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Studies have shown that site-specific bone density measurements had more predictive value for complications than standard whole-region measurements. Recently, MRI-based assessments of vertebral bone quality (VBQ) were introduced. However, there have been few studies that investigate the association between site-specific MRI bone assessment and osteoporosis-related complications in patients undergoing lumbar interbody fusion. In this work, we created a novel site-specific MRI-based assessment of the endplate bone quality (EBQ) and assessed its predictive value for severe cage subsidence following standalone lateral lumbar interbody fusion (SA-LLIF).To investigate the predictive value of a novel MRI-based bone assessment for severe cage subsidence after SA-LLIF.Retrospective cohort study.Patients who underwent SA-LLIF from 2008 to 2019 at a single, academic institution with available preoperative lumbar CT and T1-weighted MRIs.Association between EBQ and severe subsidence after SA-LLIF.We retrospectively reviewed the records of SA-LLIF patients treated between 2008 and 2019. EBQ was measured using preoperative non-contrast T1-weighted MRIs of the lumbar spine. EBQ was defined as the average value of signal intensity of both endplates divided by that of the cerebrospinal fluid space at the level of L3. Bivariate and multivariable analyses with generalized linear mixed models were performed and set binary severe subsidence as the outcome.Two hundred five levels in 89 patients were included. Fifty levels (24.4%) demonstrated severe subsidence. Bone mineral density measured by quantitative computed tomography was significantly lower in the subsidence group. Both VBQ and EBQ were significantly higher in the subsidence group. The EBQ plus Modic change (MC) model demonstrated that the effect of EBQ was independent of MC. In multivariate analyses adjusted with QCT-vBMD, EBQ showed a significant association with cage subsidence whereas VBQ only showed a marginal trend. The EBQ-based prediction model for severe subsidence showed better goodness of fit compared to the VBQ-based model.High EBQ was an independent factor for severe cage subsidence after SA-LLIF and the EBQ-based model showed better goodness of fit compared to VBQ- or MC-based models. EBQ assessment before SA-LLIF may provide insight into a patient's risk for severe subsidence.

Osteoporosis is a risk factor for instrumentation failure in spine surgery. Bone strength is commonly assessed by bone mineral density (BMD) as a surrogate marker. However, BMD represents only a portion of bone strength and does not capture the qualitative dimensions of bone. Recently, the magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score was introduced as a novel marker of bone quality. However, it is still unclear if the VBQ score correlates with in-vivo bone microstructure.The aims of the study were (1) to demonstrate differences in MRI-based (VBQ) and in-vivo (microcomputed tomography; μCT) bone quality between osteopenic/osteoporotic and normal bone, (2) to show the correlation between VBQ, bone microstructure and volumetric BMD (vBMD), and (3) to determine the predictive value of the VBQ score for the prevalence of osteopenia/osteoporosis.Retrospective cross-sectional study.267 patients who underwent posterior lumbar fusion surgery from 2014 to 2021 at a single academic institution. Bone biopsies were harvested intraoperatively in 118 patients.VBMD, VBQ score, and bone microstructure parameters derived from μCT.Quantitative computed tomography (QCT) measurements were performed at the lumbar spine and the L1/L2 average was used to categorize patients with a vBMD ≤120mg/cm267 patients (55.8% female, age 63.3 years, BMI 29.7 kg/mThis study demonstrated for the first time that the VBQ score is associated with trabecular microstructure determined by μCT. The bone microstructure and VBQ score were significantly different in patients with impaired vBMD. However, the ability to predict osteopenia/osteoporosis with the VBQ score was moderate. The VBQ score appears to reflect additional bone quality characteristics and might have a complementary role to vBMD. This enhances our understanding of the biological background of the radiographic VBQ score and might be a take-off point to evaluate the clinical utility of it as non-invasive screening tool for bone quality.

STUDY DESIGN Retrospective descriptive study. OBJECTIVE To create topographical maps of occipital bone thickness and venous sinus (VS) presence to assess the risks of screw insertion in four commercially available occipital plates. SUMMARY OF BACKGROUND DATA Craniocervical junction instability and deformity are serious pathological conditions that require posterior fixation of the occipital bone to the cervical vertebrae. Insertion of occipital bone screws requires evaluation of both occipital bone thickness for effective internal fixation and intracranial venous sinus presence for vascular injury prevention. Despite the surgical risks, there is a paucity of research on safe screw placement. METHODS We created a matrix of 231 standardized measurement points to analyze the occipital bone thickness and venous sinus presence in cervical spine CT angiograms. These measurements were used to create topographical maps of occipital bone thickness and likelihood of venous sinus presence, which we then compared to the screw hole configurations of four occipital plates. RESULTS 100 patients were assessed. Maximum occipital bone thickness of 13.9 ± 3.3 mm was midline in the occipital bone, 45 mm from the foramen magnum, around the external occipital protuberance (EOP). Regions with thicknesses >8 mm were 2 cm lateral to the EOP at the level of the superior nuchal line and 2.5 cm inferior to the EOP. The area with the highest VS presence rate was around the EOP and the superior nuchal line. The right transverse VS was more prominent in both sexes. CONCLUSION There is a limited area of the occipital bone with thicknesses for enough screw purchase. Previous studies have shown 8 mm as the minimum screw length to reduce the risk of implant failure. In our analysis, only "T"-shaped plates had configurations with thicknesses >8 mm for each screw hole. For every screw hole in the analyzed occipital plates, there was a possibility of venous sinus presence ranging from 8-33%.Level of Evidence: 5.

Retrospective cohort analysis.To elucidate trends in the utilization of intraoperative neuromonitoring (IONM) during elective anterior cervical decompression and fusion (ACDF) procedures in New York State using the Statewide Planning and Research Cooperative System (SPARCS) and to determine if utilization of IONM resulted in a reduction in postoperative neurologic deficits.IONM has been available to spinal surgeons for several decades. It has become increasingly prevalent in all facets of spinal surgery including elective ACDF procedures. The utility of IONM for preventing neurologic deficit in elective spine procedures has recently been called into question.The SPARCS database was accessed to perform a retrospective cohort study comparing monitored versus unmonitored ACDF procedures between 2007 to 2018 as defined by International Classification of Disease-9 and 10 Procedural Coding System (ICD-9 PCS, ICD-10 PCS) codes. Patient demographics, medical history, surgical intervention, pertinent in-hospital events, and urban versus rural medical center (as defined by the US Office of Management and Budget) were recorded. Propensity-score-matched (PSM) comparisons were used to identify factors related to the utilization of IONM and risk factors for neurologic deficits following elective ACDF.A total of 70,838 (15,092 monitored [21.3%] and 55,746 [78.7%] unmonitored) patients' data were extracted. The utilization of IONM since 2007 has increased in a linear fashion from 0.9% of cases in 2007 to 36.7% by 2018. Overall, baseline characteristics of patients who were monitored during cases differed significantly from unmonitored patients in age, race/ethnicity, insurance type, presence of myelopathy or radiculopathy, and Charlson Comorbidity Index (CCI); however, only race/ethnicity was statistically significant when analyzed using PSM. When comparing urban and rural medical centers, there is a significant lag in adoption of the technology with no monitored cases in rural centers until 2012 with significant fluctuations in utilization compared to steadily increasing utilization among urban centers. During 2017-2018 reporting of neurologic deficit after surgery resembled literature-established norms. Pooled analysis of these years revealed that incidence of neurological complication occurred more frequently in monitored cases than unmonitored (3.0% vs. 1.4%, P0.001).The utility of IONM for elective ACDF remains uncertain; however, it continues to gain popularity for routine cases. For medical centers that lack similar resources to centers in more densely populated regions of New York State, reliable access to this technology is not a certainty. In our analysis of intraoperative neurological complications, it appears that IONM is not protective against neurologic injury.

Study design Retrospective observational study. Objectives To investigate the spinal cord safety margins for C2 instrumentation. Summary of background data Intraoperative spinal cord injury during C2 spine surgery is a rare, but potentially life-threatening complication. Pre-operative planning for C2 instrumentation mainly focuses on C2 pedicle bony dimensions on CT and the vertebral artery location and few studies have evaluated C2 spinal cord safety margins. Methods We measured two distances in C2 bilaterally: 1) C2 pedicle to dura distance (P-D), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and the dural sac, 2) C2 pedicle to spinal cord (P-SC), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and spinal cord. We defined the distances above 4 mm as safe for instrumentation. Result A total of 146 patients (mean age 71.2, 50.7% female) were included. The average distances were 5.5 mm for C2 left P-D, 5.9 mm for C2 right P-D, 10.1 mm for C2 left P-SC and 10.6 mm for C2 right P-SC. Twenty eight (21.4%) patients had C2 P-D distances under 4 mm and out of those 2 (7%) patients had distances under 2 mm. There were more female patients with C2 P-D distances under 4 mm compared to males. No patient had C2 P-SC distances under 4 mm. Conclusion We demonstrated that around 20% of patients had C2 P-D distance below 4 mm, but no patient had C2 P-SC distance less than 4 mm. Since a lateral misplacement can lead to a potentially fatal vertebral artery injury, medial screw trajectory is recommended for C2 pedicle instrumentation with consideration of these safety margins.Level of Evidence: 3.

Background The preoperative assessment of C2 morphology is important for safe instrumentation. Sclerotic changes are often seen in C2 pedicles. Evaluating the diameter measurements solely might not accurately assess the safety of screw insertion. We have proposed a novel grading system of the C2 pedicle that includes sclerosis and evaluated the predictive value of this grading system with the surgeon's safety evaluation. Methods We reviewed and measured the dimensional values in 220 cervical computed tomography angiograms. Additionally, we used a grading system that divides the findings into 5 grades according to the width measurement and degree of sclerosis in the C2 pedicle. Two spine surgeons independently classified the pedicles as follows: safe (minimal risk of pedicle violation), caution needed (caution to minimize pedicle violation), or dangerous (a high risk of pedicle violation). Finally, we compared the measurements and the surgeons' safety assessments. Results A total of 411 pedicles of 203 patients (mean age, 69.5 years; 49.5% women) were included. Of the 411 C2 pedicles, 170 were classified as high risk by ≥1 surgeon. Between the dimensional measurements and grading system, the sclerotic grade showed the best predictive value. Conclusions We have introduced a novel tool to evaluate the safety of C2 pedicle screw placement. Our results suggest that our pedicle width–sclerosis grading system is reproducible and predicts the surgeon's assessment of safe screw placement better than C2 pedicle diametrical measurements alone.

The concept of sagittal spinal malalignment is well established in spinal surgery. However, the effect of musculature on its development has not been fully considered and the position of the pelvis is mostly seen as compensatory and not necessarily a possible cause of sagittal imbalance.This study aimed to investigate the influence of the posterior paraspinal muscles (PPM, erector spinae, and multifidus) and the psoas muscle on spinopelvic and spinal alignment.Retrospective cross-sectional study.Patients undergoing posterior lumbar fusion between 2014 and 2021 for degenerative conditions at a tertiary care center, with preoperative lumbar magnetic resonance imaging (MRI) within 12 months prior the surgery and a preoperative whole spine radiograph were included.PPM and psoas muscle measurements including the cross-sectional area (CSA), the functional cross-sectional area (fCSA), the amount of intramuscular fat (FAT), and the percentage of fat infiltration (FI). Spinopelvic measurements including lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), and sagittal vertical axis (SVA).A T2-weighted MRI-based quantitative assessment of the CSA, the fCSA and the amount FAT was conducted, and FI was further calculated. The regions of interest included the psoas muscle and the PPM on both sides at the L4 level that were summarized and normalized by the patient's height (cmA total of 150 patients (53.3% female) were included in the final analysis with a median age of 65.6 years and a median BMI of 28.2 kg/mThis study demonstrated the potential role of posterior paraspinal muscles and psoas muscle on pelvic retroversion and elucidated the relation to sagittal spinal malalignment. Although we cannot establish causality, we propose that increasing FI

Study design Longitudinal cohort. Objective The aims of this study were to measure concordance between patients' and surgeons' preoperative expectations of lumbar surgery, and determine which member of the dyad more closely predicted fulfillment of expectations, defined as patient-reported status postoperatively. Summary of background data Concordant patient-surgeon expectations reflect effective communication and should foster better outcomes. Methods Preoperatively patients and surgeons completed identical surveys measuring expectations for improvement in symptoms and physical/psychosocial function. Responses ranged from "complete improvement" to "do not have this expectation"; scores for each survey ranged from 0 to 100 (greatest expectations). Concordance between pairs of patient-surgeon scores was measured with the intraclass correlation coefficient (ICC). Postoperatively, fulfillment of expectations was measured from patient-reported amount of improvement received and was calculated as the proportion of patient-reported postoperative score relative to patient-reported preoperative score, and surgeon-reported preoperative score (range 0 [no expectations fulfilled] to >1.2 [expectations surpassed]). Clinical measures included patient-reported spine-related disability. Results For 402 patient-surgeon pairs, mean survey scores were 73 ± 19 (patients) and 57 ± 16 (surgeons); 84% of patients had higher scores than surgeons, mainly due to expecting complete improvement, whereas surgeons expected a lot/moderate/little improvement. The ICC for the entire sample was .31 (fair agreement); for subgroups, the greatest difference in ICC was for patients with more spine-related disability (ICC = .10, 95% confidence interval [CI]:0.00-0.23) versus less disability (ICC = .46, 95% CI: 0.34-0.56). 96% of patients were contacted ≥2.0 years postoperatively. Proportions of expectations fulfilled were 0.79 (0-3.00) (patients) and 1.01 (0-2.29) (surgeons). Thus patients were less likely to anticipate subsequent postoperative status (odds ratio [OR] 0.34, 95% CI 0.25-0.45) versus surgeons who were more likely to anticipate patient-reported postoperative status (OR 2.98, 95% CI: 2.22-4.00). Conclusion Concordance between patients' and surgeons' expectations was fair; due mostly to patients expecting complete improvement whereas surgeons expected a lot/moderate/little improvement. Compared to patients' expectations, surgeons' expectations more closely coincided with patient-reported fulfillment of expectations 2 years postoperatively.Level of Evidence: 1.

The aims of this study were to determine the time trend of demographics, complications, and outcomes for patients undergoing posterior lumbar interbody fusion/transforaminal lumbar interbody fusion (PLIF/TLIF) or anterior lumbar interbody fusion/lateral lumbar interbody fusion (ALIF/LLIF) and to compare the differences in the time trends between both procedures.The American College of Surgeons National Surgical Quality Improvement Program database was queried for patients undergoing PLIF/TLIF and ALIF/LLIF procedures. Outcomes were analyzed for differences between 2 time periods in the PLIF/TLIF and ALIF/LLIF cohorts separately (2009-2013 and 2015-2019). Longitudinal time trends of the 2 procedures were determined by difference-in-differences (DID) analysis. Statistical significance was defined as P 0.05.For both approaches, there was an increase in age and American Society of Anesthesiologists class over time, accompanied by a significant decrease in blood transfusions and morbidity. The DID analysis showed a greater change in age (DID:-1.8%; P0.001), and more patients were rated American Society of Anesthesiologists class 3 (DID: -2.4%; P = 0.033) in the ALIF/LLIF cohort than in the PLIF/TLIF cohort. Length of stay declined significantly over time in both cohorts, with a greater reduction observed for patients who underwent ALIF/LLIF than for patients who underwent PLIF/TLIF (DID: 0.2%; P = 0.014). There were no changes in readmission rates over time in either cohort (PLIF/TLIF DID: 0.6%; P = 0.080; ALIF/LLIF DID: -0.2%; P = 0.696).Time trends for PLIF/TLIF and ALIF/LIIF showed a significant increase in the number of older patients with complex medical status undergoing surgery. Despite these trends, there were decreases in overall postoperative morbidity, incidence of blood transfusion, and length of stay, without increasing readmission. These results suggest general improvement in surgical and perioperative management of lumbar fusion over time with greater gains found in ALIF/LLIF-specific care than in PLIF/TLIF.

The effect of psoas and paraspinal muscle parameters on cage subsidence after minimally invasive techniques, such as standalone lateral lumbar interbody fusion (SA-LLIF), is unknown.This study aimed to determine whether the functional cross-sectional area (FCSA) of psoas and lumbar spine extensor muscles (multifidus and erector spinae), and psoas FCSA normalized to the vertebral body area (FCSA/VBA) differ among levels with severe cage subsidence after SA-LLIF when compared to levels without severe cage subsidence.Retrospective single center cohort study.Patients who underwent SA-LLIF between 2008 and 2020 for degenerative conditions using exclusively polyetheretherketone (PEEK) cages, had a lumbar magnetic resonance imaging (MRI) scan within 12 months, a lumbar computed tomography (CT) scan within 6 months prior to surgery, and a postoperative clinical and radiographic follow-up at a minimum of 6 months were included.Severe cage subsidence.MRI measurements included psoas and combined multifidus and erector spinae (paraspinal) FCSA and FCSA/VBA at the L3-L5 pedicles. Following manual segmentation of muscles on axial T2-weighted images using ITK-SNAP (version 3.8.0), the FCSA was calculated using a custom written program on Matlab (version R2019a, The MathWorks, Inc.) that used an automated pixel intensity threshold method to differentiate between fat and muscle. Mean volumetric bone mineral density (vBMD) at L1/2 was measured by quantitative CT. The primary endpoint was severe cage subsidence per level according to the classification by Marchi et al. Multivariable logistic regression analysis was performed using generalized linear mixed models. All analyses were stratified by biological sex.95 patients (45.3% female) with a total of 188 operated levels were included in the analysis. The patient population was 92.6% Caucasian with a median age at surgery of 65 years. Overall subsidence (Grades 0-III) was 49.5% (53/107 levels) in men versus 58.0% (47/81 levels) in women (p=.302), and severe subsidence (Grades II-III) was 22.4% (24/107 levels) in men versus 25.9% (21/81 levels) in women (p=.608). In men, median psoas FCSA and psoas FCSA/VBA at L3 and L4 were significantly greater in the severe subsidence group when compared to the non-severe subsidence group. No such difference was observed in women. Paraspinal muscle parameters did not differ significantly between non-severe and severe subsidence groups for both sexes. In the multivariable logistic regression analysis with adjustments for vBMD and cage length, psoas FCSA at L3 (OR 1.002; p=.020) and psoas FCSA/VBA at L3 (OR 8.655; p=.029) and L4 (OR 4.273; p=.043) were found to be independent risk factors for severe cage subsidence in men.Our study demonstrated that greater psoas FCSA at L3 and psoas FCSA/VBA at L3 and L4 were independent risk factors for severe cage subsidence in men after SA-LLIF with PEEK cages. The higher compressive forces the psoas exerts on lumbar segments as a potential stabilizer might explain these findings. Additional pedicle screw fixation might be warranted in these patients to avoid severe cage subsidence.

Study design Retrospective case series. Objective The aim of this study was to investigate the association of Modic type endplate changes with the risk of severe subsidence after standalone lateral lumbar interbody fusion (SA-LLIF). Summary of background data It has been reported that certain endplate radiolographic features are associated with higher regional bone mineral density (BMD) in the adjacent vertebrae in the lumbar spine. It remains unclear whether these changes have protective effects against osteoporotic complications such as cage subsidence after lumbar surgery. Methods We reviewed patients undergoing SA-LLIF from 2007 to 2016 with a follow-up >6 months. Cage subsidence was assessed utilizing the grading system by Marchi et al. As potential contributing factors for cage subsidence, we measured the endplate volumetric BMD (EP-vBMD) and the standard trabecular volumetric BMD measurement in the vertebral body. Modic changes (MC) on magnetic resonance imaging were measured as a qualitative factor for endplate condition. Univariate analysis and multivariate logistic regression analyses with a generalized mixed model were conducted. Results Two hundred six levels in 97 patients were included in the final analysis. Mean age (± SD) was 66.7 ± 10.7. Sisty-sdpercent of the patients were female. Severe subsidence was observed in 66 levels (32.0%). After adjusting for age, bone morphogenetic protein (BMP) use, and number of levels fused, the presence of MC type 2 was significantly associated with lower risk of severe subsidence (OR = 0.28 [0.09-0.88], P = 0.029). Whereas, EP-vBMD did not demonstrate a statistical significance (p = 0.600). Conclusion The presence of a Modic type 2 change was significantly associated with lower odds of severe subsidence after SA-LLIF. Nonetheless, this significant association was independent from regional EP-vBMD values. This finding suggests that microstructural and/or material property changes associated with Modic type 2 changes might have a protective effect in this patient population. Level of evidence 4.

Background context Clinically, the association between bone mineral density (BMD) and surgical instrumentation efficacy is well recognized. Although several studies have quantified the BMD of the human lumbar spine, comprehensive BMD data for the cervical spine is limited. The few available studies included young and healthy patient samples, which may not represent the typical cervical fusion patient. Currently no large scale study provides detailed BMD information of the cervical and first thoracic vertebrae in patients undergoing anterior cervical spine surgery. Purpose The objective of this study was to determine possible trabecular BMD variations throughout the cervical spine and first thoracic vertebra in patients undergoing anterior cervical discectomy and fusion (ACDF) and to assess the correlation between BMDs of the spinal levels C1-T1. Study Design/Setting This is a retrospective case series. Patient Sample Patients undergoing ACDF from 2015 to 2018 at a single, academic institution with available preoperative CT imaging were included in this study. Outcome Measures The outcome measure was bone mineral density measured by QCT. Methods Patients that underwent ACDF from 2015 to 2018 at a single, academic institution were included in this study. Subjects with previous cervical instrumentation or missing/incomplete preoperative cervical spine CT imaging were excluded. Asynchronous quantitative computed tomography (QCT) measurements of the lateral masses of C1 and the C2-T1 vertebral bodies were performed. For this purpose, an elliptical region of interest (ROI) that consisted exclusively of trabecular bone was selected. Any apparent sclerotic levels that might affect trabecular QCT measurements were excluded from the final analysis. Interobserver reliability of measurements was assessed by calculating the interclass correlation coefficients (ICC). Pairwise comparison of BMD was performed and correlations between the various cervical levels were evaluated. The statistical significance level was set at p Results In all, 194 patients (men, 62.9%) met inclusion criteria. The patient population was 91.2% Caucasian with a mean age of 55.9 years and mean BMI of 28.2 kg/m2. The ICC of cervical QCT measurements was excellent (ICC 0.92). The trabecular BMD was highest in the mid-cervical spine (C4) and decreased in the caudal direction (C1 average = 253.3 mg/cm3, C2 = 276.6 mg/cm3, C3 = 272.2 mg/cm3, C4 = 283.5 mg/cm3, C5 = 265.1 mg/cm3, C6 = 235.3 mg/cm3, C7 = 216.8 mg/cm3, T1 = 184.4 mg/cm3). The BMD of C7 and T1 was significantly lower than those of all other levels. Nonetheless, significant correlations in BMD among all measured levels were observed, with a Pearson's correlation coefficient ranging from 0.507 to 0.885. Conclusions To the authors’ knowledge this is the largest study assessing trabecular BMD of the entire cervical spine and first thoracic vertebra by QCT. The patient sample consisted of patients undergoing ACDF, which adds to the clinical relevance of the findings. Knowledge of BMD variation in the cervical spine might be useful to surgeons utilizing anterior cervical spine plate and screw systems. Due to the significant variation in cervical BMD, procedures involving instrumentation at lower density caudal levels might potentially benefit from a modification in instrumentation or surgical technique to achieve results similar to more cephalad levels.

Objective There have been some reports on the association between spinal balance parameters and regional bone mineral density (BMD), but the results are controversial. The purpose of this study is to evaluate the relationship between spinopelvic parameters and regional volumetric BMDs (vBMDs) measured by quantitative computed tomography (QCT) in the lumbosacral region of patients undergoing lumbar fusion surgery. Methods The data of consecutive patients undergoing posterior lumbar spinal fusion with preoperative computed tomography was reviewed. QCT measurements were conducted in L1–S1 vertebral trabecular bone. The associations between spinopelvic sagittal parameters and vBMDs were evaluated. Multivariate analyses adjusted with age, gender, race, and body mass index were conducted with vBMD as the response variable. Results A total of 144 patients were included in the final analyses. Mean age (± standard deviation) was 65.4 ± 11.8 years. Mean vBMD in L1 (± standard deviation) was 118.3 ± 37.4 mg/cm3. After adjusting by cofactors, lumbar lordosis was negatively associated with vBMDs in all levels from L1 to L5 (% regression coefficients and adjusted R2 values: L1, –0.438, 0.268; L2, –0.556, 0.296; L3, –0.608, 0.362; L4, –0.554, 0.228; L5, –0.424, 0.194), but not in S1. Sacral slope was negatively associated with vBMD only at L4 (% coefficient, –0.588; R2, 0.208). Other parameters were not significantly associated with vBMDs at any levels. Conclusions Higher lumbar lordosis was associated with lower vBMDs in all lumbar spine levels. Our results suggest that BMD is affected not only by metabolic factors but also by the mechanical environment. Further longitudinal studies are needed to elucidate this effect of vBMD on clinical outcomes.

Background Lateral lumbar interbody fusion can be performed without supplemental posterior instrumentation. Previous reports have shown favorable results with stand-alone lateral lumbar interbody fusion (SA-LLIF); however, a reoperation rate of up to 26% has been reported. It remains unclear what perioperative factors are associated with early failure after SA-LLIF. The objective of this study is to determine perioperative factors that increase the risk of early revisions after SA-LLIF. Methods Data of consecutive patients with SA-LLIF were reviewed. All revisions or recommendations for revision surgery within 12 months after the LLIF procedure were documented. As potential contributors, operative levels, preoperative clinical diagnosis, number of fusion levels, and the average L1/L2 quantitative computed tomography–volumetric bone mineral density value were obtained along with other demographic factors. Cage subsidence (grade 0–III as per Marchi et al.), was also evaluated in patients who had radiographs/computed tomography between 6 and 12 months postoperatively (n = 122). Logistic regression analyses were conducted. Results Of 133 eligible patients, 21 (15.8%) underwent revision surgery and 4 (3.0%) were recommended for revision surgery within 1 year primarily because of neurologic symptoms or pain (68%). Baseline demographics showed no significant difference between the revision and the nonrevision group. The average number of levels fused was 2.12 (revision group) and 2.14 (nonrevision group) (P = 0.55). Significantly more patients in the revision group had the diagnosis of foraminal stenosis (64.0% vs. 39.8%; P = 0.04). Conclusions Patients with foraminal stenosis were more likely to have early revision surgery after SA-LLIF primarily because of neurologic symptoms/pain. This information can assist in preoperative discussions and management of patient expectations.

BACKGROUND CONTEXT It has been reported that degenerative disc disease (DDD) is associated with higher spinal bone mineral density (BMD) based on previous studies that used dual X-ray absorptiometry (DXA). However, DDD is often associated with proliferative bone changes and can lead to an overestimation of BMD measured with DXA. Trabecular volumetric BMD (vBMD) in the vertebral body measured with quantitative computed tomography (QCT) is less affected by those changes and can be a favorable alternative to DXA for patients with degenerative spinal changes. PURPOSE The purpose of this study is to investigate the effect of DDD on regional trabecular vBMDs in the vertebral body measured by QCT. STUDY DESIGN/SETTING Cross-sectional observational study at a single academic institution. PATIENTS SAMPLE Consecutive patients undergoing posterior lumbar spinal fusion between 2014 and 2017 who had a routine preoperative CT scan and magnetic resonance imaging (MRI) within a 90-day interval. OUTCOME MEASURES Regional trabecular vBMDs in the vertebral body by QCT. METHODS QCT measurements were conducted in L1–S1 vertebral trabecular bone. Any apparent sclerotic lesions that might affect vBMD values were excluded from the region of interest. The vBMDs of each level were defined as the average vBMD of the upper and lower vertebrae. To evaluate DDD, Pfirrmann grade, Modic grade, total end plate score, and vacuum phenomenon were documented. Univariate regression analysis and multivariate analyses with a linear mixed model adjusted with individual variability of segmental vBMDs were conducted with vBMD as the response variable. RESULTS Of 143 patients and 715 disc levels, 125 patients and 596 discs met our inclusion criteria. Mean vBMD (±standard deviation [SD]) of all levels was 119.0±39.6 mg/cm3. After adjusting for all covariates, Pfirrmann grade was not an independent contributor to vBMD, but the presence of any Modic change (type 1, β=6.8, p≤.001; type 2, β=6.7, p CONCLUSIONS Our results showed that the presence of certain end plate lesions (Modic changes and high TEPS) on MRI was significantly associated with increased regional QCT-vBMDs in the vertebral body, but no significant association was observed with disc nucleus pathology, unless it was associated with a vacuum phenomenon. When end plate lesions with Modic changes and high TEPS are present at the measuring level, care must be taken to interpret vBMD values, which might be overestimations even if the trabecular area appears normal.

To compare outcomes of three-dimensional-printed porous titanium (Ti) versus polyetheretherketone (PEEK) cage implantation for stand-alone lateral lumbar interbody fusion (SA-LLIF) in treatment of symptomatic adjacent segment degeneration.Between October 2016 and July 2020, 44 patients (59 levels) underwent stand-alone lateral lumbar interbody fusion with Ti or PEEK cages. The primary outcome was cage subsidence. Secondary outcomes included revision and/or recommendations for revision surgery, back and/or leg pain severity, changes in disc and/or foraminal height, and global and/or segmental lumbar lordosis.The study included 44 patients (21 females) with a mean age at surgery of 61.8 ± 11.5 years, mean radiological follow-up of 12.5 ± 8.2 months, and mean clinical follow-up of 11.0 ± 7.1 months. Overall subsidence rate was significantly less in the Ti versus PEEK group (20% vs. 58.8%, P = 0.004). Revision was recommended to none of the patients in the Ti group and 3 patients in the PEEK group (P = 0.239). Patients in the Ti group showed significantly better improvement in back pain numeric rating scale score (P = 0.001). Disc height (P0.001) and foraminal height restoration (P = 0.011) were statistically significant in the Ti group, whereas only disc height restoration was significant in the PEEK group (P = 0.003).In patients undergoing stand-alone lateral lumbar interbody fusion to treat adjacent segment degeneration, Ti cages had a significantly lower overall subsidence rate compared with PEEK cages. Furthermore, Ti cages resulted in fewer recommendations for revision surgery. Whether greater pain reduction in the Ti group is associated with earlier or higher fusion rates needs to be further elucidated.

The importance of bone status assessment in spine surgery is well recognized. The current gold standard for assessing bone mineral density is dual-energy X-ray absorptiometry (DEXA). However, DEXA has been shown to overestimate BMD in patients with spinal degenerative disease and obesity. Consequently, alternative radiographic measurements using data routinely gathered during preoperative evaluation have been explored for the evaluation of bone quality and fracture risk. Opportunistic quantitative computed tomography (QCT) and more recently, the MRI-based vertebral bone quality (VBQ) score, have both been shown to correlate with DEXA T-scores and predict osteoporotic fractures. However, to date the direct association between VBQ and QCT has not been studied.The objective of this study was to evaluate the correlation between VBQ and spine QCT BMD measurements and assess whether the recently described novel VBQ score can predict the presence of osteopenia/osteoporosis diagnosed with QCT.Cross-sectional study using retrospectively collected data.Patients undergoing lumbar fusion from 2014-2019 at a single, academic institution with available preoperative lumbar CT and T1-weighted MRIs were included.Correlation of the VBQ score with BMD measured by QCT, and association between VBQ score and presence of osteopenia/osteoporosis.Asynchronous QCT measurements were performed. The average L1-L2 BMD was calculated and patients were categorized as either normal BMD (120 mg/cmA total of 198 patients (53% female) were included. The mean age was 62 years and the mean BMI was 28.2 kg/mWe found that the VBQ score showed moderate diagnostic ability to differentiate patients with normal BMD versus osteopenic/osteoporotic BMD based on QCT. VBQ may be an interesting adjunct to clinically performed bone density measurements in the future.

Anterior cervical discectomy and fusion (ACDF) is a safe and effective procedure but has approach-related complications like postoperative dysphagia and dysphonia (PDD). Patient-reported outcome measures including the Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) have been used for the assessment of PDD. Various factors have been described that affect ACDF outcomes, and our aim was to investigate the effect of workers' compensation (WC) status.We included patients who underwent ACDF from 2015 to 2018 stratified according to insurance status: WC/non-WC. PDDs were assessed using the HSS-DDI score. We conducted logistic regression analyses. Statistical significance was set at P0.05.We included 287 patients, 44 (15.33%) WC and 243 (84.67%) non-WC. A statistical comparison revealed a clinically relevant difference in the HSS-DDI total score and both subdomains (P = 0.015; dysphagia P = 0.021; dysphonia P = 0.002). Additional logistic regression analysis adjusting for preoperative Neck Disability Index scores resulted in no clinically relevant differences in the HSS-DDI total score and both subdomains (total score P = 0.420; dysphagia P = 0.531; dysphonia 0.315).WC status was associated with a worse HSS-DDI score but could not be shown to be an independent risk factor for PDD. The preoperative NDI score was a strong predictor for PDD with a clinically relevant difference in the HSS DDI score (P0.0001). Surgeon awareness of risk factors for PDD such as WC status, even if it could not be shown as independent, is important as it may influence surgical decision making and managing patient expectations.

STUDY DESIGN Retrospective database analysis. OBJECTIVE To identify preoperative risk factors for emergency department (ED) visit and unplanned hospital readmission after primary anterior cervical discectomy and fusion (ACDF) at 30 and 90 days. SUMMARY OF BACKGROUND DATA Limited data exist to identify factors associated with ED visit or readmission after primary ACDF within the first 3 months following surgery. METHODS Patients undergoing ACDF from 2005 to 2012 were identified in the Statewide Planning and Research Cooperative System database. Multivariable regression models were created based on patient-level and surgical characteristics to identify independent risk factors for hospital revisit. RESULTS Of 41,813 patients identified, 2514 (6.0%) returned to the ED within 30 days of discharge. Risk factors included age 1, length of stay (LOS) greater than 1 day (OR 1.23), and fusion of > 2 levels (OR 1.17). Four thousand six hundred nine (11.0%) patients returned to the ED within 90 days. Risk factors mirrored those at 30 days. Patients having private insurance or those discharged to rehab were less likely to present to the ED. One thousand three hundred ninety-four (3.3%) patients were readmitted by 30 days. Risk factors included male sex, Medicare, or Medicaid insurance (OR 1.71 and 1.79 respectively), Charlson comorbidity index > 1, discharge to a skilled nursing facility (OR 2.90), infectious/pathologic (OR 3.296), or traumatic (OR 1.409) surgical indication, LOS > 1 day (OR 1.66), or in-hospital complication. 2223 (5.3%) patients were readmitted by 90 days. Risk factors mirrored those at 30 days. No differences in readmission were seen based on race or number of levels fused. Patients aged 18 to 34 were less likely to be readmitted versus patients older than 35. CONCLUSION Insurance status, comorbidities, and LOS consistently predicted an unplanned hospital visit at 30 and 90 days. Although nondegenerative surgical indications and in-hospital complications did not predict ED visits, these factors increased the risk for readmission. LEVEL OF EVIDENCE 3.

BACKGROUND CONTEXT Quantitative computed tomography (QCT) of the lumbar spine is used as an alternative to dual-energy X-ray absorptiometry in assessing bone mineral density (BMD). The average BMD of L1-L2 is the standard reportable metric used for diagnostic purposes according to current recommendations. The density of L1 and L2 has also been proposed as a reference value for the remaining lumbosacral vertebrae and is commonly used as a surrogate marker for overall bone health. Since regional BMD differences within the spine have been proposed, it is unclear if the L1-L2 average correlates with the remainder of the lumbosacral spine. PURPOSE The aim of this study was to determine possible BMD variations throughout the lumbosacral spine in patients undergoing lumbar fusion and to assess the correlation between the clinically used L1-L2 average and the remaining lumbosacral vertebral levels. STUDY DESIGN/SETTING This is a retrospective case series. PATIENT SAMPLE Patients undergoing posterior lumbar spinal fusion from 2014 to 2017 at a single, academic institution with available preoperative CT imaging were included in this study. OUTCOME MEASURES The outcome measure was BMD measured by QCT. METHODS Standard QCT measurements at the L1 and L2 vertebra and additional experimental measurements of L3, L4, L5, and S1 were performed. Subjects with missing preoperative lumbar spine CT imaging were excluded. The correlations between the L1-L2 average and the other vertebral bodies of the lumbosacral spine (L3, L4, L5, S1) were evaluated. RESULTS In total, 296 consecutive patients (55.4% female, mean age of 63.1 years) with available preoperative CT were included. The vertebral BMD values showed a gradual decrease from L1 to L3 and increase from L4 to S1 (L1=118.8 mg/cm3, L2=116.6 mg/cm3, L3=112.5 mg/cm3, L4=122.4 mg/cm3, L5=135.3 mg/cm3, S1=157.4 mg/cm3). There was strong correlation between the L1-L2 average and the average of the other lumbosacral vertebrae (L3-S1) with a Pearson's correlation coefficient (r=0.85). We also analyzed the correlation between the L1-L2 average and each individual lumbosacral vertebra. Similar relationships were observed (r value, 0.67–0.87), with the strongest correlation between the L1-L2 average and L3 (r=0.87). CONCLUSIONS Our data demonstrate regional BMD differences throughout the lumbosacral spine. Nevertheless, there is high correlation between the clinically used L1-L2 average and the BMD values in the other lumbosacral vertebrae. We, therefore, conclude the standard clinically used L1-L2 BMD average is a useful bone quantity measure of the entire lumbosacral spine in patients undergoing lumbar spinal fusion.

Background Context Sacral fractures are a rare but potentially devastating complication. Long-fusion constructs, including the sacrum, that do not extend to the pelvis may result in sacral fractures. Besides established risk factors including gender, age, and number of levels fused, body mass index (BMI), pelvic parameters, and bone mineral density (BMD) have also been proposed as potential risk factors for postoperative sacral fractures. The literature supporting this, however, is limited. Purpose The aim of the present study was to assess whether preoperative pelvic parameters, BMI, or BMD of patients with sacral fracture are different compared with age, gender, and fusion level-matched non-fracture controls. Study Design/Setting This is a case-control study. Patient Sample Patients undergoing posterior instrumented fusion at a single academic institution between 2002 and 2016 were included in the study. Outcome Measures The outcome measure was occurrence of a postoperative sacral fracture. Methods Patients with sacral fractures after posterior instrumented spinal fusion, including the sacrum, were retrospectively identified and matched 2:1 with non-fracture controls based on gender, age, and number of levels fused. Patients with concurrent spinopelvic fixation or missing preoperative computed tomography (CT) imaging were excluded. Preoperative sagittal balance was assessed using lateral radiographs. Quantitative computed tomography (QCT) assessment included standard measurements at L1/L2 and additional experimental measurements of the S1 body and sacral ala. Results Twenty-one patients with sacral fracture were matched to non-fracture controls. The majority of the patients with sacral fracture was female (76.2%) and of advanced age (mean 66.4 years). Fracture and control groups were well matched with respect to gender, age, and number of levels fused. Standard measurements at L1/L2 showed no significant difference in BMD between the fracture and the control groups (109.9 mg/cm3 vs. 116.4 mg/cm3, p=.414). Similarly, there was no significant BMD differences between the groups using the experimental measurements of the S1 body (183.6 mg/cm3 vs. 176.2 mg/cm3, p=.567) and the sacral ala (8.9 mg/cm3 vs. 4.8 mg/cm3, p=.616). Mean preoperative pelvic incidence-lumbar lordosis mismatch and pelvic tilt were not significantly different between the groups. Univariate conditional logistic regression analysis revealed that the odds of experiencing a sacral fracture was approximately six times higher for obese patients compared with normal or underweight patients. After controlling for BMI in multivariate conditional logistic regression models, BMD was still not significantly associated with the odds of experiencing sacral fractures. Conclusions To our knowledge, this is the first study to assess the association of preoperative BMD measured by QCT, pelvic parameters, and BMI with postoperative sacral fractures in a large patient cohort. Interestingly, our data do not show any difference in preoperative pelvic parameters and BMD between the groups. This is in line with previous reports that indicate only a few patients with sacral fracture after fusion surgery have clear evidence of osteoporosis. Bone mineral density as a measure of bone quantity, rather than bone quality, may not be as important in these fractures as previously thought. Obesity, however, was associated with higher odds of experiencing postoperative sacral fractures. The present study thereby challenges the widespread concept that obesity is a protective factor against fractures in the elderly. In summary, our results suggest that BMI and gender, more than pelvic parameters and BMD, are risk factors for postoperative sacral fractures.

BACKGROUND CONTEXT The thoracic spine is a common location for vertebral fractures as well as instrumentation failure after long spinal fusion procedures. The association between those complications and bone mineral density (BMD) are well recognized. Due to the overlying sternum and ribs in the thoracic spine, projectional BMD assessment tools such as dual energy x-ray absorptiometry (DXA) are limited to the lumbar spine. Quantitative computed tomography circumvents several shortcomings of DXA and allows for level-specific BMD measurements. Studies comprehensively quantifying BMD of the entire thoracic spine in patients undergoing spine surgery are limited. PURPOSE The objective of this study was: (1) to assess the reliability of thoracic QCT measurements, (2) to determine possible level-specific BMD variation throughout the thoracic spine and (3) to assess the correlation between BMDs of the T1-T12 spinal levels. STUDY DESIGN/SETTING Cross-sectional observation study. PATIENT SAMPLE Patients undergoing spine surgery from 2016–2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study. OUTCOME MEASURES The outcome measure was BMD measured by QCT. METHODS Patients undergoing spine surgery from 2016–2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study. Subjects with previous instrumentation at any thoracic level, concurrent vertebral fractures, a Cobb angle of more than 20 degrees, or incomplete thoracic spine CT imaging were excluded. Asynchronous quantitative computed tomography (QCT) measurements of T1-T12 were performed. To assess inter- and intra-observer reliability, a validation study was performed on 120 vertebrae in 10 randomly selected patients. The interclass correlation coefficient (ICC) was calculated. A pairwise comparison of BMD was conducted and correlations between each thoracic level were evaluated. The statistical significance level was set at p RESULTS 60 patients (men, 51.7%) met inclusion criteria. The study population was 90% Caucasian with a mean age of 62.2 years and a mean BMI of 30.2 kg/m2. The inter- and intra-observer reliability of the thoracic QCT measurements was excellent (ICC of 0.97 and 0.97, respectively). The trabecular BMD was highest in the upper thoracic spine and decreased in the caudal direction (T1 = 182.3 mg/cm3, T2 = 168.1 mg/cm3, T3 = 163.5 mg/cm3, T4 = 164.7 mg/cm3, T5 = 161.4 mg/cm3, T6 = 152.5 mg/cm3, T7 = 143.5 mg/cm3, T8 = 141.3 mg/cm3, T9 = 143.5 mg/cm3, T10 = 145.1 mg/cm3, T11 = 145.3 mg/cm3, T12 = 133.6 mg/cm3). The BMD of all thoracic levels cranial to T6 was statistically higher than the BMD of all levels caudal to T6 (p CONCLUSIONS There is significant regional BMD variation in the thoracic spine depending on spinal level. This BMD variation might contribute to several clinically relevant phenomena. First, vertebral fractures occur most commonly at the thoracolumbar junction including T12. In addition to mechanical reasons, these fractures might be partially attributed to thoracic BMD that is lowest at T12. Second, the optimal upper instrumented vertebra (UIV) for stopping long fusions to the sacrum and pelvis is controversial. The BMD of surgically relevant upper thoracic stopping points (T2-T4) was significantly higher than the BMD of lower thoracic stopping points (T10-T12). Besides stress concentration at the relatively mobile lower thoracic segments, the low BMD at these levels might contribute to previously suggested higher rates of junctional failures with short fusions.

BACKGROUND CONTEXT Low muscle volume, also called sarcopenia, is a common condition of aging with a prevalence between 1 and 29% in populations over the age of 50 years. Previous studies have demonstrated evidence that both osteoporosis and sarcopenia coexist, called osteosarcopenia, and these patients are at greater risk for falls, fractures and mortality. In osteoporotic post-menopausal female patients, the prevalence of sarcopenia is around 50%. Recent studies showed that sarcopenic subjects had a 4-fold higher risk of coexisting osteoporosis compared with nonsarcopenic individuals. However, a limited number of studies have been conducted in spine surgery patients. PURPOSE The aim of this study is to investigate the associations between the lean muscle volume (LMV) in paraspinal and proas muscle on MRI and quantitative computed tomography (QCT) volumetric bone mineral density (vBMD) in the lumbosacral region. STUDY DESIGN/SETTING A cross-sectional analysis of a prospectively maintained database at a single academic institution. PATIENT SAMPLE Patients undergoing posterior lumbar fusion surgery between 2014-2020. OUTCOME MEASURES Volumetric BMD measured by QCT in the lumbar spine and sacral ala. METHODS We reviewed an institutional database of posterior lumbar fusion patients. Patients who had ongoing antiosteoporotic therapy with bisphosphonate, denosumab or teriparatide were excluded. Muscle measurements were conducted utilizing a free software program (ITK-SNAP version 3.8) setting regions of interest (ROI) in the bilateral psoas and paraspinal (erector spinae and multifundus) muscles on preoperative T2-weighted axial MR images at the mid-L3 level. The area of fat-free muscle (LMV: lean muscle volume) was calculated using a custom written program on Matlab™ (MATLAB version 2019a, The MathWorks, Inc, Natick, MA, USA). QCT measurements were performed on preoperative CT scans using the Mindways QCT Pro Software (Mindways Software, Inc., Austin, TX, USA). QCT-vBMDs in the standard L1-L2 and bilateral sacral ala were analyzed. Pearson's correlation and linear regression analyses adjusting with age and BMI were performed. Since muscle volume is strongly affected by biological sex, we stratified by sex for all analyses. Statistical significance was set RESULTS Out of 144 patients, 30 patients were excluded due to QCT incompatible CTs or poor quality MRIs for muscle volume measurements. An additional 9 patients were excluded due to ongoing anti-osteoporotic drug therapy. A total of 105 patients (50 male and 55 female) were included in the final analysis. In female patients, there were statistically significant mild to moderate positive correlations between L1-L2 vBMD and LMV in paraspinal and psoas muscles, as well as sacral ala vBMD and paraspinal LMV, whereas there was no significant correlation in male patients. After the adjustment with age and BMI, high paraspinal LMV was an independent factor for high sacral ala vBMD (β=0.04 (95%CI: 0.00-0.14), p=0.040) and high psoas LMV was significantly associated with high L1-L2 vBMD (β=0.04 (95%CI: 0.01-0.14), p=0.025). CONCLUSIONS Our results demonstrated that higher lean muscle volume was significantly associated with higher vBMD in the lumbosacral lesions in women. This association was not observed in men. This might indicate gender differences should be considered for the assessment of osteosarcopenia in spine surgery patients. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Methods to measure bone quality using opportunistic imaging have recently been developed, including quantitative computed tomography (QCT), which allows for site-specific volumetric bone mineral density (vBMD) measurement, such as pedicles or endplates. Studies have shown these site-specific QCT measurements had more predictive value for site-specific complications than standard L1/2 measurements. Recently, MRI-based assessments of the vertebral bone quality (VBQ), which measures trabecular bone quality, were also introduced. However, there have been few studies that investigate the association between site-specific MRI bone assessment and osteoporosis related complications in patients undergoing lumbar interbody fusion. In this work, we created a novel site-specific MRI-based assessment of the endplate bone quality (EBQ) and assessed its predictive value for severe cage subsidence following standalone lateral lumbar interbody (SA-LLIFF) fusion. PURPOSE The purpose is to introduce a novel MRI-based site-specific bone quality assessment, EBQ, and investigate the predictive value of EBQ for severe cage subsidence after SA-LLIF compared with standard VBQ. STUDY DESIGN/SETTING A retrospective observational study at a single academic institution. PATIENT SAMPLE Patients undergoing SA-LLIF between 2008-2019 with available preoperative CT and T1-weighted MRIs of the lumbar spine as well as postoperative lumbar radiographs or CTs. OUTCOME MEASURES Severe cage subsidence (Grade 2 or 3) within 5-14 month after SA-LLIF. METHODS We retrospectively reviewed the records of SA-LLIF patients. Cage subsidence was assessed using the classification of Marchi et al. and severe cage subsidence was defined as grade 2 or 3. We measured VBQ as shown in the original article by Ehresman et al. EBQ was measured using preoperative non-contrast T1-weighted MRIs of the lumbar spine. The regions of interest were the subchondral bones of upper and lower endplates at the operated level, and the average signal intensity of both endplates was divided by that of the cerebrospinal fluid space at the level of L3. As a confounding factor, vBMD was measured using asynchronous QCT. Bivariate and multivariable analysis with generalized linear mixed models were performed with setting binary severe subsidence as the outcome. Statistical significance was set at p=0.05. The quality of fit was assessed using Akaike's information criterion. RESULTS A total of 205 levels in 89 patients were included in the final analysis. There were 50 levels (24.4%) which demonstrated severe subsidence. QCT-vBMD was significantly lower in severe subsidence group (Mean (SD) 97.4 (34.4) vs 110.1(33.4), p=0.021). Both VBQ and EBQ were significantly higher in severe subsidence group (VBQ: Mean (SD) 2.67 (1.08) vs 2.39 (0.44), p=0.010; EBQ Mean (SD) 5.09 (2.20) vs 4.31 (1.09), p=0.001). In multivariate analyses adjusted with QCT-vBMD, EBQ showed significant association with severe cage subsidence (OR (95% confidential interval) = 1.94 (1.36-3.63), p=0.038), whereas VBQ only showed a marginal trend (p=0.071). The EBQ based prediction model for severe subsidence showed better goodness of fit compared to VBQ based model. (AIC EBQ 190 vs VBQ 192). CONCLUSIONS We introduced a novel MRI-based site-specific bone quality assessment. High EBQ was an independent factor for severe cage subsidence after SA-LLIF and the EBQ-based model showed better goodness of fit compared to VBQ-based model. Given the availability of preoperative MRIs, EBQ assessment prior to SA-LIFF may provide insight into a patient's risk for severe subsidence. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Opioid prescribing for patients undergoing orthopedic procedures has been identified as a major contributor to the current opioid crisis in the United States. The rising awareness and more restrictive prescribing guidelines are beginning to affect the practice of medicine. Physicians are looking for alternative methods to effectively control acute pain and improve the treatment of chronic opioid patients. In line with these efforts, hospitals are establishing interventions and policies to address the national epidemic at the institutional level. Our hospital implemented new clinical, regulatory and policy guidelines in 2017 directed toward minimizing opioid use and prescribing while providing adequate analgesia after orthopedic surgery. These included clinical guidelines for managing opioid naive and opioid tolerant patients and/or those with substance abuse disorder, educational programs for patients and prescribers, and surgery-specific prescribing recommendations to limit unnecessary prescribing of opioids. PURPOSE The aim of this study was to describe changes in opioid use and prescribing associated with the implementation of opioid minimizing initiatives in patients undergoing multilevel lumbar fusion. STUDY DESIGN/SETTING A retrospective before-and-after analysis of patients who underwent multilevel lumbar fusion at an orthopedic surgery specialty hospital in New York City. PATIENT SAMPLE Multilevel lumbar fusion patients. OUTCOME MEASURES The primary outcome was postoperative opioid consumption during the hospital stay and the opioid prescribed upon hospital discharge. The secondary outcomes were length of hospital stay (LOS), opioid-induced side effects, and numeric rating scale (NRS) pain scores. Methods The study included data collected between January 1, 2016 – December 31, 2016 (prior to institutional implementation) and between January 1 – December 31, 2019, (after full institutional implementation). The electronic medical records and office notes were retrospectively reviewed for opioid use before and after surgery, and converted to equianalgesic doses (morphine equivalent dose, MED and expressed as milligrams of morphine per day, mg/day). Demographic and perioperative characteristics were compared between the intervention group and control cohort using Wilcoxon signed rank test for continuous variables and fisher's exact test for dichotomous variables and set the statistical significance at p Results A total of 268 multilevel lumbar fusion patients were included in this analysis. 141 (52.6%) patients had surgery in 2016 and 127 (47.4%) underwent surgery in 2019. We found a statically significantly lower opioid consumption during the hospital stay (p Conclusions This study found that after the clinical and policy interventions, opioid consumption, prescribed opioids upon hospital discharge and opioid-related side effects were lower. Despite these gains, there were no changes in reported pain associated with surgery and LOS was unchanged. Our findings demonstrate the efficacy of institutional implementation of a set of interventions to address the national opioid epidemic at the local level. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Postoperative dysphagia and dysphonia (PDD) are prevalent complications after anterior cervical discectomy and fusion (ACDF). Identification of risk factors for these complications is necessary for effective prevention. Recently, patient reported outcome measures (PROM) have been used to determine PDD after ACDF. The Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) is a validated PROM that specifically assesses dysphagia and dysphonia after anterior cervical spine surgery. PURPOSE To identify the perioperative risk factors for PDD utilizing the HSS-DDI. STUDY DESIGN/SETTING Observational study of prospectively collected data at a single academic institution. PATIENT SAMPLE Patients undergoing anterior cervical discectomy and fusion from 2015 to 2019 who enrolled in the prospective data collection. OUTCOME MEASURE The HSS-DDI administered 4 weeks, 8 weeks, and 4-6 months after surgery. METHODS As potential risk factors, the data on demographic factors, analgesic medications, history of psychiatric illness, preoperative sagittal alignment, surgical factors, preoperative diagnoses, and preoperative Neck Disability Index (NDI) scores were collected. Bivariate and multivariable regression analyses utilizing the Tobit model were conducted. RESULTS 291 patients were included in the final analysis. The median HSS-DDI at 4-weeks, 8 weeks, and 4-6 months postoperatively, were 80.7, 92.7, and 98.4, respectively. Multivariable analysis demonstrated that current smoking, previous cervical spine surgery, preoperative C2-7 angle, upper level surgery, multilevel surgery, opioid use, and a high preoperative NDI score, were independent contributing factors to a low HSS-DDI score at 4-weeks follow-up. Intraoperative topical steroid use was an independent protective factor for a low HSS-DDI score. Opioid use and high NDI score remained independent factors at 4-6 months. Sub-domain analysis demonstrated that prior cervical surgery, preoperative C2-7 angle, multilevel surgery, and intraoperative topical steroid use were significant for dysphagia only. Current smoking was significant for dysphonia only. CONCLUSIONS Our results showed that preoperative opioid use and a high preoperative NDI score are novel independent risk factors for postoperative dysphagia and dysphonia in addition to other known factors.

Background context Hemodynamically significant bradycardia and cardiac arrest (CA) are rare under general anesthesia (GA) for spine surgery. Although patient risks are well defined, emerging data implicate surgical, anesthetic and neurologic factors which should be considered in the immediate management and decision to continue or terminate surgery. Purpose To characterize causes and contributors to significant arrhythmias during spine surgery. We also provide an updated literature review to inform spine care teams and aid in the management of intraoperative bradycardia and CA. Study design Case series and literature review Patient sample Six patients who underwent spine surgery from 03/2016 to 01/2020 at a single institution and developed unexpected hemodynamically significant arrhythmia Outcome measures Our primary outcome was to identify potential risk factors of interest for significant arrhythmia during spine surgery. Methods Medical records of patients who underwent spine surgery from 03/2016 to 01/2020 at a single institution and developed unexpected hemodynamically significant arrhythmia during spine surgery were identified from a departmental Quality Assurance Database. We evaluated the presence/absence of patient, surgical, anesthetic and neurologic risk factors and estimated the most likely etiology of the event, immediate and subsequent management, whether surgery was postponed or continued and outcomes. Results We found a temporal relationship of bradyarrhythmia and CA after somatosensory evoked potential (SSEP) stimulation in 4/6 cases and pharmacy/polypharmacy in 2/6. Surgery was completed in 4/6 patients, and terminated in 2/6 (subsequently completed in both). We found no adverse outcomes in any patients. Our literature review predominately identified case reports for guidance to support decision making. New literaure suggests peripheral nerve blocks and opioid-sparing anesthetic agents should also be considered. Conclusions Significant bradycardia and CA during spine surgery does not always require termination of the surgical procedure. Decision making should be undertaken in each case individually, with an updated awareness of potential causes. The study also suggests the need for large prospective studies to adequately assess incidence, risk factors and outcomes.

OBJECTIVEOsteoporosis is a metabolic bone disease that increases the risk for fragility fractures. Screening and diagnosis can be achieved by measuring bone mineral density (BMD) using quantitative CT tomography (QCT) in the lumbar spine. QCT-derived BMD measurements can be used to diagnose osteopenia or osteoporosis based on American College of Radiology (ACR) thresholds. Many reports exist regarding the disease prevalence in asymptomatic and disease-specific populations; however, osteoporosis/osteopenia prevalence rates in lumbar spine fusion patients without fracture have not been reported. The purpose of this study was to define osteoporosis and osteopenia prevalence in lumbar fusion patients using QCT.METHODSA retrospective review of prospective data was performed. All patients undergoing lumbar fusion surgery who had preoperative fine-cut CT scans were eligible. QCT-derived BMD measurements were performed at L1 and L2. The L1–2 average BMD was used to classify patients as having normal findings, osteopenia, or osteoporosis based on ACR criteria. Disease prevalence was calculated. Subgroup analyses based on age, sex, ethnicity, and history of abnormal BMD were performed. Differences between categorical groups were calculated with Fisher’s exact test.RESULTSOverall, 296 consecutive patients (55.4% female) were studied. The mean age was 63 years (range 21–89 years). There were 248 (83.8%) patients with ages ≥ 50 years. No previous clinical history of abnormal BMD was seen in 212 (71.6%) patients. Osteopenia was present in 129 (43.6%) patients and osteoporosis in 44 (14.9%). There were no prevalence differences between sex or race. Patients ≥ 50 years of age had a significantly higher frequency of osteopenia/osteoporosis than those who were < 50 years of age.CONCLUSIONSIn 296 consecutive patients undergoing lumbar fusion surgery, the prevalence of osteoporosis was 14.9% and that for osteopenia was 43.6% diagnosed by QCT. This is the first report of osteoporosis disease prevalence in lumbar fusion patients without vertebral fragility fractures diagnosed by QCT.

STUDY DESIGN Retrospective state database analysis. OBJECTIVE To quantify the 30- and 90-day emergency department (ED) utilization and inpatient readmission rates after primary cervical arthrodesis, to stratify these findings by surgical approach, and to describe risk factors and conditions precipitating these events. SUMMARY OF BACKGROUND DATA Limited data exist on ED utilization and hospital readmission rates after cervical spine arthrodesis. METHODS The New York State all-payer health-care database was queried to identify all 87,045 patients who underwent primary subaxial cervical arthrodesis from 1997 through 2012. Demographic data and clinical information were extracted. Readmission data were available for the entire study period, whereas ED utilization data collection began later and was therefore analyzed starting in 2005. Incidences of these events within 30 and 90 days of discharge as well as trends over time were tabulated. The conditions prompting these encounters were also collected. Data were analyzed with respect to surgical approach. RESULTS The hospital readmission rate was 4.2% at 30 days and 6.2% at 90 days postoperatively. Approximately 6.2% of patients were managed in the ED without inpatient admission within 30 days and 11.3% within 90 days of surgery. The most common conditions prompting such events were dysphagia or dysphonia, respiratory complications, and infection. ED utilization and readmission rates were lowest after anterior surgeries. A preoperative Charlson Comorbidity Index of 1 or greater and traumatic pathologies were associated with increased risk of subsequent ED utilization or hospital readmission. Thirty-day hospital readmission rates declined after 2010, whereas 30-day ED utilization continued to increase. CONCLUSION Patient comorbidities, traumatic pathologies, and surgical approach are associated with increased postoperative complications. Anterior procedures carry the lowest risk, followed by posterior and then circumferential. Awareness of these findings should help to encourage development of strategies to minimize the rate of postoperative ED utilization and hospital readmission. LEVEL OF EVIDENCE 3.

Background Lateral lumbar interbody fusion (LLIF) has often been associated with postoperative lumbar plexus symptoms, including pain, paresthesia, and motor deficits in the lower extremities, especially the anterior thigh regions. Previous studies have suggested that LLIF procedures at L4-L5 will be associated with a greater motor deficit rate than other levels. However, it is unclear which level has the greatest risk of pain and paresthesia. The purpose of the present retrospective observational study was to investigate the difference in the incidence of early postoperative thigh symptoms (pain and paresthesia) stratified by procedure level among patients who had undergone standalone LLIF. Methods We reviewed the data from consecutive patients who had undergone LLIF at a single academic institution. A total of 285 standalone LLIF cases without preoperative motor deficits were identified. The incidence of postoperative thigh pain and paresthesia at the 6-week postoperative follow-up examination was assessed at all levels from T12-L1 to L4-L5. Results A total of 81 patients (28.4%) had anterior thigh pain and 62 (21.8%) had anterior thigh paresthesia. The presence of ≥3 levels fused (odds ratio [OR], 2.96; P = 0.004) and surgery at L2-L3 (OR, 2.59; P = 0.001) were significant risk factors for postoperative anterior thigh paresthesia on univariate analysis but were not associated with anterior thigh pain. Multivariate analyses demonstrated that only surgery L2-L3 was an independent risk factor for anterior thigh paresthesia (OR, 2.09; P = 0.049). Conclusions Our results have demonstrated that standalone LLIF at the L2-L3 was significantly associated with a greater incidence of postoperative anterior thigh paresthesia but that the incidence of postoperative thigh pain showed no significant association with any operative level.

The rate of cervical spinal fusion has been increasing significantly. However, there is a paucity of literature describing trends based on surgical approach using complete population databases. We investigated the approach-based trends in epidemiology, indications, and in-hospital outcomes of cervical spinal fusion.New York's Statewide Planning and Research Cooperative System database was queried to identify patients who underwent primary subaxial cervical fusion from 1997 to 2012. Demographic and clinical information was obtained. Subgroup analyses were performed based on surgical approach: anterior (A), posterior (P), and circumferential (C).A total of 87,045 cervical fusions were included. Over the study period, the population-adjusted annual fusion rate increased from 23.7 to 50.6 per 100,000 population (P0.001). A fusion was most common (85.2%), followed by P (12.3%), and C (2.5%). Mean ages were 49.8 ± 11.9, 59.9 ± 15.2, and 55.1 ± 14.5 years (P0.001), respectively. Although rates remained steady among younger patients, they increased for older patients. Overall, degenerative conditions were the predominant indications for surgery and increased in rate over time. The mean length of stay was: A, 3.1 ± 10.5; P, 9.1 ± 14.1; and C, 14.1 ± 22.5 days (P0.001). Rates of in-hospital complications were A, 3.0%; P, 10.5%; and C, 18.9% (P0.001), and mortality was A, 0.3%, P, 1.8%, and C, 2.5% (P0.001).The rate of subaxial spinal fusions increased 114% from 1997 to 2012 in New York State. Rates remained stable in younger patients but increased in the older population. Preoperative indications and postoperative courses differed significantly among the various approaches, with patients undergoing anterior fusion having better short-term outcomes.

BACKGROUND CONTEXT Lateral lumbar interbody fusion (LLIF) is a common treatment for degenerative spine diseases. However, implant subsidence is a prevalent complication especially in stand-alone cases, which can negatively affect patient outcomes. The novel 3D-printed titanium (Ti) cages with porous architecture are reportedly more osteoconductive, maximize bone-to-implant contact, and have more compressive shear strength under physical force. Nevertheless, the subsidence rate of these new Ti cages compared to polyetheretherketone (PEEK) cages has not been investigated in standalone cases. PURPOSE This study aims to compare the early subsidence rate (6-12 months) of standalone Ti vs PEEK interbody cages after LLIF. STUDY DESIGN/SETTING Retrospective study. PATIENT SAMPLE A total of 113 patients and 186 levels. OUTCOME MEASURES Early cage subsidence. METHODS A retrospective study of 113 patients (186 levels) who underwent LLIF surgery with Ti or PEEK cages was conducted. Early subsidence was measured in each treated level using the Marchi et al. classification in radiographs or CT scans acquired at 6-12 months follow-up. Multivariate logistic regression analyses with generalized mixed models, setting subsidence as the outcome variable and including cage type (Ti vs PEEK) as well as significant and trending variables (p RESULTS In total, 51 female and 62 male patients were analyzed. The median (IQR) age at surgery was 60.0 (51.0-70.0) years. Of the 186 levels, 119 levels were treated using PEEK and 67 levels with Ti cages. The overall subsidence rate for Grades I-III was significantly less in the Ti vs the PEEK group (p=0.003). For high-grade subsidence (Grade II or III), Ti cages also demonstrated a subsidence rate (3.0%) that was significantly less compared to PEEK cages (18.5%)(p= 0.002). Multivariate analysis showed that patients treated with Ti cages were less likely to develop severe subsidence compared to those treated with PEEK (OR= 0.05, 95%CI= 0.01, 0.30)(p= 0.001). CONCLUSIONS Our study demonstrated that 3D-printed novel Ti cages had a significantly lower early subsidence rate compared to PEEK cages in standalone LLIF patients. FDA DEVICE/DRUG STATUS Titanium and PEEK Cage (Approved for this indication).

BACKGROUND CONTEXT The importance of bone quality assessment in spine surgery is well recognized. The current gold standard for assessing bone mineral density is dual-energy X-ray absorptiometry (DEXA), however the majority of patients undergoing spinal fusion do not have preoperatively available DEXA data. Furthermore, DEXA has been shown to overestimate BMD in patients with spinal degenerative disease and obesity. Consequently, alternative radiographic measurements using data routinely gathered during preoperative evaluation of spine patients have been explored for the evaluation of bone quality and fracture risk. Opportunistic quantitative computed tomography and more recently the MRI-based vertebral bone quality (VBQ) score both have been shown to correlate with DEXA T-scores and predict osteoporotic fractures. However, to date the correlation between those two modalities has not been studied. PURPOSE The objective of this study was to assess whether the recently described novel VBQ score can predict the prevalence of QCT based osteopenia/osteoporosis and to evaluate the correlation between VBQ and spine QCT BMD measurements. STUDY DESIGN/SETTING Retrospective study of lumbar spinal fusion patients from a single, academic institution. PATIENT SAMPLE Patients undergoing lumbar spinal fusion from 2014-2019 with available preoperative CT and T1-weighted MRIs of the lumbar spine. OUTCOME MEASURES VBQ correlation to BMD. METHODS For BMD assessment, asynchronous quantitative computed tomography (QCT) measurements of L1-L2 were performed. An elliptical region of interest was placed anteriorly in the trabecular bone at mid-vertebral height and displaced from the vertebral cortex. The average BMD of L1-L2 was calculated and patients were categorized as either normal BMD (>120 mg/cm3) or osteopenic/osteoporotic ( RESULTS A total of 198 patients (53% female) were included in the study. The mean age was 62 years and the mean BMI was 28.2 kg/m2. The inter-observer reliability of the VBQ measurements was excellent (ICC of 0.90; 95% confidence interval: 0.82, 0.95). When comparing the patients with normal QCT BMD to those with osteopenia/osteoporosis, no significant differences existed in terms of sex, race, and BMI. However, the patients with osteopenia/osteoporosis were significantly older compared to the patients with normal BMD (64.9 vs 56.7 years, p CONCLUSIONS We found that the VBQ score significantly differentiates patients with normal BMD vs osteopenic/osteoporotic BMD based on QCT. However, the correlation between both modalities was only moderate suggesting VBQ might not measure bone density only. Due to the fact that QCT and more recently VBQ scores have both been shown to predict osteoporotic fractures, the weak correlation of the two modalities suggests that VBQ might not solely be a measurement of bone density, but rather bone quality. Since the two modalities seem to reflect different properties of bone, VBQ may be an interesting adjunct to clinically performed bone density measurements, rather than a substitution. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Anterior (ALIF) and lateral (LLIF) lumbar interbody fusion is associated with significant postoperative pain, opioid consumption and length of stay (LOS). Transversus abdominis plane (TAP) blocks improve these outcomes in other surgical subtypes but have not been applied to spine surgery. PURPOSE To describe associations between TAP block and outcomes after ALIF/LLIF. STUDY DESIGN/SETTING A retrospective analysis of patients who underwent primary ALIF or LLIF at an orthopedic specialty hospital. PATIENT SAMPLE A total of 250 consecutive patients who underwent primary ALIF or LLIF between January 2016 and December 2019. OUTCOME MEASURES LOS, pain scores, opioid consumption and opioid-related side effects METHODS The electronic medical records of 129 patients who underwent ALIF or LLIF with TAP block were compared to 121 patients who did not. All patients were cared for under a standardized perioperative care pathway with comprehensive multimodal analgesia. Differences in patent demographics, surgical factors, LOS, opioid consumption, opioid-related side-effects and pain scores were compared in bivariable and multivariable regression analyses. RESULTS In bivariable analyses, TAP block was associated with a significantly shorter LOS, less postoperative nausea/vomiting, and lower opioid consumption in the post-anesthesia care unit (PACU). In multivariable analyses, TAP block was associated with significantly shorter LOS (β-12 hours, 95% CI (-22, -2 hours); p=0.021). Preoperative opioid use was a strong predictive factor for higher opioid consumption in the PACU, opioid use in the first 24 hours after surgery, and longer LOS. We did not find significant differences in pain scores at any times between the groups. CONCLUSIONS TAP block may represent an effective addition to pain management and opioid reducing strategies and improve outcomes after ALIF/LLIF. Prospective trials are warranted to further explore these associations. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Agreement between patients and surgeons regarding expectations of lumbar surgery may vary depending on whether expectations are for improvement in physical or mental health. Focusing patient-surgeon communication on health domains where there is more disagreement should be a priority before surgery. PURPOSE To compare agreement within the patient-surgeon pair for expected improvement in domains of physical and mental health, STUDY DESIGN/SETTING Cross-sectional, tertiary spine. PATIENT SAMPLE This study included 402 lumbar surgery patient-surgeon pairs. OUTCOME MEASURES HSS Lumbar Spine Surgery Expectations Survey. METHODS Patients of five spine surgeons were interviewed preop and completed the ODI and the valid 20-item Expectations Survey, which is composed of four domains: personal activities (eg, sit); complex function (eg, exercise, stop condition from getting worse); psychological well-being (eg emotional stress); and skeletal function (eg, balance). The survey asks how much improvement is expected for each item with response options of complete to no improvement, and a total score and four domain scores are generated (possible score range 0-100, higher is greater expectations). Surgeons completed an identical survey asking them to rate expected improvement for each item for each patient, yielding similar total and domain scores. Agreement within the patient-surgeon pair was measured with the intraclass correlation coefficient (ICC), range 0-1.0 (0-.20 poor; .21-.40 fair; .41-60 moderate; .61-.80 good; .81-1.0 excellent agreement). Differences between patients’ and surgeons’ scores were then assessed in multivariable models controlling for psychosocial and surgical characteristics. RESULTS Mean age was 55, 55% were men, 21% were non-white race/ethnicity, 79% had degenerative conditions, and mean ODI score was 53 (range 4-84). Patients and surgeons independently completed the survey within 10 days preop. Patients’ mean survey scores were greater than surgeons’ scores for each domain: personal activities 65 vs 50; complex function 84 vs 66; psychological well-being 74 vs 58; and skeletal function 69 vs 51 (p CONCLUSIONS Agreement between patients’ and surgeons’ expectations was poor-to-good with patients expecting greater improvement in all domains. Agreement was similar for physical and mental health expectations, but was markedly worse for complex functions. Greater disability was most consistently associated with less agreement for all domains, indicating that disability impacts perceptions of all aspects of health. Thus preop discussions should consider disability when addressing expectations for both physical and mental health. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Since 2000, the annual death toll from opioid associated overdose has increased by over 300%. To reduce the opioid consumption, physicians have used alternative approaches, which have proven to not only be effective, but also reduce the side effects such as nausea, constipation, and addiction. IV acetaminophen has been shown to successfully accomplish the reduction in opioid use, however, it is an expensive alternative. Testing the efficacy of IV acetaminophen vs its oral formulation will likely modify future postoperative pain management regimens while also addressing cost-effectiveness. PURPOSE To prospectively evaluate clinical outcomes and determine the cost effectiveness of IV vs oral (PO) acetaminophen following lumbar circumferential spine surgery. We hypothesize that IV acetaminophen will perform better than PO in terms of length of stay, morphine equivalence, and change in VAS scores from baseline. STUDY DESIGN/SETTING A prospective, single-center, randomized control trial. PATIENT SAMPLE Patients between the ages of 18-85 who underwent circumferential lumbar fusion surgery, while failing conservative treatment for more than 6 months were included in the study. Patients were excluded if they had already undergone lumbar surgery at the index level(s), were diagnosed with osteoporosis, had dysphagia prohibiting oral administration, or had a history of substance abuse. OUTCOME MEASURES Outcome measures included opioid equivalence, length of hospital stay, VAS measurements, and Oswestry Disability Index (ODI) scores. METHODS Once enrolled, patients were randomized to either the IV or PO acetaminophen treatment groups. Preoperatively, patients completed a baseline analgesic regimen questionnaire, surveys including VAS, SF-12, and ODI, and were administered their first acetaminophen dose within three hours of first incision. Postoperatively, patients received seven subsequent doses of their assigned acetaminophen, with access to supplemental analgesics if needed. Analgesic usage and VAS scores were monitored until discharge. Surveys were completed at six weeks and six months follow-up. RESULTS Average daily opioid consumption for the IV group was significantly lower than the PO group during the immediate postoperative period. Average length of stay was similar between groups, 3.3 days for PO and 3.7 days for IV. VAS back and leg scores were not statistically different between groups, however, both groups experienced a decrease by more than the minimally clinically important difference (MCID) of 12 points from baseline. ODI also decreased by the MCID at the 6-month follow-up, which was defined as 12.8% for ODI. CONCLUSIONS Along with an overall reduction in opioid usage, patient-reported outcomes depict successful improvement of pain management with the use of IV acetaminophen following circumferential spinal fusion surgery. Furthermore, despite the large discrepancy between the two formulations in cost-to-perceived-benefit ratio, the significant reduction of opioid usage and, therefore, its associated costs, provides a far less dramatic divergence. The continued testing of the efficacy of IV acetaminophen vs its oral formulation will likely modify future postoperative pain management regimens while also addressing the opioid epidemic plaguing communities across the US. FDA DEVICE/DRUG STATUS OFIRMEV (Approved for this indication).