Main Thoracic Curve Research Articles

Reducing the Brace Correction Stress on the Secondary Lumbar Curve Results in Excellent Muscle, Bone, and Disc Mechanical Performance: A Musculoskeletal Finite Element Simulation of AIS Patient With Rigo A3.

The biomechanical mechanism of brace intervention on bone, muscle, and disc should be comprehensively considered for AIS patients. We aimed to developmentally construct a musculoskeletal finite element model of adolescent idiopathic scoliosis to simulate the coupling of corrective forces and analyze the mechanical properties of bone, muscle, and disc. Investigateing, more effective clinical interventions to break the vicious cycle of patients during growth. A finite element model, including muscle, bone, and disc, was established using computed tomography data of a patient with RigoA3 adolescent idiopathic scoliosis. The three-point force coupling, antigravity, and bending effects of the Chêneau brace were simulated, and the correction force of the secondary lumbar bend was gradually reduced while observing the mechanical characteristics of bone, muscle, and disc. The correction force in line with symmetrical spine growth was comprehensively evaluated. The correction rate of the main thoracic (MT) curve, the intervertebral space height on the concave side of the vertebrae at the apex, and the stress ratio of the intervertebral discs were optimal when the maximum corrective pressure threshold was reached. However, the proximal thoracic (PT) curve was aggravated and the axial forces on the concave side were unbalanced. At this time, the biomechanical performance of the model is also not optimal. The correction rate of the Cobb Angle of the MT curve decreased with the decrease of the correction pressure in the lumbar region. When reduced to 25% of the maximum threshold, the convex side of disc stress, intervertebral space, and muscle axial force is more in line with the biomechanical mechanism of correction and can avoid sacrificing the PT curve. Downward adjustment of the corrective force to the secondary lumbar curve, using the Chêneau brace, results in better primary thoracic curvature mechanics in the musculoskeletal finite element model, suggesting that breaking the vicious cycle of scoliosis progression to guide benign spinal growth is beneficial.

Construction and Validation of a Nomogram for Predicting the Adding-on Phenomenon Postoperatively for Adolescent Idiopathic Scoliosis: A Retrospective Study

To develop and validate a nomogram predicting the postoperative adding-on (AO) phenomenon in Lenke 1/2 adolescent idiopathic scoliosis (AIS) patients, providing a quantitative tool for therapeutic benefit assessment and personalized risk prediction. A retrospective analysis was conducted using clinical data from 213 patients. The least absolute shrinkage selection operator (Lasso) was applied to identify the best predictors. Multivariate logistic regression was used to construct a nomogram with a training set (80%), while a validation set (20%) was used for internal validation. The receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) assessed the model's clinical utility. The model was constructed using the four best predictor variables: the number of vertebrae in the main thoracic curve (NV-MTC), apical vertebra translation (AVT), last instrumented vertebra rotation (LIVR), and Risser sign (RS). The model's C-index was 0.932 (95% confidence interval, 0.8858-0.9775). DCA indicated a clinically meaningful high-risk threshold between 0 and 1, and the calibration curve demonstrated satisfactory accuracy. The model proved useful for predicting the occurrence of AO in Lenke 1/2 AIS patients after surgery.

Risk Factors for Postoperative Shoulder Imbalance in Patients with Lenke Type 1 and 2 Scoliosis Treated using the Vertebral Coplanar Alignment Technique.

This was a multicenter retrospective cohort study. We investigated the incidence of postoperative shoulder imbalance (PSI) and its risk factors in patients with Lenke types 1 and 2 scoliosis corrected using vertebral coplanar alignment (VCA). PSI in scoliosis affects patient quality of life. While other correction methods have reported a high correction rate for the main thoracic curve (MTC) in relation to PSI, this correlation has not been confirmed for the VCA technique. We studied 176 patients with Lenke types 1 and 2 scoliosis who underwent posterior corrective fusion surgery using the VCA technique at 11 institutions. At two years postoperatively, patients were divided into two groups based on radiographic shoulder height (RSH): PSI- (RSH<2cm) and PSI+ (RSH≧2cm) groups. We analyzed the risk factors for PSI. The overall incidence of PSI two years postoperatively was 11.4% (20/176), with 9.2% (11/119) and 15.8% (9/57) in patients with Lenke types 1 and 2, respectively. Contrary to a previous study, a high MTC correction rate did not emerge as a risk factor for PSI. Instead, preoperative left shoulder elevation and low postoperative thoracic kyphosis and greater T1 tilt and high apical vertebral body-to-rib ratio were associated with PSI in patients with Lenke type 1. Preoperative left shoulder elevation and a low postoperative proximal thoracic curve (PTC) correction rate were identified as risk factors for PSI in patients with Lenke type 2. Our results suggest that proper correction of the PTC, rather than compromise MTC correction, may help prevent PSI in the VCA technique. This method is particularly advantageous for addressing Lenke type 1 scoliosis and yields favorable outcomes in shoulder balance. Patients with preoperative left shoulder elevation, especially Lenke type 2, are at high risk of developing PSI. 4.

Vertebral Body Tethering for Thoracolumbar Curvatures in Adolescent Idiopathic Scoliosis: Radiographic and Clinical Outcomes at 2-6-Year Follow-Up.

Background: The gold standard treatment for adolescent idiopathic scoliosis (AIS) is posterior spinal fusion (PSF). However, long-term consequences of PSF can include reduced spinal flexibility, back pain, and intervertebral disc degeneration. Vertebral body tethering (VBT) is a non-fusion alternative that preserves motion. We investigated the outcomes of VBT for the treatment of thoracolumbar (TL) major AIS in the largest single-surgeon series with a minimum 2-year follow-up (FU). Methods: We performed a retrospective single-center review. Inclusion criteria were AIS, Lenke 5/6 curvature, and skeletally immature Variables were compared using Student's t-tests, Wilcoxon rank sum tests, Chi-square, and Fisher's exact tests. Results: A total of 37 consecutive patients, age 14.1 ± 1.6 years, 86.5% F, 35.9 ± 11.5-month FU, were examined. Overall, 27 patients (73%) had Lenke 5 and 10 (27%) had Lenke 6 curvatures. Instrumentation of the TL curve alone was performed in 59.5%, and thoracic (T) and TL in 40.5% of patients. Overall, 45.9% of patients had two tethers placed in the TL spine; no patients had double tethers placed at the main thoracic curves. The TL (51 ± 8° to 20 ± 11°; p < 0.0001) and T (37 ± 13° to 17 ± 10°; p < 0.0001) curvatures improved from baseline to the latest FU. Overall, 89% of patients achieved major Cobb < 35°; the three patients who did not experienced at least one cord breakage or required PSF. T5-T12 kyphosis increased (p = 0.0401) and lumbar lordosis was maintained (p = 0.9236). Both the TL inclinometer (16 ± 4º to 4 ± 2°; p < 0.0001) and T (6 ± 4° to 4 ± 3°; p = 0.0036) measurements improved. There was a 49% tether breakage rate as follows: 60% for single-cord TL constructs and 35% for double cords (p = 0.0991). There was an 8.1% re-operation rate as follows: one conversion to T PSF and revision of the TL tether; one release of the T tether and revision of the TL tether; one screw revision for radiculopathy. One patient was re-admitted for poor pain control. Conclusions: Patients with TL major curvature treated with VBT experienced a high rate of clinically successful outcomes with maintenance of lumbar lordosis and relatively low complication rates at the latest FU.

Immediate Correction of Idiopathic Scoliosis With Nighttime Braces Created by a Fully Automated Generative Design Algorithm: A Randomized Controlled Crossover Trial.

Single-center, double-blinded, prospective crossover randomized controlled trial. To clinically validate the efficacy of nighttime braces designed automatically by a generative design algorithm to treat idiopathic scoliosis (IS). The tested hypothesis was the clinical equivalence of immediate in-brace correction for the new automatically generated brace design versus a standard Providence-type brace. Documented efficacy of brace treatment varies between centers, and depends on the empirical expertise of the treating orthotist. Our group previously developed a fully automated generative brace design algorithm that leverages a patient-specific finite-element model (FEM) to optimize brace geometry and correction before its fabrication. Fifty-eight skeletally immature patients diagnosed with IS, aged between 10 and 16 years were recruited. All patients received both a nighttime brace automatically generated by the algorithm (test) and a Providence-type brace designed by an expert orthotist (control). Radiographs were taken for each patient with both braces in a randomized crossover approach to evaluate immediate in-brace correction. The targeted 55 patients (48 females, 7 males) completed the study. The immediate Cobb angle correction was 57% 19 (test) versus 58% 21 (control) for the main thoracic (MT) curve, whereas it was 89% 25 (test) versus 87% 28 (control) for the thoracolumbar/lumbar (TLL) spine. The immediate correction with the test brace was noninferior to that of the Control brace ( P 0.001). The order in which the braces were tested did not have a residual effect on the immediate correction. The fully automated generative brace design algorithm proves to be clinically relevant, allowing for immediate in-brace correction equivalent to that of braces designed by expert orthotists. Patient 2 years follow-up will continue. This method's integration could help design and rationalize the design of braces for the treatment of IS. Level 2.

Biomechanical study of spinal cord and nerve root in idiopathic scoliosis: based on finite element analysis

BackgroundCurrent research lacks comprehensive investigation into the biomechanical changes in the spinal cord and nerve roots during scoliosis correction. This study employs finite element analysis to extensively explore these biomechanical variations across different Cobb angles, providing valuable insights for clinical treatment.MethodsA personalized finite element model, incorporating vertebrae, ligaments, spinal cord, and nerve roots, was constructed using engineering software. Forces and displacements were applied to achieve Cobb angle improvements, designating T1/2-T4/5 as the upper segment, T5/6-T8/9 as the middle segment, and T9/10-L1/2 as the lower segment. Simulations under traction, pushing, and traction + torsion conditions were conducted, and biomechanical changes in each spinal cord segment and nerve roots were analyzed.ResultsThroughout the scoliosis correction process, the middle spinal cord segment consistently exhibited a risk of injury under various conditions and displacements. The lower spinal cord segment showed no significant injury changes under traction + torsion conditions. In the early correction phase, the upper spinal cord segment demonstrated a risk of injury under all conditions, and the lower spinal cord segment presented a risk of injury under pushing conditions. Traction conditions posed a risk of nerve injury on both sides in the middle and lower segments. Under pushing conditions, there was a risk of nerve injury on both sides in all segments. Traction + torsion conditions implicated a risk of injury to the right nerves in the upper segment, both sides in the middle segment, and the left side in the lower segment. In the later correction stage, there was a risk of injury to the upper spinal cord segment under traction + torsion conditions, the left nerves in the middle segment under traction conditions, and the right nerves in the upper segment under pushing conditions.ConclusionWhen the correction rate reaches 61–68%, particular attention should be given to the upper-mid spinal cord. Pushing conditions also warrant attention to the lower spinal cord and the nerve roots on both sides of the main thoracic curve. Traction conditions require attention to nerve roots bilaterally in the middle and lower segments, while traction combined with torsion conditions necessitate focus on the right-side nerve roots in the upper segment, both sides in the middle segment, and the left-side nerve roots in the lower segment.

Analysis of odontoid parameters in adolescent idiopathic scoliosis patients with different curve types.

Odontoid incidence (OI) is an important parameter that has recently been developed. However, there are currently no studies on OI in adolescent idiopathic scoliosis (AIS) patients. We aimed to examine the significance of OI in describing cervical sagittal alignment in AIS patients, explore the differences in cervical sagittal parameters among these patients with different curve types, and investigate the correlations between coronal deformity and cervical sagittal parameters in AIS patients. The whole-spine anteroposterior and lateral plain radiographs of AIS patients were retrospectively analyzed. The parameters, including OI, odontoid tilt (OT), C2 slope, cervical lordosis (CL), T1 slope (T1S), and others, were measured. The AIS patients were grouped based on different curve types. Measurement parameters were compared between different groups. Pearson correlation analysis was performed for cervical sagittal parameters and Cobb angle. Ninety AIS patients were included, consisting of 14 males and 76 females. The main thoracic curve group exhibited a smaller OI compared to the main thoracolumbar/lumbar curve group (P < 0.05). In the AIS patients with a main thoracic curve, there was a significant correlation between Cobb angle and OI (r = -0.371, p < 0.01). The odontoid parameters exhibited significant correlations with several classic cervical sagittal parameters in AIS patients with different curve types. The validation of the formula CL = 0.36 × OI-0.67 × OT-0.69 × T1S showed a significant correlation (correlation coefficient = 0.917) between the actual measurements and the predicted values, with a determination coefficient of 0.842. There may be a difference in OI between AIS patients with a main thoracic curve and those with a main thoracolumbar/lumbar curve. Odontoid parameters could be used to describe cervical sagittal alignment in AIS patients with different curve types.

Risk of coronal imbalance after posterior surgery for adolescent idiopathic scoliosis of type Lenke5C

Purpose To investigate the incidence, risk factors, and clinical impact of persistent coronal imbalance (PCI) in Lenke5C adolescent idiopathic scoliosis (AIS) undergoing posterior spinal fusion (PSF). Methods We analyzed the medical records of 112 Lenke5C AIS patients. They were grouped into PCI (+) group and PCI (–) group according to the occurrence of PCI at 2 years after surgery. Coronal and sagittal parameters were measured and compared between both groups preoperatively, immediately postoperatively, and 2 years postoperatively. Scoliosis Research Society-22 (SRS-22) score was used to evaluate clinical outcomes. Results Of the 112 patients, 12 had coronal imbalance persisting 2 years after surgery. Logistic regression analysis indicated risk factors including older age [odds ratio (OR) = 1.841, 95% confidence interval (CI) = 1.147–2.132, p = .001], lower preoperative flexibility main thoracic (MT) curve (OR = 1.308, 95% CI = 1.041–2.015, p = .016), greater preoperative apical vertebral translation (AVT) of the thoracolumbar/lumbar (TL/L) curve (AVT-TL/L) (OR = 2.291, 95% CI = 1.120–4.719, p = .001), larger preoperative lowest instrumented vertebra tilt (LIV lilt) (OR = 2.141, 95% CI = 1.491–3.651, p = .011), and postoperative immediate coronal imbalance (OR = 5.512, 95% CI = 4.531–6.891, p = .001). The satisfaction and total score of the SRS-22 scale in the PCI (+) group were lower than those in the PCI (–) group at 2 years after surgery (p <.05). Conclusions We found a 10.7% incidence of PCI in patients with Lenke5C AIS undergoing PSF. PCI adversely affects clinical outcomes. Risk factors of PCI included older age, reduced preoperative MT curve flexibility, increased preoperative AVT in the TL/L curve, greater preoperative LIV tilt, and immediate postoperative coronal imbalance.

Pulmonary function in patients with idiopathic scoliosis 40 years after diagnosis

BACKGROUND CONTEXTPulmonary function in patients with scoliosis has been a topic of concern, with some reports of markedly decreased ventilatory function leading to disability and increased mortality in patients with severe scoliosis. Only limited data is available concerning pulmonary function in adult patients with scoliosis. PURPOSETo report the long-term pulmonary function (PF) in patients diagnosed with idiopathic scoliosis (IS) compared with an age-matched population using extended pulmonary function testing (EPFT). STUDY DESIGN/SETTINGRetrospective clinical follow-up. PATIENT SAMPLEA total of 177 patients seen at our institution from 1972 to 1983 for a pediatric spinal deformity were assessed for inclusion in the study. About 77/129 eligible patients with IS (60%) partook in a clinical examination including radiographs, and EPFT. OUTCOME MEASURESThe EPFT values included forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio, vital capacity (VC), total lung capacity (TLC), residual volume (RV), RV/TLC ratio, diffusion capacity of carbon monoxide (DLco), carbon monoxide transfer coefficient (KCO) and alveolar volume (VA). Results were expressed with z-scores derived from height and arm span normative data. Z-scores were calculated as z-score=Measured PF-Predicted PF /Relative standard deviation (RSD). The limits of normal, are defined as the 5th and 95th percentile limits (z-score between −1.645 and 1.645), respectively. METHODSPatients underwent a clinical examination with full spine standing radiographs and EFPT. The results were compared between patients with thoracic and thoracolumbar/lumbar (TL/L) main curves, and overall compared with a background population. Results were expressed with z-scores derived from height and arm span normative data. RESULTSOf 77 included patients, 76 (99%) were females with a mean age of 54.6±2.5 years. The mean follow-up time was 40.8±2.8 years. Forty-four patients had thoracic main curves, and 33 had TL/L main curves. We found no pulmonary impairment based on z-scores in the total cohort or between groups, with only patients who were current or previous smokers, having z-scores below the normal limits Patients with main thoracic curves displayed significantly lower PF on mean absolute values and mean z-scores on FEV1, FVC, FEV1/FVC ratio, VC, TLC, and DLco compared with main TL/L curves. Patients with thoracic curves had significantly larger Cobb angles at follow-up; 52±17° compared with 40±22° (p-value <.05) in the TL/L group. We found no linear association between thoracic Cobb angle and degree of pulmonary impairment assessed with DLco, TLC, and FVC. Comparison of pulmonary z-scores based on arm span data, differed significantly on FVC and TLC, with the arm span measurements showing lower mean z-scores (p-value <.05). CONCLUSIONSUsing EPFT, no pulmonary impairment could be demonstrated compared to the age-matched population 40 years after a diagnosis of IS. However, patients with thoracic curves had decreased PF compared to patients with TL/L curves although within the normal range. Thus, when treated as current guidelines suggest, patients with idiopathic scoliosis can expect the same long-term pulmonary function as the general population.

A Novel Deformity Correction Manipulation System for Better Correction of Large Thoracic Scoliosis.

Treating patients with large thoracic scoliosis (between 70° and 100°) poses technical challenges, particularly with traditional correction techniques (TCT). To address this, we developed a novel deformity correction manipulation system (DCMS) aimed at reducing surgical complexity and trauma. This study aims to assess the safety and effectiveness of DCMS in treating large thoracic scoliosis. From January 2016 to June 2021, 76 patients with large thoracic scoliosis were included in this retrospective study. The patients were divided into two groups: DCMS (n = 34) and TCT (n = 42). Basic patient data including age at surgery, sex, etiology, Risser sign, flexibility of the main thoracic curve, instrumented levels, number of screws, duration of hospital stay, and follow-up time were collected and analyzed. Radiographic and clinical outcomes, as measured by various radiographic parameters and Scoliosis Research Society-30 (SRS-30) scores, were retrospectively analyzed and compared between the two groups. Adverse events were also documented. Statistical analyses were performed using two-tailed independent t-tests, chi-square tests, and Fisher's exact test. The DCMS group exhibited significantly shorter operative times, reduced blood loss, and shorter hospital stays compared to the TCT group. However, there were no significant differences between the two groups in terms of age at surgery, sex, etiology, Risser sign, flexibility of the main curve, instrumented levels, number of screws, and follow-up time. While preoperative major curves were statistically similar between the two groups, the DCMS group achieved a superior correction rate compared to the TCT group (74.2% ± 8.8% vs 68.1% ± 10.5%). No significant differences were observed in other radiographic parameters, SRS-30 scores, or the incidence of adverse events. The application of DCMS resulted in shorter operative times, reduced blood loss, shorter hospital stays, and greater curve correction compared to TCT. DCMS proves to be a safe and effective technique for treating large thoracic curves.

Does levelling of T1 tilt intra-operatively affect post-operative shoulder balancein adolescent idiopathic scoliosis patients?

Previous studies have shown that T1 tilt is positively correlated with post-operative shoulder balance (SB). The aim of this study was to explore the role of intra-operative T1 tilt, among other shoulder parameters as a potential parameter to predict post-operative SB in adolescent idiopathic scoliosis (AIS) patients. A retrospective review of AIS patients with structural thoracic curves with minimum 2year follow up was conducted from a single tertiary center. Standing pre-operative, 1st erect, 1year and 2-year follow-up; and intra-operative final prone radiographs were reviewed along with clinical data. Patients were stratified into 2 cohorts: Group A-Final intra-operative T1 tilt ≤5° and Group B-Final intra-operative T1 tilt >5°. These groups were compared for post-operative SB as a whole and separately for patients with baseline right or left shoulder high and if UIV was T2 or T3/T4. Patients with optimal SB (Radiographic shoulder height (RSH) <2cm) at 2years were compared to sub-optimal SB (RSH ≥ 2cm) with respect to multiple SB variables. 55 patients (mean age 15.1years-old, 43 F, mean BMI 22, mean thoracic Cobb-49.8°) were included. Based on Lenke curve types, there were 13 patients with type 1A, 10 patients with 1B, 12 patients with 1C, 7 patients with 2A, 4 patients with 2B and 9 patients with type 3C. T1 tilt was significantly correlated with RSH, Clavicle angle difference (CAD), First Rib Angle (FRA), and UIV tilt at first erect, 1-year, and 2-year post-op radiographs (p < 0.05 for all). When comparing groups, A and B, Group A patients showed significantly better restoration of their 2-year SB parameters; RSH (6.8 vs 11.8mm, p = 0.01), CAD (3.9 vs 9.1 p < 0.001) and T1 tilt (4.7 vs 7.8° p = 0.01). Similar results were found for patients with baseline right shoulder high; RSH (p = 0.04), CAD (p < 0.001) and T1 tilt (p < 0.001) and whether UIV was T2 or T3/T4. Eight patients with sub-optimal SB had worse intra-operative T1 tilt (p = 0.03) compared to 47 patients with optimal SB despite no difference in MT Cobb correction (83.1 vs 79.8%, p = 0.57). Post-operative T1 tilt correlates with lateral shoulder parameters at first erect, 1year, and 2-year radiographs. Therefore, T1 tilt can potentially be used as a surrogate to predict post-operative SB. Leveling intra-operative T1 tilt ≤5° is associated with better 2-year post-operative shoulder balance parameters irrespective of whether the UIV was T2 or T3/T4. Patients with sub-optimal SB at 2years had worse final intra-operative T1 tilt despite similar percent correction of main thoracic curve for all patients.

Severe (>100 Degrees) Thoracic Adolescent Idiopathic Scoliosis - A Comparison of Surgical Approaches.

Retrospective. Severe curves >100° in adolescent idiopathic scoliosis (AIS) are rare and require careful operative planning. The aim of this study was to assess baseline, perioperative, and 2-year differences between anterior release with posterior instrumentation (AP), posterior instrumentation with posterior column osteotomies (P), and posterior instrumentation with 3-column vertebral osteotomies (VCR). Two scoliosis datasets were queried for primary cases of severe thoracic AIS (≥100°) with 2-year follow-up. Pre- and 2-year postoperative radiographic measures (2D and estimated 3D kyphosis), clinical measurements, and SRS-22 outcomes were compared between three approaches. Sixty-one patients were included: 16 AP (26%), 38 P (62%), 7 VCR (11%). Average age was 14.4 ± 2.0 years; 75.4% were female. Preoperative thoracic curve magnitude (AP: 112°, P: 115°, VCR: 126°, P = 0.09) and T5-T12 kyphosis (AP: 38°, P: 59°, VCR: 70°, P = 0.057) were similar between groups. Estimated 3D kyphosis was less in AP vs P (-12° vs 4°, P = 0.016). Main thoracic curves corrected to 36° in AP vs 49° and 48° for P and VCR, respectively (P = 0.02). Change in estimated 3D kyphosis was greater in AP vs P and VCR (34° vs 13°, P = 0.009; 34° vs 7°, P = 0.046). One incomplete spinal cord injury had residual deficits (P; 1/61, 1.6%). All SRS-22 domains improved postoperatively. All approaches obtained satisfactory coronal and sagittal correction, but AP had smaller residual coronal deformity and greater kyphosis restoration than the other approaches. This information may help inform the decision of whether to include an anterior release for large thoracic AIS curves.

The Evolution of Curve Patterns in Adolescent Idiopathic Scoliosis during Chêneau Brace Treatment.

This retrospective study analyzed bracing outcomes in AIS patients, focusing on curve pattern changes and brace efficacy. To analyze the effectiveness of the Chêneau brace across different curve patterns and to evaluate the tendencies in curve evolution during treatment. Adolescent idiopathic scoliosis (AIS) presents diverse curve patterns, each responding differently to bracing. Understanding these variations is crucial for optimizing treatment strategies. The study included 177 AIS patients treated with Chêneau orthoses, categorized based on curve patterns as per the main curve and modified Lenke (mLenke) classifications. We compared patients according to curve patterns and assessed changes in curve magnitude and pattern before and after treatment. Over an average follow-up of 28.1±10.7 months, the primary curve magnitude decreased from 28.8±6.6° to 25.9±10.5°. Significant reductions were observed in mLenke V and VI patients (P<0.05). Patients with main lumbar curves showed better initial in-brace correction and curve control compared with those with main thoracic curves (P<0.05). In single-curve patterns, binary logistic regression indicated that mLenke V patients demonstrated higher rates of curve control compared with mLenke I patients (P<0.05). No significant differences were found in double-curve patterns between mLenke III and VI (P>0.05). At the final follow-up, thoracolumbar/lumbar curves improved significantly in mLenke III and VI patients (P<0.05), while thoracic curves did not (P>0.05). Furthermore, at the last follow-up, the proportions of mLenke I, II, and IV increased, while mLenke III, V, and VI decreased. Bracing outcomes were more favorable in patients with main lumbar curves than those with main thoracic curves. However, no significant differences were found in patients with double-curve patterns. Thoracic curves exhibited a higher progression risk compared with thoracolumbar/lumbar curves within the same curve pattern. During bracing, a tendency for primary curves to shift proximally was noted.

A novel approach to surgical treatment of adolescent idiopathic scoliosis in skeletally immature patients

PurposeDescribe the surgical technique and experience using the LSZ growing system in skeletally immature patients for two–stage surgical treatment of adolescent idiopathic scoliosis (AIS). MethodsEleven skeletally immature patients who underwent two-stage surgical treatment of AIS in our center were retrospectively analyzed. Patients initially treated with the LSZ growing system were observed for an average of 40.5 months (range 23–64 months) and for 4 years after planned replacement of the LSZ growing system with a standard pedicle screw system. ResultsThe average preoperative angle of the main thoracic curve was 64.55 ± 3.21°, and that of the lumbar curve was 46 ± 5.52°. After instrumentation using the LSZ growing system, the thoracic curve was corrected to 17.63 ± 5.14°, and the lumbar curve to 9.2 ± 5.45°. The correction percentages were 72.52 ± 8.35 and 80.59 ± 10.77, respectively. After planned replacement of the LSZ system with a pedicle screw system, the angle of the thoracic curve changed to 11.45 ± 4.84°, and the lumbar curve to 6.4 ± 4.72°. The percentages of final correction were 82,1 ± 7,91 and 85,64 ± 5,47, respectively. The difference in the “LSZ growth coefficient” was 0.063 ± 0.037, which indicates continued growth of the spine along the instrumented region. None of the patients had neurological or infectious complications. ConclusionOur study demonstrates the safety and effectiveness of 2-stage treatment of AIS using the LSZ system, which allows for spine growth during the period between stages.

Pedicle Dysplasia in Proximal Thoracic Adolescent Idiopathic Scoliosis Curves: What are We Missing and What are its Possible Surgical Implications? An Observational Retrospective Study on 104 Patients.

Retrospective cohort study. To assess if pedicle dysplasia is present in proximal thoracic (PT), both structural and nonstructural, compared to main thoracic (MT) curves; and to assess if it is predictive of radiographic outcomes at minimum 2years of follow-up. A retrospective review of surgically-treated Adolescent Idiopathic Scoliosis (AIS) patients with Lenke 1-2-3-4 curves was performed. On preoperative CT-scan, at the apical vertebra, pedicle width on the concavity (PWc) and on the convexity (PWv) and Pedicle Dysplasia Index (PDI, defined as PWc/PWv) were measured. Preoperative and last follow-up (at least 2years) x-rays were reviewed. 104 patients meeting the inclusion criteria were divided into Structural-PT (S-PT) and Nonstructural-PT (NS-PT) groups based on Lenke criteria. PWc (P < .001). And PDI (P < .001 for S-PT, P = .004 for NS-PT) were significantly smaller in the PT than in MT curves for both groups. PT-PWc significantly correlated with follow-up PT Cobb for both groups (P < .001 and P = .015 respectively). PT-PDI significantly correlated with follow-up PT-Cobb (P < .001), CA (P < .040) and T1 tilt (P < .002), only for NS-PT group. NS-PT patients with PWc PT <1mm had higher RSHD (P = .021) and T1 tilt (P = .025) at follow-up. NS-PT patients with PDI PT <.3 had higher RSHD (P < .001), CA (P = .002) and T1 tilt (P = .003) at follow-up. S-PT and NS-PT curves show significant pedicle dysplasia on the concavity. Pedicle dysplasia significantly correlated with shoulder balance at follow-up, for NS-PT patterns. Patients with a PWc <1mm or PDI <.30 are at particular risk of postoperative shoulder imbalance.

Does Sacral Slanting Affect Postoperative Shoulder Balance in Patients With Lenke Type 2A Adolescent Idiopathic Scoliosis?

Even minor sacral slanting can influence T1 tilt and shoulder balance. Yet, the relationship between sacral slanting and postoperative shoulder imbalance (PSI) has not been previously explored. To determine risk factors for PSI in Lenke 2A adolescent idiopathic scoliosis (AIS) patients, with an emphasis on sacral slanting. The study encompassed 96 consecutive patients who had undergone posterior correction and fusion surgery for Lenke type 2A AIS. Patients were grouped into PSI(+) and PSI(-) based on postoperative outcomes. Additionally, they were classified into left-sided slanting, no slanting, and right-sided slanting groups according to the degree of sacral slanting. Various radiological measures were compared. Patients in the PSI(+) group exhibited a smaller preoperative proximal thoracic curve and a higher main thoracic curve correction rate than those in the PSI(-) group. The presence or absence of sacral slanting did not exhibit a significant variation in PSI occurrence. However, the right-sided sacral slanting group showed a larger delta radiologic shoulder height compared to the other 2 groups (7.1 mm vs. 1.5 & 3.3 mm). Sacral slanting was not directly linked to the development of PSI. Despite the common postoperative elevation of the left shoulder, the shoulder height differences decreased over the follow-up period. Especially in cases with a right-sided tilted sacrum, the PSI demonstrated progressive improvement, with an associated increase in the rightward distal wedging angle, leading to distal adding-on.

The Comparison of Posterior Intervertebral Release Combined with Posterior Column Osteotomy and Posterior Column Osteotomy Alone for the Treatment of Moderate-to-Severe Rigid Scoliosis: A Prospective Controlled Study.

There is no consensus on the treatment of moderate-to-severe rigid scoliosis. Anterior release and three-column osteotomy are excessively traumatic, whereas posterior column osteotomy (PCO) alone results in poor outcomes. An emerging surgical technique, posterior intervertebral release (PR), can release the rigid spine from the posterior approach. This study was performed to compare the multi-segment apical convex PR combined with PCO and PCO alone in patients with moderate-to-severe rigid scoliosis. From June 2021 to June 2022, this prospective study of moderate-to-severe (Cobb: 70-90°) rigid scoliosis (flexibility of main curve <25%) involved two groups defined by surgical procedure: the PR group, the patients undergoing PR combined with PCO; and the PCO group, the patients undergoing PCO alone. Follow-up was at least 12 months. Radiographic results mainly included main curve Cobb, correction of per PR/PCO segment, apical vertebra rotation (AVR) and apical vertebra translation (AVT). Demographics, surgical data, complications were also recorded. Student's independent samples t test and Pearson's chi-square test were used to compare the differences between groups. Forty patients with an average age of 16.65 years were included (PR group, n = 20; PCO group, n = 20). The main curves averaged 77.56° ± 5.86° versus 78.02° ± 5.72° preoperatively and 20.07° ± 6.73° versus 33.58° ± 5.76° (p < 0.001) at the last follow-up in the PR and PCO groups, respectively. The mean correction rates were 74.30% and 56.84%, respectively (p < 0.001). The average coronal curve correction was 13.49° per release segment, which was significantly higher than the PCO correction of 6.20° (p < 0.001). The correction of apical vertebra rotation and translation in the main thoracic curve was significantly better in the PR group than in the PCO group (p < 0.05). Several minor complications in the two groups improved after conservative treatment. The multi-segment apical convex PR combined with PCO offers more advantages than PCO alone in the treatment of patients with moderate-to-severe rigid scoliosis. Owing to its excellent corrective effect and few complications, this is a high benefit-risk ratio surgical strategy for rigid scoliosis.

Usefulness of the spectral shaping dual-source computed tomography imaging technique in posterior corrective fusion for adolescent idiopathic scoliosis.

Since childhood exposure to radiation has been demonstrated to increase cancer risk with increase in radiation dose, reduced radiation exposure during computed tomography (CT) evaluation is desired for adolescent idiopathic scoliosis (AIS). Therefore, this retrospective study aimed to investigate the radiation dose of dual-source CT using a spectral shaping technique and the accuracy of the thoracic pedicle screw (TPS) placement for posterior spinal fusion (PSF) in patients with AIS. Fifty-nine female patients with thoracic AIS who underwent PSF using CT-guided TPSs were included and divided into two groups comprised of 23 patients who underwent dual-source CT (DSCT) with a tin filter (DSCT group) and 36 who underwent conventional multislice CT (MSCT group). We assessed the CT radiation dose using the CT dose index (CTDIvol), effective dose (ED), and accuracy of TPS insertion according to the established Neo's classification. The DSCT and MSCT groups differed significantly (p < 0.001) in the mean CTDIvol (0.76 vs. 3.31mGy, respectively) and ED (0.77 vs. 3.47mSv, respectively). Although the correction rate of the main thoracic curve in the DSCT group was lower (65.7% vs. 71.2%) (p = 0.0126), the TPS accuracy (Grades 0-1) was similar in both groups (381 screws [88.8%] vs. 600 screws [88.4%], respectively) (p = 0.8133). No patient required replacement of malpositioned screws. Spectral shaping DSCT with a tube-based tin filter allowed a 75% radiation dose reduction while achieving TPS insertion accuracy similar to procedures based on conventional CT without spectral shaping.

Flexibility-tilt agreement best predicts shoulder balance following posterior spine fusion for adolescent idiopathic scoliosis.

We propose a novel concept, called flexibility-tilt agreement (FTA), which could be applied intra-operatively to improve shoulder balance following posterior spine fusion for Adolescent Idiopathic Scoliosis (AIS). We retrospectively applied this concept to a cohort with thoracic-only curves, seeking to: (1) evaluate the impact of FTA and other peri-operative variables on post-operative shoulder balance, and (2) evaluate deformity characteristics associated with achieving FTA. A single-institution registry was queried for patients undergoing PSF from 2000 to 2017 with main thoracic and double thoracic curves with at least 2-year follow-up. Flexibility was defined as the Cobb angle of the unfused proximal thoracic curve (cephalad to chosen UIV) on pre-operative bender. Tilt refers to post-operative UIV tilt angle. FTA means these values cancel (Flexibility + Tilt = 0 ± 5°). Logistic regression was performed to determine the association between peri-operative variables and shoulder balance. One hundred and sixty-one patients were included, mean age 13.6years old, and 47-month mean follow-up. FTA was achieved in 74 (46%) patients and was associated with post-operative (OR = 4.59) and final (OR = 6.98) medial shoulder balance with a threshold of 6° (AUC = 0.77, p = 0.038). FTA was the best predictor of shoulder balance of all tested variables. Patients that showed flexibility-tilt agreement, or FTA, had vastly increased odds of medial and lateral shoulder balance at a minimum of 2-year follow-up for all thoracic curves. Future studies can evaluate whether applying FTA to determine intra-operative corrective maneuvers prospectively leads to improvements in shoulder balance. Level III-retrospective comparative study.

The problem of double thoracic idiopathic scoliosis: a non-systematic literature review

Objective. To analyze the current situation in the community of spine surgeons regarding the determination of the zone of posterior spinal fusion for double thoracic idiopathic scoliosis.Material and Methods. The content of 16 publications containing the results of surgical correction of double thoracic scoliotic deformities was analyzed. The number of studied clinical cohorts was 25, of which in 13 groups only the right-sided main thoracic (MT) curve (MT group) was blocked, and in 12 – both MT and left-sided proximal upper thoracic (PT) curve (MT + PT group). Four parameters were analyzed in both groups: preoperative Cobb angle, preoperative curve mobility, deformity correction, and postoperative deformity progression.Results. Significant differences were found in the MT and MT + PT groups only in two cases: for the initial Cobb angle of the PT curve and the magnitude of its correction (Cobb angle before surgery minus Cobb angle immediately after the intervention). When choosing the extent of the instrumental fusion zone, the authors of the publications included in the review were guided, first of all, by the initial magnitude of the Cobb angle of the proximal thoracic curve. In the MT + PT group, it averaged 37–40° and was 11–13° more than in the MT group. At the same time, PT curve mobility in both groups is not statistically different. The achieved correction was statistically significantly greater in the МT + РT group, despite a more severe proximal curvature as compared to the MT group. Postoperative dynamics of kyphosis (both T2–T5 and T5–T12) is insignificant. The length of the instrumental spinal fusion zone has virtually no effect on the parameters of the sagittal contour of the thoracic spine. A fairly high frequency of the adding-on phenomenon development (20.6 %) indicates the presence of a connection between this complication and the dynamics of PT curve, but the available data are not enough to formulate a final conclusion. Literature data regarding patients’ self-assessment of quality of life after surgical treatment of Lenke types 1 and 2 scoliosis are scarce, although the majority of those operated on assess the result of treatment as positive.Conclusion. The problem of determining the extent of the instrumental fusion zone for double thoracic scoliosis remains unresolved. Most surgeons focus not so much on the mobility of the proximal curve, but on its magnitude. There is no consensus in predicting the development of the adding-on phenomenon; there is little information about changes in the quality of life of patients after surgery. New research is needed.