Description
CONCLUSION: The results from the Microsoft Kinect™ were found to be in poor agreement with those from a standard motion capture system. Measuring complex lower extremity movements with the Microsoft Kinect™ does not provide adequate enough information to use as an assessment tool for injury risk and return to sport timing.
Summary
This study investigated whether the Microsoft Kinect™, a low-cost, markerless motion capture camera, could accurately measure knee movements associated with ACL injury risk and return-to-sport readiness. Researchers compared the Kinect™ to a gold-standard 3D motion capture system by having 20 healthy participants perform dynamic lower-body exercises, including single-leg hops and box jumps, while both systems simultaneously recorded knee angles. The results showed notable differences between the two systems, with angle measurements differing by roughly 4 to 10 degrees on average and intraclass correlation coefficients ranging from 0.553 to 0.759, indicating only moderate-to-poor agreement. These discrepancies suggest that the Kinect™ cannot reliably capture the precise knee mechanics needed to evaluate ACL injury risk or determine when an athlete is safely ready to return to sport. While affordable motion capture tools are highly desirable in clinical settings, this study highlights that the Microsoft Kinect™ lacks the accuracy required for making these critical assessments.