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

June 5, 2026 updated by: Merve Şahin

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.

Study Overview

Status

Recruiting

Conditions

Detailed Description

This study is designed as a cross-sectional, comparative, and correlational investigation conducted at the Necmettin Erbakan University Faculty of Medicine Hospital, Rheumatology Outpatient Clinic. The study population will consist of three groups, each comprising 37 participants (Total N = 111): the Rheumatoid Arthritis (RA) group, the Ankylosing Spondylitis (AS) group, and a Healthy Control (HC) group. Participants will be recruited using consecutive sampling according to their eligibility.

Following the written informed consent process in accordance with the Declaration of Helsinki, a single-session comprehensive assessment protocol will be conducted by an experienced physiotherapist. No therapeutic interventions or follow-up procedures will be performed.

The structured evaluation protocol will be executed in the following chronological order:

Sociodemographic and Descriptive Information Form: Participants will be questioned regarding age, sex, height, body weight, marital status, educational level, smoking habits, medical history, disease duration, active medications, sports participation, daily smartphone/computer/tablet usage duration, and habitual posture/ergonomics during technology use.
Neck Disability Index (NDI): Symptoms and functional limitations will be evaluated using the Turkish validated version of the NDI (Aslan & Karaduman, 2009). Scoring ranges from 0 to 50, where higher scores indicate greater functional disability.
Smartphone Addiction Scale-Short Version (SAS-SV): Technological dependency will be assessed using the Turkish validated version of the SAS-SV (Noyan et al., 2015). Cut-off values of 31 for males and 33 for females will be utilized to determine addiction status.
Craniovertebral Angle (CVA) Measurement: To objectively assess forward head posture, goniometric measurement will be performed. Anatomical reference points (the spinous process of the C7 vertebra and the tragus of the ear) will be marked. The goniometer center will be aligned with C7, with the stationary arm perpendicular to the ground and the movable arm aligned with the tragus. The average of three measurements with 2-minute rest intervals will be recorded. A CVA below 50° indicates Text Neck/forward head posture.
Neck Extensor Muscle Strength Test: While the participant sits upright, a digital handheld dynamometer probe will be placed at the occipital protuberance. Participants will perform a maximal isometric contraction pushing backward against the probe. The average of three trials with 30-60 second rest intervals will be recorded in Newtons (N).
Single-Leg Stance Test (SLST): Static balance performance will be evaluated on the non-dominant leg (stabilizing limb). The test will be performed three times with eyes open and three times with eyes closed, with a ceiling effect set at 60 seconds. The best scores will be recorded in seconds.
Pressure Pain Threshold (PPT) via Algometry: A digital algometer will be applied perpendicularly to the midpoint of the upper trapezius muscle and the suboccipital region. Pressure will be increased until the participant experiences the first sensation of pain. Two or three measurements will be averaged with 1-minute intervals to ensure reliability.
Tongue Pressure Assessment via IOPI: To evaluate the motor control of swallowing and suprahyoid muscle activity, the Iowa Oral Pressure Instrument (IOPI) will be utilized. An air-filled tongue bulb will be placed on the midline of the hard palate. Participants will press the bulb maximally against the palate for 5 seconds. The maximum value of three trials with 2-minute rest intervals will be recorded in Kilopascals (kPa).

Statistical analyses will be conducted to evaluate the negative correlations between smartphone addiction and functional parameters (CVA, muscle strength, PPT, balance, and tongue pressure), positive correlations with NDI, and to compare the physical deterioration between the clinical groups and healthy controls.

Study Type

Observational

Enrollment (Estimated)

111

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Name: Fatma ERDEO, Assistant Professor
Phone Number: +90505 443 17 78
Email: ferdeo@erbakan.edu.tr

Study Contact Backup

Name: Merve ŞAHİN, PT
Phone Number: +905528255101
Email: mervesahin5101@gmail.com

Study Locations

Turkey (Türkiye)
- Meram
  - Konya, Meram, Turkey (Türkiye), 42090
    - Recruiting
    - Necmettin Erbakan University Faculty of Medicine Hospital, Rheumatology Outpatient Clinic
    - Contact:
      
      Merve ŞAHİN, PT
      
      Phone Number: +905528255101
      
      Email: mervesahin5101@gmail.com
    - Contact:
      
      Mustafa Ç ERGÜN, MD, Assistant Professor
      
      Phone Number: +905055272690
      
      Email: bilgi@erbakan.edu.tr

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

Adult
Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The study population consists of adult patients diagnosed with Rheumatoid Arthritis (RA) and Ankylosing Spondylitis (AS) who are actively followed at the Rheumatology Outpatient Clinic of Necmettin Erbakan University Faculty of Medicine Hospital. Additionally, age-matched healthy volunteers recruited from the community with no systemic, neurological, or chronic musculoskeletal disorders will serve as the control group. All participants must fulfill the specific age criteria (18 to 65 years) and technological dependency baseline (using a smartphone for at least 2 hours daily).

Description

Inclusion Criteria:

Aged 18 to 65 years.
Using a smartphone for at least 2 hours daily.
Able to understand and follow postural commands during clinical measurements.
For the Rheumatoid Arthritis (RA) Group: Diagnosed with RA by a rheumatologist, with a stable disease activity score (DAS28 < 3.2).
For the Ankylosing Spondylitis (AS) Group: Diagnosed with AS by a rheumatologist, with a stable disease activity score (BASDAI < 4).

Exclusion Criteria:

History of prior surgical intervention in the cervical region.
Presence of neurological diseases (e.g., Parkinson's disease, ALS).
Severe visual or hearing impairment.
Vestibular system disorders.
Severe limitation in jaw opening.
Presence of acute neck trauma or malignancy.
Lower extremity amputation or advanced arthritis that prevents performing the balance test.
Active use of muscle relaxants or advanced sedative medications.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Number of groups / cohorts

Cohorts and Interventions

Group / Cohort
Rheumatoid Arthritis (RA) Group Patients diagnosed with Rheumatoid Arthritis by a rheumatologist, with a stable disease activity score (DAS28 < 3.2), aged 18-65, and using a smartphone for at least 2 hours daily.
Ankylosing Spondylitis (AS) Group Patients diagnosed with Ankylosing Spondylitis by a rheumatologist, with a stable disease activity score (BASDAI < 4), aged 18-65, and using a smartphone for at least 2 hours daily.
Healthy Control Group Healthy individual volunteers aged 18-65 with no history of rheumatological, neurological, or chronic musculoskeletal diseases, and using a smartphone for at least 2 hours daily.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Smartphone Addiction Scale-Short Version (SAS-SV) Time Frame: At baseline (Single assessment session)	The SAS-SV is a 10-item self-reported questionnaire used to evaluate the level of smartphone dependency. Each item is rated on a 6-point Likert scale ranging from 1 (strongly disagree) to 6 (strongly agree). Total scores range from 10 to 60. The cutoff scores were determined to be 31 for men and 33 for women, with higher scores indicating a higher risk and severity of smartphone addiction.	At baseline (Single assessment session)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Neck Disability Index (NDI) Time Frame: At baseline (Single assessment session)	The NDI is a 10-item questionnaire measuring neck pain-related disability and its impact on functional activities. Each item is scored from 0 (no disability) to 5 (total disability). Total scores range from 0 to 50, where higher scores represent greater functional neck impairment and disability. (0-4 points: no disability, 5-14 points: mild disability, 15-24 points: moderate disability, 25-34 points: severe disability, 35 points and above: complete disability)	At baseline (Single assessment session)
Craniovertebral Angle (CVA) Time Frame: At baseline (Single assessment session)	CVA will be measured in degrees using a manual goniometer to objectively assess forward head posture. The center of the goniometer will be placed on the C7 spinous process, with one arm vertical to the ground and the other pointing to the tragus of the ear. The average of three trials will be recorded. A lower angle indicates a greater severity of forward head posture (cutoff value is 50°).	At baseline (Single assessment session)
Single-Leg Stance Test (SLST) Performance Time Frame: At baseline (Single assessment session)	Static balance performance will be evaluated on the non-dominant leg with eyes open and eyes closed. The duration the participant maintains balance will be recorded in seconds, with a maximum ceiling effect of 60 seconds. Higher durations indicate better static balance stability.	At baseline (Single assessment session)
Neck Extensor Muscle Strength Time Frame: At baseline (Single assessment session)	Neck extensor strength will be evaluated using a digital handheld dynamometer placed at the level of the occipital protuberance while the participant sits upright. Participants will perform three maximal isometric contractions pushing backward, and the average value will be recorded in Newtons (N). Higher values indicate better muscle strength.	At baseline (Single assessment session)
Pressure Pain Threshold (PPT) Time Frame: At baseline (Single assessment session)	The PPT will be measured using a digital algometer applied perpendicularly to the midpoint of the upper trapezius muscle and the suboccipital region. Pressure will be increased gradually, and the value at which the participant feels the first sensation of pain will be recorded in kg/cm². Higher threshold values indicate less pain sensitivity.	At baseline (Single assessment session)
Maximum Tongue Pressure Time Frame: At baseline (Single assessment session)	Maximum isometric tongue pressure will be evaluated using the Iowa Oral Pressure Instrument (IOPI). Participants will press an air-filled rubber bulb placed at the midline of the hard palate as hard as possible for 5 seconds. The maximum value of three trials will be recorded in Kilopascals (kPa). Higher values represent greater tongue muscle strength.	At baseline (Single assessment session)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Merve Şahin

Investigators

Study Director: Fatma ERDEO, Assistant Professor, Necmettin Erbakan University Faculty of Health Sciences

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 9, 2026

Primary Completion (Estimated)

November 1, 2026

Study Completion (Estimated)

November 1, 2026

Study Registration Dates

First Submitted

May 31, 2026

First Submitted That Met QC Criteria

May 31, 2026

First Posted (Actual)

June 4, 2026

Study Record Updates

Last Update Posted (Actual)

June 9, 2026

Last Update Submitted That Met QC Criteria

June 5, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

30246.R1

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

IPD Plan Description

To ensure participant confidentiality and in accordance with the informed consent approved by the institutional ethics committee, individual participant data will not be shared with third parties or made publicly available outside of the primary research team.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Studies a U.S. FDA-regulated device product

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