An Investigation of the Effect of Smartphone Usage Levels on Cervical Posture, Tongue Pressure, Balance, and Neck Disability in Individuals With Rheumatoid Arthritis and Ankylosing Spondylitis

The purpose of this cross-sectional and comparative study is to investigate the impact of smartphone addiction on the cervical posture, musculoskeletal system, balance, and tongue pressure in individuals diagnosed with Rheumatoid Arthritis (RA) and Ankylosing Spondylitis (AS), and to compare these findings with a healthy control group. Smartphone addiction has become a major contributing factor to postural alterations such as Text Neck Syndrome. This study aims to evaluate and compare the Craniovertebral Angle (CVA), neck extensor muscle strength, Pressure Pain Thresholds (PPT) of the neck and shoulder, Single-Leg Stance (SLS) static balance, and tongue pressure among three distinct groups. A healthy control group will be included as a reference baseline to differentiate the postural and functional deterioration caused by rheumatological diseases from the additional mechanical load imposed by smartphone dependency. To eliminate the misleading effects of acute pain, joint swelling, and severe functional limitations during flare-ups, only patients with stable disease activity (DAS28 \< 3.2 for RA and BASDAI \< 4 for AS) will be enrolled. This approach aims to examine the pure biomechanical relationship between technological dependency and cervical functions, independent of active systemic inflammation.