Investigating Kinematic and Kinetic Asymmetries During Sit/Stand Movements with a Powered Knee-Ankle Prosthesis: A Pilot Study

Individuals with lower-limb amputation often experience significantly decreased daily activity due to difficulty in completing sitting and standing tasks. Additionally, due to the lack of power provided by their passive prosthetic limb, their movements are typically asymmetric, leading to increased rates of osteoarthritis and lower back pain. A study by Welker et al. introduced a novel data-driven controller implemented on a powered knee-ankle prosthesis to aid individuals with transfemoral amputation in sitting and standing by providing a biologically inspired torque to both the knee and ankle, which saw reductions in ground reaction force loading asymmetries. The purpose of this study is to further investigate asymmetry in kinematics and kinetics when wearing the powered prosthesis with the same novel controller. For our study, two participants performed various sit/stand tasks at three stool heights and two speeds. Using optical motion capture and ground reaction forces to determine inverse kinematics and inverse dynamics revealed significant differences between the intact and prosthesis side hip and knee torques, but still showed reduced asymmetry in kinematics and kinetics compared to previous literature with passive and powered prostheses. These results suggest the controller's potential to alleviate secondary conditions like osteoarthritis by improving these asymmetries.