Sit-To-Walk Strategy Classification Using Hip and Knee Joint Angles at Gait Initiation

Abstract

Abstract Sit-to-walk (STW) is categorised by three movement strategies - forward continuation, balance and sit-to-stand-and-walk (SiStW). Literature identified strategies through biomechanical parameters using gold standard laboratory equipment, which is expensive, bulky, and not easily integrated into treatment solutions. As strategy becomes apparent at gait-initiation (GI) and the hip/knee are primary contributors in STW, this study proposes the hip/knee joint angles at GI, as an alternate and standalone method of strategy classification - measurable using wearable sensors. To achieve this, K-means clustering was implemented using three clusters and two feature sets (hip/knee angles); with data from an open access online database (age:21–80 years; n = 10). The results identified forward continuation with the lowest hip/knee extension at GI, followed by balance and then SiStW. From this classification, strategy biomechanics were investigated. The biomechanical parameters (derived in this study) that varied between strategies (P < 0.05) were time, horizontal centre of mass (COM) momentum, braking impulse, centre of pressure (COP) range and velocities, COP-COM separation, hip/knee torque and movement fluency. The derived strategy biomechanics are consistent with literature and validate the classification results. Through strategy classification an individual’s strategy-specific biomechanics can be understood and would aid the design and evaluation of interventions for movement impaired individuals.