Faculty Bibliography

OBJECTIVE:Circumferential minimally invasive surgery (cMIS) may provide incremental benefits compared with open surgery for patients with increasing frailty status by decreasing peri- and postoperative complications. METHODS:Operative patients with adult spinal deformity (ASD) ≥ 18 years old with baseline and 2-year postoperative data were assessed. With propensity score matching, patients who underwent cMIS (cMIS group) were matched with similar patients who underwent open surgery (open group) based on baseline BMI, C7-S1 sagittal vertical axis, pelvic incidence to lumbar lordosis mismatch, and S1 pelvic tilt. The Passias modified ASD frailty index (mASD-FI) was used to determine patient frailty stratification as not frail, frail, or severely frail. Baseline and postoperative factors were assessed using two-way analysis of covariance (ANCOVA) and multivariate ANCOVA while controlling for baseline age, Charlson Comorbidity Index (CCI) score, and number of levels fused. RESULTS:After propensity score matching, 170 ASD patients (mean age 62.71 ± 13.64 years, 75.0% female, mean BMI 29.25 ± 6.60 kg/m2) were included, split evenly between the cMIS and open groups. Surgically, patients in the open group had higher numbers of posterior levels fused (p = 0.021) and were more likely to undergo three-column osteotomies (p > 0.05). Perioperatively, cMIS patients had lower intraoperative blood loss and decreased use of cell saver across frailty groups (with adjustment for baseline age, CCI score, and levels fused), as well as fewer perioperative complications (p < 0.001). Adjusted analysis also revealed that compared to open patients, increasingly frail patients in the cMIS group were also more likely to demonstrate greater improvement in 1- and 2-year postoperative scores for the Oswestry Disability Index, SRS-36 (total), EQ-5D and SF-36 (all p < 0.05). With regard to postoperative complications, increasingly frail patients in the cMIS group were also noted to experience significantly fewer complications overall (p = 0.036) and fewer major intraoperative complications (p = 0.039). The cMIS patients were also less likely to need a reoperation than their open group counterparts (p = 0.043). CONCLUSIONS:Surgery performed with a cMIS technique may offer acceptable outcomes, with diminishment of perioperative complications and mitigation of catastrophic outcomes, in increasingly frail patients who may not be candidates for surgery using traditional open techniques. However, further studies should be performed to investigate the long-term impact of less optimal alignment in this population.

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:Construct an individualized cervical realignment strategy based on patient parameters at the presentation that results in superior 2-year health-related quality of life metrics and decreased rates of junctional failure and reoperation following adult cervical deformity surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:Research has previously focused on adult cervical deformity realignment thresholds for maximizing clinical outcomes while minimizing complications. However, realignment strategies may differ based on patient presentation and clinical characteristics. METHODS:We included adult cervical deformity patients with 2-year data. The optimal outcome was defined as meeting good clinical outcomes without distal junctional failure or reoperation. Radiographic parameters assessed included C2 Slope, C2-C7, McGregor's slope, TS-CL, cSVA, T1 slope, and preoperative lowest-instrumented vertebra (LIV) inclination angle. Conditional inference trees were used to establish thresholds for each parameter based on achieving the optimal outcome. Analysis of Covariance and multivariable logistic regression analysis, controlling for age, comorbidities, baseline deformity and disability, and surgical factors, assessed outcome rates for the hierarchical approach within each deformity group. RESULTS:One hundred twenty-seven patients were included. After correction, there was a significant difference in meeting the optimal outcome when correcting the C2 slope below 10 degrees (85% vs. 34%, P <0.001), along with lower rates of distal junctional failure (DJF) (7% vs. 42%, P <0.001). Next, after isolating patients below the C2 slope threshold, the selection of LIV with an inclination between 0 and 40 degrees demonstrated lower rates of distal junctional kyphosis and higher odds of meeting optimal outcome(OR: 4.2, P =0.011). The best third step was the correction of cSVA below 35 mm. This hierarchical approach (11% of the cohort) led to significantly lower rates of DJF (0% vs. 15%, P <0.007), reoperation (8% vs. 28%, P <0.001), and higher rates of meeting optimal outcome (93% vs. 36%, P <0.001) when controlling for age, comorbidities, and baseline deformity and disability. CONCLUSION/CONCLUSIONS:Our results indicate that the correction of C2 slope should be prioritized during cervical deformity surgery, with the selection of a stable LIV and correction of cervical SVA below the idealized threshold. Among the numerous radiographic parameters considered during preoperative planning for cervical deformity correction, our determinations help surgeons prioritize those realignment strategies that maximize the health-related quality of life outcomes and minimize complications. LEVEL OF EVIDENCE/METHODS:Level-III.

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

STUDY DESIGN/METHODS:Retrospective cohort study utilizing the New York statewide planning and research cooperative system. STUDY OBJECTIVE/OBJECTIVE:To investigate postoperative complications of patients with metabolic bone disorders (MBDs) who undergo 2-3 levels of anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA/BACKGROUND:MBDs and cervical degenerative pathologies, including cervical radiculopathy (CR) and cervical myelopathy (CM), are prevalent in the aging population. Complications with ACDF procedures can lead to increased hospitalization times, more expensive overhead, and worse patient outcomes. METHOD/METHODS:Patients with CM/CR who underwent an ACDF of 2-3 vertebrae from 2009 to 2011 with a minimum 2-year follow-up were identified. Patients diagnosed with 1 or more MBD at baseline were compared with a control cohort without any MBD diagnosis. Cohorts were compared for demographics, hospital-related parameters, and 2-year medical, surgical, and overall complications. Binary multivariate logistic regression was used to identify independent predictors. RESULTS:A total of 22,276 patients were identified (MBD: 214; no-MBD: 22,062). Among MBD patients, the majority had vitamin D deficiency (n = 194, 90.7%). MBD patients were older (53.0 vs 49.7 y, P < 0.001), and with higher Deyo index (1.0 vs 0.5, P < 0.001). MBD patients had higher rates of medical complications, including anemia (6.1% vs 2.3%), pneumonia (4.7% vs 2.1%), hematoma (3.3% vs 0.7%), infection (2.8% vs 0.9%), and sepsis (3.7% vs 0.9%), as well as overall medical complications (23.8% vs 9.6%) (all, P ≤0.033). MBD patients also experienced higher surgical complications, including implant-related (5.7% vs 1.9%), wound infection (4.2% vs 1.2%), and wound disruption (0.9% vs 0.2%), and overall surgical complications (9.8% vs 3.2%) (all, P ≤0.039). Regression analysis revealed that a baseline diagnosis of MBD was independently associated with an increased risk of 2-year surgical complications (odds ratio = 2.10, P < 0.001) and medical complications (odds ratio = 1.84, P = 0.001). CONCLUSIONS:MBD as a comorbidity was associated with an increased risk of 2-year postoperative complications after 2-3 level ACDF for CR or CM.

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.

Understanding global body balance can optimize the postoperative course for patients undergoing spinal or lower limb surgical realignment. This observational cohort study aimed to characterize patients with reported imbalance and identify predictors. The CDC establishes a representative sample annually via the NHANES. All participants who said "yes" (Imbalanced) or "no" (Balanced) to the following question were identified from 1999-2004: "During the past 12 months, have you had dizziness, difficulty with balance or difficulty with falling?" Univariate analyses compared Imbalanced versus Balanced subjects and binary logistic regression modeling predicted for Imbalance. Of 9964 patients, imbalanced (26.5%) were older (65.4 vs. 60.6 years), with more females (60% vs. 48%). Imbalanced subjects reported higher rates of comorbidities, including osteoporosis (14.4% vs. 6.6%), arthritis (51.6% vs. 31.9%), and low back pain (54.4% vs 32.7%). Imbalanced patients had more difficulty with activities, including climbing 10 steps (43.8% vs. 21%) and stooping/crouching/kneeling (74.3% vs. 44.7%), and they needed greater time to walk 20 feet (9.5 vs. 7.1 s). Imbalanced subjects had significantly lower caloric and dietary intake. Regression revealed that difficulties using fingers to grasp small objects (OR: 1.73), female gender (OR: 1.43), difficulties with prolonged standing (OR: 1.29), difficulties stooping/crouching/kneeling (OR: 1.28), and increased time to walk 20 feet (OR: 1.06) were independent predictors of Imbalance (all p < 0.05). Imbalanced patients were found to have identifiable comorbidities and were detectable using simple functional assessments. Structured tests that assess dynamic functional status may be useful for preoperative optimization and risk-stratification for patients undergoing spinal or lower limb surgical realignment.

The consequences of malnutrition in spine surgery have been studied to a lesser degree compared to other orthopedic subspecialties. However, there is growing interest in understanding the effects of preoperative malnutrition on spine surgery outcomes. Literature on the relationship between malnutrition and spine surgery outcomes appeared sporadically in the late 1990s and early 2000s. Over the last decade, however, there has been a push to understand the sequelae of malnutrition on patients undergoing spine surgery. The aims of this review are to highlight: 1. the different parameters by which malnutrition has been defined and measured in spine surgery; 2. the prevalence of malnutrition in spine surgery; 3. the outcomes of spine surgery in malnourished patients; and 4. the effects of nutritional supplementation or interventions on spine surgery outcomes. Malnutrition has often been defined utilizing specific serological laboratory values or nutritional indices. Serologic values of malnutrition include an albumin < 3.5 g/dL, transferrin < 150 mg/ dL, or a total lymphocyte count of < 1,500 cells/mm3 . The available literature reports that the prevalence of malnutrition in patients undergoing lumbar spine surgery ranges from 5% to 50%, with most literature supporting a value toward the higher end of this spectrum. Malnourished patients undergoing spine surgery have higher rates of surgical site infections, medical complications, lengths of stay, ICU admissions, 30-day and 1-year mortalities, reoperations, 30-day readmissions, and costs of care. Given the plethora of spine surgeries performed in the country annually and the prevalence of malnutrition in up to 50% of our patients, we recommend performing preoperative nutritional assessments on all patients to ensure their optimization prior to surgery.

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.

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.