Search

Study Design: A retrospective cohort study., Objective: To evaluate long-term rotational changes in the vertebrae of patients with adolescent idiopathic scoliosis (AIS) who underwent direct vertebral rotation (DVR)., Summary of Background Data: DVR using thoracic pedicle screws, a rotational corrective maneuver used in the surgical treatment of AIS, was introduced in 2004. Although DVR is considered to be the main axial corrective maneuver, the long-term rotational changes of vertebrae following this treatment are not well understood., Materials and Methods: A total of 135 vertebrae that underwent DVR using thoracic pedicle screws with a minimum five-year follow-up were retrospectively assessed for the vertebral rotation angle. The vertebral rotation of the apical vertebra (AV) and distal end vertebra (EV) was evaluated using the Nash-Moe scale, the rotational angle to the sacrum (RAsac), and the Aaro and Dahlborn method. The Student t test (paired means) was used for continuous variables, and the χ 2 test was used for categorical variables, as appropriate. A comparison of two and three groups used a one-way repeated measures analysis of variance, and the post hoc analysis used the Bonferroni test., Results: The mean Nash-Moe scale of distal EV showed statistically significant differences between preoperative and postoperative values ( P =0.034) and no statistically significant difference between postoperative and last follow-up values ( P =1.000). The last follow-up RAsac of AV did not differ significantly from the preoperative RAsac of AV ( P =0.515). The last follow-up RAsac of distal EV was significantly lower than the preoperative RAsac of distal EV ( P =0.001). The Pearson correlation analysis showed that the last follow-up RAsac of distal EV was correlated with the Cobb angle of the main curve ( r =0.459, P =0.004), loss of correction ( r =0.541, P =0.001), and lowest instrumented vertebra tilt angle ( r =0.504, P =0.001)., Conclusions: The rotation regression phenomenon in AV and rotation maintenance in distal EV were observed after DVR over an average 10-year follow-up. These findings suggest that the DVR in the surgical treatment of AIS has a positive long-term effect on the stabilization of distal EV from the point of view of axial rotation., Level of Evidence: 4., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: There is great controversy about the etiologic origin of adolescent idiopathic scoliosis. Multiple theories have been suggested, including metabolic aspects, endocrine dysfunction, neurological central abnormalities, genetic predisposition and epigenetic factors involved in the development of scoliosis. However, there has always been speculations based on human biomechanical behavior., Methods: In this article, we performed a literature review on the biomechanical traits of human posture, and the proposed theories that explain the special characteristics present in idiopathic scoliosis., Results: The current theory on the etiopathogeneis of AIS suggests that dorsally directed shear loads acting on a preexisting axial plane rotation, in a posteriorly inclined sagittal plane of a growing patient, together with disc maturation, collagen quality at this phase of development and immaturity of proprioception, is the perfect scenario to spark rotational instability and create the three-dimensional deformity that defines idiopathic scoliosis., Conclusion: The unique spinal alignment of human bipedalism, gravity and muscle forces acting straight above the pelvis to preserve an upright balance, and the instability of the soft tissue in a period of growth development, is an appealing cocktail to try to explain the genesis of this condition in humans., (© 2023. The Author(s), under exclusive licence to Scoliosis Research Society.)

Study Design: This was a retrospective comparative study., Objective: To evaluate long-term outcomes of selective thoracic fusion (STF) using both rod derotation (RD) and direct vertebral rotation (DVR) with pedicle screw instrumentation (PSI) in the treatment of thoracic adolescent idiopathic scoliosis (AIS) with a minimum 10-year follow-up., Summary of Background Data: Postoperative compensation and maintenance of the unfused lumbar curve after STF is very important factor for the satisfactory results in the treatment of thoracic AIS., Patients and Methods: Sixty-five patients with thoracic AIS treated with STF from the neutral vertebra (NV) to NV or NV-1 with RD and DVR were retrospectively analyzed with a minimum 10-year follow-up. Patients were divided into 2 groups: satisfactory (n=52) and unsatisfactory groups (n=13). Unsatisfactory results were defined as an adding-on, a lowest instrumented vertebra (LIV) tilt of >10 degrees, or coronal balance >15 mm., Results: No significant differences were observed in the main thoracic curve between the satisfactory and unsatisfactory groups postoperatively (P=0.218) and at the last follow-up (P=0.636). Significant improvements of LIV tilt and disk angle were observed in both groups, but these improvements deteriorated during the follow-up period in the unsatisfactory group. Significant differences of apical vertebra (AV) and end vertebra (EV) were observed postoperatively (AV: P=0.001, EV: P=0.001) and at the last follow-up (AV: P<0.000, EV: P<0.000) between the 2 groups., Conclusions: STF using RD and DVR can achieve satisfactory deformity correction for thoracic AIS with satisfactory compensatory lumbar curve that was maintained over long-term follow-up. Progression of unfused lumbar curve closely related with LIV tilt and disk angle showing insufficient DVR. Therefore, STF with sufficient DVR required to achieve satisfactory deformity correction and prevent a distal adding-on phenomenon in the treatment of thoracic AIS.

Objective: We sought to compare the radiologic outcomes for different distal fusion levels in a rigid curve with major thoracolumbar and lumbar (TL/L) adolescent idiopathic scoliosis (AIS) using rod derotation (RD) with direct vertebral rotation (DVR) after pedicle screw instrumentation (PSI)., Methods: This study finally enrolled 28 patients who were diagnosed with AIS in rigid curve with major TL/L curves, treated by PSI with RD and DVR and with a minimum 2-year follow-up. Patients were divided into 2 groups, L3 and L4, on the basis of the distal fusion level at the lowest instrumented vertebra (LIV) of L3 or L4., Results: There was no significant difference in TL/L curve, thoracic (minor), and compensatory (caudal) curves between the L3 and L4 groups either postoperatively (P = 0.162, 0.426, and 0.762, respectively) or at the last follow-up (P = 0.952, 0.620, and 0.562, respectively). The overall prevalence of unsatisfactory results was 42.9% (12/28 patients). The prevalence of unsatisfactory results was 61.1% (11/18) in the L3 group and 10% (1/10) in the L4 group, which was significantly different (P < 0.05)., Conclusions: Unsatisfactory results occurred more often in the L3 group than in the L4 group, and unsatisfactory results had significant influence on progression of TL/L and distal compensatory curves. Such progression was closely correlated with deteriorating LIV disk angle in the L3 group. Therefore if the curve is rigid, LIV should be extended to L4 to avoid the adding-on phenomenon in the treatment of major TL/L AIS using RD with DVR after PSI., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: 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., Methods: 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)., Results: 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)., Conclusions: 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., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Rationale: The management of congenital scoliosis concentrates on early diagnosis and proper surgical treatment before the development of severe deformities. Decision making regarding the appropriate fusion levels, proper surgical treatment, and reduction amount of kyphoscoliosis is very important but difficult in the treatment of congenital scoliosis, especially in young children., Patient Concerns: We report an 11-year follow-up of revision surgery for fractional curve progression after combined anterior and posterior fusion without hemivertebra resection using pedicle screw fixation (PSF) in congenital kyphoscoliosis at age 4 years (a total 18-year follow-up). A T12 hemivertebra was documented in a 4-year-old girl and was treated by combined anterior and posterior fusion in two stages with PSF. The fusion mass was maintained but the distal compensatory curve progressed during the follow-up period. The patient underwent a posterior vertebral column resection (PVCR) with extended posterior fusion at the age of 11, 7 years after initial surgery., Outcomes: Eleven years after the revision surgery with PVCR, the patient showed satisfactory results and her spine was well balanced., Lessons: The cause of revision surgery for the curve progression may include inappropriate fusion level, incomplete hemivertebra resection, or failure of anterior and posterior fusion. Especially, inappropriate fusion level may result in deterioration of the compensatory curve even without progression of the fusion mass., Conclusion: Appropriate selection of fusion levels, complete resection of hemivertebra, and satisfactory reduction of scoliosis and kyphosis are important factors for deformity correction and prevention of progression of both main and compensatory curves (adding-on of structural curve or progression of compensatory curve) as well as reducing the influence of adjacent vertebral growth using as short a fusion as possible.

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.

Study Design: A retrospective study., Objective: To compare the surgical outcomes of posterior vertebral column resection (PVCR) and its long-term effects on the deformity correction for congenital scoliosis in children less than 18 years of age., Summary of Background Data: There have been no reports on surgical outcomes that pertain to the timing of surgery for congenital scoliosis in children under age 18 years with long term follow-up., Methods: Forty-five congenital scoliosis patients (N = 45) under age 18 at the time of surgery were treated by PVCR. These cases were retrospectively studied and had a minimum 10-year follow-up. We assigned patients into two groups: Group 1 (N = 19) patients who had surgery before 10 years of age, Group 2 (N = 26) patients who had surgery after 10 years of age., Results: In Group 1, the mean Cobb angle of the main curve was 44° before surgery, 10.2° after surgery, and 14.2° at last follow-up. In Group 2, the mean Cobb angle of the main curve was 48.7° before surgery, 17.2° after surgery, and 20.4° at the last follow-up. The mean operative time was 189 minutes in Group 1 and 245 minutes in Group 2. The mean estimated blood loss (EBL) per kilogram was 52.9 mL/kg in Group 1 and 48.1 mL/kg in Group 2. There were 22 complications for PVCR and the overall prevalence of complications was 48.9%., Conclusion: PVCR is an effective procedure for the management of congenital scoliosis under age 18. PVCR for congenital scoliosis before the age of 10 years had significantly better deformity correction compared with the group after the age of 10 years and did not cause crankshaft phenomenon., Level of Evidence: 4.

Rationale: Congenital scoliosis due to a hemivertebra creates a wedge-shaped deformity, which progresses and causes severe spinal deformities as an individual grows. The treatment of congenital scoliosis focuses on early diagnosis and appropriate surgical management before the development of severe deformity., Patient Concerns: We report the case of a 4-year-old male child with a left thoracolumbar scoliosis of 27° (T10-T12) due to a T11 hemivertebra who was treated by posterior fusion and pedicle screw fixation at the age of 4 years. The implant was removed due to pain secondary to implant prominence after 4 years without definitive revision surgery, which led to significant progression of the scoliosis, to 50°. The indication for posterior vertebral column resection (PVCR) is a congenital spinal deformity with a curve magnitude greater than 30° with fast progression. This includes documented progression of the curve by more than 5° in a 6- month period, failure of conservative treatment, or both., Outcomes: The patient underwent PVCR of the T11 hemivertebra. Nine years after the revision surgery with PVCR, the patient showed satisfactory results and his spine was well balanced., Lessons: This case shows that removal of an implant that was not the only cause of curve progression at a young age may lead to progression of scoliosis and, therefore, should be avoided unless it is absolutely necessary., Conclusion: Congenital scoliosis due to a hemivertebra at a young age could be treated by hemivertebra resection or anterior and posterior epiphysiodesis as definitive surgical treatment. The patient was eventually treated with PVCR, which achieved satisfactory correction without curve progression in a long-term follow-up., Competing Interests: The authors have no conflicts of interest to disclose.

OBJECTIVE There have been no reports on the long-term radiographic outcomes of posterior vertebral column resection (PVCR) in patients with congenital scoliosis. The purpose of this study was to evaluate the surgical outcomes and complications after PVCR and its long-term effects on correcting this deformity in children with congenital scoliosis. METHODS The authors retrospectively analyzed the medical records of 45 patients with congenital scoliosis who were younger than 18 years at the time of surgery and who underwent PVCR and fusion with pedicle screw fixation (PSF). The mean age of the patients at the time of surgery was 11.3 years (range 2.4-18.0 years), and the mean length of follow-up was 12.8 years (range 10.1-18.2 years). RESULTS The mean Cobb angle of the main curve was 46.5° before PVCR, 13.7° immediately after PVCR, and 17.6° at the last follow-up. For the compensatory cranial curve, PVCR corrected the preoperative Cobb angle of 21.2° to 9.1° postoperatively and maintained it at 10.9° at the last follow-up. For the compensatory caudal curve, the preoperative Cobb angle of 23.8° improved to 7.7° postoperatively and was 9.8° at the last follow-up. The authors noted 22 complications, and the overall incidence of complications was 48.9%. CONCLUSIONS Posterior vertebral column resection is an effective procedure for managing congenital scoliosis in patients younger than 18 years. Use of PVCR and fusion with PSF for congenital scoliosis achieved rigid fixation and satisfactory deformity correction that was maintained over the long term. However, the authors note that PVCR is a technically demanding procedure and entails risks for major complications and excessive blood loss.

The etiology of congenital scoliosis and its development remains unclear and has not yet been fully identified, even there are theories that congenital scoliosis could be derived from the failure of formation or failure of segmentation, which are etiologically heterogeneous with genetic, epigenetic, and environmental factors contributing to their occurrence. We reported a case of long-term follow-up after posterior vertebral column resection (PVCR) in both identical twins with similar congenital kyphoscoliosis at thoracolumbar levels. Twin I had been noticed by his parents to have asymmetry of his back at age 5 years, but no treatment was given. Twin II was first noticed to have a spinal problem at 11 years of age by his parents. Overtime, spine of both twins became further deviated to the left with kyphosis and was referred to our hospital. Both monozygotic twins were treated by PVCR and satisfactory results were demonstrated at 10-year follow-up.This case is the first report on the surgical treatment with PVCR, almost simultaneously, in both identical twins who had similar congenital vertebral anomalies causing kyphoscoliosis. Both identical twins with congenital kyphoscoliosis had undergone surgical correction by PVCR, anterior support with a mesh cage and posterior fusion using pedicle screws at the age of 14 years and achieved a satisfactory correction and a stable spine without curve progression with 10-year follow-up., Competing Interests: The authors have no funding and conflicts of interest to disclose. Institutional Review Board approval of Inje University Sanggye Paik Hospital (IRB No. 2015-02-019) was obtained before data collection and analysis.

Background Context: There is little information regarding the surgical outcomes with regard to the timing of surgery in children under age 10 years for congenital scoliosis with a long-term follow-up., Purpose: The purpose of this study was to compare the surgical outcomes for congenital scoliosis in children 6 years or older but less than 10 years of age., Study Design: This is a retrospective study., Patient Sample: Eighteen congenital scoliosis patients under age 10 years at the time of surgery were treated by posterior hemivertebra resection and bilateral pedicle screw fixation., Outcome Measures: Outcome measures are radiological outcomes (plain radiographs and computed tomography) and complications., Methods: Eighteen congenital scoliosis patients (n=18) under age 10 years at the time of surgery were treated by posterior hemivertebra resection and bilateral pedicle screw fixation. These cases were retrospectively studied and had a minimum of 7-year follow-up. We assigned patients into two groups: Group 1 (n=9) patients who had surgery before 6 years of age and Group 2 (n=9) those who had surgery after 6 years of age., Results: The groups were not found to be statistically different in operative time, blood loss, and follow-up period. In the Group 1, the mean Cobb angle of the main curve was 32.4° before surgery, 6.4° after surgery, and 9.1° at last follow-up. In the Group 2, the mean Cobb angle of the main curve was 36.5° before surgery, 10.4° after surgery, and 14.5° at last follow-up. There was significantly better deformity correction of main curve immediate postoperatively and at last follow-up in Group 1. No significant difference was observed in growth rate of the vertebral body and spinal canal parameters comparing the two groups at the vertebra with or without screws. There was no crankshaft phenomena, no clinical or radiographic features suggestive of spinal stenosis during follow-up, and no major vascular or neurological complications related to the pedicle screws in either group., Conclusions: In congenital scoliosis patients, posterior hemivertebra resection after pedicle screw fixation before the age of 6 years had significantly better deformity correction and did not cause a negative effect on the growth of vertebral body or spinal canal compared with the group treated after 6 years of age. Therefore, early surgical correction of a congenital hemivertebra in children under 6 years of age, before structural changes occur, effectively achieves a more satisfactory correction without causing iatrogenic spinal stenosis or neurologic complications compared with children older than 6 years but under 10 years of age., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Study Design: A retrospective study., Objective: To evaluate the surgical outcomes of posterior hemivertebra resection and short segment fusion with segmental pedicle screw fixation in congenital scoliosis in children younger than 10 years., Summary of Background Data: This is the first long-term follow-up on surgical outcomes of posterior hemivertebra resection and short segment fusion using segmental pedicle screw fixation in children younger than 10 years with congenital scoliosis., Methods: Patients with congenital scoliosis (n = 18) younger than 10 years at the time of the surgery were treated by posterior hemivertebra resection and bilateral pedicle screw fixation. The mean age at the time of surgery was 6.6 years (range, 2.6-9.8 yr). They were retrospectively studied with a mean follow-up of 11.4 years (range, 7.1-17.3 yr)., Results: The mean Cobb angle of the main curve was 34.4° before surgery, 8.6° after surgery, and 12.9° at last follow-up. In the compensatory cranial curve, the preoperative Cobb angle of 14.5° was corrected to 5.9° postoperatively and was 8.4° at last follow-up. In the compensatory caudal curve, the preoperative Cobb angle of 17.4° improved to 4° postoperatively and 6.6° at last follow-up. There were no crankshaft phenomena and no clinical and radiographical features suggestive of spinal stenosis during follow-up. There were no major vascular or neurological complications related to the pedicle screws., Conclusion: Posterior hemivertebra resection after pedicle screw fixation in congenital scoliosis is a safe and effective procedure that can achieve rigid fixation and deformity correction and restore spinal balance. This study showed that early posterior hemivertebra resection of congenital scoliosis before structural changes occur above or below can reduce fusion length, prevent curve progression, and effectively achieve a more satisfactory correction without hazardous iatrogenic spinal stenosis, crankshaft phenomena, or neurological complications., Level of Evidence: 3.

Study Design: A retrospective comparative study., Objective: To evaluate the shoulder balance resulting from the correction of double thoracic adolescent idiopathic scoliosis (AIS) comparing rod derotation (RD) with direct vertebral rotation (DVR) and RD only after pedicle screw instrumentations., Summary of Background Data: This is the first report on the effect of DVR on the shoulder balance using segmental pedicle screw instrumentation in the treatment of double thoracic AIS with minimum 5-year follow-up., Methods: Patients with double thoracic AIS (n = 57) were treated by fusing both thoracic curves with RD and DVR (n=35), or RD (n=22) methods and retrospectively studied with a minimum 5 years of follow-up., Results: In the RD with DVR group, the preoperative proximal thoracic curve of 40.2° improved to 17.9° postoperatively and 19.9° at the last follow-up. In the RD group, the preoperative proximal thoracic curve of 37.5° improved to 22.4° postoperatively and 23.2° at the last follow-up. In the RD with DVR group, the preoperative distal thoracic curve of 56.6° improved to 16.1° postoperatively and 16.7° at the last follow-up. In the RD group, the preoperative distal thoracic curve of 50.6° improved to 17.8° postoperatively and 18.2° at the last follow-up. In the RD with DVR group, the average preoperative shoulder height difference of 16.3 mm had improved to 7.2 mm postoperatively and was 7.0 mm at the last follow-up. In the RD group, the average preoperative shoulder height difference of 15.1 mm had changed to 7.5 mm postoperatively and was 7.3 mm at the last follow-up., Conclusion: Shoulder balance had not significantly improved even with additional correction method of DVR using segmental pedicle screw instrumentation in double thoracic AIS. The proximal thoracic curve was rigid and corrected less in both groups. Therefore, less correction of the distal thoracic curve effectively achieves better shoulder balance., Level of Evidence: 3.

Introduction: There is controversy regarding the appropriate proximal fusion level for adult degenerative scoliosis. Ideally, the horizontal vertebra is chosen for the upper instrumented vertebra to create a balanced spine. Fusion to T10 is recommended to prevent junctional problems at the proximal adjacent segment. The purpose of this retrospective study was to determine the optimal proximal fusion level for adult degenerative lumbar scoliosis., Materials and Methods: Fifty-one patients with adult degenerative lumbar scoliosis (mean age 64.6 years) who underwent posterior instrumentation were analyzed after a minimum 2-year follow-up. The average number of levels fused was 5.9 segments (range 3-9) with distal fusion at L5 in 30 patients and S1 in 21 patients. The upper instrumented vertebra (UIV) ranged from T9 to L2. According to the relationship between UIV, horizontal vertebra (HV) and upper end vertebra (UEV), the patients were divided into three groups in the coronal plane: Group HV (UIV = HV or above); Group HV-UEV (UIV = between HV and UEV); and Group UEV (UIV = UEV or below). In the sagittal plane; the patients were divided into Group T9-10 (UIV = T9-10), Group T11-12 and Group L1-2., Results: Proximal adjacent segment disease (ASD) was identified in 13 (25 %) out of 51 patients, including junctional kyphosis (n = 5), compression fractures (n = 4), progression of disc wedging (n = 2) and spinal stenosis (n = 2). Group UEV had more ASD (9 of 16 patients) compared to Group HV (2 of 21 patients) and Group HV-UEV (2 of 14 patients). It appeared that neutral vertebra could be a criterion for the selection of UIV in the coronal plane. Among the groups divided in the sagittal plane, proximal ASD was found in 47 % of 19 patients in Group L1-2, which was notably higher than 9 % in Group T9-10 and 20 % in Group T11-12., Conclusions: Proximal adjacent segment disease developed more commonly when the proximal fusion stopped at the UEV or below in adult degenerative lumbar scoliosis. UIV must be above UEV in the coronal plane. Fusion to T11 or T12 was acceptable when UIV was above UEV, since there was no significant difference in the rate of proximal adjacent segment between fusion to T10 and fusion to T11 or T12.

Introduction: Pedicle screw instrumentation in AIS has advantages of rigid fixation, improved deformity correction and a shorter fusion, but needs an exacting technique., Materials and Methods: The author has been using the K-wire method with intraoperative single PA and lateral radiographs, because it is safe, accurate and fast. Pedicle screws are inserted in every segment on the correction side (thoracic concave) and every 2-3 on the supportive side (thoracic convex). After an over-bent rod is inserted on the corrective side, the rod is rotated 90° counterclockwise. This maneuver corrects the coronal and sagittal curves. Then the vertebra is derotated by direct vertebral rotation (DVR) correcting the rotational deformity. The direction of DVR should be opposite to that of the vertebral rotation. A rigid rod has to be used to prevent the rod from straightening out during the rod derotation and DVR. The ideal classification of AIS should address all curve patterns, predicts accurate fusion extent and have good inter/intraobserver reliability. The Suk classification matches the ideal classification is simple and memorable, and has only four structural curve patterns; single thoracic, double thoracic, double major and thoracolumbar/lumbar. Each curve has two types, A and B. When using pedicle screws in thoracic AIS, curves are usually fused from upper neutral to lower neutral vertebra. Identification of the end vertebra and the neutral vertebra is important in deciding the fusion levels and the direction of DVR. In lumbar AIS, fusion is performed from upper neutral vertebra to L3 or L4 depending on its curve types., Conclusions: Rod derotation and DVR using pedicle screw instrumentation give true three dimensional deformity correction in the treatment of AIS. Suk classification with these methods predicts exact fusion extent and is easy to understand and remember.

The pedicle is a power nucleus of the vertebra and offers a secure grip of all 3 columns. Pedicle screw instrumentation has advantages of rigid fixation with improved three-dimensional (3D) correction and it is accepted as a reliable method with a high margin of safety. Accurate placement of the pedicle screws is important to reduce possible irreversible complications. Many methods of screw insertion have been reported. The author has been using the K-wire method coupled with the intraoperative single posteroanterior and lateral radiographs, which is the most safe, accurate and fast method. Identification of the curve patterns and determining the fusion levels are very important. The ideal classification of adolescent idiopathic scoliosis should address the all patterns, predict the extent of accurate fusion and have good inter/intraobserver reliability. My classification system matches with the ideal classification system, and it is simple and easy to learn; and my classification system has only 4 structural curve patterns and each curve has 2 types. Scoliosis is a 3D deformity; the coronal and sagittal curves can be corrected with rod rotation, and rotational deformity has to be corrected with direct vertebral rotation (DVR). Rod derotation and DVR are true methods of 3D deformity correction with shorter fusion and improved correction of both the fused and unfused curves, and this is accomplished using pedicle screw fixation. The direction of DVR is very important and it should be opposite to the direction of the rotational deformity of the vertebra. A rigid rod has to be used to prevent rod bend-out during the derotation and DVR.

Study Design: A retrospective study of clinical results of operative treatment for degenerative lumbar scoliosis., Objective: To determine the risk factors of sagittal decompensation after long instrumentation and fusion to L5 or S1., Summary of Background Data: Little is known about the risk factors for sagittal decompensation, which was defined in this study as sagittal C7 plumb falling anterior >8 cm from the posterosuperior corner of the sacrum., Methods: Forty-five patients (mean age: 64.4 year) with adult degenerative lumbar scoliosis were reviewed retrospectively with a minimum 2 years. The mean number of levels fused was 6.1 +/- 1.6 segments. The upper instrumented vertebra ranged from T9 to L2. The lower instrumented vertebra was L5 and S1 in 24 and 21 patients, respectively., Results: Sagittal decompensation (SD) developed in 19 patients. The most significant risk factors of SD were preoperative sagittal imbalance and high pelvic incidence. The preoperative sagittal C7 plumb was more positive (67.9 mm) in the decompensation group than in the balance group (37.0 mm) (P = 0.002). There was a significant difference in pelvic incidence between 61.7 degrees in the decompensation and 54.9 degrees in the balance group (P = 0.01). The preoperative lumbar lordosis was hypolordotic in the decompensation group, however, it was not found to be a risk factor. Pseudarthrosis was identified at the lumbosacral junction in 5 patients, and 4 of them (80%) had SD. SD developed in 55% of patients who had loosening of the distal screws and 50% of patients with hypolordotic lumbar fusion. Distal adjacent segment disease was more likely to cause SD than proximal adjacent segment disease., Conclusion: Sagittal decompensation is common after long posterior instrumentation and fusion for degenerative lumbar scoliosis. It is mostly associated with complications at the distal segments, including pseudarthrosis and implant failure at the lumbosacral junction. Restoration of optimal lumbar lordosis and secure lumbosacral fixation is necessary especially in patients with preoperative sagittal imbalance and high pelvic incidence in order to prevent sagittal decompensation after surgery.

There is a debate regarding the distal fusion level for degenerative lumbar scoliosis. Whether a healthy L5-S1 motion segment should be included or not in the fusion remains controversial. The purpose of this study was to determine the optimal indication for the fusion to the sacrum, and to compare the results of distal fusion to L5 versus the sacrum in the long instrumented fusion for degenerative lumbar scoliosis. A total of 45 patients who had undergone long instrumentation and fusion for degenerative lumbar scoliosis were evaluated with a minimum 2 year follow-up. Twenty-four patients (mean age 63.6) underwent fusion to L5 and 21 patients (mean age 65.6) underwent fusion to the sacrum. Supplemental interbody fusion was performed in 12 patients in the L5 group and eleven patients in the sacrum group. The number of levels fused was 6.08 segments (range 4-8) in the L5 group and 6.09 (range 4-9) in the sacrum group. Intraoperative blood loss (2,754 ml versus 2,938 ml) and operative time (220 min versus 229 min) were similar in both groups. The Cobb angle changed from 24.7 degrees before surgery to 6.8 degrees after surgery in the L5 group, and from 22.8 degrees to 7.7 degrees in the sacrum group without statistical difference. Correction of lumbar lordosis was statistically better in the sacrum group (P = 0.03). Less correction of lumbar lordosis in the L5 group seemed to be associated with subsequent advanced L5-S1 disc degeneration. The change of coronal and sagittal imbalance was not different in both groups. Subsequent advanced L5-S1 disc degeneration occurred in 58% of the patients in the L5 group. Symptomatic adjacent segment disease at L5-S1 developed in five patients. Interestingly, the development of adjacent segment disease was not related to the preoperative grade of disc degeneration, which proved minimal degeneration in the five patients. In the L5 group, there were nine patients of complications at L5-S1 segment, including adjacent segment disease at L5-S1 and loosening of L5 screws. Seven of the nine patients showed preoperative sagittal imbalance and/or lumbar hypolordosis, which might be risk factors of complications at L5-S1. For the patients with sagittal imbalance and lumbar hypolordosis, L5-S1 should be included in the fusion even if L5-S1 disc was minimal degeneration.

Study Design: Retrospective study., Objective: To evaluate the effect and outcome of thoracoplasty in conjunction with pedicle screw instrumentation in the treatment of thoracic adolescent idiopathic scoliosis (AIS)., Summary of Background Data: Some spine surgeons recently think more correction of hump deformity using pedicle screws without thoracoplasty. Although thoracoplasty has been conventional treatment of rib hump, there are few papers about the results of pedicle screw instrumentation and concomitant thoracoplasty., Methods: Eighty-seven patients with thoracic AIS (mean age, 14.4 years) treated by pedicle screw instrumentation were retrospectively analyzed after a minimum follow-up of 2 years. Patients were divided into 3 groups; N-T group (no thoracoplasty with iliac bone graft, n = 37), T+N-DVR [thoracoplasty without direct vertebral rotation (DVR), n = 20] and T+DVR group (thoracoplasty with DVR, n = 30). In the T (T+N-DVR and T+DVR) group, 4 to 8 ribs were resected and used for bone graft. Patients were evaluated for deformity correction, balance, pulmonary function, height and angle of rib hump, clinical outcomes (SRS-30), and complications., Results: In the N-T group, the thoracic curve was corrected from 53 degrees to 16 degrees (69% correction), in the T+N-DVR group from 55 degrees to 18 degrees (69%) and in the T+DVR group from 54 degrees to 10 degrees (81%). There was no difference in postoperative spinal balance and pulmonary function among the 3 groups. The correction rates of hump height and angle were 35% and 38% in the N-T group, respectively, 57% and 58% in the T+N-DVR, and 70% and 72% in the T+DVR. The T group showed significantly better correction of rib hump and self-image score in the SRS-30 questionnaire than the N-T group. There were 8 iliac donor site problems in the N-T group and 3 hemothorax in the T group, which had no adverse effect in the final result., Conclusion: Thoracoplasty showed significantly better rib hump correction, satisfactory clinical outcomes without pulmonary function compromise, or iliac bone graft site morbidity in the treatment of thoracic AIS with pedicle screw instrumentation.

The extent of fusion for degenerative lumbar scoliosis has not yet been determined. The purpose of this study was to compare the results of short fusion versus long fusion for degenerative lumbar scoliosis. Fifty patients (mean age 65.5 +/- 5.1 years) undergoing decompression and fusion with pedicle screw instrumentation were evaluated. Short fusion was defined as fusion within the deformity, not exceeding the end vertebra. Long fusion was defined as fusion extended above the upper end vertebra. The lower end vertebra was included in the fusion in all the patients. The short fusion group included 28 patients and the long fusion group included 22 patients. Patients' age and number of medical co-morbidities were similar in both the groups. The number of levels fused was 3.1 +/- 0.9 segments in the short fusion group and 6.5 +/- 1.5 in the long fusion group. Before surgery, the average Cobb angle was 16.3 degrees (range 11-28 degrees ) in the short fusion group and 21.7 degrees (range 12-33 degrees ) in the long fusion group. The correction of the Cobb angle averaged 39% in the short fusion group and 72% in the long fusion group with a statistical difference (P = 0.001). Coronal imbalance improved significantly in the long fusion group more than in the short fusion group (P = 0.03). The correction of lateral listhesis was better in the long fusion group (P = 0.02). However, there was no difference in the correction of lumbar lordosis and sagittal imbalance between the two groups. Ten of the 50 patients had additional posterolateral lumbar interbody fusion at L4-5 or L5-S1. The interbody fusion had a positive influence in improving lumbar lordosis, but was ineffective at restoring sagittal imbalance. Early perioperative complications were likely to develop in the long fusion group. Late complications included adjacent segment disease, loosening of screws, and pseudarthrosis. Adjacent segment disease developed in ten patients in the short fusion group, and in five patients in the long fusion group. In the short fusion group, adjacent segment disease occurred proximally in all of the ten patients. Loosening of distal screws developed in three patients, and pseudarthrosis at L5-S1 in one patient in the long fusion group. Reoperation was performed in four patients in the long fusion group and three patients in the short fusion group. In conclusion, short fusion is sufficient for patients with small Cobb angle and good spinal balance. For patients with severe Cobb angle and rotatory subluxation, long fusion should be carried out to minimize adjacent segment disease. For patients who have severe sagittal imbalance, spinal osteotomy is an alternative technique to be considered. As long fusion is likely to increase early perioperative complications, great care should be taken for high-risk patients to avoid complications.

Study Design: Radiographic analysis was performed retrospectively. Outcomes and complications were collected prospectively., Objectives: To assess complications after posterior fusion and instrumentation for degenerative lumbar scoliosis, to determine risk factors of complications, and to analyze the clinical outcomes of surgery., Summary of Background Data: The complications after degenerative lumbar scoliosis surgery have reported to be high. Risk factors for developing complications are unknown., Methods: Forty-seven patients (average age, 66.6 years; range, 48-83 years) with degenerative lumbar scoliosis undergoing posterior fusion and instrumentation were analyzed. Seven patients had additional posterior lumbar interbody fusion at the lumbosacral junction. The average number of levels fused was 4.7 +/- 2.2 segments. We evaluated the early perioperative (<3 months after surgery) and late complications., Results: There were 14 early perioperative complications and 18 late complications. There was 1 case of mortality by pulmonary embolism. Early complications included ileus, urinary tract infection, transient delirium, superficial infection, and neurologic deficit. Late complications included adjacent segment diseases, pseudarthrosis, and loosening of screws. Adjacent segment disease developed at the proximal segment in 10 patients and at the distal segment in 5 patients. Pseudarthrosis was noted at the lumbosacral junction in 2 patients. Revision surgery was performed in 7 patients. Older patients (>65 years) had the tendency to increase early complications without statistical difference (P = 0.053). Excessive intraoperative blood loss was the most significant risk factor for the development of early perioperative complications, and number of levels fused was related to blood loss. Operative time and multiple medical comorbidities were not associated with higher complication rate. There were no specific factors related to the development of late complications., Conclusion: The complication rate after posterior fusion and instrumentation for degenerative lumbar scoliosis was 68%. Abundant blood loss was a significant risk factor for early perioperative complications. The improvement of Oswestry disability index was less in patients with late complications.

With the advent of segmental pedicle screw fixation that enables more powerful corrective forces, it is postulated that an additional anterior procedure may be unnecessary even in severe deformities. The purpose of this paper is to evaluate the results of a posterior procedure alone using segmental pedicle screw fixation in severe scoliotic curves over 70 degrees . Thirty-five scoliosis patients treated by pedicle screw fixation and rod derotation were retrospectively analyzed after a minimum follow-up of 2 years (range 2-10.4). The mean age of patients was 15.3 years (range 9.8-34.2). Diagnoses were idiopathic scoliosis in 29, neuromuscular scoliosis in 3 and scoliosis associated with Marfan syndrome in 3. Scoliosis consisted of single thoracic curve in 18, double thoracic in 5 and double major in 12. Twenty-five patients showed a major thoracic curve greater than 70 degrees (range 70-100), and different ten patients showed a major lumbar curve greater than 70 degrees (range 70-105), pre-operatively. The deformity angle, lowest instrumented vertebral tilt (LIVT) and spinal balance were measured. Pre-operatively there were nine patients with coronal decompensation. The pre-operative thoracic curve of 80 +/- 9 degrees with the flexibility of 45 +/- 11% (45 +/- 11 degrees in side-bending film) was corrected to 27 +/- 10 degrees at the most recent follow-up, showing a correction of 66% (53 degrees) and loss of correction of 3.0% (3.7 degrees). The pre-operative lumbar curve of 79 +/- 12 degrees with the flexibility of 62 +/- 14% (30 +/- 11 degrees in side-bending film) was corrected to 33 +/- 14 degrees at the most recent follow-up [59% (46 degrees) curve correction, 3.5% (3.0 degrees) loss of curve correction]. The pre-operative LIVT of 30 +/- 8 degrees was corrected to 11 +/- 6 degrees, showing a correction of 62% (19 degrees). Residual coronal decompensation was observed in three patients postoperatively. Pre-operative thoracic kyphosis of 27 degrees (range 0-82) improved postoperatively to 31 degrees (range 14-53). In conclusion, posterior segmental pedicle screw fixation without anterior release in severe scoliosis had satisfactory deformity correction without significant loss of curve correction. In this series a posterior procedure alone obviated the need for the anterior release and avoided complications related anterior surgery.

Study Design: Retrospective study., Objectives: To evaluate outcomes of selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis with a minimum 5-year follow-up., Summary of Background Data: Segmental pedicle screw fixation has been proven to enable true segmental control and greater correction both in coronal and sagittal planes of scoliosis. However, there is no long-term study of selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis., Methods: Two hundred and three thoracic idiopathic scoliosis patients with 236 thoracic curves subject to selective thoracic fusion with segmental pedicle screw fixation were analyzed. Mean patient age at the time of operation was 13.8 years (range: 8.9-18)., Results: The preoperative thoracic curve of 51 +/- 12 degrees was corrected to 16 +/- 7 degrees (69% correction, 3% loss of correction) at the most recent follow-up. The noninstrumented lumbar curve of 30 +/- 10 degrees was corrected to 10 +/- 8 degrees (66% correction, 5% loss of correction) at the most recent follow-up. The preoperative thoracic kyphosis of 18 +/- 11 degrees and the lumbar lordosis of 43 +/- 10 degrees were improved to 23 +/- 8 degrees and 46 +/- 9 degrees , respectively, at the most recent follow-up. There was no junctional kyphosis at the most recent follow-up. Coronal decompensation at the most recent follow-up occurred in 10 patients. Postoperative adding-on occurred in 17 patients, who were fused two levels short of the neutral vertebra. Of the 2,867 thoracic pedicle screws inserted in the thoracic level, 43 screws were found to be malpositioned (1.5%), but they did not cause neurologic complications or adversely affect the long-term results., Conclusions: Selective thoracic fusion with segmental pedicle screw fixation in thoracic idiopathic scoliosis had satisfactory radiographic and clinical outcomes after surgery and has been well-maintained for minimum 5-year follow-up. It is a safe and effective method for preservation of lumbar motion segments as well as for restoration and maintenance of both coronal and sagittal alignment.

Study Design: Retrospective study., Objective: To report on the technique and results of posterior vertebral column resection (PVCR) for severe rigid scoliosis., Summary of Background Data: The treatment of severe rigid scoliosis is a demanding surgical challenge. Conventional procedures such as combined anteroposterior instrumentation enable limited correction. In rigid scoliosis, vertebral column resection is a better option for accomplishing translation of spinal column. PVCR is performed through a single posterior approach., Methods: A total of 16 patients with scoliosis (average age 29 years) subjected to PVCR were retrospectively reviewed after a minimum follow-up of 2 years (range 2-6.8). The indication for PVCR was scoliosis more than 80 degrees , with flexibility less than 25%. The radiographic parameters were evaluated, and clinical records were reviewed., Results: The number of vertebrae removed averaged 1.3, and 21 total (15 thoracic and 6 lumbar). Average fusion extent was 10.6 vertebrae. The mean preoperative scoliosis of 109.0 degrees was corrected to 45.6 degrees (59% correction) at the most recent follow-up, and the minor curve of 59.3 degrees was corrected to 29.2 degrees (51% correction). The mean preoperative coronal imbalance of 4.0 cm was improved to 1.0 cm at the most recent follow-up, and sagittal imbalance of 4.2 cm was improved to 1.6 cm. Complications were encountered in 4 patients, including 1 complete paralysis, 1 hematoma, 1 hemopneumothorax, and 1 proximal junctional kyphosis., Conclusions: PVCR is an effective alternative for severe rigid scoliosis. It is a highly technical procedure and should only be performed by an experienced surgical team.

Study Design: Scoliosis patients were prospectively x-rayed in three positions with independent analysis., Objectives: To determine if one positioning technique provides superior visualization of critical landmarks (C7, T2, T12, L5-S1) and to determine any position dependent variations in regional measures or sagittal balance., Summary of Background Data: Different techniques for positioning patient's arms are used for 36" lateral radiograph with no data on relative effects., Methods: A total of 25 scoliosis patients were prospectively studied with 36" lateral radiographs in three positions varying arm location (straight out, partially flexed, and the "clavicle" position). Films were analyzed independently by three surgeons. Vertebral landmarks were scored for clarity; and lordosis, kyphosis, and global balance were analyzed. Statistical analysis was done with a General Estimating Equations model., Results: The overall visualization score for the clavicle position was superior to either the 60 degrees or 90 degrees positions (clavicle vs. 60 degrees, P < 0.0001; clavicle vs. 90 degrees, P < 0.0003). Analysis of vertebral landmarks showed significantly better visualization of T2 with clavicle versus 90 degrees (P < 0.047), better visualization of T12 with clavicle versus either 60 degrees (P < 0.006) or 90 degrees (P < 0.049), and better visualization of L5-S1 with clavicle versus 90 degrees (P < 0.02). Regional measures showed no differences, but sagittal balance was significantly more positive in the 60 degrees position than either clavicle (P < 0.04) or 90 degrees (P < 0.015)., Conclusions: The clavicle position for obtaining lateral 36" radiographs produces significantly better overall visualization of critical vertebral landmarks. Regional measures do not differ between the three positions, but global balance is more positive with the 60 degrees position. Clinically, the clavicle position may result in more accurate radiographic measures and may minimize repeated radiograph exposures.

Study Design: A prospective study., Objectives: To introduce a new technique, direct vertebral rotation, and to compare the surgical results of direct vertebral rotation with those of simple rod derotation., Summary of Background Data: Pedicle screw fixation with a simple rod derotation maneuver enables a powerful coronal and sagittal plane correction in scoliosis surgery. However, the ability of achieving rotational correction is still unclear., Methods: Thirty-eight adolescent idiopathic scoliosis patients treated with segmental pedicle screw fixation were analyzed. The first group (n = 17) was treated by direct vertebral rotation; the second group (n = 21) was treated by simple rod derotation. All patients had a minimum follow-up of 2 years. Having similar preoperative curve patterns, both groups were evaluated for the deformity correction, lower instrumented vertebral tilt, and spinal balance. Apical vertebral rotation was evaluated by computed tomography scans. Surgical techniques of direct vertebral rotation were as follows: a precontoured rod was inserted into segmental screws on the concave side in thoracic scoliosis; a simple rod derotation was performed; and then the screws on the juxta-apical vertebrae, both on concave and convex sides, were rotated opposite direction to the rod derotation. Then, all the screws were sequentially tightened., Results: In the direct vertebral rotation group, the average preoperative apical vertebral rotation of 16.7 degrees was corrected to 9.6 degrees, showing 42.5% correction, whereas in the simple rod derotation group, the correction was negligible from 16.1 degrees to 15.7 degrees (2.4%). In the direct vertebral rotation group, the average preoperative thoracic curve of 55 degrees was corrected to 12 degrees (79.6%), and the lumbar curve of 39 degrees was corrected to 7 degrees (80.5%). In the simple rod derotation group, the preoperative thoracic curve of 53 degrees was corrected to 17 degrees (68.9%), and the lumbar curve of 39 degrees was corrected to 16 degrees (62.2%). The average lower instrumented vertebral tilt correction was 80.6% and 66.3% in the directvertebral rotation and the simple rod derotation group, respectively. There were statistically significant differences in the coronal curve, lower instrumented vertebral tilt, and rotational correction (P < 0.05, Mann-Whitney U test). Thoracic kyphosis was improved in both groups., Conclusions: Segmental pedicle screw fixation with "direct vertebral rotation" showed better rotational and coronal correction than "simple rod derotation."

Study Design: A retrospective study was conducted., Objective: To determine the exact distal fusion level in the treatment of single thoracic idiopathic scoliosis (King Types 3 and 4) with segmental pedicle screw fixation., Summary of Background Data: Pedicle screw fixation effectively shortens the distal fusion extent by improved three-dimensional deformity correction. However, the selection of distal fusion extent remains controversial in single thoracic idiopathic scoliosis., Methods: This study analyzed 42 patients with single thoracic adolescent idiopathic scoliosis (32 King 3 patients and 10 King 4 patients) who underwent segmental pedicle screw fixation and had a minimum follow-up period of 2 years (range, 2-6 years). The patients were grouped according to the distal fusion level with reference to the standing neutral rotated vertebra (NV) for comparison of deformity correction and spinal balance using standing radiographs. Failure to restore an adequate trunk balance and progression or extension of the primary curve (adding on) was considered unsatisfactory., Results: Preoperative 50 degrees +/- 11 degrees of thoracic deformity was corrected to 13 degrees +/- 5 degrees, for a curve correction of 74%. Preoperative 23 degrees +/- 7 degrees of lumbar deformity was corrected to 2 degrees +/- 8 degrees, for a curve correction of 93%. Curve correction was not significantly affected by King type or distal fusion level (P > 0.05). Postoperative unsatisfactory results were obtained in 14 patients. When the preoperative NV was the same or one level distal to end vertebra (EV), fusion down to NV was satisfactory (14/14). When the preoperative NV was more than two levels distal to EV, fusion down to one level shorter than NV (NV-1) also was satisfactory (9/9). However, when fusion down to NV-2 or shorter was performed, the chances of adding on were higher (14/19; P < 0.01). Preoperative 17 degrees +/- 8 degrees of thoracic kyphosis was improved to 24 degrees +/- 7 degrees., Conclusions: In single thoracic idiopathic scoliosis, NV is an important factor for the determination of fusion level. When preoperative NV and EV show no more than two-level gap differences, the curve should be fused down to NV. When the gap is more than two levels, fusion down to NV-1 is satisfactory, saving one or two motion segments, as compared with fusion extending to the stable vertebra.

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]