Abstract
Background
Vertebral rotation is an important parameter in adolescent idiopathic scoliosis as it affects the hump and thus the esthetic aspect of the deformity. Nonetheless, it is one of the least explored parameters due to the difficulty of assessment using conventional AP and lateral standing radiographs and the high radiation of CT-scans. With the advent of EOS® technology, vertebral rotation is easily assessed using the 3D reconstruction with high accuracy and low irradiation. The objective of this study is to evaluate the apical vertebral rotation and study its correlation to the pelvic parameters.
Materials and Methods
This is a descriptive transversal study. 73 patients with adolescent idiopathic scoliosis patients (Cobb > 10°) aged between 9 and 36 years old with no prior history of spinal operation at initial examination were included. Subjects underwent antero-posterior and lateral radiographs of the whole spine and pelvis using the EOS® system. On the AP radiograph, the thoracic curve angle, the lumbar curve angle and the number of the involved vertebrae were measured. On the lateral view, pelvic incidence was measured. The rotation of the apical vertebra was obtained by stereoradiographic 3D reconstruction of the spine.
Results
The mean age of the cohort was 14 years and 11 months and 90% were females. The mean Cobb of the primary curve was 38.98 (16.9–104) with a mean vertebral rotation of 15.5° (0.3–43.5°). The mean Cobb of the compensatory curve was 31.35 (9.2–64°) with a mean vertebral rotation of 9.32° (0.1°-40.5°). While the apical vertebral rotation showed a strong correlation to the Cobb angle of the affected curve (r = 0.72, p < 0.001 for the main curve; r = 0.74, p < 0.001 for the compensatory curve), it correlated moderately to the pelvic incidence (r = 0.31; p < 0.05). Furthermore, apical vertebral rotation had the most strong correlation to pelvic incidence in thoracic curves (apex T5-T10; r=0.4, p < 0.05), whether in lumbar curves (apex L2-L4) there were a tendency to a negative correlation (r = −0.2, p > 0.05). Finally, the pelvic incidence did not correlate to the curve Cobb angle (r = 0.34, p = 0.08 for the primary curve; r = 0.27, p = 0.055 for the compensatory curve)
Conclusions
To our knowledge, this is the first study evaluating the correlation between apical vertebral rotation and pelvic incidence. Pelvic incidence is a well-known pelvic parameter that correlates significantly to the apical vertebral rotation in adolescent idiopathic scoliosis.