BACKGROUND: Obtaining accurate measurements of scoliosis from two-dimensional (2-D) radiographs can be challenging because of the three-dimensional (3-D) nature of the deformity. Previous studies have shown that the sagittal plane, in particular, is misrepresented on 2-D radiographs because of the influence of @entity717 . The purpose of the current study was to define a methodology for measuring the 3-D segmental sagittal alignment of the spine in @entity1 with @entity1615 ( @entity1615 ) and to assess the effect of @entity717 on differences between 3-D and 2-D measures of deformity. METHODS: Preoperative and postoperative EOS images of 120 consecutive @entity1 with @entity1615 (primary thoracic curves) treated with segmental thoracic pedicle-screw instrumentation were analyzed in the "3-D sagittal plane." The technique measured 3-D @entity1513 or @entity1515 in the specific plane of sagittal motion for each spinal motion segment. The @entity1513 (+) and @entity1515 (-) values of the segments from T5 to T12 were summed to give the 3-D measurement of T5-T12 @entity1513 . These values were compared with the standard 2-D measurements of T5-T12 @entity1513 on lateral radiographs, and a correlation analysis with regard to @entity717 of the apex was performed. RESULTS: The average age (and standard deviation) of the @entity1 was 14    2 years. The mean preoperative Cobb angle on the standard 2-D view was 55      10   and on the 3-D view was 52      9   (p  <= 0.001). On the 3-D view, the mean preoperative T5-T12 @entity1513 was 6      14  , and the @entity1513 significantly increased to 26      6   postoperatively (p < 0.001). The T5-T12 @entity1513 on the standard 2-D view measured 18      13   preoperatively and 27      6   postoperatively (p < 0.001). The difference between the 2-D and 3-D measurements of T5-T12 @entity1513 strongly correlated with apical @entity717 (r = 0.85; p < 0.01). CONCLUSIONS: Routine 2-D measurements of @entity1513 erroneously underestimate the preoperative @entity393 in @entity1615 because of errors associated with @entity717 , an inherent component of @entity1514 . LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Defining the "Three-Dimensional Sagittal Plane" in XXXX .

@entity1 :: ('9606', 'Species') :: ['patients'] @entity1615 :: ('OMIM:181800', 'Disease') :: ['AIS', 'adolescent idiopathic scoliosis'] @entity1513 :: ('MESH:D007738', 'Disease') :: ['thoracic kyphosis', 'kyphosis'] @entity1514 :: ('MESH:D013896', 'Disease') :: ['thoracic scoliosis'] @entity1515 :: ('MESH:D008141', 'Disease') :: ['lordosis'] @entity717 :: ('MESH:D009069', 'Disease') :: ['axial plane rotation', 'vertebral rotation'] @entity393 :: ('MESH:D034381', 'Disease') :: ['loss of kyphosis']
@entity1615 :: (OMIM:181800,Disease) :: ['Thoracic Adolescent Idiopathic Scoliosis']
