Validation of a Device to Accurately Monitor Knee Kinematics during Dynamic Movements

Abstract

The incidence of anterior cruciate ligament (ACL) injury in athletes who play multidirectional sports has increased over recent times. Female athletes are at a higher risk of sustaining the ACL injury when compared to their male counterparts involved in the same sport. Various intrinsic (anatomical and hormonal) and extrinsic (biomechanical) factors have been identified that contribute to the increased risk of injury. Sex differences in the kinematics and kinetics of the lower extremity between males and females have been identified while performing various physical tasks has been a topic of discussion since a long time. While it’s difficult to control the anatomical and hormonal factors, identifying and modifying the biomechanical factors that contribute to the ACL injury is possible. Wearable sensors involving inertial measurement units (IMUs) have been developed to monitor lower extremity motion and help in assistance with rehabilitation. The purpose of this study was to validate a set of wearable IMUs against a 3D motion analysis system to monitor the lower extremity motion during jumps and runs in a laboratory and to determine whether IMUs could be used to estimate ground reaction force at landing. An average difference of 5°-10° for flexion, 4°-6° abduction and internal rotation was reported during jump and run. The results of this study showed that correlation between ground reaction force and tibial acceleration is poor when data from all the subjects were included together. However, the correlation was improved when subjects were examined individually. A strong correlation was observed between the resultant ground reaction force and the resultant tibial acceleration during jumping and running between both the legs for the eight subjects when examined individually.