Vertebral Rotation In Adolescent Idiopathic Scoliosis Research Articles

A Novel Method for Estimating Three-Dimensional Apical Vertebral Rotation Using Two-Dimensional Coronal Cobb Angle and Thoracic Kyphosis

Study DesignRetrospective cohort analysis. ObjectivesTo use a large cohort of three-dimensional (3D) spinal reconstructions to create a simple mathematical formula capable of estimating 3D apical vertebral rotation (AVR) based on the correlation with routinely obtained two-dimensional (2D) measurements of scoliosis. Summary of Background DataQuantification of vertebral rotation in AIS using 2-dimensional (2D) imaging is inherently challenging as the axial plane cannot be directly visualized. MethodsA database of 279 3D spinal reconstructions was queried for patients with thoracic major adolescent idiopathic scoliosis (AIS). 2D thoracic Cobb angle, T5–T12 thoracic kyphosis, pelvic incidence, sacral slope, and pelvic tilt were recorded. 3D AVR was calculated for each patient from 3D reconstructions. Patients were divided into development (n = 186) and validation (n = 93) cohorts. Within the development cohort, univariate analysis was performed between 2D measurements and 3D AVR with significance set at p < .05 for inclusion in multivariate analysis. In multivariate analysis, significance was set at p < .01 for inclusion in the final model. Model performance was tested in development and validation cohorts. ResultsOnly 2D thoracic Cobb and T5–T12 thoracic kyphosis had significance in univariate (p < .05) and multivariate analyses (p < .01), meriting inclusion in the final model. 3D AVR (°) = 0.26*(T5–T12 kyphosis) + 0.34*(coronal Cobb) − 5.38. In the development cohort, the model performed well (R = 0.739, r2 = 0.54). In testing with the validation cohort, the model proved generalizability (R = 0.703) and had a mean absolute error <5°. ConclusionsThis model is capable of estimating 3D AVR given 2D thoracic Cobb and T5–T12 kyphosis. The accuracy of this method is comparable to previously reported methods of 2D axial rotation measurement. However, this model provides 3D axial rotation and requires no physical instruments, non-standard measurements, or software programs. Such a model is valuable for both routine evaluation of AIS and operative preparation. Level of EvidenceLevel II, diagnostic.

Development and assessment of a digital X-ray software tool to determine vertebral rotation in adolescent idiopathic scoliosis

Background ContextThe amount of vertebral rotation in the axial plane is of key importance in the prognosis and treatment of adolescent idiopathic scoliosis (AIS). Current methods to determine vertebral rotation are either designed for use in analogue plain radiographs and not useful in digital images, or lack measurement precision and are therefore less suitable for the follow-up of rotation in AIS patients. PurposeThis study aimed to develop a digital X-ray software tool with high measurement precision to determine vertebral rotation in AIS, and to assess its (concurrent) validity and reliability. Study Design/settingIn this study a combination of basic science and reliability methodology applied in both laboratory and clinical settings was used. MethodsSoftware was developed using the algorithm of the Perdriolle torsion meter for analogue AP plain radiographs of the spine. Software was then assessed for (1) concurrent validity and (2) intra- and interobserver reliability. Plain radiographs of both human cadaver vertebrae and outpatient AIS patients were used. Concurrent validity was measured by two independent observers, both experienced in the assessment of plain radiographs. Reliability-measurements were performed by three independent spine surgeons. ResultsPearson correlation of the software compared with the analogue Perdriolle torsion meter for mid-thoracic vertebrae was 0.98, for low-thoracic vertebrae 0.97 and for lumbar vertebrae 0.97. Measurement exactness of the software was within 5° in 62% of cases and within 10° in 97% of cases. Intraclass correlation coefficient (ICC) for inter-observer reliability was 0.92 (0.91–0.95), ICC for intra-observer reliability was 0.96 (0.94–0.97). ConclusionsWe developed a digital X-ray software tool to determine vertebral rotation in AIS with a substantial concurrent validity and reliability, which may be useful for the follow-up of vertebral rotation in AIS patients.

Comparison of Vertebral Rotation Corrected by Different Techniques and Anchors in Surgical Treatment of Adolescent Thoracic Idiopathic Scoliosis

Evaluation of radiographs and computed tomography in patients undergoing different surgical interventions for adolescent idiopathic scoliosis (AIS). To compare the correction of vertebral rotation by different surgical techniques and/or anchors in the treatment of AIS. The technique and the technology used in the surgical treatment of AIS continue to evolve; there is little information about the comparison of the vertebral rotation correction of thoracic scoliosis by different surgical techniques and/or anchors. A retrospective study was performed on 106 consecutive patients with AIS, who underwent selective thoracic fusion with different surgical techniques and/or anchors, including hooks, wires, and pedicle screws on the periapical concave side from a posterior approach and an anterior approach using screws. The selection criteria were as follows: younger than 20 years of age, thoracic scoliosis (Lenke type 1, 2, and 3), selected thoracic fusion, and a minimum 2-year follow-up period, whereas thoracic hyperkyphosis was excluded. The patients were classified into group A (anterior approach, n=27), group H (hooks, n=39), group S (screws, n=25), and group W (wires, n=15). The Cobb angle and apical vertebral rotation were evaluated by plain radiography and computed tomography, respectively, before and after surgery and after 2 years of follow-up. All 4 groups were matched for age, sex, preoperative major curve, and curve flexibility. In all groups, the coronal Cobb angle was significantly improved after surgery, without any significant differences between the 4 groups. The Rotation Angle midline values in group A, group H, and group S were significantly improved after 2 years of follow-up (P<0.01), but not for group W. Rotation Angle sagittal was significantly improved after 2 years only in group A. Classification of each group into 2 subgroups according to the flexibility index (>0.5 and <0.5) provided Rotation Angle sagittal values that demonstrated significant improvement postoperatively (P<0.01) for group A and group S subgroups with a flexibility index >0.5. Compared with the use of hooks and the wires, vertebral rotation in AIS is effectively corrected by either the anterior approach or posterior pedicle screw fixation, especially in patients with more flexible scoliosis (a flexibility index >0.5).