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Study Design: Retrospective analysis of prospectively enrolled patients., Objective: To evaluate the relationship between paraspinal muscle (PM) atrophy and Oswestry Disability Index (ODI) improvement after spinal fusion surgery for degenerative lumbar spondylolisthesis., Background: Atrophy of the PM is linked to multiple spinal conditions, sagittal malalignment, and increased postoperative complications. However, only limited evidence for the effect on patient-reported outcomes exists., Methods: Patients with degenerative lumbar spondylolisthesis undergoing decompression and fusion surgery were analyzed. Patients with missing follow-up, no imaging, or inadequate image quality were excluded. The ODI was assessed preoperatively and two years postoperatively. A cross-sectional area of the PM was measured on a T2-weighted magnetic resonance imaging sequence at the upper endplate of L4. On the basis of the literature, a 10-point improvement cutoff was defined as the minimum clinically important difference. Patients with a baseline ODI below the minimum clinically important difference were excluded. Logistic regression was used to calculate the association between fatty infiltration (FI) of the PM and improvement in ODI, adjusted for age, sex, and body mass index., Results: A total of 133 patients were included in the final analysis, with only two lost to follow-up. The median age was 68 years (IQR 62-73). The median preoperative ODI was 23 (IQR 17-28), and 76.7% of patients showed improvement in their ODI score by at least 10 points. In the multivariable regression, FI of the erector spinae and multifidus increased the risk of not achieving clinically relevant ODI improvement ( P =0.01 and <0.001, respectively). No significant association was found for the psoas muscle ( P =0.158)., Conclusions: This study demonstrates that FI of the erector spinae and multifidus is significantly associated with less likelihood of clinically relevant ODI improvement after decompression and fusion. Further research is needed to assess the effect of interventions., Competing Interests: A.A.S. reports royalties from Ortho Development, Corp.; private investments for Vestia Ventures MiRUS Investment, LLC, IVY II, LLC, ISPH II, LLC, ISPH 3, LLC, HS2, LLC, HSS ASC Development Network, LLC, and Centinel Spine (Vbros Venture Partners V); consulting fee from Depuy Synthes Products Inc., Clariance Inc., Kuros Biosciences AG, Ortho Development Corp., Medical Device Business Service Inc.; speaking and teaching arrangements of DePuy Synthes Products Inc.; membership of scientific advisory board of Depuy Synthes Products Inc., Clariance Inc., and Kuros Biosciences AG; Medical Device Business Service Inc. and trips/travel of Medical Device Business; research support from Spinal Kinetics Inc., outside the submitted work. Cammisa reports royalties from NuVasive Inc. Accelus; ownership interest for 4WEB Medical/4WEB Inc.; Healthpoint Capital Partners, LP; ISPH II, LLC; ISPH 3 Holdings, LLC; Ivy Healthcare Capital Partners, LLC; Medical Device Partners II, LLC; Medical Device Partners III, LLC; Orthobond Corporation; Spine Biopharma, LLC; Tissue Differentiation Intelligence, LLC; VBVP VI, LLC; VBVP X, LLC; Woven Orthopedics Technologies; consulting fees from 4WEB Medical/4WEB Inc., DePuy Synthes, NuVasive Inc., Spine Biopharma, LLC, and Synexis, LLC, Accelus; membership of scientific advisory board/other office of Healthpoint Capital Partners, Medical Device Partners II, LLC, Orthobond Corporation, Spine Biopharma, LLC, and Woven Orthopedic Technologies; and research support from 4WEB Medical/4WEB Inc., Mallinckrodt Pharmaceuticals, Camber Spine, and Centinel Spine, outside the submitted work. F.P.G. reports royalties from Lanx Inc., and Ortho Development Corp.; private investments for BCIMD; and stock ownership of Healthpoint Capital Partners, LP, outside the submitted work. A.P.H. reports research support from Kuros Biosciences AG and fellowship support from NuVasive Inc. and Kuros Biosciences BV, outside the submitted work. The remaining authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: The aim of this study was to investigate the influence of preoperatively assessed paraspinal muscle parameters on postoperative patient-reported outcomes and maintenance of cervical sagittal alignment after anterior cervical discectomy and fusion (ACDF)., Methods: Patients with preoperative and postoperative standing cervical spine lateral radiographs and preoperative cervical MRI who underwent an ACDF between 2015 and 2018 were reviewed. Muscles from C3 to C7 were segmented into 4 functional groups: anterior, posteromedial, posterolateral, and sternocleidomastoid. The functional cross-sectional area and also the percent fat infiltration (FI) were calculated for all groups. Radiographic alignment parameters collected preoperatively and postoperatively included C2-7 lordosis and C2-7 sagittal vertical axis (SVA). Neck Disability Index (NDI) scores were recorded preoperatively and at 2 and 4-6 months postoperatively. To investigate the relationship between muscle parameters and postoperative changes in sagittal alignment, multivariable linear mixed models were used. Multivariable linear regression models were used to analyze the correlations between the changes in NDI scores and the muscles' FI., Results: A total of 168 patients with NDI and 157 patients with sagittal alignment measurements with a median follow-up of 364 days were reviewed. The mixed models showed that a greater functional cross-sectional area of the posterolateral muscle group at each subaxial level and less FI at C4-6 were significantly associated with less progression of C2-7 SVA over time. Moreover, there was a significant correlation between greater FI of the posteromedial muscle group measured at the C7 level and less NDI improvement at 4-6 months after ACDF., Conclusions: The findings highlight the importance of preoperative assessment of the cervical paraspinal muscle morphology as a predictor for patient-reported outcomes and maintenance of C2-7 SVA after ACDF.

Purpose: This study aimed to investigate the impact of sarcopenia and lumbar paraspinal muscle composition (PMC) on patient-reported outcomes (PROs) after lumbar fusion surgery with 12-month follow-up (12 M-FU)., Methods: A prospective investigation of patients undergoing elective lumbar fusion was conducted. Preoperative MRI-based evaluation of the cross-sectional area (CSA), the functional CSA (fCSA), and the fat infiltration(FI) of the posterior paraspinal muscles (PPM) and the psoas muscle at level L3 was performed. Sarcopenia was defined by the psoas muscle index (PMI) at L3 (CSA Psoas [cm 2 ]/(patients' height [m]) 2 ). PROs included Oswestry Disability Index (ODI), 12-item Short Form Healthy Survey with Physical (PCS-12) and Mental Component Scores (MCS-12) and Numerical Rating Scale back and leg (NRS-L) pain before surgery and 12 months postoperatively. Univariate and multivariable regression determined associations among sarcopenia, PMC and PROs., Results: 135 patients (52.6% female, 62.1 years, BMI 29.1 kg/m 2 ) were analyzed. The univariate analysis demonstrated that a higher FI (PPM) was associated with worse ODI outcomes at 12 M-FU in males. Sarcopenia (PMI) and higher FI (PPM) were associated with worse ODI and MCS-12 at 12 M-FU in females. Sarcopenia and higher FI of the PPM are associated with worse PCS-12 and more leg pain in females. In the multivariable analysis, a higher preoperative FI of the PPM (β = 0.442; p = 0.012) and lower FI of the psoas (β = -0.439; p = 0.029) were associated with a worse ODI at 12 M-FU after adjusting for covariates., Conclusions: Preoperative FI of the psoas and the PPM are associated with worse ODI outcomes one year after lumbar fusion. Sarcopenia is associated with worse ODI, PCS-12 and NRS-L in females, but not males. Considering sex differences, PMI and FI of the PPM might be used to counsel patients on their expectations for health-related quality of life after lumbar fusion., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Abdominal aortic calcification (AAC), often found incidentally on lateral lumbar radiographs, is increasingly recognized for its association with adverse outcomes in spine surgery. As a marker of advanced atherosclerosis affecting cardiovascular dynamics, this study evaluates AAC's impact on perioperative blood loss in posterior spinal fusion (PSF)., Methods: Patients undergoing PSF from March 2016 to July 2023 were included. Estimated blood loss (EBL) and total blood volume (TBV) were calculated. AAC was assessed on lateral lumbar radiographs according to the Kauppila classification. Predictors of the EBL-to-TBV ratio (%EBL/TBV) were examined via univariable and multivariable regression analyses, which adjusted for parameters such as hypertension and aspirin use., Results: A total of 199 patients (47.2% female) were analyzed. AAC was present in 106 patients (53.3%). AAC independently predicted %EBL/TBV, accounting for an increase in blood loss of 4.46% of TBV (95% CI 1.17-7.74, p = 0.008)., Conclusions: This is the first study to identify AAC as an independent predictor of perioperative blood loss in PSF. In addition to its link to degenerative spinal conditions and adverse postoperative outcomes, the relationship between AAC and increased blood loss warrants attention in patients undergoing PSF., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Study Design: A retrospective analysis of prospectively collected data., Objective: To report the decision-making process for decompression alone (DA) and decompression and fusion (DF) at a tertiary orthopedic center and compare the operative outcomes between both groups., Background: Controversy exists around the optimal operative treatment for DLS, either with DF or DA. Although previous studies tried to establish specific indications, clinical decision-making algorithms are needed., Materials and Methods: Patients undergoing spinal surgery for DLS at L4/5 were retrospectively analyzed. A survey of spine surgeons was performed to identify factors influencing surgical decision-making, and their association with the surgical procedure was tested in the clinical data set. We then developed a clinical score based on the statistical analysis and survey results. The predictive capability of the score was tested in the clinical data set with a receiver operating characteristic (ROC) analysis. To evaluate the clinical outcome, two years follow-up postoperative Oswestry Disability Index (ODI), postoperative low back pain (LBP) (Numeric Analog Scale), and patient satisfaction were compared between the DF and DA groups., Results: A total of 124 patients were included in the analysis; 66 received DF (53.2%) and 58 DA (46.8%). Both groups showed no significant differences in postoperative ODI, LBP, or satisfaction. The degree of spondylolisthesis, facet joint diastasis and effusion, sagittal disbalance, and severity of LBP were identified as the most important factors for deciding on DA or DF. The area under the curve of the decision-making score was 0.84. At a cutoff of three points indicating DF, the accuracy was 80.6%., Conclusions: The two-year follow-up data showed that both groups showed similar improvement in ODI after both procedures, validating the respective decision. The developed score shows excellent predictive capabilities for the decision processes of different spine surgeons at a single tertiary center and highlights relevant clinical and radiographic parameters. Further studies are needed to assess the external applicability of these findings., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective study of prospective collected data., Objective: To analyze the association between intervertebral vacuum phenomenon (IVP) and clinical parameters in patients with degenerative spondylolisthesis., Summary of Background Data: IVP is a sign of advanced disc degeneration. The correlation between IVP severity and low back pain in patients with degenerative spondylolisthesis has not been previously analyzed., Methods: We retrospectively analyzed patients with degenerative spondylolisthesis who underwent surgery. Vacuum phenomenon was measured on computed tomography scan and classified into mild, moderate, and severe. A lumbar vacuum severity (LVS) scale was developed based on vacuum severity. The associations between IVP at L4/5 and the LVS scale, preoperative and postoperative low back pain, as well as the Oswestry Disability Index was assessed. The association of IVP at L4/5 and the LVS scale and surgical decision-making, defined as decompression alone or decompression and fusion, was assessed through univariable logistic regression analysis., Results: A total of 167 patients (52.7% female) were included in the study. The median age was 69 years (interquartile range 62-72). Overall, 100 (59.9%) patients underwent decompression and fusion and 67 (40.1%) underwent decompression alone. The univariable regression demonstrated a significantly increased odds ratio (OR) for back pain in patients with more severe IVP at L4/5 [OR=1.69 (95% CI 1.12-2.60), P =0.01]. The univariable regressions demonstrated a significantly increased OR for increased disability with more severe L4/L5 IVP [OR=1.90 (95% CI 1.04-3.76), P =0.04] and with an increased LVS scale [OR=1.17 (95% CI 1.02-1.35), P =0.02]. IVP severity of the L4/L5 were associated with higher indication for fusion surgery., Conclusion: Our study showed that in patients with degenerative spondylolisthesis undergoing surgery, the severity of vacuum phenomenon at L4/L5 was associated with greater preoperative back pain and worse Oswestry Disability Index. Patients with severe IVP were more likely to undergo fusion., Competing Interests: A.A.S. reports royalties from Ortho Development, Corp.; private investments for Vestia Ventures MiRUS Investment, LLC, IVY II, LLC, ISPH II, LLC, ISPH 3, LLC, HSS ASC Development Network, LLC, and Centinel Spine (Vbros Venture Partners V); consulting fee from Depuy Synthes Products, Inc., Clariance, Inc., Kuros Biosciences AG, Ortho Development Corp., Medical Device Business Service, Inc.; speaking and teaching arrangements of DePuy Synthes Products, Inc.; membership of scientific advisory board of Depuy Synthes Products, Inc., Clariance, Inc., and Kuros Biosciences AG; Medical Device Business Service, Inc. and trips/travel of Medical Device Business; research support from Spinal Kinetics, Inc., outside the submitted work. F.P.C. reports royalties from NuVasive, Inc. Accelus; ownership interest for 4WEB Medical/4WEB, Inc.; Healthpoint Capital Partners, LP; ISPH II, LLC; ISPH 3 Holdings, LLC; Ivy Healthcare Capital Partners, LLC; Medical Device Partners II, LLC; Medical Device Partners III, LLC; Orthobond Corporation; Spine Biopharma, LLC; Tissue Differentiation Intelligence, LLC; VBVP VI, LLC; VBVP X, LLC; Woven Orthopedics Technologies; consulting fees from 4WEB Medical/4WEB, Inc., DePuy Synthes, NuVasive, Inc., Spine Biopharma, LLC, and Synexis, LLC, Accelus; membership of scientific advisory board/other office of Healthpoint Capital Partners, Medical Device Partners II, LLC, Orthobond Corporation, Spine Biopharma, LLC, and Woven Orthopedic Technologies; and research support from 4WEB Medical/4WEB, Inc., Mallinckrodt Pharmaceuticals, Camber Spine, and Centinel Spine, outside the submitted work. F.P.G. reports royalties from Lanx, Inc., and Ortho Development Corp.; private investments for BCIMD; and stock ownership of Healthpoint Capital Partners, LP, outside the submitted work. A.P.H. reports research support from Kuros Biosciences AG; and fellowship support from NuVasive, Inc. and Kuros Biosciences BV, outside the submitted work. G.S. receives consulting fees from Stryker and Camber spine. The remaining authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background Context: Degenerative lumbar spondylolisthesis (DLS) is a prevalent spinal disorder, often requiring surgical intervention. Accurately predicting surgical outcomes is crucial to guide clinical decision-making, but this is challenging due to the multifactorial nature of postoperative results. Traditional risk assessment tools have limitations, and with the advent of machine learning, there is potential to enhance the precision and comprehensiveness of preoperative evaluations., Purpose: We aimed to develop a machine-learning algorithm to predict surgical outcomes in patients with degenerative lumbar spondylolisthesis (DLS) undergoing spinal fusion surgery, only using preoperative data., Study Design: Retrospective cross-sectional study., Patient Sample: Patients with DLS undergoing lumbar spinal fusion surgery., Outcome Measures: This study aimed to predict the occurrence of lower back pain (LBP) ≥4 on the numeric analogue scale (NAS) 2 years after surgery. LBP was evaluated as the average pain patients experienced at rest in the week before questioning. NAS ranges from 0 to 10, 0 representing no pain and 10 representing the worst pain imaginable., Methods: We conducted a retrospective analysis of prospectively enrolled patients who underwent spinal fusion surgery for degenerative lumbar spondylolistheses at our institution in the United States between January 2016 and December 2018. The initial patient characteristics to be included in the training of the model were chosen by clinical expertise and through a literature review and included demographic characteristics, comorbidities, and radiologic features. The data was split into a training and validation datasets using a 60/40 split. Four different machine learning models were trained, including the modern XGBoost model, logistic regression, random-forest, and support vector machine (SVM). The models were evaluated according to the area under the curve (AUC) of the receiver operating characteristics (ROC) curve. An AUC of 0.7 to 0.8 was considered fair, 0.8 to 0.9 good, and ≥ 0.9 excellent. Additionally, a calibration plot and the Brier score were calculated for each model., Results: A total of 135 patients (66% female) were included. A total of 38 (28%) patients reported LBP ≥ 4 after 2 years, representing the positive class. The XGBoost model demonstrated the best performance in the validation set with an AUC of 0.81 (95% CI 0.67-0.95). The other machine learning models performed significantly worse: with an AUC of 0.52 (95% CI 0.37-0.68) for the SVM, 0.56 (95% CI 0.37-0.76) for the logistic regression and an AUC of 0.56 (95% CI 0.37-0.78) for the random forest. In the XGBoost model age, composition of the erector spinae, and severity of lumbar spinal stenosis as were identified as the most important features., Conclusions: This study represents a novel approach to predicting surgical outcomes in spinal fusion patients. The XGBoost demonstrated a better performance compared with classical models and highlighted the potential contributions of age and paraspinal musculature atrophy as significant factors. These findings have important implications for enhancing patient care through the identification of high-risk individuals and modifiable risk factors. As the incorporation of machine learning algorithms into clinical decision-making continues to gain traction in research and clinical practice, our insights reinforce this trajectory by showcasing the potential of these techniques in forecasting surgical results., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background Context: 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., Purpose: 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., Study Design: Retrospective single center cohort study., Patient Sample: 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., Outcome Measures: Severe cage subsidence., Methods: 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., Results: 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., Conclusions: 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., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background Context: 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., Purpose: 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., Study Design/setting: Retrospective cross-sectional study., Patient Sample: 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., Outcome Measures: 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)., Methods: 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 (cm 2 /m 2 ). LL, PT, SS, PI, and SVA were determined on standing lateral radiographs. Spearman correlation was used to calculate the crude relationship between spinopelvic and muscle parameters. Multiple linear regression models with age, sex, LL, PT, SS, and SVA set as independent variables were established to determine the association with spinal muscle outcome measures., Results: A 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/m 2 . Significant positive correlations were observed between PT (ρ=0.327), SVA (ρ=0.256) and PI (ρ=0.202) and the FI PPM . Significant negative correlations were detected for the PT and the fCSA PPM (ρ=-0.202) and PT and the fCSA Psoas (ρ=-0.191). Furthermore, a negative correlation was seen for PI and SVA and FI Psoas . PT (β=0.187; p=.006), SVA (β=0.155; p=.035), age (β=0.468; p<.001) and sex (β=0.235; p<.001) significantly predict FI PPM (corrected R 2 =0.393) as independent variables., Conclusions: This 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 PPM , representing loss of muscular strength, may lead to increased pelvic retroversion and thus might be the initiating point for the development of the sagittal imbalance. These findings might challenge the well-known theory of increased pelvic retroversion being a compensatory mechanism for sagittal spinal balance. Thus, muscular weakness might be a factor involved in the development of sagittal spinal malalignment., Competing Interests: Declarations of competing interests The Authors declare that there is no conflict of interest regarding this work., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background Context: 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., Purpose: 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., Study Design/setting: Cross-sectional study using retrospectively collected data., Patient Sample: Patients undergoing lumbar fusion from 2014-2019 at a single, academic institution with available preoperative lumbar CT and T1-weighted MRIs were included., Outcome Measures: Correlation of the VBQ score with BMD measured by QCT, and association between VBQ score and presence of osteopenia/osteoporosis., Methods: Asynchronous QCT measurements were performed. The average L1-L2 BMD was calculated and patients were categorized as either normal BMD (>120 mg/cm 3 ) or osteopenic/osteoporotic (≤120 mg/cm 3 ). The VBQ score was calculated by dividing the median signal intensity of the L1-L4 vertebral bodies by the signal intensity of the cerebrospinal fluid on midsagittal T1-weighted MRI images. Inter-observer reliability testing of the VBQ measurements was performed. Demographic data and the VBQ score were compared between the normal and osteopenic/osteoporotic group. To determine the area-under-curve (AUC) of the VBQ score as a predictor of osteopenia/osteoporosis receiver operating characteristic (ROC) analysis was performed. VBQ scores were compared with QCT BMD using the Pearson's correlation., Results: A total of 198 patients (53% female) were included. The mean age was 62 years and the mean BMI was 28.2 kg/m 2 . The inter-observer reliability of the VBQ measurements was excellent (ICC of 0.90). When comparing the patients with normal QCT BMD to those with osteopenia/osteoporosis, the patients with osteopenia/osteoporosis were significantly older (64.9 vs. 56.7 years, p<.0001). The osteopenic/osteoporotic group had significantly higher VBQ scores (2.6 vs. 2.2, p<.0001). The VBQ score showed a statistically significant negative correlation with QCT BMD (correlation coefficient = -0.358, 95% CI -0.473 - -0.23, p<.001). Using a VBQ score cutoff value of 2.388, the categorical VBQ score yielded a sensitivity of 74.3% and a specificity of 57.0% with an AUC of 0.7079 to differentiate patients with osteopenia/osteoporosis and with normal BMD., Conclusions: We 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., Competing Interests: Declarations of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: To develop a decision-making pathway for primary SA-LLIF. Furthermore, we analyzed the agreement of this pathway and compared outcomes of patients undergoing either SA-LLIF or 360-LLIF., Method: A decision-making pathway for SA-LLIF was created based on the results of interviews/surveys of senior spine surgeons with over 10 years of experience. Internal validity was retrospectively evaluated using consecutive patients undergoing either SA-LLIF or 360-LLIF between 01/2018 and 07/2020 with 3D-printed Titanium cages. An outcome assessment looking primarily at revision surgery and secondary at cage subsidence, changes in disk and foraminal height, global and segmental lumbar lordosis, duration of surgery, estimated blood loss, and length of stay was carried out., Results: 78 patients with 124 treated levels (37 SA-LLIF, 41 360-LLIF) were retrospectively analyzed. The pathway showed a direct agreement (SA-LLIF) of 100.0% and an indirect agreement (360-LLIF) of 95.1%. Clinical follow-up averaged 13.5 ± 6.5 months including 4 revision surgeries in the 360-LLIF group and none in the SA-LLIF group (p = 0.117). Radiographic follow-up averaged 9.5 ± 4.3 months, with no statistically significant difference in cage subsidence rate between the groups (p = 0.440). Compared to preoperative images, patients in both groups showed statistically significant changes in disk height (p < 0.001), foraminal height (p < 0.001), as well as restoration of segmental lordosis (p < 0.001 and p = 0.018). The SA-LLIF group showed shorter duration of surgery, less estimated blood loss and shorter LOS (p < 0.001)., Conclusion: The proposed decision-making pathway provides a guide to adequately select patients for SA-LLIF. Further studies are needed to assess the external applicability and validity., Level of Evidence Iii: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: 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., Methods: 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., Results: 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 (P < 0.001) 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)., Conclusions: 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., (Copyright © 2021. Published by Elsevier Inc.)

Background: 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., Methods: 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 P < 0.05., Results: 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)., Conclusions: 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 (P < 0.0001). 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., (Copyright © 2021. Published by Elsevier Inc.)

Purpose: This study aims to compare the early subsidence rate (6-12 months) of standalone novel 3D-printed titanium (Ti) versus polyetheretherketone (PEEK) interbody cages after lateral lumbar interbody fusion (LLIF)., Method: 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 < 0.10) in univariate analyses, were conducted., 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 versus 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)., Conclusion: Our study demonstrated that 3D-printed novel Ti cages had a significantly lower early subsidence rate compared to PEEK cages in standalone LLIF patients., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Although the effect of lumbar spinal stenosis (LSS) on the lower extremities is well documented, limited research exists on the effect of spinal stenosis on the posterior paraspinal musculature (PPM). Similar to neurogenic claudication, moderate to severe spinal canal compression can also interfere with the innervation of the PPM, which may result in atrophy and increased fatty infiltration (FI). This study aims to assess the association between LSS and atrophy of the PPM. Retrospective cross-sectional study. Patients undergoing MRI scans at a tertiary orthopedic center for low back pain or as part of a preoperative evaluation. The functional cross-sectional area (fCSA) and percent fatty infiltration (FI) of the PPM at L4. Lumbar MRIs of patients at a tertiary orthopedic center indicated due to lower back pain (LBP) or as a presurgical workup were analyzed. Patients with previous spinal fusion surgery or scoliosis were excluded. LSS was assessed according to the Schizas classification at all lumbar levels. The cross-sectional area of the PPM was measured on a T2-weighted MRI sequence at the upper endplate of L4. The fCSA and fatty infiltration (FI) were calculated using custom software. Crude differences in FI and fCSA between patients with no stenosis and at least mild stenosis were tested with the Wilcoxon signed-rank test. To account for possible confounders, a multivariable linear regression model was used to adjust for age, sex, body mass index (BMI), and disc degeneration. A subgroup analysis according to MRI indication was performed. A total of 522 (55.7% female) patients were included. The median age was 61 years (IQR: 51–71). The greatest degree of moderate and severe stenosis was found at L4/5, 15.7%, and 9.2%, respectively. Stenosis was the least severe at L5/S1 and was found to be 2% for moderate and 0.2% for severe stenosis. The Wilcoxon test showed significantly increased FI of the PPM with stenosis at any lumbar level (p<.001), although no significant decrease in fCSA was observed. The multivariable regression model showed a significant increase in FI with increased LSS at L1/2, L2/3, and L3/4 (p=.013, p<.01 and p=.003). The severity of LSS at L4/5 showed a positive association with the fCSA (p=.019). The subgroup analysis showed, the effect of LSS was more pronounced in nonsurgical patients than in patients undergoing surgery. In this study, we demonstrated a significant and independent association between LSS and the composition of the PPM, which was dependent on the level of LSS relative to the PPM. In addition to neurogenic claudication, patients with LSS might be especially susceptible to axial muscle wasting, which could worsen LSS due to increased spinal instability, leading to a positive feedback loop. [ABSTRACT FROM AUTHOR]

Bone quality is increasingly being recognized in the assessment of fracture risk. Nonenzymatic collagen cross‐linking with the accumulation of advanced glycation end products stiffens and embrittles collagen fibers thus increasing bone fragility. Echogenicity is an ultrasound (US) parameter that provides information regarding the skin collagen structure. We hypothesized that both skin and bone collagen degrade in parallel fashion. Prospectively collected data of 110 patients undergoing posterior lumbar fusion was analyzed. Preoperative skin US measurements were performed in the lumbar region to assess dermal thickness and echogenicity. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation endproducts (fAGEs). Pearson's correlation was calculated to examine relationships between (1) US and fAGEs, and (2) age and fAGEs stratified by sex. Multivariable linear regression analysis with adjustments for age, sex, body mass index (BMI), diabetes mellitus, and hemoglobin A1c (HbA1c) was used to investigate associations between US and fAGEs. One hundred and ten patients (51.9% female, 61.6 years, BMI 29.8 kg/m2) were included in the analysis. In the univariate analysis cortical and trabecular fAGEs decreased with age, but only in women (cortical: r = −0.32, p = 0.031; trabecular: r = −0.32; p = 0.031). After adjusting for age, sex, BMI, diabetes mellitus, and HbA1c, lower dermal (β = 1.01; p = 0.012) and subcutaneous (β = 1.01; p = 0.021) echogenicity increased with increasing cortical fAGEs and lower dermal echogenicity increased with increasing trabecular fAGEs (β = 1.01; p = 0.021). This is the first study demonstrating significant associations between skin US measurements and in vivo bone quality parameters in lumbar fusion patients. As a noninvasive assessment tool, skin US measurements might be incorporated into future practice to investigate bone quality in spine surgery patients. [ABSTRACT FROM AUTHOR]

Purpose: Anterior (ALIF) and lateral (LLIF) lumbar interbody fusion is associated with significant postoperative pain, opioid consumption and length of stay. Transversus abdominis plane (TAP) blocks improve these outcomes in other surgical subtypes but have not been applied to spine surgery. A retrospective study of 250 patients was performed to describe associations between TAP block and outcomes after ALIF/LLIF. 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, length of stay (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 h, 95% CI (− 22, − 2 h); p = 0.021). Preoperative opioid use was a strong predictive factor for higher opioid consumption in the PACU, opioid use in the first 24 h after surgery and longer LOS. We did not find significant differences in pain scores at any times between the groups. Conclusion: 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. [ABSTRACT FROM AUTHOR]

Degenerative lumbar spondylolisthesis (DLS) is a prevalent spinal condition that can result in significant disability. DLS is thought to result from a combination of disc and facet joint degeneration, as well as various biological, biomechanical, and behavioral factors. One hypothesis is the progressive degeneration of segmental stabilizers, notably the paraspinal muscles, contributes to a vicious cycle of increasing slippage. To examine the correlation between paraspinal muscle status on MRI and severity of slippage in patients with symptomatic DLS. Retrospective cross-sectional study at an academic tertiary care center. Patients who underwent surgery for DLS at the L4/5 level between 2016–2018 were included. Those with multilevel DLS or insufficient imaging were excluded. The percentage of relative slippage (RS) at the L4/5 level evaluated on standing lateral radiographs. Muscle morphology measurements including functional cross-sectional area (fCSA), body height normalized functional cross-sectional area (HI) of Psoas, erector spinae (ES) and multifidus muscle (MF) and fatty infiltration (FI) of ES and MF were measured on axial MR. Disc degeneration and facet joint arthritis were classified according to Pfirrmann and Weishaupt, respectively. Descriptive and comparative statistics, univariable and multivariable linear regression models were utilized to examine the associations between RS and muscle parameters, adjusting for confounders sex, age, BMI, segmental degeneration, and back pain severity and symptom duration. The study analyzed 138 out of 183 patients screened for eligibility. The median age of all patients was 69.5 years (IQR 62 to 73), average BMI was 29.1 (SD±5.1) and average preoperative ODI was 46.4 (SD±16.3). Patients with Meyerding-Grade 2 (M2, N=25) exhibited higher Pfirrmann scores, lower MF fCSA and MF HI , and lower BMI, but significantly more fatty infiltration in the MF and ES muscles compared to those with Meyerding Grade 1 (M1). Univariable linear regression showed that each cm2 decrease in MF fCSA was associated with a 0.9%-point increase in RS (95% CI -1.4 to - 0.4, p<.001), and each cm2/m2 decrease in MF HI was associated with an increase in slippage by 2.2%-points (95% CI -3.7 to -0.7, p=.004). Each 1%-point rise in ES FI and MF FI corresponded to 0.17%- (95% CI 0.05–0.3, p=.01) and 0.20%-point (95% CI 0.1–0.3 p<.001) increases in relative slippage, respectively. Notably, after adjusting for confounders, each cm2 increase in Psoas fCSA and cm2/m2 in Psoas HI was associated with an increase in relative slippage by 0.3% (95% CI 0.1–0.6, p=.004) and 1.1%-points (95% CI 0.4–1.7, p=.001). While MF fCSA tended to be negatively associated with slippage, this did not reach statistical significance (p=.105). However, each 1%-point increase in MF FI and ES FI corresponded to increases of 0.15% points (95% CI 0.05–0.24, p=.002) and 0.14% points (95% CI 0.01–0.27, p=.03) in relative slippage, respectively. This study found a significant association between paraspinal muscle status and severity of slippage in DLS. Whereas higher degeneration of the ES and MF correlate with a higher degree of slippage, the opposite was found for the psoas. These findings suggest that progressive muscular imbalance between posterior and anterior paraspinal muscles could contribute to the progression of slippage in DLS. [ABSTRACT FROM AUTHOR]

Atrophy of the paraspinal musculature (PM) as well as generalized sarcopenia are increasingly reported as important parameters for clinical outcomes in the field of spine surgery. Despite growing awareness and potential similarities between both conditions, the relationship between "generalized" and "spine-specific" sarcopenia is unclear. To investigate the association between generalized and spine-specific sarcopenia. Retrospective cross-sectional study. Patients undergoing lumbar spinal fusion surgery for degenerative spinal pathologies. Generalized sarcopenia was evaluated with the short physical performance battery (SPPB), grip strength, and the psoas index, while spine-specific sarcopenia was evaluated by measuring fatty infiltration (FI) of the PM. We used custom software written in MATLAB® to calculate the FI of the PM. The correlation between FI of the PM and assessments of generalized sarcopenia was calculated using Spearman's rank correlation coefficient (rho). The strength of the correlation was evaluated according to established cut-offs: negligible: 0–0.3, low: 0.3–0.5, moderate: 0.5–0.7, high: 0.7–0.9, and very high≥0.9. In a Receiver Operating Characteristics (ROC) analysis, the Area Under the Curve (AUC) of sarcopenia assessments to predict severe multifidus atrophy (FI≥50%) was calculated. In a secondary analysis, factors associated with severe multifidus atrophy in nonsarcopenic patients were analyzed. A total of 125 (43% female) patients, with a median age of 63 (IQR 55–73) were included. The most common surgical indication was lumbar spinal stenosis (79.5%). The median FI of the multifidus was 45.5% (IQR 35.6–55.2). Grip strength demonstrated the highest correlation with FI of the multifidus and erector spinae (rho=-0.43 and -0.32, p<.001); the other correlations were significant (p<.05) but lower in strength. In the AUC analysis, the AUC was 0.61 for the SPPB, 0.71 for grip strength, and 0.72 for the psoas index. The latter two were worse in female patients, with an AUC of 0.48 and 0.49. Facet joint arthropathy (OR: 1.26, 95% CI: 1.11–1.47, p=.001) and foraminal stenosis (OR: 1.54, 95% CI: 1.10–2.23, p=.015) were independently associated with severe multifidus atrophy in our secondary analysis. Our study demonstrates a low correlation between generalized and spine-specific sarcopenia. These findings highlight the risk of misdiagnosis when relying on screening tools for general sarcopenia and suggest that general and spine-specific sarcopenia may have distinct etiologies. [ABSTRACT FROM AUTHOR]

Background Context: 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.Purpose: 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.Study Design/setting: Retrospective cross-sectional study.Patient Sample: 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.Outcome Measures: VBMD, VBQ score, and bone microstructure parameters derived from μCT.Methods: 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/cm3 as osteopenic/osteoporotic. The VBQ score was determined by dividing the median signal intensity of the L1-L4 vertebrae by the signal intensity of the cerebrospinal fluid using sagittal T1-weighted MRI scans. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and evaluated with μCT. VBQ scores and μCT parameters were compared between the normal and the osteopenic/osteoporotic group. Correlations between VBQ score, μCT parameters and vBMD were assessed with Spearman's correlation (ρ). Receiver operating characteristic (ROC) analysis was performed to determine the VBQ score as a predictor for osteopenia/osteoporosis. Multiple linear regression analysis with vBMD L1/L2 as outcome was used to identify independent predictors from VBQ, μCT parameters and demographics.Results: 267 patients (55.8% female, age 63.3 years, BMI 29.7 kg/m2; n=118 with bone biopsy) with a prevalence of osteopenia/osteoporosis of 65.2% were analyzed. In the osteopenic/osteoporotic group the VBQ score, structured model index (SMI), and trabecular separation (Tb.Sp) were significantly higher, whereas bone volume fraction (BV/TV), connectivity density (Conn.D) and trabecular number (Tb.N) were significantly lower. There were significant correlations between VBQ and μCT parameters ranging from ρ=-.387 to ρ=0.314 as well as between vBMD and μCT parameters ranging from ρ=-.425 to ρ=.421, and vBMD and VBQ (ρ=-.300, p<.001). ROC analysis discriminated osteopenia/osteoporosis with a sensitivity of 84.7% and a specificity of 40.6% at a VBQ score threshold value of 2.18. Age, BV/TV and trabecular thickness (Tb.Th), but not VBQ, were significant independent predictors for vBMD (corrected R2=0.434).Conclusions: This 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. [ABSTRACT FROM AUTHOR]

Purpose: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.Methods: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.Results: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations.Conclusion: The literature is scarce in exploring the role of imaging parameters like ultrasound (US) as a biomarker for surgical outcomes. The purpose of this study is to investigate the associations between skin US parameters and revision surgery following spine lumbar fusion.Posterior lumbar fusion patients with 2-years follow-up were assessed. Previous fusion or revision not due to adjacent segment disease (ASD) were excluded. Revisions were classified as cases and non-revision were classified as controls. US measurements conducted at two standardized locations on the lumbar back. Skin echogenicity of the average dermal (AD), upper 1/3 of the dermal (UD), lower 1/3 of the dermal (LD), and subcutaneous layer were measured. Echogenicity was calculated with the embedded echogenicity function of our institution’s imaging platform (PACS). Statistical significance was set at p < 0.05.A total of 128 patients (51% female, age 62 [54–72] years) were included in the final analysis. 17 patients required revision surgery. AD, UD, and LD echogenicity showed significantly higher results among revision cases 124.5 [IQR = 115.75,131.63], 128.5 [IQR = 125,131.63] and 125.5 [IQR = 107.91,136.50] compared to the control group 114.3 [IQR = 98.83,124.8], 118.5 [IQR = 109.28,127.50], 114 [IQR = 94.20,126.75] respectively.The findings of this study demonstrate a significant association between higher echogenicity values in different layers of the dermis and requiring revision surgery. The results provide insights into the potential use of skin US parameters as predictors for revision surgery. These findings may reflect underlying alterations in collagen. Further research is warranted to elucidate the mechanisms driving these associations. [ABSTRACT FROM AUTHOR]

Quantitative computed tomography (QCT) is considered a standard reportable metric for the measurement of bone mineral density (BMD) of the lumbar spine. However, the sole determination of BMD is insufficient for the evaluation of overall bone health. Consequently, bone quality, apart from BMD, is increasingly recognized for its importance in the assessment of bone. Collagen cross-linking is a relevant factor for determining the tensile strength of bone. Non-enzymatic collagen cross-linking with the accumulation of advanced glycation end products (AGEs) stiffens and embrittles collagen fibers, thus increasing bone fragility and fracture risk. Despite the crucial role of AGEs in bone ageing, the relationship between AGEs and BMD is poorly understood. We hypothesized that an accumulation of AGEs, a marker of impaired bone quality, is related to decreased BMD. Prospective observational study. A total of 107 patients undergoing open posterior lumbar fusion at a single academic institution. Standardized lumbar QCT measurements were performed on preoperative CT scans using the L1/L2 average. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation end products (fAGEs), both trabecular and cortical, representing non-enzymatic collagen cross-linking. Pearson's correlation coefficients were calculated to examine crude relationships between BMD at L1/L2 and fAGEs, stratified by biological sex. Multivariable linear regression analysis with adjustments for age, sex, body mass index (BMI), diabetes and HbA1c was used to investigate associations between BMD at L1/L2 and fAGEs. Statistical significance was defined as p<0.05. A total of 107 patients (51.2% female) with a mean age of 61.2 years and a BMI of 29.9 kg/m2 were included in the final analysis, excluding patients with anti-osteoporotic drug therapy. In the univariate analysis, cortical fAGEs increased with decreasing BMD at L1/L2 (r = -0.32; p = 0.021), but only in men. In the multivariate analysis, trabecular fAGEs increased with decreasing BMD at L1/L2 after adjusting for age, sex, BMI, diabetes mellitus, and HbA1c (β = 0.99; p = 0.04). This is the first study to assess BMD and in-vivo non-enzymatic collagen cross-linking as a marker of bone quality in lumbar fusion patients. QCT-derived BMD measurements were found to be significantly associated with collagen properties in bone, such as fAGEs, which embrittle bone tissue. Our results enhance our understanding of bone health by suggesting that spine surgery patients with deficits in bone quantity may also have deficits in bone quality. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Loss of paraspinal muscle mass over time can affect spinal degeneration and promote lumbar back pain. New methods to determine muscle quantity and quality have been established, including the evaluation of the functional cross-sectional area (fCSA) and fat infiltration. However, little is known about the aging processes that occur in spinal muscle groups and sex-specific differences. Aim of this study was to determine if the processes of aging are comparable in the psoas and posterior paraspinal muscles (PPM; musclus multifidus and erector spinae), and to evaluate potential sex-related differences. Retrospective cohort study. A total of 176 patients undergoing open posterior lumbar fusion surgery. MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA), and the proportion of intramuscular fat were conducted. The regions of interest were the psoas muscle and the PPM at the superior endplate of the L4 level. The left and right side of the muscle groups were averaged and normalized by the patient's height (cm2/m2). The relationship between age and 1) psoas CSA, fCSA and fat infiltration, and 2) PPM CSA, fCSA and fat infiltration was determined by Pearson´s correlation coefficients, stratifying all analyses by sex. Statistical significance was defined as p<0.05. A total of 176 patients (59% female) were included in the final analysis with a median age of 64.7 years (IQR: 56.6-71.5]) and a median BMI of 28.2 kg/m2 (IQR: 25.1.7-32.6). The mean normalized CSA of the psoas was 4.07±0.1cm2/m2 (mean±standard deviation) and differed significantly between females (3.5±1.2cm2/m2) and males (4.9±1.0cm2/m2) likewise, the fCSA of psoas differed significantly between the sexes. The mean CSA of the PMMs was 9.9 cm2/m2 (±0.2) with no sex specific differences and showed no correlation in both groups with age. Significant differences in the fatty infiltration between men and women in the paraspinal muscles (m:41.7%; f:47.3%; p < 0.001), and there were no differences found in the psoas regarding fatty infiltration (m:5.7%; f:6.1%; p=0.631). Considering the effect of age on the fat infiltration, a significant positive correlation was observed in the PMMs for both sexes (f: r=0.651, p < 0.001; m: r=0.429, p < 0.001). In women, there was a negative correlation between age and psoas CSA (r=-0.228; p=0.02), and fat infiltration of psoas (r=-0.297; p=0.002). This study demonstrated sex-specific differences in spinal muscle morphology in relation to patient´s age. There was a decrease in fat infiltration of the psoas in women with increasing age, unlike in the posterior paraspinal musclesin which there was increased fat infiltration. This phenomenon is controversial to the assumption that fatty infiltration increases with age. The work provides further evidence on sex differences within different paraspinal muscle groups in patients undergoing posterior lumbar fusion. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Bone quality, apart from bone mineral density, is increasingly recognized for its importance in the assessment of fracture risk. Collagen cross-linking is a relevant factor for determining the tensile strength of bone. Non-enzymatic collagen cross-linking with the accumulation of advanced glycation end products (AGEs) stiffens and embrittles collagen fibers thus increasing bone fragility and fracture risk. Echogenicity is an ultrasound parameter providing information regarding the skin collagen structure and can be determined by assigning amplitudes of echoes for each pixel on a scale and segmenting the image by pixel range. Increased echogenicity in the deep portion of the dermal layer is observed with increasing age, thought to be due to disordered collagen. We hypothesized that both skin and bone collagen are aging in the same fashion and that skin ultrasound measurements would therefore be associated with in-vivo bone quality. Prospective observational study. A total of 110 patients undergoing open posterior lumbar fusion at a single academic institution. Preoperative standardized skin ultrasound measurements were performed in the lumbar region for the assessment of dermal thickness and echogenicity. Intraoperative bone biopsies from the posterior superior iliac spine were obtained and analyzed with confocal fluorescence microscopy for fluorescent advanced glycation end products (fAGEs, trabecular and cortical), representing non-enzymatic collagen cross-linking. Pearson's correlation coefficients were calculated to examine relationships between (1) US measurements and fAGEs, and (2) age and fAGEs stratified by sex. Multivariable linear regression analysis with adjustments for age, sex, BMI, diabetes and HbA1c was used to investigate associations between ultrasound measurements and fAGEs. Statistical significance was defined as p<0.05. A total of 110 patients (51.9% female) with a mean age of 61.6 years and a body mass index (BMI) of 29.8 kg/m2 were included in the final analysis, excluding patients with anti-osteoporotic drug therapy and non-Caucasian ethnicity In the univariate analysis, trabecular fAGEs increased with subcutaneous echogenicity (r = 0.31; p = 0.039); cortical and trabecular AGEs decreased with age, but only in women (cortical r = -0.32, p = 0.031; trabecular r = -0.32; p = 0.031). After adjusting for age, sex, BMI, diabetes and HbA1c, significant associations were found between cortical fAGEs and lower dermal echogenicity (β = 1.01; p = 0.012), cortical fAGEs and subcutaneous echogenicity (β = 1.01; p = 0.021), and trabecular fAGEs and lower dermal echogenicity (β = 1.01; p = 0.021). This is the first study to assess in-vivo bone quality and skin ultrasound measurements regarding non-enzymatic collagen cross-linking in lumbar spine fusion patients. Dermal ultrasound measurements were found to be significantly associated with collagen properties in bone such as fAGEs. As a noninvasive assessment tool, skin ultrasound measurements might be incorporated into future practice to investigate connective tissue aging and bone quality in spine surgery patients. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

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 naïve 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. 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. A retrospective before-and-after analysis of patients who underwent multilevel lumbar fusion at an orthopedic surgery specialty hospital in New York City. Multilevel lumbar fusion patients. 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. 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<0.05. 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<0.0001) and at discharge (p<0.0001) in 2019 compared to 2016 with statistically significant lower side effects (p=0.03) in 2019. Additionally, preoperative opioid consumption was statistically significantly lower in 2019 (p=0.003). There was no difference in the LOS and NRS pain scores in 2016 and 2019 (p=0.21 and p=0.33). 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. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

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. 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. A cross-sectional analysis of a prospectively maintained database at a single academic institution. Patients undergoing posterior lumbar fusion surgery between 2014-2020. Volumetric BMD measured by QCT in the lumbar spine and sacral ala. 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 <0.05. 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). 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. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

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. 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. Retrospective study of lumbar spinal fusion patients from a single, academic institution. Patients undergoing lumbar spinal fusion from 2014-2019 with available preoperative CT and T1-weighted MRIs of the lumbar spine. VBQ correlation to BMD. 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 (<=120 mg/cm3) based on the definition by the American College of Radiology. As previously described, the VBQ measurements were performed by placing circular regions of interest within the medullary portions of the vertebral bodies of L1-L4 and within the cerebrospinal fluid space at the level of L3 on a midsagittal T1-weighted MRI image. The VBQ score was then calculated by dividing the median signal intensity of the L1-L4 vertebral bodies by the signal intensity of the cerebrospinal fluid at the L3 level. To assess inter-observer reliability of the VBQ measurements, a validation study was performed on 37 randomly selected patients. The interclass correlation coefficient (ICC) was calculated. Demographic data and the VBQ score were compared between the normal and osteopenic/group. To determine the area-under-curve (AUC) of the VBQ score as a predictor of osteopenia/osteoporosis receiver operating characteristic (ROC) analysis was performed. VBQ scores were compared with QCT BMD using Pearson's correlation. The statistical significance level was set at p<0.05. 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<0.0001). The osteopenic/osteoporotic group had significantly higher VBQ scores (2.6 vs 2.2, p<0.0001). ROC analysis revealed that the VBQ score predicts the presence of osteopenia/osteoporosis based on QCT with an accuracy of 71% (p<0.0001). The VBQ score showed a statistically significant moderate correlation with QCT BMD (correlation coefficient = -0.358, 95% CI -0.473 - -0.23, p<0.001). 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. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

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. This study aims to compare the early subsidence rate (6-12 months) of standalone Ti vs PEEK interbody cages after LLIF. Retrospective study. A total of 113 patients and 186 levels. Early cage subsidence. 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<0.10) in univariate analyses, was conducted. 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). Our study demonstrated that 3D-printed novel Ti cages had a significantly lower early subsidence rate compared to PEEK cages in standalone LLIF patients. Titanium and PEEK Cage (Approved for this indication). [ABSTRACT FROM AUTHOR]

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. To describe associations between TAP block and outcomes after ALIF/LLIF. A retrospective analysis of patients who underwent primary ALIF or LLIF at an orthopedic specialty hospital. A total of 250 consecutive patients who underwent primary ALIF or LLIF between January 2016 and December 2019. LOS, pain scores, opioid consumption and opioid-related side effects 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. 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. 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. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]