Faculty Bibliography

BACKGROUND:The prevalence of malnutrition in patients undergoing lumbar spine surgery ranges from 5-50%, and is associated with higher rates of surgical site infections, medical complications, longer lengths of stay, and mortality. PURPOSE/OBJECTIVE:Determine if perioperative nutritional intervention decreases wound healing complications in patients undergoing lumbar spine surgery. STUDY DESIGN/SETTING/METHODS:Prospective RCT. METHODS:Patients aged 55+ undergoing elective primary lumbar surgery were included. Patients with a preoperative albumin<3.5 g/dL were defined as malnourished. Intervention group received nutritional supplementation(protein shake) twice daily from postoperative day 0 to two weeks post-discharge. Control group was instructed to continue regular daily diets. Primary outcomes included minor in-hospital complications(wound drainage,electrolyte abnormalities,hypotension,ileus,deep venous thrombus) and wound healing complications within 90 days. Secondary outcomes included 90-day Emergency Room(ER) visits, readmissions, and return to the operating room(OR). Baseline data were compared between groups using means comparison tests. Multivariable analysis evaluated association of outcomes with nutritional supplementation. Sub-analysis of malnourished patients assessed effects of nutritional supplementation on outcomes. RESULTS:One-hundred three patients were included. Thirty-seven(35.9%) were considered malnourished preoperatively. Forty-six(44.7%) received nutritional intervention and 57(55.3%) served as controls. Adjusted analysis found patients receiving supplementation had lower rates of in-hospital minor complications(2.1% vs. 23.2%,P<0.01), and perioperative wound healing complications(3.4% vs. 17.9%,P<0.05). Sub-group analysis of 37 malnourished patients demonstrated that malnourished patients who received perioperative nutritional supplementation had lower rates of minor complications during admission(0.0% vs. 34.4%,P=0.01) and return to the OR within 90 days(0.0% vs. 12.4%,P=0.04). CONCLUSION/CONCLUSIONS:Over one-third of patients undergoing lumbar surgery were malnourished. Nutritional supplementation during the two-week perioperative period decreased rates of minor complications during admission and wound complications within 90 days. Malnourished patients receiving supplementation less often returned to the operating room. To our knowledge, this is the first study to investigate the effects of perioperative nutritional intervention on wound healing complications for patients undergoing elective lumbar spine surgery. LEVEL OF EVIDENCE/METHODS:I.

BACKGROUND:We developed a spinal deformity complexity checklist (SDCC) to assess the difficulty in performing a circumferential minimally invasive surgery (MIS) for adult spinal deformity. METHODS:A modified Delphi method of panel experts was used to construct an SDCC checklist of radiographic and patient-related characteristics that could affect the complexity of surgery via MIS approaches. Ten surgeons with expertise in MIS deformity surgery were queried to develop and refine the SDCC with 3 radiographic categories (x-ray, magnetic resonance imaging, computed tomography) and 1 patient-related category. Within each category, characteristics affecting MIS complexity were identified by initial roundtable discussion. Second-round discussion determined which characteristics substantially impacted complexity the most. RESULTS:Thirteen characteristics within the x-ray category were determined. Spinopelvic characteristics, endpoints of instrumentation, and prior hardware/fusion were associated with increased complexity. Vertebral body rotation-as reflected by the Nash-Moe grade-added significant complexity. Psoas anatomy and spinal stenosis added the most complexity for the 5 magnetic resonance imaging characteristics. There were 3 characteristics in the CT category with pre-exisiting fusion, being the variable most highly selected. Of the 5 patient-related characteristics, osteoporosis and BMI were found to most affect complexity. CONCLUSIONS:The SDCC is a comprehensive list of pertinent radiographic and patient-related characteristics affecting complexity level for MIS deformity surgery. The value of the SDCC is that it allows rapid assessment of key factors when determining whether MIS surgery can be performed effectively and safely. Patients with scores of 4 in any characteristic should be considered challenging to treat with MIS; open surgery may be a better alternative.

OBJECTIVE:The objective of this study was to use an unsupervised cluster approach to identify patterns of operative adult spinal deformity (ASD) and compare the perioperative outcomes of these groups. METHODS:A multicenter data set included patients with complex surgical ASD, including those with severe deformities, significant surgical complexity, or advanced age who underwent a multilevel fusion. An unsupervised cluster analysis allowing for 10% outliers was used to identify different deformity patterns. The perioperative outcomes of these clusters were then compared using ANOVA, Kruskal-Wallis, and chi-square tests, with p values < 0.05 considered significant. RESULTS:Two hundred eighty-six patients were classified into four clusters of deformity patterns: hyper-thoracic kyphosis (hyper-TK), severe coronal, severe sagittal, and moderate sagittal. Hyper-TK patients had the lowest disability (mean Oswestry Disability Index [ODI] 32.9 ± 17.1) and pain scores (median numeric rating scale [NRS] back score 6, leg score 1). The severe coronal cluster had moderate functional impairment (mean physical component score 34.4 ± 12.3) and pain (median NRS back score 7, leg score 4) scores. The severe sagittal cluster had the highest levels of disability (mean ODI 49.3 ± 15.6) and low appearance scores (mean 2.3 ± 0.7). The moderate cluster (mean 68.8 ± 7.8 years) had the highest pain interference subscores on the Patient-Reported Outcomes Measurement Information System (mean 65.2 ± 5.8). Overall 30-day adverse events were equivalent among the four groups. Fusion to the pelvis was most common in the moderate sagittal (89.4%) and severe sagittal (97.5%) clusters. The severe coronal cluster had more osteotomies per case (median 11, IQR 6.5-14) and a higher rate of 30-day implant-related complications (5.5%). The severe sagittal and hyper-TK clusters had more three-column osteotomies (43% and 32.3%, respectively). Hyper-TK patients had shorter hospital stays. CONCLUSIONS:This cohort of patients with complex ASD surgeries contained four natural clusters of deformity, each with distinct perioperative outcomes.

STUDY DESIGN/SETTING/METHODS:Retrospective review of a prospectively collected database. OBJECTIVE:The objective of this study was to determine the relationship between paracervical muscle area, density, and fat infiltration and cervical alignment among patients presenting with cervical spine pathology. BACKGROUND CONTEXT/BACKGROUND:The impact of cervical spine alignment on clinical outcomes has been extensively studied, but little is known about the association between spinal alignment and cervical paraspinal musculature. METHODS:We examined computed tomography scans and radiographs for patients presenting with cervical spine pathology. The posterior paracervical muscle area, density, and fat infiltration was calculated on axial slices at C2, C4, C6, and T1. We measured radiographic parameters including cervical sagittal vertical axis, cervical lordosis, T1 slope (T1S), range of motion of the cervical spine. We performed Pearson correlation tests to determine if there were significant relationships between muscle measurements and alignment parameters. RESULTS:The study included 51 patients. The paracervical muscle area was higher for males at C2 (P=0.005), C4 (P=0.001), and T1 (P=0.002). There was a positive correlation between age and fat infiltration at C2, C4, C6, and T1 (all P<0.05). The cervical sagittal vertical axis positively correlated with muscle cross-sectional area at C2 (P=0.013) and C4 (P=0.013). Overall cervical range of motion directly correlated with muscle density at C2 (r=0.48, P=0.003), C4 (r=0.41, P=0.01), and C6 (r=0.53. P<0.001) and indirectly correlated with fat infiltration at C2 (r=-0.40, P=0.02), C4 (r=-0.32, P=0.04), and C6 (r=-0.35, P=0.02). Muscle density correlated directly with reserve of extension at C2 (r=0.57, P=0.009), C4 (r=0.48, P=0.037), and C6 (r=0.47, P=0.033). Reserve of extension indirectly correlated with fat infiltration at C2 (r=0.65, P=0.006), C4 (r=0.47, P=0.037), and C6 (r=0.48, P=0.029). CONCLUSIONS:We have identified specific changes in paracervical muscle that are associated with a patient's ability to extend their cervical spine.

BACKGROUND:Patients with less severe adult spinal deformity undergo surgical correction and often achieve good clinical outcomes. However, it is not well understood how much clinical improvement is due to sagittal correction rather than treatment of the spondylotic process. PURPOSE/OBJECTIVE:Determine baseline thresholds in radiographic parameters that, when exceeded, may result in substantive clinical improvement from surgical correction. STUDY DESIGN/METHODS:Retrospective. METHODS:ASD patients with BL and 2-year(2Y) data were included. Parameters assessed: SVA, PI-LL, PT, T1PA, L1PA, L4-S1 Lordosis, C2-C7 SVA(cSVA), C2-T3, C2 Slope(C2S). Outcomes: Good Outcome(GO) at 2Y: [Meeting either: 1) SCB for ODI(change greater than 18.8), or 2) ODI<15 and SRS-Total>4.5. Binary logistic regression assessed each parameter to determine if correction was more likely needed to achieve GO. Conditional inference tree(CIT) run machine learning analysis generated baseline thresholds for each parameter, above which, correction was necessary to achieve GO. RESULTS:We included 431 ASD patients. There were 223(50%) that achieved a GO by two years. Binary logistic regression analysis demonstrated, with increasing baseline severity in deformity, sagittal correction was more often seen in those achieving GO for each parameter(all P<0.001). Of patients with baseline T1PA above the threshold, 95% required correction to meet Good Outcome(95% vs. 54%,P<0.001). A baseline PI-LL above 10° (74% of patients meeting GO) needed correction to achieve GO (OR: 2.6,[95% CI 1.4-4.8]). A baseline C2 slope above 15° also necessitated correction to obtain clinical success (OR: 7.7,[95% CI 3.7-15.7]). CONCLUSION/CONCLUSIONS:Our study highlighted point may be present at which sagittal correction has an outsized influence on clinical improvement, reflecting the line where deformity becomes a significant contributor to disability. These new thresholds give us insight into which patients may be more suitable for sagittal correction, as opposed to intervention for the spondylotic process only, leading to a more efficient utility of surgical intervention for adult spinal deformity. LEVEL OF EVIDENCE/METHODS:III.

STUDY DESIGN/METHODS:Retrospective cohort. 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. METHODS:ASD patients who received surgery between 2008-19 were included. ANCOVA was used to marginal means for outcome measures (complication rates, reoperations, HRQLs, total cost, utility gained, 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 DRG codes, limiting revisions to those within 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 $3,194 (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/CONCLUSIONS: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.

Prematurity is associated with surgical complications. This study sought to determine the risk of prematurity on 30-day complications, reoperations, and readmissions following ≥7-level PSF for AIS which has not been established. Utilizing the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP)-Pediatric dataset, all AIS patients undergoing ≥7-level PSF from 2012"“2016 were identified. Cases were 1:1 propensity score-matched to controls by age, sex, and number of spinal levels fused. Prematurity sub-classifications were also evaluated: extremely (<28 weeks), very (28"“31 weeks), and moderate-to-late (32"“36 weeks) premature. Univariate analysis with post hoc Bonferroni compared demographics, hospital parameters, and 30-day outcomes. Multivariate logistic regression identified independent predictors of adverse 30-day outcomes. 5531 patients (term = 5099; moderate-to-late premature = 250; very premature = 101; extremely premature = 81) were included. Premature patients had higher baseline rates of multiple individual comorbidities, longer mean length of stay, and higher 30-day readmissions and infections than the term cohort. Thirty-day readmissions increased with increasing prematurity. Very premature birth predicted UTIs, superficial SSI/wound dehiscence, and any infection, and moderate-to-late premature birth predicted renal insufficiency, deep space infections, and any infection. Prematurity of AIS patients differentially impacted rates of 30-day adverse outcomes following ≥7-level PSF. These results can guide preoperative optimization and postoperative expectations.

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/CONCLUSIONS: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.

STUDY DESIGN/METHODS:Retrospective review of a multicenter comprehensive cervical deformity (CD) database. OBJECTIVE:To develop a novel risk index specific to each patient to aid in patient counseling and surgical planning to minimize postop DJK occurrence. BACKGROUND:Distal junctional kyphosis(DJK) is a radiographic finding identified after patients undergo instrumented spinal fusions which can result in sagittal spinal deformity, pain and disability, and potentially neurological compromise. DJK is considered multifactorial in nature and there is a lack of consensus on the true etiology of DJK. METHODS:CD pts with baseline(BL) and at least 1-year postoperative(1Y) radiographic follow-up were included. A patient-specific DJK score was created through use of unstandardized Beta weights of a multivariate regression model predicting DJK(end of fusion construct to the 2nd distal vertebra change in this angle by<-10° from BL to postop). RESULTS:110 CD pts included(61yrs, 66.4%F, 28.8kg/m2). 31.8% of these pts developed DJK (16.1% 3M, 11.4% 6M, 62.9% 1Y). At BL, DJK pts were more frail and underwent combined approach more (both P<0.05). Multivariate model regression analysis identified individualized scores through creation of a DJK equation: -0.55+0.009(BL Inclination) -0.078(Pre Inflection)+5.9×10-5(BL LIV angle) + 0.43(combine approach) - 0.002(BL TS-CL)- 0.002(BL PT)- 0.031(BL C2-C7)+ 0.02(∆T4-T12)+ 0.63(Osteoporosis)- 0.03(anterior approach) - 0.036( Frail) - 0.032(3 column osteotomy). This equation has a 77.8% accuracy of predicting DJK. A score ≥81 predicted DJK with an accuracy of 89.3%. The BL reference equation correlated with 2Y outcomes of NSR-Back percentage(P=0.003), reoperation(P=0.04), and MCID for EQ. 5D(P=0.04). CONCLUSIONS:This study proposes a novel risk index of DJK development that focuses on potentially modifiable surgical factors as well as established patient-related and radiographic determinants. The reference model created demonstrated strong correlations with relevant two year outcome measures, including axial pain-related symptoms, occurrence of related reoperations, and the achievement of minimal clinically importance differences for EQ. 5D.