Assessing cervical rotation in ankylosing spondylitis: iPhone Compass versus traditional tools

Area of Science:

• Rheumatology
• Biomedical Engineering
• Medical Device Technology

Background:

• Ankylosing spondylitis (AS) is a chronic inflammatory condition affecting the spine.
• Accurate measurement of cervical rotation (CR) is crucial for monitoring AS progression and treatment efficacy.
• Traditional measurement tools like inclinometers and goniometers can be cumbersome and require specialized training.

Purpose of the Study:

• To evaluate the reliability of the iPhone's built-in Compass application for measuring CR in AS patients.
• To compare the iPhone Compass app's measurements against established methods (inclinometer, universal goniometer).

Main Methods:

• 30 AS patients were recruited from a rheumatology outpatient clinic.
• Two examiners performed CR measurements twice using the iPhone Compass app, inclinometer, and universal goniometer.
• Intrarater and interrater reliability were assessed using intraclass correlation coefficients (ICCs).
• Agreement between methods was analyzed using the Bland-Altman method.

Main Results:

• Excellent intrarater and interrater reliability were found for all three measurement methods.
• Good agreement was observed between the iPhone Compass app and the inclinometer.
• The iPhone Compass app demonstrated acceptable agreement with the universal goniometer, with minor mean differences.

Conclusions:

• The iPhone Compass application is a reliable and practical tool for measuring CR in AS patients.
• Integrating smartphone technology offers an accessible and potentially cost-effective solution for clinical assessment.
• This technology holds promise for enhancing patient monitoring and clinical practice in rheumatology.