Adolescent Idiopathic Scoliosis Curves Research Articles

Epigenetic and Genetic Factors Related to Curve Progression in Adolescent Idiopathic Scoliosis: A Systematic Scoping Review of the Current Literature.

Adolescent idiopathic scoliosis (AIS) is a progressive deformity of the spine. Scoliotic curves progress until skeletal maturity leading, in rare cases, to a severe deformity. While the Cobb angle is a straightforward tool in initial curve magnitude measurement, assessing the risk of curve progression at the time of diagnosis may be more challenging. Epigenetic and genetic markers are potential prognostic tools to predict curve progression. The aim of this study is to review the available literature regarding the epigenetic and genetic factors associated with the risk of AIS curve progression. This review was carried out in accordance with Preferential Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The search was carried out in January 2022. Only peer-reviewed articles were considered for inclusion. Forty studies were included; fifteen genes were reported as having SNPs with significant association with progressive AIS, but none showed sufficient power to sustain clinical applications. In contrast, nine studies reporting epigenetic modifications showed promising results in terms of reliable markers. Prognostic testing for AIS has the potential to significantly modify disease management. Most recent evidence suggests epigenetics as a more promising field for the identification of factors associated with AIS progression, offering a rationale for further investigation in this field.

Biological effect of dysregulated LBX1 on adolescent idiopathic scoliosis through modulating muscle carbohydrate metabolism

BACKGROUND CONTEXTAbnormal energy metabolism such as lower body weight and body mass index (BMI) and less fat mass is widely reported in patients with adolescent idiopathic scoliosis (AIS) and has been implicated in deformity development. However, the underlying mechanism is largely unclear. LBX1 is one of the promising AIS predisposing genes validated by multicenter studies. PURPOSEThis study aimed to identify differentially expressed proteins (DEPs) relating to energy metabolism in AIS by using proteomic and metabolic analysis and to explore if the expression of these DEPs is associated with clinical parameters and modulated by LBX1. STUDY DESIGNThis is a cross-sectional study using clinical data and biological samples followed by basic study using a cellular model. PATIENT SAMPLEPlasma samples were collected from Chinese girls with nonprogressive and progressive AIS (N=7 and 8, respectively) and age-matched healthy girls (N=50). Paraspinal muscle tissues were collected intraoperatively from concave and convex side of the apex of the major spinal curve in AIS (N=24) and either side from nonscoliosis patients (N=14). OUTCOME MEASURESRadiological Cobb angle and basic anthropometric data of recruited subjects were measured. The DEPs and metabolites were compared in plasma using proteomics and metabolomics technique. The relative expression of selected genes was measured in muscles. METHODSPlasma samples from AIS were collected at first clinical visit and were further divided into nonprogressive or progressive groups according to Cobb angle changes in 6-year follow-up. Age-matched healthy girls were recruited as control. High-performance liquid chromatography-mass spectrometry based proteomic analysis was carried out in three groups to identify DEPs and their annotated metabolic pathways. An independent cohort was used for validation by gas chromatography-mass spectrometry based metabolomic analysis. Paraspinal muscles were subjected to quantitative polymerase chain reaction (qPCR) followed by correlation analysis. Human skeletal muscle myoblast (HSMM) was used as the cellular model. RESULTSThe likelihood of aberrant galactose metabolism and glycolysis was found to be associated with AIS curve progression as evidenced by the thirteen DEPs and seven related metabolites according to proteomic and metabolomic analysis. Some of the DEPs showed significantly altered expression in AIS concave and convex sides paraspinal muscles compared with those in nonscoliosis control. Four DEPs were found significantly and negatively correlated with LBX1 in AIS convex side paraspinal muscles. Overexpressing LBX1 in HSMM cells led to increased expression of three DEPs and decreased expression of three DEPs, respectively. CONCLUSIONSThis is the first integrated proteomic and metabolomic analysis on AIS. Our findings show dysregulated galactose metabolism and glycolysis pathways in progressive group of AIS, suggesting the presence of abnormal energy metabolism at early stage of this disease, and their association with higher risk of progressing into more severe curvature. Evidence from ex vivo study with human muscle biopsies and in vitro study with human myoblast cells propose the possible effect of LBX1 on these two pathways in skeletal muscles. The present study provides new evidence of LBX1 function in AIS via modulating effect on the expression of energy metabolism related genes. This study might provide new insights into etiopathogenesis and development of novel treatment strategy targeting on abnormal body weight and BMI in patients with AIS. Additionally, the plasma proteomic and metabolomic studies suggested new candidates as biomarkers for establishing predictive model for AIS onset/progression.

Predictive value of single-nucleotide polymorphisms in curve progression of adolescent idiopathic scoliosis.

Genetic diagnosis is a promising approach because several single-nucleotide polymorphisms (SNPs) associated with adolescent idiopathic scoliosis (AIS) progression have been reported. We review the predictive value of SNPs in curve progression of adolescent idiopathic scoliosis. We reviewed DNA-based prognostic testing to predict curve progression. Then, the multiple polymorphisms in loci related to AIS progression were also reviewed, and we elucidated the predictive value of SNPs from four functional perspectives, including endocrine metabolism, neuromuscular system, cartilage and extracellular matrix, enzymes, and cytokines. The ScoliScores were less successful predictors than expected, and the weak power of predictive SNPs might account for its failure. Susceptibility loci in ESR1, ESR2, GPER, and IGF1, which related to endocrine metabolism, have been reported to predict AIS progression. Neuromuscular imbalance might be a potential mechanism of scoliosis, and SNPs in LBX1, NTF3, and SOCS3 have been reported to predict the curve progression of AIS. Susceptibility loci in SOX9, MATN1, AJAP1, MMP9, and TIMP2, which are related to cartilage and extracellular matrix, are also potentially related to AIS progression. Enzymes and cytokines play essential roles in regulating bone metabolism and embryonic development. SNPs in BNC2, SLC39A8, TGFB1, IL-6, IL-17RC, and CHD7 were suggested as predictive loci for AIS curve progression. Many promising SNPs have been identified to predict the curve progression of AIS. However, conflicting results from replication studies and different ethnic groups hamper their reliability. Convincing SNPs from multiethnic populations and functional verification are needed.

Dual-Rod Instrumentation Via the Anterior Approach for Thoracolumbar and Lumbar Adolescent Idiopathic Scoliosis

Background: Posterior spinal fusion with pedicle screw instrumentation is currently the standard technique for spinal surgery. However, the anterior approach remains useful for thoracolumbar and lumbar (TL/L) lesions, such as in adolescent idiopathic scoliosis (AIS) 1–4 and spinal injuries 5,6 . We previously documented that long-term radiographic findings and clinical measures were satisfactory in patients with TL/L AIS treated with anterior dual-rod instrumentation 1 . Description: This surgical technique is indicated for single TL/L (Lenke 5) curves and is performed with use of extrapleural retroperitoneal approaches. The extrapleural cavity is connected to the retroperitoneal space by diaphragmatic transection. The lateral aspect of the vertebral bodies is exposed by retracting the psoas major muscle posteriorly from the intervertebral discs. Segmental vascular bundles are divided with coagulation and/or ligation. Care should be taken to reflect the psoas in its entirety and avoid an intramuscular approach to prevent bleeding injury to nerves, including the femoral, ilioinguinal, and genitofemoral nerves, as well as ureteral injury. After the intervertebral discs and cartilage plates are removed to the vertebral end plates, 2 screws are inserted in each vertebral body through a vertebral staple 1,4 . The anterior rod is then placed in the screw heads and rotated anteriorly, providing 3-dimensional correction of kyphotic deformities with lordosis production 1,4 . After the posterior rod is applied in the same manner as the anterior rod, compression forces are applied between the screws to correct scoliosis 1,4 . The compression force is first applied to the posterior rod so that kyphosis can be corrected more effectively 1,4 . Alternatives: Posterior pedicle screw instrumentation techniques are widely utilized for TL/L AIS curve correction. However, anterior techniques have frequently also been applied to the curve. Dwyer et al. 7 first reported the use of anterior spinal fusion (ASF) with a single braided cable connecting vertebral screws for the treatment of TL/L AIS, and Zielke et al. 8 modified that procedure by replacing the cable with a threaded rod. Although these instrumentation techniques and other single anterior rod techniques such as the Texas Scottish Rite Hospital System effectively correct scoliosis in the coronal plane and improve vertebral derotation 1,9 , poor sagittal and rotational plane deformity correction, implant weakness, and high incidence of pseudarthrosis remain unresolved issues 1 . Rationale: The fundamental advantages of the anterior approach in dual-rod instrumentation are the ability to achieve 3-dimensional correction with extremely low rates of pseudarthrosis and implant failure 1,10–12 . Furthermore, the fusion is expected to include fewer motion segments than with posterior systems (usually 1 level less distally and proximally). However, low skeletal maturity and a TL/L to thoracic Cobb ratio of <1.25 appeared to be important factors for postoperative curve progression of the thoracic coronal deformity following ASF for the treatment of Lenke 5 curves 1,13 . In addition, subjacent disc wedging may occur when the subjacent disc is nearly parallel before surgery 1,14 . Expected Outcomes: The described technique is expected to provide 3-dimensional spinal correction. In a previous study, 30 patients with Lenke 5 AIS were followed for a mean of 17 years 1 . The mean TL/L Cobb angle correction rate and correction loss were 79.8% and 3.4°, respectively, at the time of the latest follow-up 1 . The average percent of predicted forced vital capacity and of forced expiratory volume in 1 second were 91.8% and 81.8%, respectively 1 . The average total score on the Scoliosis Research Society-30 outcome instrument was 4.21. No instrumentation failure, pseudarthrosis, or clinically relevant neurovascular complications were observed 1 . Important Tips: This technique is applicable to Lenke 5 AIS curves. However, the anterior approach can also be utilized for other TL/L lesions.The anterior procedure is accomplished via extrapleural retroperitoneal approaches with diaphragmatic transection.Care should be taken to reflect the psoas in its entirety and avoid an intramuscular approach to prevent bleeding and nerve and ureteral injuries. Acronyms & Abbreviations: SRS-30 = Scoliosis Research Society-30

Intraoperative halo-femoral traction during posterior spinal arthrodesis for adolescent idiopathic scoliosis curves between 70° and 100°: a randomized controlled trial.

Surgical management of scoliosis curves between 70° and 100° remains controversial. The authors designed this randomized controlled trial to validate the efficacy of intraoperative halo-femoral traction (IOHFT) in patients with adolescent idiopathic scoliosis (AIS), Cobb angles between 70° and 100°, and flexibility < 35%. The authors prospectively recruited and randomized 29 patients with severe AIS scheduled for posterior surgery into a traction group or control (nontraction) group. The primary outcome measures were operative time, blood loss, and length of hospital stay. Secondary outcomes included degree of spine deformity correction, traction-related complications, and health-related quality of life. In the traction group, the average preoperative Cobb angle was 83.2°, with an average 20.6% flexibility. The average postoperative Cobb angle was 16.1° and the major curve was 18.3° at the final follow-up. In the control group, the average preoperative major curve was 80.3° with 22.8% flexibility. The average postoperative Cobb angle was 16.1° and the major curve was 18.1° at the final follow-up. The operative duration was 325.7 minutes for the traction group and 385.4 minutes for the control group (p = 0.018). Compared with the control group, the traction group had a 29.5% reduction in intraoperative blood loss and a significantly lower rate of blood transfusion (13.3% vs 50.0%, p = 0.033). There were no neurological complications in either group. One patient in the traction group had a superficial infection at the traction site. Use of IOHFT contributed to significant reductions in operative time and blood transfusion requirements, with no added morbidity. It is an effective and safe method to assist correction of AIS curves between 70° and 100° and flexibility < 35%.

Application of deep learning upon spinal radiographs to predict progression in adolescent idiopathic scoliosis at first clinic visit.

BackgroundPrediction of curve progression risk in adolescent idiopathic scoliosis (AIS) remains elusive. Prior studies have revealed the potential for three-dimensional (3D) morphological parameters to prognosticate progression, but these require specialized biplanar imaging equipment and labor-intensive software reconstruction. This study aimed to formulate a deep learning model with standing posteroanterior (PA) X-rays at first clinic visit to differentiate between progressive (P) and non-progressive (NP) curves.MethodsFor this retrospective cohort study, we identified patients presenting with AIS between October 2015 to April 2020 at our tertiary referral centre. Patients with mild curvatures (11 – 30o) who were skeletally immature (Risser sign of ≤2) were recruited. Patients receiving biplanar X-ray radiographs (EOS™) were divided between a training-cross-validation cohort (328 patients) and independent testing cohort (110 patients). Another 52 patients receiving standard PA spinal X-rays were recruited for cross-platform validation. Following 3D reconstruction, we designated the major curve apex upon PA X-rays as the region of interest (ROI) for machine learning. A self-attentive capsule network was constructed to differentiate between curves manifesting P and NP trajectories. A two-stage transfer learning strategy was introduced to pre-train and fine-tune the model. Model performance (accuracy, sensitivity, specificity) was compared to that of traditional convolutional neural networks (CNNs) and a clinical parameter-based logistic regression model.Findings3D reconstruction identified that apical rotation of the major curve and torsion were significantly different between P and NP curve trajectories. Our predictive model utilizing an ROI centered on the major curve apex achieved an accuracy of 76.6%, a sensitivity of 75.2% and a specificity of 80.2% upon independent testing. Cross-platform performance upon standard standing PA X-rays yielded an accuracy of 77.1%, a sensitivity of 73.5% and a specificity of 81.0%. Errors in prediction occurred when the degree of apical rotation / torsion was discrepant from that of the subsequent curve trajectory but could be rectified by considering serial X-rays. Performance was superior to that of traditional CNNs as well as clinical parameter-based regression models.InterpretationThis is the first report of automated prediction of AIS curve progression based on radiomics and deep learning, towards directing treatment strategy at first visit. Patients predicted to be at-risk of progression may be counselled to receive early bracing with enforcement of treatment compliance. Over-treatment may be avoided in curves deemed to be non-progressive. Results need to be consolidated in larger sample populations of different ethnicities.FundingThe Society for the Relief of Disabled Children (SRDC).

Efficacy of Routine Intraoperative Cranio-Femoral Traction in Surgical Treatment of Adolescent Idiopathic Scoliosis Curves Measuring Between 50° and 90°.

Retrospective Comparative Study, Level III. In patients with scoliosis >90°, cranio-femoral traction (CFT) has been shown to obtain comparable curve correction with decreased operative time and blood loss. Routine intraoperative CFT use in the treatment of AIS <90° has not been established definitively. This study investigates the effectiveness of intraoperative CFT in the treatment of AIS between 50° and 90°, comparing the magnitude of curve correction, blood loss, operative time, and traction-related complications with and without CFT. 73 patients with curves less than 90° were identified, 36 without and 37 with cranio-femoral traction. Neuromuscular scoliosis and revision surgery were excluded. Age, preoperative Cobb angles, bending angles, and curve types were recorded. Surgical characteristics were analyzed including number of levels fused, estimated blood loss, operative time, major curve correction (%), and degree of postoperative kyphosis. Patients with traction had significantly higher preoperative major curves but no difference in age or flexibility. Lenke 1 curves had significantly shorter operative time and improvement in curve correction with traction. Among subjects with 5 to 8 levels fused, subjects with traction had significantly less EBL. Operative time was significantly shorter for subjects with 5-8 levels and 9-11 levels fused. Curves measuring 50°-75° showed improved correction with traction. Intraoperative traction resulted in shorter intraoperative time and greater correction of major curves during surgical treatment of adolescent idiopathic scoliosis less than 90°. Strong considerations should be given to use of intraoperative CFT for moderate AIS.

Surgical Outcome Prediction Using a Four-Dimensional Planning Simulation System With Finite Element Analysis Incorporating Pre-bent Rods in Adolescent Idiopathic Scoliosis: Simulation for Spatiotemporal Anatomical Correction Technique.

An optimal surgical strategy for adolescent idiopathic scoliosis (AIS) is to provide maximal deformity correction while preserving spinal mobile segments as much as possible and obtaining a balanced posture. From a spatiotemporal deformity correction standpoint, we recently showed that anatomical four-dimensional (4D) spinal correction could be accomplished by curving the rod. In the surgical procedure, two rods are bent identically to confirm spinal anatomical alignment without referring to the intraoperative alignment of the deformity. Therefore, anatomically designed rods have been developed as notch-free, pre-bent rods for easier anatomical reconstruction. In addition to providing the best spinal instrumentation configurations as pre-bent rods, prediction of surgical outcome along with its biomechanical impact can be obtained by simulation of the surgical procedures with computer modeling. However, an objective model that can simulate the surgical outcome in patients with AIS has not been completely elucidated. The present study aimed to compare simulated deformity corrections based on our newly developed spatiotemporal morphological 4D planning simulation system incorporating pre-bent rods and actual deformity corrections in patients with AIS. A consecutive series of 47 patients who underwent anatomical posterior correction for AIS curves were prospectively evaluated. After multilevel facetectomy, except for the lowest instrumented segment, 11 types of pre-bent rods were used. Patient demographic data, radiographic measurements, and sagittal rod angles were analyzed within 1 week of surgery. Our simulation system incorporating pre-bent rods showed a significant correlation with the actual postoperative spinal alignment. The present study demonstrated the feasibility of our simulation system and the ability to simulate the surgical procedure using the pre-bent rods. The simulation system can be used to minimize the differences between the optimal and possible outcomes related to the instrumentation levels and rod shapes. Preoperative assumption of rod shape and length can contribute to a reduction in operative time which decreases blood loss and risk of infection. The results of the finite element analysis in the simulation system measured for each individual patient would also provide a more realistic representation of the surgical procedures.

Prediction of long-term postoperative results of disc wedge and vertebral tilt with intraoperative prone radiograph in posterior correction of thoracolumbar/lumbar curve in adolescent idiopathic scoliosis: a minimum 5-year follow-up

BACKGROUND CONTEXTPreservation of the more mobile lumbar segments is important during thoracolumbar/lumbar scoliosis surgery; however, the remaining disc wedge angle (DWA) below lowermost instrumented vertebra (LIV) and vertebral body tilt below LIV (LIV+1 tilt) can cause curve progression. PURPOSEThis study aimed to evaluate the efficacy of intraoperative radiograph to predict the postoperative DWA below LIV and LIV+1 tilt on standing radiographs in patients with LIV of L3 or L4. STUDY DESIGN/SETTINGRetrospective cohort study PATIENT SAMPLEA total of 235 patients with idiopathic scoliosis who underwent posterior correction and fusion for the structural thoracolumbar curve and were followed up for >5 years were reviewed. OUTCOME MEASURESDWA below LIV, LIV+1 tilt, Cobb angle, trunk shift, apical vertebra translation, and pelvic parameters were measured. METHODSCorrelation between intraoperative and postoperative measurements of DWA below LIV and LIV+1 tilt were assessed. Additional analysis was performed to identify risk factors and prognosis of LIV+1 tilt ≥10° and DWA below LIV of ≥4° RESULTSLIV+1 tilt measured on intraoperative radiograph was significantly correlated with the postoperative 5-day and postoperative 5-year evaluation in both groups. However, the intraoperative DWA below LIV was only correlated with the postoperative 5-year value in the L3 group (p=.018). At the 5-year follow-up, patients with LIV+1 tilt ≥10° on intraoperative radiography showed significantly greater LIV+1 tilt (p<.001), apical vertebral translation (p<.001), thoracic curve (p=.008), and thoracolumbar curve (p<.001) than patients with LIV+1 tilt <10°. Intraoperative DWA below LIV of ≥4° was only associated with higher DWA below LIV at the 5-year follow-up. CONCLUSIONSIntraoperative measurement of LIV+1 tilt was correlated with long-term postoperative outcomes, and intraoperative LIV+1 tilt ≥10° was associated with a less favorable radiographic outcome. Intraoperative DWA below LIV demonstrated less correlation with postoperative values and was not a prognostic factor for other radiographic parameters.

Asymmetrical activation and asymmetrical weakness as two different mechanisms of adolescent idiopathic scoliosis

There have been many studies on adolescent idiopathic scoliosis related abnormal muscle contractions of the spine. However, previous studies using surface electromyography to investigate paraspinal muscle asymmetry are controversial, lacking in clarity of results, and hindered by methodological limitations. The purpose of this study was to investigate the relationship between imbalance factors including surface electromyography activity according to the scoliosis curve type and leg length discrepancy and adolescent idiopathic scoliosis curve types. Seventy-nine patients with scoliosis were prospectively enrolled and were divided into five types: single thoracic, thoracolumbar, lumbar, double thoracic, and double major. Cobb angle and structural variables were measured. Surface electromyography examinations were conducted at the 7th, 12th thoracic erector spinae, 3rd lumbar erector spinae, and multifidus muscles during the superman position keeping prone spinal extension to lift the arms and legs off the floor. Whole spine radiographs were obtained to measure the Cobb angle, coronal imbalance, pelvic height and angle, and femoral head height. In the double major, thoracolumbar, and lumbar types, the mean root mean squared (RMS) EMG amplitudes were significantly higher on the convex side than the concave side (P < 0.005). In the DM type, the mean RMS EMG amplitudes of EST7 and ESL3 where the apex was located were significantly higher at the convex side than those of the concave side (P < 0.005, effect size (Cohen’s d) for EST7/ESL3: 0.517/0.573). The TL and L types showed a similar pattern. The mean RMS EMG amplitudes of the EST12 concave side and MuL3 and ESL3 concave sides were significantly lower than those of the convex side in the TL and L types, respectively (P < 0.008, effect size (Cohen’s d) for EST12/MuL3/ESL3: 0.960/0.264/0.448). Conversely, there were no significant differences in the single thoracic and double thoracic types. All structural variables (coronal imbalance, pelvic height and angle, and femur head height) were higher in the lumbar type, but only coronal imbalance was significantly different (P < 0.05). Different patterns of asymmetry of paraspinal muscles and structural variables were described based on the curvature of the spine. L type showed that EMG activity was asymmetric in the paraspinalis muscles where the apex was located and that structural asymmetry, such as coronal imbalance was significantly greater than other types. DM type showed similar paraspinalis asymmetry pattern to the ST type but there was no structural asymmetry in DM and ST types. TL type has the features of both thoracic and lumbar origins. Understanding these could contribute to the management in correcting scoliosis.

Morphometric analysis of the proximal thoracic pedicles in Lenke II and IV adolescent idiopathic scoliosis: an evaluation of the feasibility for pedicle screw insertion.

Pedicles on the concave side of the proximal thoracic (PT) curve in adolescent idiopathic scoliosis (AIS) patients with Lenke II and IV deformities tend to be narrow and dysplastic, making pedicle screw (PS) insertion challenging. The aim of this study was to evaluate the feasibility for PS placement in these patients using pedicle chord length, diameter, and channel morphology. In this retrospective study, 56 consecutive AIS patients with Lenke II or IV curves who underwent instrumented posterior spinal fusion (PSF) were studied. The mean age at surgery was 14.8years and the mean PT curve measured 45°. Two independent investigators evaluated all visible pedicles from T1 to T6 vertebral levels using axial images from intraoperative computed tomography-guided navigation recording the pedicle: (1) maximum transverse diameter 'd' at the isthmus, (2) maximum chord length 'l', and (3) qualitative assessment of the channel morphology (types A-D). Two hundred and sixty-eight concave and 264 convex pedicles were measured. The mean 'd' of the concave pedicles at T3 and T4 was < 3.0mm, compared to > 5.0mm for the convex counterparts (p < 0.001). Of all concave pedicle channels, 48% had morphology characteristics that were riskier for PS cannulation (type C or D) compared to 2% of all convex pedicle channels (type A or B) (p < 0.001). Almost half of all concave pedicles have morphologic characteristics that make them too small to accommodate a PS. Though PSs could be inserted using an in-out-in technique in these patients, alternative fixation anchors may improve strength and safety.

Resolution of the lumbosacral fractional curve and evaluation of the risk for adding on in 101 patients with posterior correction of Lenke 3, 4, and 6 curves.

In double and triple major adolescent idiopathic scoliosis curves it is still controversial whether the lowest instrumented vertebra (LIV) should be L3 or L4. Too short a fusion can impede postoperative distal curve compensation and promote adding on (AON). Longer fusions lower the chance of compensation by alignment changes of the lumbosacral curve (LSC). This study sought to improve prediction accuracy for AON and surgical outcomes in Lenke type 3, 4, and 6 curves. This was a retrospective multicenter analysis of patients with adolescent idiopathic scoliosis who had Lenke 3, 4, and 6 curves and ≥ 1 year of follow-up after posterior correction. Resolution of the LSC was studied by changes of LIV tilt, L3 tilt, and L4 tilt, with the variables resembling surrogate measures for the LSC. AON was defined as a disc angle below LIV > 5° at follow-up. A matched-pairs analysis was done of differences between LIV at L3 and at L4. A multivariate prediction analysis evaluated the AON risk in patients with LIV at L3. Clinical outcomes were assessed by the Scoliosis Research Society 22-item questionnaire (SRS-22). The sample comprised 101 patients (average age 16 years). The LIV was L3 in 54%, and it was L4 in 39%. At follow-up, 87% of patients showed shoulder balance, 86% had trunk balance, and 64% had a lumbar curve (LC) ≤ 20°. With an LC ≤ 20° (p = 0.01), SRS-22 scores were better and AON was less common (26% vs 59%, p = 0.001). Distal extension of the fusion (e.g., LIV at L4) did not have a significant influence on achieving an LSC < 20°; however, higher screw density allowed better LC correction and resulted in better spontaneous LSC correction. AON occurred in 34% of patients, or 40% if the LIV was L3. Patients with AON had a larger residual LSC, worse LC correction, and worse thoracic curve (TC) correction. A total of 44 patients could be included in the matched-pairs analysis. LC correction and TC correction were comparable, but AON was 50% for LIV at L3 and 18% for LIV at L4. Patients without AON had a significantly better LC correction and TC correction (p < 0.01). For patients with LIV at L3, a significant prediction model for AON was established including variables addressed by surgeons: postoperative LC and TC (negative predictive value 78%, positive predictive value 79%, sensitivity 79%, specificity 81%). An analysis of 101 patients with Lenke 3, 4, and 6 curves showed that TC and LC correction had significant influence on LSC resolution and the risk for AON. Improving LC correction and achieving an LC < 20° offers the potential to lower the risk for AON, particularly in patients with LIV at L3.

In vivo deformation of anatomically pre-bent rods in thoracic adolescent idiopathic scoliosis

Some surgical strategies can maintain or restore thoracic kyphosis (TK); however, next-generation surgical schemes for adolescent idiopathic scoliosis (AIS) should consider anatomical corrections. A four-dimensional correction could be actively achieved by curving the rod. Thus, anatomically designed rods have been developed as notch-free, pre-bent rods for easier anatomical reconstruction. This study aimed to compare the initial curve corrections obtained using notch-free rods and manually bent, notched rods for the anatomical reconstruction of thoracic AIS. Two consecutive series of 60 patients who underwent anatomical posterior correction for main thoracic AIS curves were prospectively followed up. After multilevel facetectomy, except for the lowest instrumented segment, either notch-free or notched rods were used. Patient demographic data, radiographic measurements, and sagittal rod angles were analyzed within 1 week after surgery. Patients with notch-free rods had significantly higher postoperative TK than patients with notched rods (P < .001), but both groups achieved three-dimensional spinal corrections and significantly increased postoperative rates of patients with T6–T8 TK apex (P = .006 for notch-free rods and P = .008 for notched rods). The rod deformation angle at the concave side was significantly lower in the notch-free rods than in the notched rods (P < .001). The notch-free, pre-bent rod can maintain its curvature, leading to better correction or maintenance of TK after anatomical spinal correction surgery than the conventional notched rod. These results suggest the potential benefits of anatomically designed notch-free, pre-bent rods over conventional, manually bent rods.

Does Implant Density Impact Three-Dimensional Deformity Correction in Adolescent Idiopathic Scoliosis with Lenke 1 and 2 Curves Treated by Posterior Spinal Fusion without Ponte Osteotomies?

Study DesignRetrospective cohort study.PurposeTo determine whether implant density impact three-dimensional deformity correction in posterior spinal fusion (PSF) without Ponte osteotomies (POs) for patients with Lenke 1 and 2 adolescent idiopathic scoliosis (AIS).Overview of LiteratureCurrently, the optimal pedicle screw (PS) density for flexible moderate-sized thoracic AIS curve correction is still controversial. There are limited data regarding the impact of implant density on three-dimensional correction in PSF without the use of PO for thoracic AIS surgery.MethodsA database of patients with AIS with Lenke 1 and 2 curves treated with PSF without PO and instrumented with PSs and ≥2-year follow-up was reviewed. The preoperative, immediate, and final follow-up postoperative radiographs were analyzed. The correlation between PS density and the following factors were determined: major curve correction (MCC), correction index (CI; MCC/curve flexibility), kyphosis angle change, and rib index (RI) correction. Then, patients were divided into low-density (LD) and high-density (HD) groups according to mean PS density for the entire cohort (1.5 PS per level). Demographics and radiographic and clinical outcomes were compared between groups.ResultsThe study included 99 patients with Lenke 1 and 23 patients with Lenke 2 AIS. The average MCC was 67.2%. There was no correlation between screw density and these parameters: MCC (r=0.10, p=0.26), CI (r=0.16, p=0.07), change in T2–T12 kyphosis angle (r=−0.13, p=0.14), and RI correction (r=−0.09, p=0.37). Demographic and preoperative radiographic parameters were similar between the LD and HD groups. At the latest follow-up, there were no differences between the two groups in regard to MCC, CI, change in T2–T12 kyphosis angle, RI correction, and Scoliosis Research Society-30 scores (all p>0.05).ConclusionsThis study revealed no significant correlation between screw density and curve correction in any planes. HD construct may not provide better deformity correction in patients with flexible and moderate thoracic AIS undergoing PSF without PO.

A novel classification method for mild adolescent idiopathic scoliosis using 3D ultrasound imaging

Mild adolescent idiopathic scoliosis (AIS), with Cobb<20°, was hypothesized as the right stage to intervene to prevent progression. AIS curve can be categorized into either structural or non-structural depending on the spine morphology (flexibility). Using X-ray to characterize AIS curves remains the clinical gold standard while compromising the risks of radiation exposure. In previous works, 3D ultrasound imaging had proved the reliability of the coronal spinal curvature measurement. This research aimed at developing a mild AIS classification scheme through examining spine flexibility using 3D ultrasound imaging.For the preliminary study, 90 mild AIS subjects (21 ​M and 69 ​F; Age:14.5 ​± ​1.7 years old; Cobb: 18.2 ​± ​6.4°) underwent both 3D ultrasound and X-ray scanning on the same day. For each case, a clinician measured Cobbs and denoted major curve as ground truth. Bending Asymmetry Index (BAI) was developed to indicate the presence of a possible structural curve. The curve classification was coded to a modified Lenke classification for mild cases (m-Lenke). The results of 3D ultrasound classification were evaluated with the X-ray.It was shown that 70.1% of the subjects had identical curve classification results and 72.0% had the correct major curve detection. Lumbar-dominated curves had distinctive performance (p ​= ​0.91, r ​= ​0.91) against others. The study demonstrated the possibility of a 3D ultrasound-based method for mild AIS curve classification. The discrepancies could be partially explained by the limitations of the ultrasound scanning in proximal thoracic region. Subsequent studies will validate the proposed method with a larger cohort.

Ponte osteotomies in a matched series of large AIS curves increase surgical risk without improving outcomes.

The routine use of Ponte osteotomies in adolescent idiopathic scoliosis (AIS) surgery is controversial with conflicting data for coronal plane correction and little analysis in the sagittal plane. The objective of this study was to analyze the efficacy of Ponte osteotomies in large curve AIS. A single institution, prospectively-collected series of consecutive AIS patients who had Ponte osteotomies (P cohort) was directly matched to patients with no Pontes (NP cohort) by age, gender, Lenke classification, surgeon, coronal, and sagittal Cobb angles. The radiographic review included adjusted values using a 3D-derived published formula for preoperative T5-T12 kyphosis. Patient-reported outcomes (PROs) were assessed with the SRS-30 and Spinal Appearance Questionnaire (SAQ). There were 68 patients (34/cohort) with minimum 2-year follow-up with no differences between P and NP cohorts in age, preoperative coronal Cobb (74.5° vs 70.8°), flexibility index, measured or 3D-adjusted T5-T12 kyphosis. Rod material/diameter, fusion levels, blood loss, and operative time did not differ, but implant density was higher in the P group (1.53 vs 1.31, p < 0.001). The P group had 7.9% greater coronal Cobb correction (66.6% vs 58.7%, p < 0.003) without difference in final Cobb angles (24.7° vs. 29.1°, p = 0.052). There were no differences in measured or adjusted T5-T12 kyphosis in the sagittal plane. The P group had a 15% rate of critical intraoperative neuromonitoring changes versus 0% in the NP group (p = 0.053). At follow-up, there were no differences in scoliometer measurements or any domain of SRS-30 or SAQ scores. In this first reported matched series of AIS patients, Ponte osteotomies provide small radiographic gains in the coronal plane with no improvement in the sagittal plane and no change in truncal rotation. There was a higher risk of critical intraoperative neuromonitoring changes, and no benefits in patient-reported outcomes. This calls into question the routine use of Ponte osteotomies in AIS, even for curves averaging 70 degrees. II.

Fate of Thoracic Curves in Adolescent Idiopathic Scoliosis after Selective Thoracic Fusion: Systematic Review of Literature and Meta-Analysis

Background Data: In adolescent idiopathic scoliosis (AIS), the upper thoracic spine (T1–T5) may represent an additional curve called the proximal thoracic curve (PTC), which is nearly equal and opposite to the main thoracic curve (MTC); this is a classic example of a ‘‘double thoracic curve pattern.” So, after selective thoracic fusion (STF) for MTC by either anterior or posterior instrumentation and fusion, what happens to the noninstrumented PTC and instrumented MTC? Study Design: Systematic review of literature and meta-analysis. Purpose: To evaluate the fate of the noninstrumented PTC and instrumented MTC after STF for the MTC by either anterior or posterior instrumentation and fusion. Methods: This study was conducted by searching the PubMed and Cochrane databases and included patients with AIS treated by STF between 1999 and 2020. The type of approach, degree of correction achieved in MTC, PTC, and apical vertebral rotation (AVR), and complications rate were reported independently by two authors. Results: Our systematic review yielded 1686 patients, with 18 studies meeting the required criteria. MTC has been corrected by 24.89 ± 8.45 degrees, while PTC has been corrected by 14.94 ± 7.18 degrees. Cobb’s angle was reported in seven studies for MTC angle and four studies for lumbar and thoracolumbar curves angle and has been corrected by 19.68 ± 6.55 degrees. Moreover, shoulder tilt has been corrected by 0.83 ± 0.83. Data for correction of AVR was reported in two studies and has been corrected by 15.95 ± 4.65 degrees. Conclusion: Anterior and posterior spinal fusion had no statistical significance difference regarding MTC, shoulder tilt, and AVRcorrection. However, PTC corrections was more significant after anterior spinal fusion (ASF) than posterior spinal fusion (PSF). (2021ESJ228)

Results of posterior only approach for adolescent idiopathic scoliosis

Introduction: Adolescent Idiopathic Scoliosis (AIS) is most common type of scolisis which is affecting girls more than boys. Affecting children between age 10 to18. AIS curves progress during radip growth period of child. Locate usually at thoracic level and involves right convex curve. Due to cosmetic reasons, pain and in some cases due to neurological involvement such cases needs operative involvement. In this study involves 20 such patients operated with posterior spinal approach and fixation for the same and followed up for one months for radiographic and clinical outcomes.Materials and Methods: 20 patients out of which 5 male and 15 female with AIS were managed with posterior spinal pedicle screws instrumentations and follow-up with various criteria regarding its outcomes such as postoperative pain relief, cobb’s angle, average screws insertion, average level of fixation, mean duration of surgery, blood loss, and post operative complications such as neurological deficit, infection or implant failure.Results: In this study which was done on 20 patient. Most common type of lenke’s curve is Type-1. Average Pre operative VAS score was 8.5 that Reduced to 1.9 Post operative. Average Pre operative cobb’s angle in all patients were 57.15 which is average 11.65 post operative, after 1 year of follow-up average cobb’s angle were 17.2 degrees. So average loss in correction after 1 year is 5.55. Average screw needed in this fixation is 15.6. Range minimum of 12 to maximum 19 screws required in fixation. In all 20 patients average 1.35 screws were fixed per level vertebrae. So basically, it is low density pedicle screw fixation. Average duration of surgery time is mean 6 hours 25 minutes. Range from minimum of 5 hours to max 9 hours. Mean age was 16.1. Mean blood loss was 773.5 mL. one patient developed post operative neurological deficit which progressively recovered within six months, no other significant complication in any patient was observed.Conclusion: Based upon the results obtained from this review of 20 patients of AIS with minimum one year of follow-up we suggest that the all-screw method is efficient and safe.The outcomes in three-dimensional correction are satisfactory and comparable.The curve maintenance is good with minimal loss of correction. Compared with age-matched healthy populations, these patients did present some limitations on their physical health, as assessed by the SRS-30 questionnaire.

Double-sided vertebral body tethering of double adolescent idiopathic scoliosis curves: radiographic outcomes of the first 13 patients with 2years of follow-up.

In skeletally immature patients with adolescent idiopathic scoliosis (AIS), vertebral body tethering (VBT) as a fusionless minimally invasive treatment option has been shown to correct the deformity by growth modulation. This prospective cohort study aimed to present the minimum 2years' results of double-sided VBT applied to double curves of 13 skeletally immature patients with AIS. Thirteen skeletally immature patients with AIS and double curves were included. All patients were followed up within a brace for at least 6weeks. A decision to proceed with surgery was established after the detection of curve progression within the brace (> 40° thoracic, > 35° lumbar) with a minimum curve flexibility of 30%. Patients had an average age of 11.8years, average follow-up duration of 36.4months (range 24 to 46), average preoperative main thoracic/thoracolumbar or lumbar curve magnitudes of 48.2°/45.3°. An average of 11.8 levels of tethering was undertaken. Thoracic screws were placed thoracoscopically, while mini-thoracotomy/lumbotomy was added for thoracolumbar levels. Postoperatively, an average first erect thoracic/thoracolumbar major curve magnitudes of 17.3°/14.3° were acquired, while they improved to 9.7°/8.2° at the last follow-up. No neurologic or implant-related complications were acquired. Double-sided VBT was detected to provide 80% of thoracic (48.2° to 9.7°) and 82% of thoracolumbar-lumbar curve correction (45.3° to 8.2°) as a result of average two years. As being a growth modulating treatment option, double-sided VBT as applied under strict inclusion criteria was shown to be safe and effective for the correction of double curves in skeletally immature patients with AIS, by yielding a gradual, growth-assisted correction of both curves together with the preservation of coronal-sagittal balance without any major complications.

Impact of multilevel facetectomy on segmental spinal flexibility in patients with thoracic adolescent idiopathic scoliosis

BackgroundThe aim of this study was to intraoperatively assess the effects of multilevel facetectomy on segmental spinal flexibility in patients with thoracic adolescent idiopathic scoliosis. MethodsTwenty patients who underwent posterior thoracic adolescent idiopathic scoliosis curve correction were evaluated. Compressive or distractive loaded force of 50N was applied on the handle of a compressor or distractor connected to the necks of pedicle screws inserted at T7 to T11. Segmental spinal flexibility rates were calculated based on the distance between screw heads under the loaded and unloaded conditions. In addition, the flexibility rates were obtained before and after multilevel facetectomy. FindingsAbsolute flexibility rates of all segments significantly increased after multilevel facetectomy under both compressive and distractive forces (P < 0.01). The absolute change in the flexibility rate was significantly higher at the concave side than at the convex side under both compressive (P < 0.01) and distractive loaded forces (P = 0.046). No significant correlation was found between change in the flexibility rates and preoperative Cobb angle or preoperative curve flexibility. InterpretationFrom a biomechanical point of view, multilevel facetectomy provides proper spinal flexibility to improve the correction rate of posterior adolescent idiopathic scoliosis surgery. The effects are higher at the concave side than at the convex side.