Predictability of the spontaneous lumbar curve correction after selective thoracic fusion in idiopathic scoliosis

3D analysis of the preoperative deformity in AIS can be used to guide surgical treatment decisions for selective thoracic fusion

PURPOSE

To identify 3D measures of scoliosis from preoperative imaging that are associated with optimal radiographic outcomes after selective thoracic fusion (STF) for adolescent idiopathic scoliosis (AIS).

METHODS

Subjects with primary thoracic curves (Lenke 1-4, B or C modifiers) fused selectively (L1 or above) who had preoperative 3D reconstructions and minimum 2 years of follow-up were included. An optimal outcome at 2 years was defined as having 4 of 5 parameters previously defined in the literature: (1) lumbar curve < 26º, (2) deformity flexibility quotient < 4, (3) C7-CSVL < 2 cm, (4) lumbar prominence < 5º and (5) trunk shift < 1.5 cm. Univariate and CART analyses were performed to identify preoperative variables associated with achieving an optimal outcome 2 years postoperatively.

RESULTS

Ninety-nine (88F, 11 M) patients met inclusion. Mean age was 15 ± 2 years. Fifty-one subjects (52%) had an optimal outcome. Seven preoperative deformity measures representing smaller thoracolumbar/lumbar deformity in the optimal group were found to be significant on univariate analysis. CART analysis identified the following variables associated with optimal outcomes: difference in apical rotation > 30° = 27% optimal outcomes, difference in apical rotation ≤ 30° and coronal vertebral wedging of lumbar apex > 3° = 46% optimal outcomes, and difference in apical rotation ≤ 30° and coronal vertebral wedging of lumbar apex ≤ 3° = 80% optimal outcomes (p < 0.05).

CONCLUSION

Optimal outcomes after STF were associated with a preoperative difference in apical vertebral rotation in the axial plane less than 30° between thoracic and lumbar curves as well as coronal plane vertebral wedging of the lumbar apical vertebra less than 3°.

Breaking the Rules in Three Dimensions: What to Expect After a Thoracic-only Fusion With Structural Thoracic and Thoracolumbar Curves

OBJECTIVE

Despite guidelines to fuse both thoracic and thoracolumbar/lumbar (TH/L) curves in patients with structural curves in both regions, a thoracic-only fusion allows preservation of lumbar motion segments. The purpose of this study was to assess the 2-year postoperative three-dimensional (3D) radiographic and clinical outcomes of patients with double or triple major (thoracic curves >TH/L curves) structural curves who underwent a thoracic-only fusion.

METHODS

A prospective adolescent idiopathic scoliosis registry was queried for double or triple major curves undergoing thoracic-only posterior fusion and a minimum 2-year follow-up. 3D reconstructions were generated from bi-planar radiographs. Paired sample t tests were used to assess differences in the coronal, sagittal, and axial planes pre and postoperatively, as well as Scoliosis Research Society Questionnaire-22 scores. Pearson correlations were utilized to identify variables related to spontaneous lumbar derotation.

RESULTS

Twenty-two patients met the inclusion criteria. Both thoracic [61 ± 10 degrees to 20 ± 9 degrees ( P < 0.001)] and lumbar curves [41 ± 7 degrees to 22±7 degrees ( P < 0.001)] had significant coronal improvement and T5 to T12 kyphosis improved from 7 ± 14 degrees to 23 ± 8 degrees ( P < 0.001). The thoracic apical translation was significantly improved postoperatively (4.7 ± 1.5 to 0.5 ± 1 cm, P < 0.001), but the lumbar apical translation was unchanged (-1.7 ± 0.6 to -1.7±0.8 cm, P = 0.94). Scoliosis Research Society Questionnaire-22 scores significantly improved by 2 years postoperative.

CONCLUSIONS

Unlike the 3D correction observed in nonstructural TH/L curves after thoracic-only fusion, patients with double or triple major curves demonstrated only spontaneous coronal correction of the lumbar curve, whereas the sagittal and axial planes were not significantly improved. These radiographic parameters did not negatively affect subjective or clinical outcomes at minimum 2-year follow-up.

LEVEL OF EVIDENCE

Level IV-therapeutic.

Optimal lowest instrumented vertebra selection with consideration of coronal and sagittal planes to prevent distal junctional complications in patients with Lenke type 1A and 2A adolescent idiopathic scoliosis

PURPOSE

Postoperative distal adding-on and distal junctional kyphosis are major distal junctional complications after selective thoracic fusion in patients with adolescent idiopathic scoliosis (AIS). This study aimed to investigate the incidence of distal adding-on and distal junctional kyphosis and evaluate the validity of our selection criteria for the lowest instrumented vertebra (LIV) in patients with Lenke type 1A and 2A AIS.

METHODS

We retrospectively analyzed the data of patients with Lenke type 1A and 2A AIS, who underwent posterior fusion surgery. LIV selection included the followings: (1) stable vertebra on traction film, (2) disc space neutralization below the LIV on the side-bending film, and (3) lordotic disc below the LIV on the lateral film. Radiographic parameters and the revised 22-item Scoliosis Research Society Questionnaire (SRS-22r) were evaluated. The incidence of postoperative distal adding-on and distal junctional kyphosis was also investigated.

RESULTS

Ninety patients (83 women and 7 men; 64 with type 1A and 26 with type 2A) were included. After the operation, each curve and the SRS-22r of self-image, mental health, and subtotal domains were significantly improved. Distal adding-on occurred in three patients (3.3%, one in type 1A and two in type 2A) at 2 years postoperatively. No patients exhibited distal junctional kyphosis.

CONCLUSIONS

Our LIV selection criteria could reduce the incidence of postoperative distal adding-on and distal junctional kyphosis in patients with Lenke type 1A and 2A AIS.

LEVEL OF EVIDENCE

Level IV.

Satisfactory immediate spontaneous correction may not mean satisfactory final results for moderate TL/L curves after selective thoracic fusion in AIS patients

BACKGROUND

Few studies have focused on the chronic spontaneous behavior of the unfused TL/L curve during follow-up. The purpose of the present study was to explore the behavior of the unfused TL/L curve during a long-term follow-up to identify the risk factors for correction loss.

METHODS

Sixty-four age-matched female AIS patients undergoing selective thoracic fusion were enrolled. Patients were divided into 2 groups according to whether there was correction loss. Risk factors for correction loss of the unfused TL/L curves were analyzed. The relationship and difference between the immediate postoperative thoracic and TL/L Cobb angles were explored.

RESULTS

The TL/L Cobb angle was 28.17° before surgery, 8.60° after surgery, and 10.74° at the final follow-up, with a correction loss of 2.14°. Each subgroup contained 32 cases. A smaller postoperative TL/L Cobb angle was the only risk factor that was independently associated with TL/L correction loss. In the LOSS group, there was a significant difference and no correlation between the immediate postoperative TL/L and the thoracic Cobb angle. In the NO-LOSS group, there was a moderate correlation and no difference between them.

CONCLUSION

A smaller immediate postoperative TL/L Cobb angle may have been associated with TL/L correction loss during the long-term follow-up. Thus, good immediate postoperative spontaneous correction may not mean a satisfactory outcome at the final follow-up after STF. Mismatch between thoracic and TL/L Cobb angles immediately after surgery may also be related to correction loss of the unfused TL/L curves. Close attention should be paid in case of deterioration.

Simultaneous Hypercorrection of Lowest Instrumented Vertebral Tilt and Main Thoracic Curve is Associated With Progression of Residual Lumbar Curve in Adolescent Idiopathic Scoliosis

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To determine radiographic parameters, including the lowest instrumented vertebral (LIV) tilt, related to the postoperative magnitude and progression of residual lumbar curves (LCs) in adolescent idiopathic scoliosis patients who underwent posterior spinal fusion with LIV at or above L1.

SUMMARY OF BACKGROUND DATA

Although several guidelines have been proposed for thoracic curve fusion, factors related to the postoperative magnitude and potential progression of unfused LCs remained undetermined. The effect of the LIV tilt on residual LCs is also unclear.

MATERIALS AND METHODS

Patients with Lenke type 1 to 4 curves who underwent posterior spinal fusion with LIV at or above L1 with a minimum follow-up period of 2 years were evaluated. Prediction models for residual LCs were developed using multivariate linear regressions with selected radiographic parameters. Subgroup analyses, followed by sensitivity tests, were then performed for variables best predicting the progression of residual LCs.

RESULTS

A total of 130 patients were included. Multivariate linear regression analysis showed that the immediate postoperative LIV-tilt angle was associated with the immediate postoperative LCs and the prediction model for residual LCs, with high accuracy ( R =0.93 and 0.77, respectively). Sensitivity tests revealed immediate postoperative LIV-tilt angle <10° and correction rate of main thoracic curve Cobb angle >53% as predictors for progression of residual LCs, and they reached moderate discrimination when combined together as one criterion (odds ratio=16.3, 95% confidence interval=5.3-50.1; sensitivity=89%, specificity=67%, positive predicted value=51%, negative predicted value=94%).

CONCLUSION

The current study revealed that LIV tilt, as an operable factor during surgery, is not only a determinant in prediction models showing high correlation with the magnitude of postoperative LCs but a predictor for progression of residual LCs. "Immediate postoperative LIV-tilt angle <10° and correction rate of main thoracic curve Cobb angle >53%," as a united criterion, could serve as a predictor for progression of residual LCs.

Spontaneous Lumbar Curve Correction Following Vertebral Body Tethering of Main Thoracic Curves

BACKGROUND

Growth modulation through anterior vertebral body tethering (AVBT) has emerged as a fusionless option for the treatment of progressive scoliosis. When tethering the main thoracic curve, the compensatory thoracolumbar/lumbar curve must correct indirectly as a result. The present study evaluated the response of these lumbar curves following AVBT of the main thoracic curves.

METHODS

Patients who underwent thoracic AVBT and who had a minimum follow-up of 2 years were included. Magnitudes of the thoracic and lumbar curves were recorded preoperatively and at the first-erect and 2-year postoperative visits. Lumbar curves were further stratified according to their lumbar modifier (A, B, or C). Analysis of variance (ANOVA) and repeated-measures ANOVA were performed to compare correction rates, and the Pearson coefficient was utilized to determine the correlation between the tethered thoracic curve and uninstrumented lumbar curve magnitudes.

RESULTS

A total of 218 patients were included. Thoracic curve correction was 40% at the first-erect visit and 43% at 2 years (p = 0.012). Lumbar correction was 30%, 26%, and 18% at the first-erect visit (p < 0.001 for all compared with preoperatively) and minimally changed at 31%, 26%, and 24% at 2 years for lumbar modifiers A, B, and C, respectively. A total of 118 patients (54%) showed thoracic curve improvement between the first-erect and 2-year visits. In a subgroup analysis, these patients had a correction in lumbar curve magnitude from preoperatively to the first-erect visit of 30%, 22%, and 16% for lumbar modifiers A, B, C, respectively, that increased to 42%, 34%, and 31% at 2 years, with strong correlation to thoracic correction at 2-year follow-up (r = 0.557, p < 0.001).

CONCLUSIONS

Although there was immediate lumbar correction following AVBT of a main thoracic curve, further improvement following initial correction was only observed among patients with growth modulation of the thoracic curve. Considering all patients, the uninstrumented lumbar curve corrected 30% at 2 years and the instrumented thoracic curve corrected 40%. As indications for AVBT are refined, these data will provide insight into the response of the uninstrumented lumbar curve.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Can We Stop Distally at LSTV-1 for Adolescent Idiopathic Scoliosis With Lenke 1A/2A Curves?

STUDY DESIGN

A retrospective study.

OBJECTIVE

To determine in which case one level proximal to last substantially touching vertebra (LSTV-1) could be a valid lowest instrumented vertebra (LIV), in which case distal fusion should extend to last substantially touching vertebra (LSTV), and to identify risk factors for distal adding-on.

SUMMARY OF BACKGROUND DATA

Posterior thoracic fusion to save more lumbar mobile segments has become the mainstay of operative treatment for adolescent idiopathic scoliosis (AIS) with Lenke 1A/2A curves. Although previous studies have recommended selecting the LSTV as LIV, good outcomes could still be achieved in some cases when LSTV-1 was selected as LIV.

METHODS

Ninety-four patients were included in the study with a minimum of 2-year follow-up after posterior thoracic instrumentation, in which LSTV-1 was selected as LIV. Patients were identified with distal adding-on between first erect radiographs and 2-year follow-up based on previously defined parameters. Factors associated with the incidence of adding-on were analyzed.

RESULTS

The mean follow-up duration was 37.7 ± 15.8 months. Forty patients (42.6%) with LSTV-1 selected as LIV achieved good outcomes at the last follow-up. Several preoperative risk factors significantly associated with distal adding-on were identified, including lower Risser (P = 0.001), longer thoracic curve length (P = 0.005), larger rotation and deviation of LSTV-1 (P  < 0.001), and preoperative coronal imbalance (P = 0.013).

CONCLUSION

Skeletally immature patients with long thoracic curve, preoperative coronal imbalance, large rotation, and deviation of LSTV-1 are at increased risk of distal adding-on when selecting LSTV-1 as LIV. Under this condition, distal fusion level should extend to LSTV; while in other case, LSTV-1 could be a valid LIV.Level of Evidence: 4.

Characteristics analysis of segmental and regional lumbar spontaneous compensation post thoracic fusion in Lenke 1 and 2 adolescent idiopathic scoliosis

OBJECTIVE

To explore the characteristics of compensation of unfused lumbar region post thoracic fusion in Lenke 1 and 2 adolescent idiopathic scoliosis.

BACKGROUND

Preserving lumbar mobility in the compensation is significant in controlling pain and maintaining its functions. The spontaneous correction of the distal unfused lumbar curve after STF has been widely reported, but previous study has not concentrated on the characteristics of compensation of unfused lumbar region post thoracic fusion.

METHOD

A total of 51 Lenke 1 and2 AIS patients were included, whose lowest instrumented vertebrae was L1 from January 2013 to December 2019. For further analysis, demographic data and coronal radiographic films were collected before surgery, at immediate erect postoperatively and final follow-up. The wedge angles of each unfused distal lumbar segments were measured, and the variations in each disc segment were calculated at the immediate postoperative review and final follow-up. Meanwhile, the unfused lumbar curve was divided into upper and lower parts, and we calculated their curve angles and compensations.

RESULTS

The current study enrolled 41 females (80.4%) and 10 males (19.6%). Thirty-six patients were Lenke type 1, while 15 patients were Lenke type 2. The average main thoracic Cobb angle and thoracolumbar/lumbar Cobb angle were 44.1 ± 7.7°and 24.1 ± 9.3°, preoperatively. At the final follow-up, the disc wedge angle variation of L1/2, L2/3, L3/4, L4/5 and L5/S1 was 3.84 ± 5.96°, 3.09 ± 4.54°, 2.30 ± 4.53°, - 0.12 ± 3.89° and - 1.36 ± 2.80°, respectively. The compensation of upper and lower coronal lumbar curves at final follow-up were 9.22 ± 10.39° and - 1.49 ± 5.14°, respectively.

CONCLUSION

When choosing L1 as the lowest instrumented vertebrae, the distal unfused lumbar segments' compensation showed a decreasing trend from the proximal end to the distal end. The adjacent L1/2 and L2/3 discs significantly contributed to this compensation.

Spinal balance and lumbar curve stability after selective thoracic fusion in idiopathic scoliosis

PURPOSE

Selective thoracic fusion (STF) for double curve patterns in idiopathic scoliosis is an attractive treatment option. However, short-term coronal decompensation and truncal imbalance are known findings. Previous studies with hook constructs showed that eventually balance is achieved via an increase in lumbar curve magnitude, as the lumbosacral obliquity did not change following surgery. Our aim is to investigate patients with idiopathic curves who underwent STF using all-pedicle screw constructs to determine if the uninstrumented lumbar curve and lumbosacral obliquity responded in the same manner as was previously reported with all-hook constructs.

METHODS

102 consecutive patients with Lenke 1B, 1C or 3C curves who underwent STF using all-screw constructs at a single institution were included in this study. Radiographic assessment was performed, and patient reported outcomes were obtained. Subgroup analyses were performed based on preoperative thoracic: lumbar curve ratio as well as lumbar curve magnitude.

RESULTS

Overall, the patients showed statistically significant improvement in both trunk shift and L4-pelvis obliquity at final follow-up. The uninstrumented lumbar curves trended toward improvement over time, but did not reach statistical significance (p = 0.107). SRS-30 scores were statistically significantly improved in multiple domains.

CONCLUSION

Selective thoracic fusion is an excellent treatment option in most double curve patterns. Balance in the coronal plane is predictably achieved at 2-year follow-up. The lumbosacral obliquity improves more with screw technology than was previously found with hook constructs; therefore, the improvement in balance over time does not depend upon an increase in the uninstrumented lumbar curve.

LEVEL OF EVIDENCE

IV.

Predictors of spontaneous lumbar curve correction in thoracic-only fusions: 3D analysis in AIS

PURPOSE

To evaluate how 3D parameters of the instrumented thoracic spine relate to the uninstrumented lumbar spine following thoracic-only fusion (TOF) for adolescent idiopathic scoliosis (AIS) and determine the factors predictive of lumbar correction.

METHODS

A multi-center retrospective review was conducted of AIS patients with Lenke 1-4 B or C curves undergoing fusion of their thoracic spine only with minimum 2-year follow-up and 3D spine reconstructions from biplanar radiography. Pre-operative to 2-year post-operative differences were evaluated. Pearson's correlations were used to identify 3D coronal, sagittal and axial relationships at 2 years post-operative. Multivariate linear regression was used to identify variables most predictive of lumbar curve correction.

RESULTS

Eighty-four AIS patients met inclusion (54 B modifiers, 30 C modifiers). Average pre-operative thoracic and lumbar curves were 54 ± 9° and 41 ± 7° and corrected to 19 ± 7° and 21 ± 7°, respectively. 3D T5-T12 thoracic kyphosis increased from 6 ± 13° to 26 ± 8°. Thoracic and lumbar apical rotation decreased from - 14 ± 6° to -5 ± 6° and 13 ± 5° to 11 ± 6°, respectively. Thoracic curve correction correlated with lumbar curve correction (r = 0.67, p = 0.001) and decreased LIV tilt correlated with smaller residual lumbar curve magnitude (r = 0.63, p < 0.001). Increasing 3D kyphosis of the instrumented segment correlated with increased percentage lumbar curve correction (r = 0.29, p = 0.009). Multivariate linear regression showed LIV tilt and thoracic curve magnitude as the most predictive variables of post-operative residual lumbar curve magnitude, and percent correction of the thoracic curve and change in 3D instrumented kyphosis as most predictive of percent correction of the lumbar curve.

CONCLUSIONS

Analysis of 3D data highlights several considerations for AIS patients undergoing TOF. Maximizing thoracic curve correction, leveling the LIV, and to a lesser extent, restoring kyphosis in the instrumented segment are the factors most likely to result in greater correction of the instrumented lumbar curve following thoracic-only fusions in Lenke 1-4 B and C curves.

Long-term Outcome of Selective Thoracic Fusion Using Rod Derotation and Direct Vertebral Rotation in the Treatment of Thoracic Adolescent Idiopathic Scoliosis: More Than 10-Year Follow-up Data

STUDY DESIGN

This was a retrospective comparative study.

OBJECTIVE

To evaluate long-term outcomes of selective thoracic fusion (STF) using both rod derotation (RD) and direct vertebral rotation (DVR) with pedicle screw instrumentation (PSI) in the treatment of thoracic adolescent idiopathic scoliosis (AIS) with a minimum 10-year follow-up.

SUMMARY OF BACKGROUND DATA

Postoperative compensation and maintenance of the unfused lumbar curve after STF is very important factor for the satisfactory results in the treatment of thoracic AIS.

PATIENTS AND METHODS

Sixty-five patients with thoracic AIS treated with STF from the neutral vertebra (NV) to NV or NV-1 with RD and DVR were retrospectively analyzed with a minimum 10-year follow-up. Patients were divided into 2 groups: satisfactory (n=52) and unsatisfactory groups (n=13). Unsatisfactory results were defined as an adding-on, a lowest instrumented vertebra (LIV) tilt of >10 degrees, or coronal balance >15 mm.

RESULTS

No significant differences were observed in the main thoracic curve between the satisfactory and unsatisfactory groups postoperatively (P=0.218) and at the last follow-up (P=0.636). Significant improvements of LIV tilt and disk angle were observed in both groups, but these improvements deteriorated during the follow-up period in the unsatisfactory group. Significant differences of apical vertebra (AV) and end vertebra (EV) were observed postoperatively (AV: P=0.001, EV: P=0.001) and at the last follow-up (AV: P<0.000, EV: P<0.000) between the 2 groups.

CONCLUSIONS

STF using RD and DVR can achieve satisfactory deformity correction for thoracic AIS with satisfactory compensatory lumbar curve that was maintained over long-term follow-up. Progression of unfused lumbar curve closely related with LIV tilt and disk angle showing insufficient DVR. Therefore, STF with sufficient DVR required to achieve satisfactory deformity correction and prevent a distal adding-on phenomenon in the treatment of thoracic AIS.

Distal Adding-On Phenomenon in Lenke IA and Lenke IIA: Risk Analysis and Selection of the Lowest Instrumented Vertebra

OBJECTIVE

To analyze the risks of the distal adding-on phenomenon and identify the ideal lowest instrumented vertebra (LIV) for Lenke IA and IIA.

METHODS

A total of 84 patients with Lenke IA or Lenke IIA treated with posterior all-pedicle-screw instrumentation were enrolled in this cohort study. Radiographs that were obtained before, immediately after, and 2 years after the operation were measured. Patients were grouped based on the occurrence of the adding-on phenomenon. Independent risk factors were evaluated between these 2 groups via univariate analysis and logistic regression analysis.

RESULTS

All patients obtained optimal correction of the main thoracic curve and lumbar curve after selective thoracic fusion. Eighteen patients among a total of 84 patients suffered from the distal adding-on phenomenon during the 2-year follow-up. Multivariable analysis revealed that the primary factors were preoperative thoracolumbar or lumbar curve size in supine side-bending films (odds ratio 0.75, P = 0.008), preoperative thoracic kyphosis (T5-T12) (odds ratio 0.743, P = 0.022), and the difference between the LIV and the LSTV (lowest substantial touched vertebra). All 7 (100%) patients whose LIVs were proximal to the LSTV suffered from distal adding-on phenomenon, whereas 7 of 40 (17.5%) suffered from distal adding-on phenomenon when the LIV was distal to the LSTV. Patients whose LIV was distal to the LSTV had the lowest incidence of the distal adding-on phenomenon (10.8%).

CONCLUSIONS

An LIV located proximal to the LSTV should be avoided during selective thoracic fusion for Lenke IA and IIA to prevent the distal adding-on phenomenon. For patients who have a small thoracolumbar or lumbar curve size in bending films or a small T5-T12 angle before surgery, the next vertebra distal to the LSTV may be an optimal choice.

Accurate prediction of spontaneous lumbar curve correction following posterior selective thoracic fusion in adolescent idiopathic scoliosis using logistic regression models and clinical rationale

INTRODUCTION

Accurate prediction of spontaneous lumbar curve correction (SLCC) after selective thoracic fusion (STF) remains difficult. This study sought to improve prediction accuracy of SLCC. The hypothesis was preoperative and intraoperative variables could predict SLCC < 20°.

METHODS

A multicenter observational prospective analysis was conducted to determine predictors of SLCC in AIS patients that had posterior STF. Curve types included major thoracic curves (Lenke 1, 3-4).The primary outcome variable was to establish prediction models, and a postoperative lumbar curve (LC) ≤ 20° was defined as the target variable. Multivariate logistic regression models were established to study the relationship between selected variables and a LC ≤ 20° versus a LC > 20° at ≥ 2-year follow-up. Single and dual thresholds models in perspective of clinical rationales were applied to find models with the highest positive/negative predictive values (PPV/NPV). The secondary outcome measure was SRS scores at ≥ 2-year follow-up.

RESULTS

410 patients were included. At ≥ 2-year follow-up 282 patients had LC ≤ 20°. These patients had better SRS-22 scores than those with LC > 20° (P = 0.02). The postoperative LC and LC ≤ 20° were predicted by preoperative LC and LC-bending Cobb angle (P < 0.01, r = 0.4-0.6). Logistic regression models could be established to identify patients at risk for failing the target LC ≤ 20°.For preoperative LC and LC-bending, the prediction model achieved a NPV/PPV of 80%/72%. If the postoperative main thoracic curve is combined with the preoperative LC and a gray area for difficult decisions was allowed, model accuracy could even be improved (NPV/PPV = 96%/81%).

CONCLUSION

An accurate prediction model for postoperative SLCC was established based on a large analysis of prospective STF cases. These models can support prediction and understanding of postoperative SLCC aiding in surgical decision making when contemplating a selective thoracic fusion. These slides can be retrieved under Electronic Supplementary Material.

Ten-Year Outcomes of Selective Fusions for Adolescent Idiopathic Scoliosis

BACKGROUND

Selective fusions of the structural curve remain a common treatment strategy for adolescent idiopathic scoliosis, yet long-term outcomes are not well-understood. The purpose of this study was to report 10-year prospective radiographic and patient-rated outcomes of selective fusions of the main thoracic (MT) or thoracolumbar/lumbar (TL/L) curve, with particular attention to the behavior of the uninstrumented, compensatory curve.

METHODS

A prospectively collected multicenter database was used to identify patients who had been followed regularly for least 10 years after a selective MT or TL/L fusion for adolescent idiopathic scoliosis. Interval radiographs were evaluated for coronal and sagittal Cobb angles as well as overall coronal balance. Scores on the Scoliosis Research Society Questionnaire (SRS-24) were catalogued and evaluated. Radiographic outcomes and SRS-24 scores were compared between preoperative and postoperative time points using repeated-measures analysis of variance. Individual patient records were screened for recent curve progression of >5°, and these cases were methodically evaluated.

RESULTS

Fifty-one patients with selective fusions (21 MT and 30 TL/L) for adolescent idiopathic scoliosis who had been followed for at least 10 years were identified. The instrumented MT and TL/L curves were corrected by an average of 51% and 60%, respectively, at 10 years. The uninstrumented, compensatory curves had gradual spontaneous correction that approached the magnitude of the fused curve at 5 years postoperatively, with the correction maintained at 10 years. This led to excellent coronal balance. A subgroup of patients had recent progression of the primary curve adjacent to the prior fusion or within the instrumented segments, resulting in a compensatory progression of the uninstrumented curve. On the whole, SRS scores did not decrease during follow-up, and no patient had secondary operations.

CONCLUSIONS

Selective fusion of a primary thoracic or lumbar curve in properly selected patients with adolescent idiopathic scoliosis will result in spontaneous correction of the uninstrumented curve and a durable result for at least 10 years.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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.

Prediction of Spontaneous Lumbar Curve Correction After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis Lenke Type 1 Curves

STUDY DESIGN

This is a retrospective single-center and single-surgeon study.

OBJECTIVE

The present study examined for preoperative parameters having the highest correlation with compensatory thoracolumbar/lumbar (TL/L) curve correction 2 years after surgery in adolescent idiopathic scoliosis (AIS) patients with Lenke type 1 curves.

SUMMARY OF BACKGROUND

Several parameters have been considered to evaluate the flexibility of compensatory TL/L curve in AIS patients with Lenke type 1 curves. However, the imaging position with the strongest correlation with postoperative spontaneous TL/L curve correction is unknown.

DATA

In total, 37 patients with AIS Lenke type 1 curves who had undergone skip pedicle screw fixation were followed for a 2-year period were enrolled.

MATERIALS AND METHODS

TL/L Cobb angles measured at the standing posteroanterior view, supine position, supine position with maximum bending, supine position with traction, prone position, and prone-push position were determined before surgery. Using TL/L Cobb angles determined 2 years postoperatively, correlations between preoperative and postoperative Cobb angles were calculated for each position using the Spearman rank-correlation coefficient, linear regression analysis, and paired t tests.

RESULTS

Mean preoperative mean±SD TL/L Cobb angle was significantly improved from 31±9 to 13±8 degrees at the study end point. In analyses of correlations between postoperative TL/L Cobb angle and preoperative parameters, the supine position with traction was most strongly associated with TL/L curve correction rate at 2 years after surgery (r=0.72; P<0.01), with paired t tests revealing a significant mean difference of 3.1 degrees.

CONCLUSIONS

Preoperative Cobb angle evaluated at the supine position with traction had the strongest correlation with spontaneously corrected TL/L curve Cobb angle after selective thoracic fusion for AIS Lenke type 1 curves. Accordingly, it may be sufficient to evaluate TL/L curve correction at this position only to reduce radiation exposure and operative time.

Relationships Between the Axial Derotation of the Lower Instrumented Vertebra and Uninstrumented Lumbar Curve Correction: Radiographic Outcome in Lenke 1 Adolescent Idiopathic Scoliosis With a Minimum 2-Year Follow-up

BACKGROUND

Preoperative spinal parameters are used to guide the fusion levels in adolescent idiopathic scoliosis (AIS) spinal surgery. However, the impact of the factors modifiable by the surgeon in varying levels of preoperative patient-specific variables is not fully explored. The goal of this study was to identify the association between axial rotation correction of the lower instrumented vertebra (LIV) and spontaneous correction of the uninstrumented lumbar spine as a function of preoperative 3 dimensional (3D) curve characteristics in Lenke 1 AIS.

METHODS

Twenty-three Lenke1 AIS with a minimum 2-year follow-up were included. All patients had biplanar spinal x-rays and 3D reconstructions at preoperative, first erect, and 2-year follow-up visits. Five patient factors were measured preoperatively: kyphosis and lumbar modifiers, and thoracic to lumbar curve rotation, translation, and frontal deformity angle ratios. One surgical factor, percentage of LIV rotation correction, was determined from the preoperative and first erect 3D models. A factorial design analysis was implemented to determine the impact of surgical and patient factors, both separately and in combination, on 2-year radiographic outcomes of spontaneous correction of the uninstrumented spine.

RESULTS

Spontaneous lumbar Cobb and lumbar apical rotation correction were predicted significantly by patient and surgical factors, P<0.05. Lumbar modifier, percentage correction of LIV rotation, the interaction between LIV rotation correction and lumbar modifier, and the interaction between LIV rotation correction and thoracic to lumbar apical vertebrae translation ratio correlated significantly to 2-year outcomes of spontaneous lumbar Cobb correction, P<0.05. Lumbar modifier and the interaction between the Cobb ratio and the percentage of the LIV rotation correction correlated significantly to 2-year outcomes of lumbar apical rotation correction, P<0.05.

CONCLUSION

The relationship between LIV rotation correction and spontaneous lumbar curve correction after selective thoracic fusion varied based on the patient's 3D preoperative curve characteristics. Patients with lumbar modifier C and apical vertebrae translation ratios >1.5 showed improved lumbar Cobb correction in 2-years when 50% or more LIV rotation correction was achieved surgically.

Radiological factors affecting post-operative global coronal balance in Lenke 5 C scoliosis

Background

Lenke 5 C curves are frequently associated with clinically and radiological coronal imbalance. Appropriate selection of proximal and distal levels of fusion is essential to ensure good coronal balance (CB). We aimed to evaluate radiological factors associated with (I) global CB in the early post-operative period; (II) late decompensation of CB; and (III) favourable spontaneous correction of CB on long term follow up.

Methods

Twenty-three Lenke type 5C scoliosis cases treated with selective posterior lumbar instrumentation were retrospectively evaluated. Pre-operative, early post-operative and late post-operative (>2 years) whole length radiographs were analysed. Cobb's angle, lumbar lordosis, coronal imbalance, lower instrumented vertebra (LIV) tilt and translation and upper instrumented vertebra (UIV) tilt and translation were measured. The proximal and distal fusion levels were noted and correlated with post-operative CB.

Results

There were 21 females and 2 males with a mean follow up of 36 months. The mean pre-operative cobb angle was 55°±13.26°, which corrected to 14.7°±8.84° and was maintained on follow up. Eight patients had early post-operative coronal imbalance with spontaneous resolution seen in six cases on long term follow-up. At final follow-up, four cases had coronal imbalance (persistent imbalance since early post-operative period =2; late decompensation =2). In cases with early imbalance 5/8 cases had a pre-operative LIV tilt of ≥25°. All four patients with coronal imbalance at final follow-up had pre-operative LIV tilt ≥25°. Radiographic parameters which correlated with post-operative coronal imbalance were pre-operative LIV tilt (r=0.64, P=0.001), pre-operative LIV translation (r=0.696, P<0.001), pre-operative UIV translation (r=0.44, P=0.030), post-operative LIV tilt (r=0.804, P<0.001), and post-operative UIV tilt (r=0.62, P=0.001).

Conclusions

In Lenke 5C scoliosis, a pre-operative LIV tilt ≥25° significantly correlates with post-operative global coronal imbalance. Increasing UIV tilt may be a factor that accounts for improvement of CB in late follow-up period.

Radiographic evaluation of posterior selective thoracolumbar or lumbar fusion for moderate Lenke 5C curves

INTRODUCTION

Posterior selective thoracolumbar or lumbar (TL/L) fusion with pedicle screw constructs for adolescent idiopathic scoliosis (AIS) has been studied in a few researches. However, few studies have discussed the indication for selective TL/L fusion and the behaviors of its adjacent disc angle. The present study aims to discuss the indication for posterior selective TL/L fusion and the behavior of the adjacent disc angle.

METHODS

45 consecutive cases of AIS undergoing posterior selective TL/L fusion were retrospectively evaluated, with an average follow-up of 36 months. Radiographs were reviewed to determine the coronal curve magnitude and the sagittal alignment preoperatively, postoperatively and at final follow-up. Thoracic curves in groups A had a correction loss of more than 5°, while thoracic curves in group B had a correction loss of not more than 5°.

RESULTS

The coronal curve magnitude of the TL/L curve averaged 44° preoperatively and it was corrected to 6° immediately with a correction rate of 84.8 %. At final follow-up it was 9° with a correction loss of 3°. The minor thoracic curve was 26° preoperatively, and the convex side bending curve magnitude averaged 8° with a flexibility of 72.7 %. It was corrected to 13° immediately with a spontaneous correction of 48.5 %. At final follow-up it was 14° with a correction loss of 1°. UIVA decreased from 4° to 2° after surgery, and it was 2° at final follow-up. LIVA decreased from 7° to 4° after surgery, and it was 5° at final follow-up. Maximal correction of TL/L curves in group A is significantly less than that in group B. 1 patient received revision surgery to fuse the progressive thoracic curve.

CONCLUSION

Posterior selective TL/L fusion with pedicle screw constructs allows for spontaneous thoracic correction and maintains coronal and sagittal balance during the follow-up. Maximal correction instead of undercorrection was recommended for moderate Lenke 5C curves. Disc wedging could be improved after surgery and well maintained during the follow-up.

Lenke 5C Curves in Adolescent Idiopathic Scoliosis: Anterior vs Posterior Selective Fusion

BACKGROUND

The optimal treatment of Lenke 5C curves in adolescent idiopathic scoliosis is still unclear.

OBJECTIVE

To compare the outcomes and the spontaneous correction behavior between anterior and posterior selective fusion techniques in a large case series.

METHODS

Demographic and surgical data for patients with Lenke 5C curves treated with anterior or posterior fusion were collected from July 2002 to September 2011. Clinical assessment and radiographic parameters were compared preoperatively and postoperatively and at a minimum of 2 years of follow-up.

RESULTS

Fifty-three Lenke 5C adolescent idiopathic scoliosis cases with an average follow-up of 4 years (range, 2-9.6 years) were included. The clinical scores were similar between the 2 groups. Postoperative major thoracic curvature changes were similar. The minor thoracic curve demonstrated a higher spontaneous correction rate in the posterior group. At follow-up, the minor thoracic curve showed a greater loss of correction in the posterior group, and finally both groups were comparable. Surgical time, intraoperative blood loss, and complications were comparable. A total of 5 patients had a final thoracic curve larger than the preoperative degrees.

CONCLUSION

Selective fusion of the major thoracolumbar/lumbar curve in Lenke 5C adolescent idiopathic scoliosis can be achieved by anterior and posterior techniques. The spontaneous correction of the unfused thoracic curve was comparable after an average of 4 years follow-up.

The Spontaneous Development of Cosmetic Shoulder Balance and Shorter Segment Fusion in Adolescent Idiopathic Scoliosis With Lenke I Curve: A Consecutive Study Followed Up for 2 to 5 Years

STUDY DESIGN

A single-center, retrospective, consecutive case series.

OBJECTIVE

To evaluate the spontaneous development of cosmetic shoulder balance (SDCSB) after surgery and to investigate the feasibility of shorter segment fusion in adolescent idiopathic scoliosis (AIS) with Lenke I curve.

SUMMARY OF BACKGROUND DATA

Upper instrumented vertebrae (UIV) at a more proximal level are always chosen to keep postoperative shoulder balance in AIS. In the guidelines of Rose and Lenke proposed in 2007, for Lenke I right thoracic curves, UIV should be T4 or T5 when the right shoulder is elevated preoperatively, T4 or T3 if the shoulders are level, and T2 when the left shoulder is elevated. Cosmetic shoulder balance (CSB), however, corrects and improves itself postoperatively.

METHODS

Seventy-five consecutive AIS patients with Lenke I curves were followed up for 2 to 5 years postoperatively. Twenty patients (26.7%) selected UIV at the caudal levels in the guidelines of Rose and Lenke (T5 when patients were with right shoulder elevated preoperatively, T4 when patients were with even shoulders preoperatively). Forty-two patients (56.0%) selected UIV at more caudal levels than those suggested by the guidelines. In this study, UIV at the caudal levels in the guidelines and UIV at more caudal levels than those suggested by the guidelines were shorter segment fusion. CSB was measured from photographs. Spinal Appearance Questionnaire (SAQ) was acquired for subjective evaluation of shoulder balance.

RESULTS

At last follow-up, the main thoracic curve was 19.5° ± 10.4°, the coronal balance improved to 0.7 ± 0.6 cm, and T2-T12 kyphosis was 34.4° ± 10.8°. At preoperation, immediate postoperation, and last follow-up, the measurements of CSB were 1.1 ± 0.7 cm (range: -2.4 to 1.7 cm), 0.9 ± 0.6 cm (range: -0.8 to 3.1 cm), and 0.6 ± 0.4 cm (range: -0.6 to 1.5 cm). At the three time points, numbers of patients with -1.0 cm < CSB < 1.0 cm were 28 (37.3%), 46 (61.3%), and 70 (93.3%), respectively. There was significant difference between the measurements of CSB at immediate postoperation and at last follow-up (t = 3.6, P < 0.001). At last follow-up, 74 (98.7%) patients perceived even shoulders in SAQ.

CONCLUSION

SDCSB plays an important role in regaining shoulder balance after surgery in AIS. The shorter segment fusion is feasible in treating AIS patients with Lenke I curves.

LEVEL OF EVIDENCE

4.

Selective versus nonselective thoracic fusion in Lenke 1C curves: a meta-analysis of baseline characteristics and postoperative outcomes

OBJECT

Lenke 1C curves are challenging to manage surgically due to the structural thoracic deformity and nonstructural lumbar curve. Selective thoracic fusion (STF) is considered the standard of care because it preserves motion of the lumbar segment, yet nonselective STF (NSTF) remains prevalent. This study aims to identify baseline patient characteristics that drive treatment and to compare postoperative outcomes for both procedures.

METHODS

Studies that compared baseline and postoperative demographic data, health-related quality of life (HRQL) questionnaires, and radiographic parameters of patients with Lenke 1C curves undergoing STF or NSTF were identified for meta-analysis. The effect measure is expressed as a mean difference (MD) with 95% CI. A positive MD signifies a greater STF value, or a mean increase within the group.

RESULTS

One prospective and 6 retrospective case-control studies with sample size of 488 patients (344 STF and 144 NSTF) were identified. Baseline age, sex, and HRQLs were equivalent, except for better scores in the STF group for the Scoliosis Appearance Questionnaire (SAQ): Unrelated to Deformity item (3.47 vs 3.88, p = 0.01) and the Spine Research Society questionnaire, Item 22: Pain (4.13 vs 3.92, p = 0.04). Radiographic findings were significantly worse in NSTF, as measured by the thoracolumbar/lumbar (TL/L) Cobb angle (MD: -4.29°, p < 0.01) and TL/L apical vertebral translation (AVT) (MD: -6.08, p < 0.01). Radiographic findings significantly improved in STF, as measured in the main thoracic (MT) Cobb angle (MD: -27.78°, p < 0.01), TL/L Cobb angle (MD: -16.24°, p < 0.01), MT:TL/L Cobb ratio (MD: -0.21, p < 0.01), coronal balance (MD: 0.47, p = 0.02), and thoracic kyphosis (MD: 7.87°, p < 0.01); and in NSTF in proximal thoracic (PT) Cobb angle (24° vs 14.1°, p < 0.01), MT Cobb angle (53.5° vs 20.5°, p < 0.01), and TL/L Cobb angle (41.6° vs 16.6°, p < 0.01). Postoperative TL/L Cobb angle (23.1° vs 16.6°, p < 0.01) was significantly higher in STF; but PT Cobb angle, MT Cobb angle, and MT:TL/L Cobb ratio are equivalent.

CONCLUSIONS

Patients with larger lumbar compensatory curves displaying a larger degree of coronal translation, as measured by the TL/L AVT, are more likely to undergo an NSTF. Contrary to established guidelines, larger MT curve magnitudes and MT:TL/L Cobb angle ratios have not been found to influence the decision to pursue a selective thoracic fusion. Although overall both STF and NSTF groups are found to have effective postoperative coronal balance, the STF group has only modest improvements in the lumbar curve position as determined by a relatively unchanged TL/L AVT. Furthermore, surgeons may prefer NSTF in patients who may have a worse overall perception of their spinal deformity as measured by HRQL measures of pain and desire for appearance change.

Predictability of spontaneous thoracic curve correction after anterior thoracolumbar correction and fusion in adolescent idiopathic scoliosis. A retrospective study on a consecutive series of 29 patients with a minimum follow-up of 2 years

BACKGROUND CONTEXT

According to the Lenke classification, a Type 5 adolescent idiopathic scoliosis can be surgically treated with selective anterior thoracolumbar or lumbar fusion.

PURPOSE

This study aims to predict the spontaneous correction of the unfused thoracic curve after anterior thoracolumbar fusion and to study whether age is of influence on this predictability.

STUDY DESIGN

Retrospective study on a consecutive series of patients.

PATIENT SAMPLE

Of a consecutive series of 38 patients with idiopathic thoracolumbar scoliosis, Lenke type 5, 29 patients were included in the study. All patients were treated with anterior spinal fusion and instrumentation. A minimum follow-up of 2 years was available for all patients (mean, 4 years; range, 2-17 years). To investigate the influence of age on the outcome, we divided the group into two subgroups: an adolescent (n=13) and an adult age group (n=16). The mean age in the adolescent group was 17 (range, 13-21 years) and 38 years (range, 22-54 years) in the adult group.

OUTCOME MEASURES

Physiological measures include coronal Cobb angle, apical vertebral translation (AVT) and apical vertebral rotation (AVR), shoulder tilt, trunk shift, L4 tilt, and pelvic tilt. Relative corrections were computed for the thoracolumbar and thoracic curves in each patient using the following formula: (preoperative curve-postoperative curve)/preoperative curve×100 (%). The correlation coefficient between the relative (%) corrections of the thoracic and thoracolumbar curves was calculated for the whole group as for the two age subgroups.

METHODS

For radiographic evaluation, we used standing anteroposterior and lateral projections of the thoracolumbar spine to determine Cobb angle, AVT and AVR, and coronal balance.

RESULTS

Both the thoracolumbar and thoracic curves in the whole group improved after surgery (45% and 19%, respectively, p<.01). In the adolescent age group, a significant correlation between the relative (%) correction of the thoracolumbar curve and the relative (%) correction of the thoracic curve was found (R=0.704; p=.01) and between age and relative (%) correction of the thoracic curve (R=-0.805; p<.01).

CONCLUSIONS

These results show that the spontaneous correction of the thoracic curve is a reflection of the thoracolumbar curve correction in adolescent thoracolumbar idiopathic scoliosis. Moreover, the predictability of the thoracic curve correction in the individual patient seems to decrease with increasing age of the patient.

Comparison of Anteroposterior to Posterior-Only Correction of Scheuermann's Kyphosis: A Matched-Pair Radiographic Analysis of 92 Patients

STUDY DESIGN

Retrospective radiographic benchmark study.

OBJECTIVE

To evaluate the amount of instrumented correction obtained from a combined anterior/posterior (A/P) versus posterior-only (post-only) approach for Scheuermann's kyphosis.

SUMMARY OF BACKGROUND DATA

An A/P approach was thought to optimize correction; however, instrumentation advances using pedicle screws allow treatment through an all-posterior approach.

METHODS

A total of 166 Scheuermann's kyphosis patients were treated between 2 centers: 90 by combined A/P approach at 1 center and 76 by post-only at the second center. From the 166 patients, a matched cohort of 92 (46 from each) was established according to preoperative sagittal (±10°) and hyperextension (HE) Cobb (±10°) measurements and matched for age and gender.

RESULTS

In the matched-pair group, average preoperative sagittal Cobb angles were 75.9° for the A/P group versus 78.8° for the post-only group (p = .2). The HE Cobb angles were similar (52.4° vs. 51.1°; p = .6). They showed similar corrections (33.7° vs. 30.6°; p = .3) and postoperative Cobb measurements (43.4° vs. 47.1°; p = .2) as well. The number of fusion levels was 9 in the A/P group and 12 in the post-only group; the difference yielded significance (p = .02).

CONCLUSIONS

The A/P and post-only approaches averaged similar degrees of correction. The A/P patients were likely to correct more than their preoperative HE sagittal Cobb measurement, whereas the post-only group corrected close to their preoperative HE measurement. The number of fusion levels was larger with the post-only group.

Results of selective thoracic versus nonselective fusion in Lenke type 3 curves

STUDY DESIGN

A retrospective analysis of a prospectively collected multicenter database.

OBJECTIVE

To identify the radiographical and clinical outcomes in Lenke 3 curves fused selectively (S) versus nonselectively (NS).

SUMMARY OF BACKGROUND DATA

Surgical treatment options for Lenke 3 curves include fusion of both curves (NS) or selective thoracic curve fusion (S). Selective fusion of the thoracic curve spares lumbar motion segments; however, it may result in marked residual deformity.

METHODS

A prospectively collected multicenter database was retrospectively reviewed for adolescent idiopathic scoliosis Lenke 3 curves treated with posterior spinal fusion with a minimum of 2 years of follow-up. Patients were divided into 2 groups: NS (nonselective fusion) and S (selective thoracic fusion). Radiographical and clinical data were compared between the groups using the unpaired Student t test and analysis of variance.

RESULTS

A total of 74 patients met our inclusion criteria, with 49 (66.2%) in the NS group and 25 (33.8%) in the S group. Overall, both groups were similar preoperatively except for lumbar Cobb (NS = 56.3°, S = 47.2°, P < 0.001), lumbar lordosis (NS = 56.9°, S = 67.2°, P = 0.001), lumbar rotational prominence (NS = 11.2°, S = 8.2°, P < 0.05), and lumbar apical translation (NS = 3.2 cm, S = 1.9 cm, P < 0.05). Postoperatively, NS fusion demonstrated significantly less coronal imbalance of 2 cm or less (NS = 10.2%, S = 56.0%, P < 0.001), better lumbar curve correction (NS = 68.2%, S = 51.9%, P < 0.001), better lumbar apical translation correction (NS = 1.2 cm, S = 2.1 cm, P < 0.01), and better percent correction of the lumbar prominence (NS = 66.5%, S = 40.4%, P < 0.05). Scoliosis Research Society Questionnaire 22 scores at 2 years were similar between the groups.

CONCLUSION

Despite preoperatively smaller lumbar curves with less apical translation and lumbar prominence, most patients with selective fusions were out of balance postoperatively and had inferior radiographical outcomes as compared with their nonselective comparison cohort with similar patient-reported outcomes. Long-term follow-up is required to determine whether the trade-off of sparing motion segments at the expense of somewhat lessened radiographical outcomes is worthwhile.

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

STUDY DESIGN

Retrospective radiographical review.

OBJECTIVE

To demonstrate that the structural and noncompensatory Lenke 3 and 4C lumbar curves could be nonstructural and compensatory.

SUMMARY OF BACKGROUND DATA

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

LEVEL OF EVIDENCE

2.

Guan-Din method: a novel surgical technique for selective thoracic fusion to maximize the rate of selective thoracic fusion and compensatory correction

STUDY DESIGN

Retrospective radiographical review.

OBJECTIVE

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.

SUMMARY OF BACKGROUND DATA

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.

METHODS

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).

RESULTS

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.

CONCLUSION

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.

LEVEL OF EVIDENCE

4.

Lenke 1C and 5C spinal deformities fused selectively: 5-year outcomes of the uninstrumented compensatory curves

STUDY DESIGN

Multicenter review of prospectively collected data.

OBJECTIVE

To analyze the natural history of uninstrumented compensatory curves prospectively during a 5-year postoperative period in patients with selectively fused Lenke type 1C and 5C adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

After a selective fusion for 1C and 5C adolescent idiopathic scoliosis curve types, there is concern that uninstrumented compensatory curves will continue to progress over time. However, to date, there have been no studies using prospectively collected data beyond 2 years to determine the natural history of these uninstrumented compensatory curves.

METHODS

Lenke 1C and 5C adolescent idiopathic scoliosis cases, prospectively collected from a multicenter study were analyzed. All patients underwent a selective fusion (1C only thoracic curve fused; 5C only thoracolumbar/lumbar curve fused). Preoperative, first-erect, 1-year, 2-year, and 5-year postoperative coronal, sagittal, and axial (Perdriolle) radiographical outcomes were compared using repeated measures analysis of variance with Bonferroni post hoc comparisons (P < 0.05).

RESULTS

Twenty-four selectively fused Lenke 1C curves and 21 selectively fused Lenke 5C curves were reviewed. Preoperative compensatory curve Cobb angles were 40° ± 6° and 25° ± 9°, respectively. In Lenke 1C curves, the uninstrumented compensatory lumbar curves were corrected by 32% ± 16% at first erect, 44% ± 17% correction at 1 year, 38% ± 15% correction at 2 years, and 39% ± 19% at 5 years. In Lenke 5C curves, the uninstrumented compensatory thoracic curves were corrected by a mean of 37% ± 29% at first erect, 42% ± 29% at 1 year, 37% ± 29% at 2 years, and 30% ± 23% at 5 years. The sagittal and axial measures of the compensatory curves remained stable during the postoperative period.

CONCLUSION

In Lenke 1C and 5C adolescent idiopathic scoliosis deformity patterns fused selectively, the uninstrumented compensatory curves adjust to match the instrumented primary curve and do not seem to progress between 1 and 5 years postoperatively.

Adolescent scoliosis classification and treatment

Adolescent idiopathic scoliosis (AIS) affects up to 3% of the population. It can be stratified by curve type according to the Lenke classification. This classification system incorporates curve magnitude, flexibility, the lumbar modifier, and the sagittal plane. The Lenke classification serves as a guide for selection of levels for surgical treatment of AIS. Surgical treatment of AIS includes anterior and posterior approaches; most AIS is treated through a posterior approach. Surgical goals include maximizing correction in the coronal, sagittal, and axial planes.

Adding thoracic fusion levels in Lenke 5 curves: risks and benefits

STUDY DESIGN

Multicenter; review of prospectively collected data.

OBJECTIVE

To determine the risks and potential benefits of nonselective versus selective fusion in a matched set of patients with Lenke 5 curves.

SUMMARY OF BACKGROUND DATA

The Lenke classification suggests a limited thoracolumbar/lumbar fusion for type 5 curves, although many experienced adolescent idiopathic scoliosis surgeons, at times, include a fusion of the thoracic curve. METHODS.: Prospectively collected cases from a multicenter database were analyzed. Patients with Lenke type 5 scoliosis curves were divided into 2 groups: 109 selective or short (only thoracolumbar/lumbar curve fused), and 41 nonselective or long (both thoracolumbar/lumbar and thoracic curves fused). Patients were then matched on the basis of the preoperative radiographical and clinical measures. Two-year postoperative radiographical and clinical outcomes were compared, using analysis of variance, with Bonferroni correction (P < 0.008).

RESULTS

Twenty-nine matched pairs (58 patients) with Lenke 5 curves were identified. There were no preoperative differences between groups in age, thoracic or lumbar Cobb angle, curve flexibility, thoracic kyphosis, clinical trunk flexibility, or Scoliosis Research Society outcomes questionnaire scores. Postoperatively, patients in the nonselective group exhibited greater coronal correction for thoracic (residual Cobb; 22° vs. 12°) and lumbar curves (residual Cobb; 19° vs. 13°). However, the longer fusions had significantly less thoracic kyphosis (27° vs. 18°), truncal side bending (14 vs. 10 cm), and rotational flexibility (53° vs. 42°). There was no difference in clinical balance or Scoliosis Research Society questionnaire, version 22, scores.

CONCLUSION

Adolescent idiopathic scoliosis surgeons attempt to achieve balanced correction with the fewest motion segments fused. Our data suggest that fusion of the thoracic curve in primary thoracolumbar scoliosis may improve coronal correction, but at the cost of decreased thoracic kyphosis and clinical flexibility 2 years postoperatively.

Reciprocal sagittal alignment changes after posterior fusion in the setting of adolescent idiopathic scoliosis

PURPOSE

Surgical adolescent idiopathic scoliosis (AIS) management can be associated with loss of thoracic kyphosis and a secondary loss of lumbar lordosis leading to iatrogenic flatback. Such conditions are associated with poorer clinical outcomes during adulthood. The aim of this study was to evaluate sagittal plane reciprocal changes after posterior spinal fusion in the setting of AIS.

METHODS

Thirty consecutive adolescents (mean age 14.6 years) with AIS Lenke 1, 2 or 3 were included in this retrospective study with 2 year follow-up. Full-spine standing coronal and lateral radiographs were obtained preoperatively, at 3 and 24 months postoperatively. Coronal Cobb angle, thoracic kyphosis (TK) and lumbar lordosis (LL) were measured. Surgical procedure was similar in all the cases, with use of pedicular screws between T11 and the lowest instrumented vertebra (≥L2), sublaminar hooks applied in compression at the upper thoracic level and sub-laminar bands and clamps in the concavity of the deformity. Statistical analysis was done using t test and Pearson correlation coefficient.

RESULTS

Between preoperative and last follow-up evaluations a significant reduction of Cobb angle was observed (53.6° vs. 17.2°, p < 0.001). A significant improvement of the instrumented thoracic kyphosis, TK (19.7° vs. 26.2°, p < 0.005) was noted, without difference between 3 and 24 months postoperatively. An improvement in lumbar lordosis, LL (43.9° vs. 47.3°, p = 0.009) was also noted but occurred after the third postoperative month. A significant correlation was found between TK correction and improvement of LL (R = 0.382, p = 0.037), without correlation between these reciprocal changes and the amount of coronal correction.

CONCLUSION

Results from this study reveal that sagittal reciprocal changes occur after posterior fusion when TK is restored. These changes are visible after 3 months postoperatively, corresponding to a progressive adaptation of patient posture to the surgically induced alignment. These changes are not correlated with coronal plane correction of the deformity. In the setting of AIS, TK restoration is a critical goal and permits favorable postural adaptation. Further studies will include pelvic parameters and clinical scores in order to evaluate the impact of the noted reciprocal changes.

Evolution of the curve patterns during brace treatment for adolescent idiopathic scoliosis

The curve pattern of idiopathic scoliosis is important for making decisions concerning bracing. However, whether the curve pattern changes during brace treatment have not been fully documented. The aim of this study was to investigate the changes of curve pattern during brace treatment in skeletally immature patients with adolescent idiopathic scoliosis (AIS).

METHODS

From January 2002 to January 2011, AIS patients treated with a Boston or Milwaukee brace were recruited after meeting the following inclusion criteria: older than 10 years of age at initiation of bracing; having a Cobb angle of 25°-40°; with a Risser sign 0-2; being regularly followed until the weaning of brace or the necessity of surgical treatment; and without history of previous treatment. A total of 130 female and 11 male AIS patients were included. The mean age was 12.9 years at initiation of bracing, and the female patients were, on average, 2.7 months past menarche. The mean follow-up period was 2.6 years (range 1.0-5.5 years). The definitions of changes in curve patterns were divided into four categories as follows: (1) shift of the apex of the main curve; (2) change in the curve span of more than two vertebrae; (3) change in the main curve type with regard to the apex location; and (4) change of curve direction. The patients were divided into two groups. Group A was comprised of patients who had experienced one or more categories of curve pattern changes, and Group B was comprised of those who had not.

RESULTS

Of these 39 patients, 14 had apex shifting, 2 underwent curve span changes, 22 experienced changes in the main curve type, and one female had both changes in the apex and curve span. At the initiation of bracing, patients in Group A demonstrated significantly lower menarchal status (P = 0.018) and lower Risser grade (P = 0.025) than those in Group B. The difference in the percentage of patients who underwent Boston bracing between the two groups was statistically significant (41.5 % for Group A vs. 24.0 % for Group B, P = 0.023).

CONCLUSION

Changes in curve pattern can occur during brace treatment. Patients with less skeletal maturity and those treated with a Boston brace are more susceptible to this phenomenon.

Avaliação postural por fotogrametria em pacientes com escoliose idiopática submetidos à artrodese: estudo piloto

INTRODUÇÃO: A escoliose é uma alteração tridimensional das vértebras, caracterizada por um desvio lateral. A quantificação do desvio lateral após correção cirúrgica poderia auxiliar quanto ao prognóstico da doença e direcionar na reabilitação. OBJETIVOS: Comparar as alterações posturais no pré e pós-operatório de artrodese da coluna vertebral em pacientes com escoliose idiopática do adolescente. MATERIAIS E MÉTODOS: Foram avaliados nove pacientes com escoliose idiopática entre 11 e 18 anos de idade. Eles foram fotografados no pré-operatório e após quatro semanas. Os pontos anatômicos foram marcados sobre a pele por meio de fixação de bolas de isopor. Para análise das fotografias, estas foram enviadas para um computador com o programa SAPO previamente instalado. Os dados foram analisados utilizando o teste t pareado. RESULTADOS: Foram observados: diminuição significante no ângulo axilar esquerdo (EACE) e no ângulo Q esquerdo (AQE), aumento no ângulo de inclinação do tronco na vista anterior (ITA), no ângulo formado entre o ponto mais alto do trapézio e o manúbrio esquerdo (TAME), no ângulo da cifose torácica direita (CTD) e lordose lombar direita e esquerda (LLD e LLE) e no ângulo tibiotársico esquerdo (ATTE). Houve aumento nas distâncias entre C7, T3 e T7 à espinha ilíaca póstero-superior direita (DC7, DT3 e T7) e C7, T3 e L4 à espinha ilíaca póstero-superior esquerda (EC7, ET3 e EL4). CONCLUSÃO: Foi constatada alteração significativa nos ângulos EACE, AQE, ITA, TAME, CTD, LLD, LLE, ATTE e nas distâncias DC7, DT3, DT7, EC7, ET3 e EL4 quatro semanas após a cirurgia de artrodese.

Segmental correction of adolescent idiopathic scoliosis by all-screw fixation method in adolescents and young adults. minimum 5 years follow-up with SF-36 questionnaire

Background

In our institution, the fixation technique in treating idiopathic scoliosis was shifted from hybrid fixation to the all-screw method beginning in 2000. We conducted this study to assess the intermediate -term outcome of all-screw method in treating adolescent idiopathic scoliosis (AIS).

Methods

Forty-nine consecutive patients were retrospectively included with minimum of 5-year follow-up (mean, 6.1; range, 5.1-7.3 years). The average age of surgery was 18.5 ± 5.0 years. We assessed radiographic measurements at preoperative (Preop), postoperative (PO) and final follow-up (FFU) period. Curve correction rate, correction loss rate, complications, accuracy of pedicle screws and SF-36 scores were analyzed.

Results

The average major curve was corrected from 58.0 ± 13.0° Preop to 16.0 ± 9.0° PO(p < 0.0001), and increased to 18.4 ± 8.6°(p = 0.12) FFU. This revealed a 72.7% correction rate and a correction loss of 2.4° (3.92%). The thoracic kyphosis decreased little at FFU (22 ± 12° to 20 ± 6°, (p = 0.25)). Apical vertebral rotation decreased from 2.1 ± 0.8 PreOP to 0.8 ± 0.8 at FFU (Nash-Moe grading, p < 0.01). Among total 831 pedicle screws, 56 (6.7%) were found to be malpositioned. Compared with 2069 age-matched Taiwanese, SF-36 scores showed inferior result in 2 variables: physical function and role physical.

Conclusion

Follow-up more than 5 years, the authors suggest that all-screw method is an efficient and safe method.

Postoperative spinal alignment remodeling in Lenke 1C scoliosis treated with selective thoracic fusion

BACKGROUND CONTEXT

Selective thoracic fusion may cause spinal imbalance in certain patients; how the spinal alignment changes over time after surgery is highly correlated with the final spinal balance.

PURPOSE

To investigate how spinal alignment changes over time after selective thoracic fusion and how spinal alignment remodeling affects spinal balance.

METHODS

All adolescent idiopathic scoliosis (AIS) cases surgically treated in our institution between 2002 and 2008 were reviewed. Inclusion criteria were as follows: Lenke 1C scoliosis patients treated with posterior pedicle screw-only constructs; the lowest instrumented vertebra (LIV) ended at L1 level or above; and 2-year radiographic follow-up. Standing anteroposterior and lateral digital radiographs from four different time points (preoperatively, immediately, 3 months, and 2 years postoperatively) were reviewed. In each standing anteroposterior radiograph, the center sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, and the translation (deviation from the CSVL) of some key vertebrae was measured, such as the LIV, LIV+1 (the first vertebra below LIV), LIV+2 (the second vertebra below LIV), LIV+3 (the third vertebra below LIV), lumbar apical vertebra (AV), thoracic AV, and T1. Additionally, the Cobb angles of the major thoracic and lumbar curves were measured at different time points, and the correction rates were calculated. Furthermore, clinical photographs of the patients from the back were taken preoperatively and postoperatively.

RESULTS

Of 278 AIS patients reviewed, 29 met the inclusion criteria. The continuous follow-up of our present study revealed an interesting phenomenon: postoperative spinal alignment remodeling. A hypothetical criterion was established to determine the onset of the phenomenon. By means of a series of analyses, the criterion was validated. The results of our present study showed that selective thoracic fusion tended to cause leftward spinal imbalance in these Lenke 1C AIS patients. Twenty of the 29 patients had leftward spinal imbalance immediately after surgery. Although some patients regained spinal balance through postoperative spinal alignment remodeling, 11 patients remained imbalanced at 2-year follow-up.

CONCLUSIONS

Selective thoracic fusion is prone to cause leftward spinal imbalance in Lenke 1C scoliosis patients. Postoperative spinal alignment remodeling can facilitate recovery of spinal balance in some patients. Postoperative spinal imbalance in Lenke 1C scoliosis patients could be prevented by selecting stable vertebra or the vertebrae above as LIV, checking the balance condition during surgery, or considering ratio criteria when selecting candidates for selective thoracic fusion.

Lowest instrumented vertebra selection in Lenke 3C and 6C scoliosis: what if we choose lumbar apical vertebra as distal fusion end?

PURPOSE

The aim of this study was to investigate whether or not post-op curve behaviour differs due to different choices of lowest instrumented vertebra (LIV) with reference to lumbar apical vertebra (LAV) in Lenke 3C and 6C scoliosis.

METHODS

We reviewed all the AIS cases surgically treated in our institution from 2002 through 2008. Inclusion criteria were as follows: (1) patients with Lenke 3C or 6C scoliosis who were treated with posterior pedicle screw-only constructs; (2) 2-year radiographic follow-up. All the included patients were categorized into three groups based on the relative position of LIV and LAV: Group A-the LIV was above the LAV; Group B-the LIV was at the LAV; Group C-the LIV was below the LAV. All the radiographic parameters were then compared among the groups. All image data were available in our picture archiving and communication systems. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four times (pre-op, post-op, 3-month and 2-year). In each standing AP radiograph, centre sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, followed by measuring T1-CSVL, LIV-CSVL, (LIV + 1)-CSVL, LAV-CSVL and thoracic AV-CSVL distance. In addition, the Cobb angles of major thoracic and lumbar curves were measured at the four times and the correction rates were then calculated.

RESULTS

Of the 278 patients reviewed, 40 met the inclusion criteria; 11 of these were included in Group A (LIV above LAV), another 11 in Group B (LIV at LAV) and the remaining 18 in Group C (LIV below LAV). At 2-year follow-up, the lumbar vertebrae such as LIV, LIV + 1 and LAV were all more deviated than before surgery in Group A (LIV above LAV), whereas in Group B and C (LIV at and below LAV) they were all less deviated than before surgery. No significant differences were found in thoracic or lumbar correction rate, global coronal balance and incidence rate of trunk shift among the three groups.

CONCLUSION

In conclusion, in Lenke 3C and 6C scoliosis, post-op lumbar curve behaviour differs due to different choices of LIV with reference to LAV, that is, the deviation of lumbar curve improves when the LIV is either at or below the LAV but deteriorates when the LIV is above the LAV. Although the greatest correction occurs when the LIV is below the LAV, choosing LAV as LIV can still be the optimal option in certain cases, since it can yield similar correction while preserving more lumbar mobility and growth potential.

Extensive fusion for Lenke 3C and 6C scoliosis: a two year radiographic follow-up

PURPOSE

To investigate the correction effectiveness, incidence rate of distal adding on, and post-operative spinal balance in Lenke 3C and 6C AIS treated with extensive fusion using posterior pedicle screw-only constructs.

METHODS

We reviewed all AIS cases surgically treated in our institution between 2002 and 2008. The inclusion criteria were as follows: (1) Lenke 3C or 6C scoliosis patients who were treated with extensive fusion using posterior pedicle screw-only constructs; (2) minimum two year radiographic follow-up; (3) the lowest instrumented vertebra (LIV) ended at L2, L3 or L4 level. All image data were available in our picture archiving and communication systems (PACSs) , and all radiographic measurements were performed. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four different time points (pre-op, post-op, three months, and two years). In each standing AP radiograph, CSVL (center sacral vertical line, the vertical line bisecting the proximal sacrum) was first drawn, followed by measurement of the translation (deviation from the CSVL) of some key vertebrae, such as the lowest instrumented vertebra (LIV), LIV + 1 (the first vertebra below LIV), lumbar apical vertebra, thoracic apical vertebra and T1, enabling depiction of how translation of different parts of the spine changes over time. Additionally, the Cobb angles of major thoracic and lumbar curves were measured at the different time points and the correction rate was calculated.

RESULTS

Of the 278 patients reviewed, 25 met the inclusion criteria. Immediately after surgery, satisfactory corrections were achieved from the perspective of not only Cobb angle but also vertebral translation. And the corrections were well retained in the following two years. The incidence rate of distal adding-on was low in this group of patients. In the course of two years following surgery, only six patients had an increase of greater than 5 mm in LIV + 1 translation, and among which only two patients had greater than 10 mm. Regarding global balance, overall, it neither improved nor deteriorated after extensive fusion. Furthermore, trunk shift was found in only three patients at two year follow-up.

CONCLUSIONS

In Lenke 3C and 6C scoliosis, extensive fusion can produce satisfactory corrections from the perspectives of both Cobb angle and vertebral translation and rarely causes significant distal adding-on, global imbalance or trunk shift.

Taking the shoulders and pelvis into account in the preoperative classification of idiopathic scoliosis in adolescents and young adults (a constructive critique of King's and Lenke's systems of classification)

INTRODUCTION

The surgical strategies to treat idiopathic scoliosis on adolescents and young adults need a basic reliable classification. King's and Lenke's classification are inappropriate because they fail to take shoulders and pelvis into account.

METHODS

We propose the answer for the following three questions: 1. Why are we challenging King's and Lenke's systems of classification? 2. How many frontal and possibly sagittal curves do we need to be able to develop a strategy which is applicable to almost all cases? 3. How should scoliotic curves be classified?

RESULTS

In double thoracic and lumbar (thoracic predominant) scoliosis, the concepts of "pelvis included" and "pelvis excluded" are not simply based on a semantic distinction, but correspond to different physiopathological entities and require different surgical strategies. In double thoracic curves the concepts of "real double thoracic" and "potential double thoracic" curves are keys to obtain post operative shoulder balance. In lumbar scoliosis the concepts of "real lumbar" and "lumbosacral" curves are necessary to compare results of posterior or anterior approach in surgical strategies. The system proposed in this work involves ten basic curves.

CONCLUSION

The surgical strategies used to treat idiopathic scoliosis in adolescents and young adults depend on the school of thought as to whether the anterior or posterior approach is preferable and the extent of the vertebral instrumentation. A consensus system of classification of scoliotic curves is required to compare the results obtained using various methods. This has been done in the improved version of King's system proposed here and should provide an efficient tool for use in comparative studies on surgical methods.

Selective thoracic fusion in adolescent idiopathic scoliosis: factors influencing the selection of the optimal lowest instrumented vertebra

STUDY DESIGN

Analysis of multicenter, prospectively collected data.

OBJECTIVE

To determine how selection of the lowest instrumented vertebra (LIV) relative to the stable vertebra (SV) and the end vertebra (EV) effects correction of the main thoracic curve, compensatory lumbar curve, and incidence of coronal decompensation after selective thoracic fusion.

SUMMARY OF BACKGROUND DATA

Traditionally, in Lenke type 1B and 1C curves, the LIV is selected as the SV; however, selecting the LIV continues to be controversial.

METHODS

Inclusion criteria were patients with adolescent idiopathic scoliosis (AIS) with Lenke type 1B, 1C, or 3C curves that had a selective thoracic fusion with the LIV from T11 to L1 (n=172). The patients were divided into three curve patterns on the basis of the relative position of SV and EV. Group SBE (stable below end) (n=93) had SV below EV, group SAE (stable at end) (n=66) had SV at the EV, and group EBS (end below stable) (n=13) has EV below SV. In addition, each group was divided into six subgroups based on the selected LIV: LIV above SV, at the SV, below SV, above EV, at the EV, and below EV. Each was compared for preoperative and 2-year postoperative radiographic parameters and clinical data.

RESULTS

In group SBE, the 2-year postoperative thoracic curve correction rate when the LIV was below the EV (64%+16%) was significantly greater than when the LIV was at the EV (54%+13%; P<0.001). The 2-year postoperative spontaneous lumbar curve correction (SLCC) rate similarly correlated with the LIV selection subgroups, 52%+20% and 43%+19%, respectively (P=0.03). In group SAE, the 2-year postoperative thoracic curve correction rate when the LIV was below the EV/SV (64%+14%) was significantly greater than when the LIV was at the EV/SV (52%+14%; P=0.004). The 2-year postoperative SLCC rate for group SAE similarly correlated with the LIV selection subgroup, 56%+16% and 38%+21%, respectively (P<0.01). In group EBS, the 2-year postoperative thoracic curve correction and SLCC rates were not significantly different among the LIV selection subgroups; however, the incidence of decompensation was 38%.

CONCLUSION

When performing a selective thoracic fusion of Lenke type 1B, 1C, and 3C AIS curves in which the SV was at/or below the EV, the greatest correction of the main thoracic and compensatory lumbar curves occurred when the LIV was at/or at least one level distal to the SV. This more distal LIV did not result in an increased rate of truncal imbalance.

Selective fusion for adolescent idiopathic scoliosis: a review of current operative strategy

Selective fusion of thoracic and thoracolumbar/lumbar curves in adolescent idiopathic scoliosis is a concept critically debated in the literature. While some surgeons strongly believe that a more rigid and straighter spine provides predictably excellent outcomes, some surgeons recommend a mobile and less straight spine. This topic is a crucial part of surgical treatment of idiopathic scoliosis, particularly in young patients who will deal with the stress of the fusion mass at the proximal and distal junctions over many years. This study will review the literature on various aspects of selective fusion.

Predicting the outcome of selective thoracic fusion in false double major lumbar "C" cases with five- to twenty-four-year follow-up

STUDY DESIGN

Retrospective radiographic and clinical study.

OBJECTIVE

To examine the long-term outcome of selective thoracic fusion (STF) performed for lumbar "C" modifier curves in adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

The efficacy of STF in lumbar "C" false double major curves is controversial. We examined the 5- to 24-year outcomes of patients with "C" lumbar curves who underwent STF at a single institution to determine which factors help predict successful outcome.

METHODS

Thirty-two patients (age, 14.8 ± 2.0 years) with a lumbar "C" modifier underwent primary STF and had minimum 5-year follow-up (mean, 6.8 years). All patients were fused distally to either T12 or L1. At latest follow-up, 18 were considered successful (group S), 2 required reoperation to accommodate worsening deformity (group R), and 12 were considered marginal outcomes (group M), as defined by >3 cm coronal imbalance (n = 5), >5 mm worsening of lumbar apical vertebra translation compared with preoperative (n = 4), >1 Nash-Moe grade worsening of lumbar apical vertebra rotation (n = 1), >10° thoracolumbar junction kyphosis which was at least 5° worse than preoperative (n = 5), and lumbar Cobb angle >5° worse than preoperative (n = 2). Clinical outcomes were determined by Scoliosis Research Society (SRS)-30 at final follow-up.

RESULTS

Of the multiple factors considered, 2-month postoperative standing lumbar sagittal alignment was most predictive for long-term outcome (P < 0.019 by Kruskal-Wallis ANOVA). Satisfactory outcomes had statistically significantly greater T12-S1 lordosis than those that were marginal (64.8° (group S) vs. 52.0° (group M); P = 0.014) or required reoperation (64.8° [group S] vs. 38.0° [group R]; P < 0.001). Traditionally considered variables such as apical vertebra rotation, apical vertebra translation, Cobb angle magnitudes, coronal and sagittal balance, and their respective thoracic-to-lumbar ratios were not independently significant.

CONCLUSION

Selective thoracic fusions performed for lumbar "C" modifier scoliotic deformities generally have excellent long-term radiographic and SRS-30 outcomes at 5- to 24-year follow-up. Care should be taken to ensure that overcorrection of the thoracic curve is not performed beyond the ability of the lumbar curve to compensate. Furthermore, consideration of selective thoracic fusion should not be ruled out simply because the patient may have a somewhat stiff lumbar curve based on side-bending radiographs.

Escoliose idiopática do adolescente King II (Lenke B e C): predição da descompensação coronal

OBJETIVO: Identificar os sinais radiográficos preditivos de descompensação do tronco em pacientes com EIA King II (Lenke B e C) submetidos a artrodese torácica seletiva com material de terceira geração. MÉTODOS: Foram avaliadas retrospectivamente as radiografias pré-operatórias e do último acompanhamento de 22 pacientes. A amostra foi dividida em dois grupos: pacientes compensados após o tratamento (n=18) e os pacientes que apresentaram descompensação coronal (n=4). Esses dois grupos foram comparados para analisar possíveis critérios radiográficos pré-operatórios preditivos da descompensação do tronco. RESULTADOS: Os pacientes que evoluíram com descompensação coronal do tronco apresentaram maior valor angular, maior translação e maior rotação da vértebra apical da curva lombar e maior obliqüidade de L4 em relação à pelve. Além disso, a relação entre a curva torácica para os critérios de valor angular, TVA e RVA foi menor, quando comparadas com os pacientes com boa evolução. CONCLUSÕES: Curvas lombares compensatórias com valor angular semelhante à curva torácica principal, com translação e rotação da vértebra apical elevadas e grande inclinação de L4 apresentam alta probabilidade de descompensação do tronco após o tratamento cirúrgico. O número pequeno de pacientes descompensados não permitiu definir valores preditivos destas variáveis.

Avaliação radiográfica da descompensação do tronco após artrodese seletiva torácica em portadores de escoliose idiopática do adolescente King II (Lenke B e C)

OBJETIVO: avaliar a incidência de descompensação radiográfica do tronco após a artrodese seletiva torácica com instrumental de 3º geração na escoliose idiopática do adolescente (EIA) King II (Lenke B e C) após acompanhamento mínimo de um ano. MÉTODOS: foram avaliadas retrospectivamente as radiografias pré-operatórias, pós-operatórias imediatas e do último acompanhamento de 22 pacientes tratadas no período de 1993 a 2007. Observou-se a porcentagem de correção da curva torácica e lombar pelo método de Cobb, e o balanço coronal do tronco do início e do final do acompanhamento foi avaliado pelos critérios da Scoliosis Research Society. RESULTADOS: após correção média da curva torácica de 56 ± 11% e da lombar de 49 ±13%, verificamos descompensação coronal imediata em seis pacientes (27,20%). Após acompanhamento médio de 65 meses, quatro pacientes (18,18%) estavam com o tronco descompensado. Em apenas um paciente foi necessária extensão da artrodese, incluindo a curva lombar. CONCLUSÕES: a descompensação grave do tronco com necessidade de segundo procedimento para artrodese lombar foi complicação não frequente nesta série de casos.