Usefulness of modified S-line for upper instrumented vertebra selection in adolescent idiopathic scoliosis Lenke type 1C curve.

PURPOSE: Determine the effect of using the modified S-line vertebra (MSLV) as the upper instrumented vertebra (UIV) on postoperative trunk balance, L4 tilt, and clinical outcomes in selective thoracic fusion (STF) for adolescent idiopathic scoliosis (AIS) Lenke type 1C curve. METHODS: Twenty-eight consecutive patients (all female; mean age: 15.4±2.0 years) with AIS Lenke type 1C curve were retrospectively enrolled. Primary outcome measures were coronal balance (absolute distance between C7 and the center of the sacral vertical line), L4 tilt, and Scoliosis Research Society (SRS)-22r scores at 2 years postoperatively. The group with the MSLV at the UIV was designated as the MSLV group (18 patients), and the group with the MSLV proximal (12 patients) or distal (4 patients) to the UIV was defined as the non-MSLV group. RESULTS: We observed no significant differences between the groups regarding age, LIV and stable vertebra positioning, or preoperative X-ray parameters. Postoperative coronal balance was significantly better in the MSLV group (0.39±0.08 vs. 1.34±0.22 cm; P.

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°.

Health-related Quality of Life (HRQOL) Outcomes of Selective/Nonselective Thoracic Fusion for Lenke 1C Adolescent Idiopathic Scoliosis (AIS) Patients with a Minimum 4-year Follow-up.

OBJECTIVE: Both the selective thoracic fusion (STF) and nonselective thoracic fusion (NSTF) are treatments for Lenke 1C adolescent idiopathic scoliosis (AIS). To date, the impacts of the two surgical strategies on patients' long-term quality of life remain unclear. Therefore, the purpose of this study was to explore the long-term effects of STF/NSTF on the quality of life in Lenke 1C AIS patients through a 4-10-year follow-up. METHODS: From January 2011 to April 2018, according to the inclusion and exclusion criteria, a retrospective single-center study of 75 surgical patients with Lenke 1C curves was performed (n = 75). They all underwent posterior fusion, and patients were divided into the selective thoracic fusion (STF) group (n = 42) and the nonselective thoracic fusion (NSTF) group (n = 33) based on their surgical approach. All participants received the survey of the visual analogue scale (VAS), SRS30, SF12, and Oswestry disability index (ODI) scales. Patients' gender, age, body mass index (BMI), surgical approach (STF/NSTF), surgical segments (UIV and LIV), follow-up time, complications, preoperative, postoperative, and last follow-up Cobb angles, and health-related quality of life (HRQOL) outcomes were collected, and analyzed through the Shapiro-Wilks test, Wilcoxon rank-sum test, t-test, and χ2 test. RESULTS: The mean follow-up of the entire cohort was 73 ± 5.6 months. The lumbar Cobb angle in the STF group improved from 31.8 ± 6.5° to 11.5 ± 5.1° after the operation and 10.3 ± 6.9° at the last follow-up. The postoperative correction rate of the lumbar curve was 63.8%, which increased to 67.7% at the last follow-up. In the NSTF group, the lumbar Cobb angle improved from 34.3 ± 11.3° to 4.3 ± 3.7° after the operation, and was 5.1 ± 3.1° at the last follow-up. The postoperative correction rate of the lumbar curve was 87.4%, and 85.1% at the last follow-up. At the last follow-up, the STF group had higher overall HRQOL scores than the NSTF group, and there were statistically differences between the different groups (STF/NSTF) in SRS-30-Mental health (p = 0.03), SRS-30-Satisfaction with management (p = 0.02), SRS-30-Pain (p = 0.03), ODI (p = 0.01), SF-12 PCS (p = 0.03), VAS back pain (p = 0.005) and VAS leg pain (p = 0.001). No statistically differences were found in SF12 MCS, SRS-30-Self-image/Appearance and SRS-30 Function/activity. CONCLUSION: After 4-10 years of follow-up, we found that the STF group achieved satisfactory correction results, and compared with the NSTF group, their overall HRQOL scores were higher, especially in terms of pain and satisfaction, where the STF group shows a significant advantage.

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.

Is it Safe to Save Levels and Choose the Lowest Instrumented Vertebra as Touched Vertebra While Selectively Fusing Lenke 1/2 Curves? A Proportional Meta-Analysis of Existing Evidence.

STUDY DESIGN: Meta-analysis. OBJECTIVE: To compare the clinical and radiological outcomes in patients with Adolescent Idiopathic scoliosis (AIS) treated by selective thoracic fusion (STF) with lowest instrumented vertebra (LIV) at touched vertebra (TV) vs stable vertebra (SV). METHODS: The databases PubMed, Embase and Google Scholar were searched until November 2020.Studies which had Lenke type 1 curves and Lenke type 2 curves in adolescent population treated by STF and which reported pre- and post-operative curve characteristics including correction percentage and complications were included. Studies which did not report the LIV selection, curve correction percentages and whose full text could not be acquired were excluded. RESULTS: Eight studies were included for analysis of which seven were found to be retrospective studies (level III evidence) and one was prospective study (level II evidence) each. Overall proportional meta-analysis found no significant difference in correction rate, total srs-22 scores, and complication rates. CONCLUSION: The evaluation of SV group and TV group as LIV for selective thoracic fusions in AIS reveals a comparable outcome in terms of curve correction, patient satisfaction scores and complication rates. The TV can be chosen safely as the LIV especially in type A and B Lenke 1&2 curves, as it saves more motion segments when compared to SV.

Is Lenke Rule About Selective Thoracic Fusion Applicable for Younger Adult Idiopathic Scoliosis Under 40 Years of Age: Comparison With Adolescent Patients.

STUDY DESIGN: Retrospective study. OBJECTIVE: To evaluate the surgical outcomes of younger adult idiopathic scoliosis patients (YAdIS) with selective thoracic fusion by comparing them with adolescent idiopathic scoliosis (AIS). METHODS: Seventy-two idiopathic scoliosis patients (36 adults and 36 adolescents) treated by posterior-only all-pedicle screw technique were retrospective reviewed and matched by fusion levels. Radiographic parameters were evaluated preoperatively, postoperatively, and at final follow-up. Operating time, blood loss, transfusion, and complications were noted. The clinical outcome was assessed by the Scoliosis Research Society-22 questionnaire (SRS-22). RESULTS: The major thoracic curves in YAdIS and AIS groups were 56.3° ± 9.7°, 53.3° ± 10.1° and corrected to 17.2° ± 7.3°, 14.9° ± 7.5° respectively without significant difference in correction rate (69.3% vs 72.0%). For the lumbar curve, Cobb angles in 2 groups were 35.6° ± 10.1°and 31.4 ± 9.2° preoperatively, and were spontaneously corrected to 18.5° ± 9.0° and 12.6° ± 8.2°.Correction rates were 48.0% and 59.8% (P < .05). Preoperative and postoperative coronal vertebra alignments (CVA) in the YAdIS group were 20.6 ± 9.7 mm and 16.8 ± 7.9 mm (P > .05), while in the AIS group was 17.8 ± 10.5 mm and 9.7 ± 8.3 mm (P < .05). However, sagittal parameters showed significant improvements in thoracic kyphosis in both groups (P < .05). Complication rates were 25% vs 11.1% (P = .13) with no significant difference. Preoperative SRS-22 was worse in the YAdIS group than AIS group. All the scores were significantly improved postoperatively in the YAdIS group. However, in the AIS group, only SRS scores improved significantly. CONCLUSIONS: YAdIS can also be treated very well with selective thoracic fusion based on the Lenke rule used for AIS.

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

STUDY DESIGN: Retrospective analysis of a prospectively collected data. OBJECTIVE: Lumbar flexibility(LF) is generally defined with preoperative side bending films;it is not clear what percentage of LF predicts the spontaneous lumbar curve correction (SLCC) at long term follow up. Aim of this study was to find out cut-off value of preoperative LF,apical vertebra rotation(AVR) and apical vertebral translation(AVT);which may predict more than 50%SLCC. METHODS: Patients with Lenke 1C&2C curves,treated with posterior STF,with a minimum 10 years follow up were included.The patients who had more than 50% SLCC(Group A) or less than 50% (Group B) were compared in terms of LF,AVR and AVT to understand a cut-off value of those parameters.Statistically, Receiver Operating Characteristic(ROC) test was used. RESULTS: Fifty five AIS patients (54F, 1M) with mean age 14 (11-17) were included to study.Thoracic curve correction rate was 75%;lumbar curve correction rate was 59% at the latest follow up.Group A included 45(82%) patients at the latest follow up.Three patients (5%) showed coronal decompensation at early postop and 2 of them became compensated at f/up.ROC analyses showed 69% flexibility as the cut-off value for SLCC (P < .01).The difference between groups in terms of preop mean AVRs was significant (P = .029) (Group A = 1.9; Group B = 2.4). CONCLUSION: In Lenke 1C&2C curves,whenever LF on the preoperative bending x-ray is greater than 70% (P < .01)and AVR is equal or less than grade 2,STF provides satisfactory clinical and radiological SLCC with more than mean 10 years f/up.This flexibility rate and apical vertebral rotation can be helpful in decision making for successful STF.

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

PURPOSE: Prior work identified optimal outcomes at 2 years following selective thoracic fusion (STF) for adolescent idiopathic scoliosis (AIS) but it is unclear whether these published predictors represent what is required to achieve an optimal outcome with further time and potential growth. The purpose of this study was to determine the preoperative factors associated with optimal outcome of STF for AIS at 5 years. METHODS: Patients with primary thoracic AIS (Lenke 1-4C curves) who underwent a STF and had minimum 5 years of follow-up were included. Optimal postoperative outcomes for a STF included a deformity-flexibility quotient (DFQ) < 4, lumbar curve < 26°, lumbar correction > 37%, C7-CSVL < 2 cm, lumbar prominence < 5°, and trunk shift < 1.5 cm. These outcomes were used to determine whether adhering to published recommendations for STF increased the likelihood of obtaining an optimal outcome at 5 years, which included: preoperative lumbar curve < 45°, lumbar bend < 25°, apical vertebral translation ratio > 1.2, and thoracic/thoracolumbar Cobb ratio > 1.2. RESULTS: 127 patients met inclusion. A preoperative lumbar curve < 45° was associated with an increased likelihood of achieving three of the optimal outcomes: DFQ < 4, lumbar curve < 26°, and lumbar prominence < 5°. Following the 25° bend rule resulted in two optimal outcomes, while Cobb ratio > 1.2 was only associated with one optimal outcome. AVT > 1.2 was not significantly associated with any optimal outcome measures. CONCLUSION: This study found that at 5 years, performing a STF when there is a preoperative lumbar Cobb < 45° remained the best guideline for increasing the likelihood of an optimal outcome.

Clinical, radiological and HRQoL outcomes after selective thoracic fusion with minimum 15-year follow-up.

INTRODUCTION: The purpose of the study was to provide a 15-year natural history evaluation of the radiographic appearance of uninstrumented compensatory lumbar curves in patients who had undergone selective thoracic fusion (STF) for scoliosis, measure any changes in health-related quality of life scores (HRQoL) and compare them with controls matched for age, gender and body-mass index (BMI). METHODS: STF group included 43 female adolescent idiopathic scoliosis (AIS) patients who underwent STF with mean age 33(27-42) years and a mean follow-up of 18.7 (15-28) years, mean BMI 22(18-29). Preop, early postop and follow-up radiographs were reviewed for behavior of lumbar curves. Control group included a random selection of healthy volunteers with no history of back pain and with mean age 33(27-41), and mean BMI 22(17-33). HRQoL scores were compared between two groups in latest f/up. Radiographs including low dose biplanar imaging with EOS were used to measure disc heights and assess for radiographic evidence of degenerative changes. Various parameters were statistically compared. RESULTS: Posterior fusion was performed in all 43, with all pedicle screws used in 41 and all-hook constructs in 2. Main thoracic curve correction was improved from pre-op to early-post-op and maintained at latest f/up (55.6°-16.1°-16.9°). Spontaneous lumbar curve correction (SLCC) was also maintained beyond 15 years (39.9°-16.6°-17.1°). Two patients developed coronal decompensation following surgery, but improved with time and were well compensated at final follow-up. Mean HRQoL scores, self-image and mental health scores were higher in STF group than control group (p < 0.05). SRS-22r pain and function, Oswestry Disability Index and Numeric Rating Scale, marital status, number of children were similar between the groups(p > 0.05). All disc heights except L5-S1 were significantly lower in STF group (p < 0.05). There was no significant difference between the groups for degenerative changes in the latest radiographs. CONCLUSION: In this group of patients, the uninstrumented lumbar curve spontaneously corrected and the correction was maintained after 18 years following surgery using STF. Mild degenerative changes were seen radiographically and HRQoL scores suggest that the psychological-functional well-being are quite good in the long term in AIS patients who have undergone STF when compared with an age-gender-BMI-matched population.

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.

Spinal Alignments of Residual Lumbar Curve Affect Disc Degeneration after Spinal Fusion in Patients with Adolescent Idiopathic Scoliosis: Follow-up after 5 or More Years.

INTRODUCTION: Despite preserving lumbar disc mobility, spinal sagittal, and/or coronal alignment might ultimately impede surgical success. The purpose of this study was to elucidate the effects of spinal alignment on lumbar disc degeneration after 5 or more years in adolescent idiopathic scoliosis (AIS) patients who underwent spinal fusion. METHODS: Subjects were 49 AIS patients who underwent posterior spinal fusion without lumbar curve fusion. The inclusion criteria were the following: 1) Lenke type 1A, 1B, 2A or 2B, 2) age 10 to 19 years at the time of operation, and 3) minimum 5-year follow-up. The exclusion criteria were the following: 1) diagnosed as other than AIS, 2) history of lumbar disc herniation and spondylolysis, 3) subsequent surgery, and 4) history of surgery before AIS surgery. Nineteen patients agreed to participate in this research. X-rays, lumbar MRI, and questionnaires were evaluated. Disc degeneration in non-fused segments was defined as Pfirrmann grade 3 or higher. Patients with disc degenerations at the final observation (DD[+] group) were compared to those without disc degenerations (DD[-] group). RESULTS: There were no significant differences in the preoperative or postoperative 1-week X-ray parameters between both groups. The lumbar curve was significantly larger in the DD[+] group compared with the DD[-] group at the final observation (DD[+]: 16.8 degrees, DD[-]: 10.4 degrees, p = 0.035). The sagittal vertical axis (SVA) was significantly larger in the DD[+] group compared with the DD[-] group at the final observation (DD[+]: -4.4 mm, DD[-]: -34.3 mm, p = 0.006). SRS-22 function, self-image, and satisfaction scores were lower in the DD [+] group compared with the DD[-] group at the final observation. CONCLUSIONS: The patients with DD had significantly larger lumbar curve and SVA with lower SRS-22 function, self-image, and satisfaction scores at the final observation. Even though the non-fused segments were preserved, spinal alignments of non-fused lumbar curve affect the DDs.

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.

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.

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.

Effect of Direct Vertebral Rotation in Single Thoracic Adolescent Idiopathic Scoliosis: Better 3-Dimensional Deformity Correction.

OBJECTIVE: To analyze the effects of direct vertebral rotation (DVR) on radiologic outcomes in the treatment of thoracic adolescent idiopathic scoliosis after selective thoracic fusion with pedicle screw instrumentation. METHODS: Adolescent idiopathic scoliosis patients with single thoracic curves (n = 110) treated by selective thoracic fusion with a minimum of 2 years of follow-up were retrospectively analyzed. The patients were separated into 2 groups: non-DVR (n = 63) and DVR (n = 47). RESULTS: There was a significant difference in fused segments between the non-DVR and DVR groups (P < 0.001). There was also a significant difference in main thoracic curve postoperatively (P = 0.001) and at the last follow-up (P = 0.006) between the non-DVR and DVR groups. However, there was no significant difference in proximal thoracic and lumbar curves postoperatively (proximal thoracic curve: P = 0.186; lumbar curve: P = 0.155) and at the last follow-up (proximal thoracic curve: P = 0.250; lumbar curve: P = 0.060) between the 2 groups. Significant improvements in the lowest instrumented vertebra tilt and disc angle were noted but then slight deteriorations in such were observed during the follow-up period in the non-DVR group. The prevalence of unsatisfactory results was 20.6% (13 of 63) in the non-DVR group and 19.1% (9 of 47) in the DVR group, with no significant difference (P = 0.522). CONCLUSIONS: For correcting single thoracic adolescent idiopathic scoliosis by selective thoracic fusion with pedicle screw instrumentation, the addition of DVR to the surgical procedure showed comparable radiologic outcomes compared with non-DVR procedures.

Selective thoracic fusion for adolescent thoracic scoliosis secondary to Chiari I malformation: a comparison between the left and the right curves.

PURPOSE: The aim of this study was to compare the clinical outcomes of selective thoracic fusion in the surgical treatment of Chiari malformation type I (CMI) adolescents with different curve patterns. METHODS: Sixty-three CMI patients with left thoracic curve (LTC) and 63 age- and curve-magnitude-matched CMI patients with right thoracic curve (RTC) were recruited. Selective thoracic fusion was performed for two groups. The coronal and sagittal parameters including the thoracic and lumbar Cobb angle, apical vertebral translation, trunk shift, thoracic kyphosis (TK), lumbar lordosis and sagittal vertical axis were measured before surgery, immediately postoperative and at the final follow-up. The accuracy of pedicle screw placement between both groups was also compared. RESULTS: All preoperative radiographic parameters were matched in both groups except for TK (LTC group 40.1° vs. RTC group 23.0°, P = 0.021). The immediately postoperative spontaneous correction of the lumbar curve was 56.9% in LTC group, which was remarkably lower than in RTC patients (67.9%). Patients with LTC were found to have obviously increased trunk shift than those with RTC (15.1 mm vs. 8.0 mm, P = 0.038). At the final follow-up, the correction of the thoracic curve was comparable between the two groups (59.9% vs. 62.6%, P = 0.610). The rate of the pedicle screw perforations was similar between both groups. CONCLUSIONS: Patients with LTC and RTC can both be successfully corrected through selective thoracic fusion with a promising long-term surgical outcome. CMI patients with RTC tend to have a better spontaneous correction of the lumbar curve after surgery. These slides can be retrieved under Electronic Supplementary Material.

Selective Thoracic Fusion for Adolescent Idiopathic Scoliosis: Long-Term Radiographic and Functional Outcomes.

INTRODUCTION: Selective thoracic fusions (STFs) were introduced by Moe to treat the structural thoracic curve when a more flexible lumbar component existed. It is unknown how the curves behave and how the patients function beyond 20 years after surgery. METHODS: Of the 152 eligible patients with STF, 67 were traced and contacted and 40 completed outcome questionnaires (Oswestry Disability index [ODI], Scoliosis Research Society-30 [SRS-30]) and had follow-up standing radiographs. The preoperative, postoperative, 1-year, and follow-up films were compared, and the lumbar spine on follow-up assessed for signs of degeneration-disc space narrowing, osteophyte formation, rotatory subluxation, and lateral spondylolisthesis. RESULTS: The average follow-up was 32.7 years. There were 27 Lenke 1C, 10 Lenke 2C, and 3 Lenke 1B curves. A posterior fusion was performed in 37, with a Harrington rod used in 28 and all-hook constructs in 12 with fusion to T10 (1), T11 (10), T12 (22), or L1 (7). The average preoperative right thoracic curves were 56.1°, 36.2° 1 year postoperation, and 38.6° at follow-up. The average preoperative lumbar curve was 44.6°, being 35.2° at 1 year postoperation, and 36.9° at follow-up. Five patients had additional surgery, 3 pseudarthrosis repairs (one with extension of the fusion to L4), 1 implant removal, and 1 microdiscectomy 35 years postoperatively. At follow-up, the average ODI was 8.7 (0-62) and the average SRS-30 3.8 (1.4-4.9). Nine patients took nonnarcotic medication, usually weekly or less, with only one taking daily narcotics. The most common lumbar radiographic finding was disc space narrowing at the apex of the lumbar curve, and osteophytes at L2-L3. There was no correlation of the lumbar changes to ODI, with a tendency to more medication use with longer follow-up (older subjects). CONCLUSION: At an average 33-year follow-up, the lumbar curve in STF is unchanged, with patients functioning well and mild radiographic changes in the lumbar spine.

Postoperative changes in sagittal spinopelvic alignment in sitting position in adolescents with idiopathic thoracic scoliosis treated with posterior fusion: an initial analysis.

OBJECTIVE Previous studies have reported spinal straightening and pelvic retroversion when changing from erect to sitting posture in patients with adolescent idiopathic scoliosis (AIS), which were thought to be related to low-back pain after sitting for long periods. However, the sitting sagittal alignment after posterior spinal fusion has not been evaluated. This study aims to assess the influence of posterior fusion surgery upon sitting sagittal spinopelvic alignment in adolescents with idiopathic thoracic curves (thoracic AIS [T-AIS]). METHODS A total of 44 T-AIS patients (30 Lenke I and 14 Lenke II) from the authors' center were included in this study. Preoperative and postoperative long-cassette lateral radiographs of the spine and pelvis were obtained with the patients in standing and sitting positions. Thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were measured on standing and sitting lateral radiographs. Patients were divided into selective thoracic fusion (STF) and nonselective thoracic fusion (NSTF) groups. RESULTS At baseline, TK, LL, and SS decreased by 27.5%, 42.1%, and 31.1%, respectively, from the standing to the sitting position, while PT increased by 193.6%. After posterior spinal fusion, increased TK, LL, and SS and corresponding decreased PT were observed compared to baseline parameters in the sitting position. Comparison of postoperative sitting and standing values for the whole cohort showed that the mean LS and SS values were significantly lower in the sitting position (decreased by 14.0% and 13.9%, respectively, compared to standing), whereas the mean PT value was significantly greater (increased by 39.0%, compared to standing). Similar changes were also observed in the STF group: postoperatively the mean LL value was 15.6% lower in sitting than in standing, while the mean SS value was 11.5% lower. However, no obvious changes of the postoperative values in sitting were found in the NSTF group. CONCLUSIONS Nonselective thoracic fusion surgery in T-AIS patients diminished spinal straightening and pelvic retroversion during sitting. Reducing distal fusion levels was of special value in not only saving more lumbar mobility, but also preserving the function of pelvic posterior rotation.

The Lumbar Gap Measurement in Lenke 1-4C Curves.

STUDY DESIGN: Retrospective review. OBJECTIVES: To assess whether the lumbar gap (LG) measurement, which is the distance between the center sacral vertical line and the concave edge of the apical vertebra of the lumbar curve, would be a useful tool to predict the need for lumbar curve fusion in the Lenke 1-4C curves. SUMMARY OF BACKGROUND DATA: The current treatment guidelines of selective thoracic fusion in the Lenke 1-4C curves are not routinely accepted. METHODS: One hundred three adolescent idiopathic scoliosis (AIS) patients had undergone either selective thoracic fusion (STF) or both thoracic and lumbar curves fusion (TLF) for Lenke 1-4C curves. The correlations between the fusion decision making and preoperative LG, coronal balance, thoracic and lumbar Cobb, apical vertebra translation, and rotation were analyzed. The radiographic outcomes and SRS-30 of a minimum 2-year follow-up were reviewed in each group. RESULTS: A total of 51 patients (49.5%) underwent an STF, and 52 patients (50.5%) underwent a TLF. The mean LG was 22.0 ± 8.8 mm in the TLF, which was 2.3 times greater than the STF (9.6 ± 3.9 mm) (p < .0001). Only 5% of the lumbar curves were fused when the LG was 10 mm or less. Ninety percent of the lumbar curves were fused when the LG was 16 mm or greater, and 100% lumbar curves were fused with an LG of 21 mm or greater. The preoperative coronal imbalance to the left in the TLF was significantly greater than the STF. A mean 47% thoracic correction corresponded to a mean 39% spontaneous correction of the lumbar curve obtained in the SFT, which was significantly different from the TLF (56% and 65%). There were no differences in the SRS-30 scores at 2 years postoperatively between the STF and the TLF. CONCLUSION: The lumbar curve should not be fused when the LG was 10 mm or less, and very likely should be fused when the LG exceeds 20 mm in the Lenke 1-4C AIS patients. LEVEL OF EVIDENCE: Level III.

Radiological and clinical outcome of selective thoracic fusion for patients with Lenke 1C and 2C adolescent idiopathic scoliosis with a minimum follow-up of 2 years.

BACKGROUND CONTEXT: In Lenke 1C and 2C curves, the choice between selective thoracic fusion (STF) versus non-selective thoracic fusion as the optimal surgical treatment is controversial. OBJECTIVE: This study aimed to assess the radiological and clinical outcome of patients with Lenke 1C and 2C curves treated with STF. STUDY DESIGN: This is a retrospective study. PATIENT SAMPLE: A total of 44 patients comprised the study sample. METHODS: Forty-four patients with Lenke 1C and 2C curves with adolescent idiopathic scoliosis who underwent STF were reviewed. Radiological parameters and Scoliosis Research Society (SRS)-22r scores were assessed preoperatively, postoperatively, and on final follow-up. The incidence of coronal decompensation, lumbar decompensation, and adding-on phenomenon were reported. RESULTS: Mean follow-up duration was 45.1±12.3 months and mean age was 17.0±5.1 years. The preoperative middle thoracic and thoracolumbar/lumbar (MT:TL/L) Cobb angle ratio was 1.4±0.3 and the MT:TL/L apical vertebra translation (AVT) ratio was 1.6±0.8. Final follow-up coronal balance was -13.0±11.5 mm, main thoracic AVT was 6.9±11.8 mm, and lumbar AVT was -20.4±13.8 mm (p<.05). Lumbar Cobb angle improved from 47.5°±7.8° to 24.9°±8.2° after operation and 23.3°±9.8° at final follow-up. The spontaneous lumbar curve correction rate was 50.9%. There were 9 patients (20.5%) who had coronal decompensation, 4 patients (9.1%) who had lumbar decompensation, and 11 patients (25.0%) who had adding-on phenomenon. We did not perform any revision surgery. The SRS-22r scores improved significantly in the overall scores, self-image, and mental health domain. CONCLUSIONS: Selective thoracic fusion led to improvement in the radiological and clinical outcome for patients with Lenke 1C and 2C. Although no patients required revision surgery, the rate of coronal decompensation, lumbar decompensation, and adding-on phenomenon are significant.