Martin Gehrchen

Purpose: To identify predictors for different severities of progression in Adolescent Idiopathic Scoliosis (AIS) patients undergoing night-time brace treatment. Methods: Patients with AIS, prescribed a nighttime brace between 2006 and 2023, with an initial curve angle of 20-45 ^o , and Risser 0–3 were retrospectively included. Patients were grouped by progression: no progression (< 5 ^o ), mild (5-10 ^o ), moderate (11-20 ^o ), or severe (> 20 ^o ). We assessed variables including coronal deformity angular ratio (C-DAR), in-brace correction (IBC%), and curve type. Multinomial logistic regression assessed associations between curve characteristics and progression severity. Progression o was used for reference. An OR of less than 1 indicates lower risk of progression. Results: We included 285 patients with a mean age of 13.3 ± 1.3 years and initial curve size of 36°±7°; 80% of the cohort was female; 68% had thoracic curve types. Younger age was the strongest predictor of progression, differentiating severe and moderate progression from mild cases (OR 0.44 and 0.61). Thoracic curve type was the next influential parameter, associated with severe and mild progression (OR 2.57 and 2.26). Higher initial curve size predicted moderate progression only (OR 1.13). Female sex and higher IBC were protective variables, reducing the odds of mild and severe progression (Female: OR 0.38 and 0.29; IBC: OR 0.96 and 0.98). C-DAR showed no significant association with progression. Conclusion: Male sex, low IBC, and thoracic curve type predicted progression, did not differentiate well between the mild and severe progression. Younger age predicted moderate and severe progression, but not mild. Skeletal maturity remains the crucial consideration for risk assessment.

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Study design: This is a retrospective single-center study. Purpose: The purpose is to investigate the incidence of distal junctional kyphosis (DJK) when fused proximal to the stable sagittal vertebra (SSV) in adolescent idiopathic scoliosis (AIS) patients undergoing selective thoracic fusion. Methods: We retrospectively reviewed a consecutive cohort of surgically treated AIS patients with Lenke 1–2 A/B curves between 2011 and 2022 with a minimum of 2 years of follow-up. The SSV was defined as the vertebra bisected by the posterior sacral vertical line on long-standing sagittal radiographs. All patients underwent posterior pedicle screw instrumentation, and the decision of fusion level was at the surgeons’ discretion. Distal junctional kyphosis was defined as ≥10° angulation between the lower instrumented vertebra (LIV) and the vertebra below the LIV (LIV + 1). Patients were stratified into Fusion proximal of SSV (Prox-SSV) and fusion including SSV (Incl-SSV). Multivariable backward regression was performed to identify predictors for DJK. Results: A total of 196 patients were included, with 80 in the Prox-SSV group. The overall DJK rate was 3.6% (7/196), occurring in 6.3% (5/80) in the Prox-SSV group and 1.7% (2/116) in the Incl-SSV group, respectively ( p = 0.125). Fusion proximal of SSV did not significantly increase DJK risk (Univariate OR 7.98, 95% CI 0.87–66.6; excluded in multivariable regression). Using SSV for LIV selection would extend the fusion by one level in 63.8%, two in 25.0%, and three in 11.2% of patients. Conclusion: The overall risk of DJK is small in thoracic curves and fusion proximal to the SSV did not significantly increase the risk of DJK. Standardized use of SSV as LIV would result in a substantial extension of the fusion area with questionable benefits to the patients.

There is limited knowledge on diffusing capacity in scoliosis patients. It remains to be determined if impaired pulmonary diffusing capacity is mostly influenced by reduced alveolar–capillary membrane diffusing capacity (D_{M, CO}), reduced pulmonary capillary blood volume (V_C) or both. This study aims to report findings from dual test gas pulmonary diffusing capacity for carbon monoxide and nitric oxide (D_{L, CO, NO}) with quantification of pulmonary diffusing capacity for carbon monoxide corrected for haemoglobin with a five s breath‐hold (D_{L, COc, 5s}) and nitric oxide with a five s breath‐hold (D_{L, NO, 5s}), D_{M, CO} and V_C. The study included 57 patients with idiopathic scoliosis seen at our department from 1972 to 1983, all of whom underwent radiological assessment and measurement of D_{L, CO, NO} during examination 40 years after diagnosis. One‐way ANOVA was performed for between‐group differences and Pearson's correlation coefficient was used to assess correlations between D_{L, CO, NO} metrics and Cobb angle. No significant between‐group differences based on disease severity were detected. Thirty‐nine percent of the patients were presented with either reduced D_{L, COc, 5s} or reduced D_{L, NO, 5s} represented as Z‐scores below −1.65. No significant correlations between Cobb angle and Z‐scores for D_{L, COc, 5s}, D_{L, NO, 5s}, D_{M, CO} and V_C according to height measurements were found. When using arm span instead, a weak negative correlation between D_{L, COc, 5s} and Cobb angle (r = −0.29; P = 0.04) was detected. In conclusion, approximately 39% of patients with idiopathic scoliosis had either reduced D_{L, COc, 5s} or reduced D_{L, NO, 5s} 40 years after diagnosis with varying contributions from V_C or D_{M, CO}.

Purpose To investigate the relationship between spinal cord anatomy and the risk of curve progression in mild to moderate adolescent idiopathic scoliosis (AIS). Methods We prospectively included patients presenting with mild or moderate AIS (< 40 degrees). Irrespective of curve severity, patients underwent 3-dimensional MRI and were followed until skeletal maturity or surgery. Retrospectively, we measured the true lateral cord space (LCS) ratio on transverse cuts of the curve apex. This is a measure of the lateral displacement of the medulla in the spinal canal. The primary outcome measure was curve progression defined as a Cobb angle increase ≥ 10 degrees at follow-up. Results Of the 64 included patients, 18 (28%) progressed more than 10 degrees during follow-up. At baseline, mean age in the progression and non-progression group was 13.1 ± 1.6 vs. 15.8 ± 1.5 years (p < 0.001), and mean Cobb angle was 32 ± 7 vs. 26 ± 9 degrees (p < 0.001). The time from baseline x-ray to MRI was 1.3 ± 3 months vs. 1.7 ± 3.6 months (p = 0.738). LCS ratio was 1.5 (IQR: 1.1–1.7) in the progression group and 1.0 (IQR:0.8–1.3) in the non-progression group (p < 0.001). When matched according to baseline Cobb angle and age, median LCS ratio was 1.5 [1.1, 1.7] and 0.9 [0.7–1.2] in the progression and non-progression group, respectively (p < 0.001). Conclusions We found significant displacement of the medulla towards the concavity of the curve in progressive AIS. This finding supports the theory of a neuro-osseous growth mismatch as a part of the etiopathophysiology of AIS and may play a predictive role in prognosis of milder cases of AIS.

Purpose: To examine if coronal deformity angular ratio (C-DAR) serves as a predictor for progression to surgical magnitude in patients with Adolescent Idiopathic Scoliosis (AIS) treated with thoracolumbar sacral orthosis (TLSO). Methods: Patients with AIS, prescribed a full-time TLSO, Cobb angle 20–40°, Risser 0–2, who wore the brace ≥ 12.9 h and reached skeletal maturity/surgery were included retrospectively. C-DAR was defined as the Cobb angle divided by the number of vertebrae in the curve, yielding a larger value in short curves. The association between C-DAR and the risk of progression to surgical magnitude (> 45°) was assessed. Secondly, we evaluated the association between pre-treatment Cobb angle and in-brace correction on the risk of progression to > 45°. Results: We included 165 patients with a mean Cobb angle of 30 ± 6°. Of these, 46/165 (28%) progressed ≥ 6° and 26/165 (16%) reached surgical magnitude at the end of treatment. C-DAR was a significant predictor for risk of progression to surgical magnitude with an OR of 1.9 (CI 1.2–2.9) per unit increase in C-DAR. A threshold value of 5.15 was established and demonstrated an OR 5.9 (CI 2.1–17.9) for curve progression to a surgical magnitude. Likewise, pre-treatment Cobb angle showed a significant OR 1.3(CI 1.2–1.4) per degree increase in Cobb, whereas in-brace % correction showed OR 0.96 (CI 0.93–0.98). Conclusion: C-DAR is an independent predictor for progression to a surgical magnitude in AIS patients treated with bracing. Patients with a higher C-DAR should be counseled to help set realistic expectations regarding the likelihood of curve progression despite compliance with brace wear.

Purpose: Adolescent idiopathic scoliosis (AIS) is characterized by coronal scoliosis and often a sagittal hypokyphosis. The effect of bracing on the sagittal profile is not well understood. The aim of this study is to assess the effect of night-time bracing on the sagittal profile in patients with AIS. Methods: We retrospectively included AIS patients with a main curve of 25–45° treated with a night-time brace in our institution between 2005 and 2018. Patients with estimated growth potential based on either Risser stage, hand X-rays, or menarchal status were included. Coronal and sagittal radiographic parameters were recorded at both brace- initiation and -termination. Patients were followed until surgery or one year after brace termination. Results were compared to a published cohort of full-time braced patients. Results: One hundred forty-six patients were included. Maximum thoracic kyphosis (TK) increased 2.5° (± 9.7) (p = 0.003), corresponding to a 3.5-fold relative risk increase post bracing in TK compared to a full-time brace cohort. Twenty-seven percent (n = 36) of the patients were hypokyphotic (T4/T12 < 20°) at brace initiation compared with 19% (n = 26) at brace termination (p = 0.134). All other sagittal parameters remained the same at follow-up. We found no association between progression in the coronal plane and change in sagittal parameters. Conclusion: This is the first study to indicate that night-time bracing of AIS does not induce hypokyphosis. We found a small increase in TK, with a substantially lower risk of developing flat back deformity compared to full-time bracing. The coronal curve progression was not coupled to a change in TK.

Recently carbon spinal implants have been introduced in the treatment of patients with metastatic spinal cord compression (MSCC). This is expected to decrease the deflection of radiation and improve diagnostic imaging and radiotherapy when compared to titanium implants. The aim of this study was to determine the safety and effectiveness of spinal carbon instrumentation (CI) in patients with MSCC in a large cohort study. A total of 163 patients received instrumentation between 1 January 2017 and 31 December 2021. A total of 80 were stabilized with CI and 83 with TI. The outcome measures were surgical revision, postsurgical survival, peri-operative bleeding, and surgery time. The peri-operative blood loss in the CI-group was significantly lower than that in the TI-group: 450mL vs. 630mL, (p = 0.02). There were no significant differences between the groups in mean survival (CI 9.9) vs. (TI 12.9) months (p = 0.39), or the number of patients needing a revision (CI 6) vs. (TI 10), (p = 0.39). The median duration of surgery was 121 min, (p = 0.99) with no significant difference between the two groups. Surgical treatment with CI for MSCC is safe and an equally sufficient treatment when compared to TI.