Can I Really Use My Phone to Measure Joint Range of Motion?
A Comparison of Smartphone Apps with traditional measurement tools
Introduction
Measuring joint range of motion (ROM) is a cornerstone of assessment in physical therapy and kinesiology. With the rise of smartphone technology, free apps now offer clinicians an accessible way to obtain ROM measurements. But how do these digital tools compare to traditional tools like goniometers and digital inclinometers? In this article, we explore recent research highlighting the impressive accuracy of smartphone apps, discuss their benefits, and compare them with purpose-built goniometers and inclinometers—all while keeping the focus on empowering you to choose the best tool for your unique circumstances.
Accuracy of Smartphone Apps: Research at a Glance
Recent studies have provided robust evidence supporting the use of smartphone apps for ROM measurement. In one study (PMC8987335), researchers reported intraclass correlation coefficients (ICC) of up to 0.98 for intra-rater reliability when comparing smartphone app measurements with traditional goniometers. These figures indicate an almost perfect agreement, with differences often falling within 1–2° of the goniometer values—a margin that is well within acceptable clinical limits.
Another study (PMC10392163) echoed these findings, demonstrating that smartphone apps not only matched the accuracy of standard goniometers but, in some cases, even reduced measurement variability. When averaged across multiple joint movements, the mean difference between smartphone app readings and goniometric measurements was minimal, reinforcing the notion that these apps can serve as reliable tools in both research and clinical practice.
A systematic review (ScienceDirect, S2666638322000986) further confirmed that free smartphone apps can be both cost-effective and accurate, offering a practical alternative for many clinical settings without compromising on reliability. Additionally, comparative analysis (ScienceDirect, S0894113017302594) has shown that when it comes to measuring joint angles, smartphone apps perform admirably—even under less-than-ideal conditions.
My experience with the using phone apps.
Hey, you might be thinking, "Wait, doesn't Kevin Cairns at Metriks sell inclinometers? Why is he telling me about free apps?"
Great question! The goal here is to empower you with knowledge so that you can choose the right tool for your specific needs.
As an example when I’m teaching at University, say like Kin 1430 Functional Ability Evaluation at the University of Guelph-Humber, and covering joint ROM, many of my undergraduate students simply can’t afford expensive professional devices—they have food, rent, and other expenses to worry about. For them, and even in many clinical settings, downloading a free smartphone app provides an excellent learning tool and a reliable means of measurement.
So what do I like?
- Free! That make this accessible to anyone with a phone.
- On most Apple phones look for the Measurement app/Level
- For Android you will need to download an App
- It’s always close at hand.
- What do I find challenging
- Phones are too thin. Making them difficult to hold steady.
- Phones are too big. Making them difficult to hold flat on say the top of the head when measuring cervical ROM
That said, there are many, many scenarios when taking a phone from your pocket and being able to measure range of motion is the best option. It is a quick and easy way to collect objective data to inform your treatment plan.
Conclusion
Emerging research robustly supports the use of smartphone apps as reliable and accurate tools for assessing joint ROM. With ICC values nearing perfection and mean measurement differences well within clinically acceptable ranges, these apps are an excellent addition to the clinical toolkit. At the same time, dedicated digital inclinometers offer features that enhance stability and ease-of-use, making them ideal for situations where even a minor error could have significant consequences.
Ultimately, the choice between smartphone apps and digital inclinometers comes down to your unique circumstances and clinical needs. Whether you're teaching students or working with patients in a busy clinic, having a range of tools at your disposal means you can always select the one that best meets your objectives.
References
- Meza Solutions Digital Inclinometer: https://mezasolutions.ca/products/digital-inclinometer
- Study on Smartphone App Reliability and Validity: PMC8987335
- Additional Research on ROM Measurement Using Smartphones: PMC10392163
- Systematic Review on Smartphone Apps for ROM Assessment: ScienceDirect S2666638322000986
- Comparative Analysis of Measurement Tools in ROM Assessment: ScienceDirect S0894113017302594
