Minimal Detectable Change in Muscle Strength Measurements Obtained Using a Hand-Held Dynamometer in Patients with...

Itoh S, Tanikawa H, Kondo H, Ozeki S, Ito T, Fujimura K, Teranishi T. Minimal Detectable Change in Muscle Strength Measurements Obtained Using a Hand-Held Dynamometer in Patients with Stroke. Jpn J Compr Rehabil Sci 2025; 16: 9-18.

The current study aimed to evaluate the reliability of muscle strength measurements using a hand-held dynamometer (HHD) in patients with chronic stroke. Further, it examined the minimal detectable change (MDC₉₅).

Patients who presented with chronic stroke hemiplegia for > 180 days post-stroke onset were analyzed. Muscle strength in the paretic lower limb was assessed using an HHD, and gait speed was evaluated.

For hip flexion, hip adduction, hip abduction, knee extension, ankle dorsiflexion, and ankle plantarflexion, the intra-rater reliability of the muscle strength measurements, as assessed using the intraclass correlation coefficient (ICC), ranged from 0.989 to 0.998. The inter-rater reliability, as assessed using ICC, ranged from 0.886 to 0.939. Bland-Altman analysis did not indicate systematic errors, and the MDC₉₅ of each joint movement was calculated. Muscle strength in hip flexion, hip adduction, knee extension, ankle dorsiflexion, and ankle plantarflexion were significantly associated with gait speed, but not with hip abduction strength. The MDC₉₅ of each muscle strength measurement was established, thereby providing a criterion for detecting actual changes that exceed the measurement error.

The HHD had a high reliability in measuring lower limb muscle strength in patients with chronic stroke hemiplegia. Moreover, an association was found between individual muscle strength and gait ability. Based on this study, specific target muscles for interventions that aim to improve gait speed can be identified. Further, the use of MDC₉₅ allows for a more accurate assessment of the intervention effects.