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

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°.

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.

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.

Isolated main thoracic curve fusion in idiopathic scoliosis: optimizing radiographic outcomes using lumbar modifiers to guide correction

PURPOSE

Does differential correction of main thoracic curve (MTC) and instrumented LIV angulation based on lumbar modifiers affect radiographic outcomes, and can preoperative supine AP radiograph be used to guide correction for optimal final radiographic alignment.

METHODS

Retrospective analysis of idiopathic scoliosis patients who underwent selective thoracic fusions (LIV T11-L1) for Lenke 1 and 2 curve patterns, < 18 years of age. 2-year minimum follow-up. Optimal outcome meant LIV + 1 of < 5 degrees disk-wedging and C7-CSVL < 2 cm. 82 patients met inclusion criteria (70% female), mean age 14.1 years.

RESULTS

24 patients were A modifier, 21 B modifier, and 37 C modifier. There were 52 optimal and 30 suboptimal outcomes. LIV was not associated with outcome (p = 0.08). For optimal outcomes, A modifiers' MTC improved 65%, B modifiers 65%, and C modifiers 59%. C modifiers' MTC correction was less than A modifiers (p = 0.03) but equivalent to B modifiers' (p = 0.10). A modifiers' LIV + 1 tilt improved 65%, B modifiers 64%, and C modifiers 56%. C modifiers' instrumented LIV angulation was greater than A modifiers' (p < 0.01) but equivalent to B modifiers' (p = 0.06). Preoperative supine LIV + 1 tilt was 16^o in optimal outcomes and 15° in suboptimal outcomes. Instrumented LIV angulation was 9° for both. The correction between preoperative LIV + 1 tilt and instrumented LIV angulation was not significantly different between groups (p = 0.67).

CONCLUSION

Differential MTC and LIV tilt correction based on lumbar modifier may be a valid goal. Optimizing radiographic outcome by matching instrumented LIV angulation to preoperative supine LIV + 1 tilt could not be proven.

LEVEL OF EVIDENCE

IV.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

STUDY DESIGN

Retrospective analysis of a prospectively collected data.

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Subjective perception of spinal deformity after selective versus non-selective fusion of Lenke 1C curves

PURPOSE

To assess the self-image perception and the Quality-of-Life (QoL) in female adolescents, with Lenke 1C scoliosis curves, treated with selective versus non-selective posterior spinal instrumentation and fusion (PSF).

METHODS

Patients undergoing PSF for idiopathic adolescent scoliosis (AIS) were recruited and divided into two groups: patients managed with selective thoracic fusion (STF) were included in Group A, whereas patients treated with non-selective fusion (N-STF) in Group B. Each patient completed the Italian version of the Scoliosis Research Society-22R questionnaire (SRS-22R), the Quality-of-Life Profile for Spinal Deformities questionnaire (QLPSD) and the Spinal Appearance Questionnaire (SAQ), before surgery and at 24-month follow-up.

RESULTS

One hundred and fifty seven female patients (mean age 16.38) were included in this study. 80 patients underwent STF, while 77 patients received N-STF. At 24-month follow-up, patients managed with N-STF showed better SRS-22R self-image mean score (p = .012), SRS-22R satisfaction mean score (p = .033), QLPSD body image mean score (p = .005), but worse SRS-22 function mean score (p = .006) and QLPSD back flexibility mean score (p = .007), compared with patients who underwent STF. In terms of self-image perception, patients undergoing STF showed significantly worse SAQ total mean score (p = .002), SAQ appearance mean score (p = .001) and SAQ expectation (p = .001). We found a significant correlation between SAQ appearance mean score and SRS-22R self-image (R = - 0.721), SRS-22 mental health (R = - 0.8), QLPSD psychosocial functioning (R = 0.7) and QLPSD back flexibility (R = 0.8).

CONCLUSION

Although the STF of Lenke 1C curves provides better functional outcomes, in the present study, female patients receiving STF revealed a worse perceived body image, compared with patients treated with N-STF, at 24-month follow-up. Particular attention should be addressed to the preoperative patient's mental health and body image perception, when choosing between STF and N-STF.

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.

Matching correction of main and compensatory curves is critical for immediate postoperative coronal balance in correction of severe adult idiopathic scoliosis

PURPOSE

To analyze the correlation between immediate postoperative coronal imbalance and the matching degree of the correction rates of the main curve and compensatory curves in the surgical treatment of severe adult idiopathic scoliosis.

METHODS

Patients were categorized into three types based on the preoperative coronal balance status (type A = balance, type B = shifted to cave side and type C = shifted to convex side), and each type was further divided into two subgroups based on the postoperative coronal balance status (balance and imbalance). Different coronal parameters before and after operations were calculated and compared.

RESULTS

The rate of postoperative CIB was highest in type C patients (53.8%) and lowest in type A patients (31.5%). To avoid postoperative CIB, the value of the postoperative CR_main should fall within the range of 1.001 × CR_comp ± 2.84% in type A patients, 1.112 × CR_comp + 3.3% ± 5.02% in type B patients and 0.907 × CR_comp - 2.5% ± 4.38% in type C patients.

CONCLUSION

Mismatch between the correction rates of the main curve and compensation curves is a critical cause of immediate postoperative CIB. The relatively equal correction of the main curve and compensatory curves is essential for type A patients to achieve postoperative coronal balance, while the correction rate of the main curve should be higher than the compensatory curves in type B patients and vice versa in type C patients. Three formulas for the three different types were developed to provide helpful guidance information for surgical planning.

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.