Smartphone-based accelerometry is a valid tool for measuring dynamic changes in knee extension range of motion

Area of Science:

• Biomechanics
• Rehabilitation Technology
• Orthopedics

Background:

• Static range of motion measurements are standard in orthopedics but lack detail on patient impairments.
• Dynamic range of motion (ROM) assessment offers more comprehensive patient data for improved clinical insights.
• Current dynamic ROM measurement technology has limitations, restricting its clinical use.

Purpose of the Study:

• To validate smartphone-based accelerometry for measuring dynamic knee joint range of motion.
• To assess the accuracy of accelerometry against a gold-standard method for dynamic knee extension.

Main Methods:

• Dynamic knee extension range of motion was measured in 21 healthy males.
• Measurements were taken using an isokinetic dynamometer (gold-standard) and a smartphone (iPhone 6) attached to the tibia.
• Passive knee extension motion was generated using an isokinetic dynamometer.

Main Results:

• Smartphone accelerometry demonstrated excellent correlation (rs=0.899) with the isokinetic dynamometer.
• A low standard error of measurement (0.62°) and narrow limits of agreement (-9.1° to 8.8°) were observed.
• Excellent between-measures reliability (ICC>0.862) was found for both measurement methods.

Conclusions:

• Smartphone-based accelerometry is a valid and reliable tool for assessing dynamic knee extension range of motion.
• This technology provides a simple, low-cost, and clinically applicable method for dynamic knee ROM assessment.
• Clinicians can utilize this method for enhanced patient evaluations and treatment monitoring.