Reliability and validity of the measurement of interdigital muscle thickness using a caliper gauge.
Hajime Tomita, Yumiko Shimizu, Jumpei Kawakami and 3 others
PMID 40757019WHAT IT FOUND
A simple caliper measure of thumb web muscle thickness was consistent when the same examiner repeated it and related to ultrasound, but less consistent between examiners.
It was tested in 41 healthy young adults, not older patients.
Key findings
01The same examiner's repeated measurements were very consistent, with values of 0.948 during relaxation and 0.900 during contraction.
02Different examiners were less consistent, with values of 0.809 during relaxation and 0.690 during contraction.
03IDMT was associated with grip strength, pinch strength, and ultrasound muscle thickness, with values of 0.372 and 0.482 for grip, 0.230 and 0.388 for lateral pinch, 0.348 and 0.409 for tip pinch, and 0.498 and 0.405 for ultrasound.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The study was done in 41 healthy young adults aged 18 to 30 years, not in older adults or patients with hand problems. It did not test whether interdigital muscle thickness relates to daily occupations, activities of daily living, instrumental activities of daily living, frailty, sarcopenia, or clinical outcomes. Agreement between different examiners was 0.809 during relaxation and 0.690 during contraction, so the measurement may vary by examiner. The method used a digital caliper and adhesive stickers, so it has not yet been simplified for routine clinical use. All participants were Japanese students, so the results may not apply to other populations.
Declared interests
The authors declared no conflicts of interest. The work was supported by JSPS KAKENHI Grant Number 23k10222.
The easy way to misread this
Do not read this paper as evidence that caliper interdigital muscle thickness can diagnose hand intrinsic muscle atrophy or guide treatment in older adults. It was tested only in healthy young adults, and it did not show a relationship with daily occupations or functional decline.