Ethics number: 57/2018

Background: Stroke is a non-communicable disease, causing global death and disability. People who survive a stroke present with walking impairments, mainly due to the paresis that impairs their ability to bear weight on the affected limb. One of the goals of rehabilitation is to improve the weight bearing so that the affected person can have a functional walking pattern. However, the measurement of weight bearing is a challenge. The gold standard for measuring weight bearing like the force plate is not practical for majority of the clinical settings due to financial restrictions, logistical and technical challenges. This study therefore explored the validity and reliability of the digital scale, when compared to the force plate, to measure lower limb weight bearing.

Methodology: A cross-sectional validation study was conducted with forty stroke patients aged 40-70, who suffered their first stroke resulting in hemiplegia or hemiparesis. Weight distribution on individual lower limbs was measured with the participants standing astride on the two AMTI^® force plates first, followed by the two Pure Pleasure^® digital scales. Three measurements were recorded for each device, two by the researcher and one by the research assistant.

Data Analysis: The inter-rater and intra-rater readings were assessed by determining the intra-class coefficient (ICC) and agreement between the two devices, using the Bland-Altman method.

Results: Excellent intra- and inter-rater reliability with (ICC values 95% confidence intervals 0.96; 0.99 and 0.98; 0.99 respectively) were found. The Bland-Altman plot revealed good agreement between the digital scale and the force plate, with force plate to digital scale ratios of 1.58:1.56 (SD ±0.7).

Conclusion: The measurements obtained with digital scale were valid and in agreement with the force plate measurements, and therefore valid with excellent inter- and intra-rater  reliability demonstrated. Hence, the digital scale could be used confidently by clinicians as an objective cost-effective, user friendly and portable measurement of lower limb weight bearing  in rehabilitation settings

Keywords: weight bearing assessment, lower limb weight bearing, weight bearing following stroke, limb loading, weight bearing using digital scales