Faculty Bibliography

BACKGROUND:Frailty is a relatively new area of study for patients with cervical deformity (CD). As of yet, little is known of how operative intervention influences frailty status for patients with CD. OBJECTIVE:To investigate drivers of postoperative frailty score and variables within the cervical deformity frailty index (CD-FI) algorithm that have the greatest capacity for change following surgery. METHODS:Descriptive analysis of the cohort were performed, paired t-tests determined significant baseline to 1 yr improvements of factors comprising the CD-FI. Pearson bivariate correlations identified significant associations between postoperative changes in overall CD-FI score and CD-FI score components. Linear regression models determined the effect of successful surgical intervention on change in frailty score. RESULTS:A total of 138 patients were included with baseline frailty scores of 0.44. Following surgery, mean 1-yr frailty score was 0.27. Of the CD-FI variables, 13/40 (32.5%) were able to improve with surgery. Frailty improvement was found to significantly correlate with baseline to 1-yr change in CBV, PI-LL, PT, and SVA C7-S1. HRQL CD-FI components reading, feeling tired, feeling exhausted, and driving were the greatest drivers of change in frailty. Linear regression analysis determined successful surgical intervention and feeling exhausted to be the greatest significant predictors of postoperative change in overall frailty score. CONCLUSION/CONCLUSIONS:Complications, correction of sagittal alignment, and improving a patient's ability to read, drive, and chronic exhaustion can significantly influence postoperative frailty. This analysis is a step towards a greater understanding of the relationship between disability, frailty, and surgery in CD.

INTRODUCTION/BACKGROUND:Patient reported outcomes measurement information system (PROMIS) is a quality of life metric that has gained increased popularity due to computer adaptive testing. Previous studies have shown that PROMIS correlates with Oswestry Disability Index (ODI) in patients with back pain and takes significantly less time to complete. However, the ability of PROMIS to capture disability from spinal malalignment relative to established metrics is unknown. The aim of the present study is to validate the correlation between ODI and PROMIS in patients with back pain, analyze correlations of PROMIS and legacy metrics to sagittal alignment, and identify major drivers of PROMIS scores and ODI in patients with back pain. METHODS:A retrospective review was conducted of a prospectively collected outcome measures database (PROMIS, ODI, VAS Back, VAS Leg, VAS Neck, and VAS Arm) of spine patients > 18 years. Inclusion criteria for the present study was a chief complaint of back pain and full length weight bearing X-rays within 30 days of health related quality of life (HRQL) completion. Demographic information, radiographic alignment, psychiatric diagnoses, and comorbidities were recorded. PROMIS metrics were correlated to legacy metrics (ODI and VAS). Next, outcome metrics were correlated with sagittal alignment variables T1 Pelvic Angle (TPA), SVA, PT, and PI-LL. Patients were grouped based on the presence of spinal deformity (defined radiographically as any one of SVA > 4 cm, PI-LL > 10°, PT > 20°) and mean HRQL scores were investigated for the adult spinal deformity (ASD) and non-ASD groups. Finally, drivers of PROMIS PF scores and ODI scores were determined using multiple stepwise regression. RESULTS: = 0.376, p < 0.001). CONCLUSIONS:In a cohort of 150 patients with back pain, PROMIS correlated strongly with legacy outcome metrics, including VAS and ODI. PROMIS PF correlated more strongly with sagittal malalignment than ODI. Additionally, patients with spinal deformity had significantly worse PROMIS PF scores but similar ODI scores as patients without ASD. Finally, sagittal alignment was found to be a significant driver of PROMIS PF scores but not ODI scores. PROMIS PF should be utilized as a disability assessment tool in patients with spinal deformity due to ease of use, strong correlations with legacy metrics, and ability to capture disability resulting from sagittal alignment.

Hospital-acquired conditions (HACs) have been the focus of recent initiatives by the Centers for Medicare and Medicaid Services in an effort to improve patient safety and outcomes. Spine surgery can be complex and may carry significant comorbidity burden, including so called "never events." The objective was to determine the rates of common HACs that occur within 30-days post-operatively for elective spine surgeries and compare them to other common surgical procedures. Patients: >18 y/o undergoing elective spine surgery were identified in the American College of Surgeons' NSQIP database from 2005 to 2013. Patients were stratified by whether they experienced >1 HAC, then compared to those undergoing other procedures including bariatric surgery, THA and TKA. Of the 90,551 spine surgery patients, 3021 (3.3%) developed at least one HAC. SSI was the most common (1.4%), followed by UTI (1.3%), and VTE (0.8%). Rates of HACs in spine surgery were significantly higher than other elective procedures including bariatric surgery (2.8%) and THA (2.8%) (both p < 0.001). Spine surgery and TKA patients had similar rates of HACs(3.3% vs 3.4%, p = 0.287), though spine patients experienced higher rates of SSI (1.4%vs0.8%, p < 0.001) and UTI (1.3%vs1.1%, p < 0.001) but lower rates of VTE (0.8%vs1.6%, p < 0.001). Spine surgery patients had lower rates of HACs overall (3.3%vs5.9%) when compared to cardiothoracic surgery patients (p < 0.001). When compared to other surgery types, spine procedures were associated with higher HACs than bariatric surgery patients and knee and hip arthroplasties overall but lower HAC rates than patients undergoing cardiothoracic surgery.

Study Design/UNASSIGNED:Retrospective review of single institution. Objective/UNASSIGNED:To assess the relationship between Patient-Reported Outcomes Measurement Information System (PROMIS) and Oswestry Disability Index (ODI) scores in thoracolumbar patients. Methods/UNASSIGNED:Included: Patients ≥18 years with a thoracolumbar spine condition (spinal stenosis, disc herniation, low back pain, disc degeneration, spondylolysis). Bivariate correlations assessed the linear relationships between ODI and PROMIS (Physical Function, Pain Intensity, and Pain Interference). Correlation cutoffs assessed patients with high and low correlation between ODI and PROMIS. Linear regression predicted the relationship of ODI to PROMIS. Results/UNASSIGNED:= 0.499) of the variance in Pain Intensity score. Conclusions/UNASSIGNED:There is a large amount of variability with PROMIS that cannot be accounted for with ODI. ODI questions regarding walking, social life, and lifting ability correlate strongly with PROMIS while sitting, standing, and sleeping do not. These results reinforce the utility of PROMIS as a valid assessment for low back disability, while indicating the need for further evaluation of the factors responsible for variation between PROMIS and ODI.

BACKGROUND:Ossification of the posterior longitudinal ligament (OPLL) is characterized by ectopic bone formation within the ligament and can elicit cervical spinal canal stenosis. Surgical treatment for OPLL is debated in the literature. This study examined nationwide data to estimate the prevalence of cervical OPLL (C-OPLL) and investigated trends in surgical treatment and outcomes. METHODS:A retrospective cross-sectional study was conducted of the National Inpatient Sample (NIS) database for patients with a diagnosis code for C-OPLL (ICD-9-CM 723.7) from 2005 to 2013. NIS supplied hospital- and yearadjusted weights allowed for accurate assessment of prevalence. Descriptive statistics assessed patient demographics, comorbidities, surgical factors, and complications. Trends were analyzed using chi-squared, ANOVA, and independent sample t-tests. RESULTS:A total of 4,601 C-OPLL discharges were identified (56.7 years, 43% female). The prevalence of C-OPLL has increased from 0.7/100,000 in 2005 to 2.1/100,000 in 2013. Among hospitalized C-OPLL patients, 89.1% underwent surgery, with 62.1% undergoing an anterior-only (A) approach, 21.5% posterior-only (P), and 16.4% combined (AP). Rates of anterior- and decompression-only surgeries have declined since 2005, from 67.5% to 44.4% and 21.6% to 14.8%, respectively (p < 0.001 for both). Corpectomy rates have dramatically increased, from 3.6% to 27.2% (p < 0.001). Overall complication rates have increased 2.5% since 2005 (p < 0.001) with higher rates of dysphagia (0.7%) and dural tears (5.6%) associated with A-only surgeries (p < 0.001 for both). The overall mortality rate was 0.8%, with P surgery associated with the highest rate, 1.6% (p = 0.002). CONCLUSIONS:The rate of hospitalization for C-OPLL has increased over the last decade as have morbidity rates for C-OPLL discharges. Anterior-only surgeries were associated with higher complication rates. Surgical rates have remained constantsince 2005, butrates of anterior-only and decompression-only procedures have decreased in favor of posterior-only and combined-approach surgeries.

INTRODUCTION/BACKGROUND:Obesity is associated with acceleration of musculoskeletal degenerative diseases and functional impairment secondary to spinal disorders. Bariatric surgery (BS) is an increasingly common treatment for severe obesity but can affect bone and mineral metabolism. The effect of BS on degenerative spinal disorders is yet to be fully described. The aim of our study was to analyze changes in bariatric patients' risk for spinal degenerative diseases and spinal surgery. METHODS:Retrospective analysis of the prospectively collected New York State Inpatient Database (NYSID) years (2004-2013) using patient linkage codes. The incidence of degenerative spinal diagnoses and spinal surgery was queried using International Classification of Diseases, Ninth Revision (ICD)-9 codes for morbidly obese patients (ICD-9 278.01) with and without a history of BS. The incidence of degenerative spinal diagnoses and spinal surgery was determined using χ tests for independence. Logistic testing controlled for age, sex, and comorbidity burden. RESULTS:A total of 18,176 patients were identified in the NYSID database with a history of BS and 146,252 patients were identified as morbidly obese without a history of BS. BS patients have a significantly higher rate of spinal diagnoses than morbidly obese patients without BS (19.3% vs. 8.1%, P<0.001). Bariatric patients were more likely to have spinal diagnoses and procedures than nonbariatric obese patients (P<0.001). This was mostly observed in lumbar spinal stenosis (5.0%), cervical disk herniation (3.3%), lumbar disk degeneration (3.4%), lumbar spondylolisthesis (2.9%), lumbar spondylosis (1.9%), and cervical spondylosis with myelopathy (2.0%). Spine procedure rates are higher for bariatric patients than nonbariatric overall (25.6% vs. 2.3, P<0.001) and for fusions and decompressions (P<0.001). When controlling for age, sex, and comorbidities (and diagnosis rate with regards to procedure rates), these results persist, with BS patients having a higher likelihood of spinal diagnoses and procedures. In addition, bariatric patients had a lower comorbidity burden than morbidly obese patients without a history of BS. CONCLUSIONS:Morbidly obese BS patients have a dramatically higher incidence of spinal diagnoses and procedures, relative to morbidly obese patients without BS. Further study is necessary to determine if there is a pathophysiological mechanism underlying this higher risk of spinal disease and intervention in bariatric patients, and the effect of BS on these rates following treatment. LEVEL OF EVIDENCE/METHODS:Level III.

BACKGROUND:Despite reports showing positive long-term functional outcomes following adult spinal deformity (ASD)-corrective surgery, it is unclear which factors affect the durability of these outcomes. OBJECTIVE:To assess durability of functional gains following ASD-corrective surgery; determine predictors for postoperative loss of functionality. METHODS:Surgical ASD patients > 18 yr with 3-yr Oswestry Disability Index (ODI) follow-up, and 1-yr postoperative (1Y) ODI scores reaching substantial clinical benefit (SCB) threshold (SCB < 31.3 points). Patients were grouped: those sustaining ODI at SCB threshold beyond 1Y (sustained functionality) and those not (functional decline). Kaplan-Meier survival analysis determined postoperative durability of functionality. Multivariate Cox regression assessed the relationship between patient/surgical factors and functional decline, accounting for age, sex, and levels fused. RESULTS:All 166 included patients showed baseline to 1Y functional improvement (mean ODI: 35.3 ± 16.5-13.6 ± 9.2, P < .001). Durability of satisfactory functional outcomes following the 1Y postoperative interval was 88.6% at 2-yr postoperative, and 71.1% at 3-yr postoperative (3Y). Those sustaining functionality after 1Y had lower baseline C2-S1 sagittal vertical axis (SVA) and T1 slope (both P < .05), and lower 1Y thoracic kyphosis (P = .035). From 1Y to 3Y, patients who sustained functionality showed smaller changes in alignment: pelvic incidence minus lumbar lordosis, SVA, T1 slope minus cervical lordosis, and C2-C7 SVA (all P < .05). Those sustaining functionality beyond 1Y were also younger, less frail at 1Y, and had lower rates of baseline osteoporosis, hypertension, and lung disease (all P < .05). Lung disease (Hazard Ratio:4.8 [1.4-16.4]), 1Y frailty (HR:1.4 [1.1-1.9]), and posterior approach (HR:2.6 [1.2-5.8]) were associated with more rapid decline. CONCLUSION/CONCLUSIONS:Seventy-one percent of ASD patients maintained satisfactory functional outcomes by 3Y. Of those who failed to sustain functionality, the largest functional decline occurred 3-yr postoperatively. Frailty, preoperative comorbidities, and surgical approach affected durability of functional gains following surgery.

PURPOSE/OBJECTIVE:To assess preliminary associations between fatty-infiltration (FI) of cervical spine extensor musculature, cervical sagittal balance, and clinical outcomes in cervical deformity (CD) patients. METHODS:Operative CD patients (C2-C7 Cobb > 10°, CL > 10°, cSVA > 4 cm, or CBVA > 25°) with pre-operative (BL) MRIs and 1-year (1Y) post-operative MRIs or CTs were assessed for fatty-infiltration of cervical extensor musculature, using dedicated imaging software at each C2-C7 intervertebral level and the apex of deformity (apex). FI was gauged as a ratio of fat-free-muscle-cross-sectional-area (FCSA) over total-muscle-CSA (TCSA), with lower ratio values indicating greater FI. BL-1Y associations between FI, sagittal alignment, and clinical outcomes were assessed using appropriate parametric and non-parametric tests. RESULTS:: 0.551, p = 0.014). CONCLUSIONS:Deformity correction and sagittal balance appear to influence the reestablishment of cervical muscle tone from C2-C7 and reduction of back pain for severely frail CD patients. This analysis helps to understand cervical extensor musculature's role amongst CD patients.

STUDY DESIGN/METHODS:Retrospective review. OBJECTIVE:The aim of this study was to develop a novel surgical invasiveness index for cervical deformity (CD) surgery that incorporates CD-specific parameters. SUMMARY OF BACKGROUND DATA/BACKGROUND:There has been a surgical invasiveness index for general spine surgery and adult spinal deformity, but a CD index has not been developed. METHODS:CD was defined as at least one of the following: C2-C7 Cobb > 10°, cervical lordosis (CL) > 10°, cervical sagittal vertical axis (cSVA) > 4 cm, chin brow vertical angle (CBVA) > 25°. Consensus from experienced spine and neurosurgeons selected weightings for each variable that went into the invasiveness index. Binary logistic regression predicted high operative time (>338 minutes), estimated blood loss (EBL) (>600 cc), or length of stay (LOS; > 5 days) based on the median values of operative time, EBL and LOS. Multivariable regression modeling was utilized to construct a final model incorporating the strongest combination of factors to predict operative time, LOS, and EBL. RESULTS:85 CD patients were included (61yrs, 66%F). The variables in the newly developed CD invasiveness index with their corresponding weightings were: history of prior cervical surgery (3), anterior cervical discectomy and fusion (ACDF) (2/level), corpectomy (4/level), levels fused (1/level), implants (1/level), posterior decompression (2/level), Smith-Peterson osteotomy (2/level), three column osteotomy (8/level), fusion to upper cervical spine (2), absolute change in T1 slope minus cervical lordosis (TS-CL), cSVA, T4-T12 thoracic kyphosis and sagittal vertical axis (SVA) from baseline to 1-year. The newly developed CD-specific invasiveness index strongly predicted long LOS (R = 0.310, p < 0.001), high EBL (R = 0.170, p = 0.011), and extended operative time (R = 0.207, p = 0.031). A second analysis used multivariable regression modeling to determine which combination of factors in the newly developed index were the strongest determinants of operative time, LOS, and EBL. The final predictive model included: number of corpectomies, levels fused, decompression, combined approach, and absolute changes in SVA, cSVA and TK. This model predicted EBL (R = 0.26), operative time (R = 0.12), and LOS (R = 0.13). CONCLUSIONS:Extended length of stay, operative time, and high blood loss were strongly predicted by the newly developed CD invasiveness index, incorporating surgical factors and radiographic parameters clinically relevant for patients undergoing cervical deformity corrective surgery. LEVELS OF EVIDENCE/METHODS:4.

BACKGROUND:Proximal junctional kyphosis (PJK) is a common radiographic complication of adult spinal deformity (ASD) corrective surgery. Although previous literature has reported a 5 to 61% incidence of PJK, these studies are limited by small sample sizes and short-term follow-up. OBJECTIVE:To assess the incidence of PJK utilizing a high-powered ASD database. METHODS:Retrospective review of a prospective multicenter ASD database. Operative ASD patients > 18 yr old from 2009 to 2017 were included. PJK was defined as ≥ 10° for the sagittal Cobb angle between the inferior upper instrumented vertebra (UIV) endplate and the superior endplate of the UIV + 2. Chi-square analysis and post hoc testing assessed annual and overall incidence of acute (6-wk follow-up [f/u]), progressive (increase in degree of PJK from 6 wk to 1 yr), and delayed (1-yr, 2-yr, and 3-yr f/u) PJK development. RESULTS:A total of 1005 patients were included (age: 59.3; 73.5% F; body mass index: 27.99). Overall PJK incidence was 69.4%. Overall incidence of acute PJK was 48.0%. Annual incidence of acute PJK has decreased from 53.7% in 2012 to 31.6% in 2017 (P = .038). Overall incidence of progressive PJK was 35.0%, with stable rates observed from 2009 to 2016 (P = .297). Overall incidence of 1-yr-delayed PJK was 9.3%. Annual incidence of 1-yr-delayed PJK has decreased from 9.2% in 2009 to 3.2% in 2016 (P < .001). Overall incidence of 2-yr-delayed PJK development was 4.3%. Annual incidence of 2-yr-delayed PJK has decreased from 7.3% in 2009 to 0.9% in 2015 (P < .05). Overall incidence of 3-yr-delayed PJK was 1.8%, with stable rates observed from 2009 to 2014 (P = .594). CONCLUSION/CONCLUSIONS:Although progressive PJK has remained a challenge for physicians over time, significantly lower incidences of acute and delayed PJK in recent years may indicate improving operative decision-making and management strategies.