Patients Undergoing Lumbar Fusion Surgery Research Articles

Abdominal Aortic Calcification is Associated with Degeneration of The Paraspinal Muscles - A Retrospective cross-sectional Study.

Retrospective cohort study. To analyze the relationship of abdominal aortic calcification (AAC) and a reduction in the cross-sectional area (CSA) and the fatty infiltration (FI) of the paravertebral muscles in patients undergoing lumbar fusion surgery. Both AAC and paraspinal muscle degeneration have been shown to be associated with poorer outcomes after surgical treatment of degenerative diseases of the lumbar spine. However, there is a lack of data on the association between AAC and paraspinal muscle changes in patients undergoing spine surgery. We retrospectively analyzed patients undergoing lumbar fusion for degenerative spinal pathologies. Muscular and spinal degeneration were measured on magnetic resonance imaging (MRI). AAC was classified on lateral lumbar radiographs. The association of AAC and paraspinal muscle composition was assessed by a multivariate regression analysis adjusted for age, sex, body mass index (BMI), comorbidities, and lumbar degeneration. A total of 301 patients was included. Patients with AAC showed significantly higher degrees of intervertebral disc and facet joint degeneration as well as higher total endplate scores at the L3/4 level. The univariable regression analysis showed a significant positive correlation between the degree of AAC and the FI of the erector spinae (b=0.530, P<0.001) and multifidus (b=0.730, P<0.001). The multivariable regression analysis showed a significant positive correlation between the degree of AAC and the FI of the erector spinae (b=0.270, P=0.006) and a significant negative correlation between the degree of AAC and the CSA of the psoas muscle (b=-0.260, P=0.003). This study demonstrates a significant and independent association between AAC and degeneration of the erector spinae and the psoas muscles in patients undergoing lumbar fusion. As both AAC and degeneration of paraspinal muscles impact postoperative outcomes negatively, preoperative assessment of AAC may aid in identifying patients at higher risk after lumbar surgery.

Development and external validation of a predictive model for prolonged length of hospital stay in elderly patients undergoing lumbar fusion surgery: comparison of three predictive models.

This study aimed to develop a predictive model for prolonged length of hospital stay (pLOS) in elderly patients undergoing lumbar fusion surgery, utilizing multivariate logistic regression, single classification and regression tree (hereafter, "classification tree") and random forest machine-learning algorithms. This study was a retrospective review of a prospective Geriatric Lumbar Disease Database. The primary outcome measure was pLOS, which was defined as the LOS greater than the 75th percentile. All patients were grouped as pLOS group and non-pLOS. Three models (including logistic regression, single-classification tree and random forest algorithms) for predicting pLOS were developed using training dataset and internal validation using testing dataset. Finally, online tool based on our model was developed to assess its validity in the clinical setting (external validation). The development set included 1025 patients (mean [SD] age, 72.8 [5.6] years; 632 [61.7%] female), and the external validation set included 175 patients (73.2 [5.9] years; 97[55.4%] female). Multivariate logistic analyses revealed that older age (odds ratio [OR] 1.06, p < 0.001), higher BMI (OR 1.08, p = 0.002), number of fused segments (OR 1.41, p < 0.001), longer operative time (OR 1.02, p < 0.001), and diabetes (OR 1.05, p = 0.046) were independent risk factors for pLOS in elderly patients undergoing lumbar fusion surgery. The single-classification tree revealed that operative time ≥ 232min, delayed ambulation, and BMI ≥ 30kg/m2 as particularly influential predictors for pLOS. A random forest model was developed using the remaining 14 variables. Intraoperative EBL, operative time, delayed ambulation, age, number of fused segments, BMI, and RBC count were the most significant variables in the final model. The predictive ability of our three models was comparable, with no significant differences in AUC (0.73 vs. 0.71 vs. 0.70, respectively). The logistic regression model had a higher net benefit for clinical intervention than the other models. The nomogram was developed, and the C-index of external validation for PLOS was 0.69 (95% CI, 0.65-0.76). This investigation produced three predictive models for pLOS in elderly patients undergoing lumbar fusion surgery. The predictive ability of our three models was comparable. Logistic regression model had a higher net benefit for clinical intervention than the other models. Our predictive model could inform physicians about elderly patients with a high risk of pLOS after surgery.

Development and external validation of a nomogram for predicting postoperative adverse events in elderly patients undergoing lumbar fusion surgery: comparison of three predictive models

BackgroundThe burden of lumbar degenerative diseases (LDD) has increased substantially with the unprecedented aging population. Identifying elderly patients with high risk of postoperative adverse events (AEs) and establishing individualized perioperative management is critical to mitigate added costs and optimize cost-effectiveness to the healthcare system. We aimed to develop a predictive tool for AEs in elderly patients with transforaminal lumbar interbody fusion (TLIF), utilizing multivariate logistic regression, single classification and regression tree (hereafter, “classification tree”), and random forest machine learning algorithms.MethodsThis study was a retrospective review of a prospective Geriatric Lumbar Disease Database (age ≥ 65). Our outcome measure was postoperative AEs, including prolonged hospital stays, postoperative complications, readmission, and reoperation within 90 days. Patients were grouped as either having at least one adverse event (AEs group) or not (No-AEs group). Three models for predicting postoperative AEs were developed using training dataset and internal validation using testing dataset. Finally, online tool was developed to assess its validity in the clinical setting (external validation).ResultsThe development set included 1025 patients (mean [SD] age, 72.8 [5.6] years; 632 [61.7%] female), and the external validation set included 175 patients (73.2 [5.9] years; 97 [55.4%] female). The predictive ability of our three models was comparable, with no significant differences in AUC (0.73 vs. 0.72 vs. 0.70, respectively). The logistic regression model had a higher net benefit for clinical intervention than the other models. A nomogram based on logistic regression was developed, and the C-index of external validation for AEs was 0.69 (95% CI 0.65–0.76).ConclusionThe predictive ability of our three models was comparable. Logistic regression model had a higher net benefit for clinical intervention than the other models. Our nomogram and online tool (https://xuanwumodel.shinyapps.io/Model_for_AEs/) could inform physicians about elderly patients with a high risk of AEs within the 90 days after TLIF surgery.

Developing Mixed-Effects Models to Compare the Predictive Ability of Various Comorbidity Indices in a Contemporary Cohort of Patients Undergoing Lumbar Fusion.

As incidence of operative spinal pathology continues to grow, so do the rates of lumbar spinal fusion procedures. Comorbidity indices can be used preoperatively to predict potential complications. However, there is a paucity of research defining the optimal comorbidity indices in patients undergoing spinal fusion surgery. We aimed to use modeling strategies to evaluate the predictive validity of various comorbidity indices and combinations thereof. Patients who underwent spinal fusion were queried using data from the Nationwide Readmissions Database for the years 2016 through 2019. Using comorbidity indices as predictor variables, receiver operating characteristic curves were developed for pertinent complications such as mortality, nonroutine discharge, top-quartile cost, top-quartile length of stay, and 30-day readmission. A total of 750 183 patients were included. Nonroutine discharges occurred in 161 077 (21.5%) patients. The adjusted all-payer cost for the procedure was $37 616.97 ± $27 408.86 (top quartile: $45 409.20), and the length of stay was 4.1 ± 4.4 days (top quartile: 8.1 days). By comparing receiver operating characteristics of various models, it was found that models using Frailty + Elixhauser Comorbidity Index (ECI) as the primary predictor performed better than other models with statistically significant P -values on post hoc testing. However, for prediction of mortality, the model using Frailty + ECI was not better than the model using ECI alone ( P = .23), and for prediction of all-payer cost, the ECI model outperformed the models using frailty alone ( P < .0001) and the model using Frailty + ECI ( P < .0001). This investigation is the first to use big data and modeling strategies to delineate the relative predictive utility of the ECI and Johns Hopkins Adjusted Clinical Groups comorbidity indices for the prognostication of patients undergoing lumbar fusion surgery. With the knowledge gained from our models, spine surgeons, payers, and hospitals may be able to identify vulnerable patients more effectively within their practice who may require a higher degree of resource utilization.

Abdominal aortic calcification assessed on standard lateral lumbar radiographs as a screening tool for impaired bone status in spine surgery.

The aim of this study was to determine whether the presence of abdominal aortic calcification (AAC) can predict patient bone status, represented by volumetric bone mineral density (vBMD) assessed with quantitative computed tomography (QCT). Patients undergoing lumbar fusion surgery at a tertiary care center between 2014 and 2021, with a preoperative lumbar CT-scan and lateral lumbar radiographs were retrospectively reviewed. A semi-quantitative measurement method for AAC (AAC 4, 8 and 24) was performed. QCT measurements were made for L1 and L2. Patients were divided into two groups depending on whether AAC was present. A one-way analysis of covariance was conducted to adjust for age. A multiple linear regression model was used to test if age, sex, BMI, diabetes, hypertension, smoking and presence of AAC could predict the vBMD. A receiver operating characteristic (ROC) analysis was conducted for predicting impaired bone status. 267 patients with a median age of 65.1years and BMI of 29.8kg/m2 were analyzed, 59.6% of patients had AAC. The group comparison showed that vBMD was significantly lower in patients with the presence of AAC (97.8mg/cm3 vs. 121.5mg/cm3). Age (β = - 0.360; p < 0.001) and presence of AAC (β = -0.206; p = 0.005) significantly predict vBMD as independent variables. Impaired bone status could be discriminated using AAC 4, 8 and 24 (cut off value 0.5) with a sensitivity of 70.1% and a specificity of 60.2%. The presence of AAC may identify patients at risk for impaired bone status. Preoperative evaluation of standard lumbar radiographs could be used as a potential diagnostic tool in assessing bone status.

The association between paraspinal muscle parameters and vertebral pedicle microstructure in patients undergoing lumbar fusion surgery.

Lumbar fusion surgery has become a standard procedure in spine surgery and commonly includes the posterior placement of pedicle screws. Bone quality is a crucial factor that affects pedicle screw purchase. However, the relationship between paraspinal muscles and the bone quality of the pedicle is unknown. The aim of the study was to determine the relationship between paraspinal muscles and the ex vivo bony microstructure of the lumbar pedicle. Prospectively, collected data of patients undergoing posterior lumbar fusion for degenerative spinal conditions was analyzed. Pre-operative lumbar magnetic resonance imaging (MRI) scans were evaluated for a quantitative assessment of the cross-sectional area (CSA), functional cross-sectional area (fCSA), and the proportion of intramuscular fat (FI) for the psoas muscle and the posterior paraspinal muscles (PPM) at L4. Intra-operative bone biopsies of the lumbar pedicle were obtained and analyzed with microcomputed tomography (µCT) scans. The following cortical (Cort) and trabecular (Trab) bone parameters were assessed: bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), connectivity density (CD), bone-specific surface (BS/BV), apparent density (AD), and tissue mineral density (TMD). A total of 26 patients with a mean age of 59.1years and a mean BMI of 29.8kg/m2 were analyzed. fCSAPPM showed significant positive correlations with BV/TVTrab (ρ = 0.610; p < 0.001), CDTrab (ρ = 0.679; p < 0.001), Tb.NTrab (ρ = 0.522; p = 0.006), Tb.ThTrab (ρ = 0.415; p = 0.035), and ADTrab (ρ = 0.514; p = 0.007). Cortical bone parameters also demonstrated a significant positive correlation with fCSAPPM (BV/TVCort: ρ = 0.584; p = 0.002; ADCort: ρ = 0.519; p = 0.007). FIPsoas was negatively correlated with TMDCort (ρ = - 0.622; p < 0.001). This study highlights the close interactions between the bone microstructure of the lumbar pedicle and the paraspinal muscle morphology. These findings give us further insights into the interaction between the lumbar pedicle microstructure and paraspinal muscles.

Preoperative Zung depression scale predicts outcomes in older patients undergoing short-segment fusion surgery for degenerative lumbar spinal disease.

To identify the relationship between depression measured by Zung depression rating scale (ZDRS) and postoperative outcomes (including the patients reported outcomes [PRO] and clinical outcomes) two years after short-segment fusion surgery for degenerative lumbar spinal disease in older patients (aged 75years and older). We enrolled patients who underwent short-segment fusion surgery for lumbar degenerative disease from May 2018 to June 2020. All patients were assessed for depression using the ZDRS. Patients were included in the depression group and not-depressed group based on their scores. Preoperative baseline data were collected on characteristics, comorbidities, laboratory data, pain levels (visual analogue scale [VAS]), functional status (Oswestry Disability Index [ODI]), and surgery-related variables. The primary outcomes were PRO measures, including VAS, ODI and satisfaction two years after lumbar fusion surgery. Other outcomes included postoperative complications, the length of stay, and reoperation. Univariate and multivariate analyses were performed to identify the risk factors for poor satisfaction. A total of 231 patients (201 in not-depressed and 30 in depressed group) were enrolled in this study. There were no significant differences between the two groups for baseline data. Depressed group had higher rates of choices for dissatisfaction (36.7% vs. 14.0%, p = 0.015), higher VAS scores of low back pain (2.8 ± 2.3 vs. 1.6 ± 1.7, p = 0.012), and worse functional status (31.5 ± 22.5 vs 21.8 ± 19.9, p = 0.015) than the not-depressed group. Depressed patients reported significantly higher rates of postoperative complications and readmissions. Multivariate regression analysis revealed that depression (p = 0.001) was independently associated with postoperative dissatisfaction. Preoperative depression was a risk factor for postoperative dissatisfaction, worse functional status, readmission, and complications in older patients undergoing lumbar fusion surgery. Preoperative screening using the Zung depression scale helps inform decision-making when considering fusion surgery for patients aged 75 and older.

Comparison of Perioperative Outcomes in Patients Undergoing Short-Level Lumbar Fusion Surgery After Implementing Enhanced Recovery After Surgery: A Propensity Score Matching Analysis Focusing on Young-Old and Old-Old.

There were exponentially increased studies focused on revealing the satisfactory outcomes after implementing enhanced recovery after surgery (ERAS) in patients undergoing lumbar fusion surgery. However, little attention has been paid to the impact of chronologic age alone on perioperative outcomes. In the present study, patients were dichotomized into two groups: young-old (65-79 years), and old-old (80 years and older). Given the heterogeneity and age-related comorbidities in this population and the need to compare similar groups, we performed propensity score matching for gender, body mass index (BMI), operation time, American Society of Anesthesiologists (ASA) grade, Charlson Comorbidity Index (CCI), fusion levels and frail status. Perioperative outcomes were compared between two groups. In our study, we found there were significant discrepancies in length of stay (LOS) (7.17 ± 2.81 vs 8.11 ± 3.57 days, p = 0.031) and postoperative nausea and vomiting (3.7% vs 11.0%, p = 0.038); however, there were no significant differences in C-reactive protein (21.50 ± 26.52 vs 19.22 ± 22.04 mg/L, p = 0.490), overall complication rates (24.8% vs 33.0%, p = 0.179), ambulation time (2.89 ± 1.34 vs 2.55 ± 1.49 days, p = 0.078) or removal of urinary catheter time (2.47 ± 1.44 vs 2.32 ± 1.40 days, p = 0.446). There were few differences in perioperative outcomes between young-old and old-old groups. Despite similar postoperative complication rates, the old-old group might experience longer LOS when complications occur. More importantly, current outcomes suggested that chronologic age alone does not appear to have the capacity to reflect the tolerance of elderly patients to surgery.

Effects of tizanidine and clonidine on postoperative pain after lumbar fusion surgery

ObjectivesPostoperative pain following lumbar fusion surgery is commonly reported and is associated with significant morbidity and increased use of opioids. The aim of this study is to evaluate the effects of clonidine and tizanidine on postoperative pain in patients undergoing lumbar fusion surgery. MethodsIn this double-blinded randomized study, patients referred to (XXX) for lumbar fusion surgery with ASA class I and II were included. Prior to surgery, patients were divided into three groups. Group A received one 4 mg tizanidine tablet, group B received 4 mg clonidine and group C received a placebo. After the surgery, along with demographic data, postoperative pain on a visual analogue scale (VAS), the amount of analgesic drugs required, and side effects were recorded. The data from the three groups were statistically compared using SPSS v24. ResultsA total of 75 patients were studied, and were divided equally into three groups. The postoperative pain was statistically different among the three groups at 2nd and 4th postoperative hours, p = 0.002 and p = 0.018, respectively. At 6, 12, 24 and 48 postoperative hours, VAS did not differ in the two groups, p > 0.05. Furthermore, the incidence of dizziness, nausea and vomiting, drowsiness, headache, and bradycardia were not significantly different among the three groups, p > 0.05. ConclusionsThe use of tizanidine and clonidine is likely to reduce early postoperative pain. However, may not affect the severity of pain a day or two after the surgery. Further studies at different doses are required to confirm these findings.

The Differing Effects of Ethnicity on Mental Health Outcomes Among Patients Undergoing Lumbar Fusion Surgery

Introduction Few studies have explored the effect of ethnicity on postoperative mental health outcomes. This study aims to evaluate the effect of ethnicity on changes in mental health outcomes following lumbar fusion (LF). Methods A surgical database was retrospectively reviewed for primary, single, or multilevel, lumbar fusion with posterior instrumentation procedures. Patients were propensity score matched to account for differences in demographics. 12-Item Short Form and Veterans RAND (SF-12 and VR-12) Mental Composite Score (MCS), 9-Item Patient Health Questionnaire (PHQ-9), Visual Analogue Scale (VAS) back, VAS leg, and Oswestry Disability Index (ODI) were recorded. A minimum clinically important difference (MCID) was calculated. Patients were grouped according to ethnicity: African-American, Hispanic, Asian/Other, and Caucasian. Differences between groups in baseline characteristics and mean outcome scores were evaluated. Ethnicity was assessed as a predictor of mental health outcomes and achievement of MCID was evaluated using regression analysis. Results The study included 224 patients, 43 African-American, 40 Hispanic, 22 Asian/Other, and 119 Caucasian. Groups differed in age, comorbidity score, and insurance collected (p&lt;0.05). African-Americans had the longest postoperative stay (47.3 hours; p=0.032). Groups differed in preoperative SF-12 and VR-12 MCS, but not PHQ-9 (p&lt;0.001, both). Groups demonstrated differences in postoperative SF-12 MCS (p≤0.021), VR-12 MCS (p≤0.028), PHQ-9 (p=0.009). VAS back, VAS leg, and ODI demonstrated significantly different scores (p≤0.041, all). Ethnicity was not a predictor of mental health outcomes at any timepoint and did not demonstrate an impact on achievement of MCID. Majority of individuals achieved an MCID by 1-year for all outcomes. Discussion Preoperative mental health scores demonstrated significant differences based on a patient’s ethnicity but was resolved by 2-years. Ethnicity did not demonstrate significant effects on the ability to achieve an MCID for mental health outcomes. These results suggest that patients of differing backgrounds may require alternative preoperative counseling.

P71. Should physical therapy be incorporated in patient care post 1-2 level lumbar fusions for degenerative lumbar instability? A comparative outcome analysis

BACKGROUND CONTEXT Fewer studies in the literature have examined the role of postoperative physical therapy (PT) after lumbar fusion. In the postoperative setting, much of the rehabilitation literature focuses on postdiscectomy patients. PURPOSE Evaluate and compare the changes in pain and functional scores between patients who completed physical therapy (PT) versus no-PT after their anterior or posterior 1-2 level lumbar fusions for degenerative lumbar instability. Our hypothesis was that the PT group may experience comparatively better functional and pain outcomes than their counterparts. STUDY DESIGN/SETTING Retrospective. PATIENT SAMPLE A total of 123 patients with degenerative lumbar instability. OUTCOME MEASURES Oswestry disability index (ODI) and visual analog scale (VAS). METHODS A database of patients undergoing 1-2 level lumbar fusion surgery for degenerative disease was assembled. Demographic and outcome scores such as oswestry disability index (ODI) and visual analog scale (VAS) in patients who participated in postoperative PT vs those that did not were compared. RESULTS There were 72 and 51 patients in PT and no-PT that met the inclusion criteria, respectively. There were higher numbers of females (63.8%) in PT group. No-PT group had similar numbers of males and females. Mean ages for PT and no-PT groups were 61.4(±14.7) and 59.5(±14.1) years, respectively. Both groups were similar with respective to body mass index. A majority of the cases in both groups involved posterior/posterolateral approach; 55.5% of patients in PT group and 50.9% in no-PT had 1 level lumbar fusion. Mean change (preoperative vs 1-year postoperative) in ODI between the two groups differed significantly (PT vs no-PT: 18.8±13.9 and 9.3±17.5; p=0.019). Similarly, mean change in VAS was significantly different between the two groups (PT vs. no-PT: 3.2±2.18 and 1.05±2.08; p=0.026). None of our PT patients reported any change in pre vs 1-year postoperative followup employment status (35% retired, 38% employed full-time, 11% unemployed and 16% homemaker). Ninety-eight percent of no-PT patients reported no change in employment status during the same timeframe (46% retired, 25% employed full-time, 13% unemployed and 15% homemaker). CONCLUSIONS PT group reported significant improvements in functional and pain scores than their counterparts. Post-lumbar fusion rehabilitation may benefit the majority of adult patients undergoing lumbar fusion surgery for a degenerative indication. Prospective studies with standardized PT approach, additional patients and greater statistical power are needed to further understand the effects of physical therapy on patients undergoing lumbar fusions for degenerative lumbar instability. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Fewer studies in the literature have examined the role of postoperative physical therapy (PT) after lumbar fusion. In the postoperative setting, much of the rehabilitation literature focuses on postdiscectomy patients. Evaluate and compare the changes in pain and functional scores between patients who completed physical therapy (PT) versus no-PT after their anterior or posterior 1-2 level lumbar fusions for degenerative lumbar instability. Our hypothesis was that the PT group may experience comparatively better functional and pain outcomes than their counterparts. Retrospective. A total of 123 patients with degenerative lumbar instability. Oswestry disability index (ODI) and visual analog scale (VAS). A database of patients undergoing 1-2 level lumbar fusion surgery for degenerative disease was assembled. Demographic and outcome scores such as oswestry disability index (ODI) and visual analog scale (VAS) in patients who participated in postoperative PT vs those that did not were compared. There were 72 and 51 patients in PT and no-PT that met the inclusion criteria, respectively. There were higher numbers of females (63.8%) in PT group. No-PT group had similar numbers of males and females. Mean ages for PT and no-PT groups were 61.4(±14.7) and 59.5(±14.1) years, respectively. Both groups were similar with respective to body mass index. A majority of the cases in both groups involved posterior/posterolateral approach; 55.5% of patients in PT group and 50.9% in no-PT had 1 level lumbar fusion. Mean change (preoperative vs 1-year postoperative) in ODI between the two groups differed significantly (PT vs no-PT: 18.8±13.9 and 9.3±17.5; p=0.019). Similarly, mean change in VAS was significantly different between the two groups (PT vs. no-PT: 3.2±2.18 and 1.05±2.08; p=0.026). None of our PT patients reported any change in pre vs 1-year postoperative followup employment status (35% retired, 38% employed full-time, 11% unemployed and 16% homemaker). Ninety-eight percent of no-PT patients reported no change in employment status during the same timeframe (46% retired, 25% employed full-time, 13% unemployed and 15% homemaker). PT group reported significant improvements in functional and pain scores than their counterparts. Post-lumbar fusion rehabilitation may benefit the majority of adult patients undergoing lumbar fusion surgery for a degenerative indication. Prospective studies with standardized PT approach, additional patients and greater statistical power are needed to further understand the effects of physical therapy on patients undergoing lumbar fusions for degenerative lumbar instability.

P146. The impact of race/ethnicity on perioperative outcome measures: a longitudinal analysis of patients undergoing lumbar fusion surgery in the United States

<h3>BACKGROUND CONTEXT</h3> Previous studies have described racial and ethnic disparities in outcomes after lumbar fusion surgery. It is unclear to what extent these disparities have changed over time among patients undergoing lumbar fusion surgery in the United States (US). <h3>PURPOSE</h3> Evaluate racial/ethnic disparities for lumbar fusion surgery outcomes as measured by length of hospital stay in days (LOS) and discharge disposition (DD). <h3>STUDY DESIGN/SETTING</h3> This retrospective study examined US discharge summaries compiled by the National Inpatient Sample from 2003-2018. <h3>PATIENT SAMPLE</h3> Discharge summaries representing 2,438,062 Black non-Hispanic, White non-Hispanic, and Hispanic adult inpatients with a diagnosis of lumbar stenosis, disc herniation/degeneration, spondylosis and/or spondylolisthesis who underwent a lumbar fusion were included. <h3>OUTCOME MEASURES</h3> The primary outcomes were LOS and DD for each hospitalization, stratified by race/ethnicity. DD was classified as ‘routine' (reference), or ‘non-routine' which included ‘Transfer to Short-term Hospital' (TSTH), ‘Transfer to Other [Facility]' (TOF) (including Skilled Nursing Facilities and Intermediate Care Facilities), and discharge to ‘Home Health Care' (HHC). <h3>METHODS</h3> A multivariable generalized linear model with a gamma distribution and a multinomial logistic regression model were utilized to measure the association between race/ethnicity and LOS/DD, respectively. Models were adjusted for gender, age, primary payor, zip code-specific income quartile, geographical region, Deyo-Charlson Comorbidity Index, year of the procedure, hospital bed size and location/setting of the procedure. To assess racial/ethnic disparities over time, an interaction term between race/ethnicity and year was introduced. Unstandardized coefficients (B), odds ratios (OR) and 95% confidence intervals (95% CI) are reported. <h3>RESULTS</h3> Mean LOS for White, Black, and Hispanic patients declined from 4.4, 4.8 and 4.6 days in 2003 to 3.7, 4.4 and 4.0 days in 2018, respectively. After adjustment for relevant covariates, Black (B:1.097; 95% CI:1.095-1.100) and Hispanic (B:1.056; 95% CI:1.053-1.059) patients had significantly longer LOS compared to White patients (Reference B:1.000) when analyzing the 16-year study period. When evaluating DD, non-routine discharges for White and Hispanic patients increased from 27%, 35% and 25% in 2003 to 39%, 54% and 43% in 2018, respectively. Black patients had increased odds of non-routine discharges, including TSTH (OR:2.029, 95% CI:1.895-2.172), TOF (OR:1.854, 95% CI:1.826-1.881) and discharge to HHC (OR:1.420, 95% CI:1.401-1.439) when compared to White patients (Reference OR:1.000). Similarly, Hispanic patients also experienced increased odds of TSTH (OR:1.213, 95% CI:1.100-1.337), TOF (OR:1.399, 95% CI:1.374-1.424), and discharge to HHC (OR:1.371, 95% CI:1.351-1.392) compared with White patients. Utilizing the interaction term between race/ethnicity and year, we identified that from 2009 to 2018 Black patients progressively experienced increasing odds of TOF (2009 OR:0.609, 95% CI:0.560-0.663; 2018 Reference OR:1.000) and discharge to HHC (2009 OR:0.630, 95% CI:0.585-0.679). <h3>CONCLUSIONS</h3> Significant racial/ethnic disparities in LOS persisted within the context of falling mean LOS for all racial/ethnic groups. The percentage of patients experiencing non-routine DD grew for all racial/ethnic groups over the study period, however, from 2009 to 2018 increases in non-routine DD for Black patients outpaced those of White patients, resulting in increased levels of disparities. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

43. Comparison of radiographic adjacent segment pathology at five years following minimally invasive compared to open lumbar 1- to 2-level fusion surgery

<h3>BACKGROUND CONTEXT</h3> Adjacent segment pathology remains a major cause of morbidity among patients receiving posterior lumbar instrumented fusion. Its occurrence is proposed to be secondary to the increased motion and biomechanical stresses from fused to unfused segment. Additionally, progressive degenerative processes in the spine can also be influenced by surgery-related factors that alter the spine biomechanics as a result of muscle destruction and facet joint violation. Controversy in the rates of radiographic adjacent segment pathology (RASP) after lumbar fusion surgery has stemmed by and large from variable reporting in the literature with short long-term follow-up periods and no comparison between muscle splitting minimally invasive (MIS) approach and posterior midline open fusions. We report a single-center cohort analysis of patients undergoing lumbar fusion surgery and describe the rate of RASP between patients undergoing minimally invasive tubular approach (MIS) vs open posterior fusion technique. <h3>PURPOSE</h3> The objective of this study is to evaluate the rate of RASP between MIS and open lumbar fusion surgery within 5-year follow-up period. <h3>STUDY DESIGN/SETTING</h3> Observational study. <h3>PATIENT SAMPLE</h3> Adults with degenerative lumbar disease who underwent 1- to 2-level open and MIS fusion at our institution from January 2006 to December 2016. <h3>OUTCOME MEASURES</h3> Rate of radiographic adjacent segment pathology. <h3>METHODS</h3> The authors conducted a retrospective chart review of patients diagnosed with degenerative lumbar disease who had undergone 1- to 2-level fusion between January 2006 to December 2016. Cases with upright lumbar radiographs were included in this sub-analysis. The patients were divided into an MIS fusion group and an open surgery group based on the surgical technique performed. The two groups were compared for baseline demographic features, surgical variables and diagnosis at index surgery. Adjacent segment pathology was evaluated using radiographs taken at the 5-year follow-up period. RASP is defined by the presence of any one or combination of (1) disc degeneration (height loss), (2) development of spondylolisthesis and (3) coronal deformity/lateral listhesis. Analysis was confined to rates of development of RASP with no attempt of correlating with symptomatic adjacent segment pathology. Logistic regression analysis was performed to assess relationship of demographic factors with development of RASP <h3>RESULTS</h3> A total of 165 patients were included: MIS (n = 73) and (n = 92) open. There was no significant difference between two groups in age, sex, diagnosis at index surgery, level of fusion and baseline RASP. Fusion involved one level in 72.7 % of cases and 2 levels in 27.3%. The overall incidence of RASP was 41.2%, with incidence of 36.9% in MIS group and 44.6% in the open surgery group, showing no significant difference between the two groups (p = 0.5246). In those with RASP, the most common radiographic finding was disc degeneration (height loss) for both cohorts (100% vs 87.8%, p = 0.264) with the majority occurring cephalad to previous instrumentation. Logistic regression analysis did not show significant correlation between sex, age, index diagnosis, presence of baseline RASP and the prevalence of RASP at 5 years. <h3>CONCLUSIONS</h3> The prevalence of radiographic adjacent segment pathology did not statistically differ between MIS and open lumbar fusion surgery at minimum of 5-year follow-up. Baseline demographics or primary pathoanatomical diagnosis did not correlate to the presence of RASP 5 years following surgery in either group. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

The effect of age on psoas and paraspinal muscle morphology in patients undergoing posterior lumbar fusion surgery.

The aim of this study was to determine the effect of age on the psoas and posterior paraspinal muscles (PPM; multifidus muscle and erector spinae) and to evaluate potential sex-related differences. MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA), the fat area (FAT) and the proportion of intramuscular fat (FI) were conducted on patients undergoing lumbar fusion surgery between 2014 and 2021. The regions of interest were the psoas muscle and the PPM at the superior endplate of L4. The left and right sides of the muscle groups were summarized and normalized by the patient's height (cm2/m2). The relationships between age and muscular parameters were analyzed stratified by sex. A total of 195 patients (57.9%female) with a median age of 64.2years and a body mass index of 28.3kg/m2 were analyzed. The CSAPsoas was 7.7 cm2/m2 and differed significantly between females and males (p < 0.001); likewise, the fCSAPsoas differed significantly between the sexes. The CSAPPM was 18.8 cm2/m2 with no sex-specific differences. Significant differences were found in the FIPPM (males: 41.1% vs. females: 47.9%; p < 0.001), but not in the FIPsoas (males: 3.7% vs. females: 4.5%; p = 0.276). Considering the effect of age on FI, a significant positive correlation was observed for the PPMs for both sexes. Only in women, there was a negative correlation between age and CSAPsoas (ρ = - 0.248; p = 0.008), FATPsoas (ρ = - 0.421; p < 0.001) and FIPsoas (ρ = - 0.371; p < 0.001). This study demonstrated sex-specific differences in spinal muscle morphology in relation to patient age. With increasing age there was a decrease in FIPsoas in women only, unlike in the PPMs in which there was increased FI that was significantly higher in women compared to men.

Predicting prolonged postoperative length of stay risk in patients undergoing lumbar fusion surgery: Development and assessment of a novel predictive nomogram.

ObjectiveThe purpose of this study was to develop and internally validate a prediction nomogram model in patients undergoing lumbar fusion surgery.MethodsA total of 310 patients undergoing lumbar fusion surgery were reviewed, and the median and quartile interval were used to describe postoperative length of stay (PLOS). Patients with PLOS > P75 were defined as prolonged PLOS. The least absolute shrinkage and selection operator (LASSO) regression was used to filter variables for building the prolonged PLOS risk model. Multivariable logistic regression analysis was applied to build a predictive model using the variables selected in the LASSO regression model. The area under the ROC curve (AUC) of the predicting model was calculated and significant test was performed. The Kappa consistency test between the predictive model and the actual diagnosis was performed. Discrimination, calibration, and the clinical usefulness of the predicting model were assessed using the C-index, calibration plot, and decision curve analysis. Internal validation was assessed using the bootstrapping validation.ResultsAccording to the interquartile range of PLOS in a total of 310 patients, the PLOS of 235 patients was ≤P75 (7 days) (normal PLOS), and the PLOS of 75 patients was > P75 (prolonged PLOS). The LASSO selected predictors that were used to build the prediction nomogram included BMI, diabetes, hypertension, duration of surgery, duration of anesthesia, anesthesia type, intraoperative blood loss, sufentanil for postoperative analgesia, and postoperative complication. The model displayed good discrimination with an AUC value of 0.807 (95% CI: 0.758–0.849, P < 0.001), a Kappa value of 0.5186 (cutoff value, 0.2445, P < 0.001), and good calibration. A high C-index value of 0.776 could still be reached in the interval validation. Decision curve analysis showed that the prolonged PLOS nomogram was clinically useful when intervention was decided at the prolonged PLOS possibility threshold of 3%.ConclusionsThis study developed a novel nomogram with a relatively good accuracy to help clinicians access the risk of prolonged PLOS in lumbar fusion surgery patients. By an estimate of individual risk, surgeons and anesthesiologists may shorten PLOS and accelerate postoperative recovery of lumbar fusion surgery through more accurate individualized treatment.

Clinical Implication of the Acumen Hypotension Prediction Index for Reducing Intraoperative Haemorrhage in Patients Undergoing Lumbar Spinal Fusion Surgery: A Prospective Randomised Controlled Single-Blinded Trial.

We investigated the clinical implication of the Hypotension Prediction Index (HPI) in decreasing amount of surgical haemorrhage and requirements of blood transfusion compared to the conventional method (with vs. without HPI monitoring). A prospective, randomised controlled-trial of 19- to 73-year-old patients (n = 76) undergoing elective lumbar spinal fusion surgery was performed. According to the exclusion criteria, the patients were divided into the non-HPI (n = 33) and HPI (n = 35) groups. The targeted-induced hypotension systolic blood pressure was 80–100 mmHg (in both groups), with HPI > 85 (in the HPI group). Intraoperative bleeding was lower in the HPI group (299.3 ± 219.8 mL) than in the non-HPI group (532 ± 232.68 mL) (p = 0.001). The non-HPI group had a lower level of haemoglobin at the end of the surgery with a larger decline in levels. The incidence of postoperative transfusion of red blood cells was higher in the non-HPI group than in the HPI group (9 (27.3%) vs. 1 (2.9%)). The use of HPI monitoring may play a role in providing timely haemodynamic information that leads to improving the quality of induced hypotension care and to ameliorate intraoperative surgical blood loss and postoperative demand for blood transfusion in patients undergoing lumbar fusion surgery.

Paraspinal musculature impairment is associated with spinopelvic and spinal malalignment in patients undergoing lumbar fusion surgery

BACKGROUND CONTEXTThe 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. PURPOSEThis 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/SETTINGRetrospective cross-sectional study. PATIENT SAMPLEPatients 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 MEASURESPPM 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). METHODSA 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 (cm2/m2). 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. RESULTSA 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/m2. Significant positive correlations were observed between PT (ρ=0.327), SVA (ρ=0.256) and PI (ρ=0.202) and the FIPPM. Significant negative correlations were detected for the PT and the fCSAPPM (ρ=-0.202) and PT and the fCSAPsoas (ρ=-0.191). Furthermore, a negative correlation was seen for PI and SVA and FIPsoas. 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 FIPPM (corrected R2=0.393) as independent variables. CONCLUSIONSThis 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 FIPPM, 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.

Rehabilitation to improve outcomes of lumbar fusion surgery: a systematic review with meta-analysis.

To evaluate the effectiveness of rehabilitation strategies on disability, pain, pain-related fear, and return-to-work in patients undergoing lumbar fusion surgery for degenerative conditions or adult isthmic spondylolisthesis. Six electronic databases were systematically searched for randomized controlled trials (RCTs) evaluating the effect of rehabilitation (unimodal or multimodal). The estimated effect size was calculated for interventions with homogeneous content using a random-effects model. Certainty of evidence was assessed by GRADE. In total, 18 RCTs, including 1402 unique patients, compared specific rehabilitation to other rehabilitation strategies or usual care. Most described indications were degenerative disc disease and spondylolisthesis. All rehabilitation interventions were delivered in the postoperative period, and six of them also included a preoperative component. Intervention dose and intensity varied between studies (ranging from one session to daily sessions for one month). Usual care consisted mostly of information and postoperative mobilization. At short term, low quality of evidence shows that exercise therapy was more effective for reducing disability and pain than usual care (standardized mean difference [95% CI]: -0.41 [-0.71; -0.10] and -0.36 [-0.65; -0.08], four and five studies, respectively). Multimodal rehabilitation consisted mostly of exercise therapy combined with cognitive behavioral training, and was more effective in reducing disability and pain-related fear than exercise therapy alone (-0.31 [-0.49; -0.13] and -0.64 [-1.11; -0.17], six and four studies, respectively). Effects disappeared beyond one year. Rehabilitation showed a positive tendency towards a higher return-to-work rate (pooled relative risk [95% CI]: 1.30 [0.99; 1.69], four studies). There is low-quality evidence showing that both exercise therapy and multimodal rehabilitation are effective for improving outcomes up to six months after lumbar fusion, with multimodal rehabilitation providing additional benefits over exercise alone in reducing disability and pain-related fear. Additional high-quality studies are needed to demonstrate the effectiveness of rehabilitation strategies in the long term and for work-related outcomes.

Comparison of Operative Time and Blood Loss With the FFX® Device Versus Pedicle Screw Fixation During Surgery for Lumbar Spinal Stenosis: A Retrospective Cohort Study.

BackgroundPedicle screw (PS) placement can be associated with soft tissue damage and blood loss. The study objective was to evaluate differences in operative time and blood loss between PS fixation and an implantable facet fusion device in patients undergoing lumbar fusion surgery.Materials and methodsA retrospective analysis was performed on patients undergoing lumbar fusion surgery with PS fixation or the lumbar Facet FiXation (FFX) device. Procedures were performed by the same surgeon at a single institution. The PS group included patients from 2016 and the FFX group included patients from 2018. Variables including age, sex, levels operated on, operative time, and operative blood loss were collected.ResultsA total of 70 patients were included in the study. Twenty-eight in the PS arm and 42 in the FFX arm. The PS group had a mean age of 67.5 ± 9.3 years compared to 70.4 ± 11.5 years for the FFX group. The PS group had a higher percentage of females (57.1%) versus the FFX group (31.0%); p = 0.025. Mean number of levels operated on were similar between the PS and FFX groups (2.3 ± 1 .1 vs. 2.2 ± 1.0, respectively; p = 0.89). Mean operative time was significantly longer for the PS group versus the FFX group (152.5 ± 39.4 vs. 99.4 ± 44.0 minutes; p < 0.001). Mean operative blood loss was significantly greater for the PS group versus the FFX group (446.5 ± 272.0 vs. 251.0 ± 315.9 mL; p < 0.01). Differences were independent of the number of levels operated on.ConclusionPlacement of the FFX device is associated with a significant reduction in operative time and blood loss compared to PS fixation in patients undergoing spinal fusion surgery.

The association between paraspinal muscle parameters and vertebral pedicle microstructure in patients undergoing lumbar fusion surgery

The association between paraspinal muscle parameters and vertebral pedicle microstructure in patients undergoing lumbar fusion surgery