Criteria for successful correction of thoracolumbar/lumbar curves in AIS patients: results of risk model calculations using target outcomes and failure analysis

Risk factors for postoperative coronal decompensation in adult lumbar scoliosis after posterior correction with osteotomy

INTRODUCTION

To determine potential risk factors for postoperative coronal imbalance following posterior osteotomy for adult scoliosis.

MATERIALS AND METHODS

A total of 74 patients underwent osteotomy for rigid adult lumbar scoliosis. A group of 20 patients with postoperative coronal imbalance was identified. Clinical data and surgical strategies were compared to determine the risk factors, including age, gender, etiology, Cobb angle, preoperative coronal balance distance, direction of preoperative imbalance, T1 tilt, tilt of upper instrumented vertebra (UIV), UIV translation, location of UIV (T6 above or below), fusion to L5 or S1, lower instrumented vertebra (LIV) tilt, LIV rotation, screw density, osteotomy procedure (PSO or SPOs) and use of iliac screws.

RESULTS

Comparison between patients with and without postoperative coronal imbalance showed that postoperative coronal imbalance occurred in older patients and those with degenerative scoliosis as the etiology, UIV above T6, preoperative LIV rotation, preoperative LIV tilt and preoperative coronal imbalance towards the convex side and who underwent Smith-Petersen osteotomy. All seven parameters were included in the logistic regression analysis. UIV above T6 (P = 0.010), LIV rotation (P = 0.012) and preoperative coronal imbalance towards the convex side (P = 0.005) were identified as risk factors for postoperative coronal imbalance after osteotomy.

CONCLUSIONS

Patients with preoperative coronal imbalance towards the convex side (UIV above T6) and LIV rotation were more likely to develop coronal imbalance than those without risk factors. Older patients and those with degenerative scoliosis were also at a relatively higher risk of postoperative coronal imbalance.

Defining risk factors for adding-on in Lenke 1 and 2 AR curves

PURPOSE

To identify curve/correction characteristics associated with adding-on at 2 years after posterior spinal fusion (PSF) in Lenke 1/2 AR curves.

METHODS

A prospective multicenter registry was queried to identify patients with adolescent idiopathic scoliosis (AIS), Lenke 1/2 AR curves, who underwent PSF with a minimum of 2-year follow-up. Patient characteristics as well as pre- and post- operative radiographic variables were evaluated using Classification and Regression Tree (CART) analysis to determine which factors contribute to adding-on.

RESULTS

253 patients treated with PSF were assessed for adding-on, of which 50 met our adding-on criteria. Univariate analysis revealed adding-on was associated several factors including: post-operative thoracic and lumbar curve magnitude (p > 0.001), first erect (FE) end instrumented vertebra (EIV) angulation (p = 0.009) and EIV translation (p = 0.001), younger age (p = 0.027), Risser stage (p = 0.024), and a more proximal lowest instrumented vertebra (LIV) (p < 0.001). Multivariate CART analysis showed the chance of adding-on was more than 2 times greater (42 vs 16%) when the chosen LIV was translated more than 2.7 cm from the CSVL. When the LIV was within 2.7 cm, the post-op risk of adding-on was increased when the LIV was not perfectly leveled (> 0.5°).

CONCLUSION

In Lenke 1 and 2 AR curves, pre-operative LIV translation appears to be an independent risk factor for adding-on; and in those with < 2.7 cm of LIV translation, FE LIV angulation also seems to increase the risk of adding-on. These factors are relevant in determining appropriate LIV selection and aid in identifying patients at risk for developing adding-on.

Clinical outcomes of selective fusion for the thoracolumbar-lumbar curve in patients with Lenke type 6C adolescent idiopathic scoliosis: a preliminary study

Limited evidence is available in the literature regarding the fate of the unfused structural thoracic curve following selective thoracolumbar-lumbar curve fusion (SLF) in Lenke 6C adolescent idiopathic scoliosis (AIS) patients. Therefore, we compared the outcomes of SLF between Lenke 6C and 5C AIS patients. We retrospectively reviewed 31 patients Lenke 5C (n = 18) and Lenke 6C (n = 13) AIS patients who underwent SLF at a single institution. Multiple radiological parameters were measured using whole-spine radiographs taken before and after surgery and at the last follow-up visit. SRS-22 at the final follow-up was obtained for clinical assessment. A total of 31 patients with a mean age of 14.6 years at operation who were followed for a mean of 6.4 years were included in this study. The Cobb angle of the unfused thoracic curve was spontaneously corrected immediately following SLF and increased slightly but not significantly at the final follow-up in both groups (Lenke 5C: pre 33.0°, post 14.4°, final 19.4°, Lenke 6C: pre 46.1°, post 31.7°, final 34.2°). At every time point, the thoracic Cobb angle was significantly larger in the Lenke 6C. SRS-22 score at the final follow-up, including the self-image domain, did not differ between the two groups. In this study, SLF for Lenke 6C AIS achieved a significant spontaneous correction of the unfused thoracic curve and yielded a comparable SRS-22 result at the final follow-up to that of Lenke 5C. Our findings suggest that SLF is a viable treatment option for Lenke 6C AIS.

SpineCloud: image analytics for predictive modeling of spine surgery outcomes

Purpose: Data-intensive modeling could provide insight on the broad variability in outcomes in spine surgery. Previous studies were limited to analysis of demographic and clinical characteristics. We report an analytic framework called "SpineCloud" that incorporates quantitative features extracted from perioperative images to predict spine surgery outcome. Approach: A retrospective study was conducted in which patient demographics, imaging, and outcome data were collected. Image features were automatically computed from perioperative CT. Postoperative 3- and 12-month functional and pain outcomes were analyzed in terms of improvement relative to the preoperative state. A boosted decision tree classifier was trained to predict outcome using demographic and image features as predictor variables. Predictions were computed based on SpineCloud and conventional demographic models, and features associated with poor outcome were identified from weighting terms evident in the boosted tree. Results: Neither approach was predictive of 3- or 12-month outcomes based on preoperative data alone in the current, preliminary study. However, SpineCloud predictions incorporating image features obtained during and immediately following surgery (i.e., intraoperative and immediate postoperative images) exhibited significant improvement in area under the receiver operating characteristic (AUC): AUC = 0.72 ( CI 95 = 0.59 to 0.83) at 3 months and AUC = 0.69 ( CI 95 = 0.55 to 0.82) at 12 months. Conclusions: Predictive modeling of lumbar spine surgery outcomes was improved by incorporation of image-based features compared to analysis based on conventional demographic data. The SpineCloud framework could improve understanding of factors underlying outcome variability and warrants further investigation and validation in a larger patient cohort.

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.

Prevalence, Risk Factors, and Characteristics of the "Adding-On" Phenomenon in Idiopathic Scoliosis After Correction Surgery: A Systematic Review and Meta-Analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

To discuss the prevalence, risk factors, and characteristics of the "adding-on" phenomenon in idiopathic scoliosis (IS).

SUMMARY OF BACKGROUND DATA

There are controversies on the prevalence and risk factors of the "adding-on" phenomenon. In addition, there is no comprehensive study to describe the characteristics of "adding-on" in IS patients.

METHODS

We performed a systematic online search using PubMed, EMBASE, Web of Science, the Cochrane Library, and China WeiPu Library to identify eligible studies. Effect size (ES), odds ratios (OR), and weight mean difference (WMD) with 95% confidence interval (CI) were used to evaluate the incidence, characteristics, and risk factors for "adding-on," respectively.

RESULTS

The overall pooled prevalence of "adding-on" was 14%. Subgroup analysis showed that the prevalence of "adding-on" in Lenke 1A adolescent idiopathic scoliosis (AIS), Lenke 2 AIS, Lenke 5 AIS, and mixed AIS was 15%, 12%, 9%, and 16%, respectively. AIS patients with the "adding-on" phenomenon had smaller proximal thoracic curve (PTC), main thoracic curve (MTC), clavicle angle, T1 tilt angle and radiographic shoulder height (RSH), and larger correction of PTC. Age, Risser sign, preoperative PTC, preoperative MTC, preoperative lumbar curve (LC), preoperative coronal balance and sagittal balance, and T4 tile were identified as risk factors of "adding-on." Selection of lower instrumented vertebra (LIV) was also an important risk factor as LIV-Center Sacral Vertical Line (CSVL), LIV-end vertebra, LIV-Stable Vertebra, and LIV-Neutral vertebra, and deviation of LIV+1 was found to be significantly associated with "adding-on." Besides, postoperative MTC was also significantly different between patients with and without "adding-on."

CONCLUSION

The pooled prevalence varied differently in different types of IS. Patients with "adding-on" had smaller PTC, MTC, angle, T1 tilt angle and RSH, and larger correction of PTC. Younger age, less skeletal maturity, smaller preoperative PTC, smaller preoperative MTC, smaller preoperative LC, larger preoperative coronal, sagittal imbalance, selection of LIV, and overcorrection of coronal and sagittal alignment were risk factors for "adding-on."

LEVEL OF EVIDENCE

4.

Pseudarthrosis in adult and pediatric spinal deformity surgery: a systematic review of the literature and meta-analysis of incidence, characteristics, and risk factors

We conducted a systematic review with meta-analysis and qualitative synthesis. This study aims to characterize pseudarthrosis after long-segment fusion in spinal deformity by identifying incidence rates by etiology, risk factors for its development, and common features. Pseudarthrosis can be a painful and debilitating complication of spinal fusion that may require reoperation. It is poorly characterized in the setting of spinal deformity. The MEDLINE, EMBASE, and Cochrane databases were searched for clinical research including spinal deformity patients treated with long-segment fusions reporting pseudarthrosis as a complication. Meta-analysis was performed on etiologic subsets of the studies to calculate incidence rates for pseudarthrosis. Qualitative synthesis was performed to identify characteristics of and risk factors for pseudarthrosis. The review found 162 articles reporting outcomes for 16,938 patients which met inclusion criteria. In general, the included studies were of medium to low quality according to recommended reporting standards and study design. Meta-analysis calculated an incidence of 1.4% (95% CI 0.9-1.8%) for pseudarthrosis in adolescent idiopathic scoliosis, 2.2% (95% CI 1.3-3.2%) in neuromuscular scoliosis, and 6.3% (95% CI 4.3-8.2%) in adult spinal deformity. Risk factors for pseudarthrosis include age over 55, construct length greater than 12 segments, smoking, thoracolumbar kyphosis greater than 20°, and fusion to the sacrum. Choice of graft material, pre-operative coronal alignment, post-operative analgesics, and sex have no significant impact on fusion rates. Older patients with greater deformity requiring more extensive instrumentation are at higher risk for pseudarthrosis. Overall incidence of pseudarthrosis requiring reoperation is low in adult populations and very low in adolescent populations.

Selective versus hyperselective posterior fusions in Lenke 5 adolescent idiopathic scoliosis: comparison of radiological and clinical outcomes

PURPOSE

Recent literature has reported that the ]progression risk of Lenke 5 adolescent idiopathic scoliosis (AIS) during adulthood had been underestimated. Surgery is, therefore, proposed more to young patients with progressive curves. However, choice of the approach and fusion levels remains controversial. The aim of this study was to analyze the influence of the length of posterior fusion on clinical and radiological outcomes in Lenke 5 AIS.

METHODS

All Lenke 5 AIS operated between 2008 and 2012 were included with a minimum 2-year follow-up. Patients were divided into two groups according to the length of fusion. In the first group (selective), the upper instrumented level (UIV) was the upper end vertebra of the main structural curve and distally the fusion was extended to the stable and neutral vertebra, according to Lenke's classification. In the second group (hyperselective), shorter fusions were performed and the number of levels fused depended on the location of the apex of the curve (at maximum, 2 levels above and below, according to Hall's criteria). Apart from the fusion level selection, the surgical procedure was similar in both groups. Radiological outcomes and SRS-22 scores were reported.

RESULTS

78 patients were included (35 selective and 43 hyperselective). The number of levels fused was significantly higher in the first group (7.8 ± 3 vs 4.3 ± 0.6). None of the patients was fused to L4 in selective group. No correlation was found between length of fusion and complication rate. Eight patients had adding-on phenomenon among which 6 (75%) had initially undergone hyperselective fusions and had significantly higher postoperative lower instrumented vertebra (LIV) tilt. In the adding-on group, LIV was located above the last touching vertebra (LTV) in 62.5% of the cases and above the stable vertebra (SV) in 87.5%. Patients in the selective group reported a significantly lower score in the SRS function domain.

CONCLUSION

Coronal alignment was restored in both groups. Hyperselective posterior fusions can be considered in Lenke 5 AIS, preserving one or two mobile segments, with similar clinical and radiological outcomes. However, selection of the LIV according to SV and LTV need to be accurately analyzed in order to avoid adding-on during follow-up.

Complications of surgical intervention in adult lumbar scoliosis

If nonoperative measures are unsuccessful in managing the pain and disability of adult spinal deformities, surgical correction may provide the potential for significant improvement in a patient's quality of life. However, these procedures have a relatively high risk of complications. Identifying patients that may benefit from surgical intervention requires a thorough understanding of potential complications and managing the risks of any individual patient. Complications do not necessarily result in poor outcomes, and good outcomes are not always complication free. Higher risk patients potentially have more to gain, even if they experience complications. With the rapidly expanding senior population and expanded capabilities to manage high-risk patients, it is helpful to consider the lessons provided by ever expanding databases of outcome measures to refine the surgical decision-making process.

Short fusion strategy for thoracolumbar and lumbar adolescent idiopathic scoliosis using anterior dual-rod instrumentation

Aims

A total of 30 patients with thoracolumbar/lumbar adolescent idiopathic scoliosis (AIS) treated between 1989 and 2000 with anterior correction and fusion surgery using dual-rod instrumentation were reviewed.

Patients and Methods

Radiographic parameters and clinical outcomes were compared among patients with lowest instrumented vertebra (LIV) at the lower end vertebra (LEV; EV group) (n = 13) and those treated by short fusion (S group), with LIV one level proximal to EV (n = 17 patients).

Results

The allocation of the surgical technique was determined by the flexibility of the TL/L curves and/or neutral vertebrae located one level above LEV as determined on preoperative radiographs. If these requirements were met a short fusion was performed. The mean follow-up period was 21.4 years (16 to 27). The mean correction rate at final follow-up was significantly lower in the S group (74 sd 11%) than in the EV group (88 sd 13%) (p = 0.004).Coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, and clinical outcomes evaluated by the Scoliosis Research Society-22 questionnaire scores were equivalent between the two groups.

Conclusion

Short fusion strategy, which uses LIV one level proximal to LEV can be considered as an alternative to the conventional strategy, which includes LEV in the fusion, when highly flexible TL/L curves are confirmed and/or neutral vertebrae are located one level above LEV in patients with thoracolumbar/lumbar AIS curves. Take home message: Short fusion strategy can be considered as an alternative to the conventional strategy in patients with thoracolumbar/lumbar AIS curves undergoing anterior spinal fusion with dual-rod instrumentation. Cite this article: Bone Joint J 2016;98-B:402–9.