Higher Flexibility and Better Immediate Spontaneous Correction May Not Gain Better Results for Nonstructural Thoracic Curve in Lenke 5C AIS Patients: Risk Factors for Its Correction Loss

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.

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

STUDY DESIGN

Retrospective study.

PURPOSE

The upper end vertebra (UEV) is often selected as the upper instrumented vertebra (UIV) in patients with adolescent idiopathic scoliosis (AIS) with Lenke type 5C curves; however, the effect of adjusting UIV selection one level toward the cranial side (UEV + 1) is unknown. Therefore, this study aimed to assess the effect of UIV extension on scoliosis correction and global alignment in patients with the UIV as the UEV and UEV + 1.

METHODS

Data of 52 patients with AIS with Lenke type 5C curves who underwent selective thoracolumbar/lumbar (TL/L) fusion with a minimum follow-up period of 2 years were retrospectively analyzed. The patients were divided according to the UIV in relation to the UEV: the UEV and UEV + 1 groups. Radiographic parameters and clinical outcomes were compared between the two groups.

RESULTS

Among the 52 patients, 24 and 28 were included in the UEV and UEV + 1 group. Baseline data showed no intergroup differences except for the UIV level. While the UEV + 1 group showed a significantly greater TL/L curve correction (72.9% vs. 62.8%, p < 0.05) and a lower UIV tilt, it showed a significantly greater absolute value of radiographic shoulder height (RSH) (- 7.9 vs. - 0.9 mm, p < 0.05) and coronal balance (- 11.0 mm vs - 4.8 mm, p < 0.05) at 2 years postoperatively. The rate of post-operative shoulder imbalance (RSH ≥ 2 cm) was significantly higher in the UEV + 1 than in the UEV group. No intergroup differences were observed in the sagittal alignment and patient outcomes between the two groups.

CONCLUSION

When the UIV was selected as the UEV + 1, correction of the TL/L curve improved; however, it increased the risk of shoulder and coronal imbalance. There is no clinical benefit observed in terms of extending the UIV to the UEV + 1; therefore, the UIV should be selected as the UEV to maintain harmonious global alignment.

LEVEL OF EVIDENCE

Level 3.

Long-Term Follow-up of Posterior Selective Thoracolumbar/Lumbar Fusion in Patients With Lenke 5C Adolescent Idiopathic Scoliosis: An Analysis of 10-Year Outcomes

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of this study was to assess long-term radiographic and clinical outcomes in Lenke 5C adolescent idiopathic scoliosis (AIS) patients after posterior selective fusion.

METHODS

Lenke 5C AIS patients who underwent posterior selective thoracolumbar/lumbar (TL/L) fusion in our hospital from January 2007 to January 2010 were recruited. Radiographic parameters were measured preoperatively and at the 3-month, 1-year, 2-year, 5-year, and 10-year follow-ups. The SRS-22 (Scoliosis Research Society) questionnaire was used to assess the clinical outcomes.

RESULTS

We included 37 patients who underwent posterior selective TL/L fusion surgery in our study, and the mean follow-up time was 11.26 ± 0.85 years. The average preoperative Cobb angles of the thoracic and TL/L curves were 24.0 ± 9.0° and 45.4 ± 6.3°, respectively, which were corrected to 12.2° and 12.4° at the 3-month follow-up postoperatively, with correction losses of 2.2° and 1.5° at the 10-year follow-up. In the sagittal plane, the degree of thoracic kyphosis (TK) gradually increased over the follow-up period. The proximal junctional angle (PJA) also gradually increased from 6.7 ± 4.6 to 13.7 ± 5.6 during the follow-up period. For the clinical outcomes, correction surgery improved the SRS-22 scores in each domain, especially in the self-image domain.

CONCLUSIONS

Posterior selective TL/L fusion can effectively correct spinal deformities, leading to stable outcomes for 10 years postoperatively. During the follow-up period, the degree of TK presented an increasing trend that remained almost constant after the 1-year follow-up. Moreover, the variation in the PJA was highly significant in the postoperative period, and it showed an increasing trend until the 2-year follow-up.

Preoperative pelvic obliquity: possible relation to postoperative coronal decompensation in thoracolumbar/lumbar adolescent idiopathic scoliosis

OBJECTIVE

Pelvic obliquity is frequently observed in patients with adolescent idiopathic scoliosis with thoracolumbar/lumbar (TL/L) curve. This study aimed to assess pelvic obliquity changes and their effects on clinical outcomes of posterior fusion surgery.

METHODS

Data in 80 patients (69 with type 5C and 11 with type 6C adolescent idiopathic scoliosis) who underwent posterior fusion surgery were retrospectively analyzed. Pelvic obliquity was defined as an absolute pelvic obliquity angle (POA) value of ≥ 3°. The patients were divided into groups according to preoperative pelvic obliquity. Moreover, patients with preoperative pelvic obliquity were divided based on POA change from preoperative values versus 2 years postoperatively. Patients were divided based on the presence of selective or nonselective TL/L fusion. Radiographic parameters and clinical outcomes were compared between these groups.

RESULTS

Among 80 patients, 41 (51%) showed preoperative pelvic obliquity, and its direction was upward to the right for all cases. Coronal decompensation 2 years postoperatively was significantly elevated in patients with preoperative pelvic obliquity (p < 0.05). Thirty-two patients (40%) displayed pelvic obliquity 2 years postoperatively. Among 41 patients with preoperative pelvic obliquity, 22 patients (54%) were in the group with a decrease in POA, and 19 were in the group with no decrease. The group with no decrease in POA showed significant TL/L curve progression throughout the postoperative follow-up period. The patients with nonselective fusion showed a significantly lower incidence of pelvic obliquity at 2 years postoperatively.

CONCLUSIONS

Postoperative coronal decompensation more frequently occurred in patients with preoperative pelvic obliquity than in those without pelvic obliquity preoperatively. In addition, postoperative pelvic obliquity changes may be related to residual lumbar curve behavior.

Anterior Selective Lumbar Fusion Saving More Distal Fusion Segments Compared with Posterior Approach in the Treatment of Adolescent Idiopathic Scoliosis with Lenke Type 5: A Cohort Study with More Than 8-Year Follow-up

Objective

To investigate whether anterior selective fusion (ASF) could save more distal fusion segments compared with posterior approach in the treatment of Lenke type 5 adolescent idiopathic scoliosis with long term follow‐up.

Methods

A retrospective cohort study. From 2008 to 2011, 22 AIS girls with Lenke type 5 who underwent ASF or posterior selective fusion (PSF) with more than 8‐year follow‐up, were extracted from the database. 13 girls in the ASF group had an average age of 14.3 ± 1.3 years and Risser sign of 3.3 ± 1.1; 9 PSF girls had an average age of 16.2 ± 3.6 years and Risser sign of 3.8 ± 1.5. The radiographic outcome was compared between groups preoperatively, 6‐month postoperatively, 8‐year postoperatively and at last follow‐up (>8 years).

Results

The average follow‐up duration was 8.7 ± 0.4 (ASF) and 8.8 ± 0.5 (PSF) years, respectively. There was no significant difference at baseline in age, Risser sign and preoperative curve pattern in the coronal and sagittal plane between the groups (P > 0.05). The ASF group had significantly shorter fusion segments (5.1 ± 0.6 vs. 7.0 ± 1.3) and decreased upper instrumented vertebra (UIV) (T₁₁ ± 0.8 vs. T₁₀ ± 0.8) than the PSF (P < 0.05); while no significant difference was found in the lower instrumented vertebra (LIV) and distal reserved segments (P > 0.05), which suggested that ASF could shorten the fusion segments by lowering UIV. The distal compensatory curve in the ASF group (9.0° ± 3.9°) was significantly larger than in the PSF group (3.3° ± 2.4°, P = 0.003), despite of no significant difference in the incidence of coronal imbalance (P > 0.05), indicating that both two approaches could obtain satisfactory correction in the coronal plane. In the sagittal plane, PSF patients had significantly larger lumbar lordosis (LL, 59.1° ± 10.5°), thoracic kyphosis (TK, 37.2° ± 13.3°) and proximal junctional angle (PJA, 13.3° ± 6.1°) at the last follow‐up than the ASF (LL: 43.4° ± 9.4°; TK: 20.7° ± 8.4°; PJA: 4.7° ± 3.4°; P < 0.05), but without significant difference in proximal junctional kyphosis (PJK) and sagittal vertical axis (SVA) (P > 0.05). After controlling for age, Risser sign, and radiographic parameters related to the primary curve pattern, shorter fusion segments and more distal reserved segments still remained significant in the ASF group with greater Risser sign (P < 0.05). No major intra‐ or post‐operative complications occurred.

Conclusions

Both ASF and PSF could obtain satisfactory coronal and sagittal correction for Lenke 5 AIS; compared with PSF, ASF could shorten the fusion segments by lowering UIV, and save more distal fusion segments only in patients with greater skeletal maturity.

Should L3 be selected as the lowest instrumented vertebra in patients with Lenke type 5C adolescent idiopathic scoliosis whose lowest end vertebra is L4?

OBJECTIVE

L3 is most often selected as the lowest instrumented vertebra (LIV) to conserve mobile segments in fusion surgery; however, in cases with the lowest end vertebra (LEV) at L4, LIV selection as L3 could have a potential risk of correction loss and coronal decompensation. This study aimed to compare the clinical and radiographic outcomes depending on the LEV in adolescent idiopathic scoliosis (AIS) patients with Lenke type 5C curves.

METHODS

Data from 49 AIS patients with Lenke type 5C curves who underwent selective thoracolumbar/lumbar (TL/L) fusion to L3 as the LIV were retrospectively analyzed. The patients were classified according to their LEVs into L3 and L4 groups. In the L4 group, subanalysis was performed according to the upper instrumented vertebra (UIV) level toward the upper end vertebra (UEV and 1 level above the UEV [UEV+1] subgroups). Radiographic parameters and clinical outcomes were compared between these groups.

RESULTS

Among 49 patients, 32 and 17 were in the L3 and L4 groups, respectively. The L4 group showed a lower TL/L curve correction rate and a higher subjacent disc angle postoperatively than the L3 group. Although no intergroup difference was observed in coronal balance (CB), the L4 group showed a significantly higher main thoracic (MT) and TL/L curve progression during the postoperative follow-up period than the L3 group. In the L4 group, the UEV+1 subgroup showed a higher absolute value of CB at 2 years than the UEV subgroup.

CONCLUSIONS

In Lenke type 5C AIS patients with posterior selective TL/L fusion to L3 as the LIV, patients with their LEVs at L4 showed postoperative MT and TL/L curve progression; however, no significant differences were observed in global alignment and clinical outcome.

Preoperative Thoracic Curve Magnitude and L4 End Vertebra Were Risk Factors for Subjacent Disc Wedging After Selective Thoracolumbar/Lumbar Fusion with L3 as the Lowest Instrumented Vertebra in Lenke Type 5 Curve Patients

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVE

This study aimed to investigate the incidence and risk factors of subjacent disc wedging (SDW) in adolescent idiopathic scoliosis (AIS) patients with Lenke type 5 curve.

SUMMARY OF BACKGROUND DATA

SDW is frequently observed after surgery; however, data about its mechanism and relations with outcome are limited.

METHODS

Data of 59 patients with AIS with Lenke type 5 curves who underwent posterior spinal fusion to L3 as the lowest instrumented vertebra (LIV) were retrospectively analyzed. The subjacent disc angle (SDA) was defined as the angle between L3 (LIV) and L4. SDW was defined as the absolute value of SDA of 10° or higher 2 years postoperatively. The incidence of SDW was investigated between nonselective and selective thoracolumbar/lumbar (TL/L) fusion group. In the selective group, patients with and without SDW were compared.

RESULTS

Among 59 patients, 11 had nonselective and 48 had selective fusion. No patients in the nonselective group showed SDW versus 13 patients in the selective group (27%) showed SDW. In the selective group, patients with SDW showed significantly greater main thoracic curve, apical vertebral translation of the main thoracic curve, upper instrumented vertebra tilt, LIV tilt, and SDA 2 years postoperatively, whereas no differences were found in the coronal balance or clinical outcome. Multivariate analysis revealed preoperative T curve and SDA as predictors of SDW occurrence. T curve greater than 30° and SDA greater than 0° were calculated as cutoff values based on the receiver operating characteristic curve.

CONCLUSION

SDW is sometimes seen in Lenke type 5 patients with AIS who underwent selective TL/L fusion. SDW seemed to occur as a compensation mechanism for progressing deformity of unfused segments (thoracic curve and residual lumbar curve) to maintain coronal alignment. Preoperative T curve > 30° and SDA > 0° (lower-end vertebra as L4) were determined as risk factors for SDW occurrence.Level of Evidence: 3.

What determines immediate postoperative coronal balance and delayed global coronal balance after anterior spinal fusion for Lenke 5C curves?

PURPOSE

To determine the factors associated with 6-week postoperative global coronal balance and delayed global coronal balance at 2-year follow-up after anterior spinal fusion for Lenke 5C curves.

METHODS

A total of 124 consecutive Lenke 5C curves with minimum 2-year follow-up was studied. Radiographic parameters were studied preoperatively, 6 weeks postoperatively, and 2 years postoperatively. Coronal balance was measured by C7-CSVL and trunk shift < 20 mm. The study outcomes were patients with early coronal balance and those who had immediate imbalance but developed delayed balance. Multivariate regression analyses of associated factors were performed with cutoffs determined by receiver operating characteristic curve.

RESULTS

31.5% patients attained global coronal balance immediate postoperatively and 89.4% of the early imbalance cases showed spontaneous coronal balance at 2-year follow-up. Increased preoperative UIV tilt (OR 1.093; p = 0.026; 95% CI: 1.011-1.182) and reduced immediate postoperative RSH difference (OR 0.963; p = 0.015; 95% CI: 0.935-0.993) were associated with immediate postoperative balance. For those with immediate imbalance, larger preoperative major Cobb angle (OR 1.226; p = 0.047; 95% CI: 1.003-1.499), less preoperative C7-CSVL (OR 0.829; p = 0.016; 95% CI: 0.712-0.966), and less immediate postoperative LIV tilt (OR 0.728; p = 0.013; 95% CI: 0.567-0.934) were associated with 2-year coronal balance. There was significant improvement in function (p = 0.006), self-image (p = 0.039) and total score domains (p = 0.014) in immediate imbalance to 2-year balance and imbalance groups.

CONCLUSION

Successful balance is achieved with a parallel fusion mass when performing anterior spinal fusion for Lenke 5C curves. Patients should be reassured that most attain eventual coronal balance despite the early imbalance. Level of evidence Therapeutic III.

Upper instrumented vertebra to the right of the lowest instrumented vertebra as a predictor of an increase in the main thoracic curve after selective posterior fusion for the thoracolumbar/lumbar curve in Lenke type 5C adolescent idiopathic scoliosis: multicenter study on the relationship between fusion area and surgical outcome

OBJECTIVE

Unfused main thoracic (MT) curvatures occasionally increase after selective thoracolumbar/lumbar (TL/L) fusion. This study sought to identify the predictors of an unacceptable increase in MT curve (UIMT) after selective posterior fusion (SPF) of the TL/L curve in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS).

METHODS

Forty-eight consecutive patients (44 females and 4 males, mean age 15.7 ± 2.5 years, range 13-24 years) with Lenke type 5C AIS who underwent SPF of the TL/L curve were analyzed. The novel "Shinshu line" (S-line) was defined as a line connecting the centers of the concave-side pedicles of the upper instrumented vertebra (UIV) and lowest instrumented vertebra (LIV) on preoperative radiographs. The authors established an S-line tilt to the right as S-line positive (S-line+, i.e., the UIV being to the right of the LIV) and compared S-line+ and S-line- groups for thoracic apical vertebral translation (T-AVT) and MT Cobb angle preoperatively, early postoperatively, and at final follow-up. The predictors for T-AVT > 20 mm at final follow-up were evaluated as well. T-AVT > 20 mm was defined as a UIMT.

RESULTS

Among the 48 consecutively treated patients, 26 were S-line+ and 22 were S-line-. At preoperative, early postoperative, and final follow-up a minimum of 2 years later, the mean T-AVT was 12.8 mm (range -9.3 to 32.8 mm), 19.6 mm (range -13.0 to 41.0 mm), and 22.8 mm (range -1.9 to 68.7 mm) in the S-line+ group, and 10.8 mm (range -5.1 to 27.3 mm), 16.2 mm (range -11.7 to 42.1 mm), and 11.0 mm (range -6.3 to 26.9 mm) in the S-line- group, respectively. T-AVT in S-line+ patients was significantly larger than that in S-line- patients at the final follow-up. Multivariate analysis revealed S-line+ (odds ratio [OR] 23.8, p = 0.003) and preoperative MT Cobb angle (OR 7.9, p = 0.001) to be predictors of a UIMT.

CONCLUSIONS

S-line+ was defined as the UIV being to the right of the LIV. T-AVT in the S-line+ group was significantly larger than in the S-line- group at the final follow-up. S-line+ status and larger preoperative MT Cobb angle were independent predictors of a UIMT after SPF for the TL/L curve in patients with Lenke type 5C AIS. Surgeons should consider changing the UIV and/or LIV in patients exhibiting S-line+ during preoperative planning to avoid a possible increase in MT curve and revision surgery.

Modified PUMC classification for adolescent idiopathic scoliosis

BACKGROUND

The original Peking Union Medical College (PUMC) classification of adolescent idiopathic scoliosis (AIS) is one system to combine each type with corresponding surgical fusion guidance, presenting comparable interobserver reliability, and reproducibility with Lenke classification. However, during its application in previous over 10 years, we found 2 main problems of this classification, which required modification.

PURPOSE

(1) To evaluate the interobserver and intraobserver reliability, (2) to assess the effects of the added fusion criteria of proximal thoracic (PT) curve on improving postoperative shoulder balance of the modified PUMC classification of AIS.

STUDY DESIGN/SETTING

Retrospective analysis of our AIS cohort and prospective validation of its effectiveness.

PATIENT SAMPLE

Fifty sets of preoperative radiographs of AIS patients were randomly chosen from our AIS database. Furthermore, 46 consecutive AIS cases with PT curve were enrolled who underwent surgeries in our center from July 2007 to July 2013, with at least 2-year follow-up.

OUTCOME MEASURES

The classification results of 50 sets of preoperative radiographs by 5 surgeons. The shoulder balance was evaluated using radiographic shoulder height.

METHODS

Five surgeons independently evaluated and classified presurgical radiographs of 50 AIS patients based on the modified PUMC classification. Inter- and intraobserver reliabilities were calculated. Furthermore, the post-op shoulder balance was investigated in 46 consecutive cases of AIS with PT curve who were treated strictly based on the modified PUMC classification.

RESULTS

The Kappa coefficients of inter- and intraobserver reliability of the overall modified PUMC classification are 0.889 and 0.865, respectively. The Kappa coefficients of inter- and intraobserver reliability for the type II are 0.791 and 0.746, respectively. In addition, the shoulder balance rate of the 46 AIS patients with PT curve at the final follow-up was 95.7%.

CONCLUSIONS

Modified PUMC classification presents incremental improvement compared to our original published version, with high interobserver and intraobserver reliability and better performance of postoperative shoulder balance. Furthermore, the modified PUMC classification provides corresponding surgical fusion guidance for each subtype. Multicenter prospective studies with larger samples are still needed to further improve this system.

Surgical Treatment of Lenke Type 5 Adolescent Idiopathic Scoliosis: A Systematic Review

STUDY DESIGN

A systematic review.

OBJECTIVE

To systemically review the previous literature regarding surgical treatment of Lenke type 5 adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The Lenke classification was published in 2001 as the classification of AIS. Since then, numerous articles have been published reporting the outcomes of surgical treatment of Lenke type 5 AIS.

METHODS

The electronic databases PubMed, EMBASE, and Web of Science were queried up to Aug 2018 for articles regarding surgical treatment of Lenke type 5 AIS. Surgical variables, radiographic assessments, and clinical outcomes of surgical treatment of Lenke type 5 AIS were summarized.

RESULTS

Fifty studies met the inclusion criteria. The average fused levels, % correction of thoracolumbar/lumbar curve at final follow-up, and % correction of thoracic curve at final follow-up for anterior and posterior procedures were reported to be 3.6-5.3 and 4.3-7.8 levels, 53-86 and 55-94% and 17-52 and 19-67%, respectively. Average coronal balance was imbalanced (≥20 mm) at preoperation in 22/43 reporting study groups and balanced (<20 mm) at final follow-up in all 37 reporting study groups. Scoliosis Research Society Version 22 scores showed no difference between anterior and posterior procedures in most of the reporting studies (5/6).

CONCLUSION

Overall, the outcomes of surgical treatment of Lenke type 5 AIS are excellent. The thoracic curve was spontaneously corrected after surgery and coronal balance after surgery was better than before surgery. Both anterior and posterior procedures demonstrated satisfactory outcomes.

LEVEL OF EVIDENCE

4.

Comparison of Extending Fusion to Thoracic Curve Versus Thoracolumbar/Lumbar Fusion in Posterior Fusion of Patients with Lenke 5C: Variation in Upper End Vertebrae Tilt Affected Coronal Balance

BACKGROUND

Extended fusion can be performed in patients with Lenke 5C adolescent idiopathic scoliosis (AIS) with a large and relatively rigid thoracic curve. Progression of the thoracic curve is related to coronal imbalance. We aimed to determine the correlation between the upper instrumented vertebra choice and coronal balance in patients with Lenke 5C AIS.

METHODS

A total of 61 patients with Lenke 5C AIS underwent posterior fusion from 2009 to 2015 in a single institution with ≥2 years of follow-up data available. The extended fusion group (n = 32) and thoracolumbar/lumbar (TL/L) fusion group (n = 29) were compared for the correction rates for the main TL/L and thoracic curves, coronal balance, upper end vertebra (UEV) tilt, and Scoliosis Research Society-22 questionnaire score.

RESULTS

Both groups had excellent correction of the main TL/L curve, and the extended fusion group had a significantly greater correction rate of the thoracic curve than the TL/L fusion group (70.2% vs. 57.3%). The incidence of coronal imbalance was similar in both groups. The spontaneous change in UEV tilt was associated with the change in coronal balance from the first to the final follow-up examination. In the TL/L fusion group, the increase in UEV tilt from the first to final follow-up visit resulted in improved coronal balance at the final follow-up examination. Both groups had similar Scoliosis Research Society-22 questionnaire scores at 2 years postoperatively.

CONCLUSIONS

In patients with Lenke 5C AIS, thoracic curve fusion results in better correction of the thoracic curve but no improvement in coronal balance. With TL/L fusion, a postoperative UEV tilt >5° leads to better coronal balance.

Spontaneous correction of coronal imbalance after selective thoracolumbar-lumbar fusion in patients with Lenke-5C adolescent idiopathic scoliosis

BACKGROUND CONTEXT

Coronal imbalance is a complication of corrective surgeries in adolescent idiopathic scoliosis (AIS). However, few studies about immediate coronal decompensation in Lenke-5C curves have reported its incidence, prognosis, and related factors.

PURPOSE

To evaluate the development of coronal imbalance after selective thoracolumbar-lumbar (TL/L) fusion (SLF) in Lenke-5C AIS, and to reveal related factors.

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

This study included 50 consecutive patients with Lenke-5C AIS who underwent SLF at a single center.

OUTCOME MEASURES

Whole-spine anteroposterior and lateral radiographs were used to measure radiological parameters.

METHODS

Patients were divided into two groups according to the presence or absence of coronal imbalance (distance between C7 plumb line and central sacral vertical line >2 cm) in the early (1 month) postoperative period. Various radiological parameters were statistically compared between groups.

RESULTS

Of the patients, 28% (14 of 50) showed coronal imbalance in the early postoperative period; however, most of them (13 of 14) showed spontaneous correction during follow-up. The development of coronal imbalance was related to less flexibility of the TL/L curve (51.3% vs. 52.6%, p=.040), greater T10-L2 kyphosis (11.7° vs. 6.4°, p=.034), and greater distal junctional angle (6.0° vs. 3.7°, p=.025) in preoperative radiographs. Lowermost instrumented vertebra (LIV) tilt was greater in the decompensation [+] group in the early postoperative period (8.8° vs. 4.4°, p=.009). However, this difference disappeared in final follow-up with the decrease of LIV tilt in the decompensation [+] group.

CONCLUSIONS

Less flexibility of the TL/L curve, greater TL kyphosis, and greater distal junctional angle preoperatively were predictive factors for immediate coronal imbalance in Lenke-5C curves. Although coronal imbalance was frequently detected in the early postoperative period after SLF, it was mostly corrected spontaneously with a decrease of LIV tilt. Thus, SLF for Lenke-5C curves can be a good option regardless of the possible coronal imbalance in the early postoperative period.

Distal adding-on phenomenon in adolescent idiopathic scoliosis patients with thoracolumbar vertebra fusion: A case-control study

The adding-on phenomenon is a common complication in adolescent idiopathic scoliosis (AIS) patients after correction surgery. However, the risk factors of previous studies and the optimal treatment strategies remain controversial. The aim of this study was to identify new risk factors for the adding-on phenomenon after posterior correction surgery in AIS patients and compare different treatment strategies to guide the selection of the lowest instrumented vertebra (LIV).All types of Lenke AIS patients who received correction surgery at our center from January 2009 to July 2014 were analyzed. The anteroposterior and lateral films were evaluated before surgery, at the 2-week follow-up, and at the 2-year or later follow-up. The patients were divided into 2 groups according to whether adding-on was observed at the last follow-up. The factors predictive of the adding-on phenomenon were identified in a multivariate binary logistic regression model. Different methods for LIV selection were compared in both the adding-on group and the control group (no adding-on).Out of the 346 patients reviewed, 92 met the inclusion criteria; 22 of these met the definition for distal adding-on, and were included in adding-on group. The remaining 70 patients were included in the no adding-on group. The average follow-up was 3.6 years. Touch classification (P < .000), Dnfs (P = .005), and vertebra number between LIV and angle velocity (AV) (P = .001) were significantly different between the 2 groups. Age, gender, Risser sign, and screw density were not found to be affiliated with the presence of adding-on. The results of the Scoliosis Research Society (SRS)-22 were not significantly different between the adding-on group and the control group for any section or overall (P > .05). Binary logistic regression results indicated that postoperative LAV deviation from the CSVL and Touch classification were independent predictive factors. Among the 4 methods, only choosing touch type A as LIV shows satisfactory outcome.The Touch classification is an important risk factor that is highly correlated with the incidence of the adding-on phenomenon. The best LIV choice to preserve the lumbar activity segment as much as possible is Touch type C, and no significant difference was observed in the SRS-22 scores between the Touch type C group and the control group in the short-term follow-up.

Five major controversial issues about fusion level selection in corrective surgery for adolescent idiopathic scoliosis: a narrative review

BACKGROUND CONTEXT

Shoulder imbalance, coronal decompensation, and adding-on phenomenon following corrective surgery in patients with adolescent idiopathic scoliosis are known to be related to the fusion level selected. Although many studies have assessed the appropriate selection of the proximal and distal fusion level, no definite conclusions have been drawn thus far.

PURPOSE

We aimed to assess the problems with fusion level selection for corrective surgery in patients with adolescent idiopathic scoliosis, and to enhance understanding about these problems.

STUDY DESIGN

This study is a narrative review.

METHODS

We conducted a literature search of fusion level selection in corrective surgery for adolescent idiopathic scoliosis. Accordingly, we selected and reviewed five debatable topics related to fusion level selection: (1) selective thoracic fusion; (2) selective thoracolumbar-lumbar (TL-L) fusion; (3) adding-on phenomenon; (4) distal fusion level selection for major TL-L curves; and (5) proximal fusion level selection and shoulder imbalance.

RESULTS

Selective fusion can be chosen in specific curve types, although there is a risk of coronal decompensation or adding-on phenomenon. Generally, wider indications for selective fusions are usually associated with more frequent complications. Despite the determination of several indications for selective fusion to avoid such complications, no clear guidelines have been established. Although authors have suggested various criteria to prevent the adding-on phenomenon, no consensus has been reached on the appropriate selection of lower instrumented vertebra. The fusion level selection for major TL-L curves primarily focuses on whether distal fusion can terminate at L3, a topic that remains unclear. Furthermore, because of the presence of several related factors and complications, proximal level selection and shoulder imbalance has been constantly debated and remains controversial from its etiology to its prevention.

CONCLUSIONS

Although several difficult problems in the diagnosis and treatment of adolescent idiopathic scoliosis have been resolved by understanding its mechanism and via technical advancement, no definite guideline for fusion level selection has been established. A review of five major controversial issues about fusion level selection could provide better understanding of adolescent idiopathic scoliosis. We believe that a thorough validation study of the abovementioned controversial issues can help address them.