Apical vertebral derotation and translation (AVDT) for adolescent idiopathic scoliosis using screws and sublaminar bands: a safer concept for deformity correction

Does the addition of convex uniplanar screws in hybrid constructs improve 3D surgical correction in thoracic adolescent idiopathic scoliosis posterior fusion?

Purpose

Hybrid techniques using thoracic sublaminar bands have proved their efficacy in adolescent idiopathic scoliosis posterior fusion, but clinical axial correction sometimes remained disappointing. One solution found was "the frame technique" and the second alternative was the replacement of the convex sublaminar bands by periapical uniplanar screws. The goal of this study was to compare clinical and radiological outcomes of both techniques in a consecutive cohort of adolescent idiopathic scoliosis patients.

Methods

All patients undergoing primary posterior fusion for thoracic adolescent idiopathic scoliosis between January 2017 and March 2020 were included. Two groups were compared: Group 1 with thoracic sublaminar bands only and Group 2 with periapical uniplanar screws. All patients underwent standing stereoradiographs. The main frontal, sagittal, and axial (apical vertebra rotation) radiological parameters of interest were analyzed. Functional outcomes were assessed using the Scoliosis Research Society 30 score.

Results

A total of 147 adolescents were included (Group 1, n = 73 and Group 2, n = 74 patients). In the frontal plane, a greater reduction index was observed in Group 2 (68% versus 62%, p < 0.001) as well as a better apical axial correction (67.8% versus 46.6%, p = 0.03). The number of thoracoplasty performed was reduced (6.7% versus 20.5%, p = 0.02) in Group 2, with a significant decrease in the rate of mechanical complication. No significant loss of correction was observed during follow-up in any of the group.

Conclusion

The adjunction of convex uniplanar screws at the periapical levels improved the three-dimensional surgical correction of thoracic adolescent idiopathic scoliosis treated with hybrid constructs.

Level of evidence

level III, retrospective comparative study.

The Relationship Between Compliance of Physiotherapeutic Scoliosis Specific Exercises and Curve Regression With Mild to Moderate Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective Case-control Study.

OBJECTIVES

To determine the requisite exercise compliance (EC) of physiotherapeutic scoliosis-specific exercise (PSSE) for achieving curve regression; to analyze whether the apical translation (AT), apical wedging (AW), and apical rotation (AR) of the major curve improve with regression effect.

METHODS

Between 2019 and 2021, a total of 763 patients undertook a 6-month PSSE treatment. This resulted 426 compliable and 302 uncompliable patients remained available for analysis. For compliable patients, 213 with curve regression and 213 age-/sex-matched with curve stabilization/deterioration at the 6-month, were eligible for regression analysis to detect the relationship between EC and regression effect at the 6-month; receiver operating characteristic (ROC) curve analysis and Youden's index were applied to identify the threshold of EC leading to curve regression at the 6-month. The AT, AW, and AR of the major curve were compared before and after 6-month PSSE to investigate the radiographic parameters that improved with regression effect.

RESULTS

EC was correlated with regression effect (odds ratio: 19.9, 95% confidence interval: 11.3-35.0, P < .001) and the cutoff threshold of EC was 4.4 h/week for 6 months to realize such an effect. AT was improved by 47.6% with curve regression, in which 152 cases remained curve regression and no case progressed into the operative threshold at the 1.5- to 2-year.

CONCLUSIONS

A 6-month PSSE protocol of 4.4 hours per week was potentially leading to curve regression in treating mild to moderate scoliosis. An improvement in AT of the major curve was observed with the regression effect.

Is posteromedial translation with sublaminar bands effective in correcting axial rotation in adolescent idiopathic scoliosis surgery? A 3D reconstruction study

PURPOSE

Hybrid constructs with sublaminar bands have recently regained popularity as an alternative to all-screw construct for correction of adolescent idiopathic scoliosis (AIS). The aim of this study is to evaluate the ability of hybrid constructs with sublaminar bands to achieve a tridimensional correction of the scoliotic deformity. Our hypothesis is that hybrid construct with sublaminar bands are able to achieve a substantial derotation of the apical vertebrae, while preserving the thoracic kyphosis.

METHODS

A prospective evaluation of 50 consecutive cases (41 F, 9 M, mean age 14.7 ± 2 years) of AIS correction with hybrid construct was performed. In all cases, sublaminar bands were used at the apex of the main curve on concave side. All patients underwent pre and postoperative X-rays with EOS System, with full 3D reconstruction. Spinopelvic parameters and axial rotation of the vertebrae were measured pre and postoperatively.

RESULTS

2.7 ± 0.9 mean sublaminar bands were used per patient. Mean correction of deformity was 50 ± 9.5%. on the coronal plane. The mean axial rotation of the apical vertebra went from 18° ± 11.5° preoperatively to 9.4° ± 7.2° postoperatively (p < 0.001) with a mean derotation of 47.7%. Thoracic kyphosis went from 32.1° ± 18° preoperatively to 37.3° ± 13.1° postoperatively (p < 0.05). No intraoperative complications due to sublaminar bands were recorded.

CONCLUSIONS

Hybrid construct with sublaminar band have been showed to be safe and effective in deformity correction and in maintaining or restoring thoracic kyphosis. This study showed that with sublaminar bands applied at the curve apex a substantial derotation of the apical vertebrae can be achieved.

Incidence and Risk Factors of Cervical Kyphosis in Patients with Adolescent Idiopathic Scoliosis

BACKGROUND

Cervical kyphosis (CK) has been reported in patients with adolescent idiopathic scoliosis (AIS). The report about the incidence of CK between patients with AIS and normal populations was little. Patients included in previous studies often required scoliosis surgery (Cobb angle ≥40°), which does not represent all patients with AIS. The aims of this study were to compare incidence of CK between patients with AIS (Cobb angle >10°) and an age-matched normal population and to identify risk factors related to CK, especially coronal parameters that have rarely been studied in current literature.

METHODS

Patients with AIS (n = 112) and asymptomatic subjects from the general population (control group; n = 40) were retrospectively analyzed. Radiographic parameters of coronal and sagittal plane were measured on full-length spine x-rays. Patients with AIS were divided into 2 groups based on cervical lordosis angle: cervical lordosis and CK.

RESULTS

CK was observed in 14 of 40 (35%) subjects in the control group and 68 of 112 (60.7%) patients with AIS. Several parameters were related to CK, including major curve, proximal thoracic, and main thoracic Cobb angle; proximal thoracic kyphosis angle; main thoracic kyphosis angle; T1 slope; sagittal vertical axis; vertical distance between C7 plumb line and center sacral vertical line; apical vertebral translation; T1 coronal tilt; and lumbar pelvic relationship. Logistic regression identified main thoracic Cobb angle, main thoracic kyphosis angle, sagittal vertical axis, lumbar pelvic relationship, and apical vertebral translation as independent risk factors of CK.

CONCLUSIONS

Incidence of CK increases in patients with AIS relative to normal subjects. Coronal parameters of the spine could influence cervical sagittal alignment.