title: Spinal Realignment for Adult Deformity: Three-column Osteotomies Alter Total Hip Acetabular Component Positioning.
abstract: BACKGROUND
  A goal of adult spinal deformity surgery is correction of sagittal imbalance by increasing lumbar lordosis (LL), allowing a previously retroverted pelvis to normalize as evidenced by decreases in pelvic tilt (PT). Realignment of pelvic orientation may alter the position of preexisting total hip arthroplasties (THAs).
  
  
  METHODS
  Twenty-seven patients with unilateral THA who underwent thoracolumbar fusions for adult spinal deformity from the pelvis to L1 or above were retrospectively reviewed (levels fused, 10.3 [range, 6 to 17]; age, 70 ± 9 years). Comparisons of preoperative and postoperative spinal deformity parameters, acetabular tilt (AT), and acetabular cup abduction angle (CAA) were performed, with subgroup analysis for those who had undergone three-column osteotomy and those who had not.
  
  
  RESULTS
  Preoperative deformity was severe, with findings of a sagittal vertical axis >9 cm, PT >25°, and pelvic incidence-LL >20°. Postoperatively, AT decreased significantly (-7° ± 10°; P < 0.001), signifying relative acetabular retroversion. Comparing patients with three-column osteotomy versus those without, AT changes were greater in those with three-column osteotomy (11° ± 7° and -2 ± 10°, respectively; P = 0.024). AT was significantly correlated with changes of PT (r = 0.704; P < 0.001) and LL (r = -0.481; P = 0.011). AT decreased (ie, retroverted) 1° for every 3.23° of LL or 1.13° of PT correction. The coronal plane CAA did not change substantially.
  
  
  CONCLUSIONS
  Spinal deformity correction, with techniques such as three-column osteotomy, result in significant THA acetabular component repositioning in the sagittal plane. Resultant decreased AT (ie, retroversion) theoretically may affect tribology, wear, and joint stability and warrants further investigation.
authors.affiliation: From the Department of Orthopaedic Surgery (Dr. Barry, Dr. Yucekul, Dr. Theologis, Dr. Hansen, and Dr. Deviren) and the Department of Neurosurgery (Dr. Ames), University of California, San Francisco, CA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Barry
authors.forename: Altug
authors.initials: A
authors.lastname: Yucekul
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Theologis
authors.forename: Erik N
authors.initials: EN
authors.lastname: Hansen
authors.forename: Christopher
authors.initials: C
authors.lastname: Ames
authors.forename: Vedat
authors.initials: V
authors.lastname: Deviren
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D012189:Retrospective Studies; D013121:Spinal Curvatures / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D013904:Thoracic Vertebrae / Q000601:surgery*; D016896:Treatment Outcome