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Study Design: Retrospective. Purpose: To evaluate the relationship between shoulder/ neck imbalance with distal adding-on phenomenon and to identify other risk factors in Lenke 1 and 2 (non-AR curves) adolescent idiopathic scoliosis (AIS) patients. Methods: 100 Lenke 1 and 2 AIS patients with lowest instrumented vertebra (LIV) cephalad to or at L1 were recruited. Medial shoulder/ neck balance was represented by T1-tilt and cervical axis (CA). Lateral shoulder balance was represented by clavicle angle (Cla-A) and radiographic shoulder height (RSH). Distal adding-on phenomenon was diagnosed when there was disc wedging below LIV of >5o at final follow-up. Predictive factors and odds ratio were derived using univariate and multivariate logistic regression analysis. Results: Mean age of this cohort was 15.9 ± 4.4 years. Mean follow-up duration was 30.9 ± 9.6 months. Distal adding-on phenomenon occurred in 19 patients (19.0%). Only Risser grade, preoperative CA and final follow-up lumbar Cobb angle were the independent factors. A positive preoperative CA deviation increased the odds of distal adding-on by 5.4 times (95% CI 1.34-21.51, P = 0.018). The mean immediate postoperative T1-tilt, CA, RSH and Cla-A were comparable between the group with distal adding-on and the group without. Conclusion: Distal adding-on phenomenon occurred in 19.0% of patients. Preoperative "Cervical Axis" was an important factor and it increased the risk of distal adding-on by 5.4 times. Other significant predictive factors were Risser grade and lumbar Cobb angle at final follow-up. Immediate postoperative shoulder or neck imbalance was not a significant factor for postoperative distal adding-on phenomenon. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective propensity score matching (PSM) study. Objective: To investigate the perioperative outcomes comparing adolescent idiopathic scoliosis (AIS) and adult idiopathic scoliosis (AdIS) patients following posterior spinal fusion (PSF). Methods: 425 female AIS and AdIS patients who were operated (between January 2015 to March 2020) using a dual attending surgeon strategy were stratified into G1 (AIS aged 10-16 years old) and G2 (AdIS > 20 years old). PSM analysis with one-to-one, nearest neighbor matching technique with match tolerance of 0.001 was used to matched 357 AIS patients to 68 AdIS patients. Operation duration, intraoperative blood loss (IBL), blood loss percentage, hemoglobin drift, blood salvaged, postoperative wound length, allogenic blood transfusion requirement, postoperative hospital stay, postoperative Cobb, correction rate and postoperative complications were documented and reported. Results: Following PSM, G1 and G2 each had 50 patients with comparable and balanced covariates. As anticipated, G2 patients were heavier, taller and had higher body mass index compared to G1 patients (P < 0.05). We could not find any significant differences in the perioperative outcome comparing this 2 groups. AIS and AdIS patients had similar operation duration (125.9 ± 27.2 min vs 127.3 ± 37.8 min), IBL (749.8 ± 315.7 ml vs 723.8 ± 342.1 ml) and length of hospital stay (3.3 ± 0.4 days vs 3.5 ± 0.8 days) (P > 0.05). Hemoglobin drift and amount of blood salvaged were comparable (P > 0.05). G2 had stiffer curves. There was a trend toward a lower correction rate in G2 in the immediate postoperative period, however it did not reach statistical significance (61.8 ± 11.2% vs. 66.3 ± 11.6%, P = 0.051). No patients required blood transfusion and none had any postoperative complications. Conclusion: Adolescent and adult female scoliosis patients had comparable perioperative outcome following PSF surgery that was carried out using a dual attending surgeon strategy. [ABSTRACT FROM AUTHOR]

Background Context: The implementation of a dual attending surgeon strategy had improved perioperative outcomes of idiopathic scoliosis (IS) patients. Nevertheless, the learning curve of a dual attending surgeon practice in single-staged posterior spinal fusion (PSF) surgery has not been established.Objective: To evaluate the surgical learning curve of a dual attending surgeon strategy in IS patients.Study Design: Retrospective study.Patient Sample: 415 IS patients (Cobb angle <90°) who underwent PSF using a dual attending surgeon strategy OUTCOME MEASURES: Primary outcomes included operative time, total blood loss, allogenic blood transfusion requirement, length of hospital stay and perioperative complication rate.Methods: Regression analysis using Locally Weighted Scatterplot Smoothing (LOWESS) method was applied to create the best-fit-curve between case number versus operative time and total blood loss in identifying cut-off points for the learning curve.Results: The mean Cobb angle was 60.8±10.8°. Mean operative time was 134.4±32.1 minutes and mean total blood loss was 886.0±450.6 mL. The mean length of hospital stay was 3.0±1.6 days. The learning curves of a dual attending surgeon strategy in this study were established at the 115th case (operative time) and 196th case (total blood loss) respectively (p<.001). In comparison of cases before and after the cut-off points, mean operative time reduced significantly from 147.2±36.5 minutes to 129.5±28.9 minutes and mean total blood loss reduced significantly from 1015.1±506.6 mL to 770.4±357.3 mL (p<.001). No allogenic blood transfusion was required and there were 7 perioperative complications (n=7/415, 1.7%) recorded.Conclusion: The learning curve of a dual surgeon strategy in single-staged PSF surgery based on operative time and total blood loss were established at 115th case and 196th case respectively (p<.001). [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 prospective, nonrandomized study.Objective: To evaluate the effectiveness of periodic intraoperative text messages (SMS) in reducing parental anxiety level during posterior spinal fusion (PSF) surgery for adolescent idiopathic scoliosis (AIS) patients.Summary Of Background Data: No studies have reported the use of intraoperative SMS to reduce level of anxiety in parents of patients who are undergoing AIS corrective surgery.Methods: Parents of 50 AIS patients were studied at two centers. Group 1 did not receive any SMS whereas those in Group 2 received periodic SMS. Parents' anxiety were assessed using a validated Visual Analog Scale for anxiety (VAS-A) and the anxiety component of the Hospital Anxiety Depression Score (HADS). The assessment was carried out at five different periods: (P1) 6 hours before the surgery; (P2) at separation in the operation theatre; (P3) 1 hour after commencement of surgery; (P4) immediately after completion of surgery; (P5) 1 day postsurgery.Results: A total of 96 parents (47 fathers, 49 mothers) were involved in this study. Both groups were comparable in terms of demographics and education level. The mean VAS for Group 1 peaked at P2 and the HADS scores peaked at P3. The anxiety level of Group 1 remained high at P2, P3, and P4. There was a steady decline in parental anxiety in Group 2 from P1 to P5. There were significantly lower mean VAS score and HADS score for both father and mother in Group 2 during P3 and P4. The mean HADS scores for parents in Group 1 at P2 and P3 were higher than 8, which indicate abnormal anxiety.Conclusion: The anxiety levels of parents receiving the SMS were significantly lower than parents who did not receive any messages. Thus, intraoperative SMS is an effective intervention to decrease parental anxiety of AIS patients undergoing PSF surgery.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Preoperative supine radiographs are mandatory in the new adult idiopathic scoliosis (AdIS) classification. Supine radiographs are easily reproducible and highly predictive of side bending radiographs. However, few studies evaluated the use of supine radiographs in predicting postoperative curve correction after posterior spinal fusion (PSF) in AdIS. To investigate the use of supine and side bending (SB) radiographs in predicting postoperative curve correction in AdIS patients who underwent PSF. Retrospective study. A total of 93 AdIS patients who underwent PSF between 2022 and 2023 were included. Demographic data were age, gender, height, weight, body mass index (BMI), Risser grade, Lenke curve types and Cobb angles. Main outcome measures were preoperative and immediate postoperative Cobb angle (proximal thoracic [PT], main thoracic [MT] and thoracolumbar/lumbar [TL/L] curves), Supine Cobb angle and Flexibility rate (PT, MT and TL/L), and Correction rate (PT, MT and TL/L). Correlation study was performed between Supine Cobb angle vs postoperative Cobb angle for PT, MT and TL/L curves. A predictive formula was derived from the correlation plots. A total of 93 subjects were included in our study with a median age of 24.7 years and comprised of 80 females (86.0%). Preoperative Supine Cobb angle (r =0.835, r =0.881, r =0.767, p<.001) and preoperative SB Cobb angle (r =0.815, r =0.872, r =0.801, p<.001) showed similar strong positive correlation with postoperative PT, MT and TL/L Cobb angle, but preoperative Supine Cobb angle had slightly stronger correlation in PT and MT, whereas preoperative SB Cobb angle had stronger correlation in TL/L curve. Using the derived predictive formulae, there was a significant, strong, positive correlation between the predicted value and actual value of postoperative standing Cobb angle, (r=0.852, p<.001), with 71.0% of the patients had predicted postoperative Cobb angle from the supine radiographs within 5° of the actual value. Both supine radiographs and side bending radiographs had strong predictability of the postoperative Cobb angle for PT, MT and TL/L curves. In 71.0% of patients, the actual postoperative Cobb angle was within 5° of the predicted postoperative Cobb angle using the predictive formulae. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective study.Objective: To assess the learning curve of a dual attending surgeon strategy in severe adolescent idiopathic scoliosis patients.Summary Of Background Data: The advantages of a dual attending surgeon strategy in improving the perioperative outcome in scoliosis surgery had been reported. However, the learning curve of this strategy in severe scoliosis had not been widely studied.Methods: A total of 105 patients with adolescent idiopathic scoliosis with Cobb angle of 90° or greater, who underwent posterior spinal fusion using a dual attending surgeon strategy were recruited. Primary outcomes were operative time, total blood loss, allogeneic blood transfusion requirement, length of hospital stay from time of operation and perioperative complications. Cases were sorted chronologically into group 1: cases 1 to 35, group 2: cases 36 to 70, and group 3: case 71 to 105. Mean operative time (≤193.3 min), total blood loss (≤1612.2 mL), combination of both and allogeneic blood transfusion were the selected criteria for receiver operating characteristic analysis of the learning curve.Results: The mean Cobb angle was 104.5° ± 12.3°. The operative time, total blood loss, and allogeneic blood transfusion requirement reduced significantly for group 1 (220.6 ± 54.8 min; 2011.3 ± 881.8 mL; 12 cases) versus group 2 (183.6 ± 36.7 min; 1481.6 ± 1035.5 mL; 3 cases) and group 1 versus group 3 (175.6 ± 38.4 min; 1343.7 ± 477.8 mL; 3 cases) (P < 0.05). There were six perioperative complications. Fifty-seven cases were required to achieve the preset criteria (mean operative time and mean total blood loss) (area under the curve 0.740; P < 0.001; sensitivity 0.675; specificity 0.662).Conclusion: There was significant improvement in operative time and total blood loss when comparing group 1 versus group 2 and group 1 versus group 3. The cut-off point for the learning curve was 57 cases when the preset criteria were fulfilled (≤193.3 min operative time and ≤1612.2 mL of total blood loss).Level of Evidence: 4. [ABSTRACT FROM AUTHOR]

Study Design: Prospective study.Objective: To determine the parents'/patients' perception on the informed consent process prior to posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) patients.Summary Of Background Data: Understanding parents/patients perspective on the process is important in order to achieve the goal of consent and prevent medico-legal implications.Methods: Fifty AIS patients operated between August 2019 and November 2019 were prospectively recruited. Parents'/patients' perceptions on three sections were evaluated: the process of the informed consent, specific operative risk which they were most concerned with and the accountability of surgeons for the surgical risks. These data were ranked and scored using a 5-point Likert Scale. Preferences were reported in mean and standard deviation. Differences in terms of preferences were studied using One-way analysis of variance (ANOVA) analysis and deemed significant when P < 0.05.Results: There were 30 females (60.0%) and 20 males (40.0%) with a mean age of 41.8 ± 10.6 years. Majority of parents/patients preferred the inform consent to be explained more than once (P = 0.021), once during clinic consultation and once during admission (4.2 ± 1.0). Consent taking by both attending surgeons was preferred (4.5 ± 0.6) compared with other healthcare providers, P < 0.001. Death (60.0%) and neurological deficit (30.0%) were the two most concerned surgical risks. Parents/patients would still hold the surgeon accountable for any complications despite signing the informed consent and they felt that surgeons were directly responsible for screw-related injuries (3.9 ± 0.9), neurological injury (3.8 ± 0.9), and intraoperative bleeding (3.7 ± 0.9).Conclusion: Parents/patients preferred the attending surgeons to personally explain the informed consent, more than once with the use of visual aid. They would still hold the surgeons accountable when complications occur despite acceptance of the informed consent.Level Of Evidence: 2. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective study.Objective: To investigate the relationship between a +ve postoperative Upper Instrumented Vertebra (UIV) (≥0°) tilt angle and the risk of medial shoulder/neck and lateral shoulder imbalance among Lenke 1 and 2 Adolescent Idiopathic Scoliosis (AIS) patients following Posterior Spinal Fusion.Summary Of Background Data: Current UIV selection strategy has poor correlation with postoperative shoulder balance. The relationship between a +ve postoperative UIV tilt angle and the risk of postoperative shoulder and neck imbalance was unknown.Methods: One hundred thirty-six Lenke 1 and 2 AIS patients with minimum 2 years follow-up were recruited. For medial shoulder and neck balance, patients were categorized into positive (+ve) imbalance (≥+4°), balanced, or negative (-ve) imbalance (≤-4°) groups based on T1 tilt angle/Cervical Axis measurement. For lateral shoulder balance, patients were classified into +ve imbalance (≥+3°) balanced, and -ve imbalance (≤-3°) groups based on Clavicle Angle (Cla-A) measurement. Linear regression analysis identified the predictive factors for shoulder/neck imbalance. Logistic regression analysis calculated the odds ratio of shoulder/neck imbalance for patients with +ve postoperative UIV tilt angle.Results: Postoperative UIV tilt angle and preoperative T1 tilt angle were predictive of +ve medial shoulder imbalance. Postoperative UIV tilt angle and postoperative PT correction were predictive of +ve neck imbalance. Approximately 51.6% of patients with +ve medial shoulder imbalance had +ve postoperative UIV tilt angle. Patients with +ve postoperative UIV tilt angle had 14.9 times increased odds of developing +ve medial shoulder imbalance and 3.3 times increased odds of developing +ve neck imbalance. Postoperative UIV tilt angle did not predict lateral shoulder imbalance.Conclusion: Patients with +ve postoperative UIV tilt angle had 14.9 times increased odds of developing +ve medial shoulder imbalance (T1 tilt angle ≥+4°) and 3.3 times increased odds of developing +ve neck imbalance (cervical axis ≥+4°).Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Study Design: A retrospective study.Objective: The aim of this study was to compare the perioperative outcome of posterior spinal fusion (PSF) between overweight (OW) adolescent idiopathic scoliosis (AIS) patients and the healthy-weight (HW) patients using propensity score matching analysis.Summary Of Background Data: Obesity was found to increase postoperative surgical complications compared with the nonobese group. In scoliosis correction surgery, association of OW and perioperative risks had been explored, but most studies were retrospective in nature.Methods: From 374 patients, two comparable groups were matched using propensity score matching analysis with one-to-one nearest neighbor matching and a caliper of 0.2. There were 46 HW and OW patients in each group. The main outcome measures were intraoperative blood loss, use of allogeneic blood transfusion, operative time, duration of hospital stay post-surgery, total patient-controlled analgesia (PCA) morphine usage, perioperative complications, side bending flexibility (SBF), and correction rate (%).Results: The mean age was 13.3 ± 1.7 and 13.2 ± 1.7 years for HW and OW groups, respectively. The majority of the patients were Lenke 1 curves; 32.6% (HW) and 26.1% (OW) with an average Cobb angle of 69.0 ± 19.1° and 68.8 ± 18.4° for each group, respectively. The two groups were comparable. The operation time was 145.2 ± 42.2 and 154.4 ± 48.3 minutes for HW and OW groups, respectively (P > 0.05). The intraoperative blood loss was almost similar in both groups; 955.1 ± 497.7 mL (HW group) and 1011.8 ± 552.7 mL (OW group) (P > 0.05). Total PCA morphine used was higher in OW group (30.4 ± 22.7 mg) than in the HW group (16.2 ± 11.3 mg). No complication was observed in HW group, while in OW group, one patient (2.2%) developed intraoperative seizure.Conclusion: OW AIS patients (≥85th percentile) had similar mean operative time, intraoperative blood loss, allogeneic transfusion rate, length of stay, and perioperative complications compared with HW AIS patients.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Study Design: Case report.Objective: To describe the technical difficulties on performing posterior spinal fusion (PSF) on a pacemaker-dependent patient with complete congenital heart block and right thoracic scoliosis.Summary Of Background Data: Congenital complete heart block requires pacemaker implantation at birth through thoracotomy, which can result in scoliosis. Corrective surgery in this patient was challenging. Height gain after corrective surgery may potentially cause lead dislodgement. The usage of monopolar electrocautery may interfere with the function of the implanted cardiac device.Methods: A 17-year-old boy was referred to our institution for the treatment of right thoracic scoliosis of 70°. He had underlying complete congenital heart block secondary to maternal systemic lupus erythematosus. Pacemaker was implanted through thoracotomy since birth and later changed for four times. PSF was performed by two attending surgeons with a temporary pacing inserted before the surgery. The monopolar electrocautery device was used throughout the surgery.Results: The PSF was successfully performed without any technical issues and complications. Postoperatively, his permanent pacemaker was functioning normally. Three days later, he was recovering well and was discharged home from hospital.Conclusion: This case indicates that PSF can be performed successfully with thoughtful anticipation of technical difficulties on a pacemaker-dependent patient with underlying congenital heart block.Level Of Evidence: 5. [ABSTRACT FROM AUTHOR]

Study Design: A prospective cohort study.Objective: The aim of this study was to determine the feasibility of an accelerated recovery protocol for Asian adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion (PSF).Summary Of Background Data: There has been successful implementation of an accelerated recovery protocol for AIS patients undergoing PSF in the western population. No similar studies have been reported in the Asian population.Methods: Seventy-four AIS (65 F, 9 M) patients scheduled for PSF surgery were recruited. The accelerated protocol encompasses preoperative regime, preoperative day of surgery counseling, intraoperative strategies, an accelerated postoperative rehabilitation and pain management regime. All patients were operated using a dual attending surgeon strategy. Outcome measures included pain scores at five time intervals, length of stay, and detailed recovery milestones. Any complications or readmissions during the first 4 months postoperative period were recorded.Results: Mean duration of operation was 2.2 ± 0.3 hours with a mean blood loss of 824.3 ± 418.2 mL. No patients received allogenic blood transfusion. The mean length of stay was 3.6 ± 0.6 days. Surgical wound pain score was 6.4 ± 2.1 at 12 hours, which reduced to 5.0 ± 2.0 at 60 hours. Abdominal pain peaked at 36 hours with pain scores 2.4 ± 2.9. First liquid intake was at 5.2 ± 7.5 hours, urinary catheter removal at 18.7 ± 4.8 hours, sitting up at 20.6 ± 9.1 hours, ambulation at 27.2 ± 0.5 hours, consumption of solid food at 32.2 ± 0.5 hours, first flatus at 39.0 ± 0.7 hours, and first bowel movement at 122.1 ± 2.0 hours. The complication rate was 1.4% due to superficial wound infection with one patient failed to comply with the accelerated protocol.Conclusion: An accelerated recovery protocol following PSF for AIS is feasible without increasing the complication or readmission rates. The total length of stay was 3.6 days and this is comparable with the outcome in western population.Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Study Design: A prospective cohort study.Objective: The aim of this study was to determine and evaluate the trajectory of surgical wound pain from day 1 to day 14 after posterior spinal fusion (PSF) surgery in patients with adolescent idiopathic scoliosis (AIS).Summary Of Background Data: Information regarding how the postoperative pain improves with time offers invaluable information not only to the patients and parents but also to assist the clinician in managing postoperative pain.Methods: AIS patients who were planned for elective PSF surgery from September 2015 to December 2015 were prospectively recruited into this study. All patients underwent a similar pain management regimen with patient-controlled anesthesia (PCA) morphine, acetaminophen, celecoxib, and oxycodone hydrochloride.Results: A total of 40 patients (36 F:4 M) were recruited. The visual analogue score (VAS) pain score was highest at 12 hours postoperation (6.0 ± 2.3). It reduced to 3.9 ± 2.2 (day 4), 1.9 ± 1.6 (day 7), and 0.7 ± 1.1 (day 14). The total PCA usage in all patients was 12.4 ± 9.9 mg (first 12 hours), 7.1 ± 8.0 mg (12 to 24 hours), 5.6 ± 6.9 (24-36 hours), and 2.1 ± 6.1 mg (36-48 hours). The celecoxib capsules usage was reducing from 215.0 ± 152.8 mg at 24 hours to 55.0 ± 90.4 mg on day 14. The acetaminophen usage was reducing from 2275 ± 1198 mg at 24 hours to 150 ± 483 mg at day 14. Oxycodone hydrochloride capsules consumption rose to the peak of 1.4 ± 2.8 mg on day 4 before gradually reducing to none by day 13.Conclusion: With an adequate postoperation pain regimen, significant pain should subside to a tolerable level by postoperative day 4 and negligible by postoperative day 7. Patient usually can be discharged on postoperative day 4 when the usage of PCA morphine was not required.Level Of Evidence: 2. [ABSTRACT FROM AUTHOR]

Study Design: A prospective study.Objective: The aim of this study was to analyze the proximal thoracic (PT) flexibility and its compensatory ability above the "potential UIV."Summary Of Background Data: Shoulder and neck imbalance can be caused by overcorrection of the main thoracic (MT) curve due to inability of PT segment to compensate.Methods: Cervical supine side bending (CSB) radiographs of 100 Lenke 1 and 2 patients were studied. We further stratified Lenke 1 curves into Lenke 1-ve: PT side bending (PTSB) < 15° (n = 33) and Lenke 1+ve: PTSB 15° to 24.9° (n = 37). The right side bending (RSB) and left side bending (LSB) angles were measured (T1-T6). Compensatory ability of the PT segment was analyzed with assumption of a "horizontal UIV" position.Results: From T1 to T6 vertebrae, the RSB angle values showed increasing positive values. The LSB angle, comparing Lenke 1-ve versus 2 and Lenke 1+ve versus 2, showed significant difference at T2 to T6. The LSB angle comparing Lenke 1-ve versus 1+ve achieved significant difference at T5 and T6. In Lenke 2 curves, >80.0% of cases of the PT segment were unable to compensate at T3-T6. In Lenke 1+ve curves, 78.4% were unable to compensate at T6, followed by T5 (75.7%), T4 (73.0%), T3 (59.5%), T2 (27.0%), and T1 (21.6%). In Lenke 1-ve curves, 36.4% of cases were unable to compensate at T6, followed by T5 (45.5%), T4 (45.5%), T3 (30.3%), T2 (21.2%), and T1 (15.2%). A significant difference between Lenke 1-ve and Lenke 1+ve was observed from T3 to T6. The difference between Lenke 1+ve and Lenke 2 curves was significant only at T2.Conclusion: The compensation ability and the flexibility of the PT segments of Lenke 1-ve and Lenke 1+ve curves were different. Lenke 1+ve curves demonstrated similar characteristics to Lenke 2 curves.Level Of Evidence: 3. [ABSTRACT FROM AUTHOR]

Study Design: Prospective clinical study.Objective: To analyze the amount of blood loss at different stages of Posterior Instrumented Spinal Fusion (PSF) surgery in adolescent idiopathic scoliosis (AIS) patients.Summary Of Background Data: Knowing the pattern of blood loss at different surgical stages may enable the surgical team to formulate a management strategy to reduce intraoperative blood loss.Methods: One hundred AIS patients who underwent PSF from January 2013 to December 2014 were recruited. The operation was divided into six stages; stage 1-exposure, stage 2-screw insertion, stage 3-release, stage 4-correction, stage 5-corticotomies and bone grafting, and stage 6-closure. The duration and blood loss at each stage was documented. The following values were calculated: total blood loss, blood loss per estimated blood volume, blood loss per minute, blood loss per vertebral level fused, and blood loss per minute per vertebral level fused.Results: There were 89 females and 11 males. The mean age was 17.0 ± 5.8 years old. Majority (50.0%) were Lenke 1 curve type. The mean preoperative major Cobb angle was 64.9 ± 15.0°. The mean number of levels fused was 9.5 ± 2.3 levels. The mean operating time was 188.5 ± 53.4 minutes with a mean total blood loss 951.0 ± 454.0 mLs. The highest mean blood loss occurred at stage 2 (301.0 ± 196.7 mL), followed by stage 4 (226.8 ± 171.2 mL) and stage 5 (161.5 ± 146.6 mL). The highest mean blood loss per minute was at stage 5 (17.1 ± 18.3 mL/min), followed by stage 3 (12.0 ± 10.8 mL/min). The highest mean blood loss per vertebral levels fused was at stage 2 (31.0 ± 17.7 mL/level), followed by stage 4 (23.9 ± 18.1 mL/level) and stage 5 (16.6 ± 13.3 mL/level).Conclusion: All stages were significant contributors to the total blood loss except exposure (stage 1) and closure (stage 6). Blood loss per minute and blood loss per minute per level was highest during corticotomies (stage 5), followed by release (stage 3). However, the largest amount of total blood loss occurred during screw insertion (stage 2).Level Of Evidence: 2. [ABSTRACT FROM AUTHOR]