate physical readiness from the amount of subsequent exposure to training and competition.
• Low certainty of evidence limits the ability to define a universal decision threshold.

What could this change in practice?

Hop tests remain useful, but they should form part of a broader return-to-sport assessment that includes strength, movement and landing quality, fatigue tolerance, stability, psychological readiness, time from surgery and the demands of the specific sport. It is also useful to examine the absolute performance of both limbs rather than symmetry alone.

The study does not show that hop tests are unnecessary. It shows that passing a single threshold is not an insurance policy against reinjury and should not automatically trigger unrestricted training.

Related resources

Full rehabilitation protocol after primary, isolated ACL reconstruction →

For broader clinical evidence appraisal and rehabilitation decision-making, see Research Updates, Literature and Evidence-Based Medicine.

Source

Liu Y, Sun Y, Cao M et al. Hop Test Performance is Associated with Return-to-Sport but Shows Limited Association with Reinjury after Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-Analysis. J Sports Sci Med. 2026;25(3):772–806. Published 1 September 2026. PMID: 42713242. DOI: 10.52082/jssm.2026.772. PubMed. Full text.

Polish version

Content prepared by: Tomasz Poboży - orthopaedic surgeon.