Study Design. 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.
Summary of Background Data. 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).
Conclusion. 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.
Level of Evidence: III
A new method allowed characterizing 3-dimensional spinopelvic alignment in adolescent idiopathic scoliosis (AIS). The proposed parameters of the pelvic orientation are related to both thoracic and lumbar spinal deformities. This method is complementary to the sagittal sacropelvic indices and can be used to typify the pelvic orientation in AIS subgroups.
*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.
Address correspondence and reprint requests to Carl-Eric Aubin, PhD, PEng, Department of Mechanical Engineering, Polytechnique Montreal, PO Box 6079, Station “Centre-ville,” Montréal, Quebec, H3C 3A7 Canada; E-mail: carl-eric.aubin@polymtl
Acknowledgment date: December 20, 2012. First revision date: April 30, 2013. Second revision date: August 30, 2013. Third revision date: October 3, 2013. Acceptance date: October 28, 2013.
The manuscript submitted does not contain information about medical device(s)/drug(s).
Natural Sciences and Engineering Research Council of Canada: Industrial research Chair with Medtronic of Canada grant funds were received in support of this work.
Relevant financial activities outside the submitted work: grants, travel/accommodations/meeting expenses, consultancy.