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.
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.
Study Type
OBSERVATIONAL
Enrollment
50
Fatih Sultan Mehmet Training and Research Hospital
Istanbul, Turkey (Türkiye)
Fatih Sultan Mehmet Training and Research Hospital
Istanbul, Turkey (Türkiye)
Sacral Slope (SS)
Sacral slope will be measured on standardized lateral radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Pelvic Tilt (PT)
Pelvic tilt will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Pelvic Incidence (PI)
Pelvic Incidence will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Spinosacral Angle (SSA)
Spinosacral Angle will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Sacral Kyphosis (SK)
Sacral Kyphosis will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Sacral Table Angle (STA)
Sacral Table Angle will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Thoracic Kyphosis (TK)
Thoracic Kyphosis will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Lumbar Lordosis (LL)
Lumbar Lordosis will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Sagittal Vertical Axis (SVA)
Sagittal Vertical Axis will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Thoracolumbar Angle (TPA-T1PA)
Thoracolumbar Angle will be measured on sagittal radiographs in both standing and sitting positions.
Time frame: At baseline (single time point)
Coccygeal Morphology- Vertebral Segment Number
Coccygeal features will be evaluated
Time frame: At baseline (single time point)
Coccygeal Morphology- sacrococcygeal joint fusion
Coccygeal features will be evaluated
Time frame: At baseline (single time point)
Coccygeal Morphology- intercoccygeal joint fusion
Coccygeal features will be evaluated
Time frame: At baseline (single time point)
Coccygeal Morphology- segmental angulation
Coccygeal features will be evaluated
Time frame: At baseline (single time point)
Coccygeal Morphology- presence of coccygeal spicules
Coccygeal features will be evaluated
Time frame: At baseline (single time point)
Coccygeal Morphometry Type
Classification (Type 1-5)
Time frame: At baseline (single time point)
Coccygeal Mobility
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.
Time frame: At baseline (single time point)
Sacrococcygeal Angle (SKA)
SKA will be measured using the angle between the sacral axis and first coccygeal segment on lateral radiographs.
Time frame: At baseline (single time point)
Intercoccygeal Angle (IKA)
IKA will be measured as the angle between coccygeal segments
Time frame: At baseline (single time point)
Coccygeal Height (KY)
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.
Time frame: At baseline (single time point)
Sacral Height (SY)
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.
Time frame: At baseline (single time point)
Sacrococcygeal Height (SKY)
Combined vertical height from sacral promontory to coccyx.
Time frame: At baseline (single time point)
Clinical Assessment- Pain severity
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.
Time frame: At baseline (single time point)
Clinical Assessment - Quality of Life (SF-12)
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).
Time frame: At baseline (single time point)
Clinical Assessment - Disability - Oswestry Disability Index (ODI) Score
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.
Time frame: At baseline (single time point)
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