Reliability of Smartphone Inclinometry to Measure Upper Cervical Range of Motion

Assessment of upper cervical range of motion (UCROM) and mobility is commonly performed in the clinical setting for patients suffering from headache, neck pain, and vestibular dysfunction. Reliable and reproducible measurement of this motion is often difficult or too expensive to perform in the clinical setting. Smartphone applications using the device's internal gyroscope offer an easy and inexpensive means of measuring UCROM, but their reliability has not been reported in the literature.

To assess the reliability of an inclinometer application installed on 2 different devices (iPhone 6 [IP] and android [AN]) and to measure UCROM in a healthy population.

Two examiners assessed passive UCROM. Each examiner was assigned to a specific smartphone, and a repeated-measures design consisting of 3 trials for each examiner-phone was performed. The order of testing was randomized, and the examiners were blinded to UCROM measures.

Laboratory.

A total of 38 subjects (19 females and 19 males; age: 23.8 [1.2] y) without pain or injury to the neck or spine for at least 3 months.

Each examiner passively flexed the head fully, rotated the head fully in 1 direction, and then in another. Peak rotation measures were recorded from each smartphone. Three trials were performed for each phone, with a 2-minute break between examiners/phones.

Intraclass correlation coefficient using a 2-way mixed, absolute agreement model was obtained (1) between each examiner-phone and (2) within each examiner-phone for the measurements in each rotation direction.

Interphone/examiner reliability comparing average peak and total UCROM for each device was excellent (.87, .81). Intraphone/examiner reliability, determined across 3 trials, was also excellent (AN right rot. = .91, AN left rot. = .96; IP right rot. = .98, IP left rot. = .95).

UCROM can be reliably measured using a smartphone inclinometer application.