title: Three-dimensional spinopelvic relative alignment in adolescent idiopathic scoliosis.
abstract: METHODS
  Three-dimensional (3D) analysis of the spinopelvic alignment in adolescent idiopathic scoliosis (AIS).
  
  
  OBJECTIVE
  To study the 3D pelvic alignment with respect to the spinal deformities in AIS subgroups.
  
  
  BACKGROUND
  Spinopelvic alignment is subject to change in scoliosis. Many sacropelvic parameters were developed to characterize spinopelvic alignment in the sagittal plane. However, not much is known about the 3D pelvic alignment with respect to the thoracic and lumbar spinal deformities in AIS.
  
  
  METHODS
  Eighty AIS subjects with right main thoracic (MT), 80 AIS with left thoracolumbar/lumbar (TL/L) curves, and 35 asymptomatic controls were included. Thoracic and lumbar Cobb angles, kyphosis, lordosis, pelvic incidence, pelvic tilt, and sacral slope were measured. Pelvic tilt and axial rotation in the coronal and transverse planes, respectively, were computed using the ipsilateral anterior superior iliac spine and posterior superior iliac spine positions. Leg length discrepancy was determined by the vertical difference in the position of the center of the femoral heads in the coronal plane.
  
  
  RESULTS
  In 59% of the MT subjects and 79% of the TL/L subjects in the erect position, the pelvis was tilted toward the convex side of the major curve in the coronal plane. The direction of the pelvic axial rotation in the transverse plane was in the same direction as the MT apical vertebra rotation in 84% of the MT subjects and 55% of the TL/L group. The pelvic incidence correlated to the lumbar lordosis in AIS (r = 0.41, P < 0.001). Pelvic coronal tilt correlated significantly to the leg length discrepancy in MT (r = 0.67) and TL/L (r = 0.61) subjects (P < 0.001).
  
  
  CONCLUSIONS
  Novel pelvic parameters were introduced to characterize the spinopelvic relative alignment in scoliotic subgroups. The proposed method related the orientation of the pelvis in the coronal and transverse planes to both thoracic and lumbar spinal deformities.
authors.affiliation: *Department of Mechanical Engineering, Polytechnique Montreal, Montréal, Quebec, Canada †Research Center, Sainte-Justine University Hospital Center, Montréal, Quebec, Canada ‡Department of Surgery, Université de Montréal, Montréal, Quebec, Canada; and §Division of Orthopedic Surgery, Hôpital du Sacré-Coeur de Montréal, Montréal, Quebec, Canada.
authors.forename: Saba
authors.initials: S
authors.lastname: Pasha
authors.forename: Carl-Eric
authors.initials: CE
authors.lastname: Aubin
authors.forename: Archana P
authors.initials: AP
authors.lastname: Sangole
authors.forename: Hubert
authors.initials: H
authors.lastname: Labelle
authors.forename: Stefan
authors.initials: S
authors.lastname: Parent
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Mac-Thiong
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae / Q000601:surgery*; D010384:Pelvic Bones / Q000601:surgery; D010388:Pelvis / Q000601:surgery; D011183:Postoperative Complications / Q000453:epidemiology; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000601:surgery*; D055815:Young Adult