Video Analysis of 26 Cases of Second ACL Injury Events in Collegiate and Professional Athletes.
Manuela Vargas, Grace K Chaney, María C Mejía Jaramillo and 3 others
PMID 36793574WHAT IT FOUND
Video analysis of 26 non-contact second ACL injuries showed knee valgus collapse in 18 cases.
Injuries occurred mostly during single-leg landing or cutting, with athletes focused on the ball or opponent. Hip angles remained unchanged, suggesting a stiff landing contributed to the injury.
Key findings
01Knee valgus collapse was observed in 18 of the 26 analyzed injury videos, while hip angles showed no significant changes over time.
02Single-leg landing and cutting or pivoting movements accounted for all observed secondary injuries, with no double-leg landings recorded.
03Athletes were most often externally focused on the ball or an opponent rather than their own landing mechanics at the time of injury.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The sample size was very small, with only 26 usable videos out of 78 found, and the footage is not representative of all second ACL injuries. The study relied on 2D video analysis from broadcast cameras that were not aligned with the athletes, which can distort joint angle measurements. Researchers could not measure ground reaction forces or account for forces traveling through the kinetic chain. The athletes' injury histories, rehabilitation timelines, and time to return to sport were unknown. Protective equipment and clothing obscured exact anatomical landmarks, making joint angle identification imprecise.
The easy way to misread this
Do not assume these specific kinematic patterns caused the injuries or that they apply to all athletes. The study only describes what was visible in a small sample of videos at the moment of injury, and the lack of significant differences between the graft rupture and contralateral tear groups means these findings do not identify a unique mechanism for either type of second injury.