Abstract:
Purpose: Transverse plane pelvic rotation has been implicated in the pathogenesis of adolescent idiopathic scoliosis (AIS). In
vitro, transverse plane pelvic rotation can be determined by a ratio of the radiographic coronal plane hemi-pelvis widths. The purposes of this study are to determine the reliability of this technique on standing 36 inch radiographs and the relationship of transverse plane pelvic rotation to curve direction and location.
Methods: Pre-operative posterior-anterior radiographs of 305 consecutively operated patients were reviewed and those with
full pelvis exposure, 197 (65%) studied; including patients with AIS 167/241, congenital scoliosis 15/33, isthmic
spondylolisthesis 7/18, and Scheuermann’s 8/13. AIS patients' curves were grouped by Lenke classification. Intra- and
inter-rater reliability (ICC) was calculated and significance of rotation was done using One-sample Student’s t-test.
Results: Intra- and inter-rater reliabilities were 0.97 and 0.88. Scheuermann’s and spondylolisthesis groups had no transverse plane pelvic rotation. Lenke type 1 AIS curves (n=68) had clockwise pelvic rotation, (p< 0.0001), the same as their thoracic curve. Congenital thoracic curves (n=15) also had clockwise pelvic rotation (p=0.028). Lenke type 2, 3, 4, 5, or 6 curves showed no correlation between their direction of pelvic rotation and scoliosis curve rotation.
Conclusion: This radiographic measurement technique of transverse plane pelvic rotation is reliable. Clockwise pelvic
rotation correlates significantly with clockwise thoracic rotation/scoliosis for both adolescent idiopathic and congenital
scoliosis. This supports the hypothesis that transverse plane pelvic rotation may be involved in the pathogenesis of thoracic
scoliosis, but not other patterns, at least as currently classified.
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