Correlation Between Smartphone Use and Text Neck Posture in Asymptomatic Subjects

A mobile application called Screen Time Restrain Yourself measures smartphone usage in hours over the past week, allowing users to monitor their daily usage without disrupting normal smartphone use.

Photogrammetry is a reliable method for measuring head and cervical spine postures. It involves taking sagittal photographs of the subject's head tilt angle and neck tilt angle. A camera is positioned at a height corresponding to the seventh cervical vertebra (C7) level, and spherical markers are attached to the right tragus, canthus, and spinal process. The subject is instructed to sit on a chair, maintain a resting head posture, and perform full flexion and extension three times. The average of angles from repeated photos is used to reduce bias. Fatigue time is reported after ten minutes of use with a smartphone.

Cervical ROM is measured using a universal goniometer, with subjects placed flat on the floor and supported on a lap. They move their head in flexion and extension, with the goniometer placed over the external auditory meatus, fixed arm perpendicular to the floor, and movable arm with the nose base. For cervical rotation, they turn the head to the left or right side, and for lateral flexion, they touch the ear to a shoulder of the same side. The goniometer is a valid and reliable tool for measuring cervical ROM, with good interrater and intraterrater reliability.

The Neck Flexor Muscle Endurance Test (NFMET) involves a subject supine, with hands resting on the abdomen and feet flat on a plinth. The subject performs chin retraction, head and neck lift, and skin folds. The test measures muscle endurance, with males having a longer average hold time than females.