Martin Heegaard

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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.

Study design: Retrospective Cohort Study. Objectives: Low bone mineral density (BMD) is a known risk factor for revision surgery in patients with adult spinal deformity (ASD). Hounsfield units (HUs) on CT scans have been suggested as a proxy for assessing BMD. This study aimed to determine HUs in the lumbar region and their association with mechanical failure in patients undergoing ASD surgery. Methods: We included ASD patients undergoing surgery from 2010-2020 with minimum 2-year follow-up. We excluded patients without preoperative CT scans, or a CT scan more than 1 year before surgery. Mechanical failure was defined as proximal junctional failure, pseudarthrosis, or implant failure requiring revision surgery. On preoperative CT scans, HUs were measured on 3 axial slices on each vertebra from L1-L5 and, if available, at UIV and UIV + 1. Results: We included 170 patients, mean age 63 (±12) years, with 108 (64%) females, and 13 [IQR 10-16] instrumented levels. Mechanical failure occurred in 27% (n = 46) of patients at 2-year follow-up. Mean lumbar HUs were 146 (±51) in the mechanical failure group and 135 (±52) in those without revision ( P = .232). Area under the curve was 0.58 (95% CI: 0.48-0.68), corresponding to no to low discriminatory power in predicting mechanical failure using lumbar HUs. Univariate logistic regression revealed no significant difference between mechanical failure and lumbar HUs (OR = 1.00, 95% CI: 1.00-1.01, P = .239). Conclusions: We found no association between mechanical failure and HUs on preoperative CT scans in ASD patients. Thus, we cannot recommend using HUs to predict mechanical failure in these patients.

Study Design.: Retrospective multicenter cohort study. Objective.: To investigate the impact of night-time bracing (NTB) and full-time bracing (FTB) on the sagittal profile in patients with adolescent idiopathic scoliosis (AIS). Background.: Recent studies have shown that FTB in patients with AIS may induce hypokyphosis. Whether this effect differs between NTB and FTB is unknown. Materials and Methods.: We included skeletally immature patients with AIS with main curves ranging from 20° to 45° treated with either NTB or FTB. The 2 cohorts were propensity-score matched on Risser stage, age, major curve size, and kyphosis at brace initiation. Coronal and sagittal radiographic parameters were gathered at the initiation and completion of brace treatment. Results.: Two hundred fifty-seven patients were eligible for inclusion. The matched cohorts included 62 patients in each group. During bracing, the thoracic kyphosis increased from 31 ± 11° to 35 ± 13° in the NTB group compared with a decrease from 30 ± 12° to 28 ± 13° in the FTB group (P = 0.011). Of the total, 8% were hypokyphotic (50° was seen in 50% of the NTB group and 31% in FTB (P = 0.028). Conclusion.: We saw a small increase in thoracic kyphosis in the NTB group versus a small decrease in the FTB group. After bracing, 8% in the NTB group versus 24% in the FTB group showed substantial hypokyphosis. The impact of minor changes in thoracic kyphosis remains uncertain; however, a 3-fold difference in the occurrence of hypokyphosis is notable and merits further attention.

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.

Background and purpose: The efficacy of bracing larger curves in adolescent idiopathic scoliosis (AIS) patients is uncertain. We aimed to assess the influence of night-time bracing in AIS patients with main curves exceeding 40° Cobb angle at brace initiation.Methods: We reviewed AIS patients treated with nighttime braces between 2005 and 2018. Patients with curves ≥ 25° and estimated growth potential were included. Patients were monitored with radiographs from brace initiation until brace weaning at skeletal maturity. Patients were grouped based on curve magnitude at initial evaluation: a control group (25–39°) and a large-curves group (≥ 40°). Progression was defined as > 5° increase.Results: We included 299 patients (control group, n = 125; large-curves group, n = 174). In the control group, 65 (52%) patients progressed compared with 101 (58%) in the large-curves group (P = 0.3). The lower-end vertebra (LEV) shifted distally post-bracing in 41 (23%) patients in the largecurves group. Patients with progressive large curves were younger (age 13.2 [SD 1.5] vs. 13.9 [SD 1.1], P = 0.009) and more premenarchal (n = 36 [42%] vs. n = 6 [9%], P < 0.001) compared with non-progressive large curves.Conclusion: Progression risk in patients with curves exceeding 40° treated with night-time bracing is similar to smaller curves. The LEV moved distally in almost one-fourth of the larger curves, possibly affecting fusion levels in cases of surgery.

Purpose: Risser stage is widely used as a marker for skeletal maturity (SM) and thereby an indirect measure for the risk of progression of adolescent idiopathic scoliosis (AIS). The Scoliosis Research Society recommends bracing for Risser stages 0–2 as Risser stage 3 or above is considered low risk. Very few studies have assessed the risk of progression during bracing in Risser stages 3–4. The objective of the current study is to determine if Risser stages 3–4 provide a meaningful cutoff in terms of progression risk in patients with AIS treated with night-time bracing. Methods: AIS patients treated with night-time brace from 2005 to 2018 with a Cobb angle between 25 and 40 degrees and Risser stages 0–4 were retrospectively included. Curve progression (> 5 degrees increase) was monitored until surgery or SM. Skeletal maturity was defined as either 2 years postmenarchal, no height development or closed ulnar epiphyseal plates on radiographs. Results: One hundred and thirty-five patients were included (Risser stages 0–2: n = 86 and 3–4: n = 49). Overall, radiographic curve progression occurred in 52% while progression beyond 45 degrees was seen in 35%. The progression rate in the Risser 0–2 group was 60% and 37% in the Risser 3–4 group (p = 0.012). In multivariate logistic regression analysis, adjusted for Risser stages and age, only premenarchal status showed a statistically significant association with progression (OR: 2.68, 95%CI 1.08–6.67). Conclusion: Risser stage does not provide a clinically meaningful differentiation of progression risk in AIS patients treated with a night-time brace. Risk assessment should include other more reliable measures of skeletal growth potential.