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.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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.

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.

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.

Spontaneous derotation of compensatory lumbar curve after thoracic fusion in adolescent idiopathic scoliosis

Introduction: Currently, excellent three-dimensional correction can be achieved with use of segmental pedicle screw fixation in adolescent idiopathic scoliosis (AIS). In the majority of patients with major thoracic curves, selective thoracic fusion (STF) may be considered to maximize motion segment of the unfused lumbar spine. This study aimed to investigate the extent of spontaneous derotation of the lumbar curve following STF. Methods: AIS patients who underwent STF using posterior pedicle screw fixation were retrospectively reviewed. Angle of vertebral rotation was defined as the difference between the axial rotation angles of the apical vertebra and S1 vertebra on axial CT images. Radiographic measurements included major thoracic curve, thoracolumbar/lumbar curve (preoperative and postoperative), and side-bending curve. The relationships between the axial rotation of the lumbar spine and radiographic measurements were also analyzed. Results: Thirty patients (all females) were included. Preoperative thoracic Cobb measured 62.1±9°, which improved to 20.3±5° at 2 years postoperatively, resulting in 67% correction. Preoperative lumbar Cobb measured 38.0±9°, which spontaneously improved to 19.0±7°, indicating a 50% correction. Preoperatively, the axial rotation of apical lumbar vertebra was 10.2±5.5°, which changed to 7.0±4.8° (32% spontaneous correction). Comparing the correction between the axial rotation of the lumbar spine and other parameters, postoperative angle of axial rotation correlated well with preoperative (r=0.79) and postoperative (r=0.82) lumbar Cobb angle. Meanwhile, the improvement of axial rotation of the lumbar spine correlated with postoperative thoracic curve (r=－0.42), postoperative lumbar curve (r=－0.57), and thoracic apical translation change (r=0.43). Conclusions: In AIS patients with major thoracic curves, spontaneous axial derotation of the lumbar curves occurred with a mean correction rate of 32% after STF. A greater spontaneous derotation of the lumbar curve would be related to correction of the thoracic curve.

Timing of Changes in Three-Dimensional Spinal Parameters After Selective Thoracic Fusion in Lenke 1 Adolescent Idiopathic Scoliosis: Two-Year Follow-up

STUDY DESIGN

Retrospective analysis of the prospectively collected data.

OBJECTIVE

To investigate the relationship between the axial rotation of the unfused lumbar spine and the parameters of the instrumented thoracic spine at varying time points after selective thoracic fusion (STF) in Lenke 1B and 1C adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The impact of STF on the spontaneous lumbar curve correction in AIS has been studied mainly in the frontal planes. The relationship between the spontaneous transverse plane correction of the lumbar spine and the parameters of the fused thoracic spine is not well documented.

METHODS

Twenty-one Lenke 1B and 1C patients who had received STF with minimum two years' follow-up were selected. Thoracic and lumbar Cobb angles, kyphosis, lordosis, and thoracic and lumbar apical vertebrae rotations were measured at preoperative, first-erect, six-month, one-year, and two-year follow-ups. The association between the lumbar apical vertebral rotation and other thoracic and lumbar variables at different time points were determined using regression analysis. The variables significantly predicting the lumbar axial rotation correction at two years were determined from the preceding follow-up visits.

RESULTS

Kyphosis, thoracic Cobb, thoracic apical vertebral rotation, and lumbar Cobb were significantly different between the preoperative and all the postoperative follow-ups (p < .05). At the two-year follow-up, a decrease in thoracic rotation and lumbar Cobb and a higher residual thoracic Cobb were associated with an improved spontaneous lumbar rotation (R² = 0.41, p < .05). Lumbar rotation at two years was predicted from thoracic derotation and lumbar Cobb at first erect (R² = 0.30, p < .05).

CONCLUSION

Spontaneous lumbar curve rotation correction correlated to the fused and unfused spinal parameters in the three anatomic planes. The relationship between thoracic and lumbar rotation persist up to two years after STF. Thoracic derotation is an important factor determining the lumbar rotation correction at two years after STF.

Thoraco-lumbar selective fusion in adolescent idiopathic scoliosis with Lenke C modifier curves: clinical and radiographic analysis at 10-year follow-up

PURPOSE

To examine the radiological and clinical outcomes of a single-center case series of selective thoracic fusions (STF) in adolescent idiopathic scoliosis with Lenke C modifier curves, with a long-term follow-up.

METHODS

We evaluated at 6 months and 10 years different radiological parameters on both thoracic and lumbar districts: coronal curves, sagittal curves, apical vertebral translation (AVT), and apical vertebral rotation (AVR). The clinical outcome was determined using the SRS 22 score. Data were also analyzed dividing the patients by their Risser and Lenke scores.

RESULTS

In examining 90 patients we reported a radiological benefit from STF on both thoracic and lumbar districts. The corrections in the values of both coronal curves, AVT, and AVR are relevant at 6 months and do not significantly vary at the latest follow-up. Sagittal curves are not relevantly affected at any time point. All the SRS 22 score evaluations showed significant improvement at 6 months, in particular, the self-image analysis. A further improvement was also reported at 10 years, in particular in pain and function scores. At no time point were significant differences retrieved by comparing SRS 22 results as divided by Risser or Lenke grading systems.

CONCLUSIONS

STF is an effective treatment option both in clinical and radiographical terms. The results at 10-year follow-up confirm both the stability of the correction and the improvement of the clinical outcome scores. Risser and Lenke grading systems are not relevant variables predictive of clinical efficacy.

Onset and remodeling of coronal imbalance after selective posterior thoracic fusion for Lenke 1C and 2C adolescent idiopathic scoliosis (a pilot study)

Background

Postoperative coronal imbalance is a significant problem after selective thoracic fusion for primary thoracic and compensatory lumbar curves in adolescent idiopathic scoliosis (AIS). However, longitudinal studies on postoperative behavior of coronal balance are lacking. This multicenter retrospective study was conducted to analyze factors related to onset and remodeling of postoperative coronal imbalance after posterior thoracic fusion for Lenke 1C and 2C AIS.

Methods

Twenty-one Lenke 1C or 2C AIS patients, who underwent posterior thoracic fusion ending at L3 or above, were included with a minimum 2-year follow-up. The mean patients’ age was 15.1 years at the time of surgery. Radiographic measurements were performed on Cobb angles of the main thoracic (MT) and thoracolumbar/lumbar (TLL) curves and coronal balance. Factors related to the onset of immediately postoperative coronal decompensation (IPCD) and postoperative coronal balance remodeling (PCBR), defined as an improvement of coronal balance during postoperative follow-up, were investigated using comparative and correlation analyses.

Results

Mean Cobb angles for the MT and TLL curves were 57.3° and 42.3° preoperatively and were corrected to 22.8° and 22.5° at final follow-up, respectively. Mean preoperative coronal balance of −3.8 mm got worse to −21.2 mm postoperatively, and regained to −12.0 mm at final follow-up. Coronal decompensation was observed in two patients preoperatively, in ten patients immediately postoperatively, and in three patients at final follow-up. The preoperative coronal balance and lowest instrumented vertebra (LIV) selection relative to stable vertebra (SV) were significantly different between patients with IPCD and those without. PCBR had significantly negative correlation with immediately postoperative coronal balance.

Conclusions

IPCD after posterior thoracic fusion for Lenke 1C and 2C AIS was frequent and associated with preoperative coronal balance and LIV selection. However, most patients with IPCD regained coronal balance through PCBR, which was significantly associated with immediately postoperative coronal balance. A fixation more distal to SV shifted the coronal balance further to the left postoperatively.

Does a dual attending surgeon strategy confer additional benefit for posterior selective thoracic fusion in Lenke 1 and 2 adolescent idiopathic scoliosis (AIS)? A prospective propensity matching score analysis

BACKGROUND CONTEXT

With an increased cost of adolescent idiopathic scoliosis (AIS) surgery over the past 10 years, improvement of patient safety and optimization of the surgical management of AIS has become an important need. A dual attending surgeon strategy resulted in reduction of blood loss and complication rate.

PURPOSE

This study aimed to investigate the perioperative outcome of posterior selective thoracic fusion in Lenke 1 and 2 AIS patients comparing a single versus a dual attending surgeon strategy.

STUDY DESIGN

A prospective cohort study was carried out.

PATIENT SAMPLE

The study sample comprised 60 patients OUTCOME MEASURE: Operative duration, blood loss, postoperative hemoglobin, need for transfusion, morphine usage, and duration of hospital stay were the outcome measures.

METHODS

A total of 116 patients who underwent posterior selective thoracic fusion from two centers were prospectively recruited. The patients were grouped into Group 1 (single surgeon) and Group 2 (two surgeons). One-to-one matching analysis using "propensity score-matched cohort patient sampling method" was done for age, gender, height, weight, preoperative Cobb angle, number of fusion level, and Lenke classification. The outcome measures included operative duration, blood loss, postoperative hemoglobin, need for transfusion, morphine usage, and duration of hospital stay. This study was self-funded with no conflict of interest.

RESULTS

From 86 patients who were operated by the two surgeons (Group 2), 30 patients were matched with 30 patients who were operated by a single surgeon (Group 1). Group 2 (164.0±25.7 min) has a significantly shorter operation duration (p=.000) compared with Group 1 (257.3±51.4 min). The total blood loss was significantly more (p=.009) in Group 1 (1254.7±521.5 mL) compared with Group 2 (893.7±518.4 mL). There were seven patients (23.3%) in Group 1 who received allogenic blood transfusion (p<.05). The morphine usage and average hospital stay were significantly lower in Group 2, 22.4±10.7 mg and 3.4±0.7 days, respectively (p<.05). In Group 1, there was one patient who developed a superficial wound infection. No other major complications were noted.

CONCLUSIONS

A dual attending surgeon strategy was superior to a single surgeon strategy in posterior selective thoracic fusion in Lenke 1 and 2 AIS patients and will lead to a faster operation, reduced intraoperative blood loss, reduced risk of allogenic transfusion, reduced morphine requirement, and shorter hospital stay.

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

STUDY DESIGN/SETTING

Matched cohort.

OBJECTIVE

To evaluate thoracic and thoracolumbar sagittal Cobb angles in patients undergoing either selective thoracic fusion (STF) or nonselective thoracic fusion (NSTF) for Lenke 1C adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The Lenke classification is used to guide fusion levels in AIS. For some curve types, including 1C, there is a disparity in practice regarding whether the thoracolumbar/lumbar curve should be included in the arthrodesis. The impact of performing an NSTF on sagittal parameters has not been adequately evaluated.

METHODS

A multicenter database of AIS was queried for patients with right-sided 1C curves treated with posterior correction and fusion. A matched cohort for each group was created based on age, gender, preoperative Cobb angles, and Scoliosis Research Society-22R domain scores. Independent t tests for continuous variables and Fisher exact test for categorical variables were used to compare the STF and NSTF groups.

RESULTS

Thirty-eight patients who underwent NSTF were matched to 38 patients in the STF. An average of 8.0 levels were fused in the STF group and 11.6 in the NSTF group (p < .001). Preoperative and radiographic variables were similar between the two groups. Postoperatively, there was a statistically significant difference between the STF and NSTF sagittal Cobb in the thoracic spine, 26.9° and 21.7° (p = .013). The greatest difference was in the thoracolumbar sagittal Cobb, which increased to 4.3° kyphosis in the STF group and decreased to 9° of lordosis in the NSTF group (p < .001). Residual thoracolumbar/lumbar scoliosis was 25.5° in the STF group and 14.5° in the NSTF group (p < .001).

CONCLUSIONS

STF in 1C curves preserves lumbar motion segments but may be associated with an increase in thoracic and thoracolumbar kyphosis compared to NSTF. As expected, residual thoracolumbar/lumbar scoliosis was less in the NSTF group compared to the STF group. Although the long-term implications of these changes are unknown, consideration of sagittal balance is critical. Following these patients in the medium and long term will provide important information to guide fusion levels.

LEVEL OF EVIDENCE

II.

Selective Thoracic Fusion Provides Similar Health-Related Quality of Life but Can Cause More Lumbar Disc and Facet Joint Degeneration: A Comparison of Adolescent Idiopathic Scoliosis Patients With Normal Population 10 Years After Surgery

OBJECTIVES

To evaluate the long-term behavior of the lumbar curve in patients with adolescent idiopathic scoliosis treated with selective thoracic fusion and to assess the clinical and radiologic outcomes in this fusion group compared with an age- and gender-matched group.

SUMMARY OF BACKGROUND DATA

Selective thoracic fusion for the treatment of adolescent idiopathic scoliosis (AIS) preserves lumbar motion segments but leaves a residual deformity. By avoiding fusion of the lumbar spine, a greater mobility may be preserved, which may be an advantage in long-term follow-up in terms of degenerative changes in unfused segments.

METHODS

Group A included 25 AIS patients with mean a age of 23.8 years and a mean 11.4 years of follow-up. Group B included 30 age- and gender-matched subjects without any deformity. Preoperative, postoperative, and follow-up radiographs were reviewed. All patients had MRIs taken at the final follow-up in order to evaluate disc degeneration (DD) and facet joint degeneration (FJD) at the unfused lumbar spine. Clinical evaluation was done by using Scoliosis Research Society-22R, Oswestry Disability Index, and numerical rating scale.

RESULTS

Sagittal and coronal balance and lowest instrumented vertebra disc angulation were stable over time. Mean grading of lumbar DD was 2.16 (2-4) in Group A and 1.86 (1-3) in Group B. Lumbar FJDs were 2.05 (1-4) in Group A and 1.60 (1-3) in Group B. There was significant difference between the two groups for DD except for the L4-L5 level (p = .26). FJD was significantly higher in the L1-L2 and L2-L3 levels (L1-L2, p = .002, L2-L3, p = .002) but not for the other levels. Outcome scores were similar without significant differences between the two groups (p > .05).

CONCLUSION

Selective thoracic fusion provides satisfactory outcomes at more than 10 years of follow-up. Our study demonstrated a moderate increase in the rate of disc degeneration in the unfused segments. Facet joint degeneration was significant at the upper two levels adjacent to the lowest instrumented vertebra.

The efficacy of proximal lumbar curve flexibility in patients with main thoracic adolescent idiopathic scoliosis treated by selective thoracic fusion surgery

Study Design

Retrospective radiographic study.

Purpose

To evaluate the efficacy of the proximal lumbar curve flexibility compared with the traditional whole lumbar curve flexibility in patients with main thoracic adolescent idiopathic scoliosis (MT-AIS).

Overview of Literature

Traditionally the flexibility of the whole lumbar curve was measured, and the flexibility of the proximal lumbar curve was not analyzed in any study.

Methods

Twenty-eight MT-AIS patients treated by anterior selective thoracic fusion (STF) were evaluated after mean follow-up of 50.1 months (range, 25 to 116 months). The male : female ratio was in 5 : 23. The man age at surgery was 14 years and 8 months (range, 11.4 to 18.4 years). The lumbar curve was divided into the proximal and distal curves by the lumbar apex.

Results

The mean final correction rates (CR)/(flexibilities) of the MT, lumbar, proximal lumbar, and distal lumbar curves were 65.2%/(50.5%), 61.9%/(92.8%), 65.3%/(90.9%), and 36.4%/(134%), respectively. With the final lumbar CR, the lumbar flexibility (r = 0.267, p > 0.05) and the proximal lumbar flexibility (r = 0.327, p > 0.05) was similarly correlated. The mean lumbar CR was similar to the proximal lumbar CR (61.9% vs. 65.3%, p = 0.305). And the correlation between the flexibility and the CR was significant only in the proximal lumbar curve (r = 0.457, p < 0.05), but not in the lumbar curve (r = 0.267, p > 0.05) or the distal lumbar curve (r = 0.175, p > 0.05).

Conclusions

The proximal lumbar curve flexibility may be an alternative method of measuring the lumbar flexibility in MT-AIS patients treated by STF.

Axial plane lumbar responses after anterior selective thoracic fusion for main thoracic adolescent idiopathic scoliosis

Study Design

A retrospective radiographic study.

Purpose

To evaluate the axial plane lumbar responses after anterior selective thoracic fusion (STF) in patients with main thoracic adolescent idiopathic scoliosis (MT-AIS).

Overview of Literature

Anterior scoliosis surgery induces more MT derotation through disc preparation than posterior surgery.

Methods

Twenty-eight MT-AIS patients treated with STF were evaluated after a minimum follow-up (FU) of 2 years. The MT and lumbar coronal angles, as well as the MT and lumbar rotational angles at the most rotated vertebrae were measured.

Results

At the last FU, the MT coronal correction and derotation rates were 65% and 41%, respectively. The lumbar coronal correction rate was 61% but there was minimal lumbar derotation (2%). Nine cases were decompensated (coronal balance >10 mm). After surgery, the compensated and decompensated groups showed similar MT coronal and axial correction rates. During the FU, the MT and lumbar apecies rotated in the same direction (r=0.443). In addition, significant MT derotation occurred in the decompensated group with increasing lumbar rotational correction loss. At the last FU, while the MT coronal correction was similar between the two groups, there was more MT derotation in the decompensated group. Furthermore, the MT rotational change was strongly associated with the coronal C7 plumb line position (r=0.728).

Conclusions

After anterior STF in patients with MT-AIS, the final MT derotation is strongly associated with the coronal C7 plumb line position. During the FU, the excessive MT derotation in the decompensated group was attributed to excessive lumbar rotational correction loss.

Sagittal plane lumbar responses after anterior selective thoracic fusion for main thoracic adolescent idiopathic scoliosis

Study Design

A retrospective radiographic study.

Purpose

To verify the correlation of sagittal and coronal plane changes after selective thoracic fusion in main thoracic (MT) adolescent idiopathic scoliosis (AIS).

Overview of Literature

Sagittal plane deformity is known to be essential in the evolution of scoliosis.

Methods

Twenty-eight MT AIS patients treated by anterior selective thoracic fusion were evaluated after minimal follow-up of two years. The unfused lumbar area was divided into proximal and distal parts by the lumbar apex in the coronal plane, and into proximal and distal lumbar lordosis by L2 in the sagittal plane. Surgical motion (the difference between preoperative and postoperative values) and follow-up motion (the difference between postoperative and the last follow-up values) were compared.

Results

Immediately after surgery, as thoracic kyphosis increased, lumbar lordosis decreased (r=0.734); proximal lumbar lordosis increased, and distal lumbar lordosis decreased. The proximal lumbar area was mobilized in the sagittal plane, and was straightened in the coronal plane. However, the distal lumbar area was stabilized in the sagittal plane, and showed resistant motion against MT translation in the coronal plane. The surgical motion was correlated to the follow-up motion, i. e., was regulated during follow-up, and the regulatory motion was more precise in the distal than proximal lumbar area in both sagittal and coronal planes.

Conclusions

Sagittal and coronal motions were co-related; optimal sagittal motions were necessary for optimal coronal motions after anterior selective thoracic fusion for MT AIS. Proximal and distal lumbar motions were different for different roles; the proximal lumbar area played a role as a bumper to absorb the MT translatory force, and the distal lumbar area played a role of resistance against MT translation.