Current status of adult spinal deformity

Explainable Machine Learning Approach to Prediction of Prolonged Intensive Care Unit Stay in Adult Spinal Deformity Patients: Machine Learning Outperforms Logistic Regression

Study DesignRetrospective cohort study.ObjectivesProlonged ICU stay is a driver of higher costs and inferior outcomes in Adult Spinal Deformity (ASD) patients. Machine learning (ML) models have recently been seen as a viable method of predicting pre-operative risk but are often 'black boxes' that do not fully explain the decision-making process. This study aims to demonstrate ML can achieve similar or greater predictive power as traditional statistical methods and follows traditional clinical decision-making processes.MethodsFive ML models (Decision Tree, Random Forest, Support Vector Classifier, GradBoost, and a CNN) were trained on data collected from a large urban academic center to predict whether prolonged ICU stay would be required post-operatively. 535 patients who underwent posterior fusion or combined fusion for treatment of ASD were included in each model with a 70-20-10 train-test-validation split. Further analysis was performed using Shapley Additive Explanation (SHAP) values to provide insight into each model's decision-making process.ResultsThe model's Area Under the Receiver Operating Curve (AUROC) ranged from 0.67 to 0.83. The Random Forest model achieved the highest score. The model considered length of surgery, complications, and estimated blood loss to be the greatest predictors of prolonged ICU stay based on SHAP values.ConclusionsWe developed a ML model that was able to predict whether prolonged ICU stay was required in ASD patients. Further SHAP analysis demonstrated our model aligned with traditional clinical thinking. Thus, ML models have strong potential to assist with risk stratification and more effective and cost-efficient care.

What if You Could Treat the Same Patient Again, Would You do the Exact Same Spine Surgery? A Multi-Surgeon Survey of Their Own Revisions

Study DesignCase-based survey.ObjectivesThis study aims to investigate what a group of surgeons learned from their own revisions, and what they would do differently today.MethodsA multi-center database of ASD surgical patients was queried to identify those with at least 2 surgical procedures performed by the same surgeon between 2009 and 2019. A clinical vignette was created for each case including demographics, a timeline of events, radiographs/measurements, patient-reported outcomes, complications, and surgical strategies used for the index and revision surgeries. The operative surgeon was then asked to fill out a five-question survey aimed at determining factors that contribute to operative decision-making and planning.Results86 patients were operated on by 6 participating surgeons for both index and revision ASD surgery. The revised patients had similar follow-up compared to the non-revised group (P = 0.73), with the most common complications indicating a need for revision surgery being proximal junctional failure (42%) and pseudoarthrosis (28%). Surgeons reported that they would not change their surgical strategy in 52.3% of the cases. The leading cause for revision was hardware/instrumentation issues (24.4%). Learning points included rod-related choice (23.3%), level selection (19.8), PJF prophylactic strategy (15.1%), and sagittal alignment objective (11.6%).ConclusionsSurgeons saw opportunity in nearly half of the cases to improve outcomes by changing something in the original surgery. While 40% of the failures remained unexplained from the surgeons' perspective, this study highlights the capacity for adopting changes in adult spinal deformity surgery and illuminates the reasoning behind certain surgical decisions.

Male patients with adult spinal deformity: sex differences in demographics, radiography, and complications

PURPOSE

This study aimed to investigate sex-related differences in demographics, radiography, and perioperative complications in adult spinal deformity (ASD) surgeries.

METHODS

This retrospective cohort, single-center study enrolled patients who underwent long-instrumented fusion from the thoracic spine to the ilium for ASD, with a minimum follow-up of 2 years. The incidence of preoperative comorbidities, perioperative complications, and postoperative mechanical complications was analyzed.

RESULTS

Of the 323 patients, ASD was more common in females (85.8%). The T-score in female patients was lower than that in male patients (-1.6 ± 1.1 vs.- 0.8 ± 1.0, p = 0.02). Male patients demonstrated lower rates of degenerative kyphoscoliosis (83.4% vs. 65.2%, p = 0.004) but higher rates of neuromuscular disease (7.6% vs. 21.7%, p = 0.003) than female patients. Male patients exhibited higher prevalence of cardiovascular disease (4.0% vs. 13.5%, p = 0.034) and hemodialysis (2.5% vs. 10.8%, p = 0.035). Additionally, male patients had a higher Charlson Comorbidity Index than female patients (0.8 ± 1.1 vs. 1.4 ± 1.1, p = 0.001). Moreover, male patients showed higher perioperative complications in surgical site infection (5.1% vs. 15.2%, p = 0.018). However, the incidence of proximal junctional failure (43.3% vs. 39.1%, p = 0.595) and rod fracture (27.8% vs. 26.1%, p = 0.81) was not different.

CONCLUSIONS

Male patients with ASD demonstrated frequent pathology of neuromuscular disease, preoperative comorbidities, and surgical site infection, necessitating careful preoperative checkups and intraoperative care.

Dose-response relationship between symptom duration and postoperative patient-reported outcomes in patients with adult spinal deformity

OBJECTIVE

To ascertain whether preoperative symptom duration elevated the risk of adverse patient-reported outcomes (PROs) and to further delve into whether the existence of a dose-response relationship in patients with adult spinal deformity (ASD).

METHODS

The retrospective cohort comprised consecutive patients who underwent spinal corrective surgery from January 2018 to May 2022. Demographic, radiological and surgical factors were included from the electronic medical records. To identify the impact of mismatched variables, we performed conditional logistic regression after adjusting for potential confounding factors. Further, nonlinear relationship between symptom duration and postoperative unfavorable PROs at 24-month follow-up was conducted based on restricted cubic splines (RCS) analysis, with the adjustments for possible confounders. If a nonlinear relationship was identified, a two-piecewise regression model would be employed to ascertain the threshold effect. Finally, the result of receiver operating characteristic (ROC) curve was employed to further corroborated the rationality of RCS results.

RESULTS

We matched 122 controls to 61 unfavorable PROs patients. In the fully adjusted linear model, for every additional month of symptom duration, the risk of unfavorable patient-reported outcomes (u-PROs) increased by 79%, with an odds ratio of 1.79 (95% CI: 1.25-2.04, p < 0.001). Patients with 6-18 months of symptom duration had comparable risk of u-PRO, whereas patients with more than 24 months had an increasingly higher risk of u-PRO (OR = 4.74, 95% CI 3.11 - 7.93, p < 0.001). Based on the results of the restricted cubic spline (RCS) analysis with three knots, a significant nonlinear relationship was observed. Notably, we found a substantial increase in the risk of u-PROs when the duration of symptoms exceeded 18.4 months. Additionally, ROC curve with an optimal cut-off of 18.5 months was identified, which verified the reliability of RCS analysis.

CONCLUSIONS

We determine that 18.4 months was a threshold of preoperative symptom duration that shifted the risk of unfavorable PROs after spinal corrective surgery, and there was a dose-response relationship.

Topping-Off a Long Thoracic Stabilization With Semi-Rigid Constructs May Have Favorable Biomechanical Effects to Prevent Proximal Junctional Kyphosis: A Biomechanical Comparison

Study DesignIn-vitro cadaveric biomechanical study.ObjectivesLong posterior spinal fusion is a standard treatment for adult spinal deformity. However, these rigid constructs are known to alter motion and stress to the adjacent non-instrumented vertebrae, increasing the risk of proximal junctional kyphosis (PJK). This study aimed to biomechanically compare a standard rigid construct vs constructs "topped off" with a semi-rigid construct. By understanding semi-rigid constructs' effect on motion and overall construct stiffness, surgeons and researchers could better optimize fusion constructs to potentially decrease the risk of PJK and the need for revision surgery.MethodsNine human cadaveric spines (T1-T12) underwent non-destructive biomechanical range of motion tests in pure bending or torsion and were instrumented with an all-pedicle-screw (APS) construct from T6-T9. The specimens were sequentially instrumented with semi-rigid constructs at T5: (i) APS plus sublaminar bands; (ii) APS plus supralaminar hooks; (iii) APS plus transverse process hooks; and (iv) APS plus short pedicle screws.ResultsAPS plus transverse process hooks had a range of motion (ie, relative angle) for T4-T5 and T5-T6, as well as an overall mechanical stiffness for T1-T12, that was more favourable, as it reduced motion at adjacent levels without a stark increase in stiffness. Moreover, APS plus transverse process hooks had the most linear change for range of motion across the entire T3-T7 range.ConclusionsPresent findings suggest that APS plus transverse process hooks has a favourable biomechanical effect that may reduce PJK for long spinal fusions compared to the other constructs examined.

Opioid Use Prior to Adult Spine Deformity Correction Surgery is Associated With Worse Pre- and Postoperative Back Pain and Prolonged Opioid Demands

Study DesignProspective multicenter database post-hoc analysis.ObjectivesOpioids are frequently prescribed for painful spinal conditions to provide pain relief and to allow for functional improvement, both before and after spine surgery. Amidst a current opioid epidemic, it is important for providers to understand the impact of opioid use and its relationship with patient-reported outcomes. The purpose of this study was to evaluate pre-/postoperative opioid consumption surrounding ASD and assess patient-reported pain outcomes in older patients undergoing surgery for spinal deformity.MethodsPatients ≥60 years of age from 12 international centers undergoing spinal fusion of at least 5 levels and a minimum 2-year follow-up were included. Patient-reported outcome scores were collected using the Numeric Rating Scale for back and leg pain (NRS-B; NRS-L) at baseline and at 2 years following surgery. Opioid use, defined based on a specific question on case report forms and question 11 from the SRS-22r questionnaire, was assessed at baseline and at 2-year follow-up.ResultOf the 219 patients who met inclusion criteria, 179 (81.7%) had 2-year data on opioid use. The percentages of patients reporting opioid use at baseline (n = 75, 34.2%) and 2 years after surgery (n = 55, 30.7%) were similar (P = .23). However, at last follow-up 39% of baseline opioid users (Opi) were no longer taking opioids, while 14% of initial non-users (No-Opi) reported opioid use. Regional pre- and postoperative opioid use was 5.8% and 7.7% in the Asian population, 58.3% and 53.1% in the European, and 50.5% and 40.2% in North American patients, respectively. Baseline opioid users reported more preoperative back pain than the No-Opi group (7.0 vs 5.7, P = .001), while NRS-Leg pain scores were comparable (4.8 vs 4, P = .159). Similarly, at last follow-up, patients in the Opi group had greater NRS-B scores than Non-Opi patients (3.2 vs 2.3, P = .012), but no differences in NRS-Leg pain scores (2.2 vs 2.4, P = .632) were observed.ConclusionsIn this study, almost one-third of surgical ASD patients were consuming opioids both pre- and postoperatively world-wide. There were marked international variations, with patients from Asia having a much lower usage rate, suggesting a cultural influence. Despite both opioid users and nonusers benefitting from surgery, preoperative opioid use was strongly associated with significantly more back pain at baseline that persisted at 2-year follow up, as well as persistent postoperative opioid needs.

Comparison of Outcomes Between Staged and Same-Day Circumferential Spinal Fusion for Adult Spinal Deformity: Systematic Review and Meta-Analysis

BACKGROUND

Adult spinal deformity (ASD) is a prevalent condition often treated with circumferential spinal fusion (CF), which can be performed as staged or same-day procedures. However, evidence guiding the choice between these approaches is lacking.

OBJECTIVE

This study aims to compare patient outcomes following staged and same-day CF for ASD.

METHODS

Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a comprehensive literature search was conducted in PubMed, MEDLINE, Embase, Cochrane CENTRAL, Web of Science, and Scopus. Eligibility criteria included studies comparing outcomes following staged and same-day CF in adults with ASD. Searches were exported to Covidence, and records were deduplicated automatically. Title and abstract screening, full-text review, and data extraction were performed by two independent reviewers, with all conflicts being resolved by a third reviewer. A meta-analysis was conducted for outcomes reported in 3 or more studies.

RESULTS

Seven studies with 741 patients undergoing CF for ASD were included in the review (staged: n=331, 44.7% and same-day: n=410, 55.3%). Four studies that had comparable outcomes were merged for the quantitative meta-analysis and split based on observed measures. The meta-analysis revealed significantly shorter hospital length of stay (mean difference 3.98, 95% CI 2.23-5.72 days; P<.001) for same-day CF. Three studies compared the operative time between staged and same-day CF, with all reporting a lower mean operative time for same-day CF (mean between 291-479, SD 129 minutes) compared to staged CF (mean between 426-541, SD 124 minutes); however, inconsistent reporting of mean and SD made quantitative analyses unattainable. Of the 4 studies that compared estimated blood loss (EBL) in the relevant groups, 3 presented a lower EBL (mean between 412-1127, SD 954 mL) in same-day surgery compared to staged surgery (mean between 642, SD 550 to 1351, SD 869 mL). Both studies that reported intra- and postoperative adverse events showed more intraoperative adverse events in staged CF (10.9% and 13.6%, respectively) compared to same-day CF (9.1% and 3.6%, respectively). Four studies measuring any perioperative adverse events showed a higher incidence of adverse events in staged CF than all studies combined. However, quantitative analysis of EBL, intraoperative adverse events, and perioperative adverse events found no statistically significant difference. Postoperative adverse events, reoperation, infection rates, and readmission rates showed inconsistent findings between studies. Data quality assessment revealed a moderate degree of bias for all included studies.

CONCLUSIONS

Same-day CF may offer shorter operating time and hospital stay compared to staged CF for ASD. However, there was marked heterogeneity in perioperative outcomes reporting, and continuous variables were inconsistently presented. This underscored the need for standardized reporting of clinical variables and patient-reported outcomes and higher evidence of randomized controlled trials to elucidate the clinical superiority of either approach.

TRIAL REGISTRATION

PROSPERO CRD42022339764; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=339764.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.2196/42331.

Anatomical landmark detection on bi-planar radiographs for predicting spinopelvic parameters

INTRODUCTION

Accurate landmark detection is essential for precise analysis of anatomical structures, supporting diagnosis, treatment planning, and monitoring in patients with spinal deformities. Conventional methods rely on laborious landmark identification by medical experts, which motivates automation. The proposed deep learning pipeline processes bi-planar radiographs to determine spinopelvic parameters and Cobb angles without manual supervision.

METHODS

The dataset used for training and evaluation consisted of 555 bi-planar radiographs from un-instrumented patients, which were manually annotated by medical professionals. The pipeline performed a pre-processing step to determine regions of interest, including the cervical spine, thoracolumbar spine, sacrum, and pelvis. For each ROI, a segmentation network was trained to identify vertebral bodies and pelvic landmarks. The U-Net architecture was trained on 455 bi-planar radiographs using binary cross-entropy loss. The post-processing algorithm determined spinal alignment and angular parameters based on the segmentation output. We evaluated the pipeline on a test set of 100 previously unseen bi-planar radiographs, using the mean absolute difference between annotated and predicted landmarks as the performance metric. The spinopelvic parameter predictions of the pipeline were compared to the measurements of two experienced medical professionals using intraclass correlation coefficient (ICC) and mean absolute deviation (MAD).

RESULTS

The pipeline was able to successfully predict the Cobb angles in 61% of all test cases and achieved mean absolute differences of 3.3° (3.6°) and averaged ICC of 0.88. For thoracic kyphosis, lumbar lordosis, sagittal vertical axis, sacral slope, pelvic tilt, and pelvic incidence, the pipeline produced reasonable outputs in 69%, 58%, 86%, 85%, 84%, and 84% of the cases. The MAD was 5.6° (7.8°), 4.7° (4.3°), 2.8 mm (3.0 mm), 4.5° (7.2°), 1.8° (1.8°), and 5.3° (7.7°), while the ICC was measured at 0.69, 0.82, 0.99, 0.61, 0.96, and 0.70, respectively.

CONCLUSION

Despite limitations in patients with severe pathologies and high BMI, the pipeline automatically predicted coronal and sagittal spinopelvic parameters, which has the potential to simplify clinical routines and large-scale retrospective data analysis.

Long-term reoperation risk of thoracic to pelvis instrumentation for spinal deformity: a longitudinal study of 7,062 patients

PURPOSE

To perform a large-scale assessment of reoperation risk among spine deformity patients undergoing thoracic to pelvis surgery.

METHODS

The PearlDiver database was queried for spinal deformity patients (scoliosis, kyphosis, spondylolisthesis, sagittal plane deformity) undergoing at minimum, a T12-pelvis operation (2010-2020). CPT codes identified lumbar arthrodesis procedures that included pelvic fixation and ≥ 7 levels of posterior instrumentation on the same day. Minimum follow-up was 2 years. Reoperations included subsequent arthrodesis, decompression, osteotomy, device insertion, and pelvic fixation procedures. Multivariable regression analysis described associations between variables and reoperation risk.

RESULTS

7,062 patients met criteria. Overall reoperation rate was 23.2%. Reoperation rate at 2- and 5-year was 16.9% and 22.1% respectively. 10-year reoperation-free probability was 73.7% (95% CI: 72.4-74.9%). Multivariable analysis revealed higher reoperation risk for patients with kyphosis and ≥ 13 levels of posterior instrumentation. Patients who received interbody cages had a lower reoperation risk. No association was found between the presence or absence of osteotomy procedures and reoperation risk. Lastly, linear regression analyses revealed no significant relationship between age or ECI and risk for subsequent operations did not independently influence reoperation.

CONCLUSIONS

This study, representing a real-world cohort of over six times the largest current prospective data set, found a 2-year reoperation rate of 17%, similar to previous studies, suggesting study group findings are applicable to a broader population. Preoperative kyphosis and ≥ 13 levels of posterior instrumentation was associated with higher reoperation risk, while the use of interbody cages was protective. Age, medical comorbidities, and osteotomies did not predict reoperations.

How Does Spino-Pelvic Fixation Affect Post-Operative Compensatory Mechanisms in Adult Spinal Deformity?

STUDY DESIGN

Retrospective single-center multi-surgeon cohort study.

OBJECTIVES

Compare the post-operative changes in the compensatory mechanisms of the sagittal balance according to the type of pelvic fixation: S2-Alar-iliac screws (S2AI) vs iliac screws (IS) in patients with Adult spine deformity (ASD).

METHODS

ASD patients who underwent spino-pelvic fixation and remained with a PI-LL >10° mismatch post-operatively were included. Pre-operative and 1-year-follow-up PI, Lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), thoracic kyphosis (TK), femur obliquity angle (FOA), knee flexion angle (KFA) and ankle flexion angle (AFA) were analyzed on EOS imaging. Patients were categorized based on their pelvic fixation type (S2AI vs IS), and the pre-operative to 1-year-post-operative changes (ΔX°) in the compensatory mechanisms were compared between groups.

RESULTS

Patients with S2AI (n = 53) and those with IS (n = 26) screws were comparable at baseline. ΔSS averaged 9.87° in the S2AI compared to 13.2° in the IS (P = .001), whereas the ΔKFA reached 6.01° in the S2AI as opposed to 3.06° in the IS (P = .02). The ΔPT was comparable between both groups (6.35°[S2AI group] vs 5.21°[ISgroup], P = .42). ΔTK, ΔLL, ΔFOA and ΔAFA were comparable between both groups.

CONCLUSION

The type of pelvic fixation impacts significantly the post-operative compensatory mechanisms in patients with ASD. Patients with S2AI screws are more likely to compensate their remaining post-operative PI-LL mismatch through their knees and less likely through their pelvis compared to patients with IS, despite similar changes in PT. This could be explained by an increased SI joint laxity in ASD patient and the lower resistance of the iliac connectors to the junctional mechanical stresses, allowing for sacro-iliac joint motion in patients with IS.

Evaluating variability in decision-making among spine surgeons treating adult spine deformity

BACKGROUND CONTEXT

Significant variability in the management of Adult Spinal Deformity (ASD) has been observed among spine surgeons worldwide. The variability among Canadian spine surgeons, a country with universal public healthcare, remains unknown.

PURPOSE

The study aims to evaluate areas of variability in the perioperative optimization and surgical management of ASD among Canadian spine surgeons.

STUDY DESIGN/SETTING

In this cross-sectional study, 25 Canadian spine surgeons, predominantly orthopedic surgeons (20) and neurosurgeons (5) with varying experience, participated in an online survey focused on Adult Spinal Deformity (ASD).

SAMPLE

The study involved 25 Canadian spine surgeons with varying level of experience, representing both orthopedic and neurosurgical specialities.

OUTCOME MEASURE

The study aimed to evaluate the variability in surgical decision-making and perioperative optimization strategies among Canadian spine surgeons when faced with simulated scenarios of ASD pathologies.

METHODS

The online survey presented 4 vignettes with simulated scenarios of the most common ASD pathologies, including High Grade Spondylolisthesis (HGS), Neglected Adolescent Idiopathic Scoliosis (NAIS), Degenerative Scoliosis (DS), and Flat Back Syndrome (FBS). Questions in the vignettes explored ASD surgical decision-making, while additional questions focused on perioperative optimization. Descriptive statistics were used to analyze multiple-choice responses, and open-text responses were categorized into themes.

RESULTS

Variability was observed in the duration conservative treatment across the 4 ASD cases. Surgeons exhibited variability in the use of preoperative osteoporosis treatment. There was varied use of a dedicated anesthesiology team. Surgical goals varied in HGS and NAIS. The primary surgical method was variable in DS and HGS, the type of osteotomy varied in DS and FBS, and level of fixation varied in HGS and NAIS. Consensus was observed in the use of intraoperative monitoring across of all 4 ASD pathologies, the implementation of a team-based approach, and the selection of the primary surgical goal in DS and FBS.

CONCLUSION

Our cross-sectional study revealed variability among Canadian spine surgeons in the management of ASD, potentially influenced by the uncertain ASD progression, the need for evidence-based nonsurgical guidelines, and insufficient evidence on optimal surgical approaches. These findings will help guide future research to ultimately reduce variability and improve ASD patient management and outcomes.

Utility of Risk Analysis Index for Assessing Morbidity in Patients Undergoing Posterior Spinal Fusion for Adult Spinal Deformity

BACKGROUND

This study investigates the predictive values of the Risk Analysis Index (RAI), the modified 5-item Frailty Index (mFI-5), and advanced age for predicting 30-day extended length of stay (LOS), 30-day complications, and readmissions in patients undergoing posterior spinal fusion (PSF) for adult spinal deformity (ASD).

METHODS

A retrospective cohort study was performed using the 2012-2021 American College of Surgeons National Surgical Quality Improvement Program database. Adults undergoing PSF for ASD were identified using Current Procedural Terminology and International Classification of Diseases codes. Using receiver operating characteristic and multivariable analyses, we compared the discriminative thresholds and independent associations of RAI, mFI-5, and greater patient age for extended LOS, 30-day complications, and readmissions.

RESULTS

In this cohort of 3814 patients, RAI identified 90.7% as Robust, 6.0% as Normal, and 3.3% as Frail/Very frail, while mFI-5 classified 47.1% as Robust, 37.5% as Normal, and 15.3% as Frail/Very frail. Multivariable analysis revealed both RAI and mFI-5 as significant predictors of extended LOS for Normal (RAI: P < 0.001; mFI-5: P = 0.013) and Frail/Very frail patients (RAI: P < 0.001; mFI-5: P = 0.003). Additionally, RAI was a significant predictor of 30-day complication risk for Normal patients (P = 0.005). Furthermore, mFI-5 was a significant predictor of 30-day readmission among Frail/Very frail patients (P = 0.002).

CONCLUSIONS

This study suggests that the utility of RAI and mFI-5 in predicting extended LOS patients undergoing PSF for ASD. RAI was found to be superior to mFI-5 for predicting 30-day readmissions, while mF-5 was greater for 30-day complications. These findings highlight the need for future studies to identify optimal methods in incorporating frailty assessments into preoperative surgical planning and patient discussions.

Surgical Management of Adult Spinal Deformity Patients with Osteoporosis

Adult spinal deformity (ASD) commonly affects older adults, with up to 68% prevalence in those over 60, and is often complicated by osteoporosis, which reduces bone mineral density (BMD) and increases surgical risks. Osteoporotic patients undergoing ASD surgery face higher risks of complications like hardware failure, pseudoarthrosis, and proximal junctional kyphosis (PJK). Medical management with antiresorptive medications (e.g., bisphosphonates, SERMs, and denosumab) and anabolic agents (e.g., teriparatide, abaloparatide, and romosozumab) can improve BMD and reduce complications. While bisphosphonates reduce fracture risk, teriparatide and newer agents like romosozumab show promise in increasing bone density and improving fusion rates. Surgical adaptations such as consideration of age-adjusted alignment, fusion level selection, cement augmentation, and the use of expandable screws or tethers enhance surgical outcomes in osteoporotic patients. Specifically, expandable screws and cement augmentation have been shown to improve fixation stability. However, further research is needed to evaluate the effectiveness of these treatments, specifically in osteoporotic ASD patients.

Analysis of the reliability of KEOPS version 2 for the measurement of coronal and sagittal parameters in spinal deformity

BACKGROUND

The purpose of the study is to evaluate the updated version of this software in patients with various spinal deformity.

METHODS

Sixty patients were included in this study and were divided into three categories: 20 patients with AIS, 20 patients with ASD, and 20 patients having undergone corrective surgery for spinal deformity. The measurements were performed by two senior and two junior orthopedic surgery residents, and were done at two points in time separated by a 3-week interval with the cases being randomized every time to reduce the risk of memory bias. Measured parameters included coronal, sagittal, global alignment parameters, and pelvic parameters.

RESULTS

When assessing the inter- and intra-observer reliability across all the groups of patients, none of the coefficients was smaller than 0.8 with a very high level of agreement. The standard error ranged from 0.7° to 1.5° demonstrating a high level of accuracy. Fairly similar results were seen when the groups were divided into the three categories except for the post-operative groups where a strong and not perfect level of agreement was reported.

CONCLUSION

This is the first study to assess the reproducibility of the new version of KEOPS, showing a very high agreement in all measurements. In the post-operative group, although it showed a strong agreement, the lower performance can be explained by the presence of surgical material making it harder to identify the anatomical landmarks accurately. Nevertheless, we can recommend the usage of this software in a clinical setting.

Dual Versus Single Attending Surgeon Performance of Spinal Deformity Surgery? A Meta-Analysis

BACKGROUND

The inclusion of 2 surgeons in spinal deformity surgery is considered beneficial by some. In fact, select studies indicate advantages such as reduced operation time and blood loss. Another observed decreased patient morbidity with a dual-surgeon approach, attributed to shorter operative times and reduced intraoperative blood losses. Therefore, this meta-analysis will assess the benefits of a having 2 surgeons compared to 1 surgeon during spine surgeries.

METHODS

PubMed, Cochrane, and Google Scholar (page 1-20) were searched till January 2024. The clinical outcomes evaluated were the incidence of adverse events, the rate of transfusion, reoperation, and surgery-related parameters such as operative room time, length of stay (LOS), and estimated blood loss.

RESULTS

Thirteen studies were included. A greater rate of complications was seen in patients operated upon by 1 surgeon (odds ratio = 0.50; 95% confidence intervals [CI]: 0.25-0.99, P = 0.05). Furthermore, operative room time (mean differences = -82.73; 95% CI: -111.42 to -54.03, P < 0.001) and LOS (mean differences = -0.91; 95% CI: -1.12 to -0.71, P < 0.001) were reduced in the dual surgeon scenario. No statistically significant difference was shown in the remaining analyzed outcomes.

CONCLUSIONS

The presence of 2 surgeons in the odds ratiowas shown to reduce complications, operative room time, and LOS. More cost-effectiveness studies are needed in order to substantiate the financial advantages associated with the dual-surgeon approach.

Comprehensive assessment of global spinal sagittal alignment and related normal spinal loads in a healthy population

Abnormal postoperative global sagittal alignment (GSA) is associated with an increased risk of mechanical complications after spinal surgery. Typical assessment of sagittal alignment relies on a few selected measures, disregarding global complexity and variability of the sagittal curvature. The normative range of spinal loads associated with GSA has not yet been considered in clinical evaluation. The study objectives were to develop a new GSA assessment method that holistically describes the inherent relationships within GSA and to estimate the related spinal loads. Vertebral endplates were annotated on radiographs of 85 non-pathological subjects. A Principal Component Analysis (PCA) was performed to derive a Statistical Shape Model (SSM). Associations between identified GSA variability modes and conventional alignment measures were assessed. Simulations of respective Shape Modes (SMs) were performed using an established musculoskeletal AnyBody model to estimate normal variation in cervico-thoraco-lumbar loads. The first six principal components explained 97.96% of GSA variance. The SSM provides the normative range of GSA and a visual representation of the main variability modes. Normal variation relative to the population mean in identified alignment features was found to influence spinal loads, e.g. the lower bound of the second shape mode (SM2-2σ) corresponds to an increase in L4L5-compression by 378.64 N (67.86%). Six unique alignment features were sufficient to describe GSA almost entirely, demonstrating the value of the proposed method for an objective and comprehensive analysis of GSA. The influence of these features on spinal loads provides a normative biomechanical reference, eventually guiding surgical planning of deformity correction in the future.

Can Dynamic Spinal Stabilization Be an Alternative to Fusion Surgery in Adult Spinal Deformity Cases?

BACKGROUND

Rigid stabilization and fusion surgery are widely used for the correction of spinal sagittal and coronal imbalance (SCI). However, instrument failure, pseudoarthrosis, and adjacent segment disease are frequent complications of rigid stabilization and fusion surgery in elderly patients. In this study, we present the results of dynamic stabilization and 2-stage dynamic stabilization surgery for the treatment of spinal SCI. The advantages and disadvantages are discussed, especially as an alternative to fusion surgery.

METHODS

In our study, spinal, sagittal, and coronal deformities were corrected with dynamic stabilization performed in a single session in patients with good bone quality (without osteopenia and osteoporosis), while 2-stage surgery was performed in patients with poor bone quality (first stage: percutaneous placement of screws; second stage: placement of dynamic rods and correction of spinal SCI 4-6 months after the first stage). One-stage dynamic spinal instrumentation was applied to 20 of 25 patients with spinal SCI, and 2-stage dynamic spinal instrumentation was applied to the remaining 5 patients.

RESULTS

Spinal SCI was corrected with these stabilization systems. At 2-year follow-up, no significant loss was observed in the instrumentation system, while no significant loss of correction was observed in sagittal and coronal deformities.

CONCLUSION

In adult patients with spinal SCI, single or 2-stage dynamic stabilization is a viable alternative to fusion surgery due to the very low rate of instrument failure.

CLINICAL RELEVANCE

This study questions the use of dynamic stabilization systems for the treatment of adult degenerative deformities.

LEVEL OF EVIDENCE: 4

Biomechanical analysis of complications following T10-Pelvis spinal fusion: A population based computational study

Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are challenging complications of long fusion constructs for the treatment of adult spinal deformity. The objective of this study is to understand the biomechanical stresses proximal to the upper instrumentation of a T10-pelvis fusion in a large patient cohort. The pre-fusion models were subject-specific thoracolumbar spine models that incorporate the height, weight, spine curvature, and muscle morphology of 250 individuals from the Framingham Heart Study Multidetector CT Study. To create post-fusion models, the subject-specific models were further modified to eliminate motion between the intervertebral joints from T10 to the pelvis. OpenSim analysis tools were used to calculate the medial lateral shear force, anterior posterior shear force, and compressive force on the T9 vertebra during the static postures. Differences between pre-fusion and post-fusion T9 biomechanics were consistent between increased segmental mobility and unchanged segmental mobility conditions. For all static postures, compression decreased (p < 0. 0005). Anterior-posterior shear force significantly increased (p < 0. 0005) during axial twist and significantly increased (p < 0. 0005) during trunk flexion. Medial lateral shear force significantly increased (p < 0. 0005) during axial twist. This computational study provided the first use of subject-specific models to investigate the biomechanics of long spinal fusions. Patients undergoing T10-Pelvis fusion were predicted to have increased shear forces and decreased compressive force at the T9 vertebra, independent of change in segmental mobility. The computational model shows potential for the investigation of spinal fusion biomechanics to reduce the risk of PJK or PJF.

Effectiveness of a two-stage posterior-anterior-posterior surgery using subcutaneously preserved autologous bone grafts for adult spinal deformity: a retrospective observational study

BACKGROUND

To achieve optimal correction of rigid kyphoscoliosis, we developed a novel two-stage posterior-anterior-posterior (PAP) surgery using subcutaneously preserved autologous bone grafts. This study aimed to investigate the effectiveness of two-stage PAP surgery versus single-stage anterior-posterior (AP) surgery.

METHODS

This was a retrospective analysis of patients undergoing combined anterior-posterior long-level fusion for adult spinal deformity (ASD) with a minimum 2-year follow-up. The indications for two-stage PAP surgery were rigid thoracolumbar deformity associated with hypertrophic facet arthritis and/or a large pelvic incidence-lumbar lordosis mismatch of > 25°. In the first stage of PAP surgery, pedicle screw insertion and multilevel Ponte osteotomies were performed. The resected local bone was embedded under sutured fascia. One week later, the embedded bone was retrieved in the right lateral position and used as an autograft for lateral lumbar interbody fusion. Final deformity correction was performed in the prone position.

RESULTS

From January 2018 to April 2021, 12 and 16 patients with ASD underwent two-stage PAP surgery (PAP group) and single-stage AP surgery (AP group), respectively. Although PAP surgery was associated with a significantly longer operation time, the total blood loss volume was significantly less in the PAP group than the AP group. Compared with the AP group, the PAP group showed significantly larger postoperative changes in radiological parameters in the sagittal and coronal planes. The overall complication rate did not differ significantly between the two groups.

CONCLUSION

Two-stage PAP surgery provided effective correction of rigid kyphoscoliosis without increasing blood loss and postoperative complication rates.

Comparative Study of Post-Surgical Outcomes in Pain, Disability, and Health-Related Quality of Life for Adult Spinal Deformity in Patients Aged above and below 75 Years

(1) Background: Adult spinal deformity (ASD) surgery is known to improve clinical and radiological parameters; however, it may also cause more complications in elderly patients. The purpose of this study was to compare the outcomes of ASD surgery, specifically regarding pain, disability, and health-related quality of life (HRQOL) in patients aged 75 years and over and patients aged under 75 years; (2) Methods: A total of 151 patients who underwent ASD surgery between August 2014 and September 2020 were included. Patients were divided into two groups based on whether they are 75 years and over or under. Radiological parameters measured included sagittal vertical axis (SVA), pelvic tilt (PT), and pelvic incidence (PI)- lumbar lordosis (LL). Data were collected 3, 6, and 12 months after surgery; (3) Results: At 12 months postoperatively, visual analog scale (VAS) for low back pain (p = 0.342), Oswestry disability index (ODI) (p = 0.087), and EuroQol 5-Dimensions (EQ-5D) (p = 0.125) did not differ between patients under 75 years and those 75 and above 75 group. PT (p = 0.675), PI-LL (p = 0.948), and SVA (p = 0.108) did not differ significantly 12 months after surgery in the two groups. In the entire patient group, compared to preoperative data, significant improvements were demonstrated for clinical and radiological parameters 12 months after surgery (all p < 0.001). The rate of medical complications did not correlate with age, but the rates of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) did (p = 0.638, p < 0.001, and p = 0.001, respectively); (4) Conclusions: In terms of clinical and radiological improvements, ASD surgery should be considered for patients regardless of whether they are younger than or older than 75 years. The clinical and radiological improvements and the risk of complications and revision surgeries must be considered in ASD patients who are 75 years or older.

Morphological description of sagittal lumbar spinal alignment using curve magnitude, span, and apex-the multiethnic alignment normative study (MEANS)

BACKGROUND CONTEXT

Current definition of lumbar lordosis uses the L1-S1 angle. Prevailing classification of sagittal spinal morphology, derived from a young adult population, classifies the spine into four subtypes defined by their sacral slope (SS) and curve morphology.

PURPOSE

To describe physiological sagittal alignment of the lumbar spine across age groups using three main parameters that dictate the lumbar curve: angular magnitude, span, and apex.

STUDY DESIGN

A large, multicenter, cross-sectional radiographic comparison study.

PATIENT SAMPLE

Four hundred sixty-eight healthy, asymptomatic subjects aged 18 to 80 years from five countries (184 males, 284 females; 98 France, 119 Japan, 79 Singapore, 80 Tunisia, 92 USA, mean age 40.61±14.99 years).

OUTCOME MEASURES

Sagittal lumbar profile subtypes clustered based on lumbar curve angular magnitude (ie, Cobb angle of the lumbar lordosis), span, and apex, and described by sagittal radiographic parameters.

METHODS

Subjects underwent whole-body low-dose EOS stereoradiographs. Comparisons between conventional L1-S1 lumbar lordosis (cLL) and true lumbar lordosis (tLL, defined by the inflection-S1 angle) were conducted. Using the K-means clustering algorithm, lumbar curve angular magnitude, span and apex were used to classify sagittal spinal morphology into subtypes, stratified across age groups. Further univariate and multivariate analyses were conducted to compare radiographic parameters across subtypes, and identify predictors for the lumbar curve's angular magnitude, span and apex.

RESULTS

Mean cLL was -57.27±11.37°, and tLL was -62.62±10.76°. Using tLL, instead of cLL, to describe sagittal spinal morphology, we found significant differences in terms of angular magnitude of the lumbar curve, the median thoracolumbar inflection vertebral level and pelvic incidence-lumbar lordosis mismatch Multivariate analysis found a larger SS, more positive T9 tilt, and more kyphotic T4-T12 predictive for a more lordotic tLL, while a larger overhang distance predicted for a less lordotic tLL (p-values<.001). In addition, a larger T9 tilt, less lordotic L1-L5 and smaller PT were predictors of a more caudal thoracolumbar inflection and lumbar apical vertebral levels (p-values<.001). Sagittal lumbar profiles of subjects age<30 years, 30≤age<60 years and age≥60 years, could be classified into 4, 6, and 3 subtypes, respectively.

CONCLUSIONS

Sagittal lumbar profile subtypes vary across age groups, with more homogenous morphologies at the extremes of ages. Improved understanding of the morphological evolution of sagittal spinal profiles with age in asymptomatic individuals will help guide future individualized surgical treatment.

The Lumbosacral Fractional Curve in Adult Degenerative Scoliosis

Spine surgeons are often faced with a profoundly difficult challenge in surgically treating adult degenerative scoliosis. Deformity correction surgery is complicated by the difficulty in offering extensive surgical corrections to the elderly, complication-prone population it commonly affects. As spine surgeons attempt to offer minimally invasive solutions to this disease process, the need for fusion of the fractional curve at L4, L5, and S1 may be discounted. A treatment strategy to identify, address, and treat the fractional curve with either open or minimally invasive techniques can lead to improved patient outcomes and decrease revision rates in this complicated pathologic process.

Lumbar Disc Degeneration Affects the Risk of Rod Fracture Following PSO; A Finite Element Study

STUDY DESIGN

Finite element (FE) study.

OBJECTIVE

Pedicle subtraction osteotomy (PSO) is a surgical method to correct sagittal plane deformities. In this study, we aimed to investigate the biomechanical effects of lumbar disc degeneration on the instrumentation following PSO and assess the effects of using interbody spacers adjacent to the PSO level in a long instrumented spinal construct.

METHODS

A spinopelvic model (T10-pelvis) with PSO at the L3 level was used to generate 3 different simplified grades of degenerated lumbar discs (mild (Pfirrmann grade III), moderate (Pfirrmann grade IV), and severe (Pfirrmann grade V)). Instrumentation included eighteen pedicle screws and bilateral primary rods. To investigate the effect of interbody spacers, the model with normal disc height was modified to accommodate 2 interbody spacers adjacent to the PSO level through a lateral approach. For the models, the rods' stress distribution, PSO site force values, and the spine range of motion (ROM) were recorded.

RESULTS

The mildly, moderately, and severely degenerated models indicated approximately 10%, 26%, and 40% decrease in flexion/extension motion, respectively. Supplementing the instrumented spinopelvic PSO model using interbody spacers reduced the ROM by 22%, 21%, 4%, and 11% in flexion, extension, lateral bending, and axial rotation, respectively. The FE results illustrated lower von Mises stress on the rods and higher forces at the PSO site at higher degeneration grades and while using the interbody spacers.

CONCLUSIONS

Larger and less degenerated discs adjacent to the PSO site may warrant consideration for interbody cage instrumentation to decrease the risk of rod fracture and PSO site non-union.

Modified frailty index independently predicts morbidity in patients undergoing 3-column osteotomy

PURPOSE

Adult Spinal Deformity (ASD) includes a spectrum of spinal conditions that can be associated with significant pain and loss of function. While 3-column osteotomies have been the procedures of choice for ASD patients, there is also a substantial risk for complications. The prognostic value of the modified 5-item frailty index (mFI-5) for these procedures has not yet been studied. The goal of this study is to evaluate the association of mFI-5 with 30-day morbidity, readmission, and reoperation following a 3-column osteotomy.

METHODS

The National Surgical Quality Improvement Program (NSQIP) database was queried to identify patients undergoing 3-Column Osteotomy procedures from 2011-2019. Multivariate modeling was utilized to assess mFI-5 and other demographic, comorbidity, laboratory, and perioperative variables as independent predictors of morbidity, readmission, and reoperation.

RESULTS

N = 971. Multivariate analysis revealed that mFI-5 = 1 (OR = 1.62, p = 0.015) and mFI-5 ≥ 2 (OR = 2.17, p = 0.004) were significant independent predictors of morbidity. mFI-5 ≥ 2 was a significant independent predictor of readmission (OR = 2.16, p = 0.022) while mFI-5 = 1 was not a significant predictor of readmission (p = 0.053). Frailty did not predict reoperation.

CONCLUSION

Frailty as defined by mFI-5 strongly and independently predicted increased odds of postoperative morbidity for patients undergoing 3-column osteotomy as surgical intervention for ASD. Only mFI-5 ≥ 2 was a significant independent predictor of readmission, while frailty did not predict reoperation. Other variables independently predicted increased and decreased odds of postoperative morbidity, readmission, and reoperation.

LEVEL OF EVIDENCE

III.

Creation and Evaluation of a Severity Classification of Hyperkyphosis and Hypolordosis for Exercise Therapy

The rise in the occurrence of musculoskeletal disorders, such as thoracic hyperkyphosis (THK) or lumbar hypolordosis (LHL), is a result of demographic changes. Exercise therapy is an effective approach that can reduce related disabilities and costs. To ensure successful therapy, an individualized exercise program adapted to the severity of the disorder is expedient. Nevertheless, appropriate classification systems are scarce. This project aimed to develop and evaluate a severity classification focused on exercise therapy for patients with THK or LHL. A multilevel severity classification was developed and evaluated by means of an online survey. Reference limits of spinal shape angles were established by data from video rasterstereography of 201 healthy participants. A mean kyphosis angle of 50.03° and an average lordosis angle of 40.72° were calculated as healthy references. The strength of the multilevel classification consisting of the combination of subjective pain and objective spinal shape factors was confirmed by the survey (70% agreement). In particular, the included pain parameters were considered relevant by 78% of the experts. Even though the results of the survey provide important evidence for further analyses and optimization options of the classification system, the current version is still acceptable as therapeutic support.

Bone microstructure and volumetric bone mineral density in patients with global sagittal malalignment

PURPOSE

Sagittal spinal malalignment often leads to surgical realignment, which is associated with major complications. Low bone mineral density (BMD) and impaired bone microstructure are risk factors for instrumentation failure. This study aims to demonstrate differences in volumetric BMD and bone microstructure between normal and pathological sagittal alignment and to determine the relationships among vBMD, microstructure, sagittal spinal and spinopelvic alignment.

METHODS

A retrospective, cross-sectional study of patients who underwent lumbar fusion for degeneration was conducted. The vBMD of the lumbar spine was assessed by quantitative computed tomography. Bone biopsies were evaluated using microcomputed tomography (μCT). C7-S1 sagittal vertical axis (SVA; ≥ 50 mm malalignment) and spinopelvic alignment were measured. Univariate and multivariable linear regression analysis evaluated associations among the alignment, vBMD and μCT parameters.

RESULTS

A total of 172 patients (55.8% female, 63.3 years, BMI 29.7 kg/m2, 43.0% with malalignment) including N = 106 bone biopsies were analyzed. The vBMD at levels L1, L2, L3 and L4 and the trabecular bone (BV) and total volume (TV) were significantly lower in the malalignment group. SVA was significantly correlated with vBMD at L1-L4 (ρ = -0.300, p < 0.001), BV (ρ = - 0.319, p = 0.006) and TV (ρ = - 0.276, p = 0.018). Significant associations were found between PT and L1-L4 vBMD (ρ = - 0.171, p = 0.029), PT and trabecular number (ρ = - 0.249, p = 0.032), PT and trabecular separation (ρ = 0.291, p = 0.012), and LL and trabecular thickness (ρ = 0.240, p = 0.017). In the multivariable analysis, a higher SVA was associated with lower vBMD (β = - 0.269; p = 0.002).

CONCLUSION

Sagittal malalignment is associated with lower lumbar vBMD and trabecular microstructure. Lumbar vBMD was significantly lower in patients with malalignment. These findings warrant attention, as malalignment patients may be at a higher risk of surgery-related complications due to impaired bone. Standardized preoperative assessment of vBMD may be advisable.

Influence of Handgrip Strength and Paraspinal Muscles' Volume on Clinical Outcomes in the Patients With Each Sagittal Imbalance and Lumbar Spinal Stenosis

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To compare handgrip strength (HGS), paraspinal muscles' (PSM) volume, and their effects on clinical symptom severity between the patients with sagittal imbalance (SI) and symptomatic lumbar spinal stenosis (LSS).

METHODS

A total of 54 paired consecutive patients with SI and LSS were enrolled after propensity score matching. Preoperative HGS, cross-sectional area (CSA) of psoas (PS) and multifidus (MF) muscles, and patient-reported measures, including visual analog scale (VAS) for back/ leg pain, Oswestry Disability Index (ODI), and EuroQOL (EQ-5D) were compared between both groups. Within each SI and LSS group, patient-reported measures were compared between high and low HGS subgroups. The correlation of HGS and CSA of PSMs to patient-reported measures was evaluated.

RESULTS

There was no difference in HGS between 2 groups, however, the CSA of PS and MF muscles in SI group was significantly lower than those in LSS group. Patients with low HGS showed inferior results for ODI and EQ-5D, compared to those with high HGS subgroup in both SI and LSS groups. HGS and CSA of MF muscle were correlated with ODI in both groups.

CONCLUSIONS

There was no significant difference between the SI and LSS groups in HGS, however, PSMs' volume in SI group were significantly lower than those in LSS group. Therefore SI would be associated with loss of localized muscle mass in back area, rather than global skeletal muscle weakness. HGS and PSMs' volume were adversely associated with functional status in SI and LSS patients.

Rod fractures in thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective, multicenter cohort of 160 patients

OBJECTIVE

Previous reports of rod fracture (RF) in adult spinal deformity are limited by heterogeneous cohorts, low follow-up rates, and relatively short follow-up durations. Since the majority of RFs present > 2 years after surgery, true occurrence and revision rates remain unclear. The objectives of this study were to better understand the risk factors for RF and assess its occurrence and revision rates following primary thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis (ASLS) in a prospective series with long-term follow-up.

METHODS

Patient records were obtained from the Adult Symptomatic Lumbar Scoliosis-1 (ASLS-1) database, an NIH-sponsored multicenter, prospective study. Inclusion criteria were as follows: patients aged 40-80 years undergoing primary surgeries for ASLS (Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20 or Scoliosis Research Society-22r ≤ 4.0 in pain, function, and/or self-image) with instrumented fusion of ≥ 7 levels that included the sacrum/pelvis. Patients with and without RF were compared to assess risk factors for RF and revision surgery.

RESULTS

Inclusion criteria were met by 160 patients (median age 62 years, IQR 55.7-67.9 years). At a median follow-up of 5.1 years (IQR 3.8-6.6 years), there were 92 RFs in 62 patients (38.8%). The median time to RF was 3.0 years (IQR 1.9-4.54 years), and 73% occurred > 2 years following surgery. Based on Kaplan-Meier analyses, estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Baseline radiographic, clinical, and demographic characteristics were similar between patients with and without RF. In Cox regression models, greater postoperative pelvic tilt (HR 1.895, 95% CI 1.196-3.002, p = 0.0065) and greater estimated blood loss (HR 1.02, 95% CI 1.005-1.036, p = 0.0088) were associated with increased risk of RF. Thirty-eight patients (61% of all RFs) underwent revision surgery. Bilateral RF was predictive of revision surgery (HR 3.52, 95% CI 1.8-6.9, p = 0.0002), while patients with unilateral nondisplaced RFs were less likely to require revision (HR 0.39, 95% CI 0.18-0.84, p = 0.016).

CONCLUSIONS

This study provides what is to the authors' knowledge the highest-quality data to date on RF rates following ASLS surgery. At a median follow-up of 5.1 years, 38.8% of patients had at least one RF. Estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Greater estimated blood loss and postoperative pelvic tilt were significant risk factors for RF. These findings emphasize the importance of long-term follow-up to realize the true prevalence and cumulative incidence of RF.

Assessment of Cervical and Lumbar Kinematics in Simulated Open and Closed Kinetic Chain

BACKGROUND

The pelvic girdle and spine vertebral column work as a long chain influenced by pelvic tilt. This study aims to assess the effect of open and closed chain anterior pelvic tilt (APT) or posterior pelvic tilt (PPT) on cervical and lumbar spine kinematics using an in vitro cadaveric spine model.

METHODS

Three human cadaveric spines with intact pelvis were suspended with the skull fixed in a metal frame. Optotrak 3-dimensional motion system captured coordinates of pin markers at 24 different points for real-time tracking of cervical and lumbar regions. Additional geometric parameters were measured to calculate pelvic incidence and pelvic tilt. A force-torque digital gauge applied consistent force to standardize the acetabular or sacral axis' APT and PPT during simulated open- and closed-chain movements, respectively.

RESULTS

In closed-chain PPT, significant differences in relative intervertebral decompression were noted between spinal levels C2/C3 (4.85 mm) and C5/C6 (1.26 mm), while compression was noted between L1/L2 (-2.54 mm) and L5/S1 (-11.84 mm) and between L3/L4 (-2.78 mm) and L5/S1 (-11.84 mm) (P < 0.05). Displacement during closed-chain PPT was significantly greater than during open-chain PPT for cervical and lumbar spines. In closed-chain APT, significant differences in relative intervertebral decompression were noted between spinal levels L1/L2 (2.87 mm) and L5/S1 (24.48 mm) and between L3/L4 (2.94 mm) and L5/S1 (24.48 mm) (P < 0.05). Pelvic incidence remained the same as the pelvis tilted anterior and posterior.

CONCLUSIONS

In PPT, open-chain pelvic tilts did not produce as much cervical and lumbar intervertebral displacement compared with closed-chain pelvic tilts. In contrast, APT saw fewer differences between open- and closed-chain tilting. There was a reciprocal relationship between pelvic tilt and sacral slope, producing a constant pelvic incidence throughout all pelvic tilt angles.

CLINICAL RELEVANCE

The results of this study may help determine how a patient's pelvic tilt is causing pain and using that knowledge to guide rehabilitation of stabilizing muscles. The data produced here may also be helpful in determining which rehabilitation exercises may be more difficult or prone to injury for patients with either excessive anterior or posterior pelvic tilt.

Association between sagittal alignment and loads at the adjacent segment in the fused spine: a combined clinical and musculoskeletal modeling study of 205 patients with adult spinal deformity

PURPOSE

Sagittal malalignment is a risk factor for mechanical complications after surgery for adult spinal deformity (ASD). Spinal loads, modulated by sagittal alignment, may explain this relationship. The aims of this study were to investigate the relationships between: (1) postoperative changes in loads at the proximal segment and realignment, and (2) absolute postoperative loads and postoperative alignment measures.

METHODS

A previously validated musculoskeletal model of the whole spine was applied to study a clinical sample of 205 patients with ASD. Based on clinical and radiographic data, pre-and postoperative patient-specific alignments were simulated to predict loads at the proximal segment adjacent to the spinal fusion.

RESULTS

Weak-to-moderate associations were found between pre-to-postop changes in lumbar lordosis, LL (r =  - 0.23, r =  - 0.43; p < 0.001), global tilt, GT (r = 0.26, r = 0.38; p < 0.001) and the Global Alignment and Proportion score, GAP (r = 0.26, r = 0.37; p < 0.001), and changes in compressive and shear forces at the proximal segment. GAP score parameters, thoracic kyphosis measurements and the slope of upper instrumented vertebra were associated with changes in shear. In patients with T10-pelvis fusion, moderate-to-strong associations were found between postoperative sagittal alignment measures and compressive and shear loads, with GT showing the strongest correlations (r = 0.75, r = 0.73, p < 0.001).

CONCLUSIONS

Spinal loads were estimated for patient-specific full spinal alignment profiles in a large cohort of patients with ASD pre-and postoperatively. Loads on the proximal segments were greater in association with sagittal malalignment and malorientation of proximal vertebra. Future work should explore whether they provide a causative mechanism explaining the associated risk of proximal junction complications.

Inventory of Patient-Reported Outcome Measures Used in the Non-Operative Care of Scoliosis: A Scoping Review

It is unclear which patient-reported outcome measures (PROMs) can assess non-operative care for scoliosis. Most existing tools aim to assess the effects of surgery. This scoping review aimed to inventory the PROMs used to assess non-operative scoliosis treatment by population and languages. We searched Medline (OVID) as per COSMIN guidelines. Studies were included if patients were diagnosed with idiopathic scoliosis or adult degenerative scoliosis and used PROMs. Studies without quantitative data or reporting on fewer than 10 participants were excluded. Nine reviewers extracted the PROMs used, the population(s), language(s), and study setting(s). We screened 3724 titles and abstracts. Of these, the full texts of 900 articles were assessed. Data were extracted from 488 studies, in which 145 PROMs were identified across 22 languages and 5 populations (Adolescent Idiopathic Scoliosis, Adult Degenerative Scoliosis, Adult Idiopathic Scoliosis, Adult Spine Deformity, and an Unclear category). Overall, the most used PROMs were the Oswestry Disability Index (ODI, 37.3%), Scoliosis Research Society-22 (SRS-22, 34.8%), and the Short Form-36 (SF-36, 20.1%), but the frequency varied by population. It is now necessary to determine the PROMs that demonstrate the best measurement properties in the non-operative treatment of scoliosis to include in a core set of outcomes.

Fast-track protocols for patients undergoing spine surgery: a systematic review

BACKGROUND CONTEXT

Fast-track is an evidence-based multidisciplinary strategy for pre-, intra-, and postoperative management of patients during major surgery. To date, fast-track has not been recognized or accepted in all surgical areas, particularly in orthopedic spine surgery where it still represents a relatively new paradigm.

PURPOSE

The aim of this review was provided an evidenced-based assessment of specific interventions, measurement, and associated outcomes linked to enhanced recovery pathways in spine surgery field.

METHODS

We conducted a systematic review in three databases from February 2012 to August 2022 to assess the pre-, intra-, and postoperative key elements and the clinical evidence of fast-track protocols as well as specific interventions and associated outcomes, in patients undergoing to spine surgery.

RESULTS

We included 57 full-text articles of which most were retrospective. Most common fast-track elements included patient's education, multimodal analgesia, thrombo- and antibiotic prophylaxis, tranexamic acid use, urinary catheter and drainage removal within 24 hours after surgery, and early mobilization and nutrition. All studies demonstrated that these interventions were able to reduce patients' length of stay (LOS) and opioid use. Comparative studies between fast-track and non-fast-track protocols also showed improved pain scores without increasing complication or readmission rates, thus improving patient's satisfaction and functional recovery.

CONCLUSIONS

According to the review results, fast-track seems to be a successful tool to reduce LOS, accelerate return of function, minimize postoperative pain, and save costs in spine surgery. However, current studies are mainly on degenerative spine diseases and largely restricted to retrospective studies with non-randomized data, thus multicenter randomized trials comparing fast-track outcomes and implementation are mandatory to confirm its benefit in spine surgery.

The postoperative course of mechanical complications in adult spinal deformity surgery

PURPOSE

(a) Describe the time course of each mechanical complication, and (b) compare radiographic measurements and preoperative patient-reported outcome measures (PROMs) among each mechanical complication type.

METHODS

A single-institution case-control study was undertaken of patients undergoing adult spinal deformity (ASD) surgery from 2009-2017. Exposure variables included patient demographics, operative variables, radiographic measurements, and preoperative PROMs, including Oswestry Disability Index (ODI), Numeric Rating Scale Back/Leg-pain scores (NRS-Back/Leg), and EuroQol-5D (EQ-5D). The primary outcomes were occurrence of a mechanical complication and time to complication. Due to overlapping occurrence, rod fracture and pseudarthrosis were grouped into one composite category.

RESULTS

145 patients underwent ASD surgery and were followed for at least 2 years. 30/47 (63.8%) patients with proximal junctional kyphosis (PJK) required reoperation, whereas 27/31 (87.1%) patients with pseudarthrosis/rod fracture required reoperation (63.8% vs. 87.1%, Χ² = -0.23, 95% CI -0.41, -0.05, p = 0.023). Cox regression showed no significant difference in time to reoperation between PJK and rod fracture/pseudarthrosis (HR = 0.97, 95% CI 0.85-1.11, p = 0.686). Distal junctional kyphosis (DJK) (N = 3; 2 reoperation) and implant failures (N = 4; 0 reoperations) were rare. Patients with PJK had significantly lower Hounsfield Units preoperatively compared to those with pseudarthrosis/rod fracture (138.2 ± 43.8 vs. 160.3 ± 41.0, mean difference (MD) =  -22.1, 95% CI -41.8, -2.4, p = 0.028), more prior fusions (51.1% vs. 25.8%, Χ² = 0.253, 95% CI 0.41, 0.46, p = 0.026), fewer instrumented vertebrae (9.2 ± 2.6 vs. 10.7 ± 2.5, MD =  -1.5, 95% CI -2.7, -0.31, p = 0.013), and higher postoperative thoracic kyphosis (TK) (46.3 ± 12.7 vs. 34.9 ± 10.6, MD = 11.4, 95% CI 5.9, 16.9, p < 0.001). Higher postoperative C7 sagittal vertical axis (SVA) did not achieve a significant difference (80.7 ± 72.1 vs. 51.9 ± 57.3, MD = 28.8, 95% CI -1.9, 59.5, p = 0.066). No differences were seen in preoperative PROMs.

CONCLUSION

Patients with pseudarthrosis/rod fracture had a higher reoperation rate compared to those with PJK with similar time to reoperation. Moreover, patients with PJK had higher postoperative TK, lower Hounsfield Units, more prior fusions, and fewer instrumented levels compared to those with pseudarthrosis/rod fracture. The results of this single-institution study suggest that even though mechanical complications are often analyzed as a single group, important differences may exist between them.

LEVEL OF EVIDENCE

III.

What Are the Benefits of Lateral Lumbar Interbody Fusion on the Treatment of Adult Spinal Deformity: A Systematic Review and Meta-Analysis Deformity

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

The purpose of this systematic review and meta-analysis was to compare the efficacy of lateral lumbar interbody fusion (LLIF) combined with posterior spinal fusion (PSF) with that of conventional PSF in the treatment of adult spinal deformity (ASD).

METHODS

A comprehensive literature search was performed for relevant studies in PubMed, EMBASE, Web of Science, and the Cochrane Library. Spinopelvic parameters, surgical data, complications, and clinical outcomes at the last follow-up were compared between patients with ASD who underwent LLIF combined with PSF (LLIF+PSF group) and those who underwent conventional PSF (only-PSF group).

RESULTS

Ten studies, comprising 621 patients with ASD (313 in the LLIF+PSF group and 308 in the only-PSF group), were included. The level of evidence was III for 7 studies and IV for 3 studies. There was no significant difference in the improvement in the visual analog scale score, systemic complication rate, and revision rate between groups. In the LLIF+PSF group, we noted a superior restoration of lumbar lordosis (weighted mean difference [WMD], 9.77; 95% confidence interval [CI] 7.10 to 12.44, P < .001), pelvic tilt (WMD, -2.50; 95% CI -4.25 to -.75, P = .005), sagittal vertical axis (WMD, -21.92; 95% CI -30.73 to -13.11, P < .001), and C7 plumb line-center sacral vertical line (WMD, -4.03; 95% CI -7.52 to -.54, P = .024); a lower estimated blood loss (WMD, -719.99; 95% CI -1105.02 to -334.96, P < .001) while a prolonged operating time (WMD, 104.89; 95% CI 49.36 to 160.43, P < .001); lower incidence of pseudarthrosis (risk ratio [RR], .26; 95% CI .08 to .79, P = .017) while higher incidence of neurologic deficits (RR, 2.04; 95% CI 1.27 to 3.25, P = .003); and a better improvement in Oswestry Disability Index score (WMD, -7.04; 95% CI -10.155 to -3.93, P < .001) and Scoliosis Research Society-22 total score (WMD, .27; 95% CI .11 to .42, P = .001). The level of evidence in this systematic review and meta-analysis was II.

CONCLUSION

Compared with conventional PSF, LLIF combined with PSF was associated with superior restoration of sagittal and coronal alignment, lower incidence of pseudarthrosis, better improvement in quality of life, and less surgical invasiveness in the treatment of ASD, albeit at the cost of prolonged surgical times and substantially high incidence of lower extremity symptoms. Surgeons should weigh the advantages and disadvantages of this procedure, and inform patients about its side effects.

Validation of Adult Spinal Deformity Surgical Outcome Prediction Tools in Adult Symptomatic Lumbar Scoliosis

STUDY DESIGN

A post hoc analysis.

OBJECTIVE

Advances in machine learning (ML) have led to tools offering individualized outcome predictions for adult spinal deformity (ASD). Our objective is to examine the properties of these ASD models in a cohort of adult symptomatic lumbar scoliosis (ASLS) patients.

SUMMARY OF BACKGROUND DATA

ML algorithms produce patient-specific probabilities of outcomes, including major complication (MC), reoperation (RO), and readmission (RA) in ASD. External validation of these models is needed.

METHODS

Thirty-nine predictive factors (12 demographic, 9 radiographic, 4 health-related quality of life, 14 surgical) were retrieved and entered into web-based prediction models for MC, unplanned RO, and hospital RA. Calculated probabilities were compared with actual event rates. Discrimination and calibration were analyzed using receiver operative characteristic area under the curve (where 0.5=chance, 1=perfect) and calibration curves (Brier scores, where 0.25=chance, 0=perfect). Ninety-five percent confidence intervals are reported.

RESULTS

A total of 169 of 187 (90%) surgical patients completed 2-year follow up. The observed rate of MCs was 41.4% with model predictions ranging from 13% to 68% (mean: 38.7%). RO was 20.7% with model predictions ranging from 9% to 54% (mean: 30.1%). Hospital RA was 17.2% with model predictions ranging from 13% to 50% (mean: 28.5%). Model classification for all three outcome measures was better than chance for all [area under the curve=MC 0.6 (0.5-0.7), RA 0.6 (0.5-0.7), RO 0.6 (0.5-0.7)]. Calibration was better than chance for all, though best for RA and RO (Brier Score=MC 0.22, RA 0.16, RO 0.17).

CONCLUSIONS

ASD prediction models for MC, RA, and RO performed better than chance in a cohort of adult lumbar scoliosis patients, though the homogeneity of ASLS affected calibration and accuracy. Optimization of models require samples with the breadth of outcomes (0%-100%), supporting the need for continued data collection as personalized prediction models may improve decision-making for the patient and surgeon alike.

Treatment of patients with degenerative deformities of the lumbar spine using MIS technologies: analysis of 5-year results

Objective. To analyze the results of the use of minimally invasive technologies in the treatment of patients with degenerative deformity of the lumbar spine.

Material and Methods. Design: Single-center, non-randomized continuous retrospective cohort study. The level of evidence is 3b (UK Oxford, version 2009). A total of 57 patients (10 men and 47 women) were operated for degenerative scoliosis of the lumbar spine using minimally invasive techniques. The quality of life indicators using ODI, SF-36, VAS, as well as linear and angulometric parameters of the spine were studied.

Results. The age of patients ranged from 37 to 81 years (62/62 [55; 67], hereinafter the data format is mean/median [1; 3rd quartile]). In the postoperative period, patients operated on with MIS techniques showed a statistically significant decrease in pain by 4.3/4.0 [3; 6] points in the lumbar spine, and by 4.3/4.0 [3; 6] points in the legs. Quality of life indicators according to ODI improved by 24/23 [19;  29], and the level of functional adaptation according to the SF-36 questionnaire – by 18/18 [14; 21] in terms of physical parameters and by 18/20 [16; 23] in terms of mental parameters. The deformity angle in the frontal plane according to Cobb decreased by 12.9°/13.0° [10°; 17°], lumbar lordosis changed by 3.3°/2.0° [-1°; 7°], segmental angle L4–S1 – by 1.0°/0.0° [-5°; 7°], and SVA changed by -7.5/-2.0 [-29; 15] mm. As a result of minimally invasive surgical intervention, a good clinical result was obtained in correcting the scoliotic deformity angle from 17.5°/16.0° [11°; 22°] to 4.6°/4.0° [1°; 7°].

Conclusion. The study showed the effectiveness of minimally invasive surgical treatment of degenerative scoliosis of the lumbar spine with short-segment fixation, which allowed obtaining satisfactory clinical results in 93 % of cases with a minimum number of complications (7 %).

Cervical Inclination Angle: Normative Values in an Adult Multiethnic Asymptomatic Population

OBJECTIVE

The role of the craniocervical complex in spinal sagittal alignment has rarely been analyzed but it may play a fundamental role in postoperative mechanical complications. The aim of the study is to analyze the normative value of the cervical inclination angle (CIA) in an adult asymptomatic multiethnic population.

METHODS

Standing full-spine EOS of adult asymptomatic volunteers from 5 different countries were analyzed. The CIA was analyzed globally and then in each decade of life. Different ethnicities were compared. Comparisons between different groups was performed using a t-test and statistical significance was considered with a p-value < 0.05.

RESULTS

EOS of 468 volunteers were analyzed. The global mean CIA was 80.2° with a maximum difference of 9° between T1 and T12 (p < 0.001). The CIA remains constant until 60 years old then decreases significantly passing from a mean value before 20 years old of 82.25° to 73.65° after 70 years old. A statistically significant difference was found between the Arabics and other ethnicities with the formers having an inferior CIA: this was related to a mean older age (p < 0.05) and higher body mass index (p < 0.05) in the Arabics.

CONCLUSION

The CIA remains constant until 60 years old and then reduces slightly but never under 70°. This angle is helpful to evaluate the lever arm at the upper instrumented vertebra after an adult spinal deformity surgery and could predict the occurrence of a proximal junctional kyphosis when its value is lower than normal. Further clinical studies must confirm this theory.

Biomechanical Comparison of Multilevel Lumbar Instrumented Fusions in Adult Spinal Deformity According to the Upper and Lower Fusion Levels: A Finite Element Analysis

Multilevel lumbar fusion with posterior pedicle screw fixation is a widely performed surgical procedure for the management of adult spinal deformity. However, there has not been a comprehensive biomechanical study on the different types of fusion levels in terms of stability and possible complications. We aimed to investigate the biomechanical properties of multilevel lumbar fusion according to different types of upper and lower fusion levels. Six different types of fusions were performed using three-dimensional finite element models. Type A and B referred to the group of which upper fusion level was L1 and T10, respectively. Subtype 1, 2, and 3 referred to the group of which lower fusion level was L5, S1, and ilium, respectively (A1, L1-L5; A2, L1-S1; A3, L1-ilium; B1, T10-L5; B2, T10-S1; B3, T10-ilium). Flexion, extension, axial rotation, and lateral bending moments were applied, and the risk of screw loosening and failure and adjacent segment degeneration (ASD) was analyzed. Stress at the bone-screw interface of type B3 was lowest in overall motions. The risk of screw failure showed increasing pattern as the upper and lower levels extended in all motions. Proximal range of motion (ROM) increased as the lower fusion level changed from L5 to S1 and the ilium. For axial rotation, type B3 showed higher proximal ROM (16.2°) than type A3 (11.8°). In multilevel lumbar fusion surgery for adult spinal deformity, adding iliac screws and increasing the fusion level to T10-ilium may lower the risk of screw loosening. In terms of screw failure and proximal ASD, however, T10-ilium fusion has a higher potential risk compared with other fusion types. These results will contribute for surgeons to provide adequate patient education regarding screw failure and proximal ASD, when performing multilevel lumbar fusion.

Systematic review and meta-analysis for the impact of rod materials and sizes in the surgical treatment of adult spine deformity

PURPOSE

To assess clinical and safety outcomes associated with different rod materials and diameters in adult spinal deformity (ASD) surgery.

METHODS

A systematic literature review and meta-analysis evaluated ASD surgery using pedicle screw fixation systems with rods of different materials and sizes. Postoperative outcomes (i.e., Cobb, sagittal vertical axis, and pelvic tilt angle) and complications (i.e., pseudarthrosis and rod breakage) were assessed. Random effects models (REMs) pooled data for outcomes reported in ≥ 2 studies.

RESULTS

Among 50 studies evaluating ASD surgery using pedicle screw fixation systems, 17 described rod material/diameter. Postoperative outcomes did not statistically differ between cobalt-chromium (CoCr) vs. titanium (Ti) rods (n = 2 studies; mean [95% confidence interval (CI)] sagittal vertical axis angle: CoCr 37.00° [18.58°-55.42°] and Ti 32.58° [24.62°-40.54°]; mean [95% CI] pelvic tilt angle: CoCr 26.20° [22.87°-29.53°] and Ti 20.15° [18.0°-22.31°]). The pooled proportion (95% CI) of pseudarthrosis was 15% (7-22%) for CoCr and 12% (- 8-32%) for stainless steel (SS) (n = 2 studies each; Chi2 = 0.07, p = 0.79). The pooled proportion (95% CI) of broken rods was 12% (1-22%) for Ti (n = 3 studies) and 10% (2-19) for CoCr (n = 1 study). Among 6.0-6.35 mm rods, the pooled (95% CI) postoperative Cobb angle (n = 2) was 12.01° (9.75°-14.28°), sagittal vertical axis angle (n = 4) was 35.32° (30.02°-40.62°), and pelvic tilt angle was 21.11° (18.35°-23.86°).

CONCLUSIONS

For ASD patients undergoing posterior fixation and fusion, there are no statistically significant differences in postoperative outcomes or complications among rods of varying materials and diameters. Benchmark postsurgical outcomes and complication rates by rod material and diameter are provided.

LEVEL OF EVIDENCE

III.

Adult Spinal Deformity: A Comprehensive Review of Current Advances and Future Directions

Owing to rapidly changing global demographics, adult spinal deformity (ASD) now accounts for a significant proportion of the Global Burden of Disease. Sagittal imbalance caused by age-related degenerative changes leads to back pain, neurological deficits, and deformity, which negatively affect the health-related quality of life (HRQoL) of patients. Along with the recognized regional, global, and sagittal spinopelvic parameters, poor paraspinal muscle quality has recently been acknowledged as a key determinant of the clinical outcomes of ASD. Although the Scoliosis Research Society-Schwab ASD classification system incorporates the radiological factors related to HRQoL, it cannot accurately predict the mechanical complications. With the rapid advances in surgical techniques, many surgical options for ASD have been developed, ranging from minimally invasive surgery to osteotomies. Therefore, structured patient-specific management is important in surgical decision-making, selecting the proper surgical technique, and to prevent serious complications in patients with ASD. Moreover, utilizing the latest technologies such as robotic-assisted surgery and machine learning, should help in minimizing the surgical risks and complications in the future.

Complications in the Elderly Population Undergoing Spinal Deformity Surgery: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic Review and Meta-Analysis.

OBJECTIVES

The elderly have an increased risk of perioperative complications for Adult Spinal Deformity (ASD) corrections. Stratification of these perioperative complications based on risk type and specific risk factors, however, remain unclear. This paper will systematically review perioperative risk factors in the elderly undergoing ASD correction stratified by type: medical, implant-related, proximal junctional kyphosis (PJK), and need for revision surgery.

METHODS

A systematic review was performed using the PRISMA guidelines. A query of PubMed was performed to identify publications pertinent to ASD in the elderly. Publications included in this review focused on patients ≥65 years old who underwent operative management for ASD to assess for risk factors of perioperative complications.

RESULTS

A total of 734 unique citations were screened resulting in ten included articles for this review. Pooled incidence of perioperative complications included medical complications (21%), implant-related complications (16%), PJK (29%), and revision surgery (13%). Meta-analysis calculated greater preoperative PT (WMD 2.66; 95% Cl .36-4.96; P = .02), greater preoperative SVA (WMD 2.24; 95% Cl .62-3.86; P = .01), and greater postoperative SVA (WMD .97; 95% Cl .03-1.90; P = .04) to significantly correlate with development of PJK with no evidence of publication bias or concerns in study heterogeneity.

CONCLUSIONS

There is a paucity of literature describing perioperative complications in the elderly following ASD surgery. Appropriate understanding of modifiable risk factors for the development of medical and implant-related complications, proximal junctional kyphosis, and revision surgeries presents an opportunity to decrease morbidity and improve patient outcomes.

Application of 3D printed models in the surgical treatment of spinal deformity

OBJECTIVE

To test if preoperative planning with 3 dimensional (3D)-printed spine models can increase the effectiveness and safety of spinal deformity surgery.

METHODS

A total of 53 patients who were treated in our center for spinal deformities from January 2010 to January 2018 were included in the current study. They were divided into two groups based on whether 3D-printed models were used in the surgical planning. A total of 28 patients who were treated with 3D-printed models were assigned to the experimental group, and 25 patients who were treated with conventional methods were assigned to the control group. Duration of surgery, intraoperative hemorrhage, incidence of surgery related complications, Oswestry disability index (ODI), visual analogue scale (VAS), and Cobb's angle were compared between the two groups before and after surgery.

RESULTS

There were significant differences in the duration of surgery, intraoperative hemorrhage and intraoperative x-ray exposure between the two groups (P<0.01). Cobb's angle was smaller in the experimental group than in the control group when measured three days and a year after surgery (P<0.01). Although there was no significant difference between the experimental and control groups (P>0.05), Oswestry disability index and VAS pain scores were lower a month and a year after the surgery than before the surgery (P<0.01).

CONCLUSION

Surgical planning using 3D-printed spine models can decrease the operation time, intraoperative hemorrhage, and x-ray exposure, and help achieve satisfactory structural restoration in patients with severe spinal deformity.

Demographic Predictors of Treatment and Complications for Adult Spinal Deformity: An Analysis of the National Inpatient Sample

PURPOSE

To examine the role of demographics on surgical management and inpatient complications in patients with spinal deformity between 2010 and 2014 via retrospective analysis.

METHODS

Data were obtained from the National Inpatient Sample (NIS). International Classification of Diseases 9th revision codes were used to identify patients with a primary diagnosis of adult spinal deformity (ASD). Multivariable Poisson regression analyses were used to determine whether any individual demographic variables were predictive of surgical management, surgical complexity, postoperative complications and revision operations.

RESULTS

17,433 patients were identified for analysis. Surgical intervention was performed for 94.5% of patients with a primary diagnosis of ASD. Patients at urban teaching hospitals were the most likely to receive surgery (OR= 2.13; 95% CI 1.51-2.95; p < 0.001) relative to rural patients. Female patients were the majority undergoing surgery and were more likely to receive a complication or require a revision when controlling for surgical complexity. Medicare patients were the least likely to undergo surgery and the most likely to receive complex fusion when undergoing an operation. Medicare patients were the least likely to experience complications (OR=0.89; 95% CI 0.80-0.98; p = 0.022) after adjusting for surgical complexity. With regards to race and ethnicity, Hispanics had a decreased likelihood of receiving a revision surgery.

CONCLUSION

There were substantial differences in rates of surgical management, postoperative complications, and revisions among individuals of different demographics including sex, insurance status, ethnicity and hospital teaching status. Further research evaluating the effect of demographics in spine surgery is warranted to fully understand their influence on patient outcomes.

Modifiable Patient Factors Demonstrate No Increased Risk for 30-Day Complication Rate for Elective 1-2 Level Posterior Lumbar Fusion Surgery: A Comparison Between a National Database and Local Registry

BACKGROUND

While national databases provide large datasets that can be used to understand trends over time, their correlation with prospectively collected data from local registries has not been established. The purpose of the study was to compare differences in patient demographics and adverse events for patients undergoing elective posterior spinal fusion (PSF) between a national database and institutional registry.

METHODS

A retrospective chart review was performed. A total of 14,618 patients (13,678 patients from the National Surgical Quality Improvement Program [NSQIP] database and 940 patients from the institutional registry) who underwent elective 1- to 2-level PSF were included in the study. Preoperative patient demographics and comorbidities of each cohort were compared. In addition, postoperative 30-day complications and readmission were collected. A multivariate analysis was performed to examine for differences in risk factors for 30-day adverse events between the 2 cohorts.

RESULTS

A total of 13,678 patients from the NSQIP database and 940 patients from the institutional cohort were included for analysis. Mean age was similar between patient cohorts (60.8 ± 13.1NSQIP vs 58.8 ± 12.9registry), with NSQIP having significantly more patients over the age of 65 (41.4% vs 33.2%, P < 0.001). Overall complication rate was similar between NSQIP (6.8%) and the institutional registry (8.4%). Both found age and female sex to be significant predictors of 30-day adverse events, while obesity, hypertension, and smoking were only found to be predictive in the NSQIP database.

CONCLUSIONS

Age and female sex were found to be independent risk factors for 30-day adverse events between both cohorts, while only NSQIP found modifiable comorbidities to be significant predictors. Although large databases allow for trends in quality over time, subtleties in practice variation and data collection methods at the individual institution level need to be considered when generalizing findings, especially as it pertains to modifiable factors.

CLINICAL RELEVANCE

Quality metrics and risk factors for patient outcomes are often derived from national databases. This study highlights the differences between study results when outcomes are derived from an institutional registry compared to a national database.

LEVEL OF EVIDENCE: 3

Preoperative Malnutrition-Associated Spinal Malalignment with Patient-Reported Outcome Measures in Adult Spinal Deformity Surgery: A 2-Year Follow-Up Study

Introduction

Malnutrition could lead to additional medical complications, and the prognostic nutrition index (PNI) is evaluated to assess the nutritional status of patients. However, the midterm postoperative outcomes of malnutrition in patients with adult spinal deformity (ASD) are unclear. This study aims to investigate postoperative midterm spinal alignment and patients' reported outcome measures (PROMs) in malnourished patients with ASD.

Methods

This study recruited 303 ASD patients who underwent surgery. Adult patients ≥50 years old were categorized into the PNI <50 (L group) and the PNI ≥50 (H group) groups. Demographic data, medical complications, mechanical complications, radiographic parameters, Oswestry Disability Index (ODI), and Scoliosis Research Society-22 (SRS-22) were analyzed.

Results

In this study, 303 patients participated, with 132 and 171 patients in the L and H groups, respectively. Significant differences were noted between the L and H groups in body mass index (22.5 vs. 23.6 kg/m², p=0.011), autoimmune disease (9.8% vs. 2.3%, p=0.005), and total number of medical complications (47.7% vs. 33.3%, p=0.011). The T1 slope was significantly higher in the L group than in the H group preoperatively (36.5 vs. 32.8°, p=0.042). However, no significant differences were noted in mechanical complications, ODI, SRS-22 scores, or radiographic parameters 2 years postoperatively between the L and H groups, except for the sagittal vertical axis (73.1 vs. 55.7 mm, p=0.014).

Conclusions

No significant difference was noted in the incidence of mechanical complications and PROMs 2 years postoperatively. Malnourished status was related to medical complications and global malalignment. However, good surgical outcomes can be expected even for malnourished patients.

Complex Wound Closure in Adult Spinal Deformity Surgery Reduces Complications in High-Risk Patients

BACKGROUND

Adult spinal deformity (ASD) surgery is becoming increasingly prevalent. Soft tissue defects arising from revision closure and impaired healing can predispose to wound complications including dehiscence and infection. Soft tissue coverage with local muscle flaps has been shown to minimize wound complications in high-risk patients. In this study we evaluate the role of complex wound closure in preventing wound complications in high-risk spinal deformity patients.

METHODS

The authors retrospectively reviewed charts of patients who underwent ASD surgery. Patients were stratified into muscle flap advancement (by neurosurgery or plastic surgery) closure versus primary approximation by neurosurgery. Relevant patient and operative factors were collected and summarized using descriptive statistics. Outcomes of interest included wound complication and revision surgery.

RESULTS

Ninety-four cases met inclusion criteria including 56 wounds closed by neurosurgery and 38 wounds closed by plastic surgery (PRS). Of the neurosurgery wounds, 31 and 25 were closed by primary approximation and muscular flap advancement, respectively. Patients operated on by PRS were higher risk than all patients operated on only by neurosurgery (P = 0.0037) but were not significantly higher risk than the neurosurgery performed flap cohort (P = 0.4914). In subgroup analysis, despite similar levels of risk, the PRS population experienced lower rates of any wound complication (P = 0.028) and specifically dehiscence (P = 0.029) compared with the neurosurgery performed flap closure cohort.

CONCLUSIONS

Prophylactic involvement of plastic surgery in ASD surgery wound closure may improve wound outcomes in higher risk patients. A multidisciplinary approach with plastic and spine surgeons may lessen the risk of wound complications in high-risk spine surgeries.

Systemic Risk Factors for Adult Spinal Deformity (ASD): A Retrospective Analysis of 48 Patients

Introduction: Adult spinal deformity (ASD) results in significant patient morbidity and burden to quality of life. The degree to which systemic risk factors and comorbidities that contribute to ASD affect specific spinopelvic parameters is not well-documented. We determine the extent to which preoperative risk factors may contribute to spinopelvic parameters associated with ASD.

Methods: Retrospective single-center study of 48 patients with ASD. Analysis of variance (ANOVA) linear regression analysis was performed to evaluate correlation between systemic comorbidities (obesity, arterial hypertension (HTN), hyperlipidemia (HLD), cardiomyopathy, diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), and asthma) and the following radiographic parameters: pelvic incidence (PI), lumbar lordosis (LL), C7 sagittal vertical axis (C7SVA), and the T10-L2 sagittal cobb angle.

Results: A total of 48 patients were included with mean C7SVA of 79.6 mm (SD: 63, range: 43-254), mean LL of 32.9° (SD: 15.9, range: -14 to 78), T10-L2 sagittal cobb angle of 3° (SD: 12.7, range: -24 to 30), and PI was 49° (SD: 10.7, range: 21 to 77). Only DM correlated with sagittal imbalance with high C7SVA and PI-LL mismatch. The beta coefficient for DM and preoperative C7SVA was 0.49, t=3.16, p=0.003, preoperative PI-LL mismatch standardized beta coefficient was -0.4, t=-2.38, p=0.022, and preoperative T10-L2 sagittal cobb standard beta coefficient was -0.07, t=-0.46, p=0.645. No significant correlations were found for asthma, COPD, HTN, HLD, or cardiomyopathy.

Conclusions: Diagnosis of DM was found to correlate with pathologic C7SVA and significant PI-LL mismatch associated with ASD. HTN, HLD, cardiomyopathy, obesity, and pulmonary disease did not correlate with radiographic findings of sagittal imbalance.

Adult Spinal Deformity Surgery and Frailty: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

Adult spinal deformity (ASD) can be a debilitating condition with a profound impact on patients' health-related quality of life (HRQoL). Many reports have suggested that the frailty status of a patient can have a significant impact on the outcome of the surgery. The present review aims to identify all pre-operative patient-specific frailty markers that are associated with postoperative outcomes following corrective surgery for ASD of the lumbar and thoracic spine.

METHODS

A systematic review of the literature was performed to identify findings regarding pre-operative markers of frailty and their association with postoperative outcomes in patients undergoing ASD surgery of the lumbar and thoracic spine. The search was performed in the following databases: PubMed, Embase, Cochrane and CINAHL.

RESULTS

An association between poorer performance on frailty scales and worse postoperative outcomes. Comorbidity indices were even more frequently employed with similar patterns of association between increased comorbidity burden and postoperative outcomes. Regarding the assessment of HRQoL, worse pre-operative ODI, SF-36, SRS-22 and NRS were shown to be predictors of post-operative complications, while ODI, SF-36 and SRS-22 were found to improve post-operatively.

CONCLUSIONS

The findings of this review highlight the true breadth of the concept of "frailty" in ASD surgical correction. These parameters, which include frailty scales and various comorbidity and HRQoL indices, highlight the importance of identifying these factors preoperatively to ensure appropriate patient selection while helping to limit poor postoperative outcomes.

The Incidence, Risk Factors, and Complications Associated With Surgical Delay in Multilevel Fusion for Adult Spinal Deformity

STUDY DESIGN

Retrospective database review.

OBJECTIVES

The incidence and risk factors for surgical delay of multilevel spine fusion for adult spinal deformity (ASD), and the complications corresponding therewith, remain unknown. The objectives of this study are to assess the incidence and risk factors for unexpected delay of elective multilevel spinal fusions on the date of surgery as well as the postoperative complications associated with these delays.

METHODS

We conducted a retrospective review of the ACS-NSQIP database on patients undergoing elective spinal instrumentation of greater than 7 levels for ASD between the years 2005 and 2015. Preoperative risk factors for delay and postoperative complications were compared between the cohorts of patients with and without surgical delays.

RESULTS

Multivariate analysis of 1570 (15.6%) patients identified advanced age, male sex, American Society of Anesthesiologists (ASA) Class 4, and history of smoking as independent risk factors for delay. Patients experiencing surgical delay demonstrated longer operative times, increased intraoperative bleeding, longer hospitalizations, and significantly higher rates of postoperative complications. Patients experiencing delay demonstrated an almost 7-fold increase in mortality rate (3.4% vs 0.5%, P < .001).

CONCLUSIONS

Delays in elective surgical care for spinal deformity are negatively related to patient outcomes. Advanced age, male sex, increased ASA class, and a history of smoking cigarettes place patients at risk for surgical delay of multilevel spinal fusion. Patients experiencing surgical delay are at higher risk for postoperative complications, including a 7-fold increase in mortality. These findings suggest that ASD surgery should be postponed in patients experiencing a delay, until modifiable risk factors can be medically optimized, and perhaps postponed indefinitely in those with nonmodifiable risk factors.