title: Analysis of sagittal balance of ankylosing spondylitis using spinopelvic parameters.
abstract: METHODS
  Prospective study.
  
  
  OBJECTIVE
  To analyze sagittal spinopelvic parameters in ankylosing spondylitis (AS) patients.
  
  
  BACKGROUND
  There are little data on the relationship between the sagittal spinopelvic parameters and AS.
  
  
  METHODS
  The study and control groups comprised 90 AS patients and 40 controls. Participants were classified into 3 groups: normal (n=40), sagittal balance (n=58), and sagittal imbalance (n=32) groups. All underwent lateral radiograph of the whole spine including hip joints. The radiographic parameters were sacral slope, pelvic tilting, pelvic incidence, overhang of S1, thoracic kyphosis, lumbar lordosis, and C7 plumbline. Statistical analysis was performed to identify significant differences between the 2 groups. Correlations between radiological parameters and symptoms were sought.
  
  
  RESULTS
  AS patients and controls were found to be significantly different in terms of sagittal balance, sacral slope, pelvic tilt, pelvic incidence, S1 overhang, and lumbar lordosis. However, no significant difference was observed between these 2 groups for thoracic kyphosis (P>0.05). Of the 90 AS patients, 32 patients (5 women and 27 men) were assigned to the sagittal imbalance group and 58 (12 women and 46 men) to the sagittal balance group. There was a significant difference in all sagittal parameters and visual analogue scale (VAS) score between these 2 groups. Correlation analysis revealed significant relationships between sagittal parameters in AS. However, there was no association between sacral slope and S1 overhang, and between pelvic incidence and VAS score. Stepwise logistic regression analysis revealed that pelvic tilt contributed significantly to sagittal balance.
  
  
  CONCLUSIONS
  AS patients and normal controls were found to be significantly different in terms of sagittal spinopelvic parameters. Significant relationships were found between sagittal spinopelvic parameters in AS patients. Pelvic tilt was a significant parameter in determination of sagittal balance in AS patient. Furthermore, VAS scores were significantly related to sagittal spinal parameters which were closely related with pelvic orientation in AS patients.
authors.affiliation: *Department of Orthopaedic Surgery, Medical Research Institute, Pusan National University School of Medicine, Busan †Medical Research Institute, Department of Orthopaedic Surgery, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
authors.forename: Jung Sub
authors.initials: JS
authors.lastname: Lee
authors.forename: Kuen Tak
authors.initials: KT
authors.lastname: Suh
authors.forename: Jeung Il
authors.initials: JI
authors.lastname: Kim
authors.forename: Tae Sik
authors.initials: TS
authors.lastname: Goh
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*; D011859:Radiography; D012447:Sacrum / Q000000981:diagnostic imaging / Q000503:physiopathology; D013131:Spine / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging / Q000503:physiopathology*; D055815:Young Adult