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Background: The aim of this study is to examine the association between adding-on (AO) and disc degeneration(DD) of distal unfused levels in Lenke 3 C, 5 C, 6 C adolescent idiopathic scoliosis (AIS) patients with a follow-up of at least two years by comparing preoperative and postoperative magnetic resonance imaging (MRI). Methods: 47 AIS patients (32 females and 15 males) with structural thoracolumbar/lumbar (TL/L) curves treated with long segment thoracolumbar fusion were retrospectively evaluated. Patients were divided into two groups according to the occurrence of the AO (AO and Non-AO groups). The unfused discs were graded using the MRI images according to the Pfirrmann grading method. The Scoliosis Research Society-22 (SRS-22) questionnaire and Visuel Analog Scale (VAS) were used to determine clinical outcomes. Results: The frequency of AO was found to be 29.78%. Postoperative total Pfirrmann score was significantly associated with AO. L5-S1 disc in the AO group had a statistically significant higher Pfirrmann grade than the Non-AO group. No significant association was found between the VAS and SRS-22 scores related to AO, DD or other radiological outcomes. Conclusion: Although patients with AO demonstrated higher postoperative Pfirmann scores, no impact on clinical scores was observed. Furthermore, patients with AO developed significantly higher DD in L5-S1 disc, even if it is not the segment adjacent to the fusion. L5-S1 disc, which is already susceptible to degeneration, was further compromised in the presence of AO. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to identify associated risk factors of distal adding-on phenomenon in Lenke 1A/B and 2A/B adolescent idiopathic scoliosis (AIS) patients and establish the corresponding prediction model. Methods: The clinical data of 119 Lenke 1A/B and 2A/B AIS patients were retrospectively analyzed. Preoperative, first erect (FE) radiographic parameters and radiographic parameters at the last follow-up were measured. Patients were divided into the adding-on group and the no adding-on group according to whether the adding-on phenomenon was observed at the last follow-up. Univariate analysis and multivariate logistic regression analysis were used to establish the corresponding prediction model. Results: Adding-on affected 39 (32.8%) patients at the last follow-up. Risser sign and 19 radiographic parameters showed significant differences between the two groups by univariate analysis. Stepwise logistic regression analysis found that the Risser sign and so on five predictor variable, and the nomogram was drawn. The calibration curve showed that the model fitted well. The area under the receiver operating characteristic (ROC) curve is 0.949. And the decision curve analysis curve model within the threshold range for interventions to improve clinical outcomes. There was no significant difference in SRS-22 scores between the two groups. Conclusions: This study established a prediction model with adding-on in Lenke 1A/B and 2A/B AIS patients. The nomogram contains five predictive variables, which can effectively predict the probability of adding-on phenomenon during follow-up, and may have greater clinical value for the treatment and prevention of adding-on phenomenon. [ABSTRACT FROM AUTHOR]

Abstract Background To evaluate the incidence and risk factors of postoperative distal adding-on in patients with Lenke 5C adolescent idiopathic scoliosis (AIS). More accurate selection criteria for the lower instrumented vertebra (LIV) should be confirmed to prevent distal adding-on. Methods Forty-six patients with Lenke 5C AIS who underwent posterior fusion were enrolled in the study. Patients were allocated into adding-on and no adding-on groups. Demographic data, clinical data, and radiographic parameters were recorded and compared. Results Postoperative distal adding-on occurred in eight patients (17.4%) during follow-up. Demographic data, clinical data, and baseline radiographic parameters of the two groups were not significantly different. The postoperative thoracolumbar (TL) or lumbar (L) Cobb angle, LIV translation, and LIV + 1 translation were higher in the adding-on group than those in the no adding-on group, while the postoperative coronal imbalance of the adding-on group was lower than that of the no adding-on group. The level difference of last barely touched vertebra (LBTV) and last substantial touched vertebra (LSTV) with LIV were higher in the adding-on group than in the no adding-on group. Conclusion Postoperative TL/L curve, postoperative LIV translation, postoperative LIV + 1 translation, and postoperative coronal imbalance were determined as risk factors for postoperative distal adding-on in patients with Lenke 5C AIS. Moreover, LIV selection of LBTV-1 or LSTV-1 may cause a higher risk of postoperative distal adding-on.

Objective To determine whether the last touched vertebra (LTV) on supine radiographs is suitable for the lower instrumented vertebra (LIV) in adolescent idiopathic scoliosis (AIS) correction surgery. Methods In total, 57 patients were included in the study following posterior instrumentation and fusion. The average follow-up period was 2.2 years. Patients were classified into 4 groups according to the relationship of the location of LIV, LTV, and the last substantially touched vertebra (LSTV) on upright radiographs and the LTV on supine radiographs. In group 1, the upright LTV and supine LTV were the same. Group 1 was subdivided into group 1A and group 1B according to whether the LTV and LSTV were different or the same, respectively. In group 2, the upright LTV was selected as the LIV, whereas in group 3, the supine LTV was selected as the LIV. The baseline characteristics and the preoperative and postoperative radiographic/clinical outcomes of the groups were analyzed. Results No differences were found in the preoperative clinical and radiographic baseline characteristics of the 4 groups except the LIV-central sacral vertical line distance. The immediate, 6-month, 1-year, and 2-year postoperative outcomes were not significantly different among the 4 groups. One patient (4.3%) in group 1A experienced radiographic adding-on without clinical symptoms. No patients underwent revision surgery. Conclusion The group in whom the LIV was selected as the LTV on supine x-rays showed similar postoperative radiographic and clinical results to other groups. The LTV on preoperative supine radiographs is acceptable as the LIV in AIS surgery to maximize motion segments.

Objective To compare and identify risk factors for distal adding-on (AO) or distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS) treated by anterior- (ASF) and posterior spinal fusion (PSF) to L3. Methods AIS patients undergoing ASF versus PSF to L3 from 2000–2010 were analyzed. Distal AO and DJK were deemed poor radiographic results. New stable (SV) and neutral vertebra (NV) scores were defined for this study. The total stability (TS) score was the sum of the SV and NV scores. Results Twenty of 42 (ASF group: 47.6%) and 8 of 72 patients (PSF group: 11.1%) showed poor radiographic outcome. Fused vertebrae, correction rate of main curve, coronal reduction rate of L3 were significantly higher in PSF group. Multiple logistic regression results indicated that preoperative SV-3 at L3 in standing and side benders (odds ratio [OR], 2.7 and 3.7, respectively), TS score -5, -6 at L3 (OR, 4.9), rigid disc at L3–4 (OR, 3.7), lowest instrumented vertebra (LIV) rotation > 15° (OR, 3.3), LIV deviation > 2 cm from center sacral vertical line (OR, 3.1) and ASF (OR, 13.4; p

Background: To evaluate the incidence and risk factors of postoperative distal adding-on in patients with Lenke 5C adolescent idiopathic scoliosis (AIS). More accurate selection criteria for the lower instrumented vertebra (LIV) should be confirmed to prevent distal adding-on.Methods: Forty-six patients with Lenke 5C AIS who underwent posterior fusion were enrolled in the study. Patients were allocated into adding-on and no adding-on groups. Demographic data, clinical data, and radiographic parameters were recorded and compared.Results: Postoperative distal adding-on occurred in eight patients (17.4%) during follow-up. Demographic data, clinical data, and baseline radiographic parameters of the two groups were not significantly different. The postoperative thoracolumbar (TL) or lumbar (L) Cobb angle, LIV translation, and LIV + 1 translation were higher in the adding-on group than those in the no adding-on group, while the postoperative coronal imbalance of the adding-on group was lower than that of the no adding-on group. The level difference of last barely touched vertebra (LBTV) and last substantial touched vertebra (LSTV) with LIV were higher in the adding-on group than in the no adding-on group.Conclusion: Postoperative TL/L curve, postoperative LIV translation, postoperative LIV + 1 translation, and postoperative coronal imbalance were determined as risk factors for postoperative distal adding-on in patients with Lenke 5C AIS. Moreover, LIV selection of LBTV-1 or LSTV-1 may cause a higher risk of postoperative distal adding-on. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective study.Objective: To determine in which case one level proximal to last substantially touching vertebra (LSTV-1) could be a valid lowest instrumented vertebra (LIV), in which case distal fusion should extend to last substantially touching vertebra (LSTV), and to identify risk factors for distal adding-on.Summary Of Background Data: Posterior thoracic fusion to save more lumbar mobile segments has become the mainstay of operative treatment for adolescent idiopathic scoliosis (AIS) with Lenke 1A/2A curves. Although previous studies have recommended selecting the LSTV as LIV, good outcomes could still be achieved in some cases when LSTV-1 was selected as LIV.Methods: Ninety-four patients were included in the study with a minimum of 2-year follow-up after posterior thoracic instrumentation, in which LSTV-1 was selected as LIV. Patients were identified with distal adding-on between first erect radiographs and 2-year follow-up based on previously defined parameters. Factors associated with the incidence of adding-on were analyzed.Results: The mean follow-up duration was 37.7 ± 15.8 months. Forty patients (42.6%) with LSTV-1 selected as LIV achieved good outcomes at the last follow-up. Several preoperative risk factors significantly associated with distal adding-on were identified, including lower Risser (P = 0.001), longer thoracic curve length (P = 0.005), larger rotation and deviation of LSTV-1 (P  < 0.001), and preoperative coronal imbalance (P = 0.013).Conclusion: Skeletally immature patients with long thoracic curve, preoperative coronal imbalance, large rotation, and deviation of LSTV-1 are at increased risk of distal adding-on when selecting LSTV-1 as LIV. Under this condition, distal fusion level should extend to LSTV; while in other case, LSTV-1 could be a valid LIV.Level of Evidence: 4. [ABSTRACT FROM AUTHOR]

Introduction: SHILLA and growth rods are two main surgical correction techniques for patients with early-onset scoliosis. There have been some comparative studies between the two techniques, where a comparison was made between deformity identifying characteristics such as Cobb angle, apical vertebral translation, coronal balance, spinal length gain, etc. However, the SHILLA procedure experiences loss of correction or the reappearance of deformity through crankshafting or adding-on (e.g., distal migration). The current study identifies a solution with a modified approach to SHILLA (which could help in dynamically remodulating the apex of the deformity and mitigating loss of correction) and presents comparative correction data against the long-established traditional growth rod system. Methods: The active apex correction (APC) group consisted of 20 patients and the growth rod group consisted of 26 patients, both with the same inclusion and exclusion criteria. The APC surgical procedure involved a modified SHILLA technique, that is, insertion of pedicle screws in the convex side of the vertebrae above and below the wedged one for compression and absence of apical fusion. Results: There were no statistical differences between the various spinal parameters (namely, Cobb angle, apical vertebral translation, sagittal balance, and spinal length gain) of the two groups. However, significant differences existed for coronal balance, which in part may have been due to differences in its pre-op value between the two groups. Conclusions: APC and the traditional growth rod system showed similar deformity correction parameters at current follow-ups; however, the latter requires multiple surgeries to regularly distract the spine.

This section of the symposium brings to the reader seven case scenarios with regard to adolescent idiopathic scoliosis (AIS). These are the common curve patterns which a spine surgeon encounters in his practice. They have been contributed by different spine surgeons and highlight the varied approaches taken by them to achieve a satisfactory outcome. Each scenario highlights the proper workup required for such cases along with planning of the levels of fusion.

Objective: The purpose of this study was to identify risk factors for distal adding on (AO) or distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS) treated by posterior spinal fusion (PSF) to L3 with a minimum 2-year follow-up. Methods: AIS patients undergoing PSF to L3 by two senior surgeons from 2000-2010 were analyzed. Distal AO and DJK were deemed poor radiographic results and defined as >3 cm of deviation from L3 to the center sacral vertical line (CSVL), or >10° angle at L3-4 on the posterior anterior- or lateral X-ray at ultimate follow-up. New stable vertebra (SV) and neutral vertebra (NV) scores were defined for this study. The total stability (TS) score was the sum of the SV and NV scores. Results: Ten of 76 patients (13.1%) were included in the poor radiographic outcome group. The other 66 patients were included in the good radiographic outcome group. Lower Risser grade, more SV-3 (CSVL doesn't touch the lowest instrumented vertebra [LIV]) on standing and side bending films, lesser NV and TS score, rigid L3-4 disc, more rotation and deviation of L3 were identified risk factors for AO or DJK. Age, number of fused vertebrae, curve correction, preoperative coronal/sagittal L3-4 disc angle did not differ significantly between the two groups. Multiple logistic regression results indicated that preoperative Risser grade 0, 1 (odds ratio [OR], 1.8), SV-3 at L3 in standing and side benders (OR, 2.1 and 2.8, respectively), TS score -5, -6 at L3 (OR, 4.4), rigid disc at L3-4 (OR, 3.1), LIV rotation >15° (OR, 2.9), and LIV deviation >2 cm from CSVL (OR, 2.2) were independent predictive factors. Although there was significant improvement of the of Scoliosis Research Society-22 average scores only in the good radiographic outcome group, there was no significant difference in the scores between the groups. Conclusion: The prevalence of AO or DJK at ultimate follow-up for AIS with LIV at L3 was 13.1%. To prevent AO or DJK following fusion to L3, we recommend that the CSVL touch L3 in both standing and side bending, TS score is -4 or less, the L3/4 disc is flexible, L3 is neutral (<15°) and ≤2 cm from the midline and the patient is ≥ Risser 2. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective study.Objective: The aim of this study was to investigate the incidence and risk factors for distal adding-on (AO) phenomenon after posterior spinal fusion (PSF) in scoliosis secondary to Chiari malformation type I (CMS) patients with right major thoracic curve.Summary Of Background Data: Distal AO phenomenon is a common complication observed in adolescent idiopathic scoliosis (AIS), which is significantly associated with unsatisfactory outcomes. However, few studies specifically focused on the incidence and risk factors of distal AO in CMS.Methods: Seventy-eight CMS adolescents were included with a minimum of 2-year follow-up after PSF. patients with distal AO at the final follow-up were divided into AO group and those without were No-AO group. The coronal and sagittal parameters were evaluated preoperatively, immediately after surgery, and at the last follow-up. Clinical outcome was analyzed using the Chicago Chiari Outcome Scale (CCOS).Results: Distal AO was observed in 18 of 78 patients (23.1%). Compared with No-AO group, patients with distal AO had significantly lower Risser sign (P = 0.001), more flexibility of lumbar curve (P = 0.021), higher incidence of lowest instrumented vertebra-last substantially touched vertebra (LIV-LSTV) ≤0 (P = 0.001), smaller postoperative Cobb angle of lumbar curve (P < 0.001), and greater correction rate of lumbar curve (P = 0.001). Logistic regression analysis revealed that low Risser sign (Grade 1-2, odds ratio [OR] = 5.7, P = 0.029) and LIV-LSTV ≤0 (OR = 6.4, P = 0.019) were independent risk factors for distal AO. There was no significant difference of CCOS scores between two groups at the final follow-up (P > 0.05 for all).Conclusion: The incidence of distal AO was 23.1% in CMS patients after PSF. Patients with low Risser sign and LIV-LSTV ≤0 were high risk factors for distal AO.Level of Evidence: 3. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective cohort study.Objective: This study aimed to identify risk factors that predict lumbar curve adding-on in patients who had selective thoracic fusion.Summary Of Background Data: Selective thoracic fusion offers deformity correction of Lenke 1 and 2 thoracic curves and maintains lumbar range of movement. However, some patients may develop postoperative lumbar adding-on.Methods: This study included patients 18 years or younger that underwent spinal instrumentation for Lenke 1 and 2 curves.Results: A total of 161 patients were included (147 females, 14 males). The mean age was 14.0 ± 2.1 years: 103 patients were Lenke 1, and 58 patients were Lenke 2 curves. Ninety-seven patients underwent posterior approach surgery, whereas 64 via anterior approach. In the posterior approach group, 79(81.4%) patients underwent selective fusion. Ten patients (6.2%) had lumbar curve adding-on, with nine females and one male. There were seven Lenke 1 and three Lenke 2 patients. All 10 patients were lumbar modifier (a), with 5 hypokyphotic patients. Selective fusion was done in nine patients. Lumbar adding-on was seen most commonly between 6 months to 1 year postoperative period (five patients). Two patients had adding-on because of incorrect distal fusion level, six were due to 1A-R curve, one due to the inadvertent fusion from the excessive long rod at the subjacent level. In multivariate analysis, hypokyphotic patients were at higher risk of lumbar adding-on (odds ratio = 9.2). Patients with Risser classification 0, 1, 2, 3 were also at higher risk of lumbar adding-on (odds ratio =6.1).Conclusion: The incidence of lumbar curve adding-on was 6.2%. Patients who were hypokyphotic and skeletally immature are nine times and six times more likely to have lumbar adding-on, respectively. This article examines adding-on in patients who had either anterior or posterior approach scoliosis surgeries, with follow-up stretching up to 10 years. This offers the rare opportunity to examine the natural history of the adding-on phenomenon.Level of Evidence: 3. [ABSTRACT FROM AUTHOR]

Provide current overview of Active Apex correction as a new technique for surgical management for Early Onset Scoliosis by dynamically remodulating the apex of the deformity and mitigate loss of correction and presents a comparative correction data against the long-established systems. Summary of the surgical technique and review of the existing retrospective data on APC surgical technique and its comparison against other existing techniques. Retrospective clinical results showed the efficiency of the APC technique in active remodulation of the apex of the curve with lower incidence of implant related complications in comparison to SHILLA and Magnetically Controlled Growing Rods (MCGR). APC also showed similar results with traditional growing rods without the need for repeated distraction surgeries for 4 year s. Active Apex Control is safe and viable option in surgical management for Early Onset Scoliosis patients even in areas with limited resources. [ABSTRACT FROM AUTHOR]

Hypothesis: Fusing shorter than the last touched vertebra (LTV) is a safe approach in flexible main thoracic (MT) adolescent idiopathic scoliosis (AIS) curves. Methods: This was a prospective study on consecutive AIS patients surgically treated with selective fusion of the MT curve. Fusion-level selection was based on the fulcrum-bending radiograph method. Patients were grouped based on the position of the lowest instrumented vertebra as proximal to the LTV (proxLTV, n = 43), at the LTV (atLTV, n = 45), and distal to the LTV (distLTV, n = 21). Results: A total of 109 patients were included in the study. Preoperatively, the distLTV group had greater lumbar Cobb angle, lumbar apical translation, and less flexibility in the MT curve. At 2-year follow-up, the groups did not differ in MT curve correction, but the distLTV had larger lumbar Cobb angle, more apical translation, and worse coronal balance. Distal adding-on was observed in 11 patients (26%) in the proxLTV group, four patients (9%) in the atLTV group, and one patient (5%) in the distLTV group (p = 0.031). Adding-on was associated with younger patients and lower Risser grade at the time of surgery but not with any other radiographic parameter. No differences in SRS-22r scores were observed between the groups. Conclusions: Proximal fusion carries the risk of adding-on, but leaving unfused segments in the lower spine increases the potential for compensatory mechanisms to improve spinal and truncal balance. In mature patients with a flexible MT curve, surgeons may consider fusion at or cranial to the LTV. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether the rotation of preoperative-presumed lowest instrumented vertebra (LIV) is a risk factor for adding-on (AO) in adolescent idiopathic scoliosis (AIS) treated with selective posterior thoracic fusion (sPTF). Methods: A total of 196 AIS patients of Lenke type 1A or 2A with minimum 2-year follow-up after sPTF with all pedicle screw instrumentation were included. Radiographical parameters were measured as follows: preoperative rotation angle of presumed LIV and LIV + 1, LIV + 1/LIV rotation difference, postoperative rotation angle of LIV and LIV derotation angle on CT scans. Patients were classified into AO group and non-AO group during the follow-up. The parameters were compared between the two groups to investigate risk factors for AO. Results: Among 196 patients, 40 (20.4%) patients developed with AO at the final follow-up. Compared with non-AO group, patients with AO had significantly larger preoperative rotation angle of presumed LIV (8.8° ± 3.4° vs. 3.4° ± 2.9°, P < 0.001) and LIV + 1 (5.9° ± 4.0° vs. 3.6° ± 2.9°, P = 0.004), LIV + 1/LIV rotation difference (− 2.6° ± 3.7° vs. 0.6° ± 3.2°, P < 0.001) and postoperative rotation angle of LIV (7.2° ± 4.3° vs. 3.0° ± 2.9°, P < 0.001). The last substantially touched vertebrae (LSTV) was selected as LIV in 148 patients, among which the above described parameters were found to be remarkably larger in AO group than non-AO group as well. Multivariate analysis presented Risser grade and preoperative rotation angle of presumed LIV as independent predictors of AO. Conclusion: AIS patients with low Risser grade and large preoperative rotation angle of presumed LIV are more likely to develop with AO after sPTF. Moreover, for the patients with LSTV selected as LIV, preoperative rotation of presumed LIV might be still a risk factor associated with the occurrence of AO. Level of Evidence: III These slides can be retrieved under Electronic Supplementary Material. [ABSTRACT FROM AUTHOR]

Objective. To analyze the incidence of adding-on phenomenon in the surgery of Lenke type 1 idiopathic scoliosis. Material and Methods. The study included prospective analysis of radiographs of 89 patients (82 females and 7 males) with idiopathic scoliosis who met the criteria for inclusion. The age of patients at the time of surgery ranged from 12 to 25 years (mean: 16.3 ± 4.4 years). The average follow-up period was 2.3 ± 0.4 years. Scoliotic deformity corresponded to grade III according to V.D. Chaklin’s classification in 24 patients, and to grade IV in 65. The magnitude of the primary thoracic curve varied from 30° to 103° of Cobb angle (mean: 61.1° ± 17.1°). In all cases, segmental third generation instrumentation (hybrid or laminar) was used in combination with intraoperative skeletal traction with an afford equal to 50 % of the patient’s body weight. Laminar fixation was used in 6 patients, and hybrid fixation with different extent of screw installation in 83. Results. The following parameters showed significant increase: the magnitude of thoracic curve according to Cobb – 16.0° ± 4.3°, the distance from the center of the vertebra located one level distal to the lowest instrumented vertebra, to the central sacral vertical line (LIV+1- CSVL) – 3.6 ± 2.5 mm, the tilt of the lower instrumented vertebra in the coronal plane (LIV tilt angle) – 3.6° ± 2.8°, the tilt of the ver- tebra located one level distal to the lowest instrumented vertebra (LIV+1 tilt angle) – 4.6° ± 2.5°, and the distance from the center of the apical vertebra of the primary curve to the central sacral vertical line (AV-CSVL) – 17.2 ± 12.0 mm. A significant correlation was found between postoperative magnitude of the scoliotic curve and AV-CSVL distance, postoperative LIV+1-CSVL distance and postoperative LIV+1 tilt angle. An increase in LIV+1 tilt angle in combination with an increase in LIV+1-CSVL distance by more than 4 mm (or degrees) could be a parameter for measuring the adding-on phenomenon. Conclusion. The indication for reoperation may probably be a significant tilt of the vertebra located below the lowest instrumented vertebra, accompanied by pain syndrome and coronal imbalance.

Study Design: A retrospective study.Objective: The aim of this study was to determine whether the last substantially touching vertebra (LSTV) can be selected as the optimal lowest instrumented vertebra (LIV) for Lenke 2A adolescent idiopathic scoliosis (AIS) with different lumbar modifiers (2A-R and 2A-L) and to investigate its relationship with the distal adding-on.Summary Of Background Data: Previous studies have documented good outcomes in Lenke 1A curve when LSTV was selected as LIV.Methods: A total of 101 female patients were included with a minimum of 2-year follow-up after selective posterior surgery. Patients were classified on the basis of the direction of L4 tilt: 2A-L and 2A-R. Patients with LSTV-1, LSTV, or LSTV+1 selected as LIV were assigned to three groups. Factors associated with adding-on were analyzed through comparison among the three groups.Results: The level of LSTV was more distal in the 2A-R group than that in the 2A-L group (P = 0.011). Distal adding-on was observed in 24 patients (23.8%). In the 2A-R curves, 26.1% patients were found to have adding-on. The incidence of adding-on was significantly higher in LSTV-1 than LSTV or LSTV+1 group. Logistic regression analysis showed the distance between LIV and LSTV (LIV-LSTV <0) was the independent factor associated with adding-on (odds ratio [OR] = 8.7, 95% confidence interval [CI] = 3.1-45.5, P = 0.011). In the 2A-L curves, 21.8% patients were found to have adding-on. The incidence of adding-on was significantly lower in LSTV+1 than LSTV-1 or LSTV group. Similarly, logistic regression showed the distance between LIV and LSTV (LIV-LSTV ≤0) had significant association with adding-on (OR = 11.9, 95% CI = 2.5-53.2, P = 0.009).Conclusion: The distance between LIV and LSTV was a significant factor associated with adding-on for both 2A-R and 2A-L patients. The rule of selecting LIV should be different between 2A-R and 2A-L curves. We recommend to extend the fusion level to LSTV in 2A-R curve and to LSTV+1 in 2A-L curve to avoid distal adding-on.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective study with prospective radiographic data collection.Objective: To compare fusion level determination criteria using the fulcrum bending radiograph (FBR) and the last substantially touched vertebra (STV) as the lowest instrumented vertebra (LIV) in the radiographic outcomes of correction surgery for Lenke 1A and 2A scoliosis patients with a minimum of 2-year follow-up.Summary Of Background Data: The STV has been proposed as the LIV in Lenke 1A and 2A curves to avoid postoperative distal adding-on. However, the influence of the inherent flexibility of the curves on selecting the LIV in relation to the STV is not known.Methods: A total of 65 consecutive Lenke 1A and 2A patients who underwent posterior selective thoracic fusion were included in this study with a minimum of 2-year follow-up. LIV determination was compared with the FBR and STV methods. The curve correction, trunk shift, radiographic shoulder height, list, and the incidence of distal adding-on were documented.Results: Mean preoperative, postoperative, and final follow-up standing coronal Cobb angles of primary curves were 59.37°, 15.58°, and 16.62° respectively. Using the FBR to determine the LIV, STV was selected in 16 patients (25%), STV-1 in 34 (52%), STV-2 in 11 (17%), and STV-3 in three (5%). Fusion level difference between using FBR and STV method was statistically significantly larger (P = 0.019) in patients with more than 70% fulcrum flexibility (mean: 1.18 levels, range: 0-3 levels) than those with less than or equal to 70% flexibility (mean: 0.70 level, range: -1 to 3 levels). Mean fulcrum flexibility was 73.9% in patients who achieved a shorter fusion by FBR method and 66.3% in patients who did not achieve a shorter fusion. Adding-on was observed in three patients (4.6%).Conclusion: By considering the curve flexibility, LIV determination using FBR method achieved a shorter fusion than STV method in over 70% of Lenke 1A and 2A patients, while being safe and effective at 2-year follow-up.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

To analyze the effects of direct vertebral rotation (DVR) on radiologic outcomes in the treatment of thoracic adolescent idiopathic scoliosis after selective thoracic fusion with pedicle screw instrumentation. Adolescent idiopathic scoliosis patients with single thoracic curves (n = 110) treated by selective thoracic fusion with a minimum of 2 years of follow-up were retrospectively analyzed. The patients were separated into 2 groups: non-DVR (n = 63) and DVR (n = 47). There was a significant difference in fused segments between the non-DVR and DVR groups (P < 0.001). There was also a significant difference in main thoracic curve postoperatively (P = 0.001) and at the last follow-up (P = 0.006) between the non-DVR and DVR groups. However, there was no significant difference in proximal thoracic and lumbar curves postoperatively (proximal thoracic curve: P = 0.186; lumbar curve: P = 0.155) and at the last follow-up (proximal thoracic curve: P = 0.250; lumbar curve: P = 0.060) between the 2 groups. Significant improvements in the lowest instrumented vertebra tilt and disc angle were noted but then slight deteriorations in such were observed during the follow-up period in the non-DVR group. The prevalence of unsatisfactory results was 20.6% (13 of 63) in the non-DVR group and 19.1% (9 of 47) in the DVR group, with no significant difference (P = 0.522). For correcting single thoracic adolescent idiopathic scoliosis by selective thoracic fusion with pedicle screw instrumentation, the addition of DVR to the surgical procedure showed comparable radiologic outcomes compared with non-DVR procedures. [ABSTRACT FROM AUTHOR]

Background Context: In Lenke 1C and 2C curves, the choice between selective thoracic fusion (STF) versus non-selective thoracic fusion as the optimal surgical treatment is controversial.Objective: This study aimed to assess the radiological and clinical outcome of patients with Lenke 1C and 2C curves treated with STF.Study Design: This is a retrospective study.Patient Sample: A total of 44 patients comprised the study sample.Methods: Forty-four patients with Lenke 1C and 2C curves with adolescent idiopathic scoliosis who underwent STF were reviewed. Radiological parameters and Scoliosis Research Society (SRS)-22r scores were assessed preoperatively, postoperatively, and on final follow-up. The incidence of coronal decompensation, lumbar decompensation, and adding-on phenomenon were reported.Results: Mean follow-up duration was 45.1±12.3 months and mean age was 17.0±5.1 years. The preoperative middle thoracic and thoracolumbar/lumbar (MT:TL/L) Cobb angle ratio was 1.4±0.3 and the MT:TL/L apical vertebra translation (AVT) ratio was 1.6±0.8. Final follow-up coronal balance was -13.0±11.5 mm, main thoracic AVT was 6.9±11.8 mm, and lumbar AVT was -20.4±13.8 mm (p<.05). Lumbar Cobb angle improved from 47.5°±7.8° to 24.9°±8.2° after operation and 23.3°±9.8° at final follow-up. The spontaneous lumbar curve correction rate was 50.9%. There were 9 patients (20.5%) who had coronal decompensation, 4 patients (9.1%) who had lumbar decompensation, and 11 patients (25.0%) who had adding-on phenomenon. We did not perform any revision surgery. The SRS-22r scores improved significantly in the overall scores, self-image, and mental health domain.Conclusions: Selective thoracic fusion led to improvement in the radiological and clinical outcome for patients with Lenke 1C and 2C. Although no patients required revision surgery, the rate of coronal decompensation, lumbar decompensation, and adding-on phenomenon are significant. [ABSTRACT FROM AUTHOR]

Study Design: A systematic review and meta-analysis.Objective: To discuss the prevalence, risk factors, and characteristics of the "adding-on" phenomenon in idiopathic scoliosis (IS).Summary Of Background Data: There are controversies on the prevalence and risk factors of the "adding-on" phenomenon. In addition, there is no comprehensive study to describe the characteristics of "adding-on" in IS patients.Methods: We performed a systematic online search using PubMed, EMBASE, Web of Science, the Cochrane Library, and China WeiPu Library to identify eligible studies. Effect size (ES), odds ratios (OR), and weight mean difference (WMD) with 95% confidence interval (CI) were used to evaluate the incidence, characteristics, and risk factors for "adding-on," respectively.Results: The overall pooled prevalence of "adding-on" was 14%. Subgroup analysis showed that the prevalence of "adding-on" in Lenke 1A adolescent idiopathic scoliosis (AIS), Lenke 2 AIS, Lenke 5 AIS, and mixed AIS was 15%, 12%, 9%, and 16%, respectively. AIS patients with the "adding-on" phenomenon had smaller proximal thoracic curve (PTC), main thoracic curve (MTC), clavicle angle, T1 tilt angle and radiographic shoulder height (RSH), and larger correction of PTC. Age, Risser sign, preoperative PTC, preoperative MTC, preoperative lumbar curve (LC), preoperative coronal balance and sagittal balance, and T4 tile were identified as risk factors of "adding-on." Selection of lower instrumented vertebra (LIV) was also an important risk factor as LIV-Center Sacral Vertical Line (CSVL), LIV-end vertebra, LIV-Stable Vertebra, and LIV-Neutral vertebra, and deviation of LIV+1 was found to be significantly associated with "adding-on." Besides, postoperative MTC was also significantly different between patients with and without "adding-on."Conclusion: The pooled prevalence varied differently in different types of IS. Patients with "adding-on" had smaller PTC, MTC, angle, T1 tilt angle and RSH, and larger correction of PTC. Younger age, less skeletal maturity, smaller preoperative PTC, smaller preoperative MTC, smaller preoperative LC, larger preoperative coronal, sagittal imbalance, selection of LIV, and overcorrection of coronal and sagittal alignment were risk factors for "adding-on."Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective comparative study.Objective: The aim of this study was to analyze the exact distal fusion level in the treatment of major thoracolumbar and lumbar (TL/L) adolescent idiopathic scoliosis (AIS) using rod derotation (RD) and direct vertebral rotation (DVR) following pedicle screw instrumentation (PSI).Summary Of Background Data: Proper determination of distal fusion level is a very important factor in deformity correction and preservation of motion segments in the treatment of major TL/L AIS.Methods: AIS patients with major TL/L curves (n = 64) treated by PSI with RD and DVR methods with a minimum 2-year follow-up were divided into AL3 (flexible) and BL3 (rigid) according to the flexibility and rotation by preoperative bending radiographs.Results: There was no significant difference in TL/L (major) curve between the AL3 and BL3 groups postoperatively (P = 0.933) and at the last follow-up (P = 0.144). In addition, there was no significant difference in thoracic (minor) and compensatory (caudal) curve postoperatively (thoracic curve: P = 0.828, compensatory curve: P = 0.976); however, there was a significant difference in compensatory (caudal) curve at the last follow-up (P = 0.041). The overall prevalence of unsatisfactory results was 28.1% (18/64 patients), and the prevalence was 15.2% (7/46) in the AL3 group and 61.1% (11/18) in the BL3 group, which was significantly different (P < 0.05).Conclusion: Lowest instrumented vertebra (LIV) would be selected at L3 (EV) when the curve is flexible; L3 crosses CSVL with a rotation of less than grade II in preoperative bending radiographs. However, if the curve is rigid, LIV should be extended to L4 (EV + 1) in order to prevent the adding-on phenomenon in the treatment of major TL/L AIS using RD and DVR following PSI.Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Background Context Shoulder imbalance, coronal decompensation, and adding-on phenomenon following corrective surgery in patients with adolescent idiopathic scoliosis are known to be related to the fusion level selected. Although many studies have assessed the appropriate selection of the proximal and distal fusion level, no definite conclusions have been drawn thus far. Purpose We aimed to assess the problems with fusion level selection for corrective surgery in patients with adolescent idiopathic scoliosis, and to enhance understanding about these problems. Study Design This study is a narrative review. Methods We conducted a literature search of fusion level selection in corrective surgery for adolescent idiopathic scoliosis. Accordingly, we selected and reviewed five debatable topics related to fusion level selection: (1) selective thoracic fusion; (2) selective thoracolumbar-lumbar (TL-L) fusion; (3) adding-on phenomenon; (4) distal fusion level selection for major TL-L curves; and (5) proximal fusion level selection and shoulder imbalance. Results Selective fusion can be chosen in specific curve types, although there is a risk of coronal decompensation or adding-on phenomenon. Generally, wider indications for selective fusions are usually associated with more frequent complications. Despite the determination of several indications for selective fusion to avoid such complications, no clear guidelines have been established. Although authors have suggested various criteria to prevent the adding-on phenomenon, no consensus has been reached on the appropriate selection of lower instrumented vertebra. The fusion level selection for major TL-L curves primarily focuses on whether distal fusion can terminate at L3, a topic that remains unclear. Furthermore, because of the presence of several related factors and complications, proximal level selection and shoulder imbalance has been constantly debated and remains controversial from its etiology to its prevention. Conclusions Although several difficult problems in the diagnosis and treatment of adolescent idiopathic scoliosis have been resolved by understanding its mechanism and via technical advancement, no definite guideline for fusion level selection has been established. A review of five major controversial issues about fusion level selection could provide better understanding of adolescent idiopathic scoliosis. We believe that a thorough validation study of the abovementioned controversial issues can help address them. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective study.Objective: To compare the long-term outcomes of correction surgery for Lenke 1A scoliosis patients among those with non-Substantially Touched Vertebra (nSTV), nSTV+1, or STV selected as lowest instrumented vertebra (LIV).Summary Of Background Data: Previous studies have documented good outcomes when last touching vertebra (LTV) was selected as LIV; however, it is sometimes confusing to determine the proper LTV when central sacral vertical line (CSVL) slightly touches the vertebra.Methods: A total of 104 patients were included in the study with a minimum of 2-year follow-up after selective posterior thoracic instrumentation. STV was defined as the LTV where CSVL was between the pedicles or touching the pedicle. nSTV was defined as the LTV where CSVL was touching the corner of the vertebra lateral to the pedicle border. Patients with nSTV, nSTV+1, or STV selected as LIV were assigned to three groups with clinical outcomes compared among them. Factors associated with the incidence of adding-on were analyzed.Results: Distal adding-on was observed in 23 patients (22.1%). The incidence of distal adding-on was significantly higher in nSTV group than STV group or nSTV+1 group. Several risk factors significantly associated with adding-on were identified, including the distance between LIV and STV/nSTV+1, preoperative proximal thoracic curve and sagittal vertical axis, postoperative lumbar lordosis, apical translation, trunk shift, and radiographical shoulder height. Logistic regression analysis showed that the distance between LIV and STV/nSTV+1 (LIV-STV <0 or LIV-(nSTV+1) <0) was the only independent factor associated with the incidence of adding-on (odds ratio = 27.1, 95% confidence interval = 2.3-311.2, P = 0.002).Conclusion: Differentiating STV from nSTV properly can facilitate the determination of optimal LIV and decrease the incidence of distal adding-on. Selecting STV or nSTV+1 as LIV could yield a promising outcome for Lenke 1A scoliosis patients undergoing selective posterior thoracic fusion.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective comparative study.Objective: We compared the outcomes between patients treated either by selective thoracic anterior (ASF) or posterior spinal fusion (PSF), with a minimum 10-year follow-up.Summary Of Background Data: A retrospective long-term follow-up study was conducted to compare PSF (P group) and ASF (A group) with Lenke type 1 or 2. There were no significant differences in the correction rate and incidence of degenerative discs (DDs) on the lumbar area. Loss of correction was greater in the A group.Methods: The inclusion criteria were female, AIS Lenke type 1 or 2, minimum 10-year follow-up, MRI check-up at 5 years and 10 years postop. The number of patients, age, and curve types at the time of surgery were matched in both groups. Complications, pulmonary function, and SRS-30 were also evaluated.Results: P group: adding-on (AO) occurred in 14 patients. Two patients demonstrated progression of scoliosis >5° during follow-up. Degenerative discs occurred in 43% of patients at 10 years postop. There were significant differences in the %VC and FVC before surgery and at the final visit (P < 0.05). A group: AO occurred in 16 patients. Eleven showed progression of scoliosis >5°. Degenerative disc was recognized in 53% of the patients. There was no significant difference in the pulmonary function. There was a significant difference in selfimage score in the SRS-30 between the two groups (P < 0.05).Conclusion: Correction of scoliosis was significantly better ASF than PSF immediately postop. Greater loss of correction occurred with ASF at postop 10 years. Although shorter segments could be fused by ASF, there was no significant difference in the incidence of DDs. Pulmonary function test results improved in the P group and were restored in the A group during the perioperative period. [ABSTRACT FROM AUTHOR]

The article presents research which examined the etiology and factors contributing to postoperative adding-on in Lenke type 1A curve. Researchers observed the health conditions of 112 patients after undergoing selective posterior thoracic fusion for Lenke type 1A curve. They found that surgeons should attain the maximum reduction of the apical translation of the main thoracic curve to avoid distal adding-on after the procedure.

The article discusses a study on the parameters for distal adding-on, a significant issue in the management of Lenke 1A scoliosis. Lenke 1A scoliosis is a common type of adolescent scoliosis and distal adding-on may manifest itself after surgical treatment as an increase in Cobb angle, vertebral translation or vertebral rotation. The researchers observed that lowest instrumented vertebra-center sacral vertical line (LIV-CSVL) distance is an ideal parameter to measure distal adding-on.

This article discusses a study on risk factors for the presence of distal adding-on in Lenke 1A scoliosis. The study shows that the selection of lowest instrumented vertebra (LIV) is correlated with the presence of adding-on in Lenke 1A type scoliosis. It concludes that choosing the first vertebra in cephalad direction from sacrum as LIV is the best treatment strategy as it can prevent distal adding-on and can save more lumbar motion and growth potential.