Selective Thoracic Fusion Research Articles

Flatback Revisited: Reciprocal Loss of Lumbar Lordosis Following Selective Thoracic Fusion in the Setting of Adolescent Idiopathic Scoliosis

Study DesignRetrospective review of prospective multicenter adolescent idiopathic scoliosis (AIS) database. ObjectiveTo investigate the relationship between iatrogenic loss of thoracic kyphosis (TK) after selective thoracic posterior spinal instrumentation and fusion (PSIF) for AIS with straightening of lumbar lordosis (LL). Summary of Background DataSegmental PSIF has become the standard of care for surgical treatment of severe AIS. Studies show that adults with flattening of TK and LL can develop pain and dysfunction associated with flatback syndrome. Analysis of post-fusion sagittal alignment is lacking in the AIS population. MethodsQuery of prospective multicenter database for AIS patients with Lenke 1, 2, or 3 curves who underwent selective thoracic PSIF (lowest instrumented vertebra equal or cephalad to L1) identified 123 patients with a minimum of 2 years' follow-up. Thoracic kyphosis (T5–T12), LL (T12–S1), and global sagittal alignment were measured preoperatively and at 2 years postoperatively. Health-related quality of life measures were examined. ResultsA total of 31% of patients had loss of TK and 42% lost LL. Patients with decreased TK had significantly higher rates of decreased LL (68%) than patients without decreased TK (31%). Multivariate regression confirmed that TK had significant predictive effect on LL (p < .001). Specifically, change in TK of 2° was associated with roughly 3° change in LL. There were no significant associations between changes in TK or LL and health-related quality of life. ConclusionsLoss of TK occurs commonly in selective fusion for AIS. This loss of kyphosis is strongly associated with reciprocal loss of LL. Spinal fusion can have unintended effects on sagittal alignment; these effects may have consequences that remain to be fully elucidated.

Selective Thoracic Fusion of Lenke I and II Curves Affects Sagittal Profiles But Not Sagittal or Spinopelvic Alignment: A Case-Control Study.

Literature review and retrospective case-control study (level 3 evidence) examining 50 adolescent idiopathic scoliosis (AIS) (Lenke I or II curve) cases with 32 healthy controls of the same age. The sagittal profiles were measured preoperatively, 6 months, and 2 years after surgery and compared with those of age-matched controls at baseline. The purpose of this study is to compare baseline sagittal profiles of AIS Lenke I and II curves with age-matched healthy controls and at 6 months and 2 years after surgery, as well as with previously published reports. Sagittal alignment and profiles have gained significant attention in spinal deformity outcomes. The sagittal profile of patients with AIS has been previously reported, as well as the effects of surgical correction, with inconsistent results and no clear references to nonscoliotic controls. Baseline sagittal profiles of 50 patients presenting with Lenke I or II AIS curves treated with selective thoracic fusion were compared with 32 age-matched controls without spinal pathology. These values were also measured at 6 months and 2 years postoperatively to examine effects of selective thoracic fusion over time. Sagittal parameters examined include pelvic incidence, pelvic tilt, C7 plumb line (sagittal vertical alignment), thoracic kyphosis, and lumbar lordosis. A literature review was performed comparing previously published data. Data are presented as mean (95% confidence interval). P value of less than 0.05 was considered significant. Interobserver reliability (Cohen κ= 0.49-0.95). All demographic and preoperative sagittal alignment parameters were comparable between controls and patients with AIS prior to surgery. After selective thoracic fusion, thoracic kyphosis decreased significantly from baseline (25.4º [21.6-29.2] vs. 15.3º [12.8-17.8]; P < 0.001) at 6 months and at 2 years (10.3º [7.5-13.1]; P < 0.001). The lumbar lordosis significantly decreased at 6 months from baseline (54.5º [28.6-80.5] vs. 61.8º (33.4-90.1); P < 0.001) and at 2 years (55.4º [29.0-81.9]; P < 0.001). Sagittal vertical alignment, pelvic tilt, and pelvic incidence were comparable between controls and patients with AIS at baseline and did not change with surgery. Adolescents with Lenke I or II curves have comparable sagittal profiles with those of healthy controls of the same age. This suggests that Lenke I and II curves may not be hypokyphotic as previously thought. After selective thoracic fusion, patients with AIS have a significantly decreased thoracic kyphosis, which is accompanied by reciprocal changes in the noninstrumented lumbar curve. Sagittal vertical alignment and pelvic tilt are not significantly affected. These results agree with previous reports, which suggest that constructs with pedicle screws have a higher impact on sagittal curves but do not affect sagittal or spinopelvic alignment. The long-term effects of abnormal sagittal profiles need further clarification. 3.

Disc and Vertebral Responses in the Unfused Lumbar Curve to Selective Thoracic Fusion in Lenke 1B/1C Scoliosis

Introduction Several previous studies have reported spontaneous lumbar curve correction for both anterior and posterior selective fusion in patients with Lenke 1B or 1C; however, the mechanism for this phenomenon remains unclear. The objective of this study is to analyze the detailed response of compensatory lumbar curve to selective thoracic fusion in patients with adolescent idiopathic scoliosis (AIS) with Lenke 1B/1C curve. Patients and Methods This study included patients with AIS with Lenke type 1B or 1C curves treated with posterior selective thoracic fusion (LIV at L1) from 2006 to 2008 in our institution. They had a major right thoracic curve and a compensatory lumbar curve. They were followed for at least 24 months. Radiographic measurements including disc angle and vertebra tilt in the lumbar region were compared before surgery, after surgery, and at latest follow-up. Results A total of 20 patients (7 boys and 13 girls) with a mean age of 15 years were included in this study. The thoracic curve was corrected from 46 ± 7.2 degrees preoperatively to 8 ± 4.7 degrees postoperatively, and to 9 ± 5.1 degrees at the latest follow-up. The mean lumbar compensatory Cobb angle was 36 ± 6.9 degrees before surgery, spontaneously correcting to 12 ± 5.3 degrees at latest follow-up. The most significant change of vertebral tilt occurred at LIV and the L4 vertebra in the coronal plane. Change in disc angle was 6.4 ± 3.1 degrees at L1/L2, 3.2 ± 2.3 degrees at L2/L3, 1.0 ± 1.3degrees at L3/L4, −2.3 ± 1.9 degrees at L4/L5, and −0.7 ± 0.5degrees at L5/S1. L1/L2 disc ranks highest among all the discs in the contribution to correction of the lumbar curve. Conclusion LIV and the L4 vertebra have a trend to be horizontal after selective thoracic fusion. Spontaneous correction of the unfused lumbar curve relies on the compensatory changes of lumbar disc angle, which are mainly at the junctional disc right below LIV. This study suggests that the disc right below LIV assumes the greatest portion of correction force transmitting therefore is prone to degenerate earlier than normal.

Selective Fusion in Adolescent Idiopathic Scoliosis with Curves Types 1B and 1C of the Lenke Classification

Introduction Despite the advances in the surgical treatment of the EIA, the goals remain the same: stop the progression of the curve, correct the deformity, preserve coronal and sagittal balance, minimize surgical complications (adjacent kyphosis, adding adjacent segments, coronal, and sagittal imbalance); but mainly “preserve moving segments.” Currently, there is a common agreement to perform a selective fusion for curves Lenke 1 B; being not equal for curves Lenke 1 C. The objective of this work is the retrospective evaluation of clinical and radiographic results of the selective fusion in the AIS Lenke 1 curves, with B and C modifiers. Material and Methods From May 2007 until December 2010, a total of 25 patients with AIS Lenke 1 type with modifiers B and C were operated on by using selective thoracic fusion. All cases were operated in the Unit of spinal surgery of the Provincial Hospital of the Centenary. The average age at the time of surgery was 14.6 years. Overall, 23 were women and 2 were men (11.5:1). They were taken for this study, clinical and radiographic preoperative evaluations, also in the immediate postoperative period, and at the end of follow-up. The follow-up took place at the POP immediately, 2 months later, and at the first year. The degree of maturation was obtained by the Risser method, which was 3.7 preoperative (average of 2–4). Among the total number of selected patients, 12 had a lumbar modifier B and 13 had a lumbar modifier C. Results Thoracic postoperative Cobb 25.1, percentage of correction 59.51; lumbar postoperative Cobb 11.6, percentage of correction 72.38; thoracic Cobb at the follow-up 30.1, lumbar Cobb at the follow-up 12.4; plummet CSVL (global coronal balance) preoperative average 14 mm plummet CSVL (global coronal balance) immediate POP 9 mm plummet CSVL (global coronal balance) POP follow-up 10.3 mm, AVT thoracic preoperative 57 mm AVT thoracic postoperative immediate 22 mm, AVT thoracic postoperative to the follow-up 24 mm, AVT lumbar preoperative 45 mm, AVT lumbar postoperative immediate 19 mm, AVT lumbar postoperative to the follow-up 20 mm, sagittal thoracolumbar balance preoperative 6 mm (−16 to 15 mm), sagittal thoracolumbar balance postoperative 6 mm (−14 to 15 mm). Conclusion In spite of the fact that the majority of the articles in the literature belong to a grade IV of evidence, and not a few times the information is contradictory; the selective fusion of the thoracic spine in patients with AIS and Lenke pattern 1 with B and C modifiers, is a safe and effective technique to achieve an adequate correction of the deformity, preserving a greater amount of mobile lumbar segments. It is important to apply the criteria that are present in the current literature in a personalized way, adapting them to the characteristics and needs of each patient in particular, to optimize the results of this procedure. The strict control and full examination pre- and postsurgical of the patients that will be submitted to a selective instrumentation, must be accurate, to perform a correct indication and obtain the best clinical outcomes.

Postoperative behavior of thoracolumbar/lumbar curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C adolescent idiopathic scoliosis

Background Controversy still exists around surgical strategies for Lenke type 1C and 2C curves with primary thoracic and compensatory lumbar curves in adolescent idiopathic scoliosis (AIS). The benefit of selective thoracic fusion (STF) for these curve types is spontaneous lumbar curve correction while saving more mobile lumbar segments. However, a risk of postoperative coronal decompensation after STF has also been reported. This multicenter retrospective study was conducted to evaluate postoperative behavior of thoracolumbar/lumbar (TLL) curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C AIS.

Optimal radiographical criteria after selective thoracic fusion for patients with adolescent idiopathic scoliosis with a C lumbar modifier: does adherence to current guidelines predict success?

Retrospective review of prospective data. To define optimal postoperative coronal parameters after selective thoracic fusions (STFs) and to test these parameters against recommended criteria for when to perform an STF. Previous studies have provided recommendations for when STF should be performed; however, clear parameters for target outcomes are lacking. Patients with Lenke 1C to 4C curves with adolescent idiopathic scoliosis from a multicenter database who underwent STF with minimum 2 years of follow-up were included. Postoperative parameters included lumbar Cobb angle, trunk shift, coronal balance, percent lumbar correction, and deformity-flexibility quotient. First, the upper 95% confidence interval for each parameter was calculated (queried data threshold) and set as the limit of "optimal" outcomes. Second, an independent surgeon survey was performed, and in patients with unanimous surgeon agreement of "success," the upper 95% confidence interval was determined (surgeon-derived threshold). Scoliosis Research Society-22 scores were compared between those above and below these 2 thresholds. Then, these outcomes were used to determine whether adherence to, or disregard for, previously published guidelines for STF were predictive of final outcome. A total of 106 patients were analyzed. Target postoperative parameters as determined by the queried data and surgeon-derived thresholds were similar and rounded to: deformity-flexibility quotient less than 4, lumbar Cobb angle less than 26°, lumbar correction more than 37%, coronal balance 2 cm or less, and trunk shift less than 1.5 cm. Patients within target parameters had significantly better Scoliosis Research Society-22 satisfaction scores. Neither preoperative apical vertebral translation ratio more than 1.2 nor Cobb angle ratio more than 1.2 predicted 2-year success. Preoperative lumbar curve less than 45° and lumbar bend less than 25° were associated with increased likelihood of optimal outcomes. Optimal postoperative outcomes for STF should include a lumbar Cobb angle less than 26°, coronal balance 2 cm or less, deformity-flexibility quotient less than 4, lumbar correction more than 37%, and trunk shift less than 1.5 cm. These findings suggest that performing an STF in patients with a preoperative lumbar Cobb angle less than 45° or a preoperative lumbar bend less than 25° will increase one's chances of success. 4.

Postoperative behavior of thoracolumbar/lumbar curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C adolescent idiopathic scoliosis.

Controversy still exists around surgical strategies for Lenke type 1C and 2C curves with primary thoracic and compensatory lumbar curves in adolescent idiopathic scoliosis (AIS). The benefit of selective thoracic fusion (STF) for these curve types is spontaneous lumbar curve correction while saving more mobile lumbar segments. However, a risk of postoperative coronal decompensation after STF has also been reported. This multicenter retrospective study was conducted to evaluate postoperative behavior of thoracolumbar/lumbar (TLL) curve and coronal balance after posterior thoracic fusion for Lenke 1C and 2C AIS. Twenty-four Lenke 1C and 2C AIS patients who underwent posterior thoracic fusion were included. The mean age of patients was 15.7 years old at time of surgery. Constructs used for surgery in all cases were pedicle screw constructs ending at L3 or above. Radiographic measurements were performed on Cobb angles of the main thoracic and TLL curves and coronal balance. Factors related to final Cobb angle of TLL curve and postoperative change of coronal balance were investigated. Mean Cobb angles for main thoracic and TLL curves were 59.0° and 43.9° preoperatively, and were corrected to 21.5° and 22.0° at final follow-up, respectively. Mean coronal balance was -5.6 mm preoperatively and was corrected to -14.6 mm at final follow-up. Final Cobb angle of TLL curve was significantly correlated with immediate postoperative Cobb angle of main thoracic curve and tilt of lowest instrumented vertebra (LIV). Postoperative change of coronal balance was significantly correlated with selection of LIV relative to stable vertebra. Spontaneous correction of TLL curve occurred consistently by correcting the main thoracic curve and making the LIV more horizontal after posterior thoracic fusion for Lenke 1C and 2C AIS. The more distal fixation to stable vertebra resulted in coronal balance shifting more to the left postoperatively.

Could structural and noncompensatory Lenke 3 and 4C lumbar curves be nonstructural and compensatory? Lenke 1, 2, 3, and 4 curve types were similar and could be considered collectively as a single indication for selective thoracic fusion.

Retrospective radiographical review. To demonstrate that the structural and noncompensatory Lenke 3 and 4C lumbar curves could be nonstructural and compensatory. Historically, Lenke 3 and 4C curves were not recommended for selective thoracic fusion (STF) because the lumbar curve was considered structural and noncompensatory. However, consecutive series of Lenke 3 and 4C curves suggest successful treatment with STF. Between 2001 and 2004, 2005 and 2008, and 2010 and 2012, 3 consecutive series of 108, 134, and 78 surgically treated Lenke 1, 2, 3, and 4C curves were reviewed, respectively. The coronal curve criteria for the curves treated with STF during each period were lumbar side bending Cobb angle less than 25° and meeting the Lenke ratio criteria, lumbar side bending Cobb angle 35° or less, and lumbar side bending Cobb angle 45° or less, respectively. The sagittal curve criteria for STF during each period was absence of junctional thoracolumbar kyphosis 20° or more between T10 and L2. The technique used for STF was the Guan-Din method. Radiographs of all the curves treated with STF were analyzed before and after surgery. Optimal instrumented thoracic and compensatory lumbar correction was obtained for all Lenke 1, 2, 3, and 4C curves treated with STF in each period. As the coronal criteria for STF were broadened, the extent of feasibility of STF was expanded and the rate of STF increased. Although Cobb angle, apical vertebral translation, and apical vertebral rotation magnitudes of Lenke 3 and 4C curves were larger and more severe than those of Lenke 1 and 2C curves, optimal compensatory correction could still be obtained for Lenke 3 and 4C curves. The structural and noncompensatory Lenke 3 and 4C lumbar curves were proven to be nonstructural and compensatory. Lenke 1, 2, 3, and 4C curves have similar natures and similar responses to the same technique (Guan-Din method) used for STF and could be considered collectively as a single indication for STF. The extent of feasibility of STF could be expanded from Lenke 1 and 2 curves to Lenke 1, 2, 3, and 4 curves. 2.

Association of Postoperative Shoulder Balance With Adding-on in Lenke Type II Adolescent Idiopathic Scoliosis

A retrospective, multicenter study. To investigate the relationship between postoperative shoulder balance and adding-on in Lenke type 2 adolescent idiopathic scoliosis. Postoperative shoulder imbalance (PSI) and adding-on are the main postoperative complications occurring at the proximal to upper instrumented vertebra and the distal to the lower instrumental vertebra (LIV), respectively. Inadequate selection of LIV in the selective thoracic fusion surgery may result in postoperative distal adding-on. It remains unclear whether postoperative shoulder balance is associated with postoperative adding-on. Preoperative, postoperative, and 2-year follow-up radiographs of 142 consecutive patients with Lenke type 2 curves who underwent posterior-fusion surgery were analyzed. The patients were grouped into PSI positive and negative at follow-up. Radiographical and categorical factors between patients with and without PSI were compared. The relationship between the radiographical shoulder height and the parameters of adding-on were analyzed. PSI occurred in 23 patients (16.2%) and distal adding-on was recognized in 20 patients (14.1%) at final follow-up. The occurrence of adding-on was significantly lower in the shoulder imbalance group at follow-up (P < 0.01). There was no shoulder imbalance occurring in the patients with distal adding-on at final follow-up (P < 0.01). Correlation analysis showed that the radiographical shoulder height was positively correlated with the change in the angulation of the first disc below LIV (r = 0.228, P ≤ 0.01) and negatively correlated with the deviation change of the LIV+1 at follow-up (r = -0.254, P ≤ 0.01). The postoperative shoulder balance and postoperative distal adding-on were weakly but significantly associated with each other, and both shoulder imbalance and adding-on need to be prevented in Lenke type 2 curves.

Selective thoracic fusion in AIS curves: the definition of target outcomes improves the prediction of spontaneous lumbar curve correction (SLCC)

The decision of when to use selective thoracic fusion (STF) and the prediction of spontaneous lumbar curve correction (SLCC) remain difficult. Using a novel methodological approach, the authors yielded for a better prediction of SLCC and analyzed the efficacy of anterior scoliosis correction and fusion (ASF). A retrospective analysis of 273 patients treated with ASF for STF was performed. In total, 87 % of the patients showed a Lenke 1 curve pattern. The lumbar curve modifier was classified as A in 66 % of the patients, B in 21 % of the patients and C in 13 % of the patients. The fusion length averaged 6.7 levels. The analysis included an assessment of radiographic deformity and correction, surgery characteristics, complications and revisions and clinical outcomes to improve the prediction of SLCC. Patients with a Type A-L, Type B or Type C modifier were stratified into a target follow-up lumbar curve (LC) category of ≤20° or >20°. Linear regression analyses were performed to assess the accuracy of predicting LC magnitude, and a multivariate logistic regression model was built using the following preoperative (preop) predictors: main thoracic curve (MTC), LC, MTC-bending and LC-bending. The output variable indicated whether a patient had an LC >20° at follow-up. A variable selection algorithm was applied to identify significant predictors. Two thresholds (cut-offs) were applied to the test sample to create high positive and negative prediction values. The data from 33 additional patients were gathered prospectively to create an independent test sample to learn how the model performed with independent data as a test of the generalizability of the model. The average patient age was 17 years, and the average follow-up period was 33 months. The MTC was 53.1° ± 10.2° preoperatively, 29.8° ± 10.5° with bending and was 25.4° ± 9.7° at follow-up (p < 0.01). The LC was 35.7° ± 7.5° preoperatively, 8.9° ± 5.8° with bending, and 21.8° ± 7.0° at follow-up (p < 0.01). After applying a variable selection algorithm, the preop LC [p < 0.02, odds ratio (OR) = 1.09] and preop LC-bending (p < 0.009, OR = 1.14) remained in the model as significant predictors. The performance of the linear regression model was tested in an independent test sample, and the difference between the observed and predicted values was only 1° ± 4.5°. Based on the test sample, the lower threshold was set to 25 %, and the upper threshold was set to 75 %. Patients with prediction values of 25-75 % were identified by the model, but by definition of the model, no prediction was made. In the test sample, 87 % of the patients were correctly classified as having an LC ≤20° at follow-up, and 84 % of the patients were correctly classified as having an LC >20°. The model test in the independent test sample revealed that 100 % of the patients were correctly classified as having an LC ≤20°, and 86 % of the patients were correctly classified as having an LC >20°. After analyzing a sufficiently large sample of 273 patients who underwent ASF for STF, significant predictors for SLCC were established and reported according to the surgical outcomes. Application of the prediction models can aid surgeons in the decision-making process regarding when to perform STF. Our results indicate that with stratification of outcomes into target curves (e.g., an LC <20°), future benchmarks for STF might be more conclusive.

Is there a role for the 5-degree rule in adolescent idiopathic scoliosis?

Nonstructural curves are defined in the Lenke classification system for adolescent idiopathic scoliosis as bending out to <25 degrees. A caveat in the original paper states, however, that if the difference in Cobb magnitude between the major and minor curves is <5 degrees, then the minor curve should be considered structural, regardless of its Cobb magnitude. It is unclear whether following this rule affects patient outcomes. A multicenter retrospective study using a prospectively collected database was performed on surgical adolescent idiopathic scoliosis patients, with 2 years of minimum follow-up. All the lumbar curves measured <25 degrees on bending x-ray. Curves (major and minor) that were within <5 degrees of each other were analyzed in 2 treatment subsets: nonselective fusion (NS) and selective thoracic fusion (STF1), and compared with similar selective fusion cases with false double major curves with a lumbar curve between 5 and 10 degrees less in magnitude than the thoracic curve magnitude (STF2). Preoperative and 2-year postoperative radiographic and SRS-22 parameters were compared. Of 58 patients, there were 14 NS, 11 STF1, and 33 STF2. NS had larger preoperative curves than STF1, but achieved better lumbar correction (58%) than STF1 (32%) or STF2 (41%) (P=0.004). STF1 tended to have more preoperative coronal imbalance than STF2 (-2.26 vs. -1.12 cm) (P=0.066) but were similar at 2 years. Preoperative thoracic rib prominence measures were similar for all groups, but NS had significantly worse rib prominence than STF1 (NS: 8.4 vs. STF1: 4.4, P=0.046) at 2 years. There were no differences among the 3 groups in SRS-22 scores preoperatively and at 2 years. Almost half of the cases with curves within <5 degrees of each other did not follow the 5-degree rule, suggesting that there is variability among surgeons in their definition of what is truly structural. Selective thoracic fusion cases behaved similarly regardless of whether or not the curves were within 5 degrees of each other. The results of our analysis of the 5-degree caveat challenge its utility as a criterion for defining structural curves. Level II.

Guan-Din Method

Retrospective radiographical review. To evaluate the outcome of selective thoracic fusion (STF) by using the Guan-Din method for the treatment of major thoracic compensatory lumbar (MTCL) curves. Performing STF for MTCL curves is to minimize the loss of lumbar motion and the risk of lumbar degeneration or pain. Surgical treatment of MTCL curves aims to maximize the rate of STF for MTCL curves while optimizing instrumental thoracic and compensatory lumbar correction. The Guan-Din method has been demonstrated to be able to enhance the lumbar curve's capacity for spontaneous correction and broaden the current curve criteria of MTCL curves for STF. Between 2004 and 2010, 510 consecutive surgically treated MTCL curves were reviewed. Of these MTCL curves, who met the criteria of lumbar side bending Cobb 35° or less and without global thoracic hyperkyphosis and/or thoracolumbar kyphosis (T10-L2 ≤20°), were treated with STF using the Guan-Din method. Radiographs were analyzed before surgery, immediately after surgery, and at the most recent follow-up (range, 2-8 yr). Curve types of 510 MTCL curves according to Lenke system were as follows: 1A (n = 91), 2A (n = 74), 3A (n = 6), 4A (n = 2), 1B (n = 93), 2B (n = 34), 3B (n = 8), 4B (n = 5), 1C (n = 84), 2C (n = 26), 3C (n = 72), and 4C (n = 15). Of the 510 MTCL curves, 458 (90%) curves were treated with STF. A mean 73% thoracic correction and 63% lumbar correction was obtained at the most recent follow-up. Of the 197 surgically treated MTCL curves with a lumbar C modifier, 148 (75%) curves that contained 57 Lenke 1C and 2C curves and 40 Lenke 3C and 4C curves that did not meet Lenke curve criteria for STF, were successfully treated with STF. A mean 67% thoracic correction and 57% lumbar correction was obtained at the most recent follow-up. The rate of STF and the magnitude of correction of MTCL curves in this study were significantly greater than those in all other reports. No significant change in global coronal and sagittal imbalance was observed. The rate of STF and the compensatory correction of MTCL curves could be maximized by using the Guan-Din method as the method for STF. 4.

Selection of Lower Instrumented Vertebra in Treating Lenke Type 2A Adolescent Idiopathic Scoliosis

A retrospective, observational, and multicenter study. To identify the ideal lower instrumented vertebra (LIV) to prevent distal adding-on after surgical correction of Lenke type 2A curve. LIV level may affect the risk of postsurgical adding-on. The choice of the last touching vertebra (LTV)-the most caudal vertebra of the main thoracic curve that touches the central sacral vertical line when standing-as an appropriate LIV has been validated for Lenke type 1A but not type 2A curve. Radiographs obtained before, immediately after, and 2 years after surgery were evaluated for 116 consecutive patients who underwent posterior thoracic fusion surgery for Lenke type 2A curve. The LIV was proximal to the LTV in 18 patients (PLTV), distal in 43 (DLTV), and at the LTV in 55 (ALTV). Significant independent factors associated with adding-on were analyzed first by univariate analysis, and then by stepwise logistic regression analysis. Distal adding-on was present in 16 patients (13.8%) at follow-up: 9 PLTV (50.0%), 3 DLTV (7.0%), and 4 ALTV (7.3%). Adding-on was significantly more common in the PLTV group. One PLTV-group patient required revision surgery to treat adding-on. Univariate analysis identified the following significant factors associated with adding-on: the T2-T5 kyphosis angle and shoulder height before, immediately after, and 2 years after surgery; the lumbar Cobb angle at the 2-year follow-up; the 2-year postoperative lumbar curve correction rate; and the difference between the LIV and the end vertebra, neutral vertebra, and LTV levels. Significant independent risk factors identified by stepwise logistic regression analysis included the clavicle angle at follow-up, the correction rate of the lumbar curve immediately after surgery, and the difference between the LIV and LTV levels. A LIV at or distal to the LTV may prevent postoperative adding-on in Lenke type 2A curve. 3.

Prognosis of spontaneous thoracic curve correction after the selective anterior fusion of thoracolumbar/lumbar (Lenke 5C) curves in idiopathic scoliosis

Background contextPrognosis of minor lumbar curve correction after selective thoracic fusion in idiopathic scoliosis is well defined. However, the prognosis of minor thoracic curve after isolated anterior fusion of the major lumbar curve has not been well described. PurposeTo define the prognosis of spontaneous thoracic curve correction after selective anterior fusion of the lumbar/thoracolumbar curve in idiopathic scoliosis. Study designA retrospective cohort study on the prognosis of the minor curve after selective anterior correction and fusion of the lumbar/thoracolumbar curve in idiopathic scoliosis. Patient sampleIdiopathic lumbar scoliosis patients treated with anterior spinal fusion. Outcome measuresThe Scoliosis Research Society 22 questionnaire was used as an outcome measure at the final follow-up. MethodsTwenty-eight patients were included in this study. Four patients were male, 24 patients were female, and average age at the time of surgery was 16 years. Mean follow-up was 48 months. According to the Lenke Classification, 22 patients were 5CN, 5 were 5C−, and 1 was 5C+. All operations were performed in the same institution. Standing long posterior-anterior and lateral radiographs were taken just before surgery, 1 week after surgery, and at final follow-up. ResultsThe mean preoperative Cobb angle of the lumbar (major) curve was 53° (standard deviation [SD]=8.6) and that of the thoracic (minor) curve was 38.4° (SD=6.24). The lumbar and thoracic curves were corrected to 10° (SD=7.6) and 25° (SD=8.3) postoperatively and measured 17° (SD=10.6) and 27° (SD=7.7), respectively, at the last follow-up. There was a significant difference between the preoperative and postoperative measurements of the minor curves (p<.05). However, there was no significant difference between the early postoperative and the final follow-up measurements (p>.05). Regarding the overall sagittal balance, there was no significant difference between preoperative, early, and late postoperative measurements (p>.05). ConclusionsSelective anterior fusion of the major thoracolumbar/lumbar curve was an effective method for the treatment of Lenke Type 5C curves. Minor thoracic curves did not progress after selective fusion of thoracolumbar/lumbar curves in minimum 2-year follow-up.

Return to sports after surgery to correct adolescent idiopathic scoliosis: a survey of the Spinal Deformity Study Group

Background contextThere are no guidelines for when surgeons should allow patients to return to sports and athletic activities after spinal fusion for adolescent idiopathic scoliosis (AIS). Current recommendations are based on anecdotal reports and a survey performed more than a decade ago in the era of first/second-generation posterior implants. PurposeTo identify current recommendations for return to sports and athletic activities after surgery for AIS. Study design/settingQuestionnaire-based survey. Patient sampleAdolescent idiopathic scoliosis after corrective surgery. Outcome measuresType and time to return to sports. MethodsA survey was administered to members of the Spinal Deformity Study Group. The survey consisted of surgeon demographic information, six clinical case scenarios, three different construct types (hooks, pedicle screws, hybrid), and questions regarding the influence of lowest instrumented vertebra (LIV) and postoperative physical therapy. ResultsTwenty-three surgeons completed the survey, and respondents were all experienced expert deformity surgeons. Pedicle screw instrumentation allows earlier return to noncontact and contact sports, with most patients allowed to return to running by 3 months, both noncontact and contact sports by 6 months, and collision sports by 12 months postoperatively. For all construct types, approximately 20% never allow return to collision sports, whereas all surgeons allow eventual return to contact and noncontact sports regardless of construct type. In addition to construct type, we found progressively distal LIV resulted in more surgeons never allowing return to collision sports, with 12% for selective thoracic fusion to T12/L1 versus 33% for posterior spinal fusion to L4. Most respondents also did not recommend formal postoperative physical therapy (78%). Of all surgeons surveyed, there was only one reported instrumentation failure/pullout without neurologic deficit after a patient went snowboarding 2 weeks postoperatively. ConclusionsModern posterior instrumentation allows surgeons to recommend earlier return to sports after fusion for AIS, with the majority allowing running by 3 months, noncontact and contact sports by 6 months, and collision sports by 12 months.

Sagittal Alignment Two Years After Selective and Nonselective Thoracic Fusion for Lenke 1C Adolescent Idiopathic Scoliosis

Sagittal balance is a major predictor of outcomes in adults with scoliosis, but this is rarely a problem in children with AIS. In patients with Lenke 1C AIS, the impact of sagittal curve parameters after selective thoracic fusion (STF) versus fusion of both curves (non-selective thoracic fusion, NSTF) has not been well studied. Sagittal balance appears to be adequately maintained following STF for up to 20 yrs postop. However, moderate kyphosis may not become clinically relevant until the patient loses the ability to compensate through pelvic retroversion.

Selective Thoracic Fusion in Lenke 1C Curves

Multicenter retrospective analysis of prospectively collected data. Evaluate radiographical and clinical characteristics of patients undergoing a selective thoracic fusion (STF) for Lenke 1C curves. STF of adolescent idiopathic scoliosis has been advocated for the so-called "false double major" curve (Lenke 1C/King type II). Despite these recommendations, many surgeons continue to perform nonselective fusions for this curve type. It is unknown to what extent other factors influence the surgeon's fusion-level selection. A prospective multicenter database included 264 patients with surgically treated Lenke 1C curves and were divided into 2 groups. The STF group included patients with the lowest instrumented vertebra at or cephalad to L1, whereas the nonselective fusion group included patients with the lowest instrumented vertebra at or caudal to L3. Preoperative radiographical, clinical (scoliometer), Scoliosis Appearance Questionnaire (SAQ), and Scoliosis Research Society (SRS) questionnaires were analyzed and compared. Only 138 of 264 patients (49%) underwent an STF. Sex ratio (90% vs. 86% female), average age (14.7 vs. 14.8 yr), and preoperative main thoracic Cobb angles (56.0° ± 9.9° vs. 55.3° ± 11.4°) were not significantly different (STF vs. nonselective fusion). However, the average thoracolumbar/lumbar (TL/L) preoperative Cobb angle was significantly smaller in the STF group (42.1° ± 8.6° vs. 47.0° ± 9.0°; P < 0.001), whereas the main thoracic: TL/L Cobb ratio (1.35 ± 0.20 vs. 1.18 ± 0.15; P < 0.001), apical vertebral translation, and rotation (1.82 ± 0.59 vs. 1.31 ± 0.53; P < 0.001), (1.16 vs. 0.98; P < 0.001) ratios were significantly greater in the STF group. Preoperative coronal balance, sagittal Cobb angles (including T10-L2 kyphosis) and Risser Grade were not significantly different. Preoperative TL/L scoliometer measures were significantly less in the STF group (8.1° ± 3.7° vs. 10.3° ± 5.4°; P = 0.001). On the SAQ, the STF group had less desire for an appearance change. Despite the recommendation to fuse only the structural thoracic curve in a 1C curve, only 49% of patients were treated with an STF. Those undergoing an STF had smaller TL/L Cobb angles, less TL/L clinical deformity, larger main thoracic: TL/L ratios, and less desire for an appearance change. 3.

Three-dimensional finite element simulation of surgical correction for Lenke 2 type adolescent idiopathic scoliosis

Objective To simulate different anterior and posterior correction strategies using finite element model of Lenke 2 type adolescent idiopathic scoliosis(AIS),in an effort to seek the optimal surgical protocol.Methods The finite element model of Lenke 2 type AIS was established and used to simulate five surgical strategies.The effectiveness and shoulder balance parameters were compared among different surgical approaches.Results The coronary proximal thoracic(PT) Cobb angle and corrective rates of the five surgical strategies were 21.5(44.8%),26.5(32.1%),28.1(27.9%),34.1(12.5%),and 32(17.9%).The corrective rates for the main thoracic curves were not significantly different among the five strategies,and the physiological sagittal configuration was maintained.Postoperative radiographic shoulder balance parameters were increased for all five surgical protocols.Except for strategy A(posterior fusion from T2 to T11),other four strategy achieved the following outcomes: coracoid height difference9 mm,clavical angle2.5° and clavicular tilt angle difference4.5°.Conclusion Simulation of posterior correction and fusion to T2 including both thoracic curve can achieve excellent three-dimensional corrective results and balanced shoulders for Lenke 2 type AIS model with preoperative left elevated shoulder.Partial fusion of PT curves to T3 or T4 results in inferior corrective rate of PT curve and mild or moderate shoulder imbalance.Simulation of anterior or posterior selective main thoracic curve fusion has very low spontaneous PT corrective rate and can lead to deteriorated shoulder imbalance slight to moderate degrees.

Is Decompensation Preoperatively a Risk in Lenke 1C Curves?

A review of a multicenter, prospective registry of patients surgically treated for adolescent idiopathic scoliosis. To investigate preoperative and postoperative distribution of coronal decompensation in Lenke 1C curves and to determine whether a selective thoracic fusion (STF) affects the results of coronal decompensation. Numerous causes of postoperative coronal decompensation in Lenke 1C curves have been reported; however, there are few reports focusing on preoperative decompensation and its relation to postoperative decompensation in Lenke 1C curves. Patients with Lenke 1C prospectively collected from a multicenter study were analyzed. Preoperatively, patients were grouped as decompensated (C7-CSVL > 2 cm) or balanced (C7-CSVL within 2 cm, where CSVL is central sacral vertical line). Preoperative distribution and factors for postoperative coronal decompensation were investigated. Seventy-one patients (53 STF, 18 nonselective fusions) were included. Preoperatively, coronal balance was skewed to the left (-17 ± 13 mm). Of the 21 STF decompensated to the left preoperatively, 12 (57%) remained to the left at 2 years. Postoperative thoracic correction was significantly better in those balanced postoperatively (57%) compared with those who remained decompensated (46%; P < 0.05). There were 32 STF patients who were balanced preoperatively, with 10 of these (31%) decompensated to the left at 2-year follow-up. This rate (31%) was significantly less than the group that was decompensated preoperatively (57%, P = 0.04). In the nonselective fusion group, 16 out of 18 patients (89%) were balanced at 2-year follow-up, independent of preoperative balance. Patients with Lenke 1C tended to be decompensated to the left preoperatively. In those decompensated preoperatively who underwent a STF, the majority remained greater than 2 cm to the left at 2-year follow-up. Patients with both thoracic and lumbar curves fused had better coronal balance at 2 years than selectively treated patients. Although not a contraindication to performing a selective fusion, treating surgeons should be prepared for modest coronal decompensation in 40% of patients with Lenke 1C treated with selective fusion of the thoracic curve alone. 3.

Distal Adding-on in Lenke 1A Scoliosis

A radiographical follow-up and analysis. To identify appropriate radiographical parameters for measuring the extent of distal adding-on and to discuss criteria for determining the onset of distal adding-on. There is no consensus on how to determine the onset of distal adding-on in Lenke 1A scoliosis. Such questions as: "Which radiographical parameters should be used for measuring the extent of distal adding-on?" and "What criteria should be applied in determining the onset of distal adding-on?" need to be answered. We reviewed all the AIS cases surgically treated in an institution from 2003 through 2009. Inclusion criteria were as follows: (1) patients with Lenke 1A curves who were treated with selective thoracic fusion; (2) age less than 30 years; (3) 2-year radiographical follow-up. Eight radiographical parameters were tested to see if they are potential instruments in the detection of distal adding-on. Fifty-three patients met the inclusion criteria. No pseudarthrosis or crankshaft phenomenon was observed in the current cohort. Five out of 8 radiographical parameters: thoracic Cobb, LIV-CSVL distance, LIV + 1-CSVL distance, thoracic AV-CSVL distance and LIV + 1 tilt angle, in the 2 years after surgery, showed significant increase. The remaining 3 parameters: LIV tilt angle, T1-CSVL distance and number of vertebrae within Cobb, however, did not show significant increase. In regard to the 5 parameters that have the potential to detect the onset of distal adding-on, we found a high correlation between every 2 of them. The correlation coefficients range from 0.504 to 0.962 (P = 0.001), suggesting that all of them are in a positive linear relationship. Regarding the criterion for determining the onset of distal adding-on, an increase of more than 10 mm in LIV-CSVL distance in the postoperative period can be considered as a the main criterion because it is unlikely to be induced by measurement errors. LIV-CSVL distance could be an ideal parameter for measuring the extent of distal adding-on. Distal adding-on can be determined when the LIV-CSVL distance increases by 10 mm in the postoperative period.