Faculty Bibliography

AIMS/OBJECTIVE:Postoperative complication rates remain relatively high after adult spinal deformity (ASD) surgery. The extent to which modifiable patient-related factors influence complication rates in patients with ASD has not been effectively evaluated. The aim of this retrospective cohort study was to evaluate the association between modifiable patient-related factors and complications after corrective surgery for ASD. METHODS:ASD patients with two-year data were included. Complications were categorized as follows: any complication, major, medical, surgical, major mechanical, major radiological, and reoperation. Modifiable risk factors included smoking, obesity, osteoporosis, alcohol use, depression, psychiatric diagnosis, and hypertension. Patients were stratified by the degree of baseline deformity (low degree of deformity (LowDef)/high degree of deformity (HighDef): below or above 20°) and age (Older/Younger: above or below 65 years). Complication rates were compared for modifiable risk factors in each age/deformity group, using multivariable logistic regression analysis to adjust for confounders. RESULTS:A total of 480 ASD patients met the inclusion criteria. By two years, complication rates were 72% ≥ one complication, 28% major, 21% medical, 27% surgical, 11% major radiological, 8% major mechanical, and 22% required reoperation. Younger LowDef patients with osteoporosis were more likely to suffer either a major mechanical (odds ratio (OR) 5.9 (95% confidence interval (CI) 1.1 to 36.9); p = 0.048) or radiological complication (OR 7.0 (95% CI 1.9 to 25.9); p = 0.003). Younger HighDef patients were much more likely to develop complications if obese, especially major mechanical complications (OR 2.8 (95% CI 1.1 to 8.6); p = 0.044). Older HighDef patients developed more complications when diagnosed with depression, including major radiological complications (OR 3.5 (95% CI 1.1 to 10.6); p = 0.033). Overall, a diagnosis of depression proved to be a risk factor for the development of major radiological complications (OR 2.4 (95% CI 1.3 to 4.5); p = 0.005). CONCLUSION/CONCLUSIONS: 2022;104-B(11):1249-1255.

STUDY DESIGN/METHODS:Retrospective single-center, consecutively enrolled database of adult spinal deformity (ASD) patients. OBJECTIVE:To assess the performance of the mASD-FI in predicting clinical and patient-reported outcomes after ASD-corrective surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:The recently described modified Adult Spinal Deformity frailty index (mASD-FI) quantifies frailty of ASD patients, but the utility of this clinical prediction tool as a means of prognosticating postoperative outcomes has not been investigated. METHODS:ASD patients with available mASD-FI scores and HRQL data at presentation and 2-years postop were included. Patients were stratified by mASD-FI score using published cutoffs: not frail (NF,<7), frail (F,7-12), severely frail (SF,>12). ANOVA assessed differences in patient factors across frailty groups. Linear regression assessed the relationship of mASD-FI with length of stay(LOS) and HRQLs. Multivariable logistic regression revealed how frailty category predicted odds of complications, infections and reoperation. RESULTS:509 pts included (59yrs, 79%F, 27.7 kg/m2). The cohort presented with moderate baseline deformity: SVA (83.7mm±71), PT (12.7°±10.8), PI-LL (43.1°±21.1). Mean preoperative mASD-FI score was 7.2, frailty category: NF (50.3%), F (34.0%), SF (15.7%). Age, BMI, and CCI increased with frailty categories (all p < 0.001); however, fusion length (p = 0.247) and osteotomy rate (p = 0.731) did not. At baseline, increasing frailty was associated with inferior ODI, EQ-5D, SRS-22r, PCS, and NRS Back and Leg (all p < 0.001). Greater frailty was associated with increased LOS and reduced postoperative HRQL. Controlling for complication incidence, baseline mASD-FI predicted 2 year postop scores for year ODI (b = 0.7, 0.58-0.8, p < 0.001) SRS (b = -0.023, -0.03 - -0.02, p < 0.001), EQ-5D (b = -0.003, -0.004 - -0.002, p < 0.001). F and SF were associated with greater odds of unplanned revision surgery and complications. CONCLUSION/CONCLUSIONS:Higher preoperative mASD-FI score was associated with significantly greater complications, higher rate of unplanned reoperations and lower postoperative HRQL in this investigation. The mASD-FI provides similar prognostic utility while reducing burden for surgeons and patients.

SUMMARY OF BACKGROUND DATA/BACKGROUND:The influence of frailty on economic burden following corrective surgery for adult cervical deformity (CD) is understudied and may provide valuable insights for pre-operative planning. OBJECTIVE:To assess the influence of baseline frailty status on the economic burden of CD surgery. STUDY DESIGN/METHODS:Retrospective cohort. METHODS:CD patients with frailty scores and baseline (BL) and 2-year (2Y) NDI data were included. Frailty score was categorized patients by mFI-CD into Not Frail (NF) and Frail (F). ANCOVA was used to estimate marginal means adjusting for age, sex, surgical approach, and baseline Sacral Slope, TS-CL, C2-C7 angle, cSVA. Costs were derived from PearlDiver registry data. Reimbursement consisted of a standardized estimate using regression analysis of Medicare pay-scales for services within a 30-day window including length of stay and death. This data is representative of national average Medicare cost differentiated by complication/comorbidity outcome, surgical approach, and revision status. Cost per Quality-Adjusted Life Year (QALY) at 2Y was calculated for NF and F patients. RESULTS:There were 126 patients included. There were 68 Not Frail patients and 58 classified as Frail (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 2Y ($90,113.79 vs. $80,866.66, P=0.097). CONCLUSION/CONCLUSIONS:Frail and not frail patients experienced similar complication rates and upfront costs, with equivocal utility gained, leading to a comparative cost effectiveness with non-frail patients based on cost per QALYs at two years. Surgical correction for cervical deformity is an economical healthcare investment for frail patients, when accounting for anticipated utility gained and cost-effectiveness following the procedure. LEVEL OF EVIDENCE/METHODS:III.

STUDY DESIGN/SETTING/METHODS:Retrospective cohort. OBJECTIVE:Adult spinal deformity (ASD) corrective surgery is often a highly invasive procedure portending patients to both immediate and long-term complications. Therefore, we sought to compare the economic impact of certain complications before and after 2 years. METHODS:2 years postoperatively. Published methods converted ODI to SF-6D to QALYs. Cost was calculated using CMS.gov definitions. Marginalized means for utility gained and cost-per-QALY were calculated via ANCOVA controlling for significant confounders. RESULTS:2 years. CONCLUSION/CONCLUSIONS:Mechanical complications had the single greatest impact on cost-utility after adult spinal deformity surgery, but less so after 2 years. Understanding the cost-utility of specific interventions at certain timepoints may mitigate economic burden and prophylactic efforts should strategically be made against early mechanical complications.

BACKGROUND CONTEXT: Despite studies reporting the efficacy of BMP to promote surgical spinal fusion, hospital systems and third-party payors continue to deny use of BMP, claiming high cost and lack of long term follow up. PURPOSE: Perform a propensity score matched analysis of complications and cost-effectiveness for surgically treated adult spinal deformity (ASD) patients receiving BMP vs no BMP. STUDY DESIGN/SETTING: Prospective, multicenter, propensity score matched analysis. PATIENT SAMPLE: ASD patients enrolled into a prospective multicenter study. OUTCOME MEASURES: Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Short Form-36v2 questionnaire (SF-36), Oswestry Disability Index (ODI), cost of care, cost/QALY, postoperative complications.
METHOD(S): Surgically treated ASD patients prospectively enrolled into a multicenter study from 2009-2018 were assessed for receiving BMP or NOBMP (iliac crest bone graft and allograft only) at the time of surgery. BMP and NOBMP cohorts were propensity score matched (PSM) for age, BMI, frailty, total levels fused, fusion to the pelvis, osteotomies, interbody fusion and supplemental rod use. Postoperative alignment, complications, rod fractures, patient-reported outcomes (PROMs), cost of care (based on DRG reimbursements adjusted to 2021 US dollars), were evaluated at minimum 3-year follow-up, and cost/QALY calculated at 1-,2-, and minimum 3-year follow-up.
RESULT(S): Of 888 patients, 483 (mean 4.2 years follow-up, range 2.9 to 8.8) were evaluated. Mean BMP dosage was 27.6 mg total (range 1 to 200), 2.2 mg/level posterior (range 0 to 25) and 1.7 mg/level interbody (range 0 to 18). BMP (n=407) had similar demographics, osteotomies, total and interbody levels fused, preop PROMs, follow-up duration, and pre- and postoperative spinal alignment as NOBMP (n=76; p>0.05). BMP had fewer implant failures (0.17/patient vs 0.33/patient; p 0.05). At last follow-up, BMP had better SF-36 social function (46.7 vs 43.9) and SF-36 mental component scores (51.5. vs 47.8) than NOBMP (p <0.05, respectively). BMP had lower mean total cost of care/patient ($78,679.61 vs $103,388.78) and lower cost/QALY ($22,455.48 vs $32,947.68) at last follow-up vs NOBMP, respectively (p < 0.05). Revision surgery rates were similar for BMP vs NOBMP (0.32 vs 0.42/patient, p=0.11); however, costs of revision surgery were less for BMP ($11,114.33) vs NOBMP ($22,912.53, p <0.05).
CONCLUSION(S): Propensity score matched analysis demonstrated BMP use in ASD surgery at mean 4-year follow-up was associated with decreased implant fracture rates, lower treatment costs and better cost/QALY than NOBMP. Hospital systems, administrators and third-party payors should consider that the initial cost of BMP use at index surgery may be offset by decreased total cost of care and improve cost/QALY for ASD patients. FDA DEVICE/DRUG STATUS: Bone morphogenetic protein: Investigational.
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BACKGROUND CONTEXT: Malalignment following adult spinal deformity (ASD) surgery can negatively impact clinical outcomes and increase risk of mechanical complications. Despite improved definition of ideal alignment for ASD surgery and increasingly sophisticated preoperative alignment planning tools, it remains unclear whether the preoperative goals for alignment are actually achieved with surgery. PURPOSE: The objective of this study was to assess whether preoperative goals for sagittal alignment following ASD surgery are consistently achieved. STUDY DESIGN/SETTING: Multicenter, prospective cohort study. PATIENT SAMPLE: Operatively treatedASD patients. OUTCOME MEASURES: Sagittal vertical axis (SVA), pelvic incidence to lumbar lordosis mismatch (PI-LL), T4-T12 thoracic kyphosis (TK).
METHOD(S): From 2018-2021, ASD patients were enrolled into a prospective ASD study based on three criteria: deformity severity (PI-LL>25degree, TPA>30degree, SVA>15cm, TCobb>70degree or TLCobb>50degree), procedure complexity (>12 levels fused, 3CO or ACR), and/or patient age (>65 and >7 levels fused). The operating surgeon documented sagittal alignment goals prior to surgery, including SVA, PI-LL mismatch and TK. Alignment goals were compared with achieved alignment at 6 weeks postop and the overall mean and SD were calculated for the offset (achieved minus goal) for each measure. Goal alignment was considered attained if the offset was within +/-1 SD of the goal. Demographic, surgical and baseline radiographic measures demonstrating significant association with achieving alignment goal on univariate analysis were used for multivariate regression analysis.
RESULT(S): The 266 enrolled patients had a mean age of 61.0 yrs (SD=14.6 yrs) and 68% were women. Mean number of instrumented levels was 13.6 (SD=3.8) and 24% had a 3-column osteotomy (3CO). Mean (SD) offsets were: SVA=-8.5 mm (45.6 mm), PI-LL=-4.6degree (14.6degree), TK=7.2degree (14.7degree), reflecting a tendency to undercorrect SVA and PI-LL relative to goal and to increase TK relative to goal. Surgeons achieved goal alignment (within 1 SD) for SVA, PI-LL, and TK in 74.4%, 71.4%, and 68.8% of cases, respectively. On regression analysis: goal SVA was more likely to be achieved with lower baseline SVA (OR=0.993, 95%CI=0.988-0.997, p=0.001) and greater baseline TK (OR=1.016, 95%CI=1.002-1.031, p=0.029); goal PI-LL was more likely to be achieved with greater patient age (OR=1.021, 95%CI=1.002-1.039, p=0.026) and history of previous TL spine surgery (OR=2.028, 95% CI=1.136-3.621, p=0.017); and goal TK was more likely to be achieved with lower baseline SVA (OR=0.995, 95%CI=0.991-0.999; p=0.014). The proportions of patients with achieved alignment within 1 SD of goal were not significantly different for patients with a UIV above T7 vs those with a UIV at or below T7 for SVA (p=0.20), PI-LL (p=0.49) or TK (p=0.06). Notably, patient-specific rods were used in 21 patients and were not associated with greater achievement of goal alignment for any parameter (p>0.8), with similar tendencies to undercorrect SVA and PI-LL and increase TK (p>0.6).
CONCLUSION(S): Surgeons failed to achieve goal alignment of each sagittal parameter in ~25% of patients operated for ASD, with a tendency to undercorrect SVA and PI-LL and increase TK. Patients at greatest risk tended to be those with more severe baseline deformity. Further advancements are needed to enable more consistent translation of preoperative alignment planning to the operating room. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: A previous study by Pellise 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.
METHOD(S): 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.
RESULT(S): 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.
CONCLUSION(S): 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.
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BACKGROUND CONTEXT: 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. PURPOSE: To assess the incidence of TD following ASD-corrective surgery in comparison with the occurrence of PJK. STUDY DESIGN/SETTING: Retrospective cohort. PATIENT SAMPLE: A total of 689 ASD patients. OUTCOME MEASURES: ASD, TD, PJK, thoracic compensation.
METHOD(S): ASD patients with complete baseline (BL) and two-year (2Y) followup were included. Patients were divided into groups: those who developed TD: T4-T12 >54.2degree 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.
RESULT(S): 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).
CONCLUSION(S): 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. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: 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. PURPOSE: To assess the impact of artificial intelligence on peri- and postoperative course in minimally-invasive adult spinal deformity corrective surgery. STUDY DESIGN/SETTING: Retrospective cohort review. PATIENT SAMPLE: This study included 524 MIS patients. OUTCOME MEASURES: Intra- and postoperative complication rates; reoperation rate; HRQLs METHODS: 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.
RESULT(S): 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).
CONCLUSION(S): 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. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Adult spinal deformity (ASD) patients undergoing surgery risk neurological decline following surgery. However, surgery may be the key in improving outcomes in patients starting with lower extremity motor deficits at baseline (BL). We aim to analyze the improvement in neurological outcomes of ASD patients undergoing spinal reconstruction with BL and 6-week postoperative lower extremity motor scores (LEMS). PURPOSE: The aim of this study is to analyze the improvement in neurological outcomes of adult patients undergoing deformity surgery with baseline abnormal LEMS. STUDY DESIGN/SETTING: Multicenter, prospective cohort. PATIENT SAMPLE: A total of 205 patients were included in the study. OUTCOME MEASURES: Patient and procedural factors that lead to the improvement in neurological outcomes of adult patients undergoing deformity surgery with baseline abnormalLEMS.
METHOD(S): ASD patients ages = 18 were prospectively studied from 2018-2021. All patients underwent an instrumented PSF with a few also having an ASF of the lumbar spine. Patients were dichotomized based on BL LEMS (NML = 50, ABML < 50). The ABNML group was then dichotomized based on whether LEMS improved overall from BL or experienced no change or declined by first postoperative follow-up (PO) and various factors were analyzed and compared using standard statistical tests.
RESULT(S): Of the 205 patients evaluated, 134 (65.4%) were NML and 71 were ABNML (34.3%) at BL. Among the 71 patients with ABML LEMS at BL, 49% (N=35) improved to NML levels, 21% (N=15) improved from BL levels but not to NML, 20% (N=14) remained the same, and 10% (N=7) declined further at 6week PO. Compared to ABNML patients with no change or a decline in LEMS at first PO, patients who improved overall (70%; N=50) had significantly more decompressions performed (86% vs 57%; p=0.0092), and had more PCOs performed intraoperatively (90% vs 62%, p=0.0074). There were no statistical differences between the groups in age, BL LEMS, BMI, total instrumented vertebrae (TIV), EBL, and OR time. Overall, the number of patients with NML LEMS at 6 weeks PO increased by 7.5% (65.4% to 70.2%; p<.0001).
CONCLUSION(S): Seventy percent of patients with ABML LEMS at BL improved their motor strength by the first PO visit, while 30% stayed the same or declined. ABNML patients who improved from BL had significantly more decompressions performed and, surprisingly, more PCOs performed. Interestingly, patient factors between the two groups demonstrated no statistical differences further highlighting that improvement may be influenced by the differences in surgical techniques. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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