Does levelling of T1 tilt intra-operatively affect post-operative shoulder balance in adolescent idiopathic scoliosis patients?

INTRODUCTION: Previous studies have shown that T1 tilt is positively correlated with post-operative shoulder balance (SB). The aim of this study was to explore the role of intra-operative T1 tilt, among other shoulder parameters as a potential parameter to predict post-operative SB in adolescent idiopathic scoliosis (AIS) patients. METHODS: A retrospective review of AIS patients with structural thoracic curves with minimum 2 year follow up was conducted from a single tertiary center. Standing pre-operative, 1st erect, 1 year and 2-year follow-up; and intra-operative final prone radiographs were reviewed along with clinical data. Patients were stratified into 2 cohorts: Group A-Final intra-operative T1 tilt ≤5° and Group B-Final intra-operative T1 tilt >5°. These groups were compared for post-operative SB as a whole and separately for patients with baseline right or left shoulder high and if UIV was T2 or T3/T4. Patients with optimal SB (Radiographic shoulder height (RSH) <2 cm) at 2 years were compared to sub-optimal SB (RSH ≥ 2 cm) with respect to multiple SB variables. RESULTS: 55 patients (mean age 15.1 years-old, 43 F, mean BMI 22, mean thoracic Cobb-49.8°) were included. Based on Lenke curve types, there were 13 patients with type 1A, 10 patients with 1B, 12 patients with 1C, 7 patients with 2A, 4 patients with 2B and 9 patients with type 3C. T1 tilt was significantly correlated with RSH, Clavicle angle difference (CAD), First Rib Angle (FRA), and UIV tilt at first erect, 1-year, and 2-year post-op radiographs (p < 0.05 for all). When comparing groups, A and B, Group A patients showed significantly better restoration of their 2-year SB parameters; RSH (6.8 vs 11.8 mm, p = 0.01), CAD (3.9 vs 9.1 p < 0.001) and T1 tilt (4.7 vs 7.8° p = 0.01). Similar results were found for patients with baseline right shoulder high; RSH (p = 0.04), CAD (p < 0.001) and T1 tilt (p < 0.001) and whether UIV was T2 or T3/T4. Eight patients with sub-optimal SB had worse intra-operative T1 tilt (p = 0.03) compared to 47 patients with optimal SB despite no difference in MT Cobb correction (83.1 vs 79.8%, p = 0.57). CONCLUSION: Post-operative T1 tilt correlates with lateral shoulder parameters at first erect, 1 year, and 2-year radiographs. Therefore, T1 tilt can potentially be used as a surrogate to predict post-operative SB. Leveling intra-operative T1 tilt ≤5° is associated with better 2-year post-operative shoulder balance parameters irrespective of whether the UIV was T2 or T3/T4. Patients with sub-optimal SB at 2 years had worse final intra-operative T1 tilt despite similar percent correction of main thoracic curve for all patients.

Shoulder balance in Lenke type 2 adolescent idiopathic scoliosis: correlations among radiological indices, cosmetic indices, and patient-reported outcomes.

OBJECTIVE: The aim of this study was to investigate the correlation between radiological indices of shoulder balance (SB) and cosmetic indices of shoulder deformity in patients with Lenke type 2 adolescent idiopathic scoliosis (AIS) and to determine the extent to which patient-reported outcomes (PROs) correlate with these measurements. Current management decisions and outcomes for SB in AIS are primarily based on radiological measurements. It is crucial to understand how these radiological parameters and cosmetic indices relate to patient satisfaction. METHODS: The authors analyzed the preoperative radiological and photographic indices of SB, along with PROs, in patients with Lenke type 2 AIS. Lateral SB parameters included the radiological shoulder height (RSH) and clavicle angle, while medial SB parameters included the first rib angle and T1 tilt angle. Photographic indices included the shoulder height angle (SHA), axilla height angle (AHA), and the left/right trapezius angle (LRTA) ratio. The authors assessed the self-image, mental health, and total score domains of the Korean version of the 22-item Scoliosis Research Society questionnaire. RESULTS: In their analysis of Lenke type 2 patients, the authors found that correlation coefficients between radiological measurements and photographic indices ranged from -0.25 to 0.47, among which only lateral SB including clavicle angle and RSH showed a significant correlation with anterior and posterior photographic indices. No statistically significant correlations were found between radiological measurements and PROs. Anterior photographic indices including SHA and AHA significantly correlated with all three PROs (p < 0.05). CONCLUSIONS: Radiological shoulder parameters did not accurately reflect the perceived SB. Anterior photographic indices were reliable for evaluating clinical SB in patients with Lenke type 2 AIS and correlated with PROs. Spine surgeons may benefit from paying more attention to anterior photographic indices when making surgical decisions regarding clinical SB.

Correlation analysis and clinical significance of changes in upper thoracic vertebra tilt and clavicle angle pre- and post-operation.

The imbalance of the lateral shoulder is reflected by the clavicle angle (CA) in radiology. It remains unclear how to achieve postoperative lateral shoulder balance (LSB) after spinal deformity correction surgery. A retrospective analysis was conducted on AIS patients who underwent surgery by the same spine surgeon at our hospital from 2016 to 2020. A total of 110 patients with spinal deformity were included in the study to verify the correlation between the T1-T5 tilt angle and CA before and after surgery, as well as the relation-ship between the change in T1-T5 tilt angle before and after surgery and the change in CA before and after surgery. By comparing the correlation coefficients, it was found that there may not be a direct relationship between the pre- and postoperative tilt angles of T1-5 and CA, but their changes were closely related to the changes in CA. The change in T1 tilt angle after orthopaedic surgery was significantly correlated with the change in CA, with a correlation coefficient of 0.976, indicating a close relationship between T1 and the clavicle. As the vertebrae moved down, the correlation gradually decreased. In summary, this study suggests that there is a close relationship between T1-T5 and the clavicle and that the change in T1 tilt angle after spinal scoliosis correction surgery is significantly correlated with CA, which decreases as the vertebra moves down.

Pedicle Dysplasia in Proximal Thoracic Adolescent Idiopathic Scoliosis Curves: What are We Missing and What are its Possible Surgical Implications? An Observational Retrospective Study on 104 Patients.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To assess if pedicle dysplasia is present in proximal thoracic (PT), both structural and nonstructural, compared to main thoracic (MT) curves; and to assess if it is predictive of radiographic outcomes at minimum 2 years of follow-up. METHODS: A retrospective review of surgically-treated Adolescent Idiopathic Scoliosis (AIS) patients with Lenke 1-2-3-4 curves was performed. On preoperative CT-scan, at the apical vertebra, pedicle width on the concavity (PWc) and on the convexity (PWv) and Pedicle Dysplasia Index (PDI, defined as PWc/PWv) were measured. Preoperative and last follow-up (at least 2 years) x-rays were reviewed. RESULTS: 104 patients meeting the inclusion criteria were divided into Structural-PT (S-PT) and Nonstructural-PT (NS-PT) groups based on Lenke criteria. PWc (P < .001). And PDI (P < .001 for S-PT, P = .004 for NS-PT) were significantly smaller in the PT than in MT curves for both groups. PT-PWc significantly correlated with follow-up PT Cobb for both groups (P < .001 and P = .015 respectively). PT-PDI significantly correlated with follow-up PT-Cobb (P < .001), CA (P < .040) and T1 tilt (P < .002), only for NS-PT group. NS-PT patients with PWc PT <1 mm had higher RSHD (P = .021) and T1 tilt (P = .025) at follow-up. NS-PT patients with PDI PT <.3 had higher RSHD (P < .001), CA (P = .002) and T1 tilt (P = .003) at follow-up. CONCLUSION: S-PT and NS-PT curves show significant pedicle dysplasia on the concavity. Pedicle dysplasia significantly correlated with shoulder balance at follow-up, for NS-PT patterns. Patients with a PWc <1 mm or PDI <.30 are at particular risk of postoperative shoulder imbalance.

Flexibility-tilt agreement best predicts shoulder balance following posterior spine fusion for adolescent idiopathic scoliosis.

PURPOSE: We propose a novel concept, called flexibility-tilt agreement (FTA), which could be applied intra-operatively to improve shoulder balance following posterior spine fusion for Adolescent Idiopathic Scoliosis (AIS). We retrospectively applied this concept to a cohort with thoracic-only curves, seeking to: (1) evaluate the impact of FTA and other peri-operative variables on post-operative shoulder balance, and (2) evaluate deformity characteristics associated with achieving FTA. METHODS: A single-institution registry was queried for patients undergoing PSF from 2000 to 2017 with main thoracic and double thoracic curves with at least 2-year follow-up. Flexibility was defined as the Cobb angle of the unfused proximal thoracic curve (cephalad to chosen UIV) on pre-operative bender. Tilt refers to post-operative UIV tilt angle. FTA means these values cancel (Flexibility + Tilt = 0 ± 5°). Logistic regression was performed to determine the association between peri-operative variables and shoulder balance. RESULTS: One hundred and sixty-one patients were included, mean age 13.6 years old, and 47-month mean follow-up. FTA was achieved in 74 (46%) patients and was associated with post-operative (OR = 4.59) and final (OR = 6.98) medial shoulder balance with a threshold of 6° (AUC = 0.77, p = 0.038). FTA was the best predictor of shoulder balance of all tested variables. CONCLUSION: Patients that showed flexibility-tilt agreement, or FTA, had vastly increased odds of medial and lateral shoulder balance at a minimum of 2-year follow-up for all thoracic curves. Future studies can evaluate whether applying FTA to determine intra-operative corrective maneuvers prospectively leads to improvements in shoulder balance. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Morphology and deformity of the shoulder and pelvis in the entire spine radiographs of adolescent idiopathic scoliosis.

Background: To investigate the deformity and asymmetry of the shoulder and pelvis in adolescent idiopathic scoliosis (AIS) patients. Methods: This retrospective cross-sectional study enrolled 223 AIS patients with a right thoracic curve or left thoracolumbar/lumbar curve who underwent spine radiographs at the Third Hospital of Hebei Medical University between November 2020 and December 2021. The following parameters were measured: Cobb angle, clavicular angle, glenoid obliquity angle, acromioclavicular joint deviation, femoral neck-shaft projection angle, iliac obliquity angle, acetabular obliquity angle, coronal trunk deviation distance, and spinal deformity deviation distance. The Mann-Whitney U test, Kruskal-Wallis H test were used for inter-group comparisons, and Wilcoxon signed-rank test were used for intra-group left and right sides comparisons. Results: Shoulder and pelvic imbalances were found in 134 and 120 patients, respectively, and there were 87, 109, and 27 cases of mild, moderate, and severe scoliosis, respectively. Compared with mild scoliosis patients, the difference in the acromioclavicular joint offset on bilateral sides was significantly increased in moderate and severe scoliosis [11.04, 95% confidence interval (CI): 0.09-0.14 for mild, 0.13-0.17 for moderate, and 0.15-0.27 for severe scoliosis, P=0.004], and the difference in the femoral neck-shaft projection angle on bilateral sides was significantly enhanced with scoliosis aggravation (14.14, 95% CI: 2.34-3.41 for mild, 3.00-3.94 for moderate, and 3.57-6.43 for severe scoliosis, P=0.001). The acromioclavicular joint offset was significantly larger on the left than that on the right in patients with a thoracic curve or double curves (thoracic curve -2.75, 95% CI: 0.57-0.69 for the left and 0.50-0.63 for the right, P=0.006; double curve -3.27, 95% CI: 0.60-0.77 for the left and 0.48-0.65 for the right, P=0.001). The femoral neck-shaft projection angle was significantly larger on the left than right in patients with a thoracic curve (-4.46, 95% CI: 133.78-136.20 for the left and 131.62-134.01 for the right, P<0.001), but larger on the right than left in patients with thoracolumbar/lumbar curve (thoracolumbar -2.98, 95% CI: 133.75-136.70 for the left and 135.13-137.82 for the right, P=0.003; lumbar -3.24, 131.97-134.56 for the left and 133.76-136.26 for the right, P=0.001). Conclusions: In AIS patients, shoulder imbalance has a greater impact on coronal balance and spinal scoliosis above the lumbar segment, whereas pelvic imbalance has a greater impact on sagittal balance and spinal scoliosis below the thoracic segment.

Preoperative left shoulder elevation > 1 cm is predictive of severe postoperative shoulder imbalance in early onset idiopathic scoliosis patients treated with growth-friendly instrumentation.

PURPOSE: Prior research has demonstrated the influence of preoperative shoulder elevation (SE), proximal thoracic curve magnitude, and upper instrumented vertebra (UIV) on shoulder balance after PSF for AIS. Our purpose was to evaluate the impact of these factors on shoulder balance in early onset idiopathic scoliosis (EOIS) patients treated with growth-friendly instrumentation. METHODS: This was a multicenter retrospective review. Children with EOIS treated with dual TGR, MCGR, or VEPTR and minimum 2-year follow-up were identified. Demographics and radiographic/surgical data were collected. RESULTS: 145 patients met inclusion criteria: 74 had right SE (RSE), 49 left SE (LSE), and 22 even shoulders (EVEN) preoperatively. Mean follow-up was 5.3 years (range, 2.0-13.1 years). The LSE group had a larger pre-index mean main thoracic curve (p = 0.021) but no difference was observed between groups at the post-index or most recent timepoints. RSE patients with UIV of T2 were more likely to have balanced shoulders post-index than patients with UIV of T3 or T4 (p = 0.011). Pre-index radiographic shoulder height (RSH) was predictive of post-index shoulder imbalance ≥ 2 cm in the LSE group (p = 0.007). A ROC curve showed a cut-off of 1.0 cm for RSH. 0/16 LSE patients with pre-index RSH < 1.0 cm had post-index shoulder imbalance ≥ 2 cm compared to 8/28 (29%) patients with pre-index RSH > 1.0 cm (p = 0.006). CONCLUSION: Preoperative LSE > 1.0 cm is predictive of shoulder imbalance ≥ 2 cm after insertion of TGR, MCGR, or VEPTR in children with EOIS. In patients with preoperative RSE, UIV of T2 resulted in a higher likelihood of balanced shoulders postoperatively.

A Novel Method for Predicting Ideal Postoperative Upper Instrumented Vertebra Tilt to Prevent Lateral Shoulder Imbalance after Scoliosis Correction Surgery.

Lateral shoulder imbalance (LSI) is reflected radiologically by the clavicle angle (CA). How to achieve postoperative lateral shoulder balance (LSB) after scoliosis correction surgery remains unclear. In the current study, by using the preoperative upper instrumented vertebra (UIV) tilt, the CA, the flexibility between T1 and the UIV, and the ideal postoperative UIV tilt was predicted based on the following formula: ideal postoperative UIV tilt = preoperative UIV tilt-the flexibility between T1 and UIV-preoperative CA. The reliability of the formula was verified through a retrospective analysis, and 76 scoliosis patients were enrolled. The feasibility of this method was verified through a prospective analysis, and 13 scoliosis patients were enrolled. In the retrospective study, there was a significant correlation between the difference in the actual and ideal postoperative UIV tilt values and the postoperative CA, with correlation coefficients in the whole, LSI, and LSB groups of 0.981, 0.982, and 0.953, respectively (p < 0.001). In the prospective study, all patients achieved satisfactory LSB. Using the formula preoperatively to predict an ideal postoperative UIV tilt and controlling the intraoperative UIV tilt with the improved crossbar technique may be an effective digital method for achieving postoperative LSB and has important clinical significance.

Preoperative Less Right Shoulder Elevation Had a Higher Risk of Postoperative Shoulder Imbalance When Main Thoracic Curve Shows Higher Correction Regardless of the Upper Instrumented Vertebra Level for Patients with Adolescent Idiopathic Scoliosis Lenke Type 1.

STUDY DESIGN: This is a retrospective study. PURPOSE: This study aimed to investigate the incidence of and risk factors for postoperative shoulder imbalance (PSI) in patients with Lenke type 1. OVERVIEW OF LITERATURE: PSI is a complication resulting in poor self-image and satisfaction in adolescent idiopathic scoliosis (AIS) patients. METHODS: We examined the data of AIS patients with Lenke type 1 curves who underwent posterior fusion surgery in a retrospective manner. PSI was defined as a 2-year postoperative absolute radiographic shoulder height (RSH) of ≥2 cm. Patients were divided into two groups based on the presence of PSI and the level of their upper instrumented vertebra (UIV) (UIV at T2 or T3 [U-UIV] or UIV below T3 [L-UIV]). The radiographic parameters and clinical outcomes were compared, and the cutoff values of risk factors were identified by multivariate analysis. RESULTS: Of 104 patients, 21 (20.2%) had left shoulder elevation PSI. The PSI group had a significantly greater preoperative RSH (-5.1 mm vs. -14.3 mm) and main thoracic (MT) curve correction rate (77.3% vs. 69.1%) than the non-PSI group. The PSI incidence did not differ between the U-UIV and L-UIV groups. Multivariate analysis identified preoperative RSH and the MT curve correction rate as independent risk factors for PSI. The receiver operating characteristic curve analysis identified the preoperative RSH cutoff value as -6.5 mm and MT curve correction rate cutoff value as 76.9%. CONCLUSIONS: Even in AIS patients with Lenke type 1 curves, the incidence of PSI was relatively high (20.2%). Patients with preoperative lower right shoulder elevation (i.e., RSH >-6.5 mm) had a higher risk of PSI regardless of UIV level when the MT curve showed a higher correction rate (i.e., correction rate >76.9%).

Preoperative "Cervical Axis" Deviation Increases the Risk of Distal Adding-On Following Surgery in Lenke 1 and 2 Adolescent Idiopathic Scoliosis Patients.

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.

Incidence and risk factors of postoperative medial shoulder imbalance in Lenke Type 2 adolescent idiopathic scoliosis with lateral shoulder balance.

BACKGROUND: In clinical practice, there are a significant percentage of Lenke 2 AIS patients suffered from medial shoulder imbalance (MSI) despite achieving good lateral shoulder balance (LSB) following surgery. However, there are few studies evaluating the features of the medial shoulder. The objective of this study was to determine the incidence and independent risk factors of MSI with LSB after Lenke 2 AIS corrective surgery. METHODS: One hundred and twenty Lenke 2 AIS patients with LSB at the last follow-up were reviewed from 2009 to 2018. Preoperative, and 3-month and the last postoperative follow-up radiographs were measured using a number of specific measurements. At the last follow-up, patients were divided into medial shoulder balance (MSB) group and the MSI group according to whether the T1 tilt was greater than 3°. A stepwise multiple linear regression analysis was used to examine the independent risk factors for MSI. Scoliosis Research Society (SRS)-30 questionnaire was used to assess clinical outcomes. RESULTS: Up to 69.2% of patients suffered from MSI with LSB after Lenke Type 2 AIS corrective surgery. Multiple regression showed that postoperative upper instrumented vertebra tilt (UIVt), proximal thoracic curve (PTC), the ratio of PTC and main thoracic curves (PTC/MTC) and T2 vertebra rotation ratio (T2-VR) were significant predictors for MSI (UIVt: b = 0.398, p < 0.001; PTC/MTC: b = 2.085, p < 0.001; PTC: b = 0.155, p < 0.001; T2-VR: b = 3.536, p = 0.008; adjusted R2 = 0.711). 72 patients completed the SRS-30 questionnaire survey, and the MSB group were scored the higher (p ≤ 0.001) in self-image domain (4.18 ± 0.43 vs. 3.70 ± 0.35), satisfaction domain (4.39 ± 0.54 vs. 3.95 ± 0.46) and total average (4.31 ± 0.23 vs. 4.11 ± 0.19). CONCLUSION: Although the patients with Lenke 2 AIS achieve LSB after corrective surgery, up to 69.2% of them suffered from MSI. Postoperative UIVt, PTC, PTC/MTC and T2-VR were significant predictors for MSI. Sufficient correction of these variables may facilitate the achievement of MSB.

Achieving Shoulder Balance Using Medial and Lateral Radiological Measures in Adolescent Idiopathic Scoliosis.

Background: Research has shown that postoperative shoulder imbalance is a common problem after spinal fusion in adolescent idiopathic scoliosis (AIS). The best radiographic predictor has not yet been determined and results are inconsistent. This study was to investigate whether using medial and lateral shoulder parameters can effectively achieve postoperative shoulder balance. Methods: A prospective database of AIS undergoing posterior spinal fusion were reviewed. Patient demographics and radiological parameters including radiographic shoulder height (RSH), clavicle angle, T1-tilt and first-rib angle at baseline, 6 weeks and last minimal follow up of 2 years were recorded. Correlations between radiological parameters were assessed using Pearson's correlation coefficients. Multivariable linear models identified predictors associated with increased RSH. Results: 219 patients (mean age:13.7 years; 81.7% female) were included. The mean follow-up time was 2.8 years (range:2.0-7.0). The mean RSH at baseline, 6 weeks and last follow up was improved significantly at 95.8%. Preoperative (r=0.8; p<0.001) and post-operative measurements of RSH at 6-week (r=0.9; p<0.001) and last follow up (r=0.9; p<0.001) correlated strongly with clavicle angle measured at respective time-points. In a multivariable linear model, we noted marginal increase in clavicle angle (+4.3°; p<0.001) to be associated with increased RSH. On the contrary, first rib angle and T1-tilt demonstrated moderate to weak correlation with RSH. Conclusion: Clavicle angle is strongly consistent with RSH. First rib angle and T1-tilt as demonstrate medial shoulder balance are moderate to weak correlation. Leveling T1 tilt and first rib angle do not guarantee the postoperative shoulder balance. Level of Evidence: IV.

Increased proximal vertebral rotation is associated with shoulder imbalance after posterior spinal fusion for severe adolescent idiopathic scoliosis.

PURPOSE: Residual shoulder imbalance is associated with suboptimal outcomes following the surgical correction of adolescent idiopathic scoliosis (AIS) including poor patient satisfaction. In this retrospective study, we evaluate the radiographic parameters and the relationship between the global and local indices of spinal alignment with shoulder balance pre- and postoperatively utilizing EOS imaging and 3D reconstruction. METHODS: A retrospective radiographic analysis was performed on patients with AIS, treated with posterior spinal fusion. Postoperative radiographs were obtained immediately following surgery, at 6 months and final follow-up over 2 years postoperatively. 3D Radiographic measurements included in the coronal plane radiographic shoulder height difference (RSHD), proximal thoracic Cobb angle (PT) and main thoracic Cobb (MT), in the sagittal plane T4-T12 kyphosis, T12-L5 lordosis, in the axial plane proximal thoracic (PT AVR) and main thoracic apical vertebral rotation (MT AVR). RESULTS: Sixty-six patients were included (63 females) with an average main thoracic curvature of 76 degrees. RSHD averaged 14 mm ± 14 preoperatively, -15 mm ± 12 postoperatively, -8.5 mm ± 11 at 6 months, and -8.3 mm ± 8.7 at final follow-up, respectively. Statistical analysis revealed a significant correlation between RSHD and proximal thoracic Cobb angle, between RSHD and proximal thoracic apical vertebral rotation (PTAVR) (r > 0.20, p < 0.05). CONCLUSION: The significant correlation presented in this study suggests that PT Cobb angle and PT AVR are involved in postoperative shoulder imbalance. THE LEVEL OF EVIDENCE: Level 4.

Should the upper end vertebra be selected as the upper instrumented vertebra in patients with Lenke type 5C adolescent idiopathic scoliosis?

STUDY DESIGN: Retrospective study. PURPOSE: The upper end vertebra (UEV) is often selected as the upper instrumented vertebra (UIV) in patients with adolescent idiopathic scoliosis (AIS) with Lenke type 5C curves; however, the effect of adjusting UIV selection one level toward the cranial side (UEV + 1) is unknown. Therefore, this study aimed to assess the effect of UIV extension on scoliosis correction and global alignment in patients with the UIV as the UEV and UEV + 1. METHODS: Data of 52 patients with AIS with Lenke type 5C curves who underwent selective thoracolumbar/lumbar (TL/L) fusion with a minimum follow-up period of 2 years were retrospectively analyzed. The patients were divided according to the UIV in relation to the UEV: the UEV and UEV + 1 groups. Radiographic parameters and clinical outcomes were compared between the two groups. RESULTS: Among the 52 patients, 24 and 28 were included in the UEV and UEV + 1 group. Baseline data showed no intergroup differences except for the UIV level. While the UEV + 1 group showed a significantly greater TL/L curve correction (72.9% vs. 62.8%, p < 0.05) and a lower UIV tilt, it showed a significantly greater absolute value of radiographic shoulder height (RSH) (- 7.9 vs. - 0.9 mm, p < 0.05) and coronal balance (- 11.0 mm vs - 4.8 mm, p < 0.05) at 2 years postoperatively. The rate of post-operative shoulder imbalance (RSH ≥ 2 cm) was significantly higher in the UEV + 1 than in the UEV group. No intergroup differences were observed in the sagittal alignment and patient outcomes between the two groups. CONCLUSION: When the UIV was selected as the UEV + 1, correction of the TL/L curve improved; however, it increased the risk of shoulder and coronal imbalance. There is no clinical benefit observed in terms of extending the UIV to the UEV + 1; therefore, the UIV should be selected as the UEV to maintain harmonious global alignment. LEVEL OF EVIDENCE: Level 3.

Does Obesity Affect Preoperative Shoulder Balance in Adolescent Idiopathic Scoliosis?

BACKGROUND: Obese patients with adolescent idiopathic scoliosis (AIS) have been shown to present with larger curve magnitudes preoperatively. However, the effect of obesity on shoulder balance in AIS remains unknown. The purpose of our study was to determine if overweight and obese patients with AIS have worse radiographic shoulder balance on initial presentation when compared with normal weight patients. METHODS: AIS patients <18 years old, with Lenke 1 or 2 curves, who underwent a posterior spinal fusion between March 2013 and December 2018 were retrospectively evaluated. BMI-for-age percentiles as defined by the Center for Disease Control and Prevention were used: obese (≥95th percentile), overweight (85th to <95th percentile), and normal weight (5th to <85th percentile). Shoulder height was measured via the radiographic shoulder height (RSH) method, with an RSH ≤ 1 cm considered balanced. The primary outcome was preoperative shoulder balance. Secondary outcomes included postoperative shoulder balance, major curve correction, and UIV selection. RESULTS: One hundred eighty-four patients (116 [63%] normal weight and 68 [37%] overweight/obese) were included. The mean age at surgery was 13.1 ± 2 years, and mean follow-up was 17.4 ± 13 months. Preoperative shoulder imbalance was significantly greater in the overweight/obese group compared to the normal weight group (1.9 ± 1 cm vs. 1.5 ± 1 cm, p = 0.04). The odds ratio of presenting with unbalanced shoulders was 2.0 (95% CI: 1.02-3.83, p = 0.04) for the overweight/obese group. No significant differences were found for postoperative shoulder balance, UIV selection, or major curve correction. CONCLUSIONS: Overweight and obese patients with AIS are twice as likely to present with unbalanced shoulders preoperatively; however, this difference is not clinically relevant with a mean difference of 0.4 cm between cohorts. Finally, the preoperative BMI percentile did not show a significant effect on the chosen UIV or curve magnitude correction. LEVEL OF EVIDENCE: Level III: this is a retrospective case-control study.

Shoulder Imbalance in Adolescent Idiopathic Scoliosis: A Systematic Review of the Current State of the Art.

Background: Shoulder imbalance (SI) is among the most rated manifestations of adolescent idiopathic scoliosis (AIS) pointed to by patients and spine surgeons. It serves as a criterion to assess the outcome of scoliosis surgery and is also a cause of dissatisfaction for the patients postoperatively. Despite the availability of multiple studies on this issue, a comprehensive survey of the risk factors and preventive measures has yet to be elucidated. The present study aimed to highlight the most recent approach to the evaluation and management of SI, as well as medical counseling about the expectations and limitations of the surgery. Methods: A systematic literature review using electric databases was conducted, including PubMed, Embase, the Cochrane Library, and Google Scholar, with a well-defined search strategy on SI definition, risk factors, and preventive and surgical recommendations. Results: A total of 69 articles were identified; SI > 2 cm was the most used cut-off, and its risk factors included the main thoracic Cobb angle > 80˚, preoperative level shoulder, high left shoulder, and higher Risser grade. The most stated strategies to preclude SI were the sufficient correction of the proximal thoracic curve, and moderate correction of the main thoracic and lumbar curve (LC). Conclusion: Shoulder imbalance should be prevented not only for appearance or satisfaction but also for possible complications such as distal adding-on, new LC progression, or trunk shift postoperatively in AIS patients.

Evaluation of shoulder balance in early onset scoliosis after definitive fusion and comparison with adolescent idiopathic scoliosis shoulder balance.

STUDY DESIGN: The Children Spine Study Group registry was queried for early onset scoliosis (EOS) patients who had final definitive spinal fusion after their scoliosis was managed with either growing rods or VEPTR. The Harms Study Group registry was queried for adolescent idiopathic scoliosis (AIS) patients who had definitive fusion OBJECTIVE: The goal is to assess shoulder alignment in EOS patients after a definitive fusion and how these radiographic outcomes relate to the more familiar situation of post-definitive fusions shoulder alignment in AIS patients. BACKGROUND: EOS is a challenging pathology to manage. Numerous components are important in the success of spinal surgery for this population. Shoulder balance is a one of the components that is easily seen by the patient. Recently, the importance of its relationship to patient satisfaction has received greater attention. METHODS: Sample size: n = 145 (EOS (n = 34) and AIS (n = 111)). Shoulder balance parameters (SBP) of clavicular angle (CA), coracoid height difference (CHD), clavicular tilt angle difference (CTAD), and clavicle-rib cage intersection difference (CRID) measurements were measured from the reviewed radiographs and documented pre-definitive, post-definitive and 2-year follow-up measures. Shoulder balance parameters were compared between EOS and AIS cohorts at documented intervals. RESULTS: EOS mean pre-definitive fusion SBPs (CA, CTAD, CRID, CHD) were significantly higher compared to AIS, p = 0.004, 0.003, < 0.001, < 0.001, respectively. Significant post-definitive fusion corrections were noticed for CTAD (0.01), CHD (0.01), nearly significant CA (0.07), non-significant CRID in EOS patients. In AIS patients, no significant corrections were noticed for CA, CTAD, CHD and but significant for CRID (0.02). At post-definitive and 2-year follow-up, CA, CRID, CHD were not significant between cohorts, but CTAD (< 0.01) was significantly higher in EOS cohort at final follow-up. CONCLUSION: Post-definitive and 2-year follow-up shoulder balance for EOS patients was not significantly different from AIS patients. LEVEL OF EVIDENCE: III.

Shoulder balance in patients with Lenke type 1 and 2 idiopathic scoliosis appears satisfactory at 2 years following anterior vertebral body tethering of the spine.

BACKGROUND: Shoulder balance is an important factor for patient satisfaction following surgery for idiopathic scoliosis (IS). There is no literature reporting the effect of anterior vertebral body tethering (AVBT) on shoulder balance. The purpose of this study was to report the prevalence of postoperative shoulder imbalance in patients undergoing AVBT for IS. METHODS: In this retrospective case series, patients enrolled in a multicenter scoliosis registry who underwent AVBT from 2013 to 2017 in two Canadian centers were identified. The primary outcome was shoulder imbalance, defined as an absolute radiographic shoulder height of > 2 cm, at 2 years postoperatively (follow-up range: 22-30 months). Clavicular angle and T1 tilt angle were also investigated. RESULTS: Of the 50 patients identified (92% female; preoperative age: 11.9 ± 1.4 years), there were 43 (86%) patients with Lenke 1 and 7 (14%) patients with Lenke 2 curves. The mean Cobb angles of the proximal thoracic and main thoracic curves were 22.8° ± 8.8° and 49.4° ± 8.5° preoperatively and 13.1° ± 7.5° and 24.9° ± 9.5° at a mean follow-up time of 2.1 years. Absolute clavicular angle and T1 tilt angle were 2.8° ± 2.2° and 4.8° ± 3.5° preoperatively and 2.2° ± 1.7° and 4.7° ± 4.2° at 2-year follow-up. Preoperatively, absolute shoulder height averaged 15.6 ± 10.4 mm, and 15 (30%) patients had shoulder imbalance. At 2-year follow-up, absolute shoulder height averaged 11.2 ± 8.3 mm, and 8 (16%) patients had shoulder imbalance. Of the patients who had acceptable shoulder balance preoperatively, 4 (11.4%) became imbalanced at 2 years postoperatively. CONCLUSION: Postoperative shoulder imbalance in this early group of patients with IS undergoing AVBT was seen in 16% of patients, a reduction from 30% preoperatively. These results likely reflect the potential of the proximal thoracic curve to correct spontaneously following AVBT. LEVEL OF EVIDENCE: Level III.

Evaluation of changes in shoulder balance and prediction of final shoulder imbalance during growing-rod treatment for early-onset scoliosis.

BACKGROUND: Obtaining and maintaining final shoulder balance after the entire treatment course is essential for early-onset scoliosis (EOS) patients. The relatively small number of growing-rod (GR) graduates who complete final fusion has resulted in an overall paucity of research on the GR treatment of EOS and a lack of research on the shoulder balance of EOS patients during GR treatment. METHODS: Twenty-four consecutive patients who underwent GR treatment until final fusion were included. Radiographic shoulder balance parameters, including the radiographic shoulder height (RSH), clavicle angle (CA), and T1 tilt angle (T1T), before and after each step of the entire treatment were measured. Shoulder balance changes from GR implantation to the last follow-up after final fusion were depicted and analysed. Demographic data, surgical-related factors, and radiographic parameters were analysed to identify risk factors for final shoulder imbalance. The shoulder balance of patients at different time points was further analysed to explore the potential effect of the series of GR treatment steps on shoulder balance. RESULTS: The RSH showed substantial improvement after GR implantation (P = 0.036), during the follow-up period after final fusion (P = 0.021) and throughout the entire treatment (P = 0.011). The trend of change in the CA was similar to that of the RSH, and the T1T improved immediately after GR implantation (P = 0.037). Further analysis indicated that patients with shoulder imbalance before final fusion showed significantly improved shoulder balance after fusion (P = 0.045), and their RSH values at early postfusion and the final follow-up did not show statistically significant differences from those in the prefusion shoulder balance group (P > 0.05). Early postfusion shoulder imbalance (odds ratio (OR): 19.500; 95% confidence interval (CI) = 1.777-213.949; P = 0.015) was identified as an independent risk factor for final shoulder imbalance. CONCLUSIONS: Shoulder balance could be improved by GR implantation but often changes during the multistep lengthening process, and the final result is relatively unpredictable. Final fusion could further adjust the prefusion shoulder imbalance. Focusing on the prefusion shoulder balance of GR graduates and providing patients with early shoulder balance after fusion might be necessary.

Surgeons lack of agreement on determining preoperative radiographic and clinical shoulder balance in adolescent and adult idiopathic scoliosis patients.

PURPOSE: Preoperative shoulder balance is an important factor in determining the upper instrumented vertebrae (UIV). In adolescent and adult idiopathic scoliosis (AIS/AdIS) patients, we studied the intraobserver and interobserver reliability of spinal surgeons' assessment of preoperative shoulder balance using X-rays (XR) and anterior/posterior photographs. METHODS: An observational review of a prospective multicenter database (AIS Lenke Type 1/5/6) and prospective single-institution database (AdIS) was conducted. Ten spine surgeons reviewed AIS cases; 12 spine surgeons reviewed AdIS cases. Surgeons rated the higher shoulder: left/right/same/unsure. Reliability was calculated using Fleiss' kappa coefficient. RESULTS: Among 145 Type 1 AIS cases, intraobserver reliability was moderate-to-substantial: XR (κ = 0.59), anterior photographs (κ = 0.68), posterior photographs (k = 0.65). Interobserver reliability was fair to moderate for XR (κ = 0.31), anterior photographs (κ = 0.20), and posterior photographs (κ = 0.30). Among 52 Type 5/6 AIS cases, intraobserver reliability was substantial: XR (κ = 0.70), anterior photographs (κ = 0.76), posterior photographs (κ = 0.71). Interobserver reliability was fair to moderate for XR (κ = 0.49), anterior photographs (κ = 0.47), and posterior photographs (κ = 0.36). Among 66 AdIS cases, intraobserver reliability was substantial: XR (κ = 0.68), anterior photographs (κ = 0.67), posterior photographs (κ = 0.69). Interobserver reliability was moderate for XR (κ = 0.45), anterior photographs (κ = 0.43), posterior photographs (κ = 0.49). Within Type 1 AIS patients, attendings had better intraobserver reliabilities compared to fellows using X-rays (κ = 0.61 vs. 0.53), yet no effect of surgeon experience was seen with clinical photographs. CONCLUSION: Though surgeons' ability to agree with themselves was moderate to substantial, surgeons' ability to agree with each other was fair to moderate. Combined measures to assess preoperative shoulder balance are needed for UIV selection.