title: Preoperative Planning for Pedicle Subtraction Osteotomy: Does Pelvic Tilt Matter?
abstract: METHODS
  Multicenter, retrospective radiographic analysis.
  
  
  OBJECTIVE
  To evaluate the impact that preoperative spinopelvic parameters have on postoperative sagittal vertical axis (SVA). The researchers hypothesized that patients with a large preoperative pelvic tilt (PT) would require more extensive lumbar pedicle subtraction osteotomy (LPSO) procedures to reestablish anatomic postoperative SVA than patients with normal preoperative PT.
  
  
  BACKGROUND
  Restoration of anatomic sagittal spinal alignment has been demonstrated to improve clinical outcomes. However, the degree to which spinopelvic parameters contribute to sagittal spinal malalignment is poorly understood.
  
  
  METHODS
  Multicenter, retrospective analysis of 183 consecutively enrolled adult spinal deformity patients treated with LPSO procedures for correction of sagittal malalignment. Preoperative and postoperative freestanding full-length sagittal X-rays were analyzed for regional curves, pelvic parameters, and global alignment. Only patients with a preoperative SVA greater than 10 cm and a postoperative SVA less than 5 cm were retained for analysis. Patients were divided into 2 groups according to preoperative PT (low PT, less than 30°; and high PT, ≥30°). Independent t test analysis was used to determine differences in correction required to achieve postoperative SVA less than 5 cm.
  
  
  RESULTS
  A total of 55 patients were identified for analysis. Low PT (n = 30) had lower preoperative PT than high PT (n = 25; 25° vs. 42°, respectively; p < .001). Analysis of the osteotomy performed demonstrated that the high PT group required a larger osteotomy resection (30° vs. 23°; p = .039) and a larger correction of lumbar lordosis (-43° vs. -31°; p = .006) to achieve an acceptable postoperative SVA (less than 5 cm).
  
  
  CONCLUSIONS
  This study demonstrates that patients with high PT in conjunction with sagittal spinal malalignment require larger lumbar osteotomy procedures, including a greater osteotomy resection and larger lumbar lordosis correction, to obtain a satisfactory postoperative SVA. Surgeons performing LPSO procedures must evaluate preoperative spinopelvic parameters, including PT, to avoid undercorrection and residual deformity after complex sagittal realignment procedures.
authors.affiliation: Spine Division, NYU Hospital for Joint Diseases, 306 E 15th Street, New York, NY 10003, USA. Electronic address: virginie.lafage@gmail.com.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
authors.affiliation: Spine Division, NYU Hospital for Joint Diseases, 306 E 15th Street, New York, NY 10003, USA; Universite Aix-Marseille, Marseille, 3 Place Victor Hugo, 13331 Marseille Cédex 3, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Blondel
authors.affiliation: Neurological Surgery, University of Virginia, 1215 Lee Street, Charlottesville, VA 22903, USA.
authors.forename: Justin S
authors.initials: JS
authors.lastname: Smith
authors.affiliation: Orthopedic Surgery, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021, USA.
authors.forename: Oheneba
authors.initials: O
authors.lastname: Boachie-Adjei
authors.affiliation: Orthopedic Surgery, Baylor Scoliosis Center, 4708 Alliance Blvd #800, Plano, TX 75093, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Hostin
authors.affiliation: Department of Orthopedic Surgery, University of Kansas Medical Center, 3901 Rainbow Blvd, Kansas City, KS 66160, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Burton
authors.affiliation: San Diego Center for Spinal Disorders, 4130 La Jolla Village Dr, La Jolla, CA 92037, USA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Mundis
authors.affiliation: Department of Orthopedic Surgery, University of California, Davis Medical Center, 2315 Stockton Blvd, Sacramento, CA 95817, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Klineberg
authors.affiliation: Department of Neurological Surgery, University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Ames
authors.affiliation: San Diego Center for Spinal Disorders, 4130 La Jolla Village Dr, La Jolla, CA 92037, USA.
authors.forename: Behrooz
authors.initials: B
authors.lastname: Akbarnia
authors.affiliation: Orthopedic Center, Rocky Mountain Hospital for Children, 1719 E 19th Ave, Denver, CO 80218, USA.
authors.forename: Shay
authors.initials: S
authors.lastname: Bess
authors.affiliation: Spine Division, NYU Hospital for Joint Diseases, 306 E 15th Street, New York, NY 10003, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Schwab
keywords: Osteotomy; Pelvic tilt; Preoperative planning; Radiographic outcomes; Sagittal malalignment