Objective To present a new principle for correction of the sagittal plane of the spine through the convergent or divergent placement of monoaxial pedicle screws in this plane, associated with compression or distraction, to provide lordotizing or kyphotizing leverage force. Method A statistical mechanical study of twenty-eight fixations in synthetic spine segments was performed. In fifteen pieces, pedicle screws were applied to the ends of the segments with positioning convergent to the center of the fixation. They were attached to the straight rods and subjected to compression force. The other thirteen segments were fixed with pedicle screws in a direction divergent to the center of the fixation, attached to the straight rods, and subjected to distraction force. Results To create kyphosis in the 15 synthetic segments of the spine, the mean pre-fixation Cobb angle was - 0.7° and the mean post-fixation angle was +15°. To create lordosis in the 13 segments, the mean pre-fixation Cobb angle was +1° and the mean post-fixation angle was +18°. The difference was confirmed by statistical mechanical tests and considered significant. However, there is no relevant difference between the mean angles for lordosis and kyphosis formation. Conclusions It was concluded that the correction of the sagittal plane of the spine by applying the new instrumentation method is efficient. A statistical mechanical test confirmed that the difference in Cobb degrees between pre- and post-fixation of the synthetic spine segments was considered significant in the creation of both kyphosis and lordosis. Level of evidence II C; Statistical mechanical study of synthetic spine segments.

Objective: To conduct a comparative study of the results obtained in the treatment of adolescent idiopathic scoliosis (AIS) with different types of fixations (traditional, selective and multiple), and to evaluate the correction of angular deformity in the frontal plane by the Cobb and sacral clavicular angle (SCA) methods. Methods: A study of a group of 278 patients with AIS who underwent selective, traditional, and multiple fixation surgeries. Results: Significant corrections of both the Cobb angle and the SCA were observed. Conclusions: In the multiple fixation surgeries there was a 100% correction between the preoperative and postoperative SCA values and a 50% correction in the traditional and selective fixations, a difference considered significant. Regarding the Cobb angle, the three fixations presented corrections between preop and postop with significant differences. Level of evidence III; Retrospective Study.

Objective: To evaluate the postoperative loss of scoliosis correction using third-generation instrumental, comparing the immediately postoperative period, and the last visit of the patients operated on from 2002 to 2010. Method: This was a cross-sectional study, conducted by analysis of medical records, in which 45 patients undergoing scoliosis correction were included. Variables were evaluated preoperatively, immediately postoperatively and in the last follow-up visit after surgery. Statistical analysis of data was performed in PASW program, with a significance level of 95%. Results: Among the 45 patients studied, 88.9% were female and 82.8% were in the skeletally immature group. The mean pre-operative Cobb was 57°, the postoperative was 6.5° and at the last visit, it was 7.04°. There was no statistic difference between postoperative Cobb angle and that at the last examination (p = 0.176). Conclusion: There was no significant loss of scoliosis correction loss between the immediate postoperative and the final radiographic evaluation.Keywords: Scoliosis/diagnosis; Scoliosis/surgery; Scoliosis/radiography; Surgical procedures, operative; Bone screws.