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Completed

NCT Number: NCT07076927

Sagittal Spinopelvic and Coccygeal Alignment in Sitting and Standing Positions in Coccydynia

This observational cross-sectional study aims to investigate the differences in spinopelvic and coccygeal morphometric parameters in standing and sitting positions among patients diagnosed with coccydynia. A total of 50 adult patients (aged 25-65 years) diagnosed with coccydynia based on clinical evaluation and imaging findings were included. Lateral radiographs were obtained in both standing and sitting positions. Radiological assessments included spinopelvic parameters such as sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), sacral table angle (STA), and sacral kyphosis (SK), along with coccygeal morphology based on the Postacchini-Massobrio classification. The study further aimed to explore whether these morphometric differences are associated with the presence of low back pain and to assess variations across different coccygeal morphology types.

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Key information

Conditions

Coccydynia Morphological Analysis and Classification Sagittal Balance

Age range

25 year–65 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey (Türkiye)

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About this study

Coccydynia is a condition characterized by pain in the coccygeal region, often exacerbated by sitting and postural changes. While its etiology is multifactorial, anatomical variations in coccygeal and spinopelvic alignment may play a significant role in symptom development. Despite increasing attention to coccygeal mobility and morphology in radiological evaluations, the relationship between coccygeal type, spinopelvic alignment, and posture-specific morphometric changes has not been fully clarified.

This observational cross-sectional study was designed to evaluate morphometric parameters of the sacropelvic and coccygeal regions in both standing and sitting positions in patients diagnosed with coccydynia. The study included 50 adult patients (42 female, 8 male) aged between 25 and 65 years who were diagnosed with coccydynia based on clinical findings and radiological confirmation. Lateral radiographs were obtained in both weight-bearing and seated positions to allow for comparative measurement.

The following radiological parameters were assessed: thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), thoracopelvic angle and its modification (TPA-T1PA), sacral slope (SE), pelvic incidence (PI), pelvic tilt (PT), spinosacral angle (SSA), sacral table angle (STA), and sacral kyphosis (SK). Coccygeal features were evaluated based on vertebral segment number, sacrococcygeal and intercoccygeal joint fusion, segmental angulation, and mobility status. Morphological types were categorized using the modified Postacchini-Massobrio classification. The presence of coccygeal spicules and their frequency across types were recorded. Dynamic morphometric assessments included sacrococcygeal angle (SKA), intercoccygeal angle (IKA), coccygeal height (KY), sacral height (SY), and sacrococcygeal height (SKY). Mobility was determined by comparing the angular displacement between standing and sitting radiographs and classified as normal, hypermobile, hypomobile, or posterior luxation, depending on the flexion-extension response and translation under load.The study aimed to investigate the changes in these parameters between postures and explore whether these variations are associated with the presence of low back pain and functional impairment. Additionally, differences among coccygeal morphology subgroups in terms of spinopelvic parameters were analyzed.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Patients aged between 25 and 65 years

Clinically diagnosed with coccydynia

Provided informed consent to participate in the study

Exclusion criteria

Presence of any disease that may cause spinal malalignment

Any hip- or knee-related condition that may lead to spinal malalignment

History of surgery involving the cervical, thoracic, lumbar, or coccygeal spine

Treatment and study plan

Primary outcomes

  1. Sacral Slope (SS)

    Time frame: At baseline (single time point)

    Sacral slope will be measured on standardized lateral radiographs in both standing and sitting positions.

  2. Pelvic Tilt (PT)

    Time frame: At baseline (single time point)

    Pelvic tilt will be measured on sagittal radiographs in both standing and sitting positions.

  3. Pelvic Incidence (PI)

    Time frame: At baseline (single time point)

    Pelvic Incidence will be measured on sagittal radiographs in both standing and sitting positions.

  4. Spinosacral Angle (SSA)

    Time frame: At baseline (single time point)

    Spinosacral Angle will be measured on sagittal radiographs in both standing and sitting positions.

  5. Sacral Kyphosis (SK)

    Time frame: At baseline (single time point)

    Sacral Kyphosis will be measured on sagittal radiographs in both standing and sitting positions.

  6. Sacral Table Angle (STA)

    Time frame: At baseline (single time point)

    Sacral Table Angle will be measured on sagittal radiographs in both standing and sitting positions.

  7. Thoracic Kyphosis (TK)

    Time frame: At baseline (single time point)

    Thoracic Kyphosis will be measured on sagittal radiographs in both standing and sitting positions.

  8. Lumbar Lordosis (LL)

    Time frame: At baseline (single time point)

    Lumbar Lordosis will be measured on sagittal radiographs in both standing and sitting positions.

  9. Sagittal Vertical Axis (SVA)

    Time frame: At baseline (single time point)

    Sagittal Vertical Axis will be measured on sagittal radiographs in both standing and sitting positions.

  10. Thoracolumbar Angle (TPA-T1PA)

    Time frame: At baseline (single time point)

    Thoracolumbar Angle will be measured on sagittal radiographs in both standing and sitting positions.

  11. Coccygeal Morphology- Vertebral Segment Number

    Time frame: At baseline (single time point)

    Coccygeal features will be evaluated

  12. Coccygeal Morphology- sacrococcygeal joint fusion

    Time frame: At baseline (single time point)

    Coccygeal features will be evaluated

  13. Coccygeal Morphology- intercoccygeal joint fusion

    Time frame: At baseline (single time point)

    Coccygeal features will be evaluated

  14. Coccygeal Morphology- segmental angulation

    Time frame: At baseline (single time point)

    Coccygeal features will be evaluated

  15. Coccygeal Morphology- presence of coccygeal spicules

    Time frame: At baseline (single time point)

    Coccygeal features will be evaluated

  16. Coccygeal Morphometry Type

    Time frame: At baseline (single time point)

    Classification (Type 1-5)

  17. Coccygeal Mobility

    Time frame: At baseline (single time point)

    Coccygeal mobility will be assessed by measuring the angular difference of the coccyx between the standing and sitting positions on lateral radiographs. The change in coccygeal angle reflects the degree of coccygeal movement during postural transition.

  18. Sacrococcygeal Angle (SKA)

    Time frame: At baseline (single time point)

    SKA will be measured using the angle between the sacral axis and first coccygeal segment on lateral radiographs.

  19. Intercoccygeal Angle (IKA)

    Time frame: At baseline (single time point)

    IKA will be measured as the angle between coccygeal segments

  20. Coccygeal Height (KY)

    Time frame: At baseline (single time point)

    The vertical height of the coccyx from the tip to the base will be measured in the sagittal plane.

    ertical height of the coccyx from the tip to the base will be measured in the sagittal plane.

    Vertical height of the coccyx from the tip to the base will be measured in the sagittal plane.

  21. Sacral Height (SY)

    Time frame: At baseline (single time point)

    Vertical sacral height will be assessed from the superior to the inferior sacral end on the lateral radiograph.

    ertical height of the coccyx from the tip to the base will be measured in the sagittal plane.

    Vertical height of the coccyx from the tip to the base will be measured in the sagittal plane.

  22. Sacrococcygeal Height (SKY)

    Time frame: At baseline (single time point)

    Combined vertical height from sacral promontory to coccyx.

Secondary outcomes

  1. Clinical Assessment- Pain severity

    Time frame: At baseline (single time point)

    Unit of Measure: Units on a Numeric Rating Scale (0-10) Description: Pain severity will be assessed using the Numeric Rating Scale (NRS), where 0 indicates no pain and 10 indicates the worst imaginable pain.

  2. Clinical Assessment - Quality of Life (SF-12)

    Time frame: At baseline (single time point)

    Unit of Measure: SF-12 Score (0-100) Description: General health-related quality of life will be evaluated using the 12-Item Short Form Survey (SF-12).

  3. Clinical Assessment - Disability - Oswestry Disability Index (ODI) Score

    Time frame: At baseline (single time point)

    Unit of Measure: Score (0-100)

    Description:

    Functional disability related to low back pain will be assessed using the Oswestry Disability Index (ODI). The ODI is a validated questionnaire consisting of 10 sections, each scored from 0 to 5. The total score is converted to a percentage, with higher scores indicating greater disability.

Sponsors and collaborators

Lead sponsor

Fatih Sultan Mehmet Training and Research Hospital

Other

Registry information

Official study title

Sagittal Radiographic Analysis of Spinopelvic and Coccygeal Alignment in Sitting and Standing Positions in Patients With Coccydynia

Acronym: Coccydynia

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
Jul 22, 2025
Registry last updated
Jul 22, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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