Brace treatment is the most common noninvasive treatment in adolescent idiopathic scoliosis (AIS); however it is currently not fully known whether there is a difference in effectiveness between brace types/concepts. All studies on brace treatment for AIS were searched for in PubMed and EMBASE up to January 2021. Articles that did not report on maturity of the study population were excluded. Critical appraisal was performed using the Methodological Index for Non-Randomized Studies tool (MINORS). Brace concepts were distinguished in prescribed wearing time and rigidity of the brace: full-time, part-time, and night-time, rigid braces and soft braces. In the meta-analysis, success was defined as ≤5° curve progression during follow-up. Of the 33 selected studies, 11 papers showed high risk of bias. The rigid full-time brace had on average a success rate of 73.2% (95% CI 61–86%), night-time of 78.7% (72–85%), soft braces of 62.4% (55–70%), observation only of 50% (44–56%). There was insufficient evidence on part-time wear for the meta-analysis. The majority of brace studies have significant risk of bias. No significant difference in outcome between the night-time or full-time concepts could be identified. Soft braces have a lower success rate compared to rigid braces. Bracing for scoliosis in Risser 0–2 and 0–3 stage of maturation appeared most effective.

In scoliosis, most of the deformity is in the disc and occurs during the period of rapid growth. The ring apophyses form the insertion of the disc into the vertebral body, they then ossify and fuse to the vertebrae during that same crucial period. Although this must have important implications for the mechanical properties of the spine, relatively little is known of how this process takes place. This study describes the maturation pattern of the ring apophyses in the thoracic and lumbar spine during normal growth. High-resolution CT scans of the spine for indications not related to this study were included. Ossification and fusion of each ring apophysis from T1 to the sacrum was classified on midsagittal and midcoronal images (4 points per ring) by two observers. The ring apophysis maturation (RAM) was compared between different ages, sexes, and spinal levels. The RAM strongly correlated with age (R = 0.892, p < 0.001). Maturation differed in different regions of the spine and between sexes. High thoracic and low lumbar levels fused earlier in both groups, but, around the peak of the growth spurt, in girls the mid-thoracic levels were less mature than in boys, which may have implications for the development of scoliosis.

Introduction: In idiopathic scoliosis, the anterior spinal column has rotated away from the midline and has become longer through unloading and expansion of the intervertebral discs. Theoretically, extension of the spine in the sagittal plane should provide room for this longer anterior spinal column, allowing it to swing back towards the midline in the coronal and axial plane, thus reducing both the Cobb angle and the apical vertebral rotation. Methods: In this prospective experimental study, ten patients with primary thoracic adolescent idiopathic scoliosis (AIS) underwent MRI (BoneMRI and cVISTA sequences) in supine as well as in an extended position by placing a broad bolster, supporting both hemi-thoraces, under the scoliotic apex. Differences in T4–T12 kyphosis angle, coronal Cobb angle, vertebral rotation, as well as shape of the intervertebral disc and shape and position of the nucleus pulposus, were analysed and compared between the two positions. Results: Extension reduced T4–T12 thoracic kyphosis by 10° (p < 0.001), the coronal Cobb angle decreased by 9° (p < 0.001) and vertebral rotation by 4° (p = 0.036). The coronal wedge shape of the disc significantly normalized and the wedged and lateralized nucleus pulposus partially reduced to a more symmetrical position. Conclusion: Simple extension of the scoliotic spine leads to a reduction of the deformity in the coronal and axial plane. The shape of the disc normalizes and the eccentric nucleus pulposus partially moves back to the midline.

Introduction: Treatment management of pediatric spinal deformity patients heavily relies on radiological imaging; always with X-rays and sometimes CT scans to better delineate 3D morphology, and increasingly for navigation purposes. It is important to minimize radiation exposure in this vulnerable pediatric population, since it increases the risk for cancer development. This pilot study investigates the feasibility and reliability of 3D-spinal parameters identified on MRI-based quantitative synthetic CTs (sCTs) to assess scoliosis in adolescents. Methods: Ten pre-operative MRI’s from adolescent idiopathic scoliosis patients (mean age: 13.5 years) with curves on standing x-ray > 40° were included. A 4-min 3D spoiled gradient echo MRI sequence capturing the main thoracic curve was added to the clinical sequences and quantitative sCTs were generated. Three independent observers measured Cobb angle, T4-T12 thoracic kyphosis (TK) and apical vertebral rotation (AVR). Interrater reliability and 95% confidence intervals (CI) were calculated. Results: The sCTs clearly visualized the vertebral bodies and posterior elements, allowing for easy landmark identification to assess spinal morphology parameters of individual discs and vertebral bodies. Minor artifacts were observed in intervertebral discs and near the respiratory tract, not affecting the landmark positioning. The interrater reliability ICCs were Cobb angle: 0.99 (95% CI 0.98–1.00), TK: 0.98 (0.95–1.00) and AVR: 0.95 (0.86–0.99). Conclusion: This pilot study confirms that sCT derived from MRI allows for radiation-free and reliable measurement of 3D deformity parameters in AIS patients. While further research is needed, these findings demonstrate the potential for high-quality MRI-based bone imaging and its possible application in AIS treatment planning.

Purpose: The ring apophysis is a secondary ossification center on both sides of each vertebral body, to which the annulus of the intervertebral disc inserts. Recently, its pattern of ossification and fusion to the vertebral body was described for the normal growing spine. The aim of the present study was to investigate the ossification and fusion of the ring apophysis in patients with adolescent idiopathic scoliosis (AIS) and compare it to the normal growing population. Methods: Ring apophysis maturation along the entire thoracic and lumbar spine was analyzed on CT scans of 99 female, pre-operative AIS patients and compared to 134 CT scans of non-scoliotic girls, aged 12 to 20. Results: The ring apophysis maturation in AIS patients was delayed at all spinal levels in AIS patients compared to non-scoliotic controls. Ossification starts at T4–T11 at age 12, followed by T1–T5 and L3–S1 at age 15. The fusion process in AIS patients continues longer in the midthoracic region as compared to the other regions and as compared to non-scoliotic controls, with many incomplete fusions still at age 20. Conclusion: The ring apophysis maturation in AIS is delayed compared to that in the normal population and lasts longer in the mid/low thoracic spine. Delayed maturation of the spine’s most important stabilizer, while the body’s dimensions continue to increase, could be part of the patho-mechanism of AIS.

We would like to thank you for the opportunity to reply to the comments in regard of the letter by Dr. Weiss