Faculty Bibliography

BACKGROUND CONTEXT/BACKGROUND:While the treatment of adult spinal deformity (ASD) has increasingly favored surgical correction, the incidence of revision surgery remains high. Yet, little has been explored on the association between the etiology of reoperation and patient outcomes. PURPOSE/OBJECTIVE:To assess the impact of the etiology of revision surgery on postoperative outcomes. STUDY DESIGN/SETTING/METHODS:Retrospective cohort analysis. PATIENT SAMPLE/METHODS:891 ASD patients. OUTCOME MEASURES/METHODS:Complications, radiographic parameters, disability metrics. METHODS:Operative ASD patients with at least 1 revision stratified by etiology (mechanical [Mech] -pseudoarthrosis, thoracic decompensation without junctional failure, x-ray malalignment, implant failure, implant malposition, PJK ± major malalignment; infection [Infx]-early vs late onset, major vs minor; wound [Wound]; SI pain [SI Pain]). Excluded multiple etiologies, and intraoperative or medical complications. Data from the immediate visit prior to the final revision was used as baseline (rBL). Follow-up based on visits best aligned to time points after final revision. Radiographic parameters SVA, PI-LL, and PT were used to assess alignment post-revision via ANOVA. Multivariate analysis controlling for relevant covariates assessed outcome differences after final revision surgery. RESULTS:891 MET INCLUSION (AGE: 60.40±14.17, 77% F, BMI: 27.97±5.87 KG/M2, CCI: : 1.80±1.73). Etiology groups were as follows: Mech: 432; Infx: 296; Wound: 65; SI Pain: 98. Surgically, Infx had lower rates of osteotomy, interbody fusion, and decompression (p<.05). Infx and SI Pain demonstrated similar correction in radiographics SVA, PI-LL, and PT (p>.05), whereas Mech had significantly less improvement by 2 years (p<.003) that improved by 5 years. Compared to without revision, the odds of MCID in ODI were 48.6% lower across groups (OR: 0.514 [.280, .945], p=.032). Indications of x-ray malalignment were 93.0% less likely to reach MCID (OR: 0.071, [.006, .866], p=.038). Similarly, implant failure negatively impacted rates of MCID (40% vs. 15.2%, p=.029). Those with PJK had 57% lower odds of MCID (33% vs 54%, OR: .43, [0.2, 0.9] p= 0.023), further negated by major malalignment (OR: 0.05, [.07, .97], p=.02). Indications of pseudarthrosis, thoracic decompensation, implant malposition were not significant. Major sepsis had lower rates of MCID compared to minor (6.4% vs. 21.2%), and early onset infection improved compared to late (OR: 1.43, [1.17, 2.98], p<.001). In the early follow-up period, the Mech group has significantly worse SRS Pain and Mental Health scores compared to other groups (1-year: Mech 1.56 vs Infx 0.83 vs SI Pain 0.72, p<0.001; 2-year: 1.88 vs 0.71 vs 0.76, p=0.034). Complication rates increased with the number of revisions and with mechanical indication (all p<.05). At 5 years, patient satisfaction was significantly more likely to improve compared to early follow-up (OR: 1.22, p=.011), along with improved pain score, in Mech group (0.89 vs 0.49 vs 0.56, p=.081). CONCLUSIONS:This study focused on the impact of revision as it varies with etiology and time of occurrence postoperatively. Compared to other etiologies, revision surgery due to mechanical complications had less radiographic improvement and worsening patient-reported scores in the early postoperative period despite stabilization at 5 years. The depth of impact of mechanical complication, particularly with the addition of malalignment, merits greater focus during surgical planning. LEVEL OF EVIDENCE/METHODS:III.

STUDY DESIGN/METHODS:Retrospective analysis of prospectively collected data. OBJECTIVE:Evaluate the impact of prior cervical constructs on upper instrumented vertebrae (UIV) selection and postoperative outcomes among patients undergoing thoracolumbar deformity correction. BACKGROUND:Surgical planning for adult spinal deformity (ASD) patients involves consideration of spinal alignment and existing fusion constructs. METHODS:ASD patients with (ANTERIOR or POSTERIOR) and without (NONE) prior cervical fusion who underwent thoracolumbar fusion were included. Demographics, radiographic alignment, patient-reported outcome measures (PROMs), and complications were compared. Univariate and multivariate analyses were performed on POSTERIOR patients to identify parameters predictive of UIV choice and to evaluate postoperative outcomes impacted by UIV selection. RESULTS:Among 542 patients, with 446 NONE, 72 ANTERIOR, and 24 POSTERIOR patients, mean age was 64.4 years and 432 (80%) were female. Cervical fusion patients had worse preoperative cervical and lumbosacral deformity, and PROMs (P<0.05). In the POSTERIOR cohort, preoperative LIV was frequently below the cervicothoracic junction (54%) and uncommonly (13%) connected to the thoracolumbar UIV. Multivariate analyses revealed that higher preoperative cervical SVA (coeff=-0.22, 95%CI=-0.43--0.01, P=0.038) and C2SPi (coeff=-0.72, 95%CI=-1.36--0.07, P=0.031), and lower preoperative thoracic kyphosis (coeff=0.14, 95%CI=0.01-0.28, P=0.040) and thoracolumbar lordosis (coeff=0.22, 95%CI=0.10-0.33, P=0.001) were predictive of cranial UIV. Two-year postoperatively, cervical patients continued to have worse cervical deformity and PROMs (P<0.05) but had comparable postoperative complications. Choice of thoracolumbar UIV below or above T6, as well as the number of unfused levels between constructs, did not affect patient outcomes. CONCLUSIONS:Among patients who underwent thoracolumbar deformity correction, prior cervical fusion was associated with more severe spinopelvic deformity and PROMs preoperatively. The choice of thoracolumbar UIV was strongly predicted by their baseline cervical and thoracolumbar alignment. Despite their poor preoperative condition, these patients still experienced significant improvements in their thoracolumbar alignment and PROMs after surgery, irrespective of UIV selection. LEVEL OF EVIDENCE/METHODS:IV.

BACKGROUND:Recombinant human bone morphogenetic protein-2 (rhBMP-2) has not shown superior benefit overall in cost-effectiveness during adult spinal deformity (ASD) surgery. STUDY DESIGN/SETTING/METHODS:Retrospective PURPOSE: Generate a risk score for pseudarthrosis to inform the utilization of rhBMP-2, balancing costs against quality of life and complications. METHODS:ASD patients with 3-year data were included. Quality of life gained was calculated from ODI to SF-6D and translated to quality-adjusted life years (QALYs). Cost was calculated using the PearlDiver database and CMS definitions for complications and comorbidities. Established weights were generated for predictive variables via logistic regression to yield a predictive risk score for pseudarthrosis that accounted for frailty, diabetes, depression, ASA grade, thoracolumbar kyphosis and three-column osteotomy use. Risk score categories, established via conditional inference tree (CIT)-derived thresholds were tested for cost-utility of rhBMP-2 usage, controlling for age, prior fusion, and baseline deformity and disability. RESULTS:64% of ASD patients received rhBMP-2 (308/481). There were 17 (3.5%) patients that developed pseudarthrosis. rhBMP-2 use overall did not lower pseudarthrosis rates (OR: 0.5, [0.2-1.3]). Pseudarthrosis rates for each risk category were: No Risk (NoR) 0%; Low-Risk (LowR) 1.6%; Moderate Risk (ModR) 9.3%; High-Risk (HighR) 24.3%. Patients receiving rhBMP-2 had similar QALYs overall to those that did not (0.163 vs. 0.171, p = .65). rhBMP-2 usage had worse cost-utility in the LowR cohort (p < .001). In ModR patients, rhBMP-2 usage had equivocal cost-utility ($53,398 vs. $61,581, p = .232). In the HighR cohort, the cost-utility was reduced via rhBMP-2 usage ($98,328 vs. $211,091, p < .001). CONCLUSION/CONCLUSIONS:Our study shows rhBMP-2 demonstrates effective cost-utility for individuals at high risk for developing pseudarthrosis. The generated score can aid spine surgeons in the assessment of risk and enhance justification for the strategic use of rhBMP-2 in the appropriate clinical contexts. LEVEL OF EVIDENCE/METHODS:III.

PURPOSE/OBJECTIVE:To evaluate the variability in intraoperative fluid management during adult spinal deformity (ASD) surgery, and analyze the association with complications, intensive care unit (ICU) requirement, and length of hospital stay (LOS). METHODS:Multicenter comparative cohort study. Patients ≥ 18 years old and with ASD were included. Intraoperative intravenous (IV) fluid data were collected including: crystalloids, colloids, crystalloid/colloid ratio (C/C), total IV fluid (tIVF, ml), normalized total IV fluid (nIVF, ml/kg/h), input/output ratio (IOR), input-output difference (IOD), and normalized input-output difference (nIOD, ml/kg/h). Data from different centers were compared for variability analysis, and fluid parameters were analyzed for possible associations with the outcomes. RESULTS:Seven hundred ninety-eight patients with a median age of 65.2 were included. Among different surgical centers, tIVF, nIVF, and C/C showed significant variation (p < 0.001 for each) with differences of 4.8-fold, 3.7-fold, and 4.9-fold, respectively. Two hundred ninety-two (36.6%) patients experienced at least one in-hospital complication, and ninety-two (11.5%) were IV fluid related. Univariate analysis showed significant relations for: LOS and tIVF (ρ = 0.221, p < 0.001), IOD (ρ = 0.115, p = 0.001) and IOR (ρ = -0.138, p < 0.001); IV fluid-related complications and tIVF (p = 0.049); ICU stay and tIVF, nIVF, IOD and nIOD (p < 0.001 each); extended ICU stay and tIVF (p < 0.001), nIVF (p = 0.010) and IOD (p < 0.001). Multivariate analysis controlling for confounders showed significant relations for: LOS and tIVF (p < 0.001) and nIVF (p = 0.003); ICU stay and IOR (p = 0.002), extended ICU stay and tIVF (p = 0.004). CONCLUSION/CONCLUSIONS:Significant variability and lack of standardization in intraoperative IV fluid management exists between different surgical centers. Excessive fluid administration was found to be correlated with negative outcomes. LEVEL OF EVIDENCE/METHODS:III.

BACKGROUND/UNASSIGNED:While prolonged operative time and increased levels fused have been shown to increase the risk of prolonged intensive care unit (ICU) length-of-stay (LOS), studies are limited in guiding decision-making regarding the need for intensive care postoperatively. This is especially the case among the cohort of adolescent idiopathic scoliosis (AIS) patients undergoing posterior spinal fusion (PSF); associations between comorbidities and ICU LOS are not well-delineated. METHODS/UNASSIGNED:AIS patients who underwent PSF from January 1st, 2016 to December 1st, 2016 at 101 participating centers were identified using the American College of Surgeons (ACS) National Surgical Quality Im-provement Project (NSQIP) Pediatric database. Patients were subsequently grouped by ICU LOS 0-1 day; 2-3 days; and >3 days. Multivariate regression identified predictors of increased ICU LOS. RESULTS/UNASSIGNED:2,346 AIS patients were included. The >3 days and 2-3 days groups had higher asthma rates compared to 0-1 day. The >3 days group had higher rates of structural airway abnormalities and he-matologic disorders. Cognitive impairment rates were highest for >3-day ICU LOS. Hematologic dis-orders, structural airway abnormalities, asthma and cognitive impairment were associated with prolonged ICU LOS. CONCLUSION/UNASSIGNED:.

BACKGROUND:Tranexamic acid (TXA) is commonly utilized to reduce blood loss in adult spinal deformity (ASD) surgery. Despite its widespread use, there is a lack of consensus regarding the optimal dosing regimen. The aim of this study was to assess differences in blood loss and complications between high, medium, and low-dose TXA regimens among patients undergoing surgery for complex ASD. METHODS:A multicenter database was retrospectively analyzed to identify 265 patients with complex ASD. Patients were separated into 3 groups by TXA regimen: (1) low dose (<20-mg/kg loading dose with ≤2-mg/kg/hr maintenance dose), (2) medium dose (20 to 50-mg/kg loading dose with 2 to 5-mg/kg/hr maintenance dose), and (3) high dose (>50-mg/kg loading dose with ≥5-mg/kg/hr maintenance dose). The measured outcomes included blood loss, complications, and red blood cell (RBC) units transfused intraoperatively and perioperatively. The multivariable analysis controlled for TXA dosing regimen, levels fused, operating room time, preoperative hemoglobin, 3-column osteotomy, and posterior interbody fusion. RESULTS:The cohort was predominantly White (91.3%) and female (69.1%) and had a mean age of 61.6 years. Of the 265 patients, 54 (20.4%) received low-dose, 131 (49.4%) received medium-dose, and 80 (30.2%) received high-dose TXA. The median blood loss was 1,200 mL (interquartile range [IQR], 750 to 2,000). The median RBC units transfused intraoperatively was 1.0 (IQR, 0.0 to 2.0), and the median RBC units transfused perioperatively was 2.0 (IQR, 1.0 to 4.0). Compared with the high-dose group, the low-dose group had increased blood loss (by 513.0 mL; p = 0.022) as well as increased RBC units transfused intraoperatively (by 0.6 units; p < 0.001) and perioperatively (by 0.3 units; p = 0.024). The medium-dose group had increased blood loss (by 491.8 mL; p = 0.006) as well as increased RBC units transfused intraoperatively (by 0.7 units; p < 0.001) and perioperatively (by 0.5 units; p < 0.001) compared with the high-dose group. CONCLUSIONS:Patients with ASD who received high-dose intraoperative TXA had fewer RBC transfusions intraoperatively, fewer RBC transfusions perioperatively, and less blood loss than those who received low or medium-dose TXA, with no differences in the rates of seizure or thromboembolic complications. LEVEL OF EVIDENCE/METHODS:Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

STUDY DESIGN/METHODS:Retrospective cohort study of a prospectively collected single-center database. OBJECTIVE:Distal Junctional Kyphosis (DJK) is one of the most common complications in adult cervical deformity (ACD) correction. The utility of radiographic alignment alone in predicting and minimizing DJK occurrence warrants further study. To investigate the impact of post-operative radiographic alignment on development of DJK in ACD patients. METHODS:ACD patients (≥18 yrs) with complete baseline (BL) and two-year (2Y) radiographic data were included. DJF was defined as DJK greater than 15° (Passias et al) or DJK with reop. Multivariable logistic regression (MVA) identified 3-month predictors of DJK. Conditional inference tree (CIT) machine learning analysis determined threshold cutoffs. Radiographic predictors were combined in a model to determine predictive value using area under the curve (AUC) methodology. "Match" refers to ideal age-adjusted alignment. RESULTS:< .05) were significant predictors of a lower likelihood of DJK. Receiver operator curve AUC using age, T1S match, TS-CL match, LL-TK match, cSVA <3.7 cm, and T4-T12 <50 predicted DJK with an AUC of .91 for DJK by 2Y, and .88 for DJF by 2Y. CONCLUSION/CONCLUSIONS:These findings suggest post-operative radiographic alignment is strongly associated with distal junctional kyphosis. When utilizing age-adjusted realignment in addition to newly developed thresholds, a suggested post-operative cSVA target of 3.7 cm and thoracic kyphosis less than 50, it is possible to substantially reduce the occurrence of distal junctional kyphosis and distal junctional failure.

BACKGROUND:Adult cervical deformity (ACD) surgery is more frequently being performed in frail patients. Although surgical outcomes are largely successful, there remains significant risk of poor outcomes. The ideal length of fusion constructs in these patients remains debatable. METHODS:Patients undergoing cervical fusion for ACD with lower instrumented vertebra (LIV) at T4-or-above, with clinical and radiographic data from baseline (BL) to 2 years (2Y) were stratified by CD-modified frailty index into not frail (NF), frail (F) and severely frail (SF) categories. Deformity was classified by Kim et al. criteria. Means comparisons tests were used to assess differences between both groups. Logistic regression analyses were used to analyze associations between frailty categories, lower instrumented vertebra (LIV) and outcomes. RESULTS:286 patients (Age: 57.3 ± 10.9 years, BMI: 28.9 ± 6.4 kg/m2, CCI: 0.84 ± 1.26). 47% of patients were female. 32.2% of patients were NF, 50.3% F and 17.5% SF. By deformity, 66% were focal kyphosis (FK), 12% were flatneck, and 22% were cervicothoracic. Only FK type differed between NF and F/SF patients (39.2 vs 73.6%, p = 0.005). At baseline (BL), differences in age, BMI, CCI and deformity were not significant. F/SF patients had longer LOS (p = 0.018) and higher rates of distal junctional kyphosis/failure (DJK/F) at 2 years. Controlling for baseline disability, F and SF patients were more likely to experience poor outcomes at 2 years with C7 compared with more distal LIVs. The risk for poorer outcomes was not significant when comparing LIVs within the upper thoracic spine. Similar trends were seen performing sub-analyses specifically comparing F vs SF patients. CONCLUSIONS:Frail patients are at risk for poor outcomes following ACD surgery due to their comorbidities. These patients appear to be at even greater risk for poor outcomes with a lower instrumented vertebra proximal to T1.