Highest Achievable Outcomes for Adult Spinal Deformity Corrective Surgery: Does Frailty Severity Exert a Ceiling Effect?

STUDY DESIGN: Retrospective Single-Center Study. OBJECTIVE: To assess the influence of frailty on optimal outcome following ASD corrective surgery. SUMMARY OF BACKGROUND DATA: Frailty is a determining factor in outcomes after ASD surgery and may exert a ceiling effect on best possible outcome. METHODS: ASD patients with frailty measures, baseline and 2-year ODI included. Frailty was classified as Not Frail (NF), Frail (F) and Severely Frail (SF) based on the modified Frailty Index, then stratified into quartiles based on 2-year ODI improvement (most improved designated "Highest"). Logistic regression analyzed relationships between frailty and ODI score and improvement, maintenance, or deterioration. A Kaplan-Meier survival curve was used to analyze differences in time to complication or reoperation. RESULTS: 393 ASD patients were isolated (55.2% NF, 31.0% F, and 13.7% SF), then classified as 12.5% NF-Highest, 17.8% F-Highest, and 3.1% SF-Highest. The SF-group had the highest rate of deterioration (16.7%, P=0.025) at the second postoperative year but the groups were similar in improvement (NF: 10.1%, F: 11.5%, SF: 9.3%, P=0.886). Improvement of SF patients was greatest at 6 months (ΔODI of -22.6±18.0, P<0.001) but NF and F patients reached maximal ODI at 2 years (ΔODI of -15.7±17.9 and -20.5±18.4, respectively). SF patients initially showed the greatest improvement in ODI (NF: -4.8±19.0, F: -12.4±19.3, SF: -22.6±18.0 at 6 months, P<0.001). A Kaplan-Meier survival curve showed a trend of less time to major complication or reoperation by 2 years with increasing frailty (NF: 7.5±0.381 years, F: 6.7±0.511 years, SF: 5.8±0.757 years; P=0.113). CONCLUSIONS: Increasing frailty had a negative effect on maximal improvement, where severely frail patients exhibited a parabolic effect with greater initial improvement due to higher baseline disability, but reached a ceiling effect with less overall maximal improvement. Severe frailty may exert a ceiling effect on improvement and impair maintenance of improvement following surgery. LEVEL OF EVIDENCE: III.

Factors Influencing Maintenance of Alignment and Functional Improvement Following Adult Spinal Deformity Surgery: A 3-Year Outcome Analysis.

STUDY DESIGN: This was a retrospective review. OBJECTIVE: To assess the factors contributing to durability of surgical results following adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND: Factors contributing to the long-term sustainability of ASD correction are currently undefined. MATERIALS AND METHODS: Operative ASD patients with preoperatively (baseline) and 3-year postoperatively radiographic/health-related quality of life data were included. At 1 and 3 years postoperatively, a favorable outcome was defined as meeting at least three of four criteria: (1) no proximal junctional failure or mechanical failure with reoperation, (2) best clinical outcome (BCO) for Scoliosis Research Society (SRS) (≥4.5) or Oswestry Disability Index (ODI) (<15), (3) improving in at least one SRS-Schwab modifier, and (4) not worsening in any SRS-Schwab modifier. A robust surgical result was defined as having a favorable outcome at both 1 and 3 years. Predictors of robust outcomes were identified using multivariable regression analysis with conditional inference tree for continuous variables. RESULTS: We included 157 ASD patients in this analysis. At 1 year postoperatively, 62 patients (39.5%) met the BCO definition for ODI and 33 (21.0%) met the BCO for SRS. At 3 years, 58 patients (36.9%) had BCO for ODI and 29 (18.5%) for SRS. Ninety-five patients (60.5%) were identified as having a favorable outcome at 1 year postoperatively. At 3 years, 85 patients (54.1%) had a favorable outcome. Seventy-eight patients (49.7%) met criteria for a durable surgical result. Multivariable adjusted analysis identified the following independent predictors of surgical durability: surgical invasiveness >65, being fused to S1/pelvis, baseline to 6-week pelvic incidence and lumbar lordosis difference >13.9°, and having a proportional Global Alignment and Proportion score at 6 weeks. CONCLUSIONS: Nearly 50% of the ASD cohort demonstrated good surgical durability, with favorable radiographic alignment and functional status maintained up to 3 years. Surgical durability was more likely in patients whose reconstruction was fused to the pelvis and addressed lumbopelvic mismatch with adequate surgical invasiveness to achieve full alignment correction.

Risk of spinal surgery among individuals who have been re-vascularized for coronary artery disease.

HYPOTHESIS: Revascularization is a more effective intervention to reduce future postop complications. METHODS: Patients undergoing elective spine fusion surgery were isolated in the PearlDiver database. Patients were stratified by having previous history of vascular stenting (Stent), coronary artery bypass graft (CABG), and no previous heart procedure (No-HP). Means comparison tests (chi-squared and independent samples t-tests, as appropriate) compared differences in demographics, diagnoses, and comorbidities. Binary logistic regression assessed the odds of 30-day and 90-day postoperative (postop) complications associated with each heart procedure (Odds Ratio [95 % confidence interval]). Statistical significance was set p < 0.05. RESULTS: 731,173 elective spine fusion patients included. Overall, 8,401 pts underwent a CABG, 24,037 pts Stent, and 698,735 had No-HP prior to spine fusion surgery. Compared to Stent and No-HP patients, CABG patients had higher rates of morbid obesity, chronic kidney disease, and diabetes (p < 0.001 for all). Meanwhile, stent patients had higher rates of PVD, hypertension, and hyperlipidemia (all p < 0.001). 30-days post-op, CABG patients had significantly higher complication rates including pneumonia, CVA, MI, sepsis, and death compared to No-HP (all p < 0.001). Stent patients vs. No-HF had higher 30-day post-op complication rates including pneumonia, CVA, MI, sepsis, and death. Furthermore, adjusting for age, comorbidities, and sex Stent was significantly predictive of a MI 30-days post-op (OR: 1.90 [1.53-2.34], P < 0.001). Additionally, controlling for levels fused, stent patients compared to CABG patients had 1.99x greater odds of a MI within 30-days (OR: 1.99 [1.26-3.31], p = 0.005) and 2.02x odds within 90-days postop (OR: 2.2 [1.53-2.71, p < 0.001). CONCLUSION: With regards to spine surgery, coronary artery bypass graft remains the gold standard for risk reduction. Stenting does not appear to minimize risk of experiencing a post-procedure cardiac event as dramatically as CABG.

Cost Benefit of Implementation of Risk Stratification Models for Adult Spinal Deformity Surgery.

STUDY DESIGN/SETTING: Retrospective cohort study. OBJECTIVE: Assess the extent to which defined risk factors of adverse events are drivers of cost-utility in spinal deformity (ASD) surgery. METHODS: ASD patients with 2-year (2Y) data were included. Tertiles were used to define high degrees of frailty, sagittal deformity, blood loss, and surgical time. Cost was calculated using the Pearl Diver registry and cost-utility at 2Y was compared between cohorts based on the number of risk factors present. Statistically significant differences in cost-utility by number of baseline risk factors were determined using ANOVA, followed by a generalized linear model, adjusting for clinical site and surgeon, to assess the effects of increasing risk score on overall cost-utility. RESULTS: By 2 years, 31% experienced a major complication and 23% underwent reoperation. Patients with ≤2 risk factors had significantly less major complications. Patients with 2 risk factors improved the most from baseline to 2Y in ODI. Average cost increased by $8234 per risk factor (R2 = .981). Cost-per-QALY at 2Y increased by $122,650 per risk factor (R2 = .794). Adjusted generalized linear model demonstrated a significant trend between increasing risk score and increasing cost-utility (r2 = .408, P < .001). CONCLUSIONS: The number of defined patient-specific and surgical risk factors, especially those with greater than two, were associated with increased index surgical costs and diminished cost-utility. Efforts to optimize patient physiology and minimize surgical risk would likely reduce healthcare expenditures and improve the overall cost-utility profile for ASD interventions.Level of evidence: III.

Trends in usage of navigation and robotic assistance in elective spine surgeries: a study of 105,212 cases from 2007 to 2015.

OBJECTIVE: Identify trends of navigation and robotic-assisted elective spine surgeries. METHODS: Elective spine surgery patients between 2007 and 2015 in the Nationwide Inpatient Sample (NIS) were isolated by ICD-9 codes for Navigation [Nav] or Robotic [Rob]-Assisted surgery. Basic demographics and surgical variables were identified via chi-squared and t tests. Each system was analyzed from 2007 to 2015 for trends in usage. RESULTS: Included 3,759,751 patients: 100,488 Nav; 4724 Rob. Nav were younger (56.7 vs 62.7 years), had lower comorbidity index (1.8 vs 6.2, all p < 0.05), more decompressions (79.5 vs 42.6%) and more fusions (60.3 vs 52.6%) than Rob. From 2007 to 2015, incidence of complication increased for Nav (from 5.8 to 21.7%) and Rob (from 3.3 to 18.4%) as well as 2-3 level fusions (from 50.4 to 52.5%) and (from 1.3 to 3.2%); respectively. Invasiveness increased for both (Rob: from 1.7 to 2.2; Nav: from 3.7 to 4.6). Posterior approaches (from 27.4 to 41.3%), osteotomies (from 4 to 7%), and fusions (from 40.9 to 54.2%) increased in Rob. Anterior approach for Rob decreased from 14.9 to 14.4%. Nav increased posterior (from 51.5% to 63.9%) and anterior approaches (from 16.4 to 19.2%) with an increase in osteotomies (from 2.1 to 2.7%) and decreased decompressions (from 73.6 to 63.2%). CONCLUSIONS: From 2007 to 2015, robotic and navigation systems have been performed on increasingly invasive spine procedures. Robotic systems have shifted from anterior to posterior approaches, whereas navigation computer-assisted procedures have decreased in rates of usage for decompression procedures.

Concurrent Presence of Thoracolumbar Scoliosis and Chiari Malformation: Is Operative Risk Magnified?

STUDY DESIGN: Retrospective review of Kids' Inpatient Database (KID). PURPOSE: Identify the risks and complications associated with surgery in adolescents diagnosed with Chiari and scoliosis. OVERVIEW OF LITERATURE: Scoliosis is frequently associated with Chiari malformation (CM). More specifically, reports have been made about this association with CM type I in the absence of syrinx status. METHODS: The KID was used to identify all pediatric inpatients with CM and scoliosis. The patients were stratified into three groups: those with concomitant CM and scoliosis (CMS group), those with only CM (CM group), and those with only scoliosis (Sc group). Multivariate logistic regressions were used to assess association between surgical characteristics and diagnosis with complication rate. RESULTS: A total of 90,707 spine patients were identified (61.8% Sc, 37% CM, 1.2% CMS). Sc patients were older, had a higher invasiveness score, and higher Charlson comorbidity index (all p<0.001). CMS patients had significantly higher rates of surgical decompression (36.7%). Sc patients had significantly higher rates of fusions (35.3%) and osteotomies (1.2%, all p<0.001). Controlling for age and invasiveness, postoperative complications were significantly associated with spine fusion surgery for Sc patients (odds ratio [OR], 1.8; p<0.05). Specifically, posterior spinal fusion in the thoracolumbar region had a greater risk of complications (OR, 4.9) than an anterior approach (OR, 3.6; all p<0.001). CM patients had a significant risk of complications when an osteotomy was performed as part of their surgery (OR, 2.9) and if a spinal fusion was concurrently performed (OR, 1.8; all p<0.05). Patients in the CMS cohort were significantly likely to develop postoperative complications if they underwent a spinal fusion from both anterior (OR, 2.5) and posterior approach (OR, 2.7; all p<0.001). CONCLUSIONS: Having concurrent scoliosis and CM increases operative risk for fusion surgeries despite approach. Being independently inflicted with scoliosis or Chiari leads to increased complication rate when paired with thoracolumbar fusion and osteotomies; respectively.

Failure to Normalize Risk Profile of Spine Fusion Patients With Coronary Artery Disease Previously Treated With Percutaneous Stent Revascularization.

BACKGROUND: The impact of an initially less invasive cardiac intervention on outcomes of future surgical spine procedures has been understudied; therefore, we sought to investigate the effect of coronary stents on postoperative outcomes in an elective spine fusion cohort. METHODS: Elective spine fusion patients were isolated with International Classification of Diseases-Ninth Edition and current procedural terminology procedure codes in the PearlDiver database. Patients were stratified by number of coronary stents: (1) 1 to 2 stents (ST12); (2) 3 to 4 stents (ST34); (3) no stents. Mean comparison tests compared differences in demographics, diagnoses, comorbidities, and 30-day and 90-day complication outcomes. Logistic regression assessed the odds of complications associated with coronary stents, controlling for levels fused, age, sex, and comorbidities (odds ratio [95% confidence interval]). Statistical significance was P < 0.05. RESULTS: A total of 726,061 elective spine fusion patients were isolated. Of those patients, 707,396 patients had no stent, 17,087 ST12, and 1578 ST34. At baseline (BL), ST12 patients had higher rates of morbid obesity, chronic kidney disease, congestive heart failure, chronic obstructive pulmonary disease, and diabetes mellitus compared with no stent and ST34 patients (all P < 0.001). Relative to no stent patients, ST12 patients had a longer length of stay and, at 30 days, significantly higher complication rates, including pneumonia, myocardial infarction (MI), sepsis, acute kidney injury, urinary tract infection (UTI), wound complications, transfusions, and 30-day readmissions (P < 0.05). Controlling for age, sex, comorbidities, and levels fused, ST12 was a significant predictor of MI within 30 days (OR 2.15 [95% CI 1.7-2.7], P < 0.001) and 90 days postoperatively (OR 1.87 [95% CI 1.6-2.2], P < 0.001). ST34 patients compared with no stent patients at 30 days presented with increased rates of complication, including pneumonia, MI, sepsis, UTI, wound complications, and 30-day readmissions. Regression analysis showed no significant differences in complications between ST12 vs ST34 at 30 days, but at 90 days, ST34 was associated with significantly increased rate and odds of death (1.1% vs 0.3%, P = 0.021; OR 1.94 [95% CI 1.13-3.13], P = 0.01). CONCLUSION: Cardiac stents failed to normalize risk profile of patients with coronary artery disease. Postoperatively at 90 days, elective spine fusion patients with 3 or more stents were significantly at risk of mortality compared with patients with fewer or no stents.

Predictors of Complication Severity Following Adult Spinal Deformity Surgery: Smoking Rate, Diabetes, and Osteotomy Increase Risk of Severe Adverse Events.

BACKGROUND: Given the physical and economic burden of complications in spine surgery, reducing the prevalence of perioperative adverse events is a primary concern of both patients and health care professionals. This study aims to identify specific perioperative factors predictive of developing varying grades of postoperative complications in adult spinal deformity (ASD) patients, as assessed by the Clavien-Dindo complication classification (Cc) system. METHODS: Surgical ASD patients ≥18 years were identified in the American College of Surgeons' National Surgical Quality Improvement Program from 2005 to 2015. Postoperative complications were stratified by Cc grade severity: minor (I, II, and III) and severe (IV and V). Stepwise regression models generated dataset-specific predictive models for Cc groups. Model internal validation was achieved by bootstrapping and calculating the area under the curve (AUC) of the model. Significance was set at P < 0.05. RESULTS: Included were 3936 patients (59 ± 16 years, 63% women, 29 ± 7 kg/m2) undergoing surgery for ASD (4.4 ± 4.7 levels, 71% posterior approach, 11% anterior, and 18% combined). Overall, 1% of cases were revisions, 39% of procedures involved decompression, 27% osteotomy, and 15% iliac fixation. Additionally, 66% of patients experienced at least 1 complication, 0% of which were Cc grade I, 51% II, 5% III, 43% IV, and 1% V. The final model predicting severe Cc (IV-V) complications yielded an AUC of 75.6% and included male sex, diabetes, increased operative time, central nervous system tumor, osteotomy, cigarette pack-years, anterior decompression, and anterior lumbar interbody fusion. Final models predicting specific Cc grades were created. CONCLUSIONS: Specific predictors of adverse events following ASD-corrective surgery varied for complications of different severities. Multivariate modeling showed smoking rate, osteotomy, diabetes, anterior lumbar interbody fusion, and higher operative time, among other factors, as predictive of severe complications, as classified by the Clavien-Dindo Cc system. These factors can help in the identification of high-risk patients and, consequently, improve preoperative patient counseling. CLINICAL RELEVANCE: The findings of this study provide a foundation for identifying ASD patients at high risk of postoperative complications .

External Validation of the National Surgical Quality Improvement Program Calculator Utilizing a Single Institutional Experience for Adult Spinal Deformity Corrective Surgery.

BACKGROUND: Identify the external applicability of the American College of Surgeons' National Surgical Quality Improvement Program (NSQIP) risk calculator in the setting of adult spinal deformity (ASD) and subsets of patients based on deformity and frailty status. METHODS: ASD patients were isolated in our single-center database and analyzed for the shared predictive variables displayed in the NSQIP calculator. Patients were stratified by frailty (not frail <0.03, frail 0.3-0.5, severely frail >0.5), deformity [T1 pelvic angle (TPA) > 30, pelvic incidence minus lumbar lordosis (PI-LL) > 20], and reoperation status. Brier scores were calculated for each variable to validate the calculator's predictability in a single center's database (Quality). External validity of the calculator in our ASD patients was assessed via Hosmer-Lemeshow test, which identified whether the differences between observed and expected proportions are significant. RESULTS: A total of 1606 ASD patients were isolated from the Quality database (48.7 years, 63.8% women, 25.8 kg/m2); 33.4% received decompressions, and 100% received a fusion. For each subset of ASD patients, the calculator predicted lower outcome rates than what was identified in the Quality database. The calculator showed poor predictability for frail, deformed, and reoperation patients for the category "any complication" because they had Brier scores closer to 1. External validity of the calculator in each stratified patient group identified that the calculator was not valid, displaying P values >0.05. CONCLUSION: The NSQIP calculator was not a valid calculator in our single institutional database. It is unable to comment on surgical complications such as return to operating room, surgical site infection, urinary tract infection, and cardiac complications that are typically associated with poor patient outcomes. Physicians should not base their surgical plan solely on the NSQIP calculator but should consider multiple preoperative risk assessment tools.

The Effects of Global Alignment and Proportionality Scores on Postoperative Outcomes After Adult Spinal Deformity Correction.

BACKGROUND: Recent studies have suggested achieving global alignment and proportionality (GAP) alignment may influence mechanical complications after adult spinal deformity (ASD) surgery. OBJECTIVE: To investigate the association between the GAP score and mechanical complications after ASD surgery. METHODS: Patients with ASD with at least 5-level fusion to pelvis and minimum 2-year data were included. Multivariate analysis was used to find an association between proportioned (P), GAP-moderately disproportioned, and severely disproportioned (GAP-SD) states and mechanical complications (inclusive of proximal junctional kyphosis [PJK], proximal junctional failure [PJF], and implant-related complications [IC]). Severe sagittal deformity was defined by a "++" in the Scoliosis Research Society (SRS)-Schwab criteria for sagittal vertebral axis or pelvic incidence and lumbar lordosis. RESULTS: Two hundred ninety patients with ASD were included. Controlling for age, Charlson comorbidity index, invasiveness and baseline deformity, and multivariate analysis showed no association of GAP-moderately disproportioned patients with proximal junctional kyphosis, PJF, or IC, while GAP-SD patients showed association with IC (odds ratio [OR]: 1.7, [1.1-3.3]; P = .043). Aligning in GAP-relative pelvic version led to lower likelihood of all 3 mechanical complications (all P < .04). In patients with severe sagittal deformity, GAP-SD was predictive of IC (OR: 2.1, [1.1-4.7]; P = .047), and in patients 70 years and older, GAP-SD was also predictive of PJF development (OR: 2.5, [1.1-14.9]; P = .045), while improving in GAP led to lower likelihood of PJF (OR: 0.2, [0.02-0.8]; P = .023). CONCLUSION: Severely disproportioned in GAP is associated with development of any IC and junctional failure specifically in older patients and those with severe baseline deformity. Therefore, incorporation of patient-specific factors into realignment goals may better strengthen the utility of this novel tool.

Improvements in Outcomes and Cost After Adult Spinal Deformity Corrective Surgery Between 2008 and 2019.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To assess whether patient outcomes and cost-effectiveness of adult spinal deformity (ASD) surgery have improved over the past decade. BACKGROUND: Surgery for ASD is an effective intervention, but one that is also associated with large initial healthcare expenditures. Changes in the cost profile for ASD surgery over the last decade has not been evaluated previously. MATERIALS AND METHODS: ASD patients who received surgery between 2008 and 2019 were included. Analysis of covariance was used to establish estimated marginal means for outcome measures [complication rates, reoperations, health-related quality of life, total cost, utility gained, quality adjusted life years (QALYs), cost-efficiency (cost per QALY)] by year of initial surgery. Cost was calculated using the PearlDiver database and represented national averages of Medicare reimbursement for services within a 30-day window including length of stay and death differentiated by complication/comorbidity, revision, and surgical approach. Internal cost data was based on individual patient diagnosis-related group codes, limiting revisions to those within two years (2Y) of the initial surgery. Cost per QALY over the course of 2008-2019 were then calculated. RESULTS: There were 1236 patients included. There was an overall decrease in rates of any complication (0.78 vs . 0.61), any reoperation (0.25 vs . 0.10), and minor complication (0.54 vs . 0.37) between 2009 and 2018 (all P <0.05). National average 2Y cost decreased at an annual rate of $3194 ( R2 =0.6602), 2Y utility gained increased at an annual rate of 0.0041 ( R2 =0.57), 2Y QALYs gained increased annually by 0.008 ( R2 =0.57), and 2Y cost per QALY decreased per year by $39,953 ( R2 =0.6778). CONCLUSION: Between 2008 and 2019, rates of complications have decreased concurrently with improvements in patient reported outcomes, resulting in improved cost effectiveness according to national Medicare average and individual patient cost data. The value of ASD surgery has improved substantially over the course of the last decade.

Cervical deformity patients with baseline hyperlordosis or hyperkyphosis differ in surgical treatment and radiographic outcomes.

Background: Patients with symptomatic cervical deformity (CD) requiring surgical correction often present with hyperkyphosis (HK), although patients with hyperlordotic curves may require surgery as well. Few studies have investigated differences in CD corrective surgery with regard to HK and hyperlordosis (HL). Objective: The objective of the study is to evaluate patterns in treatment for CD patients with baseline (BL) HK and HL and understand how extreme curvature of the spine may influence surgical outcomes. Materials and Methods: Operative CD patients with BL and 1-year (1Y) radiographic data were included in the study. Patients were stratified based on BL C2-C7 lordosis (CL) angle: those >1 standard deviation (SD) from the mean (-6.96 ± 21.47°) were hyperlordotic (>14.51°) or hyperkyphotic (<-28.43°) depending on directionality. Patients within 1SD were considered control group. Results: 102 surgical CD patients (61 years, 65% F, 30 kg/m2) with BL and 1Y radiographic data were included. 20 patients met definitions for HK and 21 patients met definitions for HL. No differences in demographics or disability were noted. HK had higher estimated blood loss (EBL) with anterior approaches than HL but similar EBL with posterior approach. Operative time did not differ between groups. Control, HL, and HK groups differed in BL TS-CL (36.6° vs. 22.5° vs. 60.7°, P < 0.001) and BL-SVA (10.8 vs. 7.0 vs. -47.8 mm, P = 0.001). HL patients had less discectomies, less corpectomies, and similar osteotomy rates to HK. HL had 3x revisions of HK and controls (28.6 vs. 10.0 vs. 9.2%, respectively, P = 0.046). At 1Y, HL patients had higher cSVA and trended higher SVA and SS than HK. In terms of BL-upper cervical alignment, HK patients had higher McGregor's slope (MGS) (16.1° vs. 3.3°, P = 0.002) and C0-C2 Cobb (43.3° vs. 26.9°, P < 0.001), however, postoperative differences in MGS and C0-C2 were not significant. HK drivers of deformity were primarily C (90%), whereas HL had primary CT (38.1%), UT (23.8%), and C (14.3%) drivers. Conclusions: Hyperlodotic patients trended higher revision rates with greater radiographic malalignment at 1-year postoperative, perhaps due to undercorrection compared to kyphotic etiologies.

Highest Achievable Outcomes for Patients Undergoing Cervical Deformity Corrective Surgery by Frailty.

BACKGROUND: Frailty is influential in determining operative outcomes, including complications, in patients with cervical deformity (CD). OBJECTIVE: To assess whether frailty status limits the highest achievable outcomes of patients with CD. METHODS: Adult patients with CD with 2-year (2Y) data included. Frailty stratification: not frail (NF) <0.2, frail (F) 0.2 to 0.4, and severely frail (SF) >0.4. Analysis of covariance established estimated marginal means based on age, invasiveness, and baseline deformity, for improvement, deterioration, or maintenance in Neck Disability Index (NDI), Modified Japanese Orthopaedic Association (mJOA), and Numerical Rating Scale Neck Pain. RESULTS: One hundred twenty-six patients with CD included 29 NF, 83 F, and 14 SF. The NF group had the highest rates of deterioration and lowest rates of improvement in cervical Sagittal Vertical Axis and horizontal gaze modifiers. Two-year improvements in NDI by frailty: NF: -11.2, F: -16.9, and SF: -14.6 ( P = .524). The top quartile of NF patients also had the lowest 1-year (1Y) NDI (7.0) compared with F (11.0) and SF (40.5). Between 1Y and 2Y, 7.9% of patients deteriorated in NDI, 71.1% maintained, and 21.1% improved. Between 1Y and 2Y, SF had the highest rate of improvement (42%), while NF had the highest rate of deterioration (18.5%). CONCLUSION: Although frail patients improved more often by 1Y, SF patients achieve most of their clinical improvement between 1 and 2Y. Frailty is associated with factors such as osteoporosis, poor alignment, neurological status, sarcopenia, and other medical comorbidities. Similarly, clinical outcomes can be affected by many factors (fusion status, number of pain generators within treated levels, integrity of soft tissues and bone, and deformity correction). Although accounting for such factors will ultimately determine whether frailty alone is an independent risk factor, these preliminary findings may suggest that frailty status affects the clinical outcomes and improvement after CD surgery.

Trends in Outcomes of a Prospective Consecutively Enrolled Single-Center Adult Cervical Deformity Series.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: The aim was to describe the two-year outcomes for patients undergoing surgical correction of cervical deformity (CD). BACKGROUND: Adult CD has been shown to compromise health-related quality of life. While advances in spinal realignment have shown promising short-term clinical results in this parameter, the long-term outcomes of CD corrective surgery remain unclear. MATERIALS AND METHODS: Operative CD patients >18 years with two-year (2Y) health-related quality of life/radiographic data were included. Improvement in radiographic, neurologic, and health-related quality of life outcomes were reported. Patients with a prior cervical fusion and patients with the greatest and smallest change based on Neck Disability Index (NDI), numeric rating scale (NRS) neck, modified Japanese Orthopaedic Association (mJOA) were compared using multivariable analysis controlling for age, and frailty, and invasiveness. RESULTS: One hundred and fifty-eight patients were included in this study. By 2Y, 96.3% of patients improved in Ames cervical sagittal vertical axis modifier, 34.2% in T1 slope minus cervical lordosis (TS-CL), 42.0% in horizontal gaze modifier, and 40.9% in SVA modifier. In addition, 65.5% of patients improved in Passias CL modifier, 53.3% in TS-CL modifier, 100% in C2-T3 modifier, 88.9% in C2S modifier, and 81.0% in MGS modifier severity by 2Y. The cohort significantly improved from baseline to 2Y in NDI, NRS Neck, and mJOA, all P <0.05. 59.3% of patients met minimal clinically important difference for NDI, 62.3% for NRS Neck, and 37.3% for mJOA. Ninety-seven patients presented with at least one neurologic deficit at baseline and 63.9% no longer reported that deficit at follow-up. There were 45 (34.6%) cases of distal junctional kyphosis (DJK) (∆DJKA>10° between lower instrumented vertebra and lower instrumented vertebra-2), of which 17 were distal junctional failure (distal junctional failure-DJK requiring reoperation). Patients with the greatest beneficial change were less likely to have had a complication in the two-year follow-up period. CONCLUSION: Correction of CD results in notable clinical and radiographic improvement with most patients achieving favorable outcomes after two years. However, complications including DJK or failure remain prevalent.

The Additional Economic Burden of Frailty in Adult Cervical Deformity Patients Undergoing Surgical Intervention.

SUMMARY OF BACKGROUND DATA: The influence of frailty on economic burden following corrective surgery for the adult cervical deformity (CD) is understudied and may provide valuable insights for preoperative planning. OBJECTIVE: To assess the influence of baseline frailty status on the economic burden of CD surgery. STUDY DESIGN: Retrospective cohort. MATERIALS AND METHODS: CD patients with frailty scores and baseline and two-year Neck Disability Index data were included. Frailty score was categorized patients by modified CD frailty index into not frail (NF) and frail (F). Analysis of covariance was used to estimate marginal means adjusting for age, sex, surgical approach, and baseline sacral slope, T1 slope minus cervical lordosis, C2-C7 angle, C2-C7 sagittal vertical axis. Costs were derived from PearlDiver registry data. Reimbursement consisted of a standardized estimate using regression analysis of Medicare payscales for services within a 30-day window including length of stay and death. This data is representative of the national average Medicare cost differentiated by complication/comorbidity outcome, surgical approach, and revision status. Cost per quality-adjusted life-year (QALY) at two years was calculated for NF and F patients. RESULTS: There were 126 patients included. There were 68 NF patients and 58 classified as F. Frailty groups did not differ by overall complications, instance of distal junctional kyphosis, or reoperations (all P >0.05). These groups had similar rates of radiographic and clinical improvement by two years. NF and F had similar overall cost ($36,731.03 vs. $37,356.75, P =0.793), resulting in equivocal costs per QALYs for both patients at two years ($90,113.79 vs. $80,866.66, P =0.097). CONCLUSION: F and NF patients experienced similar complication rates and upfront costs, with equivocal utility gained, leading to comparative cost-effectiveness with NF patients based on cost per QALYs at two years. Surgical correction for CD is an economical healthcare investment for F patients when accounting for anticipated utility gained and cost-effectiveness following the procedure. LEVEL OF EVIDENCE: III.

CD4+ T-Cell Epitope Prediction by Combined Analysis of Antigen Conformational Flexibility and Peptide-MHCII Binding Affinity.

Antigen processing in the class II MHC pathway depends on conventional proteolytic enzymes, potentially acting on antigens in native-like conformational states. CD4+ epitope dominance arises from a competition among antigen folding, proteolysis, and MHCII binding. Protease-sensitive sites, linear antibody epitopes, and CD4+ T-cell epitopes were mapped in plague vaccine candidate F1-V to evaluate the various contributions to CD4+ epitope dominance. Using X-ray crystal structures, antigen processing likelihood (APL) predicts CD4+ epitopes with significant accuracy for F1-V without considering peptide-MHCII binding affinity. We also show that APL achieves excellent performance over two benchmark antigen sets. The profiles of conformational flexibility derived from the X-ray crystal structures of the F1-V proteins, Caf1 and LcrV, were similar to the biochemical profiles of linear antibody epitope reactivity and protease sensitivity, suggesting that the role of structure in proteolysis was captured by the analysis of the crystal structures. The patterns of CD4+ T-cell epitope dominance in C57BL/6, CBA, and BALB/c mice were compared to epitope predictions based on APL, MHCII binding, or both. For a sample of 13 diverse antigens, the accuracy of epitope prediction by the combination of APL and I-Ab-MHCII-peptide affinity reached 36%. When MHCII allele specificity was also diverse, such as in human immunity, prediction of dominant epitopes by APL alone reached 42% when using a stringent scoring threshold. Because dominant CD4+ epitopes tend to occur in conformationally stable antigen domains, crystal structures typically are available for analysis by APL, and thus, the requirement for a crystal structure is not a severe limitation.

Predicting 30-Day Perioperative Outcomes in Adult Spinal Deformity Patients With Baseline Paralysis or Functional Dependence.

BACKGROUND: Patients undergoing surgical treatment of adult spinal deformity (ASD) are often preoperatively risk stratified using standardized instruments to assess for perioperative complications. Many ASD instruments account for medical comorbidity and radiographic parameters, but few consider a patient's ability to independently accomplish necessary activities of daily living (ADLs). METHODS: Patients ≥18 years undergoing ASD corrective surgery were identified in National Surgical Quality Improvement Program. Patients were grouped by (1) plegic status and (2) dependence in completing ADLs ("totally dependent" = requires total assistance in ADLs, "partially dependent" = uses prosthetics/devices but still requires help, "independent" = requires no help). Quadriplegics and totally dependent patients comprised "severe functional dependence," paraplegics/hemiplegics who are "partially dependent" comprised "moderate functional dependence," and "independent" nonplegics comprised "independent." Analysis of variance with post hoc testing and Kruskal-Wallis tests compared demographics and perioperative outcomes across groups. Logistic regression found predictors of inferior outcomes, controlling for age, sex, body mass index (BMI), and invasiveness. Subanalysis correlated functional dependence with other established metrics such as the modified Frailty Index (mFI) and Charlson Comorbidity Index (CCI). RESULTS: A total of 40,990 ASD patients (mean age 57.1 years, 53% women, mean BMI 29.8 kg/m2) were included. Mean invasiveness score was 6.9 ± 4.0; 95.2% were independent (Indep), 4.3% moderate (Mod), and 0.5% severe (Sev). Sev had higher baseline invasiveness than Mod or Indep groups (9.0, 8.3, and 6.8, respectively, P < 0.001). Compared with the Indep patients, Sev and Mod had significantly longer inpatient length of stay (LOS; 10.9, 8.4, 3.8 days, P < 0.001), higher rates of surgical site infection (2.2%, 2.9%, 1.5%, P < 0.001), and more never events (17.7%, 9.9%, 4.0%, P < 0.001). Mod had higher readmission rates than either the Sev or Indep groups (30.2%, 2.7%, 10.3%, P < 0.001). No differences in implant failure were observed (P > 0.05). Controlling for age, sex, BMI, CCI, invasiveness, and frailty, regression equations showed increasing functional dependence significantly increased odds of never events (OR, 1.82 [95% CI 1.57-2.10], P < 0.001), specifically urinary tract infection (OR, 2.03 [95% CI 1.66-2.50], P < 0.001) and deep venous thrombosis (OR, 2.04 [95% CI 1.61-2.57], P < 0.001). Increasing functional dependence also predicted longer LOS (OR, 3.16 [95% CI 2.85-3.46], P < 0.001) and readmission (OR, 2.73 [95% CI 2.47-3.02], P < 0.001). Subanalysis showed functional dependence correlated more strongly with mFI (r = 0.270, P < 0.001) than modified CCI (mCCI; r = 0.108, P < 0.001), while mFI and mCCI correlated most with one another (r = 0.346, P < 0.001). CONCLUSIONS: Severe functional dependence had significantly longer LOS and more never-event complications than moderate or independent groups. Overall, functional dependence may show superiority to traditional metrics in predicting poor perioperative outcomes, such as increased LOS, readmission rate, and risk of surgical site infection and never events.

Cervical Deformity Correction Fails to Achieve Age-Adjusted Spinopelvic Alignment Targets.

OBJECTIVE: To assess whether surgical cervical deformity (CD) patients meet spinopelvic age-adjusted alignment targets, reciprocal, and lower limb compensation changes. STUDY DESIGN: Retrospective review. METHODS: CD was defined as C2-C7 lordosis >10°, cervical sagittal vertical angle (cSVA) >4 cm, or T1 slope minus cervical lordosis (TS-CL) >20°. Inclusion criteria were age >18 years and undergoing surgical correction with complete baseline and postoperative imaging. Published formulas were used to create age-adjusted alignment target for pelvic tilt (PT), pelvic incidence and lumbar lordosis (PI-LL), sagittal vertical angle (SVA), and lumbar lordosis and thoracic kyphosis (LL-TK). Actual alignment was compared with age-adjusted ideal values. Patients who matched ±10-year thresholds for age-adjusted targets were compared with unmatched cases (under- or overcorrected). RESULTS: A total of 120 CD patients were included (mean age, 55.1 years; 48.4% women; body mass index, 28.8 kg/m2). For PT, only 24.4% of patients matched age-adjusted alignment, 51.1% overcorrected for PT, and 24.4% undercorrected. For PI-LL, only 27.6% of CD patients matched age-adjusted targets, with 49.4% overcorrected and 23% undercorrected postoperatively. Forty percent of patients matched age-adjusted target for SVA, 41.3% overcorrected, and 18.8% undercorrected. CD patients who had worsened in TS-CL or cSVA postoperatively displayed increased TK (-41.1° to -45.3°, P = 1.06). With lower extremity compensation, CD patients decreased in ankle flexion angle postoperatively (6.1°-5.5°, P = 0.036) and trended toward smaller sacrofemoral angle (199.6-195.6 mm, P = 0.286) and knee flexion (2.6° to -1.1°, P = 0.269). CONCLUSIONS: In response to worsening CD postoperatively, patients increased in TK and recruited less lower limb compensation. Almost 75% of CD patients did not meet previously established spinopelvic alignment goals, of whom a subset of patients were actually made worse off in these parameters following surgery. This finding raises the question of whether we should be looking at the entire spine when treating CD.

The Inherent Value of Preoperative Optimization-Absolute and Incremental Reduction in Components of Metabolic Syndrome Can Enhance Recovery and Minimize Perioperative Burden.

BACKGROUND: Metabolic syndrome (MetS) is an amalgamation of medical disorders that ultimately increase patient complications. Factors such as obesity, hypertension, dyslipidemia, and diabetes are associated with this disease complex. OBJECTIVE: To assess the incremental value of improving MetS in relation to clinical outcomes. STUDY DESIGN: Retrospective cohort study. METHODS: Patients undergoing elective spine surgery were isolated and separated into 2 groups: MetS patients (>2 metabolic variables: hypertension, diabetes, obesity, and triglycerides) and nonmetabolic patients (<2 metabolic variables). T tests and χ 2 tests compared differences in patient demographics. Resolution of metabolic factors was incrementally analyzed for their effect on perioperative complications through utilization of logistic regressions. RESULTS: A total of 2,855,517 elective spine patients were included. Of them, 20.1% had MeTS (81.4% two factors, 18.4% three factors, 0.2% four factors). MetS patients were older, less female, and more comorbid (P < 0.001). About 28.8% MetS patients developed more complications such as anemia (9.8% vs 5.9%), device related (3.5% vs 2.9%), neurologic (2.3% vs 1.4%), and bowel issues (9.7% vs 6.8 %; P < 0.05). Controlling for age and procedure invasiveness, having 3 MetS factors increased a patient's likelihood (0.89×) of developing a perioperative complication (P < 0.05), whereas 2 factors had lower odds (0.82). More specifically, patients who were diabetes, obese, and had hypertension had the greatest odds at developing a complication (0.58 [0.58-0.57]) followed by those who had concomitant hypertension, high triglycerides, and were obese (0.55 [0.63-0.48]; all P < 0.001). MetS patients with 2 factors, being obese and having hypertension produced the lowest odds at developing a complication (0.5 [0.61-0.43]; P < 0.001). These MetS patients also had a lower length of stay than those with 3 and 4 (P < 0.001). CONCLUSIONS: Metabolic patients improved in perioperative complications incrementally, demonstrating the utility of efforts to mitigate burden of MetS even if not completely abolished. CLINICAL RELEVANCE: This review contributes to the assessment of MetS optimization in the field of adult spine surgery.

"Reverse roussouly": cervicothoracic curvature ratios define characteristic shapes in adult cervical deformity.

PURPOSE: To investigate normal curvature ratios of the cervicothoracic spine and to establish radiographic thresholds for severe myelopathy and disability, within the context of shape. METHODS: Adult cervical deformity (CD) patients undergoing cervical fusion were included. C2-C7 Cobb angle (CL) and thoracic kyphosis (TK), using T2-T12 Cobb angle, were used as a ratio, ranging from -1 to + 1. Pearson bivariate r and univariate analyses analyzed radiographic correlations and differences in myelopathy(mJOA > 14) or disability(NDI > 40) across ratio groups. RESULTS: Sixty-three CD patients included. Regarding CL:TK ratio, 37 patients had a negative ratio and 26 patients had a positive ratio. A more positive CL:TK correlated with increased TS-CL(r = 0.655, p = < 0.001)and mJOA(r = 0.530, p = 0.001), but did not correlate with cSVA/SVA or NDI scores. A positive CL:TK ratio was associated with moderate disability(NDI > 40)(OR: 7.97[1.22-52.1], p = 0.030). Regression controlling for CL:TK ratio revealed cSVA > 25 mm increased the odds of moderate to severe myelopathy and cSVA > 30 mm increased the odds of significant neck disability. Lastly, TS-CL > 29 degrees increased the odds of neck disability by 4.1 × with no cutoffs for severe mJOA(p > 0.05). CONCLUSIONS: Cervical deformity patients with an increased CL:TK ratio had higher rates of moderate neck disability at baseline, while patients with a negative ratio had higher rates of moderate myelopathy clinically. Specific thresholds for cSVA and TS-CL predicted severe myelopathy or neck disability scores, regardless of baseline neck shape. A thorough evaluation of the cervical spine should include exploration of relationships with the thoracic spine and may better allow spine surgeons to characterize shapes and curves in cervical deformity patients.