This prospective biomechanical study used motion capture, EMG, and musculoskeletal modeling in 26 male ACLR athletes cleared for RTS and 22 healthy controls. It tested whether single-leg vertical jump metrics detect residual knee dysfunction better than the horizontal hop tests currently used in RTS decision-making.
The hop battery (single-leg hop for distance, triple hop, crossover hop) has been the standard RTS gatekeeper after ACLR for decades, with >90% LSI widely used as the clearance threshold. This paper demonstrates that athletes who clear that threshold still carry a 25-30% knee work deficit — the hop tests simply do not load the knee enough to detect it.
When you are making an RTS decision after ACLR, add single-leg vertical jump height and RSI to the assessment. An LSI below 85-90% on vertical jump height or a large asymmetry in RSI should prompt continued rehabilitation even if the hop battery looks clean.
Pay particular attention to landing mechanics: an athlete who compensates with a stiffer, more extended knee and exaggerated trunk lean may be passing your functional tests while moving in a pattern that raises reinjury risk. What looks like a cleared athlete may be a compensation strategy in disguise.
The authors also highlight soleus as an underappreciated rehabilitation target. Reduced soleus contribution removes an ACL-protective posterior shear force during landing, and targeted soleus strengthening may be warranted before RTS.
This prospective biomechanical study used motion capture, EMG, and musculoskeletal modeling in 26 male ACLR athletes cleared for RTS and 22 healthy controls. It tested whether single-leg vertical jump metrics detect residual knee dysfunction better than the horizontal hop tests currently used in RTS decision-making.
The hop battery (single-leg hop for distance, triple hop, crossover hop) has been the standard RTS gatekeeper after ACLR for decades, with >90% LSI widely used as the clearance threshold. This paper demonstrates that athletes who clear that threshold still carry a 25-30% knee work deficit — the hop tests simply do not load the knee enough to detect it.
When you are making an RTS decision after ACLR, add single-leg vertical jump height and RSI to the assessment. An LSI below 85-90% on vertical jump height or a large asymmetry in RSI should prompt continued rehabilitation even if the hop battery looks clean.
Pay particular attention to landing mechanics: an athlete who compensates with a stiffer, more extended knee and exaggerated trunk lean may be passing your functional tests while moving in a pattern that raises reinjury risk. What looks like a cleared athlete may be a compensation strategy in disguise.
The authors also highlight soleus as an underappreciated rehabilitation target. Reduced soleus contribution removes an ACL-protective posterior shear force during landing, and targeted soleus strengthening may be warranted before RTS.