Biomechanical analysis of gait initiation in stroke survivors based on a modified phase segmentation method

This study aims to explore the characteristics of gait initiation in stroke patients with hemiplegia across various phases by proposing a refined gait initiation phase segmentation method tailored to this population. Additionally, the study investigates the correlation between gait initiation parameters and clinical assessment scales to evaluate their clinical value in development of functional assessment and rehabilitation strategies.

A total of 34 patients with hemiparetic stroke and 34 age- and sex-matched healthy controls participated in the study. All participants performed gait initiation with each limb three times. Ground reaction force, center of pressure (COP), and kinematic data were recorded using a gait analysis system. The gait initiation process was divided into four phases based on COP trajectory and movement features. Step length, step width, initial paretic limb loading, duration and COP displacement across various phases, and the peak (F _xmax) and impulse (Impulse_x) of the anteroposterior ground reaction force for each limb were calculated. Stroke patients also underwent clinical assessments.

Stroke patients exhibited increased step width and total initiation duration (p < 0.05); reduced step length, single-support time of paretic limb, COP displacement in anteroposterior (DCOPX) and mediolateral (DCOPZ) directions during both the first phase (P1) and single-support phase (P3), paretic limb loading, F _xmax and Impulse_x (p < 0.05). Compared to non-paretic limb initiation, paretic limb initiation showed shorter duration and reduced DCOPZ of the second phase (P2), as well as longer single-support time and total initiation duration (p < 0.05). In addition, the paretic limb generated lower F _xmax and Impulse_x than the non-paretic limb (p < 0.05). DCOPX, F _xmax, and Impulse_x were significantly correlated with clinical assessments to varying degrees (p < 0.05). Overall, greater COP displacement, F _xmax, and Impulse_x were associated with better clinical function, particularly in the paretic limb.

Refined phase segmentation provided additional insight: impaired anticipatory postural adjustment capacity during gait initiation after stroke was reflected by prolonged P2 and reduced COP displacement in P1. Biomechanical parameters of gait initiation may serve as objective indicators of motor function and inform rehabilitation strategies in stroke patients.