Robotic Versus Freehand Pedicle Screw Placement After One-to Three-Level Lumbar Fusion

AUTHORS

Brian A Karamian, Stephen L DiMaria, Andrew N Sawires, Jose A Canseco, Bryce A Basques, Gregory R Toci, Kris E Radcliff, Jeffrey A Rihn, I David Kaye, Alan S Hilibrand, Joseph K Lee, Christopher K Kepler, Alexander R Vaccaro, Gregory D Schroeder

JOURNAL

Global Spine J. 2021 Dec 7; 21925682211057491.

ABSTRACT

Study design: Retrospective cohort study.

Objectives: The purpose of this study is to compare patient-reported outcome measures (PROMs) for patients undergoing one-to three-level lumbar fusion using robotically assisted vs freehand pedicle screw placement.

Methods: Patients who underwent either robotically assisted or freehand pedicle screw placement for one-to three-level lumbar fusion surgery from January 1, 2014 to August 31, 2020 at a single academic institution were identified. Propensity score matching was performed based on demographic variables. Clinical and surgical outcomes were compared between groups. Recovery Ratios (RR) and the proportion of patients achieving the minimally clinically important difference (%MCID) were calculated for Oswestry Disability Index, PCS-12, MCS-12, VAS Back, and VAS Leg at 1 year. Surgical outcomes included complication and revision rates.

Results: A total of 262 patients were included in the study (85 robotic and 177 freehand). No significant differences were found in ΔPROM scores, RR, or MCID between patients who underwent robotically assisted vs freehand screw placement. The rates of revision (1.70% freehand vs 1.18% robotic, P = 1.000) and complications (.57% freehand vs 1.18% robotic, P = .546) were not found to be statically different between the 2 groups. Controlling for demographic factors, procedure type (robotic vs freehand) did not emerge as a significant predictor of ΔPROM scores on multivariate linear regression analysis.

Conclusions: Robotically assisted pedicle screw placement did not result in significantly improved clinical or surgical outcomes compared to conventional freehand screw placement for patients undergoing one-to three-level lumbar fusion.

Keywords: lumbar fusion; navigation; patient-reported outcomes; pedicle screw placement; robotically assisted surgery.

Risk Factors for Urinary Retention Following Posterior Lumbar Spinal Fusion

Authors

Jeremy D Mormol, Bryce A Basques, Garrett K Harada, Philip K Louie, Kevin Alter, Edward Goldberg, Matthew W Colman, Howard S An

Journal

Spine. 2021 Jan 15;46(2):E133-E138

Abstract

Study design: The study is designed as a retrospective cohort study.

Objective: The aim of this study was to identify modifiable and nonmodifiable risk factors of postoperative urinary retention in spine surgery patients.

Summary of background data: Postoperative urinary retention is a common complication in patients undergoing operative procedures requiring anesthesia. Current studies have shown significant risk factors for postoperative urinary retention, but most are nonmodifiable and subsequently of limited usefulness in preventing this complication. Several new studies have shown possible modifiable risk factors, but current data are inconsistent in terms of their statistical significance.

Methods: A total of 814 consecutive patients who underwent open posterior lumbar laminectomy and fusion were included in the retrospective cohort study. Pre, intra-, and postoperative characteristics were collected in all patients to identify risk factors for postoperative urinary retention.

Results: Glycopyrrolate use (odds ratio [OR] 2.60; P = 0.001), decreased body mass index (OR 0.96; P = 0.018), previous diagnosis of benign prostate hyperplasia (OR 3.34; P ≤ 0.001), and postoperative urinary tract infection (OR 5.60, P = 0.005) were associated with postoperative urinary retention. Previous history of lumbar spine surgery (OR 0.55; P = 0.019) was associated with decreased rates of postoperative urinary retention.

Conclusion: Glycopyrrolate use, benign prostate hyperplasia, and postoperative urinary tract infection were independent risk factors for postoperative urinary retention. The use of glycopyrrolate is a potentially modifiable risk factor for postoperative urinary retention.

Spine Patient Satisfaction With Telemedicine During the COVID-19 Pandemic: A Cross-Sectional Study

Authors

Alexander M Satin, Kartik Shenoy, Evan D Sheha, Bryce A Basques, Gregory D Schroeder, Alexander R Vaccaro, Isador H Lieberman, Richard D Guyer, Peter B Derman

Journal

Global Spine Journal. 2020 Oct 22. Online ahead of print.

Abstract

Study design: Original research, cross-sectional study.

Objectives: Evaluate patient satisfaction with spine care delivered via telemedicine. Identify patient- and visit-based factors associated with increased satisfaction and visit preference.

Methods: Telemedicine visits with a spine surgeon at 2 practices in the United States between March and May 2020 were eligible for inclusion in the study. Patients were sent an electronic survey recording overall satisfaction, technical or clinical issues encountered, and preference for a telemedicine versus an in-person visit. Factors associated with poor satisfaction and preference of telemedicine over an in-person visit were identified using multivariate logistic regression.

Results: A total of 772 responses were collected. Overall, 87.7% of patients were satisfied with their telemedicine visit and 45% indicated a preference for a telemedicine visit over an in-person visit if given the option. Patients with technical or clinical issues were significantly less likely to achieve 5 out of 5 satisfaction scores and were significantly more likely to prefer an in-person visit. Patients who live less than 5 miles from their surgeon's office and patients older than 60 years were also significantly more likely to prefer in-person visits.

Conclusions: Spine telemedicine visits during the COVID-19 pandemic were associated with high patient satisfaction. Additionally, 45% of respondents indicated a preference for telemedicine versus an in-patient visit in the future. In light of these findings, telemedicine for spine care may be a preferable option for a subset of patients into the future.

Keywords: COVID-19; patient satisfaction; spine surgery; telehealth; telemedicine.

Lumbar spinal fusion in the outpatient setting: an update on management, surgical approaches and planning

Authors

Bryce A Basques, Joseph Ferguson, Kyle N Kunze, Frank M Phillips

Journal

Journal of Spine Surgery. 2019 Sep;5(Suppl 2):S174-S180.

Abstract

Outpatient lumbar spinal fusion surgery has the potential for improved patient satisfaction, speed of recovery, and economic advantages when compared to inpatient surgery. Despite the rise in the number of these procedures performed annually, the literature on this topic remains scarce. As such, there is a need for a comprehensive review of current concepts in indications and management. The current review will present the most recent literature regarding pre-operative, intra-operative, and post-operative considerations when performing outpatient lumbar spinal fusion surgery.

Keywords: Outpatient; fusion; lateral; lumbar; posterior.

Review of robotic-assisted surgery: what the future looks like through a spine oncology lens

Authors

Arash J Sayari, Coralie Pardo, Bryce A Basques, Matthew W Colman

Journal

Annals of Translational Medicine. 2019 May;7(10):224.

Abstract

Recent advancements in medical technology have led to the emergence of robotic-assisted surgery with the hope of creating a safer and more efficient surgical environment for the patient and surgical team. Spine surgery and spine tumor surgery involve challenging anatomy and demand highly precise surgical maneuvers, creating an important niche for robotic systems. While still in its infancy, robotics in spine surgery have proven successful in pedicle screw placement. Similarly, robotics has begun to be used for accurate resections and surgical planning in tumor surgery. As future studies are published and robotics systems continue to evolve, we can expect more tactile haptic feedback and implementation of useful instruments to improve preoperative planning, resection guidance, and reconstruction during spine tumor surgery.

Keywords: Neoplasm metastasis; neoplasms; robotics; spinal cord neoplasms; spine; surgery, computer assisted.

The Effect of Preoperative Symptom Duration on Postoperative Outcomes After a Tubular Lumbar Microdiscectomy

Authors

Bryce A Basques, Brittany E Haws, Benjamin Khechen, Philip K Louie, Dil V Patel, Mundeep S Bawa, Kamran Movassaghi, Kaitlyn L Cardinal, Jordan A Guntin, Kern Singh

Journal

Clinical Spine Surgery. 2019 Feb;32(1):E27-E30.

Abstract

Study design: This is a retrospective cohort study.

Objective: This study aims to characterize the effect of preoperative symptom duration on postoperative outcomes after minimally invasive lumbar microdiscectomy (MIS LD).

Summary of background data: It is unknown whether extended nonoperative treatment before MIS LD has implications for long-term clinical outcomes even after surgery is performed.

Materials and methods: A prospectively maintained surgical registry of patients undergoing MIS LD by a single surgeon between 2013 and 2017 was reviewed. Preoperative symptom duration was dichotomized into 2 groups (≤6 and >6 mo). Only patients with full clinical data at 6 months postoperative follow-up were included in the study. Clinical outcomes were assessed at 6, 12 weeks, and 6 months after surgery. The number of patients obtaining a minimum clinically important difference was assessed. Groups were compared with the χ analysis and the student t tests for categorical and continuous data, respectively.

Results: In total, 94 patients were identified. A total of 45 patients (47.9%) had symptom duration ≤6 months. No differences in baseline characteristics were found (P>0.05). Patients with shorter symptom duration had significantly greater improvement in Oswestry Disability Index scores at 6 weeks (P=0.004), 12 weeks (P=0.022), and 6 months (P=0.005). Patients with shorter duration of symptoms also obtained minimum clinically important difference for Oswestry Disability Index at a greater rate than those with longer duration of symptoms (P=0.015).

Conclusions: Although patients who underwent MIS LD within 6 months of symptom onset had similar baseline characteristics compared with patients who underwent surgery after 6 months of symptoms, the patients with longer preoperative symptom duration had worse functional outcomes at 6 months after surgery. These results suggest that earlier MIS lumbar microdiscectomy may provide a functional benefit for patients. Further studies should therefore evaluate the efficacy of nonoperative treatment in the setting of lumbar herniated nucleus pulposus, as prolonged conservative management may potentially impair functional recovery after surgery.

Multi- versus single-level anterior cervical discectomy and fusion: comparing sagittal alignment, early adjacent segment degeneration, and clinical outcomes

Authors

Bryce A Basques, Philip K Louie, Jeremy Mormol, Jannat M Khan, Kamran Movassaghi, Justin C Paul, Arya Varthi, Edward J Goldberg, Howard S An

Journal

European Spine Journal

Abstract

Purpose: The purpose of this study was to compare the rates of adjacent segment degeneration (ASD), sagittal alignment parameters, and patient-reported outcomes in patients who underwent multi-level versus single-level anterior cervical discectomy and fusion (ACDF).

Methods: A retrospective cohort analysis was performed on consecutive patients who underwent an ACDF. Pre- and post-operative radiographic assessment included ASD, change in C2-C7 lordosis, T1 angle, levels fused, sagittal vertical axis (SVA), fusion mass lordosis, proximal and distal adjacent segment lordosis. Patient-reported outcomes were obtained.

Results: Of the 404 that underwent an ACDF with a minimum of 6 months of follow-up (average 28 months), there was no significant difference in the rate of radiographic ASD overall (p = 0.479) or in the proximal or distal adjacent segments on multivariate analysis. Secondarily, the multi-level fusions appear to restore significantly greater amounts of lordosis compared to single-level procedures (p < 0.001) and are able to maintain the corrected cervical lordosis and fusion segment lordosis over time. From the immediate post-operative period to final follow-up, the single-level ACDFs show continuing lordosis improvement (p = 0.005) that is significantly greater than that of the multi-level constructs. There were no significant differences between pre-operative, post-operative, or change in patient-reported outcomes.

Conclusions: Two years following an ACDF, patients who underwent multi-level fusions appear to restore significantly greater amounts of lordosis compared to single-level procedures, while single-level ACDFs show significantly greater amounts of lordosis improvement over time. Multi-level procedures may not be at a significantly greater risk of developing early radiographic evidence of ASD compared to single-level procedure. These slides can be retrieved under Electronic Supplementary Material.

Keywords: Adjacent segment degeneration; Anterior cervical discectomy fusion; Multi-level surgery; Radiculopathy; Single-level surgery.

Sex Differences for Anterior Cervical Fusion: Complications and Length of Stay

Authors

Bryce A Basques, Fady Y Hijji, Benjamin Khechen, Brittany E Haws, Benjamin C Mayo, Dustin H Massel, Philip K Louie, Kaitlyn L Cardinal, Jordan A Guntin, Kern Singh

Journal

Spine. 2018 Aug 1;43(15):1025-1030.

Abstract

Study design: Retrospective cohort.

Objective: To assess differences in baseline characteristics between sexes of patients undergoing anterior cervical discectomy and fusion (ACDF) and risk factors for adverse outcomes according to sex.

Summary of background data: ACDF is a common treatment for cervical spine disease. To reduce the rate of complications, risk factors associated with adverse events have been identified. However, few studies have examined the risk for inferior outcomes or complications after ACDF by sex.

Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients who underwent ACDF from 2005 through 2014. Data collected included demographics, comorbidities, operative characteristics, and postoperative adverse events. Demographic and comorbidity variables were compared between men and women using chi-squared analysis. Perioperative outcomes were compared between groups using multivariate linear regression or Poisson regression with robust error variance controlling for preoperative characteristics.

Results: In the 20,383 patients who met inclusion criteria, the male cohort was slightly older, less likely to be normal weight or morbidly obese, and had a higher incidence of diabetes and hypertension (P < 0.001 for each). Male sex was associated with a greater risk of any adverse event (relative risk = 1.2; P = 0.043), as well as any severe adverse event (relative risk = 1.4; P = 0.001). Moreover, male sex exhibited longer operative times compared to the female group (127 vs. 117 min; β = 10; P < 0.001).

Conclusion: The results of the current study suggest male sex is associated with an increased risk of adverse events following ACDF. Male sex has previously been demonstrated to correlate with medical comorbidities, which may be partly responsible for the increased morbidity. Because of the contrasting evidence throughout the literature, further studies are required to better elucidate this effect.

Results of Database Studies in Spine Surgery Can Be Influenced by Missing Data

Authors

Bryce A Basques, Ryan P McLynn, Michael P Fice, Andre M Samuel, Adam M Lukasiewicz, Daniel D Bohl, Junyoung Ahn, Kern Singh, Jonathan N Grauer

Journal

Clinical Orthopaedics and Related Research. 2017 Dec;475(12):2893-2904

Abstract

Background: National databases are increasingly being used for research in spine surgery; however, one limitation of such databases that has received sparse mention is the frequency of missing data. Studies using these databases often do not emphasize the percentage of missing data for each variable used and do not specify how patients with missing data are incorporated into analyses. This study uses the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database to examine whether different treatments of missing data can influence the results of spine studies.

Questions/purposes: (1) What is the frequency of missing data fields for demographics, medical comorbidities, preoperative laboratory values, operating room times, and length of stay recorded in ACS-NSQIP? (2) Using three common approaches to handling missing data, how frequently do those approaches agree in terms of finding particular variables to be associated with adverse events? (3) Do different approaches to handling missing data influence the outcomes and effect sizes of an analysis testing for an association with these variables with occurrence of adverse events?

Methods: Patients who underwent spine surgery between 2005 and 2013 were identified from the ACS-NSQIP database. A total of 88,471 patients undergoing spine surgery were identified. The most common procedures were anterior cervical discectomy and fusion, lumbar decompression, and lumbar fusion. Demographics, comorbidities, and perioperative laboratory values were tabulated for each patient, and the percent of missing data was noted for each variable. These variables were tested for an association with "any adverse event" using three separate multivariate regressions that used the most common treatments for missing data. In the first regression, patients with any missing data were excluded. In the second regression, missing data were treated as a negative or "reference" value; for continuous variables, the mean of each variable's reference range was computed and imputed. In the third regression, any variables with > 10% rate of missing data were removed from the regression; among variables with ≤ 10% missing data, individual cases with missing values were excluded. The results of these regressions were compared to determine how the different treatments of missing data could affect the results of spine studies using the ACS-NSQIP database.

Results: Of the 88,471 patients, as many as 4441 (5%) had missing elements among demographic data, 69,184 (72%) among comorbidities, 70,892 (80%) among preoperative laboratory values, and 56,551 (64%) among operating room times. Considering the three different treatments of missing data, we found different risk factors for adverse events. Of 44 risk factors found to be associated with adverse events in any analysis, only 15 (34%) of these risk factors were common among the three regressions. The second treatment of missing data (assuming "normal" value) found the most risk factors (40) to be associated with any adverse event, whereas the first treatment (deleting patients with missing data) found the fewest associations at 20. Among the risk factors associated with any adverse event, the 10 with the greatest effect size (odds ratio) by each regression were ranked. Of the 15 variables in the top 10 for any regression, six of these were common among all three lists.

Conclusions: Differing treatments of missing data can influence the results of spine studies using the ACS-NSQIP. The current study highlights the importance of considering how such missing data are handled.

Clinical relevance: Until there are better guidelines on the best approaches to handle missing data, investigators should report how missing data were handled to increase the quality and transparency of orthopaedic database research. Readers of large database studies should note whether handling of missing data was addressed and consider potential bias with high rates or unspecified or weak methods for handling missing data.

Kinematics of the Lumbar Spine Vary Depending on the Levels of Motion

Authors

Bryce A Basques, Alejandro A Espinoza Orías, Grant D Shifflett, Michael P Fice, Gunnar B Andersson, Howard S An, Nozomu Inoue

Journal

Spine. 2017 Jul 1;42(13):E767-E774.

Abstract

Study design: A prospective cohort study.

Objective: The aim of this study was to identify associations of spondylotic and kinematic changes with low back pain (LBP).

Summary of background data: The ability to characterize and differentiate the biomechanics of both the symptomatic and asymptomatic lumbar spine is crucial to alleviate the sparse literature on the association of lumbar spine biomechanics and LBP.

Methods: Lumbar dynamic plain radiographs (flexion-extension), dynamic computed tomography (CT) scanning (axial rotation, disc height), and magnetic resonance imaging (MRI, disc and facet degeneration grades) were obtained for each subject. These parameters were compared between symptomatic and control groups using Student t test and multivariate logistic regression, which controlled for patient age and sex and identified spinal parameters that were independently associated with symptomatic LBP. Disc grade and mean segmental motion by level were tested by one-way analysis of variance (ANOVA).

Results: Ninety-nine volunteers (64 asymptomatic/35 LBP) were prospectively recruited. Mean age was 37.3 ± 10.1 years and 55% were male. LBP showed association with increased L5/S1 translation [odds ratio (OR) 1.63 per mm, P = 0.005], decreased flexion-extension motion at L1/L2 (OR 0.87 per degree, P = 0.036), L2/L3 (OR 0.88 per degree, P = 0.036), and L4/L5 (OR 0.87 per degree, P = 0.020), increased axial rotation at L4/L5 (OR 2.11 per degree, P = 0.032), decreased disc height at L3/L4 (OR 0.52 per mm, P = 0.008) and L4/L5 (OR 0.37 per mm, p < 0.001), increased disc grade at all levels (ORs 2.01-12.33 per grade, P = 0.001-0.026), and increased facet grade at L4/L5 (OR 4.99 per grade, P = 0.001) and L5/S1 (OR 3.52 per grade, P = 0.004). Significant associations were found between disc grade and kinematic parameters (flexion-extension motion, axial rotation, and translation) at L4/L5 (P = 0.001) and L5/S1 (P < 0.001), but not at other levels (P > 0.05).

Conclusion: In symptomatic individuals, L4/L5 and L5/S1 levels were affected by spondylosis and kinematic changes. This study clarifies the relationships between kinematic alterations and LBP, mostly observed at the above-mentioned segments.

Predicting Postoperative Morbidity and Readmission for Revision Posterior Lumbar Fusion

Authors

Bryce A Basques, Izuchukwu Ibe, Andre M Samuel, Adam M Lukasiewicz, Matthew L Webb, Daniel D Bohl, Jonathan N Grauer

Journal

Clinical Spine Surgery. 2017 Jul; Volume 30, Issue 6. Pages E770-E775.

Abstract

Study design: Retrospective cohort study.

Objective: The primary aim of this study was to determine the incidence and risk factors for 30-day adverse events after revision posterior lumbar fusion. The secondary aim was to determine the incidence and risk factors for 30-day readmission after revision posterior lumbar fusion.

Summary of background data: The need for revision of a lumbar fusion is an unfortunate occurrence, and there is little known about specific risk factors for morbidity and readmission after this procedure. The purpose of this study is to use a large, national sample to identify patient and operative factors that may contribute to the development of these adverse outcomes.

Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients undergoing revision posterior lumbar fusion from 2005 to 2013. Patient characteristics were tested for association with any adverse event (AAE), severe adverse events (SAEs), minor adverse events (MAEs), and readmission within 30 days postoperatively using multivariate analysis.

Results: Of the 1287 patients identified, 8.2% had an AAE, 5.6% had an SAE, and 3.2% had an MAE. AAE was independently associated with American Society of Anesthesiologists (ASA) classification ≥3 and operative time ≥310 minutes (P<0.05 for each). SAEs were associated with only ASA classification ≥3 (P=0.047). MAEs were associated with insulin-dependent diabetes, operative time ≥310 minutes, and 3 or more levels of fusion (P<0.05 for all).Sixty-five patients (5.6%) were readmitted. On multivariate analysis, body mass index (BMI) 25-30, BMI 30-35, BMI≥35, ASA classification ≥3, insulin-dependent diabetes, a 2-level fusion, and 3 or more levels of fusion were associated with readmission (P<0.05 for all).

Conclusions: In general, longer, more extensive procedures on sicker patients were associated with increased risk of postoperative complications and readmission.

Poor visualization limits diagnosis of proximal junctional kyphosis in adolescent idiopathic scoliosis

Authors

Bryce A Basques, William D Long 3rd, Nicholas S Golinvaux, Daniel D Bohl, Andre M Samuel, Adam M Lukasiewicz, Matthew L Webb, Jonathan N Grauer

Journal

The Spine Journal. 2017 Jun;17(6):784-789.

Abstract

Background context: Multiple methods are used to measure proximal junctional angle (PJA) and diagnose proximal junctional kyphosis (PJK) after fusion for adolescent idiopathic scoliosis (AIS); however, there is no gold standard. Previous studies using the three most common measurement methods, upper-instrumented vertebra (UIV)+1, UIV+2, and UIV to T2, have minimized the difficulty in obtaining these measurements, and often exclude patients for which measurements cannot be recorded.

Purpose: The purpose of this study is to assess the technical feasibility of measuring PJA and PJK in a series of AIS patients who have undergone posterior instrumented fusion and to assess the variability in results depending on the measurement technique used.

Study design/setting: A retrospective cohort study was carried out.

Patient sample: There were 460 radiographs from 98 patients with AIS who underwent posterior spinal fusion at a single institution from 2006 through 2012.

Outcome measures: The outcomes for this study were the ability to obtain a PJA measurement for each method, the ability to diagnose PJK, and the inter- and intra-rater reliability of these measurements.

Methods: Proximal junctional angle was determined by measuring the sagittal Cobb angle on preoperative and postoperative lateral upright films using the three most common methods (UIV+1, UIV+2, and UIV to T2). The ability to obtain a PJA measurement, the ability to assess PJK, and the total number of patients with a PJK diagnosis were tabulated for each method based on established definitions. Intra- and inter-rater reliability of each measurement method was assessed using intra-class correlation coefficients (ICCs).

Results: A total of 460 radiographs from 98 patients were evaluated. The average number of radiographs per patient was 5.3±1.7 (mean±standard deviation), with an average follow-up of 2.1 years (780±562 days). A PJA measurement was only readable on 13%-18% of preoperative filmsand 31%-49% of postoperative films (range based on measurement technique). Only 12%-31% of films were able to be assessed for PJK based on established definitions. The rate of PJK diagnosis ranged from 1% to 29%. Of these diagnoses, 21%-100% disappeared on at least one subsequent film for the given patient. ICC ranges for intra-rater and inter-rater reliability were 0.730-0.799 and 0.794-0.836, respectively.

Conclusions: This study suggests significant limitations of the three most common methods of measuring and diagnosing PJK. The results of studies using these methods can be significantly affected based on the exclusion of patients for whom measurements cannot be made and choice of measurement technique.

Keywords: Adolescent idiopathic scoliosis; Measurement; Posterior spinal fusion; Proximal junctional angle; Proximal junctional kyphosis; Radiograph.

Effect of Surgeon Volume on Complications, Length of Stay, and Costs Following Anterior Cervical Fusion

Authors

Bryce A Basques, Philip K Louie, Grant D Shifflett, Michael P Fice, Benjamin C Mayo, Dustin H Massel, Javier Z Guzman, Daniel D Bohl, Kern Singh

Journal

Spine. 2017 Mar 15; Volume 42, Issue 6, Pages 394-399

Abstract

Study design: Retrospective cohort.

Objective: To identify the association between surgeon volume and inpatient complications, length of stay, and costs associated with ACF.

Summary of background data: Increased surgeon volume may be associated with improved outcomes after surgical procedures. However, there is a lack of information on the effect of surgeon volume on short-term outcomes after anterior cervical fusion (ACF).

Methods: A retrospective cohort study of ACF patients was performed using the Nationwide Inpatient Sample (NIS) from 2003 to 2009. Surgeon volume was divided into three categories, volume <25th percentile, 25th to 74th percentile, and ≥75th percentile of surgeon volume. Multivariate regression was used to compare the rates of adverse events, hospital length of stay, and total hospital costs between surgeon volume categories.

Results: A total of 419,212 ACF patients were identified. The 25th percentile for volume was 5 cases per year, and the 75th percentile for volume was 67 cases per year. Volume <25th percentile was associated with increased rates of any adverse event (odd ratio, OR 3.8, P < 0.001), and multiple individual complications including death (OR 2.5, P=0.014), myocardial infarction (OR4.4, P < 0.001), sepsis (OR 4.1, P < 0.001), and surgical site infection (OR 4.0, P < 0.001). Notably, volume ≥75th percentile was associated with decreased rates of any adverse event (OR 0.7, P < 0.001) and death (OR 0.6, P = 0.028). On multivariate analysis, length of stay was significantly increased by 2.3 days (P < 0.001) for surgeons <25th percentile of volume and was decreased by 0.3 days for surgeons with volume ≥75th percentile. Hospital costs were $4569 more for surgeons with <25th percentile of volume and $1213 less for surgeons with ≥75th percentile volume.

Conclusion: In this nationally representative sample, surgeons with volume <25th percentile had significantly increased complications, length of stay, and costs. Conversely, surgeons with ≥75th percentile volume experienced decreased complications, length of stay, and costs.

Risk Factors for Blood Transfusion With Primary Posterior Lumbar Fusion

Authors

Bryce A Basques, Nidharshan S Anandasivam, Matthew L Webb, Andre M Samuel, Adam M Lukasiewicz, Daniel D Bohl, Jonathan N Grauer

Journal

Spine. 2015 Nov; Volume 40, Issue 22, Pages 1792-7.

Abstract

Study design: Retrospective cohort study.

Objective: To identify factors associated with blood transfusion for primary posterior lumbar fusion surgery, and to identify associations between blood transfusion and other postoperative complications.

Summary of background data: Blood transfusion is a relatively common occurrence for patients undergoing primary posterior lumbar fusion. There is limited information available describing which patients are at increased risk for blood transfusion, and the relationship between blood transfusion and short-term postoperative outcomes is poorly characterized.

Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients undergoing primary posterior lumbar fusion from 2011 to 2013. Multivariate analysis was used to find associations between patient characteristics and blood transfusion, along with associations between blood transfusion and postoperative outcomes.

Results: Out of 4223 patients, 704 (16.7%) had a blood transfusion. Age 60 to 69 (relative risk [RR] 1.6), age greater than equal to 70 (RR 1.7), American Society of Anesthesiologists class greater than equal to 3 (RR 1.1), female sex (RR 1.1), pulmonary disease (RR 1.2), preoperative hematocrit less than 36.0 (RR 2.0), operative time greater than equal to 310 minutes (RR 2.9), 2 levels (RR 1.6), and 3 or more levels (RR 2.1) were independently associated with blood transfusion. Interbody fusion (RR 0.9) was associated with decreased rates of blood transfusion. Receiving a blood transfusion was significantly associated with any complication (RR 1.7), sepsis (RR 2.6), return to the operating room (RR 1.7), deep surgical site infection (RR 2.6), and pulmonary embolism (RR 5.1). Blood transfusion was also associated with an increase in postoperative length of stay of 1.4 days (P < 0.001).

Conclusion: 1 in 6 patients received a blood transfusion while undergoing primary posterior lumbar fusion, and risk factors for these occurrences were characterized. Strategies to minimize blood loss might be considered in these patients to avoid the associated complications.

Analysis of Delays to Surgery for Cervical Spinal Cord Injuries

Authors

Andre M Samuel, Daniel D Bohl, Bryce A Basques, Pablo J Diaz-Collado, Adam M Lukasiewicz, Matthew L Webb, Jonathan N Grauer

Journal

Spine. 2015 Jul 1; Volume 40, Issue 13, Pages 992-1000.

Abstract

Study design: A retrospective study of surgically treated patients with cervical spinal cord injury (SCI) from the National Trauma Data Bank Research Data Set.

Objective: To determine how time to surgery differs between SCI subtypes, where delays before surgery occur, and what factors are associated with delays.

Summary of background data: Studies have shown that patients with cervical SCI undergoing surgery within 24 hours after injury have superior neurological outcomes to patients undergoing later surgery, with most evidence coming from the incomplete SCI subpopulation.

Methods: Surgically treated patients with cervical SCI from 2011 and 2012 were identified in National Trauma Data Bank Research Data Set and divided into subpopulations of complete, central, and other incomplete SCIs. Relationships between surgical timing and patient and injury characteristics were analyzed using multivariate regression.

Results: A total of 2636 patients with cervical SCI were identified: 803 with complete SCI, 950 with incomplete SCI, and 883 with central SCI. The average time to surgery was 51.1 hours for patients with complete SCI, 55.3 hours for patients with incomplete SCI, and 83.1 hours for patients with central SCI. Only 44% of patients with SCI underwent surgery within the first 24 hours after injury, including only 49% of patients with incomplete SCI.The vast majority of time between injury and surgery was after admission, rather than in the emergency department or in the field. Upper cervical SCIs and greater Charlson Comorbidity Index were associated with later surgery in all 3 SCI subpopulations.

Conclusion: The majority of patients with SCI do not undergo surgery within the first 24 hours after injury, and the majority of delays occur after inpatient admission. Factors associated with these delays highlight areas of focus for expediting care in these patient populations.

Limitations of administrative databases in spine research

Authors

Nicholas S Golinvaux, Daniel D Bohl, Bryce A Basques, Michael C Fu, Elizabeth C Gardner, Jonathan N Grauer

Journal

The Spine Journal. 2014-12-01; Volume 14, Issue 12, Pages 2923-8.

Abstract

Background context: The use of national inpatient databases for spine surgery research has been increasing. Unfortunately, without firsthand knowledge of each specific database, it can be difficult to judge the validity of such studies. Large databases that rely on administrative data, such as International Classification of Diseases, Ninth Revision (ICD-9) codes, may misrepresent patient information and could thus affect the results of studies that use these data.

Purpose: The present study uses obesity, an easily quantified and objective variable, as an example comorbidity to assess the accuracy of ICD-9 codes in the setting of their continued use in spine database studies.

Study design/setting: A cross-sectional study at a large academic medical center.

Patient sample: All patients spending at least one night in the hospital as an inpatient between April 1, 2013 and April 16, 2013. Obstetrics and gynecology, psychiatry, and pediatric patients were excluded.

Outcome measures: Proportion of patients for whom ICD-9 obesity diagnosis codes assigned at hospital discharge match chart-documented body mass index (BMI).

Methods: The medical record was reviewed for each patient, and obesity ICD-9 codes were directly compared with documented BMI.

Results: The study included 2,075 patients. Of 573 "obese" patients (calculated BMI 30-39.9), only 109 received the correct code (278.00), giving this ICD-9 code a sensitivity of 0.19. Of 174 "morbidly obese" patients (calculated BMI >40), only 84 received the correct code (278.01), giving this ICD-9 code a sensitivity of 0.48.

Conclusions: Using obesity as an example, this study highlights the potential errors inherent to using ICD-9-coded databases for spine surgery research. Should a study based on such data use "obesity" as a variable in any analyses, the reader should interpret these results with caution. We further suggest that obesity is likely not the only comorbidity to which these results apply. As database research continues to represent an increasing proportion of publications in the field of spine surgery, it is important to realize that study outcomes can be skewed by data accuracy, and, thus, should not be blindly accepted simply by virtue of large sample sizes.

Keywords: Body mass index; Database; ICD-9; Morbid obesity; Obesity; Spine.

Use of an operating microscope during spine surgery is associated with no increased risk of infection

Authors

Bryce A Basques, Nicholas S Golinvaux, Daniel D Bohl, Alem Yacob, Jason O Toy, Arya G Varthi, Jonathan N Grauer

Journal

Spine. 2014-10-15; Volume 39, Issue 22, Pages 1910-6.

Abstract

Study design: Retrospective database review.

Objective: To evaluate whether microscope use during spine procedures is associated with increased operating room times or increased risk of infection.

Summary of background data: Operating microscopes are commonly used in spine procedures. It is debated whether the use of an operating microscope increases operating room time or confers increased risk of infection.

Methods: The American College of Surgeons National Surgical Quality Improvement Program database, which includes data from more than 370 participating hospitals, was used to identify patients undergoing elective spinal procedures with and without the use of an operating microscope for the years 2011 and 2012. Bivariate and multivariate linear regressions were used to test the association between microscope use and operating room times. Bivariate and multivariate logistic regressions were similarly conducted to test the association between microscope use and infection occurrence within 30 days of surgery.

Results: A total of 23,670 elective spine procedures were identified, of which 2226 (9.4%) used an operating microscope. The average patient age was 55.1±14.4 years. The average operative time (incision to closure) was 125.7±82.0 minutes.Microscope use was associated with minor increases in preoperative room time (+2.9 min, P=0.013), operative time (+13.2 min, P<0.001), and total room time (+18.6 min, P<0.001) on multivariate analysis.A total of 328 (1.4%) patients had an infection within 30 days of surgery. Multivariate analysis revealed no significant difference between the microscope and nonmicroscope groups for occurrence of any infection, superficial surgical site infection, deep surgical site infection, organ space infection, or sepsis/septic shock, regardless of surgery type.

Conclusion: We did not find operating room times or infection risk to be significant deterrents for use of an operating microscope during spine surgery.

The "July effect" in elective spine surgery

Authors

Daniel D Bohl, Michael C Fu, Jordan A Gruskay, Bryce A Basques, Nicholas S Golinvaux, Jonathan N Grauer

Journal

Spine, 2014-04-01; Volume 39, Issue 7, Pages 603-11.

Abstract

Study design: Retrospective cohort.

Objective: To evaluate for the presence and magnitude of the "July effect" within elective spine surgery.

Summary of background data: The July effect is the hypothetical increase in morbidity and mortality thought to be associated with the influx of new (or newly promoted) trainees during the first portion of the academic year. Studies evaluating for the presence and magnitude of the July effect have demonstrated conflicting results.

Methods: We accessed the American College of Surgeons National Surgical Quality Improvement Program database from 2005-2010. Statistical analyses were conducted using bivariate and multivariate logistic regression.

Results: A total of 14,986 cases met inclusion criteria and constitute the study population. Of these, 26.5% occurred in the first academic quarter and 25.3% had resident involvement. The rate of serious adverse events was 1.9 times higher and the rate of any adverse events was 1.6 times higher among cases with resident involvement than among those without (P < 0.001 for both). Among cases without resident involvement, the rates of serious adverse events and any adverse events did not differ by academic quarter. Similarly, among cases with resident involvement, the rates of serious adverse events and any adverse events did not differ by academic quarter.

Conclusion: We could not demonstrate that the training of new (or newly promoted) residents is associated with an increase in the adverse events of spine surgery. Safeguards that have been put in place to ensure patient safety during this training period seem to be effective. Although adverse events were more common among cases with resident involvement than among cases without resident involvement, our data suggest that this association is more likely a product of the riskier population of cases in which residents participate than of the resident involvement itself.