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Study Design: A prospective web-based survey. Purpose: Although intraoperative neurophysiological monitoring (IONM) is critical in spine surgery, its usage is largely based on the surgeon's discretion, and studies on its usage trends in Asia–Pacific countries are lacking. This study aimed to examine current trends in IONM usage in Asia–Pacific countries. Overview of Literature: IONM is an important tool for minimizing neurological complications and detecting spinal cord injuries after spine surgery. IONM can be performed using several modalities, such as transcranial electrical stimulation-muscle evoked potentials (Tc-MEP) and somatosensory evoked potentials (SEP). Methods: Spine surgeons of the Asia–Pacific Spine Society were asked to respond to a web-based survey on IONM. The questionnaire covered various aspects of IONM, including its common modality, Tc-MEP details, necessities for consistent use, and recommended modalities in major spine surgeries and representative surgical procedures. Results: Responses were received from 193 of 626 spine surgeons. Among these respondents, 177 used IONM routinely. Among these 177 respondents, 17 mainly used SEP, whereas the majority favored Tc-MEPs. Although a >50% decrease is the commonly used alarm point in Tc-MEP, half of the Tc-MEP users had no protocols planned for such scenarios. Moreover, half of the Tc-MEP users experienced complications, with bite injuries being the most common. Most respondents strongly recommended IONM in deformity surgery for pediatric and adult populations and tumor resection surgery for intramedullary spinal cord tumors. Conversely, IONM was the least recommended in lumbar spinal canal stenosis surgery. Conclusions: Spine surgeons in Asia–Pacific countries favored IONM use, indicating widespread routine utilization. Tc-MEP was the predominant modality for IONM, followed by SEPs. [ABSTRACT FROM AUTHOR]

Objective: To compare construct stiffness of cortical screw (CS)-rod transforaminal lumbar interbody fusion (TLIF) construct (G2) versus pedicle screw (PS)-rod TLIF construct (G1) in the standardized porcine lumbar spine. Methods: Six porcine lumbar spines (L2–L5) were separated into 12 functional spine units. Bilateral total facetectomies and interlaminar decompression were performed for all specimens. Non-destructive loading to assess stiffness in lateral bending, flexion and extension as well as axial rotation was performed using a universal material testing machine. Results: PS and CS constructs were significantly stiffer than the intact spine except in axial rotation. Using the normalized ratio to the intact spine, there is no significant difference between the stiffness of PS and CS: flexion (1.41 ± 0.27, 1.55 ± 0.32), extension (1.98 ± 0.49, 2.25 ± 0.44), right lateral flexion (1.93 ± 0.57, 1.55 ± 0.30), left lateral flexion (2.00 ± 0.73, 2.16 ± 0.20), right axial rotation (0.99 ± 0.21, 0.83 ± 0.26) and left axial rotation (0.96 ± 0.22, 0.92 ± 0.25). Conclusion: The CS-rod TLIF construct provided comparable construct stiffness to a traditional PS-rod TLIF construct in a ‘standardized’ porcine lumbar spine model.

Purpose: This study aims to derive a formula to predict post-operative height increment in Lenke 1 and Lenke 2 adolescent idiopathic scoliosis (AIS) patients using preoperative radiological parameters. Methods: This study involved 70 consecutive Lenke 1 and 2 AIS patients who underwent scoliosis correction with alternate-level pedicle screw instrumentation. Preoperative parameters that were measured included main thoracic (MT) Cobb angle, proximal thoracic (PT) Cobb angle, lumbar Cobb angle as well as thoracic kyphosis. Side-bending flexibility (SBF) and fulcrum-bending flexibility (FBF) were derived from the measurements. Preoperative height and post-operative height increment was measured by an independent observer using a standardized method. Results: MT Cobb angle and FB Cobb angle were significant predictors ( p < 0.001) of height increment from multiple linear regression analysis ( R = 0.784, R 2 = 0.615). PT Cobb angle, lumbar, SB Cobb angle, preoperative height and number of fused segment were not significant predictors for the height increment based on the multivariable analysis. Increase in post-operative height could be calculated by the formula: Increase in height (cm) = (0.09 × preoperative MT Cobb angle) – (0.04 x FB Cobb angle) – 0.5. Conclusion: The proposed formula of increase in height (cm) = (0.09 × preoperative MT Cobb angle) − (0.04 × FB Cobb angle) – 0.5 could predict post-operative height gain to within 5 mm accuracy in 51% of patients, within 10 mm in 70% and within 15 mm in 86% of patients.

Study Design: Cross-sectional. Objectives: To evaluate the perception and satisfaction among adolescent idiopathic scoliosis (AIS) patients on Neck Tilt with Medial Shoulder Imbalance and Lateral Shoulder Imbalance. Methods: Lenke 1 and 2 AIS patients were stratified into 6 groups of preoperative/ postoperative Balanced (B), Lateral Shoulder Imbalance (LSI) (>2 cm), and Neck Tilt with Medial Shoulder Imbalance (NT) (Grade 3). Patients were interviewed using Modified Neck and Shoulder Appearance and SRS-22r questionnaires. T1 tilt, Cervical Axis (CA), Clavicle Angle (Cla-A) and Radiographic Shoulder Height (RSH) were measured. Results: A total of 120 Lenke 1 and 2 AIS patients were recruited. NT patients were aware and unhappy with their abnormal neck with medial shoulder appearances (P <.001). Similarly, LSI patients were aware and unhappy with their abnormal lateral shoulder appearances (P <.001). NT group had larger preoperative/ postoperative T1 tilt (9.2 ± 5.0°; 9.5 ± 5.3°) and CA (4.6 ± 3.1°; 7.0 ± 2.0°) (P <.01). LSI group had larger preoperative/ postoperative Cla-A (4.8 ± 2.8°; 4.0 ± 1.3°) and RSH (20.1 ± 9.4 mm; 17.0 ± 6.6 mm) (P <.001). Postoperative B group scored higher in overall SRS-22r scores, self-image and satisfaction domains (4.2 ± 0.3; 4.0 ± 0.5; 4.4 ± 0.5) while preoperative LSI scored the lowest comparatively (3.5 ± 0.4; 2.4 ± 0.5; 3.3 ± 0.5) (P <.001). Conclusion: NT and LSI were major concerns among AIS patients. Both NT and LSI groups were unhappy with their appearances. NT group had larger T1 tilt/ CA whereas LSI group had larger Cla-A/ RSH. Postoperative B group scored higher in overall SRS-22r scores, self-image and satisfaction domains. [ABSTRACT FROM AUTHOR]

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]