# Validity and reliability of a finger training tool for assessing metacarpal phalangeal joint ranges of motion in asymptomatic participants

## TL;DR

This study tests a new finger training device for measuring joint movement in healthy people, showing it is reliable and closely matches traditional tools.

## Contribution

The study introduces and validates a novel air-guitar system for assessing MCP joint motion with strong reliability and validity.

## Key findings

- The air-guitar system showed strong concordance correlation coefficients (0.62–0.90) with the goniometer.
- Test–retest reliability of the air-guitar system was high (intraclass correlation coefficients 0.82–0.99).
- The air-guitar system's measurements had a mean difference of about 1° from the goniometer, well within acceptable limits.

## Abstract

This pilot study aims to evaluate concurrent validity using the goniometer as a reference tool and test–retest reliability of flexion of metacarpal phalangeal joint (MCP) measurements taken from a finger training device (air-guitar system) in healthy participants. There were ten self -reported asymptomatic participants recruited to test the devices. The measurements of all metacarpophangeal joints of the dominant hands were conducted using a finger goniometer and the air-guitar system. Two measuring sessions were conducted on the same day. The concurrent validity of the air-guitar indicated by strong concordance correlation coefficient (0.62–0.90) with the goniometer and mean difference (approximately 1°) between the two instruments are well below the limit of 5°. The test–retest reliability of MCP measurements from the air-guitar glove (0.82–0.99) was acceptable as a clinically meaningful measurement tool as the intraclass correlation coefficients were higher than 0.7. The standard error of measurement and minimal detectable change of the air-guitar are similar to those of the goniometer. The air-guitar tracking features, when used as a home-based therapy tool, may assist in monitoring change of MCP flexion over a time course with good reliability and strongly associated with the measurements from the goniometer.