Test–retest reliability and validity in lower limb proprioception tests using image capture technique in healthy adults

Abstract Background Proprioceptive assessments in clinical practice remain confined to ordinal scales, with a lack of ratio scales. Quantitative proprioception assessments such as threshold to detect passive motion (TDPM) and joint position sense (JPS) help determine the severity of functional impairments and evaluate treatment efficacy. However, their clinical introduction remains challenging due to the extensive and costly equipment required for their measurement. Purpose To investigate the test–retest reliability and validity in the simplified TDPM and JPS using 14 image capture techniques in targeting hip, knee, and ankle joints. Methods This study included 16 volunteers. The measurements were conducted in individual rehabilitation rooms located within the wards of our hospital. Examiners measured a total of 12 TDPM and JPS, including hip, knee, and ankle joints, each performed three times. Moreover, the multi-joint TDPM, distinguished into lower limb flexion and extension patterns, was additionally performed. These measurements were repeated 1 week later. In statistical analysis, the test–retest reliability and construct validity were evaluated using intraclass correlation coefficients (ICC) and Spearman’s rank correlation coefficients. Results The TDPM, multi-joint TDPM, and JPS (variable data; VE) demonstrated moderate reliability across all tested movement directions (TDPM: ICC 0.52–0.70, limits of agreement [LOA] < 10°; multi-joint TDPM: ICC 0.64–0.73, LOA < 10°; JPS: ICC 0.55–0.78, LOA < 10°). No significant correlation was observed between these tests. Conclusions TDPM and JPS using image capture techniques can reliably measure proprioception and serve as independent tests to evaluate different aspects of proprioception. These findings contribute to future studies aimed at introducing quantitative proprioception tests into clinical practice and facilitating clinical decision-making for rehabilitation targeting proprioceptive impairment.