Scoliosis is a three-dimensional deformity (coronal, axial, and sagittal), so it makes sense that a 3-D imaging method for evaluating the condition and measuring the impact of surgical correction would outperform traditional two-dimensional imaging techniques. That’s exactly what Newton et al. found in their Level II diagnostic study in the October 21, 2015 edition of The Journal of Bone & Joint Surgery.
The authors analyzed 3-D and 2-D images from 120 patients with adolescent idiopathic scoliosis (AIS), before and after surgery with segmented thoracic pedicle-screw instrumentation. The mean preoperative Cobb angle on the standard 2-D view was 55° ± 10°, while on the 3-D view it was 52° ± 9° (p ≤ 0.001). The mean T5-T12 kyphosis on the 2-D view measured 18° ± 13° preoperatively and 27° ± 6° postoperatively, while the mean T5-T12 kyphosis on the 3-D view measured 6° ± 14° preoperatively and 26° ± 6° postoperatively. The difference between the 2-D and 3-D measurements of T5-T12 kyphosis strongly correlated with apical vertebral rotation.
The significant preoperative overrepresentation of the T5-T12 kyphosis on standard 2-D imaging compared with 3-D assessments led the authors to conclude that “the sagittal profile evaluated by the standard lateral view is unreliable and often results in a false sense of thoracic kyphosis.” They go on to claim that “measurement with the 3-D, segmental local vertebral approach can be a useful, surgeon-oriented method for evaluating the deformity of scoliosis as well as the correction associated with surgical treatment.”