title: Reliability of Sagittal Spinopelvic Alignment Measurements After Total Hip Arthroplasty.
abstract: METHODS
  This is a observational study.
  
  
  OBJECTIVE
  To evaluate the reliability of measuring sagittal spinopelvic alignment after hip arthroplasty.
  
  
  BACKGROUND
  Pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), and lumbar lordosis (LL) are widely used in planning the treatment of people with spinal and hip disorders. Previously, these measures have proved reliable when hip heads are intact. Thus far, it is not known whether they are also reliable after total hip replacement.
  
  
  METHODS
  Two observers assessed PI, SS, PT, and LL in the radiographs of 97 patients who had undergone total hip replacement. Test-retest (intraobserver) and interobserver reliability were estimated.
  
  
  RESULTS
  The intraclass correlation coefficient ranged from 0.92 to 0.97 and 0.85 to 0.94 for the intraobserver and interobserver settings, respectively, indicating an almost perfect correlation between observers or observations. The absolute intrarater measurement errors were 1.41 [95% confidence interval (CI), 0.98-2.03) for PI, 1.16 (95% CI, 0.78-1.74) for SS, 0.49 (95% CI, 0.31-0.76) for PT, and 1.75 (95% CI, 1.22-2.51) degrees for LL. The respective interrater figures were 2.82 (95% CI, 2.04-3.9), 2.44 (95% CI, 1.78-3.35), 0.73 (95% CI, 0.48-1.13), and 2.28 (95% CI, 1.55-3.34) degrees.
  
  
  CONCLUSIONS
  It seems that total hip arthroplasty does not affect the reliability of spinopelvic sagittal alignment measurements.
  
  
  METHODS
  Level II.
authors.affiliation: Departments of *Orthopedics and Traumatology †Physical and Rehabilitation Medicine, Turku University Hospital and University of Turku, Turku, Finland.
authors.forename: Katri
authors.initials: K
authors.lastname: Pernaa
authors.forename: Matti
authors.initials: M
authors.lastname: Seppänen
authors.forename: Keijo
authors.initials: K
authors.lastname: Mäkelä
authors.forename: Mikhail
authors.initials: M
authors.lastname: Saltychev
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006801:Humans; D008141:Lordosis / Q000503:physiopathology; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008297:Male; D015588:Observer Variation; D010388:Pelvis / Q000503:physiopathology*; D015203:Reproducibility of Results; D012447:Sacrum / Q000503:physiopathology; D013131:Spine / Q000503:physiopathology*