Selective fusion in adolescent idiopathic scoliosis: a radiographic evaluation of risk factors for imbalance

Coronal decompensation following thoracic vertebral body tethering in idiopathic scoliosis

PURPOSE

Post-operative coronal decompensation (CD) continues to be a challenge in the treatment of adolescent idiopathic scoliosis (AIS). CD following selective spinal fusion has been studied. However, there is currently little information regarding CD following Vertebral Body Tethering (VBT). Thus, the goal of this study is to better understand the incidence and risk factors for CD after VBT.

METHODS

Retrospective review of a prospective multicenter database was used for analysis. Inclusion criteria were patients undergoing thoracic VBT, a minimum 2-year follow-up, LIV was L1 or above, skeletally immature (Risser ≤ 1), and available preoperative and final follow-up AP and lateral upright radiographs. Radiographic parameters including major and minor Cobb angles, curve type, LIV tilt/translation, L4 tilt, and coronal balance were measured. CD was defined as the distance between C7PL and CSVL > 2 cm. Multiple logistic regression model was used to identify significant predictors of CD.

RESULTS

Out of 136 patients undergoing VBT, 94 patients (86 female and 6 male) met the inclusion criteria. The mean age at surgery was 12.1 (9-16) and mean follow-up period was 3.4 years (2-5 years). Major and minor curves, AVR, coronal balance, LIV translation, LIV tilt, L4 tilt were significantly improved after surgery. CD occurred in 11% at final follow-up. Lenke 1A-R (24%) and 1C (26%) had greater incidence of CD compared to 1A-L (4%), 2 (0%), and 3 (0%). LIV selection was not associated with CD. Multivariate logistic regression analysis yielded 1A-R and 1C curves as a predictor of CD with the odds ratio being 17.0.

CONCLUSION

CD occurred in 11% of our thoracic VBT patients. Lenke 1A-R and 1C curve types were predictors for CD in patients treated with VBT. There were no other preoperative predictors associated with CD.

The impact of spinal fusion of adolescent idiopathic scoliosis in Salah (Islamic Prayer) movement: a retrospective case-control study

BACKGROUND

Corrective spine surgery is widely accepted for treating severe adolescent idiopathic scoliosis (AIS). Postoperative spinal range of motion (ROM) could be affected after such surgery. In certain populations, such as Muslims, this ROM change can impact daily life, as it may affect the five-times-a-day prayer (Salah). This study aims to assess the influence of spinal fusion (SF) in Adolescent Idiopathic Scoliosis (AIS) during the daily Islamic prayer (Salah).

METHODS

SF-AIS patients were videoed while performing Salah prayer. The kinematic documentation was assessed and compared to Salah movements of a control group of age-matched Muslim AIS patients, who had not had surgery. The prayer quality changes were subjectively classified into improved, no change/remained, and worsened, according to the Global Perceived Effect (GPE). Functional outcome and pain were assessed by the Scoliosis Research Society Questionnaire Version 30 (SRS-30).

RESULTS

Thirty-nine women and five men (mean age±SD: 14.8±2.3 years) met the inclusion criteria, and unoperated AIS patients were used as control (twenty-two women, mean age±SD: 15.32±1.43 years). The prostrations ROM of the SF-AIS group differed significantly from the control group (p<0.05). The GPE of the prayer movement showed improvement in 36.4%, no change in 59.1%, and worsening in 4.5% of the SF-AIS patients. The worsened group had a significantly lower bowing ROM and higher prostrations ROM compared to all groups of prayer quality changes (p<0.05). SRS-30 scores showed good outcomes (function 4.0±0.2, pain 4.2±0.5), along with the overall bowing ROM and prostrations ROM (84.2±12.0° and 53.4±9.6°, respectively). Moreover, a significant moderate positive correlation between the bowing ROM and pain (r=0.417, p=0.007) was also found.

CONCLUSION

Spinal fusion positively affects AIS Islamic patients in maintaining their daily Salah movement, ROM and prayer quality. Prayer quality assessment should be given extra attention as an adjuvant of the SRS-30 questionnaire to evaluate Muslim patients.

Revision of Surgery for Adolescent Idiopathic Scoliosis: Reasons, Treatments, and Clinical Management with Case Examples

Adolescent idiopathic scoliosis (AIS) is a curvature of the spine that develops in children ages 10-18 and can be attributed to unknown causes. The Lenke AIS classification system provides a template to classify these deformities by curve type paired with recommended operative treatments. Treatment of this patient population has been associated with low complication rates and overall surgical success. Nonetheless, a fraction of patients remain susceptible to revision surgery. This manuscript will focus on the aspects of AIS surgery, highlighting case examples, the different treatment approaches, complication rates, and primary reasons for revision surgery and associated outcomes.

Preoperative factors associated with optimal outcomes of selective thoracic fusion at 5 years

PURPOSE

Prior work identified optimal outcomes at 2 years following selective thoracic fusion (STF) for adolescent idiopathic scoliosis (AIS) but it is unclear whether these published predictors represent what is required to achieve an optimal outcome with further time and potential growth. The purpose of this study was to determine the preoperative factors associated with optimal outcome of STF for AIS at 5 years.

METHODS

Patients with primary thoracic AIS (Lenke 1-4C curves) who underwent a STF and had minimum 5 years of follow-up were included. Optimal postoperative outcomes for a STF included a deformity-flexibility quotient (DFQ) < 4, lumbar curve < 26°, lumbar correction > 37%, C7-CSVL < 2 cm, lumbar prominence < 5°, and trunk shift < 1.5 cm. These outcomes were used to determine whether adhering to published recommendations for STF increased the likelihood of obtaining an optimal outcome at 5 years, which included: preoperative lumbar curve < 45°, lumbar bend < 25°, apical vertebral translation ratio > 1.2, and thoracic/thoracolumbar Cobb ratio > 1.2.

RESULTS

127 patients met inclusion. A preoperative lumbar curve < 45° was associated with an increased likelihood of achieving three of the optimal outcomes: DFQ < 4, lumbar curve < 26°, and lumbar prominence < 5°. Following the 25° bend rule resulted in two optimal outcomes, while Cobb ratio > 1.2 was only associated with one optimal outcome. AVT > 1.2 was not significantly associated with any optimal outcome measures.

CONCLUSION

This study found that at 5 years, performing a STF when there is a preoperative lumbar Cobb < 45° remained the best guideline for increasing the likelihood of an optimal outcome.

The Importance of Lumbar Curve Flexibility and Apical Vertebral Rotation for the Prediction of Spontaneous Lumbar Curve Correction in Selective Thoracic Fusion for Lenke Type 1 and 2 C Curves: Retrospective Cohort Study with a Mean Follow-Up of More than 10 years

STUDY DESIGN

Retrospective analysis of a prospectively collected data.

OBJECTIVE

Lumbar flexibility(LF) is generally defined with preoperative side bending films;it is not clear what percentage of LF predicts the spontaneous lumbar curve correction (SLCC) at long term follow up. Aim of this study was to find out cut-off value of preoperative LF,apical vertebra rotation(AVR) and apical vertebral translation(AVT);which may predict more than 50%SLCC.

METHODS

Patients with Lenke 1C&2C curves,treated with posterior STF,with a minimum 10 years follow up were included.The patients who had more than 50% SLCC(Group A) or less than 50% (Group B) were compared in terms of LF,AVR and AVT to understand a cut-off value of those parameters.Statistically, Receiver Operating Characteristic(ROC) test was used.

RESULTS

Fifty five AIS patients (54F, 1M) with mean age 14 (11-17) were included to study.Thoracic curve correction rate was 75%;lumbar curve correction rate was 59% at the latest follow up.Group A included 45(82%) patients at the latest follow up.Three patients (5%) showed coronal decompensation at early postop and 2 of them became compensated at f/up.ROC analyses showed 69% flexibility as the cut-off value for SLCC (P < .01).The difference between groups in terms of preop mean AVRs was significant (P = .029) (Group A = 1.9; Group B = 2.4).

CONCLUSION

In Lenke 1C&2C curves,whenever LF on the preoperative bending x-ray is greater than 70% (P < .01)and AVR is equal or less than grade 2,STF provides satisfactory clinical and radiological SLCC with more than mean 10 years f/up.This flexibility rate and apical vertebral rotation can be helpful in decision making for successful STF.

Defining risk factors for adding-on in Lenke 1 and 2 AR curves

PURPOSE

To identify curve/correction characteristics associated with adding-on at 2 years after posterior spinal fusion (PSF) in Lenke 1/2 AR curves.

METHODS

A prospective multicenter registry was queried to identify patients with adolescent idiopathic scoliosis (AIS), Lenke 1/2 AR curves, who underwent PSF with a minimum of 2-year follow-up. Patient characteristics as well as pre- and post- operative radiographic variables were evaluated using Classification and Regression Tree (CART) analysis to determine which factors contribute to adding-on.

RESULTS

253 patients treated with PSF were assessed for adding-on, of which 50 met our adding-on criteria. Univariate analysis revealed adding-on was associated several factors including: post-operative thoracic and lumbar curve magnitude (p > 0.001), first erect (FE) end instrumented vertebra (EIV) angulation (p = 0.009) and EIV translation (p = 0.001), younger age (p = 0.027), Risser stage (p = 0.024), and a more proximal lowest instrumented vertebra (LIV) (p < 0.001). Multivariate CART analysis showed the chance of adding-on was more than 2 times greater (42 vs 16%) when the chosen LIV was translated more than 2.7 cm from the CSVL. When the LIV was within 2.7 cm, the post-op risk of adding-on was increased when the LIV was not perfectly leveled (> 0.5°).

CONCLUSION

In Lenke 1 and 2 AR curves, pre-operative LIV translation appears to be an independent risk factor for adding-on; and in those with < 2.7 cm of LIV translation, FE LIV angulation also seems to increase the risk of adding-on. These factors are relevant in determining appropriate LIV selection and aid in identifying patients at risk for developing adding-on.

Selective Fusion in Lenke 1 B/C: Before or After Menarche?

STUDY DESIGN

A retrospective, comparative study.

OBJECTIVE

To determine the radiological behavior of the lumbar curve in selective fusions in premenarchal girls with adolescent idiopathic scoliosis (Lenke 1 B/C).

METHODS

A retrospective, comparative study was conducted. Selective fusion was performed in 21 patients younger than 18 years. The patients were divided into 2 groups: group A, after menarche (n = 12) and group B, before menarche (n = 9). Angles (preoperative, and at 1 and 2 years postoperatively) of the fused thoracic curves and the corresponding lumbar curves were measured and compared. For statistical analysis, the t test was used with a significance level of P < .05.

RESULTS

Mean preoperative angle value of the proximal/main thoracic curve was 61° in group A and 57° in group B (P = .44), and 21° and 20°, respectively, in the first year postoperatively (P = .61). Mean preoperative angle value of the lumbar curve was 43° in group A and 42° in group B (P = .87), while at 1 year after surgery, this curve was 19° in both groups (P = 0.91), and at 2 years postoperatively, the curve was 16° in group A and 17° in group B (P = .75).

CONCLUSIONS

Over a 2-year follow-up, we did not find significant radiological differences in lumbar curves between patients who underwent surgery before and after menarche.

Evaluation of long term outcome of selective fusion in patients with idiopathic scoliosis

BACKGROUND

Instrumented fusion is the standard treatment in adolescent idiopathic scoliosis (AIS). In patients with both thoracic and lumbar curves there is a trend toward fusing the major curve and keeping the spine mobile with greater function in the future. To evaluate the results of selective fusion in patients with AIS, we aimed to do this research in eligible patients with adolescent idiopathic scoliosis referred to educational hospitals in Isfahan, Iran.

METHODS

This is a retrospective cross-sectional study which was performed in 2019 in educational hospitals in Isfahan. The study population consisted of 21 patients with idiopathic scoliosis who had been treated with the selective fusion method in 2010-2018. Demographic data of patients including age, sex, and previous medical history and operation results were noted from medical documents of all patients. Cobb's angle measurements and assessments related to complications, Patients' satisfaction and outcome of the surgery were assessed using Patient Outcome Questionnaires developed by Scoliosis Research Society (SRS-22) and 36-Item Short Form Survey (SF-36) questionnaires.

RESULTS

A total of 21 patients with idiopathic scoliosis were enrolled in the study. The lowest follow-up duration was 2 years and the longest duration was 10 years. We showed that the mean upper curve before interventions were 50.66±7.55 and the mean lower curve before interventions was 35.19±3.86. These amounts improved significantly after surgeries (P<0.001). Evaluation of thoracic apical vertebral translation (AVT) to thoracolumbar or lumbar AVT ratio also showed significant improvements (P<0.001).

CONCLUSION

Patients undergoing selective fusion benefit from this surgical procedure. The upper and lower curves improved significantly and 85.8% of patients were satisfied with the surgery. Stopping fusion above the L2 in all patients left the lumbar spine mobile which is an important factor in patient satisfaction. We suggest that selective fusion be considered for surgical treatment of some patients with idiopathic scoliosis.

Severe persistent coronal imbalance following instrumented posterior spinal fusion for adolescent idiopathic scoliosis

STUDY DESIGN

Retrospective case-control study.

OBJECTIVE

The aim of this study was to identify the risk factors and health-related quality of life (HRQoL) impact of severe (> 4 cm) post-operative coronal imbalance at 2 years following posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS). Coronal imbalance is an unfavorable outcome following PSF for AIS, though the degree of imbalance in such patients is typically mild. We hypothesize that a small number of patients become and remain severely imbalanced post-operatively, though this phenomenon has not been well studied.

METHODS

Prospectively collected data from a large multicenter registry were reviewed. Patients with severe coronal imbalance (SCIB; > 4 cm) 2 years after PSF were included. Matched controls without SCIB at 2 years were included at a 3:1 ratio. Comparisons were made between demographics, pre-operative radiographic measures, surgical factors, residual post-operative radiographic measures, and 2-year SRS-22 scores.

RESULTS

Nine of 954 (0.9%) patients (88.9% females; mean age 14.8 ± 2.3 years) were found to be severely imbalanced at 2 years. These patients had significantly greater pre-operative bending thoracic curve magnitude (45° vs. 33°; p = 0.013), curve flexibility (22.9% vs. 63.3%; p = 0.004), and kyphosis (41° vs. 26.5°; p = 0.034) compared to matched controls. Pre-operative curve flexibility of < 20% was associated with a 23.8 times greater odds of SCIB (95% CI 2.1-250; p = 0.008). With respect to HRQoL, median SRS-22 pain (4.1 vs. 4.8; p = 0.041), self-image (3.9 vs. 4.6; p = 0.013), general function (4.5 vs. 5; p = 0.022), and total (4.1 vs. 4.7; p = 0.012) scores at 2 years were significantly lower in cases compared to controls.

CONCLUSIONS

In the present study, thoracic curve stiffness was a strong risk factor for severe post-operative coronal imbalance, which was associated with poor HRQoL measures. Increased pre-operative thoracic curve stiffness (< 20% flexibility) should raise surgeon awareness for altering surgical approach to minimize the risk of severe post-operative coronal imbalance.

LEVEL OF EVIDENCE

Level III.

Selective Thoracic Fusion for King-Moe Type II/Lenke 1C Curve in Adolescent Idiopathic Scoliosis: A Comprehensive Review of Major Concerns

INTRODUCTION

Controversies still exist in the surgical indications and outcomes of selective thoracic fusion (STF) for a primary thoracic curve with a compensatory large lumbar curve (King-Moe type II/Lenke 1C curve) in adolescent idiopathic scoliosis (AIS). Issues of the greatest concern regarding this curve type include curve criteria that indicate STF to prevent postoperative coronal decompensation and postoperative radiographic outcomes, including curve correction, coronal balance, and thoracolumbar kyphosis, after STF.

METHODS

This review comprehensively documents the issues raised in the literature regarding surgical indications and radiographic outcomes of STF for King-Moe type II/Lenke 1C curve in AIS.

RESULTS

Studies suggest that radiographic curve criteria indicating STF for this curve type include the preoperative dominance of the thoracic curve to the lumbar curve in the Cobb angle and the characteristics of the lumbar curve in magnitude and flexibility. Studies warn the need for a careful clinical evaluation of the thoracic and lumbar rotational prominences. Documented radiographic outcomes of importance include the postoperative behavior of the unfused lumbar curve, coronal or sagittal decompensation after STF, and factors associated with these issues. A comprehensive review of the literature suggests that the use of a segmental pedicle screw construct and better instrumented thoracic curve correction achieve better spontaneous lumbar curve correction. Although the causes of postoperative coronal decompensation remain multifactorial, preoperative coronal decompensation to the left and an inappropriate selection of the lowest instrumented vertebra are consistently reported to be the major causative factors.

CONCLUSIONS

STF has been validated in general for the treatment of King-Moe type II or Lenke 1C curve in AIS; however, controversies remain regarding the surgical indications and outcomes. Long-term impacts of residual lumbar curve, coronal decompensation, and mild thoracolumbar kyphosis on clinical outcomes after STF, along with optimal indications and strategy for STF, should further be assessed.

Does Symmetric Thoracic Fusion Make a Difference in Lenke 1 A/B AIS Patients?

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to compare the long-term outcomes of correction surgery for Lenke 1 A/B scoliosis among those with symmetric fusion (SF), upper-dominant fusion (UF), and lower-dominant fusion (LF) in adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Symmetric fusion, defined as equal number of vertebral levels included in instrumented fusion above and below the apical vertebra or disc of the primary curve, was a new concept raised in AIS selective fusion. Previous study showed that similar correction the effect on clinical outcomes of this fusion style.

METHODS

Preoperative, postoperative, and last follow-up radiographs of 117 consecutive patients with Lenke type 1A/B curves who underwent posterior selective thoracic instrumentation surgery were analyzed. Patients were divided into two groups (SF and nonsymmetric fusion [NSF]). Patients in NSF was further divided into two groups UF (more vertebrate was fused above the apex) and LF (more vertebrate was fused below the apex). Clinical outcomes and coronal decompensation including adding-on and trunk shift were analyzed and compared among three groups.

RESULTS

There was no significant difference between SF and NSF in magnitude of preoperative main thoracic curve (P = 0.69) and correction rate (P = 0.50). Distal adding-on was observed in 21 patients (17.9%), and coronal decompensation was observed in eight patients (6.8%) in all at final follow up. No significant differences were found between the two groups regarding adding-on phenomenon (P = 0.64) and coronal imbalance (P = 0.72). Significantly higher rates of adding-on were found in UF compared with SF and LF (P < 0.001). In a subgroup analysis between UF and LF in NSF patients, significant differences were found between two subgroups in the rate of trunk shift (P = 0.038). No significant differences in SRS-22 scores were observed among the three groups.

CONCLUSION

In Lenke 1A/B AIS with posterior selective fusion, SF provides no significant differences from NSF. However, in NSF, UF was found to be high risky of adding-on phenomenon.

LEVEL OF EVIDENCE

3.

Postoperative Lumbar Curve Progression Deteriorates Shoulder Imbalance in Patients with Lenke Type 2B/C Adolescent Idiopathic Scoliosis Who Underwent Selective Thoracic Fusion

OBJECTIVE

To evaluate the association between postoperative lumbar curve progression and the shoulder height in patients with Lenke type 2B/C adolescent idiopathic scoliosis (AIS).

METHODS

A total of 25 patients with Lenke type 2B/C AIS underwent posterior correction surgery in our institution from 2005-2014 were included. Standing x-ray films of the whole spine obtained before surgery, immediately after surgery, and at the last follow-up were analyzed with respect to the following parameters: proximal thoracic Cobb angle, main thoracic (MT) Cobb angle, lumbar Cobb angle, lumbar apical vertebral translation, distance between C7 plumb line and the central sacral vertical line, and radiographic shoulder height (RSH). Correlations between the change of RSH and the changes of other parameters were analyzed both immediately after surgery and at the last follow-up.

RESULTS

The change of RSH was significantly negatively correlated with both the change of MT Cobb angle (P < 0.05) and that of lumbar Cobb angle (P < 0.05) immediately after surgery, whereas the interval-time change of RSH was significantly positively correlated with the interval-time change of lumbar Cobb angle (P < 0.05) and that of lumbar apical vertebral translation (P < 0.05) at the last follow-up. The change of MT Cobb angle was an independent predictor for the change of RSH immediately after surgery, whereas the interval-time change of lumbar Cobb angle was an independent predictor for the interval-time change of RSH at the last follow-up.

CONCLUSIONS

Postoperative lumbar curve progression is a risk factor for deterioration of shoulder imbalance in patients with Lenke 2B/C AIS during the follow-up period.

Coronal Imbalance after Selective Posterior Thoracic Fusion in Patients with Lenke 1 and 2 Adolescent Idiopathic Scoliosis

Coronal decompensation is a common complication in Lenke 1 or 2 AIS patients after selective thoracic fusion (STF). However, the majority who developed immediately postoperative coronal decompensation experienced improvement and the related factors are not fully understood. The aim of this retrospective study was to investigate the prevalence of coronal imbalance in patients with Lenke 1 or 2 AIS and to explore radiological factors associated with spontaneous correction of coronal balance after surgery. Lenke 1 or 2 AIS patients receiving STF in our center from January 2013 to March 2015 were analyzed. Anteroposterior and lateral films were evaluated before surgery, at 1 month's and 2 years' follow-up. Patients were divided into 2 groups according to whether coronal imbalance occurred in the early postoperative period (1 month). Various radiological parameters as well as Scoliosis Research Society-22 were statistically compared between groups. Coronal decompensation was observed in 33 patients preoperatively, in 48 patients immediately postoperatively, and in 2 patients at final follow-up. Lowermost instrumented vertebra (LIV) disc angle (0.9° vs. 6.7°, p=0.019) and LIV- C7 plumb line and central sacral vertical line (CSVL) (-3.4mm vs. -13.7mm, p=0.020) increased in the final follow-up in the imbalanced group of type A modifier. The magnitude of lumbar curve was greater in the imbalanced group of type B or C modifier in the early postoperative period (19.5° vs. 12.6°, p=0.006; 25.5° vs. 13.7°, p<0.01), and this difference disappeared in the final follow-up. No differences in SRS-22 outcome scores were noted between groups in different time. Coronal imbalance was frequently detected immediately after STF in Lenke 1 or 2 AIS patients, with type C modifier slightly higher than A or B. Distal adding-on may help compensate for coronal imbalance in patients with type A modifier, while spontaneous correction of lumbar curve attributes to the improvement of coronal imbalance in patients with type B or C modifier.

Prevalence, Risk Factors, and Characteristics of the "Adding-On" Phenomenon in Idiopathic Scoliosis After Correction Surgery: A Systematic Review and Meta-Analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

To discuss the prevalence, risk factors, and characteristics of the "adding-on" phenomenon in idiopathic scoliosis (IS).

SUMMARY OF BACKGROUND DATA

There are controversies on the prevalence and risk factors of the "adding-on" phenomenon. In addition, there is no comprehensive study to describe the characteristics of "adding-on" in IS patients.

METHODS

We performed a systematic online search using PubMed, EMBASE, Web of Science, the Cochrane Library, and China WeiPu Library to identify eligible studies. Effect size (ES), odds ratios (OR), and weight mean difference (WMD) with 95% confidence interval (CI) were used to evaluate the incidence, characteristics, and risk factors for "adding-on," respectively.

RESULTS

The overall pooled prevalence of "adding-on" was 14%. Subgroup analysis showed that the prevalence of "adding-on" in Lenke 1A adolescent idiopathic scoliosis (AIS), Lenke 2 AIS, Lenke 5 AIS, and mixed AIS was 15%, 12%, 9%, and 16%, respectively. AIS patients with the "adding-on" phenomenon had smaller proximal thoracic curve (PTC), main thoracic curve (MTC), clavicle angle, T1 tilt angle and radiographic shoulder height (RSH), and larger correction of PTC. Age, Risser sign, preoperative PTC, preoperative MTC, preoperative lumbar curve (LC), preoperative coronal balance and sagittal balance, and T4 tile were identified as risk factors of "adding-on." Selection of lower instrumented vertebra (LIV) was also an important risk factor as LIV-Center Sacral Vertical Line (CSVL), LIV-end vertebra, LIV-Stable Vertebra, and LIV-Neutral vertebra, and deviation of LIV+1 was found to be significantly associated with "adding-on." Besides, postoperative MTC was also significantly different between patients with and without "adding-on."

CONCLUSION

The pooled prevalence varied differently in different types of IS. Patients with "adding-on" had smaller PTC, MTC, angle, T1 tilt angle and RSH, and larger correction of PTC. Younger age, less skeletal maturity, smaller preoperative PTC, smaller preoperative MTC, smaller preoperative LC, larger preoperative coronal, sagittal imbalance, selection of LIV, and overcorrection of coronal and sagittal alignment were risk factors for "adding-on."

LEVEL OF EVIDENCE

4.

Prognostic Role of Rib Hump in Overlying Thoracic Curve Correction Above Selective Fusion for Lenke 5 Idiopathic Adolescent Scoliosis

STUDY DESIGN

Prospective study.

OBJECTIVE

To assess whether rib hump is a prognostic factor of final thoracic Cobb angle.

SUMMARY OF BACKGROUND DATA

Correction of thoracolumbar/lumbar curve, preoperative thoracic curves angle, thoracic curves angle on bending, the thoracolumbar-lumbar angle/thoracic curves angle ratio, thoracic kyphosis, and growth stage influences spontaneous correction of uninstrumented thoracic curves angle above selective fusion for Lenke 5 Adolescent Idiopathic Scoliosis. Indeed, preoperative rib hump has never been expressly evaluated as a prognostic factor of final thoracic curves angle.

METHODS

In total, 50 patients with Lenke 5 Adolescent Idiopathic Scoliosis, selectively instrumented with posterior construct were included. Two patients were lost to follow-up and 48 had follow-up ≥2 years. Demographic data, preoperative thoracic rib hump (measured in millimeter in trunk anteflexion), and radiologic spinal parameters were recorded preoperatively and at last consultation. T test was used to compare mean values, linear and logistic regressions to assess predictability of final thoracic curve angle.

RESULTS

Main thoracolumbar-lumbar curve angle decreased from 47 degrees (range, 36-72 degrees) to 12 degrees at the final consultation (range, 1-28 degrees). Thoracic curves angle decreased from 26 degrees (range, 2-40 degrees) preoperatively to 16 degrees (range, 2-41 degrees) at the final consultation (P=0.001) (correction=37%). Preoperative rib hump was present in 10 patients. Final thoracic Cobb angle was 27 degrees (8-41 degrees) in patients with rib hump and 14 degrees (0-32 degrees) in patients without rib hump (P<0.001).Multiregression highlighted thoracic curves angle on bending (P=0.001), preoperative thoracic curves angle (P=0.011) and rib hump (P=0.012) as prognostic factors of higher final thoracic curves angle.

CONCLUSION

Rib hump significantly influenced final thoracic curves angle.

LEVEL OF EVIDENCE

Level III-prospective study.

Short Segment Spinal Instrumentation in Early-onset Scoliosis Patients Treated With Magnetically Controlled Growing Rods: Surgical Technique and Mid - Short-term Outcomes

STUDY DESIGN

A prospective, a single-institution, nonrandomized study.

OBJECTIVE

The aim of this study was to evaluate the safety and effectivity of short-segment instrumentation in early-onset scoliosis (EOS) patients treated by magnetic-controlled growing rods (MCGRs).

SUMMARY OF BACKGROUND DATA

Despite the common use of conventional growing rods and the recent popularity of MCGR in the treatment of progressive EOS, distal instrumented vertebra and number of the spanned levels are not standardized.

METHODS

Patients with progressive EOS, characterized by the major thoracic curve and nonstructural compensatory curve, were a candidate to be treated by dual MCGR short segment spinal instrumentation spanning the major thoracic curve; such patients are followed up for a minimum period of 30 months. Radiological data were collected and analyzed in terms of Cobb angle of both primary and secondary curve, kyphosis angle, T1-T12, and T1-S1 distances, and T1-T12/T1-S1 ratio in preoperative, postoperative, and last follow-up.

RESULTS

Sixteen patients with different diagnoses of EOS, mean age at the operation was 7 years and 10 months (5 years and 6 months-9 years and 10 months), and mean period of follow-up was 37 (30-54) months. The Cobb angle of both major and compensatory curve are corrected by the mean value of 62° (44-85), 35° (22-45) preoperatively to 29° (12-49), 14° (9-24) postoperatively, and maintained at 28° (10-47), 10° (2-20) in the last follow-up, respectively. The T1-T12/T1-S1 ratio was 0.58 preoperatively, 0.6 postoperatively, and 0.62 at the last follow-up. The average yearly T1-T12 and T1-S1 length increase were calculated as 7 and 9 mm/year, respectively.

CONCLUSION

Selective fusion principals are applicable to EOS, in that short segment instrumentation with MGCR in thoracic curve EOS patients is an effective technique in correction of both structural and compensatory curve, and in maintaining the correction during subsequent nonsurgical spinal distraction.

LEVEL OF EVIDENCE

4.

Distal Adding-on and Risk Factors in Severe and Rigid Scoliosis

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to identify associated risk factors of distal adding-on in severe and rigid scoliosis.

SUMMARY OF BACKGROUND DATA

Previous work has evaluated the challenges in the treatment of patients with severe and rigid scoliosis and the risks of complications. Furthermore, although several studies have investigated postoperative distal adding-on and attendant risk factors in Lenke type 1A scoliosis, very few have focused on distal adding-on in severe and rigid scoliosis.

METHODS

In this study, 48 consecutive patients with severe and rigid scoliosis underwent posterior spinal fusion surgery. The parameters of preoperative, immediately postoperative, and minimum 2-year follow-up radiographs were evaluated. The patients were classified as positive or negative for distal adding-on at follow-up, and risk factors were comparatively analyzed in the two groups.

RESULTS

The average Cobb angle and flexibility of the main thoracic curve (MTC) were 107.4° ± 15.9° and 16.4% ± 10.2%, respectively, before surgery. Distal adding-on was observed in 12 patients (25.0%) at follow-up. Univariate analysis identified several factors significantly associated with distal adding-on. Furthermore, significant independent risk factors identified by stepwise logistic regression analysis included the correction rate of the MTC immediately after surgery (odds ratio: 1.107, 95% confidence interval: 1.024-1.197, P = 0.011) and the difference between the lower instrumented vertebra (LIV) and last touching vertebra (LTV) levels (odds ratio: 0.121, 95% confidence interval: 0.028-0.518, P = 0.004).

CONCLUSION

In severe and rigid scoliosis, a high correction rate of the MTC immediately after surgery and the LIV level above the LTV were significantly associated with distal adding-on.

LEVEL OF EVIDENCE

3.