The effect of Providence night-time bracing on the sagittal profile in adolescent idiopathic scoliosis.

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.

The influence of night-time bracing on curve progression is not affected by curve magnitude in adolescent idiopathic scoliosis: a study of 299 patients.

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.

Does Risser stage accurately predict the risk of curve progression in patients with adolescent idiopathic scoliosis treated with night-time bracing?

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.

The Association Between Hounsfield Units and Mechanical Failure in ASD 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.

The Effect of Night-time versus Full-time Bracing on the Sagittal Profile in Adolescent Idiopathic Scoliosis: A Propensity Score-matched Study.

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 adolescent idiopathic scoliosis (AIS) patients. SUMMARY OF BACKGROUND DATA: Recent studies have shown that FTB in AIS patients may induce hypokyphosis. Whether this effect differs between NTB and FTB is unknown. METHODS: We included skeletally immature AIS patients with main curves ranging from 20-45° treated with either NTB or FTB. The two 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 to a decrease from 30±12° to 28±13° in the FTB group (P=0.011). Eight percent were hypokyphotic (<20°) after bracing in the NTB group compared to 24% in the FTB group (P=0.015). Pelvic incidence, sacral slope, and pelvic tilt were not significantly different between the groups. In the coronal plane, curve progression >50° was seen in 50% in the NTB group and 31% in FTB (P=0.028). CONCLUSION: We saw a small increase in thoracic kyphosis in the NTB group vs. a small decrease in the FTB group. Eight percent in the NTB group vs 24% in the FTB group showed substantial hypokyphosis after bracing. The impact of minor changes in thoracic kyphosis remains uncertain; however, a threefold difference in the occurrence of hypokyphosis is notable and merits further attention.

Demineralized cortical fibers are associated with a low pseudarthrosis rate in patients undergoing surgery for adult spinal deformity without three-column osteotomy.

Introduction: Following surgical treatment for adult spinal deformity (ASD) there is an increased risk of revision surgery due to mechanical failure or pseudarthrosis. Demineralized cortical fibers (DCF) were introduced at our institution aiming to reduce the risk of pseudarthrosis after ASD surgery. Research question: We wanted to investigate the effect of DCF on postoperative pseudarthrosis compared with allogenic bone graft in ASD surgery without three-column osteotomies (3CO). Materials & Methods: All patients undergoing ASD surgery between January 1, 2010 to June 31, 2020 were included in this interventional study with historical controls. Patients with current or previous 3CO were excluded. Before February 1, 2017, patients undergoing surgery received auto- and allogenic bone graft (non-DCF group) whilst patients after received DCF in addition to autologous bone graft (DCF group). Patients were followed for at least two years. The primary outcome was radiographic or CT-verified postoperative pseudarthrosis requiring revision surgery. Results: We included 50 patients in the DCF group and 85 patients in the non-DCF group for final analysis. Pseudarthrosis requiring revision surgery at two-year follow-up occurred in seven (14%) patients in the DCF group compared with 28 (33%) patients in the non-DCF group (p â€‹= â€‹0.016). The difference was statistically significant, corresponding to a relative risk of 0.43 (95%CI: 0.21-0.94) in favor of the DCF group. Conclusion: We assessed the use of DCF in patients undergoing ASD surgery without 3CO. Our results suggest that the use of DCF was associated with a considerable decreased risk of postoperative pseudarthrosis requiring revision surgery.

Complications Following Surgery for Adult Scheuermann's Kyphosis: A 2-Year Follow-Up in 22 Patients.

AIM: To determine the rate of postoperative complications following surgery for Scheuermann?s kyphosis (SK) and ascertain whether restoration to an ideal Roussouly spine type reduced the incidence of postoperative proximal junctional kyphosis (PJK). MATERIAL AND METHODS: We retrospectively screened all patients undergoing SK surgery at our institution (2010?2017) and excluded patients with less than two years of follow-up. Postoperative complications were identified as early or late and minor or major. Successful restoration of Roussouly spine type was assessed and patients were classified as ?restored? or ?non-restored.? Associations between ideal Roussouly restoration and postoperative PJK were evaluated using logistic regression analysis. RESULTS: The study included 22 patients with a median age of 23 (IQR, 20.0?43.8) years. Postoperative complications developed in 17 (77%) of these cases. All 17 patients developed minor complications; seven (32%) patients also exhibited major complications. PJK was diagnosed in 55% of the patients with an 18% overall two-year revision rate. Forty-four percent of the patients in the restored group developed PJK compared to 83% in the non-restored group (p=0.162). Multivariable logistic regression analysis revealed a trend towards an increased incidence of PJK in the non-restored group, albeit without statistical significance (OR, 9.4; 95% CI, 0.7?122.5, p=0.087). CONCLUSION: Our study revealed that 77% of patients undergoing surgery for SK developed at least one complication with a two-year revision rate of 18%. PJK was detected less frequently in patients who were restored to their ideal Roussouly spine type, although this finding did not achieve statistical significance.

Lordosis Distribution Index in Short-Segment Lumbar Spine Fusion - Can Ideal Lordosis Reduce Revision Surgery and Iatrogenic Deformity?

OBJECTIVE: The demand for spinal fusion is increasing, with concurrent reports of iatrogenic adult spinal deformity (flatback deformity) possibly due to inappropriate lordosis distribution. This distribution is assessed using the lordosis distribution index (LDI) which describes the upper and lower arc lordosis ratio. Maldistributed LDI has been associated to adjacent segment disease following interbody fusion, although correlation to later-stage deformity is yet to be assessed. We therefore aimed to investigate if hypolordotic lordosis maldistribution was associated to radiographic deformity-surrogates or revision surgery following instrumented lumbar fusion. METHODS: All patients undergoing fusion surgery ( ≤ 4 vertebra) for degenerative lumbar diseases were retrospectively included at a single center. Patients were categorized according to their postoperative LDI as: "normal" (LDI 50-80), "hypolordotic" (LDI < 50), or "hyperlordotic" (LDI > 80). RESULTS: We included 149 patients who were followed for 21 ± 14 months. Most attained a normally distributed lordosis (62%). The hypolordotic group had increased postoperative pelvic tilt (PT) (p < 0.001), pelvic incidence minus lumbar lordosis (PI-LL) mismatch (p < 0.001) and decreased global lordosis (p = 0.007) compared to the normal group. Survival analyses revealed a significant difference in revision surgery (p = 0.03), and subsequent multivariable logistic regression showed increased odds of 1-year revision in the hypolordotic group (p = 0.04). There was also a negative, linear correlation between preoperative pelvic incidence (PI) and postoperative LDI (p < 0.001). CONCLUSION: In patients undergoing instrumented lumbar fusion surgery, hypolordotic lordosis maldistribution (LDI < 50) was associated to increased risk of revision surgery, increased postoperative PT and PI-LL mismatch. Lordosis distribution should be considered prior to spinal fusion, especially in high PI patients.