A cross-sectional study was conducted on patients admitted with stroke as the main diagnosis to the Department of Rehabilitation Medicine, Kyung Hee University Hospital, Gangdong, between November 2020 and November 2021. Inclusion criteria were: (1) adults ≥ 18 years, (2) patients with hemiplegia and within 6 months of stroke onset, (3) those who scored above level 2 out of 5 in a manual muscle test, (4) those with cognitive function sufficient to understand the study, and (5) those who could be evaluated for gait analysis and balance. Exclusion criteria were: (1) age < 18 years, (2) patients with cerebral palsy, traumatic brain injury, and cranial nerve diseases, and (3) patients with severe functional deterioration that would make analyzing gait and evaluating balance difficult.
Functional status was assessed using the Korean version of the Modified Barthel Index (K-MBI) and Short Physical Performance Battery (SPPB).
The K-MBI evaluates a patient's degree of dependence when performing activities of daily living in five categories: fully independent, minimal help required, moderate help required, substantial help required, and inability to perform tasks. The evaluation consists of 10 areas: personal hygiene, bathing, feeding, toileting, stair climbing, dressing, bowel control, bladder control, ambulation, wheelchair or chair/bed transfer; complete dependence is scored as 0 points, and complete independence is scored as 100 points.
The SPPB measures balance, walking speed, and rising from a chair to objectively evaluate the physical function of the elderly. The sense of balance is determined by whether tandem, semi-tandem, and side-by-side stances can be maintained for more than 10 s. Walking speed is determined by the seconds that it takes to walk 4 m, and rising from a chair is assessed by the time it takes to repeat standing and sitting five times. Each evaluation is scored 4 points per item, with a maximum of 12 points.
In addition, as a quantitative strength test, the hand grip strength, and the strength of the extensor and flexor muscles of the knee joint of the hemiplegic and non-hemiplegic sides were measured using a dynamometer. To evaluate flexibility, the sit and reach test was performed, which measures the maximum length that the arm can be extended forward when sitting on the floor with the legs extended.
Balance was assessed using the Berg balance scale (BBS), Trunk Control Test (TCT), and Trunk Impairment Scale (TIS).
BBS is a tool for objectively evaluating static and dynamic balance in various postures. Fourteen items are applied to daily life, such as sitting, standing, and changing posture, with a score of 0 to 4 for each item, and a total score of 0 to 56. The higher the score, the higher the level of balance, and independent walking is expected.
The TCT is a tool used to evaluate the trunk control of stroke patients. It consists of four items: rolling to the weak side, rolling to the strong side, balance in a sitting position, and sitting up from lying down. Each item is scored from 0 to 25, with a higher score indicating better trunk control. The maximum score possible is 100 points.
The TIS includes three subscales: static sitting balance (3 items), dynamic sitting balance (10 items), and coordination (4 items), with a maximum score of 7, 10, and 6, respectively. The total TIS score ranges from 0 to 23, and the higher the score, the better the trunk control.
The quantitative gait parameters of the patients were measured using the Zebris FDM-T Treadmill (Zebris Medical GmbH, Germany). The machine has 5370 miniature pressure sensors under the treadmill belt, allowing it to analyze the pressure distribution under the feet while standing or walking. The participants were instructed to keep their gaze facing the front. After a 1 min warm-up, participants walked on the treadmill at a speed of 1 km/h for 30 seconds (Fig. 1).
The description of each parameter used in the gait analysis is as follows.
Foot rotation [°]: Describes the angle between the longitudinal axis of the foot and the running direction. (Negative value = inward rotation, positive value = outward rotation)
Step width [cm]: Describes the distance between the right and left feet.
Step length [cm]: Describes the distance between the heel contact of one side of the body and heel contact of the contralateral side.
Step time [s]: Describes the phase within a gait cycle between the heel contact of one side of the body and the heel contact of the contralateral side.
Stance phase [%]: Describes the phase of a gait cycle in which the foot is in contact with the ground.
Loading response phase [%]: Describes the phase between the initial ground contact and the contralateral toe off.
Mid-stance phase [%]: Describes the contralateral toe-off phase and transfer of the body's center of gravity over the weight-bearing foot.
Pre-swing phase [%]: Describes the phase during a gait cycle that begins at the contralateral initial contact (when the heel of the contralateral side touches the ground) and ends at toe off of the viewed side of the body.
Swing phase [%]: Describes the phase of a gait cycle during which the foot has no contact with the ground.
A butterfly diagram analyzed the course of the center of pressure (COP) during the selected step cycles. When considering the double-stance phase and load transfer, a typical butterfly diagram of the force application points was produced (Fig. 2).
Gait line length: This parameter is characterized by the position of the center of pressure (COP). Only the ground contacts of one side of the body were considered. The parameter covered the progression of the COP of all the steps recorded of one side of the body.
Single support line: This parameter is the length of the movement of the COP during single-leg support.
Anterior/posterior position: This parameter describes the shift forward or backward of the COP intersection point in chronological sequence, taking all the steps into consideration. The initial or zero position is the rearmost place where the heel contacts the ground.
Lateral symmetry: This parameter describes the left/right shift of the COP intersection point in chronological sequence, considering all the steps. A negative value indicates a shift to the left, and a positive value indicates a shift to the right. The initial or zero position is shown as the central point of the illustration.
Statistical analysis was performed using SPSS 25.0 version for Windows. Because of the high multicollinearity between independent variables, there was a limitation in implementing multivariate linear regression, and the correlation between each evaluation item was analyzed using Spearman correlation analysis. A p-value < 0.05 was considered statistically significant, r = 0.1–0.3 was interpreted as a weak linear relationship, r = 0.3–0.7 as a moderate linear relationship, and r = 0.7 or higher as a strong linear relationship.