Anterior cruciate ligament reconstruction (ACLR) has a consistency problem. Athletes get stronger. They pass return-to-sport tests. They look ready.
And still — too many tear the ligament again.
A new study in Medicine & Science in Sports & Exercise suggests part of the issue may not be strength at all, but something harder to see: how consistently athletes move when they land.
Measuring Movement Consistency
Researchers analyzed single-leg landing mechanics in young athletes after ACLR, comparing three groups: uninjured controls, patients who did not sustain a second ACL injury and those who did.
Using motion capture, they evaluated coordination variability — essentially how joints work together during landing — at the time athletes were cleared to return to sport. They then tracked second ACL injuries over the following two years.
Greater Variability, Higher Reinjury Risk
The difference wasn’t subtle. Healthy controls demonstrated the most consistent movement patterns — the lowest coordination variability — on both limbs.
Athletes after ACLR showed greater variability across the board.
And those who went on to sustain a second ACL injury showed the highest variability of all, particularly on the involved limb.
Even the “uninvolved” limb told a story. It, too, showed more variability in ACLR patients compared to controls.
Strength and Symmetry Don’t Tell the Whole Story
For years, return-to-sport decisions have centered on strength, symmetry and performance tests.
This study points to something those measures may miss.
Two athletes can produce the same force, pass the same hop tests and still move very differently. One lands the same way every time. The other does not.
That inconsistency — subtle, difficult to detect in the clinic — may be where reinjury risk lives.
Not Just a Knee Problem
Perhaps the most interesting finding is that this isn’t isolated to the surgical limb.
Elevated variability on the contralateral side suggests a broader neuromuscular control issue — not just a repaired ligament, but a system that hasn’t fully recalibrated.
Consistency May Be the Next Frontier in ACL Rehab
ACLR has long been about restoring stability. But stability isn’t just structural. It’s repeatable.
This study adds to a growing body of evidence that returning athletes to sport may require more than restoring strength and symmetry. It may require restoring consistency — the ability to execute the same movement pattern, over and over, under load.
Because in high-speed sport, it’s not just how well you land. It’s whether you land the same way every time.
Origin Study Title Link: Single-leg Landing Coordination Variability and Second Injury in Young Athletes after Primary Anterior Cruciate Ligament Reconstruction
Authors: Perry, Jennifer A.; Kronenberg, Jamie M.; Thomas, Staci M.; Paterno, Mark V.; Siston, Robert A.; Schmitt, Laura C.