丹 洸貴

PURPOSE: Adjusting the tilt and recline angles of a wheelchair is recommended as one of the approaches for preventing pressure injuries associated with mechanical loading in wheelchair users. However, maintaining a fixed inclination may increase pressure on other body areas, raising concerns about the time-dependent risk of ulcers. To address this issue, we proposed an electrically powered wheelchair equipped with a mechanism that continuously changes the tilt angle, similar to the motion of a rocking chair, and developed a prototype as a proof of concept. This cross‑sectional study aimed to evaluate the effectiveness of the prototype wheelchair in reducing and redistributing interface pressure. MATERIALS AND METHODS: Eight healthy participants were enrolled in this study. The electrically controlled tilt angle was programmed to cycle from 0° to 30° in 50 s. Reclining angles were set at 0°, 10°, 20°, and 30°. The pressure at the head, back, and buttocks was recorded. RESULTS: The peak pressure in these areas changed dynamically with tilt variation; increasing the tilt angle raised the peak pressure at the head and back while reducing it at the buttocks. Increasing the reclining angle amplified these changes in the head and buttocks but had no effect on the back. CONCLUSION: Our findings suggest that continuous tilt variation may reduce prolonged exposure to excessive pressure, potentially reducing the risk of ulcers in the buttocks associated with mechanical loading in wheelchair users.

BACKGROUND: Gait-a frequently performed activity of daily living-is thought to reflect multiple dimensions of an individual's physical and cognitive status. Individuals with frailty or mild cognitive impairment (MCI) show decreased gait speed. However, previous studies have not simultaneously considered both statuses, although they frequently co-occur and may act as confounders. The direct association between frailty and gait is well-understood. In contrast, the association between cognitive decline-independent of physical function-and decreased gait speed, as well as the relationship among these three factors (frailty, cognitive decline, and gait speed), is not fully understood. METHODS: This study examined the effect of MCI on gait speed after accounting for frailty. Older individuals were categorized as (1) frailty with MCI, (2) frailty without MCI, (3) pre-frailty with MCI, (4) pre-frailty without MCI, (5) non-frailty with MCI, and (6) non-frailty without MCI. Frailty was assessed using the Kihon checklist and MCI using the Montreal Cognitive Assessment. Participants completed a 10-m walk test under two conditions: comfortable walking and fast walking. Two types of analyses were conducted: mediation analysis and two-way analysis of covariance (ANCOVA). RESULTS: Mediation analysis supported independent relationships between frailty and MCI status and gait speed, suggesting a direct association between MCI and gait speed, even when accounting for frailty. In addition, two-way analysis of covariance indicated significant main effects of both frailty and MCI on gait speed, with no significant interaction between them under the two walking conditions. CONCLUSIONS: These findings suggest that the observed association between MCI and gait speed is largely independent from frailty status, providing additional evidence supporting the association between cognitive function and gait performance.

This study aimed to investigate the timing of foot-off and initial contact at the end of the first walking training session with a Wearable Power-Assist Locomotor (WPAL) in novice healthy users. Eight healthy volunteers with no walking experience with the WPAL participated in this study. The participants walked back and forth on a straight 5 m path for 60 min with the WPAL. We calculated the differences between the participant’s foot-off and initial contact timing, as well as the start and end timing of the pre-programmed WPAL lower-limb swing time. Data were divided into four segments of 100 data points. We calculated the median of the last 100 data points and examined whether it falls within an appropriate time range. The foot-off timing tended to be within the appropriate time range (median, −0.44 s); however, the initial contact timing was earlier than the appropriate time range (median, −0.17 s). Although some participants performed foot-off within the appropriate time range, all performed initial contact earlier than the appropriate time range. These findings may contribute to establishing practice protocols for stable walking with wearable robotic exoskeletons in patients with spinal cord injury.