Corrective Surgery For Adult Spinal Deformity Research Articles

Adult spinal deformity correction surgery using age-adjusted alignment thresholds: clinical outcomes and mechanical complication rates. A systematic review of the literature.

Adult spinal deformity (ASD) surgery gives good clinical outcomes but has a high rate of mechanical complications (MC). In 2016, Lafage described the age-adjusted alignment thresholds (AAAT) to adapt the correction in relation to patient's age proposing less aggressive corrections for the elderly population. The aim of this review was to clarify the effectiveness of AAAT to achieve good health-related quality of life (HRQoL) and their relationship with post-operative MC. We performed a review of the literature, including articles reporting data on post-operative HRQoL and MC rates in relation to the AAAT. Data were stratified according to whether they matched the AAAT, dividing the population in undercorrected (U), matched (M) and overcorrected (O). The quality of the included studies was assessed using the GRADE and MINORS systems. Six articles reporting data from 1,825 patients were included. The different categories (U, M and O) had homogeneous pre-operative sagittal parameters (p > 0.05) that became statistically different after surgeries (p < 0.05). Proximal junctional kyphosis (PJK) was more frequent in the O group compared to U (p = 0.05). Post-operative HRQoL parameters were similar in the 3 groups (p > 0.05). The quality of the included studies was generally low with a high bias risk. The results extrapolated from this review are interesting, as for the same HRQoL the U group had a lower MC rate. Unfortunately, the results are inconsistent, mainly because of the low quality of the included studies and the lack of reporting of some important patient- and surgery-related factors.

5. Sustenance of substantial clinical benefit in adult spinal deformity corrective surgery patients: a minimum 5-year outcomes analysis

5. Sustenance of substantial clinical benefit in adult spinal deformity corrective surgery patients: a minimum 5-year outcomes analysis

137. Achievement and maintenance of optimal alignment following adult spinal deformity corrective surgery: a 5-year outcome analysis

137. Achievement and maintenance of optimal alignment following adult spinal deformity corrective surgery: a 5-year outcome analysis

External Validation of the Global Alignment and Proportion Score as Prognostic Tool for Corrective Surgery in Adult Spinal Deformity: A Systematic Review and Meta-Analysis

Since its proposal, the Global Alignment and Proportion (GAP) score has been the topic of several external validation studies, which have yielded conflicting results. Given the lack of consensus regarding this prognostic tool, the authors aim to assess the accuracy of GAP scores for predicting mechanical complications following adult spinal deformity correction surgery. A systematic search was performed using PubMed, Embase, and Cochrane Library for the purpose of identifying all studies evaluating the GAP score as a predictive tool for mechanical complications. GAP scores were pooled using a random-effects model to compare patients reporting mechanical complications after surgery versus those reporting no complications. Where receiver operator curves were provided, the area under the curve (AUC) was pooled. A total of 15 studies featuring 2092 patients were selected for inclusion. Qualitative analysis using Newcastle-Ottawa criteria revealed moderate quality among all included studies (5.99/9). With respect to sex, the cohort was predominantly female (82%). The pooled mean age among all patients in the cohort was 58.55years, with a mean follow-up of 33.86months after surgery. Upon pooled analysis, we found that mechanical complications were associated with higher mean GAP scores, albeit minimal (mean difference=0.571 [ 95% confidence interval: 0.163-0.979]; P= 0.006, n= 864). Additionally, age (P= 0.136, n= 202), fusion levels (P= 0.207, n= 358), and body mass index (P= 0.616, n= 350) were unassociated with mechanical complications. Pooled AUC revealed poor discrimination overall (AUC=0.69; n= 1206). GAP scores may have a minimal-to-moderate predictive capability for mechanical complications associated with adult spinal deformity correction.

Treatment of adult deformity surgery by orthopedic and neurological surgeons: trends in treatment, techniques, and costs by specialty

BACKGROUND CONTEXTSurgery to correct adult spinal deformity (ASD) is performed by both neurological surgeons and orthopedic surgeons. Despite well-documented high costs and complication rates following ASD surgery, there is a dearth of research investigating trends in treatment according to surgeon subspeciality. PURPOSEThe purpose of this investigation was to perform an analysis of surgical trends, costs and complications of ASD operations by physician specialty using a large, nationwide sample. STUDY DESIGN/SETTINGRetrospective cohort study using an administrative claims database. PATIENT SAMPLEA total of 12,929 patients were identified with ASD that underwent deformity surgery performed by neurological or orthopedic surgeons. OUTCOME MEASURESThe primary outcome was surgical case volume by surgeon specialty. Secondary outcomes included costs, medical complications, surgical complications, and reoperation rates (30-day, 1-year, 5-year, and total). METHODSThe PearlDiver Mariner database was queried to identify patients who underwent ASD correction from 2010 to 2019. The cohort was stratified to identify patients who were treated by either orthopedic or neurological surgeons. Surgical volume, baseline characteristics, and surgical techniques were examined between cohorts. Multivariable logistic regression was employed to assess the cost, rate of reoperation and complication according to each subspecialty while controlling for number of levels fused, rate of pelvic fixation, age, gender, region and Charlson Comorbidity Index (CCI). Alpha was set to 0.05 and a Bonferroni correction for multiple comparisons was utilized to set the significance threshold at p ≤.000521. RESULTSA total of 12,929 ASD patients underwent deformity surgery performed by neurological or orthopedic surgeons. Orthopedic surgeons performed most deformity procedures accounting for 64.57% (8,866/12,929) of all ASD operations, while the proportion treated by neurological surgeons increased 44.2% over the decade (2010: 24.39% vs 2019: 35.16%; p<.0005). Neurological surgeons more frequently operated on older patients (60.52 vs 55.18 years, p<.0005) with more medical comorbidities (CCI scores: 2.01 vs 1.47, p<.0005). Neurological surgeons also performed higher rates of arthrodesis between one and six levels (OR: 1.86, p<.0005), three column osteotomies (OR: 1.35, p<.0005) and navigated or robotic procedures (OR: 3.30, p<.0005). Procedures performed by orthopedic surgeons had significantly lower average costs as compared to neurological surgeons (orthopedic surgeons: $17,971.66 vs neurological surgeons: $22,322.64, p=.253). Adjusted logistic regression controlling for number of levels fused, pelvic fixation, age, sex, region, and comorbidities revealed that patients within neurosurgical care had similar odds of complications to orthopaedic surgery. CONCLUSIONSThis investigation of over 12,000 ASD patients demonstrates orthopedic surgeons continue to perform the majority of ASD correction surgery, although neurological surgeons are performing an increasingly larger percentage over time with a 44% increase in the proportion of surgeries performed in the decade. In this cohort, neurological surgeons more frequently operated on older and more comorbid patients, utilizing shorter-segment fixation with greater use of navigation and robotic assistance.

Impact of Frailty on the Development of Proximal Junctional Failure: Does Frailty Supersede Achieving Optimal Realignment?

Patients undergoing surgery for adult spinal deformity (ASD) are often elderly, frail, and at elevated risk of adverse events perioperatively, with proximal junctional failure (PJF) occurring relatively frequently. Currently, the specific role of frailty in potentiating this outcome is poorly defined. To determine if the benefits of optimal realignment in ASD, with respect to the development of PJF, can be offset by increasing frailty. Retrospective cohort. Operative ASD patients (scoliosis >20°, SVA>5cm, pelvic tilt>25°, or TK>60°) fused to the pelvis or below with available baseline and 2-year (2Y) radiographic and HRQL data were included. The Miller Frailty Index (FI) was used to stratify patients into 2 categories: Not Frail (FI <3) and Frail (>3). Proximal Junctional Failure (PJF) was defined using the Lafage criteria. "Matched" and "unmatched" refers to ideal age-adjusted alignment postoperatively. Multivariable regression determined the impact of frailty on the development of PJF. Two hundred eighty-four ASD patients met inclusion criteria [62.2yrs±9.9, 81%F, BMI: 27.5kg/m 2 ±5.3, ASD-FI: 3.4±1.5, Charlson Comorbidity Index (CCI): 1.7±1.6]. Forty-three percent of patients were characterized as Not Frail (NF) and 57% were characterized as Frail (F). PJF development was lower in the NF group compared with the F group (7% vs . 18%; P =0.002). F patients had 3.2 × higher risk of PJF development compared to NF patients (OR: 3.2, 95% CI: 1.3-7.3, P =0.009). Controlling for baseline factors, F unmatched patients had a higher degree of PJF (OR: 1.4, 95% CI:1.02-1.8, P =0.03); however, with prophylaxis, there was no increased risk. Adjusted analysis shows F patients, when matched postoperatively in PI-LL, had no significantly higher risk of PJF. An increasingly frail state is significantly associated with the development of PJF after corrective surgery for ASD. Optimal realignment may mitigate the impact of frailty on eventual PJF. Prophylaxis should be considered in frail patients who do not reach ideal alignment goals.

123 Early Postural Stability Changes in Patients Undergoing Correction of Spinal Deformity

INTRODUCTION: Adult spinal deformity (ASD) is an increasingly prevalent cause of pain and disability. It is known that ASD correction results in improved alignment, but not whether this alignment results in objective improvements in postural stability. METHODS: A retrospective review of a prospectively maintained database identified 16 patients undergoing ASD correction surgery with five or more segments. Balance was assessed via a force plate pre- and three months postoperatively. Participants were instructed to stand still, with their hands at their sides and eyes open. Center of pressure (COP) and center of gravity (COG) parameters were analyzed and used to derive head sway in the Dubousset cone of economy (COE). Spinopelvic parameters (PI, PT, SVA, and LL) on standing scoliosis radiographic films were also measured pre- and three months postoperatively. RESULTS: In our 16-patient series, there was a mean age of 61.3 years-old, and a median of 10 segments fused. Postoperative force plate assessment showed a decrease in total COP sway and sway velocity (p &lt; 0.05). Coronal COP sway and sway velocity also decreased (p &lt; 0.05). There was a decrease in total, coronal and sagittal COG sway and sway velocity postoperatively (p &lt; 0.05). In the COE, total head sway decreased (p &lt; 0.05). PT remained unchanged following surgical correction, while LL and SVA improved from 44.9° to 56.7° (p &lt; 0.01) and 82.2 to 22.5 mm (p &lt; 0.01), respectively. PI-LL mismatch also improved from 16.2° to 4.8° (p &lt; 0.01). CONCLUSIONS: Following long segment fusion for ASD, postural stability may improve as early as three months, concomitant with improved spinopelvic alignment. We believe force plate assessment warrants further study for postoperative evaluation of postural alignment and clinical outcomes in ASD patients.

Does Adult Spinal Deformity Affect Cardiac Function? A Prospective Perioperative Study.

Prospective comparative study. The objective of this study was to investigate perioperative cardiac function using echocardiography in patients undergoing surgery for the adult spinal deformity (ASD). Corrective surgery for ASD has increased, especially in older persons. However, perioperative complication rates remain high in ASD surgery, including cardiopulmonary complications. This study included patients with ASD who underwent surgery between May 2016 and April 2018. A cardiologist performed all echocardiography imaging preoperatively and 2 weeks postoperatively. Left ventricular contractility was measured using left ventricular ejection fraction (LVEF), and right ventricular contractility was measured using tricuspid annular plane systolic excursion (TAPSE) and tricuspid annular peak systolic velocity (S'). Spinopelvic radiographic parameters, the apices of thoracic kyphosis and lumbar lordosis, and the inflection point where the vertebral curvature changes from kyphosis to lordosis were also measured. Differences between preoperative and postoperative measurements for continuous variables were analyzed using a paired Student t test. Differences in continuous and categorical variables between two independent groups were analyzed using an unpaired Student t test and Fisher exact test, respectively. Multivariate logistic regression analyses were performed to detect influential factors. Sixty-one patients were included [12 males and 49 females; average age, 64.0 (22-84)yr]. LVEF, TAPSE, and S', respectively changed from 64.4%, 24.9mm, and 14.3cm/s to 65.4%, 25mm, and 15cm/s postoperatively with no significance. However, in LVEF<59.3% (average-1SD), TAPSE<17mm, and S'<11.8cm/s cases, respectively, these increased significantly from 55.7%, 17.9mm, and 10.5cm/s to 60.9%, 21.4mm, and 14.2cm/s postoperatively ( P =0.036, 0.029, and 0.022, respectively). The LVEF<59.3% group showed a significantly lower inflection point level (1.5 vs. 2.9) preoperatively ( P =0.007). The S'<11.8cm/s group showed significantly larger thoracic kyphosis (28.3° vs. 19.4°) preoperatively ( P =0.013). Perioperative cardiac function did not deteriorate after surgery in patients with ASD. In those with lower cardiac function preoperatively, there were significant improvements noted postoperatively. The preoperative inflection point level was significantly lower in the lower LVEF group. Preoperative thoracic kyphosis was significantly larger in the lower tricuspid annular peak systolic velocity group.

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

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. 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. 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. 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.

Three Cases of Additional Correction with Kickstand Rod Technique for Persisted Coronal Malalignment during Thoracic Spine to Iliac Fusion in Adult Spinal Deformity Correction Surgery

Three Cases of Additional Correction with Kickstand Rod Technique for Persisted Coronal Malalignment during Thoracic Spine to Iliac Fusion in Adult Spinal Deformity Correction Surgery

Postoperative Gravity Line-Hip Axis Offset as a Substantial Risk Factor for Mechanical Failure After Adult Spinal Deformity Correction Surgery.

Mechanical failure (MF) is a serious burden for patients with adult spinal deformity (ASD) who have undergone deformity correction surgery. Surgeons have sought to understand the mechanism and prevent this problematic complication, but this goal remains to be achieved. The gravity line (GL) of the whole body is a noteworthy parameter that represents global sagittal balance, for which normative values for the axial skeleton have been studied. To assess postoperative GL-hip axis (GL-HA) offset as a critical risk factor for MF after ASD correction surgery. Consecutive patients who underwent initial surgery for ASD at a single academic center were retrospectively included. Demographics, operative details, preoperative and postoperative spinopelvic parameters, global sagittal balance parameters, and Scoliosis Research Society-22 score were evaluated. These variables were analyzed for differences and correlations with MF. Thirty-five patients without MF and 30 patients with MF were identified in the study. Two groups showed no significant differences in baseline demographics, operative characteristics, preoperative global sagittal balance parameters, or preoperative and postoperative Scoliosis Research Society-22 scores. Significant differences and correlations with MF were observed for postoperative GL-HA offset using a cutoff value of 49.3 mm from logistic regression analysis, with an odds ratio of 11.0 (95% confidence interval: 3.45-35.01, P < .0001). Postoperative GL-HA offset is a substantial risk factor for MF after ASD surgery. Surgical correction of ASD with a GL-HA offset greater than 5 cm is significantly related to MF. The GL should be located near the HA after ASD surgery.

Changes in health-related quality of life measures associated with degree of proximal junctional kyphosis.

To explore the changes in health-related quality of life parameters observed in patients experiencing varying degrees of proximal junctional kyphosis following corrective adult spinal deformity fusions. Inclusion: adult spinal deformity patients > 18 y/o, undergoing spinal fusion. PJK: ≥ 10° measure of the sagittal Cobb angle between the inferior endplate of the UIV and the superior endplate of the UIV + 2. Severe PJK: > 28° PJK. Mild PJK: ≥ 10oand ≤ 28°. ANOVA, followed by ANCOVA, compared the change in HRQoLs between time points (BL, 1Y, 2Y) among PJK groups. Correlation-related change in PJK and change in HRQoL for mild and severe groups. 969 patients (age: 64.5 y/o,75% F, posterior levels fused:12.3) were studied. 59% no PJK, 32% mild PJK, 9% severe PJK. No differences in HRQoLs were seen between no PJK and PJK groups at baseline, one year, and 2 years. Adjusted analysis revealed Severe PJK patients improved less in SRS-22 Satisfaction (NoPJK: 1.6, MildPJK: 1.6, SeverePJK: 1.0; p = 0.022) scores at 2years. Linear regression analysis only found clinical improvement in SRS-22 Satisfaction to correlate with the change of the PJK angle by 2years (R = 0.176, P = 0.008). No other HRQoL metric correlated with either the incidence of PJK or the change in the PJK angle by one or 2years. These results maintain that patients presenting with and without proximal junctional kyphosis report similar health-related qualities of life following corrective adult spinal deformity surgery, and SRS-22 Satisfaction may be a clinical correlate to the degree of PJK. Rather than proving proximal junctional kyphosis to have a minimal clinical impact overall on HRQoL metrics, these data suggest that future analysis of this phenomenon requires different assessments. Level of evidence: III.

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

A retrospective cohort study. To assess whether patient outcomes and cost-effectiveness of adult spinal deformity (ASD) surgery have improved over the past decade. 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. 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. 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). 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.

Pelvic Nonresponse Following Treatment of Adult Spinal Deformity: Influence of Realignment Strategies on Occurrence.

Despite adequate correction, the pelvis may fail to readjust, deemed pelvic nonresponse (PNR). To assess alignment outcomes [PNR, proximal junctional kyphosis (PJK), postoperative cervical deformity (CD)] following adult spinal deformity (ASD) surgery utilizing different realignment strategies. ASD patients with two-year data were included. PNR defined as undercorrected in age-adjusted pelvic tilt (PT) at six weeks and maintained at two years. Patients classified by alignment utilities: (a) improvement in Scoliosis Research Society-Schwab sagittal vertical axis, (b) matching in age-adjusted pelvic incidence-lumbar lordosis, (c) matching in Roussouly, (d) aligning Global Alignment and Proportionality (GAP) score. Multivariable regression analyses, controlling for age, baseline deformity, and surgical factors, assessed rates of PNR, PJK, and CD development following realignment. A total of 686 patients met the inclusion criteria. Rates of postoperative PJK and CD were not significant in the PNR group (both P >0.15). PNR patients less often met substantial clinical benefit in Oswestry Disability Index by two years [odds ratio: 0.6 (0.4-0.98)]. Patients overcorrected in age-adjusted pelvic incidence-lumbar lordosis, matching Roussouly, or proportioned in GAP at six weeks had lower rates of PNR (all P <0.001). Incremental addition of classifications led to 0% occurrence of PNR, PJK, and CD. Stratifying by baseline PT severity, Low and moderate deformity demonstrated the least incidence of PNR (7.7%) when proportioning in GAP at six weeks, while severe PT benefited most from matching in Roussouly (all P <0.05). Following ASD corrective surgery, 24.9% of patients showed residual pelvic malalignment. This occurrence was often accompanied by undercorrection of lumbopelvic mismatch and less improvement of pain. However, overcorrection in any strategy incurred higher rates of PJK. We recommend surgeons identify a middle ground using one, or more, of the available classifications to inform correction goals in this regard. III.

P95. A comparative analysis of thoracic decompensation versus proximal junctional kyphosis in response to adult spinal deformity corrective surgery

<h3>BACKGROUND CONTEXT</h3> Thoracic decompensation (TD) represents a distinct radiographic complexity from proximal junctional kyphosis (PJK). Few studies exist on the occurrence of TD following adult spinal deformity (ASD) corrective surgery. <h3>PURPOSE</h3> To assess the incidence of TD following ASD-corrective surgery in comparison with the occurrence of PJK. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> ASD, TD, PJK, thoracic compensation. <h3>METHODS</h3> ASD patients with complete baseline (BL) and two-year (2Y) followup were included. Patients were divided into groups: those who developed TD: T4-T12 >54.2° and those who developed PJK. Further analysis assessed outcomes among patients with both TD and PJK (TDPJK). Thoracic compensation was defined as expected thoracic kyphosis minus BL thoracic kyphosis. Means comparison tests and multivariable logistic regression analysis assessed differences between patient groups. <h3>RESULTS</h3> A total of 373 patients met inclusion criteria. Patient breakdown by radiographic outcome was: TD (N=31), PJK (N=223) and TDPJK (N=119). Age, gender, and ASD-mFI were similar between TD and PJK patients. TD patients were more likely to be osteoporotic than PJK patients, p < 0.05. Procedures on TD patients were less invasive and utilized a shorter construct (9.3 vs 11.5 levels; both p < 0.05). TD patients had significantly greater cervical lordosis, thoracic kyphosis, and lumbar lordosis than PJK patients at BL and 2Y follow-up, all p < 0.05. Thoracic compensation was significantly associated with TD (OR 1.07 [CI 1.04-1.09], p < 0.001) controlling for age, ASD-mFI, and invasiveness. TDPJK had the highest complication rate (84.9%), significantly greater than PJK patients (70.9%), and TD patients (61.3%), both p < 0.05. PJK patients were 78.7% less likely to develop PJF than TDPJK patients (OR 0.213 [CI 0.101-0.453], p < 0.001). <h3>CONCLUSIONS</h3> Patients who developed thoracic decompensation were more likely to present with osteoporosis, but had less invasive procedures and levels fused than patients with proximal junctional kyphosis. The tradeoff between fusing too much resulting in proximal junctional kyphosis and fusing too little predisposing to thoracic decompensation can serve as the basis of future studies to determine optimal construct length to balance these two risks. Thoracic compensation was predictive of postoperative thoracic decompensation in adult spinal deformity-correction. Patients who developed TDPJK had the highest rate of complications and greater odds of junctional failure. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

163. Assessing the influence of modifiable patient-related factors on complication rates following adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Surgical correction of adult spinal deformity (ASD) has been associated with superior alignment and functional outcomes. However, postoperative complication rates remain relatively high. The extent to which potentially modifiable patient-related factors can influence complication rates in adult spinal deformity patients has not been effectively evaluated. <h3>PURPOSE</h3> Evaluate the association between modifiable patient-related factors on complications following ASD corrective surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective. <h3>PATIENT SAMPLE</h3> A total of 689 ASD patients. <h3>OUTCOME MEASURES</h3> Complication and reoperation rates. <h3>METHODS</h3> ASD patients with 2-year (2Y) data were included. Complication groups were defined as follows: 1) any complication; 2) major; 3) medical (cardiac event, ileus, etc.); surgical (site infection, wound dehiscence, etc.); 5) major mechanical (implant failure, rod fracture); 6) major radiographic (PJF [proximal junctional failure], pseudarthrosis, adjacent segment disease); and 7) reoperation. Modifiable risk factors included current smoker, obesity (BMI >30kg/m²), osteoporosis, alcohol use, depression (BL SF-36 MCS <35, perMatcham), psychiatric diagnosis and hypertension. Patients were stratified by BL deformity severity in T1PA (LowDef/HighDef) and age above or below 65 (Young/Older). Means comparison tests assessed prevalence of modifiable risk factors present in those developing specified complications. Binary logistic regression analysis was used to adjust for confounders. <h3>RESULTS</h3> A total of 480 ASD patients met inclusion criteria (age 59±15 yrs, 77%F, BMI 27±5 kg/m², CCI: 1.7±1.7). By 2Y, comp rates: 72% one complication, 28% major, 21% medical, 27% surgical, 11% major radiographic, and 8% had a major mechanical complication. A total of 106 patients (22%) required reoperation. Overall, 318 patients (66%) had at least one of the preoperative risk factors. Age-Deformity Groups: 32% Young LowDef, 19% Young HighDef, 18% Older LowDef, 31% Older HighDef. Within Young LowDef, patients with osteoporosis were more likely to suffer either a major mechanical or radiographic comp (both OR >6, p<.05), although this trend was not seen in the overall cohort. Young HighDef patients were much more likely to develop complications if obese, especially major mechanical complications (OR: 2.8, [1.04-8.6]; p=.045), while patients with depression or a psychiatric diagnosis suffered major radiographic comps and underwent reoperation more often. Older patients with HighDef developed significantly more complications when diagnosed with depression, including major radiographic comps (23% vs 8%, OR: 3.5, [1.1-10.6]; p=.03). Overall, when controlling for baseline deformity, frailty, and osteoporosis, a diagnosis of depression proved to be a significant risk factor for development of major radiographic complications (OR: 2.4, [1.3-4.5]; p=.005). <h3>CONCLUSIONS</h3> Certain modifiable patient-related factors, especially mental health status, are associated with increased risk for complications following spinal deformity surgery. Therefore, with consideration to clinical presentation, elaborate on the utility in medical intervention prior to undergoing spinal deformity corrective surgery. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P85. Detailed risk factor stratification in adult spinal deformity corrective surgery: a 3-year cost utility analysis

BACKGROUND CONTEXT A previous study by Pellisé et al identified strong preoperative and surgical predictors of major complications. It is unknown which of these risk factors has the most significant impact on cost-effectiveness. PURPOSE To assess the impact of previously established risk factors on the cost effectiveness of ASD surgery. STUDY DESIGN/SETTING Retrospective. PATIENT SAMPLE A total of 689 ASD patients. OUTCOME MEASURES Quality adjusted life years (QALYs), utility gained, ODI, total cost. METHODS ASD patients with baseline (BL) and 2-year postoperative (2Y) data were included. Frailty score, sagittal deformity measures (SVA, PI-LL, T1 Sagittal Tilt), blood loss and surgical time were divided into tertiles, with the highest tertile being classified as high risk. Since some patients have multiple risk factors, they may be included in multiple groups. Descriptive analysis identified demographics, radiographic parameters and surgical factors. Published methods for cost was calculated using the PearlDiver database and CMS.gov definitions. Cost per QALY at 2Y was calculated for each risk factor. RESULTS There were 422 patients included. Of the 381 patients with a risk factor, 77% were fused to the pelvis, 44% were highly frail, 56% had a high deformity, 34% had high EBL and 34% had high operative time. When analyzing BL scores, highly frail patients had the highest mean ODI and EQ-5D. After undergoing surgery, patients with a high EBL had the highest rate of SICU admissions, rate of any complications and rate of major complications. This translated to patients with high EBL having the lowest utility gained at 2Y. Interestingly, patients with high frailty had the highest rates of implant complications and pseudarthrosis resulting in the second highest major complication rates and total estimated cost. Despite this high estimated cost, however, patients with high frailty also achieved the highest utility gained at 2Y resulting in the best cost-utility at two years. CONCLUSIONS Despite having higher rates of implant failures, pseudarthrosis, and major complications, highly frail patients managed to generate the highest utility gained and best cost-effectiveness, while higher blood loss had higher rates of complications as well, but demonstrated the lowest utility gained and cost-utility. Therefore, spine surgeons should limit intraoperative risk factors, such as blood loss and operative time, which would minimize postoperative complications and improve overall cost-effectiveness during correction of adult spinal deformity. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. A previous study by Pellisé et al identified strong preoperative and surgical predictors of major complications. It is unknown which of these risk factors has the most significant impact on cost-effectiveness. To assess the impact of previously established risk factors on the cost effectiveness of ASD surgery. Retrospective. A total of 689 ASD patients. Quality adjusted life years (QALYs), utility gained, ODI, total cost. ASD patients with baseline (BL) and 2-year postoperative (2Y) data were included. Frailty score, sagittal deformity measures (SVA, PI-LL, T1 Sagittal Tilt), blood loss and surgical time were divided into tertiles, with the highest tertile being classified as high risk. Since some patients have multiple risk factors, they may be included in multiple groups. Descriptive analysis identified demographics, radiographic parameters and surgical factors. Published methods for cost was calculated using the PearlDiver database and CMS.gov definitions. Cost per QALY at 2Y was calculated for each risk factor. There were 422 patients included. Of the 381 patients with a risk factor, 77% were fused to the pelvis, 44% were highly frail, 56% had a high deformity, 34% had high EBL and 34% had high operative time. When analyzing BL scores, highly frail patients had the highest mean ODI and EQ-5D. After undergoing surgery, patients with a high EBL had the highest rate of SICU admissions, rate of any complications and rate of major complications. This translated to patients with high EBL having the lowest utility gained at 2Y. Interestingly, patients with high frailty had the highest rates of implant complications and pseudarthrosis resulting in the second highest major complication rates and total estimated cost. Despite this high estimated cost, however, patients with high frailty also achieved the highest utility gained at 2Y resulting in the best cost-utility at two years. Despite having higher rates of implant failures, pseudarthrosis, and major complications, highly frail patients managed to generate the highest utility gained and best cost-effectiveness, while higher blood loss had higher rates of complications as well, but demonstrated the lowest utility gained and cost-utility. Therefore, spine surgeons should limit intraoperative risk factors, such as blood loss and operative time, which would minimize postoperative complications and improve overall cost-effectiveness during correction of adult spinal deformity.

141. Comparative analysis of utilization of artificial intelligence in minimally invasive adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Advancements in artificial intelligence (AI), machine learning, and minimally-invasive (MIS) technique may offer enhanced preoperative planning, intraoperative robotic or navigational guidance, and prediction of postoperative complications for adult spinal deformity patients. Despite relatively widespread utilization, few studies in the literature assess the clinical and radiographic impact of AI in MIS surgery. <h3>PURPOSE</h3> To assess the impact of artificial intelligence on peri- and postoperative course in minimally-invasive adult spinal deformity corrective surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort review. <h3>PATIENT SAMPLE</h3> This study included 524 MIS patients. <h3>OUTCOME MEASURES</h3> Intra- and postoperative complication rates; reoperation rate; HRQLs <h3>METHODS</h3> Operative cervical deformity patients 18 years old with complete pre-(BL) and up to 2-year (2Y) postop radiographic/HRQL data were stratified by primary utilization AI-based patient-specific rod customization and robotic or navigational assistance in pre- and perioperative course (AI+) or not (AI-). Differences in demographics, clinical outcomes, radiographic alignment targets, perioperative factors and complication rates were assessed via means comparison analysis. Analysis of covariance (ANCOVA) assessed postoperative complications while controlling for BL age and gender. <h3>RESULTS</h3> A total of 133 MIS patients were included (51.74±11.59 years, 41% female, 30.85±6.93 kg/m²). Of these patients, 44 (33.1%) were classified as AI+. At baseline, patient groups were comparable in BL age, BMI and CCI (all p>.05), though AI+ patients were more likely to be male (p=.040). Patient groups were comparable in terms of both regional and global radiographic alignment, as well as HRQLs at BL (all p>.05). Surgically, AI+ patients had significantly shorter operative times overall (p=.022) and decreased EBL (p=.001), as well as decreased likelihood of undergoing corpectomy (p=.001). Furthermore, AI+ patients reported significantly lower hospital LOS vs AI- patients (p=.012). At 2 years postoperatively, AI+ patients with custom rods were noted to have significantly improved segmental alignment in terms of decreased pelvic tilt (S1PT) and pelvic incidence (S1PI) (both p <.001). Adjusted complications analysis revealed that AI+ patients were significantly less likely to experience any postoperative complication (p=.003), neurological complications (p=.021) or complication requiring reoperation (p=.003). <h3>CONCLUSIONS</h3> Artificial intelligence and machine learning technologies may provide a substantial benefit to patients undergoing minimally-invasive adult spinal deformity surgery. The findings in this study demonstrate that patients operated on using AI-based robotic or navigational guidance, as well as the utilization of customized instrumentation, may reduce intraoperative invasiveness, shorten hospital length of stay, and decrease complication rates. As such, surgeons should consider utilization of AI-based technology in practice. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

115. Discriminative ability of commonly used contemporary risk indices to predict adverse outcomes following adult spinal deformity corrective surgery

<h3>BACKGROUND CONTEXT</h3> It is imperative to determine which factors have greater implications on postoperative outcomes, which can afford tailored treatment plans for adult spinal deformity (ASD) patients. <h3>PURPOSE</h3> To determine the discriminative ability of commonly used indices to predict adverse outcomes after corrective surgery for adult spinal deformity. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> This study included 9,763 patients. <h3>OUTCOME MEASURES</h3> Perioperative complications. <h3>METHODS</h3> ASD patients from the National Surgical Quality Improvement Program (NSQIP) 2005-2015 were included. Logistic regression analysis determined significant odds ratios among complications between the following indices and demographics: Passias et al modified frailty index score for ASD (mFI-ASD), the modified Charlson Comorbidity Index (mCCI), ASA classification score, age and body mass index (BMI). Using multivariate analysis, indices and demographics that demonstrated significance for predicting complications were identified. CIT run forest analysis generated an index threshold value for all complications tested. <h3>RESULTS</h3> Included: 9,763 ASD patients. At least 4 of the 5 risk indices were significant for the following complications: any type, major, cardiac, infection and death. None of the indices correlated with reoperation or readmission. The mFI-ASD demonstrated the highest odds ratio (OR) for all complications (p <.001), followed by ASA status. Modified CCI also correlated with a higher OR for all five complications, compared to age and BMI. An index threshold value for each complication was determined by CIT run forest analysis. Analysis of threshold values showed mFI had the highest ORs for any complication (OR: 3.50) as well as infection (OR: 2.53). ASA status, on the other hand, had the highest ORs for major complications (OR: 2.93), cardiac complications (OR: 4.09) and death (OR: 10.18). <h3>CONCLUSIONS</h3> The modified FI-ASD demonstrated superiority in predicting adverse postoperative outcomes, compared to various commonly used indices and patient characteristics. These findings are important as it allows spine surgeons to appropriately counsel their patients preoperatively. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

53. Determination of risk benefit thresholds for corrective adult spinal deformity surgery with consideration of frailty and severity of sagittal malalignment at presentation

<h3>BACKGROUND CONTEXT</h3> Adult spinal deformity is associated with severe pain and disability. Recent literature has shown that surgical intervention can significantly improve patient's quality of life and lessen disease burden. As many patients requiring spine surgery are elderly and often frail, restoration of alignment targets may differ. There is paucity in literature on whether different frailty and deformity states may warrant a different level of surgical invasiveness. <h3>PURPOSE</h3> To investigate the effect of frailty and deformity severity on appropriate surgical invasiveness. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study from multicenter database. <h3>PATIENT SAMPLE</h3> This study included 381 adult spinal deformity (ASD) patients. <h3>OUTCOME MEASURES</h3> Complications; health-related quality of life (HRQL); Oswestry Disability Index (ODI). <h3>METHODS</h3> Operative ASD patients (scoliosis >20, SVA>5cm, PT>25, or TK>60) with available baseline (BL) and 2-year (2Y) radiographic and HRQL data were included. The ASD-FI was used to stratify patients into 2 categories: Not Frail (NF): 20. Four groups were formed by frailty and deformity severity: NF Low, F Low, NF Sev, F Sev. ANCOVA determined differences in Surgical Invasiveness (SI) among F/D groups. Logistic regression determined significant association between SI and reaching Ideal Clinical outcome (ICO), defined as: no major complications, no reoperations, and reaching MCID for ODI. Surgical Invasiveness (SI) was normalized to a scale of 0-100 using the SI range. Thresholds for invasiveness and achieving ICO were found through conditional inference tree (CIT) analysis. <h3>RESULTS</h3> A total of 381 ASD patients (59.3±15yrs, 26.9± kg/m2, CCI: 1.52±1.6, FI: 3.09±1.6) were included and underwent surgery (11.6±4 lvls fused, EBL: 1522±1275 mL, op time: 337±124 min, LOS: 7.3±3.9 days), with 62.2% having a posterior-only approach, 36.5% combined approach, 46% having a decompression and 65% an osteotomy. By deformity severity: 60% Low-Mod, 40% Severe, while frailty assessment was 49% NF, and 51% F. This categorized the patients into deformity/frailty groups as follows: 35% NF Low, 13% NF Sev, 22% F Low, 25% F Sev. Patients had a significantly different degree of SI: 35 NF Low/Mod, 38 F Low/mod, 48 NF Sev, 50 F Sev (p<0.001). CIT analysis found NF Sev patients had a higher likelihood of reaching ICO with an SI below 40 (OR: 3.6, 95% CI: 1.1-12.1, p=.037), and F Sev with a SI below 30 (OR: 4.6, 95% CI: 1.7-12.6, p=.003). Low/mod groups revealed no significant association between invasiveness and achieving ICO. <h3>CONCLUSIONS</h3> Analysis of increasing surgical invasiveness in patients stratified by frailty and baseline deformity showed frail severely deformed patients, compared with non-frail severely deformed patients, had a lower invasiveness threshold above which there was a higher risk of major complications, reoperations and failure to reach clinically important improvement in ODI. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.