Surface Topography and Radiographic Spinal Damage in Radiographic Axial Spondyloarthritis

September 28, 2026 updated by: Seyma Alkan, Ankara Etlik City Hospital

Association Between Static Spinal Posture Assessed by Surface Topography (DIERS) and Radiographic Structural Damage (mSASSS) in Radiographic Axial Spondyloarthritis: A Cross-Sectional Study

Radiographic axial spondyloarthritis (r-axSpA) causes progressive structural damage of the spine, conventionally quantified on lateral cervical and lumbar radiographs using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Repeated radiography entails cumulative radiation exposure, substantial inter-reader variability and low sensitivity in early disease. DIERS Formetric 4D surface topography provides radiation-free three-dimensional modelling of the spine and pelvis. The association between sagittal balance and structural damage has been demonstrated with a radiation-based system (EOS), but whether a radiation-free topographic method reflects the same association has not been investigated.

This single-centre, cross-sectional observational study will enrol 53 adults with r-axSpA fulfilling the ASAS criteria with radiographic sacroiliitis according to the modified New York criteria. At a single study visit, static DIERS Formetric 4D measurements, chest expansion, BASMI, BASDAI, BASFI and ASDAS-CRP are obtained. mSASSS is scored by two independent readers, blinded to clinical and topographic data, on existing lateral cervical and lumbar radiographs obtained within the preceding 12 months; no additional radiographs are performed for the study. The primary analysis is the correlation between total mSASSS and the DIERS fleche cervicale (cervical sagittal anterior displacement).

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Design: single-centre, cross-sectional, non-interventional correlation study in a single patient group; no control group. All participant data are collected in one assessment session lasting approximately 45 to 60 minutes.

Measurements: (a) demographic and anthropometric data; (b) disease duration, age at symptom onset, comorbidities, extra-articular involvement (uveitis, inflammatory bowel disease, psoriasis), HLA-B27 status, current medication category; (c) radiographic sacroiliitis grade according to the modified New York criteria and mSASSS (range 0 to 72), scored independently by two blinded readers with inter-reader agreement reported as the intraclass correlation coefficient; (d) chest expansion; (e) BASDAI, BASFI and ASDAS-CRP, the latter using routine C-reactive protein values with no additional blood sampling; (f) BASMI total score and its five components; (g) DIERS Formetric 4D static parameters: fleche cervicale (cervical sagittal anterior displacement, mm), sagittal imbalance (mm and degrees), coronal imbalance (mm), pelvic obliquity (mm), pelvic torsion (degrees), cervical and lumbar depth distance (mm), kyphotic angle (degrees) and lordotic angle (degrees).

Statistical analysis: distribution is assessed with the Shapiro-Wilk test. The primary analysis is a Pearson or Spearman correlation between total mSASSS and fleche cervicale, reported with effect size and 95% confidence interval, followed by multiple linear regression adjusted for age and disease duration. Secondary analyses comprise correlations of DIERS parameters with clinical indices and an exploratory receiver operating characteristic analysis of the ability of DIERS sagittal parameters to predict prespecified mSASSS thresholds. The Benjamini-Hochberg procedure is applied to correct for multiple comparisons. Significance is set at p<0.05. Analyses are performed with IBM SPSS version 23 or later.

Sample size: calculated with G*Power 3.1.9 for a bivariate normal correlation model, two-tailed, rho H0 = 0, expected effect size r = 0.40, alpha = 0.05 and power = 0.85, giving a required sample of 53 participants (actual power 0.857). The effect size was set conservatively at r = 0.40 rather than the r = 0.61 reported by Wanders et al.

(2005) for occiput-to-wall distance versus mSASSS, because DIERS parameters are not identical to clinical mobility measures.

Reporting follows the STROBE statement.

Study Type

Observational

Enrollment (Estimated)

53

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

Study Contact Backup

Study Locations

  • Turkey (Türkiye)
    • Yenimahalle
      • Ankara, Yenimahalle, Turkey (Türkiye), 06560
        • Recruiting
        • Ankara Etlik City Hospital, Department of Physical Medicine and Rehabilitation
        • Contact:

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

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Consecutive patients with radiographic axial spondyloarthritis attending the spondyloarthritis outpatient clinic of the Department of Physical Medicine and Rehabilitation, Ankara Etlik City Hospital.

Description

Inclusion Criteria:

  • Age 18 to 65 years
  • Diagnosis of radiographic axial spondyloarthritis fulfilling the ASAS criteria, confirmed by radiographic sacroiliitis according to the modified New York criteria
  • Able to provide written informed consent and to complete the assessments
  • Available lateral cervical and lumbar radiographs obtained within the 12 months preceding the DIERS measurement

Exclusion Criteria:

  • Neurological disease affecting balance, posture or gait (for example Parkinson disease, amyotrophic lateral sclerosis, cerebellar or vestibular disorders, history of stroke)
  • History of lower extremity joint arthroplasty (hip or knee)
  • Orthopaedic conditions affecting posture, balance or gait (ununited fracture, previous spinal or lower extremity surgery)
  • Advanced cardiopulmonary disease, active infection or malignancy
  • Pregnancy

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

  • Observational Models: COHORT
  • Time Perspectives: CROSS_SECTIONAL

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Radiographic axial spondyloarthritis patients

Adults aged 18 to 65 years with radiographic axial spondyloarthritis fulfilling the ASAS classification criteria with radiographic sacroiliitis according to the modified New York criteria, attending the spondyloarthritis outpatient clinic. All participants undergo a single assessment session including static DIERS Formetric 4D surface topography, clinical indices (BASDAI, BASFI, BASMI, ASDAS-CRP) and chest expansion. mSASSS is scored on existing lateral cervical and lumbar radiographs obtained within the preceding 12 months; no additional radiographs are taken.
Diagnostic test: DIERS Formetric 4D surface topography

Radiation-free three-dimensional assessment of spinal and pelvic surface topography performed once in standing position. No radiation, no contact, no intervention on treatment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Correlation between total mSASSS and DIERS fleche cervicale
Time Frame: Single assessment session (Day 1); mSASSS scored on radiographs obtained within the 12 months preceding the assessment

Total modified Stoke Ankylosing Spondylitis Spine Score (mSASSS; range 0 to 72, higher scores indicate greater structural damage), calculated as the mean of two independent blinded readers, correlated with fleche cervicale (cervical sagittal anterior displacement, mm) measured by DIERS Formetric 4D surface topography. Reported as a correlation coefficient with magnitude, direction and 95% confidence interval.
Single assessment session (Day 1); mSASSS scored on radiographs obtained within the 12 months preceding the assessment

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Correlation between total mSASSS and other DIERS Formetric static parameters
Time Frame: Single assessment session (Day 1); mSASSS scored on radiographs obtained within the 12 months preceding the assessment

Total mSASSS (range 0 to 72, higher scores indicate greater structural damage) correlated with the remaining DIERS Formetric 4D static parameters: sagittal imbalance (mm and degrees), coronal imbalance (mm), pelvic obliquity (mm), pelvic torsion (degrees), cervical depth distance (mm), lumbar depth distance (mm), kyphotic angle (degrees) and lordotic angle (degrees). Reported as correlation coefficients with 95% confidence intervals.
Single assessment session (Day 1); mSASSS scored on radiographs obtained within the 12 months preceding the assessment
Correlation between DIERS sagittal parameters and BASDAI
Time Frame: Single assessment session (Day 1)

Bath Ankylosing Spondylitis Disease Activity Index (range 0 to 10, higher scores indicate greater disease activity) correlated with DIERS sagittal parameters.
Single assessment session (Day 1)
Correlation between DIERS sagittal parameters and BASFI
Time Frame: Single assessment session (Day 1)

Bath Ankylosing Spondylitis Functional Index (range 0 to 10, higher scores indicate worse physical function) correlated with DIERS Formetric 4D static parameters: fleche cervicale (mm), sagittal imbalance (mm and degrees), coronal imbalance (mm), pelvic obliquity (mm), pelvic torsion (degrees), cervical and lumbar depth distance (mm), kyphotic angle (degrees) and lordotic angle (degrees).
Single assessment session (Day 1)
Correlation between DIERS sagittal parameters and BASMI
Time Frame: Single assessment session (Day 1)

Bath Ankylosing Spondylitis Metrology Index (range 0 to 10, higher scores indicate worse spinal mobility) correlated with DIERS Formetric 4D static parameters: fleche cervicale (mm), sagittal imbalance (mm and degrees), coronal imbalance (mm), pelvic obliquity (mm), pelvic torsion (degrees), cervical and lumbar depth distance (mm), kyphotic angle (degrees) and lordotic angle (degrees).
Single assessment session (Day 1)
Correlation between DIERS sagittal parameters and ASDAS-CRP
Time Frame: Single assessment session (Day 1)

Ankylosing Spondylitis Disease Activity Score with C-reactive protein (higher scores indicate greater disease activity) correlated with DIERS Formetric 4D static parameters: fleche cervicale (mm), sagittal imbalance (mm and degrees), coronal imbalance (mm), pelvic obliquity (mm), pelvic torsion (degrees), cervical and lumbar depth distance (mm), kyphotic angle (degrees) and lordotic angle (degrees).
Single assessment session (Day 1)
Correlation between DIERS sagittal parameters and chest expansion
Time Frame: Single assessment session (Day 1)

Chest expansion measured in centimetres correlated with DIERS Formetric 4D static parameters: fleche cervicale (mm), sagittal imbalance (mm and degrees), coronal imbalance (mm), pelvic obliquity (mm), pelvic torsion (degrees), cervical and lumbar depth distance (mm), kyphotic angle (degrees) and lordotic angle (degrees).
Single assessment session (Day 1)
Discriminative performance of DIERS sagittal parameters for mSASSS thresholds
Time Frame: Single assessment session (Day 1); mSASSS scored on radiographs obtained within the 12 months preceding the assessment

Exploratory receiver operating characteristic analysis of DIERS Formetric 4D sagittal parameters for discriminating prespecified total mSASSS thresholds. Reported as area under the curve with 95% confidence interval, sensitivity and specificity.
Single assessment session (Day 1); mSASSS scored on radiographs obtained within the 12 months preceding the assessment

Collaborators and Investigators

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

Sponsor

Ankara Etlik City Hospital

Investigators

  • Principal Investigator: Ajda Bal, Professor of Physical Medicine and Rehabilitation

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

Helpful Links

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)

September 19, 2026

Primary Completion (Estimated)

June 20, 2027

Study Completion (Estimated)

August 20, 2027

Study Registration Dates

First Submitted

September 28, 2026

First Submitted That Met QC Criteria

September 28, 2026

First Posted (Actual)

October 2, 2026

Study Record Updates

Last Update Posted (Actual)

October 2, 2026

Last Update Submitted That Met QC Criteria

September 28, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AEŞH-BADEK1-2026-048

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared. According to the approved protocol, research data are accessible only to the investigators. Aggregate results will be published.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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