# Criterion Validity and Inter-Method Reliability of a Smartphone Sensor-Based Application for Lower-Limb Range of Motion: In-Person vs. Tele-Assessment

## TL;DR

The PhysioMaster app is reliable for remote tracking of lower-limb joint movement, especially for the ankle, but less accurate compared to in-person tools for hip and knee.

## Contribution

Demonstrates the reliability of a smartphone app for remote joint range of motion assessments despite limited validity for some joints.

## Key findings

- Ankle plantarflexion showed the highest validity and reliability in PhysioMaster assessments.
- Hip and knee ROM had moderate to good inter-method reliability but poor agreement with goniometric measurements.
- PhysioMaster is consistent for remote tracking of ROM changes, especially for hip and knee movements.

## Abstract

The PhysioMaster application showed strong validity and inter-method reliability for ankle plantarflexion.

Hip and knee ROM demonstrated limited validity but showed moderate to good inter-method reliability between in-person and online assessments.

What are the main findings?
The validity of the sensor-based mobile application is confirmed only for ankle plantarflexion.Sensor-based applications show comparable measurements when applied in-person and online for most lower-limb joints.

The validity of the sensor-based mobile application is confirmed only for ankle plantarflexion.

Sensor-based applications show comparable measurements when applied in-person and online for most lower-limb joints.

What are the implications of the main findings?
PhysioMaster has the potential to be used for monitoring changes in ROM online due to ease of use and consistent numbers in person and online.Smartphone sensor-based tools like PhysioMaster offer promising support for remote musculoskeletal assessment for longitudinal ROM tracking.

PhysioMaster has the potential to be used for monitoring changes in ROM online due to ease of use and consistent numbers in person and online.

Smartphone sensor-based tools like PhysioMaster offer promising support for remote musculoskeletal assessment for longitudinal ROM tracking.

The increasing use of telerehabilitation has intensified the need for validated smartphone sensor-based tools capable of accurately capturing joint range of motion (ROM). This study examined the criterion validity of the PhysioMaster application compared with a universal goniometer during in-person assessments and evaluated the inter-method reliability between in-person and online PhysioMaster measurements. Thirty healthy young adults underwent standardized hip, knee, and ankle ROM testing using both approaches. The criterion validity was limited for most joints, with only ankle plantarflexion demonstrating the highest validity and dorsiflexion showing a moderate association; in contrast, hip and knee ROM exhibited poor agreement with goniometric values. Despite limited absolute agreement, PhysioMaster demonstrated moderate to good inter-method reliability for hip and knee ROM, indicating consistency across assessment modes. These findings suggest that while PhysioMaster may not serve as a direct substitute for in-person goniometry, it shows potential as a consistent tool for tracking ROM changes remotely, particularly for hip and knee movements. The application may support remote musculoskeletal monitoring within telerehabilitation contexts where repeated, standardized assessments are required.