Identify the Alteration of Balance Control and Risk of Falling in Stroke Survivors During Obstacle Crossing Based on Kinematic Analysis

Abstract

This study aims to compare the differences in the kinematic characteristics of crossing obstacles of different heights between stroke survivors and age-matched healthy controls and to identify the changes of balance control strategy and risk of falling. Twelve stroke survivors and twelve aged-matched healthy controls were recruited. A three-dimensional motion analysis system and two force plates were used to measure the kinematic and kinetic data during crossing obstacles with heights of 10, 20, and 30% leg length. The results showed that during leading and trailing limb clearance, (AP) center of mass (COM) velocities of the stroke group were smaller than those of the healthy controls for all heights. The decreased distances between COM and center of pressure (COP) in the AP direction during the both trailing and leading limb support period were also found between stroke survivors and healthy controls for all heights. The COM velocity and COM-COP distance significantly correlated with the lower limb muscle strength. In addition, stroke survivors showed greater lateral pelvic tilt, greater hip abduction, and larger peak velocity in the medio-lateral (ML) direction. There was a positive correlation between the COM-COP distance in the AP direction and the clinical scales. These results might identify that the stroke survivors used a conservative strategy to negotiate the obstacles and control balance due to a lack of muscle strength. However, the abnormal patterns during obstacle crossing might increase the risk of falling. The findings could be used to design specific rehabilitation training programs to enhance body stability, reduce energy cost, and improve motion efficiency.

Keywords: balance control; gait; kinematics; obstacle crossing; stroke.

Figures

Figure 1

(A) The sketch map of the gait cycle of obstacle crossing, including Trailing limb supporting period (TLP) and leading limb supporting period (LLP). TOD (the horizontal distance between the trailing toe (trailing limb is in contact with the floor) and the obstacle before crossing the obstacle), TOC (the vertical distance between the toe of leading toe and obstacle when the toe is over the obstacle) as well as HOD (the horizontal distance between the leading heel (leading limb is in contact with the floor at this time) and the obstacle after crossing the obstacle) were also demonstrated. (B) The sketch map of the COM-COP distance at anterior–posterior (AP) and medio-lateral (ML) direction.

Figure 2

Typical trials of the kinematic behavior of the pelvis at (A) Anterior-Posterior (AP) direction, (B) Medio-Literal (ML) direction and (C) Rotation, and hip joint of (D) Flexion/Extension, (E) Abduction/Adduction, (F) Rotation, as well as (G) knee joint Flexion/Extension of the trailing and the leading limb in a patient (female, age 63) and a healthy subject (female, age 62) during the crossing stride sub-phases. See Supplementary Material for all the data trials of stroke and healthy subjects.

Figure 3

The balance measurements in the AP direction (Mean and SD). (A) The velocity at the leading limb clearance. (B) The velocity at the trailing limb clearance. (C) The COM-COP distance during TLP. (D) COM-COP distance during LLP. *Reflects the significant difference between groups, #Reflects the significant difference between heights. The error bar represents 1 SD.

Figure 4

The balance measurements in the ML direction (Mean and SD). (A) The velocity at the peak 1. (B) The velocity at the peak 2. (C) The velocity at the peak 3. (D) COM-COP distance during TLP. (E) COM-COP distance during LLP. *Reflects the significant difference between groups, #reflects the significant difference between heights. The error bar represents 1 SD.

Figure 5

The correlation between the clinical scales and the distance between COM-COP in the AP direction of different periods when crossing the 10% leg length height obstacle. (A) The correlation between the BBS scores and the distance of COM-COP during TLP. (B) The correlation between the BBS scores and the distance of COM-COP during LLP. (C) The correlation between the FMA scores and the distance of COM-COP during TLP. (D) The correlation between the FMA scores and the distance of COM-COP during LLP.