Effect of body mass index on patient outcomes of surgical intervention for the lumbar spine

Obesity is an Independent Risk Factor for Postoperative Pulmonary Embolism after Anterior Cervical Discectomy and Fusion

BACKGROUND

Over the past decade, the prevalence of obesity has risen in the United States, in parallel with the demand for anterior cervical discectomy with fusion (ACDF). Prior studies have evaluated the role of obesity classes in cervical spine surgery in smaller patient populations. We aimed to evaluate any potential correlation to a national population sample by utilizing a large multicenter database.

PURPOSE

The purpose of this study was to analyze obesity level's influence on peri-operative complication rates in patients undergoing ACDF.

STUDY DESIGN/SETTING

A retrospective cohort, large multicenter database study.

PATIENT SAMPLE

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried to identify patients who had undergone an elective ACDF procedure between 2011 and 2020 using Current Procedural Terminology (CPT) code 22551.

OUTCOME MEASURES

Medical and surgical complications within thirty days of operation.

METHODS

Patients were categorized into four BMI groups: non-obese (BMI 18.5-29.9 kg/m2), obese class I (BMI 30-34.9 kg/m2), obese class II (BMI 35-39.9 kg/m2), and obese class III (BMI ≥40 kg/m2). A univariate analysis conducted for demographic variables and pre-operative comorbidities identified age, sex, race, smoking status, hypertension requiring medication, diabetes, history of congestive heart failure, history of bleeding disorder, and chronic obstructive pulmonary disease as risk factors. Chi-square test was used to compare incidence of complications among groups. A multivariable logistic regression analysis was subsequently performed to adjust for these preoperative risk factors and compare obesity classes I-III to non-obese patients.

RESULTS

64,718 patients were identified of whom 33,365 were non-obese, 17,190 were obese class I, 8,608 were obese class II, and 5,555 were obese class III. Obese classes I-III patients had a higher incidence of surgical site infections (0. 33%, 0.36%, 0.41%, vs 0.24%, p = 0.039) and pulmonary embolism (PE) (0.25%, 0.31, 0.29 versus 0.15%, p = 0.003). Obese classes I-III had a lower incidence of blood transfusion (0.23%, 0.17%, 0.27% vs 0.4%, p < 0.001) obese class I, obese class II, and obese class III independently increased the risk for PE (OR: 1.716, 95% CI (1.129-2.599); OR: 2.213, 95% CI (1.349-2.3.559); OR: 2.207, 95% CI (1.190-3.892), respectively).

CONCLUSIONS

Risk for post-operative PEs after an ACDF was significantly higher for obese classes I-III compared to non-obese patients. These findings may further support the use of additional prophylaxis measures and precaution in the perioperative setting.

Comparison of functional outcomes and patient satisfaction in patients with lumbar canal stenosis with and without concomitant obesity following lumbar decompression surgery and their correlation with BMI

BACKGROUND

Obesity is an important predictor of development of Lumbar canal stenosis (LCS) and its symptoms. LCS further restricts the mobility of the patient and a vicious cycle develops. The operative decision on patients with LCS and obesity is a matter of debate. Hence, we attempted to compare changes in body mass index and patient satisfaction in patients with LCS with and without concomitant obesity, undergoing spinal decompression surgery.

METHODS

Patients undergoing decompression for LCS between 1st June 2019 to 31st May 2020 were included. Baseline characteristics including age, sex, co-morbidities, BMI, self-recorded maximal walking distance (SR-MWD) and Oswestry disability index score (ODI) were recorded. All patients were followed up prospectively at 1 year post surgery. Satisfaction was recorded on a five-point Likert scale. Participants were classified into non obesity (group 1) and obesity (group 2) groups according to JAPI and WHO classification and compared.

RESULTS

55 patients met the inclusion criteria, 23 in group 1 and 32 in group 2. Group 2 showed a mean decrease in BMI of 0.95 ± 1.32 kg/m2 while other group had an increase of 0.14 ± 1.31 kg/m2 (p = 0.021). Significant weight change was seen in 31.3 % group 2 vs 8.7 % group 1 patients which was significant (p = 0.046). Pre operative BMI positively correlated with change in BMI after surgery (r = 0.406, p = 0.001) and with percentage weight reduction (r = 0.321, p = 0.017). Both the groups were comparable in improvement in ODI and SR-MWD scores and patient satisfaction.

CONCLUSION

Patients with obesity achieve significant reduction in weight and BMI following decompression surgery for LCS. It will further prevent other health conditions attributed to obesity. Both the groups were comparable in ODI, SR-MWD and satisfactory outcome following surgery. Hence obesity should not be a deterring factor for surgical consideration for patients with lumbar canal stenosis.

Characterizing utilization patterns and reoperation risk factors of interspinous process devices: analysis of a national claims database

INTRODUCTION

Interspinous process devices (IPDs) were developed as minimally invasive alternatives to open decompression surgery for spinal stenosis. However, given high treatment failure and reoperation rates, there has been minimal adoption by spine surgeons. This study leveraged a national claims database to characterize national IPD usage patterns and postoperative outcomes after IPD implantation.

METHOD

Using the PearlDiver database, we identified all patients who underwent 1- or 2-level IPD implantation between 2010 and 2018. Univariate and multivariable logistic regression was performed to identify predictors of the number of IPD levels implanted and reoperation up to 3 years after the index surgery. Right-censored Kaplan-Meier curves were plotted for duration of reoperation-free survival and compared with log-rank tests.

RESULTS

Patients (n = 4865) received 1-level (n = 3246) or 2-level (n = 1619) IPDs. Patients who were older (adjusted odds ratio [aOR] 1.02, 95% confidence interval [CI] 1.01-1.03, P < .001), male (aOR 1.31, 95% CI 116-1.50, P < .001), and obese (aOR 1.19, 95% CI 1.05-1.36, P < .01) were significantly more likely to receive a 2-level IPD than to receive a 1-level IPD. The 3-year reoperation rate was 9.3% of patients when mortality was accounted for during the follow-up period. Older age decreased (aOR 0.97, 95% CI 0.97-0.99, P = .0039) likelihood of reoperation, whereas 1-level IPD (aOR 1.37, 95% CI 1.01-1.89, P = .048), Charlson Comorbidity Index (aOR 1.07, 95% CI 1.01-1.14, P = .018), and performing concomitant open decompression increased the likelihood of reoperation (aOR 1.68, 95% CI 1.35-2.09, P = .0014).

CONCLUSION

Compared with 1-level IPDs, 2-level IPDs were implanted more frequently in older, male, and obese patients. The 3-year reoperation rate was 9.3%. Concomitant open decompression with IPD placement was identified as a significant risk factor for subsequent reoperation and warrants future investigation.

The impact of being overweight or obese on 12 month clinical recovery in patients following lumbar microdiscectomy for radiculopathy

BACKGROUND CONTEXT

The proportion of patients who undergo lumbar microdiscectomy due to lumbar radiculopathy who are also overweight or obese is high. However, whether high body mass index (BMI) affects clinical outcomes is not well-studied.

PURPOSE

To investigate the difference in the clinical course between normal weight, overweight, and obese patients with radiculopathy who underwent lumbar microdiscectomy followed by physical therapy and to evaluate whether high BMI is associated with poor recovery.

STUDY DESIGN/SETTING

A prospective cohort study with a 12-month follow-up was conducted in a multidisciplinary clinic.

PATIENT SAMPLE

We included 583 patients (median [IQR] age: 45 [35-52] years; 41% female) with clinical signs and symptoms of lumbar radiculopathy, consistent with magnetic resonance imaging findings, who underwent microdiscectomy followed by postoperative physical therapy.

OUTCOME MEASURES

Outcomes were leg pain and back pain intensity measured with a visual analogue scale, disability measured with the Roland Morris Disability Questionnaire at 3 and 12-month follow-ups, and complications.

METHODS

Patients were classified as being normal weight (46.9%), overweight (38.4%), or obese (14.7%). A linear mixed-effects model was used to assess the difference in the clinical course of pain and disability between the three BMI categories. The association between BMI and outcomes was evaluated using univariable and multivariable logistic regression analyses.

RESULTS

All three patient groups experienced a significant improvement in leg pain, back pain, and disability over 3 and 12-month follow-up. Patients who were overweight, obese, or normal weight experienced comparable leg pain (p=.14) and disability (p=.06) over the clinical course (p=.14); however, obese patients experienced higher back pain (MD=-6.81 [95%CI: -13.50 to -0.14]; p=.03). The difference in back pain scores was not clinically relevant.

CONCLUSIONS

In the first year following lumbar microdiscectomy, patients demonstrated clinical improvements and complications that were unrelated to their preoperative BMI.

Impact of obesity on adult spinal deformity (ASD) long-segment spinal fusion radiographic and clinical outcomes

STUDY DESIGN

Retrospective chart review of patients receiving long-segment fusion during a five-year period.

OBJECTIVE

To determine whether obese patients receive comparable benefits when receiving long-segment fusion compared to non-obese patients and to identify factors that may predict hardware failure and post-surgical complications among obese patients.

METHODS

Demographic, spinopelvic radiographic, patient-reported outcome measures (PROMs), and complications data was retrospectively collected from 120 patients who underwent long-segment fusion during a five-year period at one tertiary care medical center. Radiographic measurements were pelvic incidence, pelvic tilt (PT), lumbar lordosis, L4-S1 lordosis, thoracic kyphosis, sagittal vertical axis, PI-LL mismatch, and proximal junction cobb angle at upper instrumented vertebrae + 2 (UIV+2). PROMs were Oswestry disability index, numeric rating scale (NRS) Back Pain, NRS Leg Pain, RAND SF-36 pain, and RAND SF-36 physical functioning. Included patients were adults and had at least 2-years of postoperative follow-up. Descriptive and multivariate statistical analysis was performed with α = 0.05.

RESULTS

Patients with a BMI ≥ 30 (n=63) and patients with a BMI < 30 (n=57) demonstrated comparable improvements (P>0.05) for all spinopelvic radiographic measurements and PROMs. Each cohort demonstrated significant improvements from pre-assessment to post-assessment on nearly all spinopelvic radiographic measurements and PROMs (P<0.05), except PT and L4-S1 lordosis where neither group improved (p=0.95 and 0.58 for PT and P=0.23 and 0.11 for L4-S1 lordosis fornon-obese and obese cohorts respectively) and SF-36 physical functioning where the non-obese cohort not statistically improve (P=0.08). Patients with a BMI ≥ 30 demonstrated an increased incidence of cardiovascular complications (P=0.0293), acute kidney injury (P=0.0241), rod fractures (P=0.0293), and reoperations (P=0.0241) when compared to patients with a BMI < 30.

CONCLUSION

This study adds to a growing body of evidence linking demographic factors with risks of hardware failure. Further, this data challenges the assumption that obese patients may not receive sufficient benefit to be long-segment surgical candidates. However, given their elevated risk for post-operative and delayed hardware complications, obese patients should be appropriately counseling before undergoing surgery.

Development and validation of a novel thoracic spinal stenosis surgical invasiveness index: a single-center study based on 989 patients

BACKGROUND CONTEXT

Surgical invasiveness indices have been established for general spine surgery (surgical invasiveness index [SII]), spine deformity, and metastatic spine tumors; however, a specific index for thoracic spinal stenosis (TSS) has not been developed.

PURPOSE

To develop and validate a novel invasiveness index, incorporating TSS-specific factors for open posterior TSS surgery, which may facilitate the prediction of operative duration and intraoperative blood loss, and the stratification of surgical risk.

STUDY DESIGN

A retrospective observational study.

PATIENT SAMPLE

Overall, 989 patients who underwent open posterior TSS surgeries at our institution during the past 5 years were included.

OUTCOME MEASURES

The operation duration, estimated blood loss, transfusion status, major surgical complications, length of hospital stay, and medical expenses.

METHODS

We retrospectively analyzed the data of 989 consecutive patients who underwent posterior surgery for TSS between March 2017 and February 2022. Among them, 70% (n=692) were randomly placed in a training cohort, and the remaining 30% (n=297) automatically constituted the validation cohort. Multivariate linear regression models of operative time and log-transformed estimated blood loss were created using TSS-specific factors. Beta coefficients derived from these models were used to construct a TSS invasiveness index (TII). The ability of the TII to predict surgical invasiveness was compared with that of the SII and assessed in a validation cohort.

RESULTS

The TII was more strongly correlated with operative time and estimated blood loss (p<.05) and explained more variability in operative time and estimated blood loss than the SII (p<.05). The TII explained 64.2% of operative time and 34.6% of estimated blood loss variation, whereas the SII explained 38.7% and 22.5%, respectively. In further verification, the TII was more strongly associated with transfusion rate, drainage time, and length of hospital stay than SII (p<.05).

CONCLUSIONS

By incorporating TSS-specific components, the newly developed TII more accurately predicts the invasiveness of open posterior TSS surgery than the previous index.

Marijuana Use is Not a Contraindication for Tranexamic Acid Utilization in Lumbar Spine Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The purpose of this study was to evaluate safety in lumbar spinal fusion with tranexamic acid (TXA) utilization in patients using marijuana.

METHODS

This was a retrospective cohort study involving a single surgeon's cases of 1 to 4 level lumbar fusion procedures. Two hundred and ninety-four patients were followed for ninety days post-operatively. Consecutive patients were self-reported for daily marijuana use (n = 146) and compared to a similar cohort of patients who denied usage of marijuana (n = 146). Outcomes were collected, which included length of stay (LOS), estimated blood loss (EBL), post-operative myocardial infarction, seizures, deep venous thrombosis, pulmonary embolus, death, readmission, need for further surgery, infection, anaphylaxis, acute renal injury, and need for blood product transfusion.

RESULTS

Patients in the marijuana usage cohort had similar age (58.9 years ±12.9 vs 58.7 years ±14.8, P = .903) and distribution of levels fused (P = .431) compared to the non-usage cohort. Thromboembolic events were rare in both groups (marijuana usage: 1 vs non-usage: 2). Compared to the non-usage cohort, the marijuana usage cohort had a similar average EBL (329.9 ± 298.5 mL vs 374.5 ± 363.8 mL; P = .254). Multivariate regression modeling demonstrated that neither EBL (OR 1.27, 95% CI 0.64-2.49) nor need for transfusion (OR 1.56, 95% CI 0.43-5.72) varied between cohorts. The non-usage cohort had twice the risk of prolonged LOS compared to the marijuana usage cohort (OR 2.05, 95% CI 1.15-3.63).

CONCLUSION

Marijuana use should not be considered a contraindication for TXA utilization in lumbar spine surgery.

Impact of body mass index on outcomes after lumbar spine surgery

The impact of body mass index (BMI) on outcomes after lumbar spine surgery is currently unknown. Previous studies have reported conflicting evidence for patients with high BMI, while little research has been conducted on outcomes for underweight patients. This study aims to examine the impact of BMI on outcomes after lumbar spine surgery. This prospective cohort study enrolled 5622 patients; of which, 194, 5027, and 401 were in the low (< 18.5 kg/m²), normal (18.5-30), and high (≥ 30) BMI groups, respectively. Pain was assessed via the numerical pain rating scale (NPRS) for the lower back, buttock, leg, and plantar area. Quality of life was assessed via the EuroQol 5 Dimension (EQ-5D) and Oswestry Disability Index (ODI). Inverse probability weighting with propensity scores was used to adjust patient demographics and clinical characteristics between the groups. After adjustment, the 1-year postoperative scores differed significantly between groups in terms of leg pain. The proportion of patients who achieved a 50% decrease in postoperative NPRS score for leg pain was also significantly different. Obese patients reported less improvement in leg pain after lumbar spine surgery. The outcomes of patients with low BMI were not inferior to those of patients with normal BMI.

Body Mass Index and Risk of Complications After Posterior Lumbar Spine Fusion: A Matched Cohort Analysis Investigating Underweight and Obese Patients

OBJECTIVE

Previous studies have demonstrated that obesity is associated with increased complications after lumbar fusion. However, there are little published data on the effect of being underweight on lumbar fusion outcomes. The purpose of this study was to elucidate the effect of being underweight versus obese on outcomes after lumbar spinal fusion.

METHODS

Lumbar spinal fusion patients were identified through the PearlDiver Mariner database between 2010 and 2020. Study groups were created using International Classification of Diseases codes to identify preoperative body mass index (BMI) category as morbid obesity (BMI > 40), obesity (BMI 30 to 40), normal BMI (BMI 20 to 30), and underweight (BMI < 20) cohorts. Complications that occurred within 1 year postoperatively in this study and matched control groups were then isolated. Statistical analyses were conducted using the Pearson chi square method.

RESULTS

A total of 62,616 patients were identified in this analysis. This included 1,258 underweight patients (4.0%), 17,996 obese patients (57.5%), and 12,054 morbidly obese patients (38.5%). The number of patients to experience any postoperative complication was 766 (60.9%), 9,440 (52.4%), and 6,982 (57.9%) for the underweight, obese, and morbidly obese cohorts, respectively. Underweight patients showed an increased likelihood of complications related to instrumentation (odds ratio [OR] 1.85, P = 0.0237), revision fusion (OR 1.34, P = 0.04061), pulmonary complications (OR 1.43, P < 0.001), and sepsis (OR 1.91, P < 0.001). Obese patients with BMI 30 to 40 showed increased odds of the following complications: hemorrhages and hematomas (OR 1.20, P = 0.02634), surgical site complications (OR 1.27, P < 0.001), thromboembolism (OR 1.78, P < 0.001), and urinary complications (OR 1.08, P < 0.001). Morbidly obese patients with BMI > 40 showed increased odds of all complications analyzed in this study.

CONCLUSION

This investigation indicates that both underweight and obese patients are at elevated risk of complications after lumbar fusion. Similar to obese patients, underweight patients may benefit from preoperative optimization by nutrition counseling to avoid potential complications.

LEVEL OF EVIDENCE

III.

Risk factors for extended length of stay and non-home discharge in adults treated with multi-level fusion for lumbar degenerative pathology and deformity

PURPOSE

To identify independent risk factors, including the Risk Assessment and Prediction Tool (RAPT) score, associated with extended length of stay (eLOS) and non-home discharge following elective multi-level instrumented spine fusion operations for diagnosis of adult spinal deformity (ASD) and lumbar degenerative pathology.

METHODS

Adults who underwent multi-level ([Formula: see text] segments) instrumented spine fusions for ASD and lumbar degenerative pathology at a single institution (2016-2021) were reviewed. Presence of a pre-operative RAPT score was used as an inclusion criterion. Excluded were patients who underwent non-elective operations, revisions, operations for trauma, malignancy, and/or infections. Outcomes were eLOS (> 7 days) and discharge location (home vs. non-home). Predictor variables included demographics, comorbidities, operative information, Surgical Invasiveness Index (SII), and RAPT score. Fisher's exact test was used for univariate analysis, and significant variables were implemented in multivariate binary logistic regression, with generation of 95% percent confidence intervals (CI), odds ratios (OR), and p-values.

RESULTS

Included for analysis were 355 patients. Post-operatively, 36.6% (n = 130) had eLOS and 53.2% (n = 189) had a non-home discharge. Risk factors significant for a non-home discharge were older age (> 70 years), SII > 36, pre-op RAPT < 10, DMII, diagnosis of depression or anxiety, and eLOS. Risk factors significant for an eLOS were SII > 20, RAPT < 6, and an ASA score of 3.

CONCLUSION

The RAPT score and SII were most important significant predictors of eLOS and non-home discharges following multi-level instrumented fusions for lumbar spinal pathology and deformity. Preoperative optimization of the RAPT's individual components may provide a useful strategy for decreasing LOS and modifying discharge disposition.

Risk Assessment of Anterior Lumbar Interbody Fusion Access in Degenerative Spinal Conditions

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

Develop an evidence-based preoperative risk assessment scoring system for patients undergoing anterior lumbar interbody fusion (ALIF).

SUMMARY OF BACKGROUND DATA

ALIF may hold advantages over other fusion techniques in sagittal restoration and fusion rates, though it introduces unique risks to vascular and abdominal structures and thus possibly increased risk of operative morbidity.

METHODS

Primary, 1 or 2-level ALIFs were identified in a surgical registry. Baseline characteristics were recorded. Axial magnetic resonance imagings at L4-L5 and L5-S1 were reviewed for vascular confluence/bifurcation or anomalous structures, and measured for operative window size/slope. To assess favorable outcomes, a clinical grade was calculated: (clinical grade=blood loss×operative duration), higher value indicating poorer outcome. To establish a risk scoring system, a base risk score algorithm was established and stratified into 5 categories: high, high to intermediate, intermediate, intermediate to low, and low. Modifiers to base risk score included age, body mass index, operative level, history of bone morphogenic protein use, calcified vasculature, spondylolisthesis grade, working window size and slope, and abnormal vasculature. Modifiers were weighted for contribution to surgical risk. A total risk score was calculated and evaluated for strength of association with clinical outcome grades by Pearson correlation coefficient.

RESULTS

A total of 65 patients were included. Mean clinical outcome grade was 5.6, mean total risk score 21.3±21.5. Multilevel procedures (L4-S1) mean total risk score was 57.3±7.8. L4-L5 mean total risk score was 23.6±5.2; L5-S1 mean total risk score 8.3±6.6. Correlation analysis demonstrated a significant and strong relationship (| r |=0.753; P <0.001) between total risk scores and clinical outcome grades.

CONCLUSION

Calculated ALIF risk scores significantly correlated with operative duration and blood loss. This scoring system represents a potential framework to facilitate clinical decision-making and risk assessment for potential ALIF candidates with degenerative spinal pathologies.

Obesity and Spine Surgery: A Qualitative Review About Outcomes and Complications. Is It Time for New Perspectives on Future Researches?

STUDY DESIGN

Literature review.

OBJECTIVES

An increasing number of obese patients requires operative care for degenerative spinal disorders. The aim of this review is to analyze the available evidence regarding the role of obesity on outcomes after spine surgery. Peri-operative complications and clinical results are evaluated for both cervical and lumbar surgery. Furthermore, the contribution of MIS techniques for lumbar surgery to play a role in reducing risks has been analyzed.

METHODS

Only articles published in English in the last 10 years were reviewed. Inclusion criteria of the references were based on the scope of this review, according to PRISMA guidelines. Moreover, only paper analyzing obesity-related complications in spine surgery have been selected and thoroughly reviewed. Each article was classified according to its rating of evidence using the Sacket Grading System.

RESULTS

A total number of 1636 articles were found, but only 130 of them were considered to be relevant after thorough evaluation and according to PRISMA checklist. The majority of the included papers were classified according to the Sacket Grading System as Level 2 (Retrospective Studies).

CONCLUSION

Evidence suggest that obese patients could benefit from spine surgery and outcomes be satisfactory. A higher rate of peri-operative complications is reported among obese patients, especially in posterior approaches. The use of MIS techniques plays a key role in order to reduce surgical risks. Further studies should evaluate the role of multidisciplinary counseling between spine surgeons, nutritionists and bariatric surgeons, in order to plan proper weight loss before elective spine surgery.

Comparison of Perioperative and Postoperative Outcomes of Minimally Invasive and Open TLIF in Obese Patients: A Systematic Review and Meta‑Analysis

PURPOSE

Previous studies have demonstrated that minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) is comparable to the open approach in terms of efficacy and safety. However, few comparative studies of surgical procedures in patients with obesity show that they may react differently to open-TLIF (O-TLIF) and MI-LTIF approaches.

PATIENTS AND METHODS

The main indicators were complications, visual analog scale (VAS) score, and Oswestry Disability Index (ODI) score, and secondary indicators were operative time, blood loss, and hospital stay.

RESULTS

No significant differences in the VAS and ODI scores for back pain at the last follow-up and wound infection rates were observed between the two groups. Dural tear incidence and complication rate were significantly lower in the MI-TLIF group than that in the O-TLIF group (P = 0.002 and 0.001, respectively). No significant difference in operative time was found between the two groups. There was less blood loss and shorter hospital stay (P = 0.001 and 0.002, respectively) in the MI-TLIF group than that in the O-TLIF group.

CONCLUSION

Compared with O-TLIF, MI-TLIF is an effective and safe surgical option for patients with obesity, which resulted in similar improvements in pain and functional disability, as well as a lower complication rate.

Obesity and perioperative outcomes in older surgical patients undergoing elective spine and major arthroplasty surgery

STUDY OBJECTIVE

To determine whether obesity status is associated with perioperative complications, discharge outcomes and hospital length of stay in older surgical patients.

DESIGN

Secondary analysis of five independent study cohorts (N = 1262).

SETTING

An academic medical center between 2001 and 2017 in the United States.

PATIENTS

Patients aged 65 years or older who were scheduled to undergo elective spine, knee, or hip surgery with an expected hospital stay of at least 2 days.

MEASUREMENTS

Body mass index (BMI) was stratified as nonobese (BMI ≤ 30 kg/m2), obesity class 1 (30 kg/m2 ≤ BMI < 35 kg/m2) or obesity class 2-3 (BMI ≥ 35 kg/m2). Primary outcomes included predefined intraoperative and postoperative complications, hospital length of stay (LOS), and discharge location. Univariate and multivariate logistic regression was performed.

MAIN RESULTS

Obesity status was not associated with intraoperative adverse events. However, obesity class 2-3 significantly increased the risk for postoperative complications (IRR 1.43, 95% CI 1.03-1.95, P = 0.03), hospital LOS (IRR 1.13, 95% CI 1.02-1.25, P = 0.02) and non-home discharge destination (OR 1.95, 95% CI 1.35-2.81, P < 0.001) after accounting for patient related factors and surgery type.

CONCLUSIONS

Obesity class 2-3 status has prognostic value in predicting an increased incidence of postoperative complications, increased hospital LOS, and non-home discharge location. These results have important clinical implications for preoperative informed consent and provide areas to target for care improvement for the older obese individual.

Age, body mass index, and osteoporosis are more predictive than imaging for adjacent-segment reoperation after lumbar fusion

Background:

Adjacent-segment disease (ASD) is a well-described long-term complication after lumbar fusion. There is a lack of consensus about the risk factors for development of ASD, but identifying them could improve surgical outcomes. Our goal was to analyze the effect of patient characteristics and radiographic parameters on the development of symptomatic ASD requiring revision surgery after posterior lumbar fusion.

Methods:

In this retrospective cohort study, we identified patients who underwent lumbar fusion surgery and revision surgery from May 2012 to November 2018 using an institutional lumbar fusion registry. Patients having both pre- and post-operative upright radiographs were included in the study. Revision surgeries for which the index operation was performed at an outside hospital were excluded from analysis. Univariate analysis was conducted on candidate variables, and variables with P< 0.2 were selected for multivariate logistic regression.

Results:

Of the 106 patients identified, 21 required reoperation (29 months average follow-up). Age >65 years (OR 4.14, 95% CI 1.46–11.76, P= 0.008), body mass index (BMI) >34 (OR 1.13, 95% CI 1.04–1.23, P = 0.004), and osteoporosis (OR 14, 95% CI 1.38–142.42, P = 0.03) were independent predictors of reoperation in the multivariate analysis. Increased facet diastasis at fusion levels (OR 0.60, 95% CI 0.42–0.85, P = 0.004) was associated with reduced reoperation rates. Change in segmental LL at the index operation level, rostral and caudal facet diastasis, vacuum discs, and T2 hyperintensity in the facets were not predictors of reoperation.

Conclusion:

Age >65, BMI >34, and osteoporosis were independent predictors of adjacent-segment reoperation after lumbar spinal fusion.

Risk factors for venous thromboembolism following spinal surgery: A meta-analysis

BACKGROUND

To investigate the risk factors for postoperative venous thromboembolism (VTE) in patients undergoing spinal surgery.

METHODS

Literature published in PubMed, Embase, the Cochrane Library, and Web of Science was systematically reviewed to assess risk factors for VTE following spinal surgery. The data analysis was conducted with STATA 12.0. Data were pooled using fixed-effects or random-effects models according to the heterogeneity among the included studies.

RESULTS

Twenty-six studies involving 3,216,187 patients were included in this meta-analysis, and the total incidence of VTE after spinal surgery was 0.35% (0.15-29.38%). The pooled analysis suggested that the incidence of VTE after spinal surgery was higher in such aspects as increasing age (weighted mean difference [WMD] 0.55 years, 95% confidence interval [CI] 0.33-0.78, P < .001), female sex (odds ratio [OR] 1.12, 95% CI 1.01-1.25; P = .034), diabetes (OR 1.34, 95% CI 1.29-1.44; P < .001), chronic kidney disease (OR = 8.31, 95% CI 1.98-34.93; P = .004), nonambulatory preoperative activity status (OR 3.67, 95% CI 2.75-4.83; P < .001), D-dimer level (WMD 1.023, 95% CI 0.162-1.884; P = .02), long duration of operation (WMD 0.73, 95% CI 0.21-1.24; P = .006), spine fusion (OR 1.54, 95% CI 1.31-1.82; P < .001), and blood transfusion (OR 2.31, 95% CI 1.73-3.07; P < .001), and the differences were statistically significant. However, there were no significant differences in body mass index, obesity, hypertension, coronary heart disease, spondylolisthesis, intraoperative blood loss, surgical procedures (anterior lumbar interbody fusion vs posterior intervertebral fusion /translaminar lumbar interbody fusion), or surgical site (lumbar vs thoracic) (all P > .05).

CONCLUSION

Based on our meta-analysis, we identified several important factors that increased the risk of VTE after spinal surgery. We hope our study provides assistance to spine surgeons so that they can adequately analyze and assess risk factors in patients and then develop preventive measures to reduce the incidence of VTE.

Underweight patients are at just as much risk as super morbidly obese patients when undergoing anterior cervical spine surgery

BACKGROUND CONTEXT

Past studies have focused on the association of high body mass index (BMI) on spine surgery outcomes. These investigations have reported mixed conclusions, possible due to insufficient power, poor controlling of confounding variables, and inconsistent definitions of BMI categories (e.g. underweight, overweight, and obese). Few studies have considered outcomes of patients with low BMI.

PURPOSE

To analyze how anterior cervical spine surgery outcomes track with World Health Organization categories of BMI to better assess where along the BMI spectrum patients are at risk for adverse perioperative outcomes.

DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Patients undergoing elective anterior cervical spine surgery were abstracted from the 2005 to 2016 American College of Surgeons National Surgical Quality Improvement Program database.

OUTCOME MEASURES

Thirty-day adverse events, hospital readmissions, postoperative infections, and mortality.

METHODS

Patients undergoing anterior cervical spine procedures (anterior cervical discectomy and fusion, anterior cervical corpectomy, cervical arthroplasty) were identified in the 2005 to 2016 National Surgical Quality Improvement Program database. Patients were then aggregated into modified World Health Organization categories of BMI. Odds ratios of adverse outcomes, normalized to average risk of normal weight subjects (BMI 18.5-24.9 kg/m²), were calculated. Multivariate analyses were then performed on aggregated adverse outcome categories controlling for demographics (age, sex, functional status) and overall health as measured by the American Society of Anesthesiologists classification.

RESULTS

In total, 51,149 anterior cervical surgery patients met inclusion criteria. Multivariate analyses revealed the odds of any adverse event to be significantly elevated for underweight and super morbidly obese patients (Odds Ratios [OR] of 1.62 and 1.55, respectively). Additionally, underweight patients had elevated odds of serious adverse events (OR=1.74) and postoperative infections (OR=1.75) and super morbidly obese patients had elevated odds of minor adverse events (OR=1.72). Relative to normal BMI patients, there was no significant elevation for any adverse outcomes for any of the other overweight/obese categories, in fact some had reduced odds of various adverse outcomes.

CONCLUSIONS

Underweight and super morbidly obese patients have the greatest odds of adverse outcomes after anterior cervical spine surgery. The current study identifies underweight patients as an at-risk population that has previously not received significant focus. Physicians and healthcare systems should give additional consideration to this population, as they often already do for those at the other end of the BMI spectrum.

Prior bariatric surgery is associated with lower complications, in-hospital mortality, and healthcare utilization after elective spine fusion surgery

BACKGROUND

Grade 3 obesity could potentially increase postoperative complications after spinal fusion surgery. However, the relationship between prior bariatric surgery (BS) and postoperative complications after spinal fusion surgery is not well-established.

SETTING

Inpatient hospital admissions from the Nationwide Inpatient Sample.

METHODS

Patients with a primary procedure of spinal fusion surgery discharged between 2006 and 2014 were identified. In-hospital outcomes included postoperative complications, mortality, cost, and length of stay were compared between patients with prior BS and grade 3 obesity.

RESULTS

A total of 3,132,192 patients who underwent elective spinal fusion surgery were identified. There were 33,936 (1.1%) patients with a diagnosis of prior BS. The prevalence of prior BS increased significantly from .1% in 2006 to 1.5% in 2014. Compared with patients with grade 3 obesity, patients with prior BS were younger, more likely to be female, had less co-morbidities, and higher proportion of cervical surgery. Multivariable analysis indicated that patients with prior BS had lower risk of overall complications (odds ratio [OR]: .44; 95% confidence interval [CI]: .38-.49), neurologic (OR: .55; 95%CI: .35-.84), respiratory (OR: .30; 95%CI: .23-.37), cardiac (OR: .38; 95%CI: .24-.60), gastrointestinal (OR: .61; 95%CI: .44-.84), urinary and renal (OR: .34; 95%CI: .26-.44), venous thromboembolism (OR: .35; 95%CI: .19-.63), wound-related complications (OR: .67; 95%CI: .53-.85), and in-hospital mortality (OR: .12; 95%CI: .02-.88). Prior BS was also related to 13% shorter length of stay and 2% lower cost.

CONCLUSIONS

Among patients undergoing spinal fusion surgery, prior BS is associated with lower complications, in-hospital mortality, and healthcare utilization. BS might mitigate risk of worse outcomes associated with grade 3 obesity after spine fusion surgery.

Complexities of spine surgery in obese patient populations: a narrative review

The obese population is particularly challenging to the spine surgeon in all phases of care. A narrative literature review was performed to review difficulties in spine surgery on the obese patient population and techniques for mitigation. We specifically aimed to assess several topics with regard to this population: patient selection and preoperative care; intraoperative and surgical techniques; and postoperative care, outcomes, and complications. The literature review demonstrated that obese patients are at increased surgical risk with spine surgery due to a variety of factors at all stages of intervention. Preoperatively, obese patients have worse outcomes with physical therapy and present technical difficulties for injections. Transport to a hospital, imaging, resuscitation, and intubation are all challenged by increased body habitus. Intraoperatively, obese patients have increased operative times, blood loss, surgical site infections, and nerve palsies. Patient positioning and intraoperative imaging may be limited. Surgery itself may be technically challenging due to body habitus and minimally invasive techniques are becoming more prevalent in this population. Postoperatively, several studies demonstrate that obese patients have inferior outcomes compared with nonobese counterparts. Patient selection is a key for elective interventions, and appropriate infrastructure aids in the ultimate outcomes for both elective and nonelective surgical treatments. Overall, obese patients present several challenges to the spine surgeon, and certain precautions can be undertaken preoperatively, intraoperatively, and postoperatively to mitigate the associated risks to optimize outcomes.

Patients With Borderline Hip Dysplasia Achieve Clinically Significant Outcome After Arthroscopic Femoroacetabular Impingement Surgery: A Case-Control Study With Minimum 2-Year Follow-up

BACKGROUND

There is a growing trend for hip arthroscopists to treat patients with borderline hip dysplasia (BHD) for femoroacetabular impingement syndrome (FAIS) without addressing the acetabular coverage. However, the literature of outcomes and failure rates for these patients is conflicting.

PURPOSE

(1) To identify whether patients with BHD achieved 2-year similar patient-reported outcome, minimal clinically important difference (MCID), and patient acceptable symptomatic state (PASS) when compared with patients without BHD and (2) to identify predictors for achieving the MCID and PASS among patients with BHD who are undergoing hip arthroscopy for FAIS.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Data from consecutive patients who underwent primary hip arthroscopy with routine capsular closure for the treatment of FAIS between January 2012 and January 2017 were collected and retrospectively analyzed. Patients with BHD (lateral center-edge angle [LCEA], 20°-25°) were matched 2:1 by age, sex, and body mass index (BMI) to control patients with normal acetabular coverage (LCEA, >25°-40°). Patient-reported outcome, MCID, and PASS were compared between the groups. Multivariate logistic regression analysis identified significant predictors of achieving the MCID and PASS in the BHD group.

RESULTS

The MCID in the BHD group was defined as 9.2, 13.7, 8.5, and 15.2 for the Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sport Specific, modified Harris Hip Score, and iHOT-12, respectively. Threshold scores for achieving the PASS in both groups were 87.9, 76.4, 78.1, and 60.0. A total of 112 patients were identified as having BHD (LCEA, 20°-25°) and were matched to 224 controls. Both groups saw statistically significant increases in score averages over the 2-year period; however, the differences between them were not statistically significant (P > .05 for all). There was no statistical difference in the frequency of the BHD and non-BHD cohorts achieving the MCID on at least 1 threshold score (86.6% vs 85.6%, P = .837) and the PASS (78.6% vs 79.8%, P = .79). There was, however, a statistically significant difference between the rates of patients with and without BHD achieving the PASS on the modified Harris Hip Score threshold (62.5% vs 74.5%, P = .028). The final logistic models demonstrated that lower BMI (odds ratio [OR], 0.872; P = .029), lower preoperative alpha angle (OR, 0.965; P = .014), and female sex (OR, 3.647; P = .03) are independent preoperative predictors of achieving the MCID, while lower preoperative alpha angle (OR, 0.943; P = .018) and self-reported limp (OR, 18.53; P = .007) are independent preoperative predictors of achieving the PASS.

CONCLUSION

Outcome improvements in patients with BHD who are undergoing arthroscopic treatment with capsular closure for FAIS are not significantly different from patients with normal acetabular coverage. Lower BMI, lower alpha angle, absence of limp, and female sex are preoperative predictors of achieving meaningful clinically significant outcome improvements in patients with BHD.

Impact of obesity on outcomes following lumbar spine surgery: A systematic review and meta-analysis

The influence of obesity on spine surgery outcomes is highly controversial with a current clinical equipoise. Several studies suggest higher perioperative morbidity with obesity while other studies suggest otherwise. To address this gap in the literature, we conducted a systematic review and meta-analysis in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines with the objective of better defining the impact of obesity on outcomes following lumbar spine surgery. Risk of bias assessment was performed using the Newcastle-Ottawa Scale. Strength of evidence was assessed using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) Working Group system. Surgical outcomes such as blood loss, operative time, length of stay, complication and reoperation rates and functional outcomes represented by the change in Oswestry Disability Index and Visual Analog Scale-Back Pain were compared between obese and non-obese patients. A total of 32 studies with 23,415 patients were analyzed. Obese patients had slightly higher surgical blood loss (Mean Difference [MD]: 46.15 ml, CI: 20.21-72, p-value< .001, I² = 85%) and longer operative times (MD: 17.17 min, CI: 9.91-24.43, p-value< .001, I² = 95%), but similar length of stay as compared to non-obese patients. Higher complication (OR = 1.34, C.I. = 1.13-1.58, p = 0.01, I² = 45%) and reoperation rates (OR = 1.40, C.I. = 1.19-1.64, p < 0.001, I² = 20) were observed in obese patients. The differences, however, were not significant for obese patients undergoing MIS surgery. Functional outcomes (change in ODI and VAS-BP) were similar between the two groups. Overall confidence in GRADE estimates was either low or very low for all outcomes. Obesity might be linked to higher adverse events following lumbar spine surgery. Minimally invasive spine surgery, however, might offer comparable outcomes between obese and non-obese patients. However, further studies are needed to evaluate whether these findings remain valid for morbidly obese (BMI > 40) patients as well.

Use of the subcutaneous lumbar spine (SLS) index as a predictor for surgical complications in lumbar spine surgery

BACKGROUND CONTEXT

Lumbar spine surgeries require adequate exposure to visualize key structures and limited exposure can make surgery more technically difficult, thus increasing the potential for complications. Body mass index and body mass distribution have been shown to be associated with worse surgical outcomes.

PURPOSE

This study aims to further previous investigations in elucidating the predictive nature of body mass distribution with peri- and postoperative complications in lumbar surgery.

STUDY DESIGN/SETTING

This is a retrospective study conducted at a single institution.

PATIENT SAMPLE

Two hundred eighty-five patients who underwent lumbar laminectomy, laminotomy, or posterior lumbar interbody fusion or transforaminal lumbar interbody fusion procedures between 2013 and 2016.

OUTCOME MEASURES

Magnetic resonance imaging (MRI) results and electronic medical records were reviewed for measurements and relevant complications.

METHODS

Previously known risk factors were identified and MRI measurements of subcutaneous adipose depth (SAD) relative to spinous process height (SPH) were measured at the surgical site to generate the subcutaneous lumbar spine (SLS) index. This measurement was then analyzed in association with recorded surgical complications.

RESULTS

The SLS index was found to be a significant risk factor for total complications (0.292, p=.041), perioperative complications (0.202, p=.015), and need for revision surgery (0.285, p<.001). The SAD alone proved to be negatively associated with perioperative complications (-0.075, p=.034) and need for revision surgery (-0.104, p=.001), with no predictive association seen for total or postoperative complications. Linear regression revealed an SLS index of 3.43 as a threshold value associated with a higher risk of total complications, 5.8 for perioperative complications, and 3.81 for the need for revision surgeries.

CONCLUSION

Body mass distribution of the surgical site as indicated by SAD to SPH (SLS index) is significantly associated with increasing risk of postoperative and perioperative complications as well as increased likelihood for necessary revision surgery. This relationship was shown to be a more accurate indication of perioperative risk than previous standards of body mass index and SAD alone, and may allow spine surgeons to assess surgical risk when considering lumbar spine surgery using simple calculations from standard preoperative MRI results.

Prior bariatric surgery lowers complication rates following spine surgery in obese patients

BACKGROUND

Bariatric surgery (BS) is an increasingly common treatment for morbid obesity that has the potential to effect bone and mineral metabolism. The effect of prior BS on spine surgery outcomes has not been well established. The aim of this study was to assess differences in complication rates following spinal surgery for patients with and without a history of BS.

METHODS

Retrospective analysis of the prospectively collected New York State Inpatient Database (NYSID) years 2004-2013. BS patients and morbidly obese patients (non-BS) were divided into cervical and thoracolumbar surgical groups and propensity score matched for age, gender, and invasiveness and complications compared.

RESULTS

One thousand nine hundred thirty-nine spine surgery patients with a history of BS were compared to 1625 non-BS spine surgery patients. The average time from bariatric surgery to spine surgery is 2.95 years. After propensity score matching, 740 BS patients were compared to 740 non-BS patients undergoing thoracolumbar surgery, with similar comorbidity rates. The overall complication rate for BS thoracolumbar patients was lower than non-BS (45.8% vs 58.1%, P < 0.001), with lower rates of device-related (6.1% vs 23.2%, P < 0.001), DVT (1.2% vs 2.7%, P = 0.039), and hematomas (1.5% vs 4.5%, P < 0.001). Neurologic complications were similar between BS patients and non-BS patients (2.3% vs 2.7%, P = 0.62). For patients undergoing cervical spine surgery, BS patients experienced lower rates of bowel issues, device-related, and overall complication than non-BS patients (P < 0.05).

CONCLUSIONS

Bariatric surgery patients undergoing spine surgery experience lower overall complication rates than morbidly obese patients. This study warrants further investigation into these populations to mitigate risks associated with spine surgery for bariatric patients.