Top 25 Most-Cited Articles on Robotic-Assisted Lumbar Spine Surgery

BACKGROUND

Robot-guided lumbar spine surgery has evolved rapidly with evidence to support its utility and feasibility compared with conventional freehand and fluoroscopy-based techniques. The objective of this study was to assess trends among the top 25 most-cited articles pertaining to robotic-guided lumbar spine surgery.

METHODS

An "advanced document search" using Boolean search operator terms was performed on 16 November 2022 through the Web of Science and SCOPUS citation databases to determine the top 25 most-referenced articles on robotic lumbar spine surgery. The articles were compiled into a directory and hierarchically organized based on the total number of citations.

RESULTS

Cumulatively, the "Top 25" list for robot-assisted navigation in lumbar spine surgery received 2240 citations, averaging 97.39 citations annually. The number of citations ranged from 221 to 40 for the 25 most-cited articles. The most-cited study, by Kantelhardt et al, received 221 citations, averaging 18 citations per year.

CONCLUSIONS

As utilization of robot-guided modalities in lumbar spine surgery increases, this review highlights the most impactful studies to support its efficacy and implementation. Practical considerations such as cost-effectiveness, however, need to be better defined through further longitudinal studies that evaluate patient-reported outcomes and cost-utility.

CLINICAL RELEVANCE

Through an overview of the top 25 most-cited articles, the present review highlights the rising prominence and technical efficacy of robotic-guided systems within lumbar spine surgery, with consideration to pragmatic limitations and need for additional data to facilitate cost-effective applications.

LEVEL OF EVIDENCE: 5

AO Spine Guideline for the Use of Osteobiologics (AOGO) in Anterior Cervical Discectomy and Fusion for Spinal Degenerative Cases

STUDY DESIGN

Guideline.

OBJECTIVES

To develop an international guideline (AOGO) about the use of osteobiologics in anterior cervical discectomy and fusion (ACDF) for treating degenerative spine conditions.

METHODS

The guideline development process was guided by AO Spine Knowledge Forum Degenerative (KF Degen) and followed the Guideline International Network McMaster Guideline Development Checklist. The process involved 73 participants with expertise in degenerative spine diseases and surgery from 22 countries. Fifteen systematic reviews were conducted addressing respective key topics and evidence was collected. The methodologist compiled the evidence into GRADE Evidence-to-Decision frameworks. Guideline panel members judged the outcomes and other criteria and made the final recommendations through consensus.

RESULTS

Five conditional recommendations were created. A conditional recommendation is about the use of allograft, autograft or a cage with an osteobiologic in primary ACDF surgery. Other conditional recommendations are about the use of osteobiologic for single- or multi-level ACDF, and for hybrid construct surgery. It is suggested that surgeons use other osteobiologics rather than human bone morphogenetic protein-2 (BMP-2) in common clinical situations. Surgeons are recommended to choose 1 graft over another or 1 osteobiologic over another primarily based on clinical situation, and the costs and availability of the materials.

CONCLUSION

This AOGO guideline is the first to provide recommendations for the use of osteobiologics in ACDF. Despite the comprehensive searches for evidence, there were few studies completed with small sample sizes and primarily as case series with inherent risks of bias. Therefore, high-quality clinical evidence is demanded to improve the guideline.

Comparison of Different Osteobiologics in Terms of Imaging Modalities and Time Frames for Fusion Assessment in Anterior Cervical Discectomy and Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

The study's primary objective was to determine how osteobiologic choice affects fusion rates in patients undergoing anterior cervical discectomy and fusion (ACDF). The study's secondary objectives were to 1) determine the optimal timing of fusion assessment following ACDF and 2) determine if osteobiologic type affects the timing and optimal modality of fusion assessment.

METHODS

A systematic search of PubMed/MEDLINE was conducted for literature published from 2000 through October 2020 comparing anterior fusion in the cervical spine with various osteobiologics. Both comparative studies and case series of ≥10 patients were included.

RESULTS

A total of 74 studies met the inclusion criteria. Seventeen studies evaluated the efficacy of autograft on fusion outcomes, and 23 studies assessed the efficacy of allograft on fusion outcomes. 3 studies evaluated the efficacy of demineralized bone matrix, and seven assessed the efficacy of rhBMP-2 on fusion outcomes. Other limited studies evaluated the efficacy of ceramics and bioactive glasses on fusion outcomes, and 4 assessed the efficacy of stem cell products. Most studies utilized dynamic radiographs for the assessment of fusion. Overall, there was a general lack of supportive data to determine the optimal timing of fusion assessment meaningfully or if osteobiologic type influenced fusion timing.

CONCLUSIONS

Achieving fusion following ACDF appears to remain an intricate interplay between host biology and various surgical factors, including the selection of osteobiologics. While alternative osteobiologics to autograft exist and may produce acceptable fusion rates, limitations in study methodology prevent any definitive conclusions from existing literature.

What Is the Evidence Supporting Osteobiologic Use in Revision Anterior Cervical Discectomy and Fusion?

STUDY DESIGN

Systematic literature review.

OBJECTIVE

To analyze the literature and describe the evidence supporting osteobiologic use in revision anterior cervical discectomy and fusion (ACDF) surgery.

METHODS

A systematic search of PubMed/MEDLINE, EMBASE, Cochrane library, and ClinicalTrials.gov databases was conducted for literature reporting the use of osteobiologics in revision ACDF. We searched for studies reporting outcomes of using any osteobiologic use in revision ACDF surgeries (independently of the number of levels) in the above databases.

RESULTS

There are currently no studies in the literature describing the outcome and comparative efficacy of diverse osteobiologic agents in the context of revision ACDF surgery. A majority of the current evidence is based only upon studies involving primary ACDF surgery.

CONCLUSION

The current study highlights the paucity of literature evidence on the role of diverse osteobiologics in revision ACDF, and foregrounds the need for high-quality evidence on this subject.

Surgeon Preferences Worldwide in Wound Drain Utilization in Open Lumbar Fusion Surgery for Degenerative Pathologies

STUDY DESIGN

Cross-sectional survey.

OBJECTIVE

Although literature does not recommend routine wound drain utilization, there is a disconnect between the evidence and clinical practice. This study aims to explore into this controversy and analyze the surgeon preferences related to drain utilization, and the factors influencing drain use and criterion for removal.

METHODS

A survey was distributed to AO Spine members worldwide. Surgeon demographics and factors related to peri-operative drain use in 1 or 2-level open fusion surgery for lumbar degenerative pathologies were collected. Multivariate analyses by drain utilization, and criterion of removal were conducted.

RESULTS

231 surgeons participated, including 220 males (95.2%), orthopedics (178, 77.1%), and academic/university-affiliated (114, 49.4%). Most surgeons preferred drain use (186, 80.5%) and subfascial drains (169, 73.2%). Drains were removed based on duration by 52.87% of the surgeons, but 27.7% removed drains based on outputs. On multivariable analysis, significant predictors of drain use were surgeon's aged 35-44 (OR = 11.9, 95% CI = 1.2-117.2, P = .034), 45-54 (29.1, 3.1-269.6, P = .003), 55-64 (8.9, 1.4-56.5, .019), and wound closure using coaptive films (6.0, 1.2-29.0, P = .025). Additionally, surgeons from Asia Pacific (OR = 5.19, 95% CI = 1.65-16.38, P = .005), Europe (3.55, 1.22-10.31, P = .020), and Latin America (4.40, 1.09-17.83, .038) were more likely to remove drain based on time duration, but surgeons <5 years of experience (10.23, 1.75-59.71, P = .010) were more likely to remove drains based on outputs.

CONCLUSIONS

Most spine surgeons worldwide prefer to place a subfascial wound drain for degenerative open lumbar surgery. The choice for drain placement is associated with the surgeon's age and use of coaptive films for wound closure, while the criterion for drain removal is associated with the surgeons' region of practice and experience.

SPINE20 recommendations 2023: One Earth, one family, one future WITHOUT spine DISABILITY

Introduction

The purpose is to report on the fourth set of recommendations developed by SPINE20 to advocate for evidence-based spine care globally under the theme of "One Earth, One Family, One Future WITHOUT Spine DISABILITY".

Research question

Not applicable.

Material and methods

Recommendations were developed and refined through two modified Delphi processes with international, multi-professional panels.

Results

Seven recommendations were delivered to the G20 countries calling them to:-establish, prioritize and implement accessible National Spine Care Programs to improve spine care and health outcomes.-eliminate structural barriers to accessing timely rehabilitation for spinal disorders to reduce poverty.-implement cost-effective, evidence-based practice for digital transformation in spine care, to deliver self-management and prevention, evaluate practice and measure outcomes.-monitor and reduce safety lapses in primary care including missed diagnoses of serious spine pathologies and risk factors for spinal disability and chronicity.-develop, implement and evaluate standardization processes for spine care delivery systems tailored to individual and population health needs.-ensure accessible and affordable quality care to persons with spine disorders, injuries and related disabilities throughout the lifespan.-promote and facilitate healthy lifestyle choices (including physical activity, nutrition, smoking cessation) to improve spine wellness and health.

Discussion and conclusion

SPINE20 proposes that focusing on the recommendations would facilitate equitable access to health systems, affordable spine care delivered by a competent healthcare workforce, and education of persons with spine disorders, which will contribute to reducing spine disability, associated poverty, and increase productivity of the G20 nations.

Using machine learning and big data for the prediction of venous thromboembolic events after spine surgery: A single-center retrospective analysis of multiple models on a cohort of 6869 patients

Objective

Venous thromboembolic event (VTE) after spine surgery is a rare but potentially devastating complication. With the advent of machine learning, an opportunity exists for more accurate prediction of such events to aid in prevention and treatment.

Methods

Seven models were screened using 108 database variables and 62 preoperative variables. These models included deep neural network (DNN), DNN with synthetic minority oversampling technique (SMOTE), logistic regression, ridge regression, lasso regression, simple linear regression, and gradient boosting classifier. Relevant metrics were compared between each model. The top four models were selected based on area under the receiver operator curve; these models included DNN with SMOTE, linear regression, lasso regression, and ridge regression. Separate random sampling of each model was performed 1000 additional independent times using a randomly generated training/testing distribution. Variable weights and magnitudes were analyzed after sampling.

Results

Using all patient-related variables, DNN using SMOTE was the top-performing model in predicting postoperative VTE after spinal surgery (area under the curve [AUC] =0.904), followed by lasso regression (AUC = 0.894), ridge regression (AUC = 0.873), and linear regression (AUC = 0.864). When analyzing a subset of only preoperative variables, the top-performing models were lasso regression (AUC = 0.865) and DNN with SMOTE (AUC = 0.864), both of which outperform any currently published models. Main model contributions relied heavily on variables associated with history of thromboembolic events, length of surgical/anesthetic time, and use of postoperative chemoprophylaxis.

Conclusions

The current study provides promise toward machine learning methods geared toward predicting postoperative complications after spine surgery. Further study is needed in order to best quantify and model real-world risk for such events.

SPINE20 recommendations 2022: spine care-working together to recover stronger

PURPOSE

Globally, spine disorders are the leading cause of disability, affecting more than half a billion individuals. However, less than 50% of G20 countries specifically identify spine health within their public policy priorities. Therefore, it is crucial to raise awareness among policy makers of the disabling effect of spine disorders and their impact on the economic welfare of G20 nations. In 2019, SPINE20 was established as the leading advocacy group to bring global attention to spine disorders.

METHODS

Recommendations were developed through two Delphi methods with international and multi-professional panels.

RESULTS

In 2022, seven recommendations were delivered to the leaders of G20 countries, urging them to: Develop action plans to provide universal access to evidence-based spine care that incorporates the needs of minorities and vulnerable populations. Invest in the development of sustainable human resource capacity, through multisectoral and inter-professional competency-based education and training to promote evidence-based approaches to spine care, and to build an appropriate healthcare working environment that optimizes the delivery of safe health services. Develop policies using the best available evidence to properly manage spine disorders and to prolong functional healthy life expectancy in the era of an aging population. Create a competent workforce and improve the healthcare infrastructure/facilities including equipment to provide evidence-based inter-professional rehabilitation services to patients with spinal cord injury throughout their continuum of care. Build collaborative and innovative translational research capacity within national, regional, and global healthcare systems for state-of-the-art and cost-effective spine care across the healthcare continuum ensuring equality, diversity, and inclusion of all stakeholders. Develop international consensus statements on patient outcomes and how they can be used to define and develop pathways for value-based care. Recognize that intervening on determinants of health including physical activity, nutrition, physical and psychosocial workplace environment, and smoking-free lifestyle can reduce the burden of spine disabilities and improve the health status and wellness of the population. At the third SPINE20 summit 2022 which took place in Bali, Indonesia, in August 2022, 17 associations endorsed its recommendations.

CONCLUSION

SPINE20 advocacy efforts focus on developing public policy recommendations to improve the health, welfare, and wellness of all who suffer from spinal pain and disability. We propose that focusing on facilitating access to systems that prioritize value-based care delivered by a competent healthcare workforce will reduce disability and improve the productivity of the G20 nations.

Abstract GS102: Injection Of Human IPSC-derived Cardiac Cells Promote Cardiac Repair After Infarction In Nonhuman Primates

Introduction: Injection of induced pluripotent stem cell-derived cardiomyocytes has been reported as a promising approach to regenerate loss myocardium and restore heart function after ischemic injury. However, immaturity of the transplanted cardiomyocytes and their poor survival rates caused by limited blood supply remain as major hurdles for clinical translation.

Hypothesis: We tested the hypothesis that co-culture of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) with hiPSC-derived endothelial cells (ECs) promotes CM maturation in vitro, and that co-transplantation of both hiPSC-CMs and hiPSC-ECs facilitates hiPSC-CM muscularization in myocardial ischemic injured mice and non-human primates.

Methods and Results: We examined the therapeutic effect of co-transplantation of hiPSC-CMs and hiPSC-ECs in NOD-SCID mice undergoing myocardial infarction (N = 14 / group). Mice receiving co-transplantation had an improvement in ejection fraction compared to control (4.2 ± 1.2 % vs -8.4 ± 0.9 %, P < 0.0001), and even those receiving high-dose (-0.3 ± 0.9 %, P = 0.052) and low-dose (-2.4 ± 1.1 %, P = 0.001) hiPSC-CMs alone treatment. Moreover, less arrhythmic events were observed in co-transplantation using three-lead electrogram. To be more clinically relevant, we first showed in healthy non-human primates (N = 4) that hiPSC-CM engraftment, maturation, and integration was achieved when co-transplanted with hiPSC-ECs. Furthermore, we then examined the therapeutic effect of co-transplantation of hiPSC-CMs and hiPSC-ECs in rhesus macaques undergoing ischemia-reperfusion surgery (N = 3 / group). Consistent with the mouse model, co-transplantation in rhesus macaques significantly improved the ejection fraction (10 ± 1.3 % vs -1.8 ± 2.2 %, P = 0.010), accompanied by a reduced infarct size compared to control (16 ± 1.1 % vs 23 ± 3.3 %, P = 0.091).

Conclusions: This study demonstrates the beneficial effects of co-transplantation of hiPSC-CMs with hiPSC-ECs, promoting hiPSC-CM maturation, enhancing neovascularization, and improving cardiac function in both mouse and non-human primate hearts. Delivery of this combined cell therapy holds promise for future clinical translation.

Abstract P2016: Gut Microbiota-derived Short-chain Fatty Acids Benefit Cardiac Extracellular Matrix Remodeling In Pressure Overload

Introduction: The gut microbiota has been implicated in various heart diseases by producing metabolites that modulate host immunity and metabolism. In our previous study, we found that mice with dysbiosis suffered more from cardiac rupture, resulting in higher mortality than mice possessing commensal gut flora after myocardial infarction. This suggests that there are unexplored routes to cardiovascular health through the gut microbiota.

Hypothesis: We hypothesize that a community of symbiotic gut microbiota is required for heart mechanical modifications during adaptive cardiac remodeling under stress.

Methods and Results: Pressure-overload stress was induced by a transverse aortic constriction (TAC) surgery and dysbiosis was induced by antibiotic treatment (ABX) in mice. Under echocardiography, ABX-TAC mice showed worse cardiac outcomes versus controls (ejection fraction = 59% ± 2% vs 67% ± 2%, P < 0.001, N ≥ 12/group). Under microscopic examination of the extracellular matrix and tensile tests, ABX-TAC mice had larger fibrotic areas (9.4% ± 0.4% vs 5.7% ± 0.4%, P < 0.0001) and collagen disarray, accompanied by more severe ventricular stiffening (Young’s moduli = 360 ± 10 kPa vs 280 ± 43 kPa, P < 0.01, N ≥ 6/group). When establishing normal gut flora before surgery, germ-free mice had heart malfunctioning rescued (change of myocardial performance index = 15% ± 13% vs 120% ± 32% untreated, P < 0.05, N ≥ 5/group). The normal gut flora was profiled by third-generation 16S sequencing to acquire bacterial information with high accuracy, followed by PICRUSt analysis revealing that the microbes favored the production of short-chain fatty acids (SCFAs) (N ≥ 8/group). When supplemented with SCFA before surgery, ABX mice gained better cardiac outcomes (ejection fraction = 65% ± 2% vs 53% ± 3% untreated, P < 0.01, N ≥ 5/group). Cardiac fibroblasts treated with SCFA were less susceptible to TGF-β1-triggered fibrogenesis (COL1A1/GAPDH = 0.8 ± 0.3 vs 2.3 ± 0.3 untreated, P < 0.01, n ≥ 4/group).

Conclusions: In conclusion, our study demonstrates firstly that gut microbiota-derived SCFAs manipulate heart mechanical functioning under stress potentially acting via cardiac fibroblasts. This provides new insights into the management of heart diseases through the gut microbiota.

Abstract P3120: Cardio And Neurotoxicity Of Repurposed Anti-COVID-19 Drugs

In December 2019, the novel coronavirus disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) spread around the globe resulting in ~435 million confirmed cases and ~6 million related deaths as of March 2022, according to the World Health Organization. To combat COVID-19 quickly, there have been many attempts to repurpose current FDA-approved drugs or to revive old drugs with anti-viral properties. However, aside from the biological stress imposed by the virus, many of the current treatment options have been known to cause adverse drug reactions. We established a population-based human induced pluripotent stem cell drug screening platform to assess the toxicity of the first line of anti-COVID-19 drugs and to understand viral infection of cardiomyocytes and neurons. We found that iPSC-derived cardiomyocytes express the ACE2 receptor which correlated with a higher infection of the SARS-CoV-2 virus (r=0.86). However, ACE2 expression was undetectable in neurons which correlated with low infection of neurons. We then assessed the toxicity of anti-COVID-19 drugs and identified two cardiotoxic compounds (remdesivir and arbidol) and 4 neurotoxic compounds (arbidol, remdesivir, hydroxychloroquine, and chloroquine) which were validated by dose-response curves. These data show that this platform can quickly and easily be employed to further our understanding of cell-specific infection and identify drug toxicity of potential treatment options helping clinicians better decide on treatment options.

Abstract P1009: Size And Distribution Of Human Cardiac Tissue Grafts Following Transendocardial Delivery Of Committed Cardiac Progenitors In A Swine Ischemic Heart Failure Model

Introduction: iPSC-derived committed cardiac progenitor cells (CCP) have exciting potential to remuscularize infarcted myocardium; however, little is known about CCP engraftment and differentiation following injection. We hypothesized that transendocardial injection (TEI) of CCPs with an injectable cardiac fibroblast derived extracellular matrix (ECM) retention agent would result in cardiac tissue grafts in an immunosuppressed porcine ischemic heart failure (HF) model.

Methods: Coronary artery balloon-occlusion myocardial infarction was induced in Yucatan mini-swine. After 1 month, 300M CCPs with and without 50 mg ECM particles were delivered in 15 intramyocardial injections to the border zone and infarct zone using a steerable Myostar injection catheter with NOGA XP mapping. Immunosuppressed swine were sacrificed up to 2 months following treatment. Hearts were systematically sectioned and stained for human nuclear antigen (Ku80) and cardiac troponin I/T to define the area and distribution of human grafts and cardiomyocyte content.

Results: Clusters of human grafts composed of predominantly troponin positive cardiomyocytes were observed in the infarct, at the infarct border, and in adjacent healthy tissue. Overall, 21/25 (84%) of treated pigs had human cardiac tissue grafts. In the current analysis, grafts were identified in 11/12 (91.6%) and 10/13 (76.9%) of pigs in the CCP+ECM and CCP, respectively (see Figure). The observed mean graft area was 62,930 ± 40,332 μm 2 and 185,200 ± 329,080 μm 2 per pig in the CCP+ECM and CCP only groups, respectively (p=0.23).

Conclusion: In an immunosuppressed swine ischemic HF model, TEI of CCPs ± ECM yields persistent human cardiac tissue grafts composed of predominantly of cardiomyocytes in both infarcted and non-infarcted regions of the myocardium up to 2 months following treatment.

The performance of frailty in predictive modeling of short-term outcomes in the surgical management of metastatic tumors to the spine

BACKGROUND CONTEXT

The concept of frailty has become increasingly recognized, and while patients with cancer are at increased risk for frailty, its influence on perioperative outcomes in metastatic spine tumors is uncertain. Furthermore, the impact of frailty can be confounded by comorbidities or metastatic disease burden.

PURPOSE

The purpose of this study was to evaluate the influence of frailty and comorbidities on adverse outcomes in the surgical management of metastatic spine disease.

STUDY DESIGN/SETTING

Retrospective analysis of a nationwide database to include patients undergoing spinal fusion for metastatic spine disease.

PATIENT SAMPLE

A total of 1,974 frail patients who received spinal fusion with spinal metastasis, and 1,975 propensity score matched non-frail patients.

OUTCOME MEASURES

Outcomes analyzed included mortality, complications, length of stay (LOS), nonroutine discharges and costs.

METHODS

A validated binary frailty index (Johns Hopkins Adjusted Clinical Groups) was used to identify frail and non-frail groups, and propensity score-matched analysis (including demographics, comorbidities, surgical and tumor characteristics) was performed. Sub-group analysis of levels involved was performed for cervical, thoracic, lumbar and junctional spine. Multivariable-regression techniques were used to develop predictive models for outcomes using frailty and the Elixhauser Comorbidity Index (ECI).

RESULTS

7,772 patients underwent spinal fusion with spinal metastasis, of which 1,974 (25.4%) patients were identified as frail. Following propensity score matching for frail (n=1,974) and not-frail (n=1,975) groups, frailty demonstrated significantly greater medical complications (OR=1.58; 95% CI 1.33-1.86), surgical complications (OR=1.46; 95% CI 1.15-1.85), LOS (OR=2.65; 95% CI 2.09-3.37), nonroutine discharges (OR=1.79; 95% CI 1.46-2.20) and costs (OR=1.68; 95% CI 1.32-2.14). Differences in mortality were only observed in subgroup analysis and were greater in frail junctional and lumbar spine subgroups. Models using ECI alone (AUC=0.636-0.788) demonstrated greater predictive ability compared to those using frailty alone (AUC=0.633-0.752). However, frailty combined with ECI improved the prediction of increased LOS (AUC=0.811), cost (AUC=0.768), medical complications (AUC=0.723) and nonroutine discharges (AUC=0.718). Predictive modeling of frailty in subgroups demonstrated the greatest performance for mortality (AUC=0.750) in the lumbar spine, otherwise performed similarly for LOS, costs, complications, and discharge across subgroups.

CONCLUSIONS

A high prevalence of frailty existed in the current patient cohort. Frailty contributed to worse short-term adverse outcomes and could be more influential in the lumbar and junctional spine due to higher risk of deconditioning in the postoperative period. Predictions for short term outcomes can be improved by adding frailty to comorbidity indices, suggesting a more comprehensive preoperative risk stratification should include frailty.

Autologous Stem Cells in Cervical Spine Fusion

STUDY DESIGN

Systematic review.

OBJECTIVES

To systematically review, critically appraise and synthesize evidence on use of stem cells from autologous stem cells from bone marrow aspirate, adipose, or any other autologous sources for fusion in the cervical spine compared with other graft materials.

METHODS

A systematic search of PubMed/MEDLINE was conducted for literature published through October 31, 2018 and through February 20, 2020 for EMBASE and ClinicalTrials.gov comparing autologous cell sources for cervical spine fusion to other graft options.

RESULTS

From 36 potentially relevant citations identified, 10 studies on cervical fusion met the inclusion criteria set a priori. Two retrospective cohort studies, one comparing cancellous bone marrow (CBM) versus hydroxyapatite (HA) and the other bone marrow aspirate (BMA) combined with autograft and HA versus autograft and HA alone, were identified. No statistical differences were seen between groups in either study for improvement in function, symptoms, or fusion; however, in the study evaluating BMA, the authors reported a statistically greater fusion rate and probability of fusion over time in the BMA versus the non-BMA group. Across case series evaluating BMA, authors reported improved function and pain and fusion ranged from 84% to 100% across the studies. In general, complications were poorly reported.

CONCLUSIONS

The overall quality (strength) of evidence of effectiveness and safety of autologous BMA for cervical arthrodesis in the current available literature was very low. Based on currently available data, firm conclusions regarding the effectiveness or safety of BMA in cervical fusions cannot be made.

The influence of modifiable risk factors on short-term postoperative outcomes following cervical spine surgery: A retrospective propensity score matched analysis

BACKGROUND

Modifiable risk factors (MRFs) represent patient variables associated with increased complication rates that may be prevented. There exists a paucity of studies that comprehensively analyze MRF subgroups and their independent association with postoperative complications in patients undergoing cervical spine surgery. Therefore, the purpose of this study is to compare outcomes between patients receiving cervical spine surgery with reported MRFs.

METHODS

Retrospective analysis of the Nationwide Readmissions Database (NRD) from the years 2016 and 2017, a publicly available and purchasable data source, to include adult patients undergoing cervical fusion. MRF cohorts were separated into three categories: substance abuse (alcohol, tobacco/nicotine, opioid abuse); vascular disease (hypertension, dyslipidemia); and dietary factors (malnutrition, obesity). Three-way nearest-neighbor propensity score matching for demographics, hospital, and surgical characteristics was implemented.

FINDINGS

We identified 9601 with dietary MRFs (D-MRF), 9654 with substance abuse MRFs (SA-MRF), and 9503 with vascular MRFs (V-MRF). Those with d-MRFs had significantly higher rates of medical complications (9.3%), surgical complications (8.1%), and higher adjusted hospital costs compared to patients with SA-MRFs and V-MRFs. Patients with d-MRFs (16.3%) and V-MRFs (14.0%) were independently non-routinely discharged at a significantly higher rate compared to patients with SA-MRFs (12.6%) (p<0.0001 and p = 0.0037). However, those with substance abuse had the highest readmission rate and were more commonly readmitted for delayed procedure-related infections.

INTERPRETATION

A large proportion of patients who receive cervical spine surgery have potential MRFs that uniquely influence their postoperative outcomes. A thorough understanding of patient-specific MRF subgroups allows for improved preoperative risk stratification, tailored patient counseling, and postoperative management planning.

FUNDING

None.

Impact of a Perioperative Protocol on Length of ICU and Hospital Stay in Complex Spine Surgery

BACKGROUND

In an attempt to improve patient care, a perioperative complex spine surgery management protocol was developed through collaboration between spine surgeons and neuroanesthesiologists. The aim of this study was to investigate whether implementation of the protocol in 2015 decreased total hospital and intensive care unit (ICU) length of stay (LOS) and complication rates after elective complex spine surgery.

MATERIALS AND METHODS

A retrospective cohort study was conducted by review of the medical charts of patients who underwent elective complex spine surgery at an academic medical center between 2012 and 2017. Patients were divided into 2 groups based on the date of their spine surgery in relation to implementation of the spine surgery protocol; before-protocol (January 2012 to March 2015) and protocol (April 2015 to March 2017) groups. Outcomes in the 2 groups were compared, focusing on hospital and ICU LOS, and complication rates.

RESULTS

A total of 201 patients were included in the study; 107 and 94 in the before-protocol and protocol groups, respectively. Mean (SD) hospital LOS was 14.8±10.8 days in the before-protocol group compared with 10±10.7 days in the protocol group (P<0.001). The spine surgery protocol was the primary factor decreasing hospital LOS; incidence rate ratio 0.78 (P<0.001). Similarly, mean ICU LOS was lower in the protocol compared with before-protocol group (4.2±6.3 vs. 6.3±7.3 d, respectively; P=0.011). There were no significant differences in the rate of postoperative complications between the 2 groups (P=0.231).

CONCLUSION

Implementation of a spine protocol reduced ICU and total hospital LOS stay in high-risk spine surgery patients.

Comparison of Minimally Invasive Versus Open Transforaminal Interbody Lumbar Fusion

STUDY DESIGN

Narrative review.

OBJECTIVES

In this review, we address the question of whether the literature supports the notion that minimally invasive transforaminal interbody fusion (MIS-TLIF) improves outcome as compared with open TLIF (open-TLIF). Short and long-term outcomes, fusion rate, and cost-effectiveness were reviewed.

METHODS

This is a narrative review using various databases. Open-TLIF and MIS-TLIF studies were included and posterior lumbar interbody fusion studies were excluded. A description of paramedian incision in surgical technique was essential to the definition of MIS-TLIF. The present review included 14 prospective observational studies and 6 randomized controlled trials.

RESULTS

With short-term outcomes, some studies indicate a better outcome with MIS-TLIF regarding intraoperative bleeding, hospital stay, time to ambulation, postoperative narcotic use, and time to resume work. Both MIS-TLIF and open-TLIF surgeries improved Oswestry Disability Index, back pain, and leg pain. Some studies show that MIS-TLIF resulted in lower back pain than open-TLIF. Radiation exposure was higher with MIS-TLIF. In the longer term, clinical outcomes were improved in both MIS and open TLIF groups. Fusion rates were more than 90% in both MIS-TLIF and open-TLIF. Cost-effectiveness and length of surgery had mixed results.

CONCLUSIONS

The potential benefits of MIS-TLIF might be present in the early recovery period after surgery. Long-term outcomes were similar with both MIS-TLIF and open-TLIF.

Allogenic Stem Cells in Spinal Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

To review, critically appraise, and synthesize evidence on the use of allogenic stem cell products for spine fusion compared with other bone graft materials.

METHODS

Systematic searches of PubMed/MEDLINE, through October 31, 2018 and of EMBASE and ClinicalTrials.gov through April 13, 2018 were conducted for literature comparing allogenic stem cell sources for fusion in the lumbar or cervical spine with other fusion methods. In the absence of comparative studies, case series of ≥10 patients were considered.

RESULTS

From 382 potentially relevant citations identified, 6 publications on lumbar fusion and 5 on cervical fusion met the inclusion criteria. For lumbar arthrodesis, mean Oswestry Disability Index (ODI), visual analogue scale (VAS) pain score, and fusion rates were similar for anterior lumbar interbody fusion (ALIF) using allogenic multipotent adult progenitor cells (Map3) versus recombinant human bone morphogenetic protein-2 (rhBMP-2) in the one comparative lumbar study (90% vs 92%). Across case series of allogenic stem cell products, function and pain were improved relative to baseline and fusion occurred in ≥90% of patients at ≥12 months. For cervical arthrodesis across case series, stem cell products improved function and pain compared with baseline at various time frames. In a retrospective cohort study fusion rates were not statistically different for Osteocel compared with Vertigraft allograft (88% vs 95%). Fusion rates varied across time frames and intervention products in case series.

CONCLUSIONS

The overall quality (strength) of evidence of effectiveness and safety of allogenic stem cells products for lumbar and cervical arthrodesis was very low, meaning that we have very little confidence that the effects seen are reflective of the true effects.

Cell Therapy for Treatment of Intervertebral Disc Degeneration: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To review, critically appraise, and synthesize evidence on use of cell therapy for intervertebral disc repair.

METHODS

A systematic search of PubMed/MEDLINE was conducted for literature published through October 31, 2018 and EMBASE and ClinicalTrials.gov databases through April 13, 2018 comparing allogenic or autologous cell therapy for intervertebral disc (IVD) repair in the lumbar or cervical spine. In the absence of comparative studies, case series of ≥10 patients were considered.

RESULTS

From 1039 potentially relevant citations, 8 studies across 10 publications on IVD cell therapies in the lumbar spine met the inclusion criteria. All studies were small and primarily case series. For allogenic cell sources, no difference in function or pain between mesenchymal cell treatment and sham were reported in 1 small randomized controlled trial; 1 small case series reported improved function and pain relative to baseline but it was unclear if the change was clinically significant. Similarly for autologous cell sources, limited data across case series suggest pain and function may be improved relative to baseline; whether the changes were clinically significant was not clear. Safety data was sparse and poorly reported. The need for subsequent surgery was reported in 3 case-series studies ranging from 6% to 80%.

CONCLUSIONS

The overall strength of evidence for efficacy and safety of cell therapy for lumbar IVD repair was very low primarily due to substantial risk of bias, small sample sizes and lack of a comparator intervention. Methodologically sound studies comparing cell therapies to other treatments are needed.

Simulation of Dural Repair in Minimally Invasive Spine Surgery With the Use of a Perfusion-Based Cadaveric Model

BACKGROUND AND IMPORTANCE

In an era of curtailed work hours and concerns over achieving technical proficiency in the repertoire of procedures necessary for independent practice, many residencies have turned to model simulation as an educational adjunct. Cerebrospinal fluid (CSF) leak repair after inadvertent durotomy in spine surgery is a fundamental skillset for any spine surgeon. While primary closure with suture is not always necessary for small durotomies, larger defects, on the other hand, must be repaired. However, the dire consequences of inadequate repair dictate that it is generally performed by the most experienced surgeon. Few intraoperative opportunities, therefore, exist for CSF leak repair by trainees.

OBJECTIVE

To simulate dural repair in spine surgery using minimal-access techniques.

METHODS

A cohort of 8 neurosurgery residents was evaluated on their durotomy repair efforts in a perfusion-based cadaveric model.

RESULTS

Study participants demonstrated consistent improvement across trials, with a significant reduction in closure times between their initial (12 min, 7 sec ± 4 min, 43 sec) and final attempts (7 min, 4 sec ± 2 min, 6 sec; P = .02). Moreover, all trainees—irrespective of postgraduate year—were able to accomplish robust dural closures resistant to simulated Valsalva maneuvers. Participants reported high degrees of model realism and exhibited significant increases in postprocedure confidence scores.

CONCLUSION

Our results support use of perfusion-based simulation models as a complement to neurosurgery training, as it affords unrestricted opportunities for honing psychomotor skillsets when resident learning is increasingly being challenged by work-hour limitations and stricter oversight in the context of value-based healthcare.

Risk Factors Associated with Reconstructive Complications Following Sacrectomy

BACKGROUND

Sacral pathology requiring partial or total sacrectomy is rare, and reconstructing the ensuing defects requires careful decision-making to minimize morbidity. The purpose of this study was to review the experience of a single institution with reconstructing large sacral defects, to identify risk factors for suboptimal outcomes.

METHODS

A retrospective chart review was conducted of all patients who underwent sacrectomy over a 10-year period. Univariate analysis of differences in risk factors between patients with and without various postoperative complications was performed. Multivariate logistic regression was used to identify predictive variables.

RESULTS

Twenty-eight patients were identified. The most common diagnosis leading to sacrectomy was chordoma (39%). Total sacrectomy was performed on 4 patients, whereas 24 patients underwent partial resection. Reconstructive modalities included 15 gluteal advancement flaps, 4 pedicled rectus abdominis myocutaneous flaps, and 9 paraspinous muscle or other flap types. There was an overall complication rate of 57.1% (n = 12) and a 28.6% (n = 8) incidence of major complications. There were significantly more flap-related complications in patients who underwent total sacrectomy (P = 0.02). Large defect size resulted in significantly more unplanned returns to the operating room (P < 0.01).

CONCLUSION

Consistent with other published series', the overall complication rate exceeded 50%. Defect volume and sacrectomy type were the strongest predictors of postoperative complications and return to the operating room, while reconstructive strategy showed limited power to predict patient outcomes. We recommend that patients anticipated to have large sacral defects should be appropriately counseled regarding the incidence of wound complications, regardless of reconstructive approach.

Paraplegic patients: how to measure balance and what is normal or functional?

PURPOSE

To review the current understanding and data of sagittal balance and alignment considerations in paraplegic patients.

METHODS

A PubMed literature search was conducted to identify all relevant articles relating to sagittal alignment and sagittal balance considerations in paraplegic and spinal cord injury patients.

RESULTS

While there are numerous studies and publications on sagittal balance in the ambulatory patient with spinal deformity or complex spine disorders, there is paucity of the literature on "normal" sagittal balance in the paraplegic patients. Studies have reported significantly alterations of the sagittal alignment parameters in the non-ambulatory paraplegic patients compared to ambulatory patients. The variability of the alignment changes is related to the differences in the level of the spinal cord injury and their differences in the activations of truncal muscles to allow functional movements in those patients, particularly in optimizing sitting and transferring. Surgical goal in treating paraplegic patients with complex pathologies should not be solely directed to achieve the "normal" radiographic parameters of sagittal alignment in the ambulatory patients. The goal should be to maintain good coronal balance to allow ideal sitting position and to preserve motion segment to optimize functions of paraplegia patients.

CONCLUSION

Current available literature data have not defined normal sagittal parameters for paraplegic patients. There are significant differences in postural sagittal parameters and muscle activations in paraplegic and non-spinal cord injury patients that can lead to differences in sagittal alignment and balance. Treatment goal in spine surgery for paraplegic patients should address their global function, sitting balance, and ability to perform self-care rather than the accepted radiographic parameters for adult spinal deformity in ambulatory patients.

The primary diagnosis and the coexisting anxiety disorders have no impact on the additional surgical procedure after spinal cord stimulators implantation: An analysis of 11,029 patients

Studies have demonstrated superior outcomes and cost effectiveness of the spinal cord stimulation (SCS) for the treatment of chronic pain syndromes such as failed back surgery syndrome (FBSS) or complex regional pain syndrome (CRPS). However, little is known about the impact of primary diagnosis or mental disorders on the revision rate. This is the Retrospective cohort study to analyze the reintervention rates based on the primary diagnosis or comorbid mental disorder. Data of the annual trends of SCS use, revision and removal rate of SCS and additional surgical rate after removal was collected and analyzed for patients undergoing SCS between 2007 and 2015, within a private insurance billing database. Trial cases were excluded from this study. The results showed 11,029 patients received SCS implantation with percutaneous electrodes (PE, n = 7418) or surgical electrode (SE, n = 3611). There was a trend of increasing use of SCS from 2007 to 2013, followed by a decrease in last two years. There was no significant difference in the neither removal nor revision rate regardless between the patients with FBSS or CRPS at each time point. Although the removal rates within 2 years were significantly higher in the patients with anxiety disorders compared to the patients without any mental disorders (PE: p < .001, SE: 0.003), the rate of additional surgery after the removal showed no significant difference (PE: p = .532, SE: p = .262). Therefore, we concluded that the primary diagnosis and the presence of anxiety disorders did not have an impact on the additional surgical rate following SCS implantation.

A Novel Lumbar Motion Segment Classification to Predict Changes in Segmental Sagittal Alignment After Lateral Interbody Fixation

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Lateral interbody fixation is being increasingly used for the correction of segmental sagittal parameters. One factor that affects postoperative correction is the resistance afforded by posterior hypertrophic facet joints in the degenerative lumbar spine. In this article, we describe a novel preoperative motion segment classification system to predict postoperative correction of segmental sagittal alignment after lateral lumbar interbody fusion.

METHODS

Preoperative computed tomography scans were analyzed for segmental facet osseous anatomy for all patients undergoing lateral lumbar interbody fusion at 3 institutions. Each facet was assigned a facet grade (min = 0, max = 2), and the sum of the bilateral facet grades was the final motion segment grade (MSG; min = 0, max = 4). Preoperative and postoperative segmental lordosis was measured on standing lateral radiographs. Postoperative segmental lordosis was also conveyed as a percentage of the implanted graft lordosis (%GL). Simple linear regression was conducted to predict the postoperative segmental %GL according to MSG.

RESULTS

A total of 36 patients with 59 operated levels were identified. There were 19 levels with MSG 0, 14 levels with MSG 1, 13 levels with MSG 2, 8 levels with MSG 3, and 5 levels with MSG 4. Mean %GL was 115%, 90%, 77%, 43%, and 5% for MSG 0 to 4, respectively. MSG significantly predicted postoperative %GL (P < .01). Each increase in MSG was associated with a 28% decrease in %GL.

CONCLUSIONS

We propose a novel facet-based motion segment classification system that significantly predicted postoperative segmental lordosis after lateral lumbar interbody fusion.

Kinematic evaluation of cervical sagittal balance and thoracic inlet alignment in degenerative cervical spondylolisthesis using kinematic magnetic resonance imaging

BACKGROUND CONTEXT

T1 slope is a novel thoracic parameter used to assess cervical spine sagittal balance. Thoracic index (TI) parameters including T1 slope and cervical sagittal alignment parameters may play an important role in degenerative cervical spondylolisthesis (DCS). Current literature regarding the relationship between TI and cervical sagittal alignment parameters in patients with DCS is limited.

PURPOSE

(1) To evaluate the T1 slope, cervical sagittal alignment, and thoracic inlet parameter in patients with DCS using kinematic magnetic resonance imaging (kMRI), and (2) to find a correlation between the T1 slope, TI, and other cervical sagittal parameters in patients with DCS.

DESIGN/SETTING

Retrospective kMRI study, Level III.

PATIENT SAMPLE

Fifty-two patients with DCS from 1,128 patients from a cervical kMRI database.

OUTCOME MEASURES

T1 slope, C2-C7 angle, sagittal vertical axis C2-C7 (SVA C2-C7), cranial tilt, cervical tilt, neck tilt, and thoracic inlet angle (TIA).

METHODS

Cervical spine kMRIs of 52 patients with DCS (mean age 51.7±standard deviation) were analyzed in neutral, flexion, and extension positions. Patients with DCS were divided into two groups: anterolisthesis (N=33) and retrolisthesis (N=19). Each listhesis group was subclassified into grade 1 (slip 2-3 mm) and grade 2 (slip>3 mm).

RESULTS

Grade 2 retrolisthesis had the largest T1 slope followed by grade 1 retrolisthesis, grade 2 anterolisthesis, and grade 1 anterolisthesis. Significant differences were found between the anterolisthesis and the retrolisthesis groups in the neutral position (p=.025). The flexion position had the largest T1 slope and showed a significant difference with anterolisthesis in the neutral position (p=.041). Sagittal vertical axis C2-C7 showed strong correlation with cranial tilt in all DCS groups and all positions.

CONCLUSIONS

In our study, T1 slope was larger in grade 2 DCS, and the retrolisthesis group had larger T1 slope than the anterolisthesis group. Presence of larger T1 slope was significantly correlated with larger cervical lordosis curvature. Furthermore, cranial tilt was strongly correlated with SVA C2-C7.

Effect of mental health on postoperative infection rates following cervical spine fusion procedures

PURPOSE

The aim of this study was to determine whether having an existing psychiatric disorder is a risk factor for developing post-operative infection following anterior cervical discectomy with fusion (ACDF) and posterior cervical fusion (PCF).

RESULTS

A total of 34,007 patients within Humana database was included in this study. Patients with mental disorders had post-operative infection rates of 3.2% and 4.4% within 1 and 3months, compared to 2.5% and 3.5% in patients without a psychiatric disorder (p < 0.05).

CONCLUSIONS

Patients with mental disorders had significantly higher rates of post-operative infection compared to patients who were never diagnosed with a psychiatric disorder.

Abstract 139: Deep Sequencing Identifies MicroRNA Let-7 Regulating Cardiomyocyte Apoptosis in a Porcine Model of Early Myocardial Infarction

Myocardial infarction (MI) is a leading cause of mortality and heart failure worldwide. Several animal models have been utilized to mimic human MI. Porcine is considered one of the most representative models. Here, we take advantage of a porcine MI model and next-generation sequencing techniques to discover differential microRNA expression occurring in early MI. We found that microRNAs let-7a and let-7f were enriched in heart tissues and showed significant downregulation within 24 hours post-MI. Inhibition of let-7 by Tough Decoy (TuD) RNA in vivo enhanced cardiomyocyte apoptosis. Overexpression of let-7 downstream target GeneA activated p38 MAPK and led to cardiomyocyte apoptosis. Inhibition of p38 MAPK rescued GeneA induced activation of Caspase 3. We therefore hypothesized that downregulation of let-7 promotes cardiomyocyte death through GeneA and p38 MAPK signaling pathway. In support of this, overexpression of let-7 or inhibition of GeneA reduced p38 MAPK activity and rescued cell death induced by serum starvation in vitro . Finally, we confirmed that in pigs with acute MI, the plasma level of let-7 was significantly reduced and the plasma level of GeneA was significantly increased. This study identifies differential expression of microRNAs in early MI, uncovers the roles of let-7 and GeneA in cardiovascular diseases, and also provides potential biomarkers and therapeutic targets for further investigation.

Risk and Cost of Reoperation After Single-Level Posterior Cervical Foraminotomy: A Large Database Study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To examine the risk of undergoing another cervical spine surgery after single-level posterior cervical foraminotomy (PCF) and analyze the costs of such reoperations.

METHODS

Using the PearlDiver database, we created database algorithms to identify cohorts of patients who underwent single-level PCF and also had various reoperations of interest, within 1, 2, and 4 years of follow-up. We also identified the per-patient average charge (PPAC) for each reoperation cohort.

RESULTS

In the Medicare cohort, the incidence of any reoperation was 8.3%, 9.8%, and 10.5% within 1, 2, and 4 years of follow-up, respectively. The PPAC was $8520 for the initial PCF procedure. When a second cervical surgery was performed, the PPAC was $70 349 for anterior fusion, $15 760 for posterior decompression alone, and $77 976 for posterior decompression and fusion. In the UnitedHealth cohort, the incidence of any reoperation was 13.6%, 16.7%, and 17.0% within 1, 2, and 4 years of follow-up, respectively.

CONCLUSIONS

The overall incidence of another cervical spine operation was slightly higher in the Medicare population to that in previous literature, but much higher in the UnitedHealth population. The most common reoperation after PCF varied between the Medicare and UnitedHealth datasets, and costs varied widely based on the procedure performed. This study provides pertinent information that surgeons can use to discuss the risk of reoperation with their patients.

Minimally invasive L5-S1 oblique lumbar interbody fusion with anterior plate

Lumbar interbody fusion is an important technique for the treatment of degenerative disc disease and degenerative scoliosis. The oblique lumbar interbody fusion (OLIF) establishes a minimally invasive retroperitoneal exposure anterior to the psoas and lumbar plexus. In this video case presentation, the authors demonstrate the techniques of the OLIF at L5-S1 performed on a 69-year-old female with degenerative scoliosis as one component of an overall strategy for her deformity correction. The video can be found here: https://youtu.be/VMUYWKLAl0g .

A Portable Shoulder-Mounted Camera System for Surgical Education in Spine Surgery

The past several years have demonstrated an increased recognition of operative videos as an important adjunct for resident education. Currently lacking, however, are effective methods to record video for the purposes of illustrating the techniques of minimally invasive (MIS) and complex spine surgery. We describe here our experiences developing and using a shoulder-mounted camera system for recording surgical video. Our requirements for an effective camera system included wireless portability to allow for movement around the operating room, camera mount location for comfort and loupes/headlight usage, battery life for long operative days, and sterile control of on/off recording. With this in mind, we created a shoulder-mounted camera system utilizing a GoPro™ HERO3+, its Smart Remote (GoPro, Inc., San Mateo, California), a high-capacity external battery pack, and a commercially available shoulder-mount harness. This shoulder-mounted system was more comfortable to wear for long periods of time in comparison to existing head-mounted and loupe-mounted systems. Without requiring any wired connections, the surgeon was free to move around the room as needed. Over the past several years, we have recorded numerous MIS and complex spine surgeries for the purposes of surgical video creation for resident education. Surgical videos serve as a platform to distribute important operative nuances in rich multimedia. Effective and practical camera system setups are needed to encourage the continued creation of videos to illustrate the surgical maneuvers in minimally invasive and complex spinal surgery. We describe here a novel portable shoulder-mounted camera system setup specifically designed to be worn and used for long periods of time in the operating room.

Postoperative complications in patients undergoing minimally invasive sacroiliac fusion

BACKGROUND CONTEXT

Minimally invasive sacroiliac (SI) joint fusion has become increasingly relevant in recent years as a treatment for SI joint pathology. Previous studies have found minimally invasive SI fusion to be an effective and safe treatment option for chronic SI joint pain. However, these studies have been primarily single-center, case-based, or manufacturer-sponsored investigations, and as such their findings are limited to their sample populations.

PURPOSE

The aim of this study was to investigate the safety of minimally invasive SI fusion using a large nationwide sample group to more accurately identify complication rates of this increasingly popular procedure.

STUDY DESIGN/SETTING

This is a retrospective database study.

PATIENT SAMPLE

The sample includes patients within the orthopedic subset of Humana database who underwent minimally invasive SI fusion between 2007 and 2014.

OUTCOME MEASURES

Complications and novel lumbar and nerve pathology were the outcome measures.

METHODS

Patients undergoing minimally invasive SI fusion from 2007 to 2014 were identified using the Pearl Diver patient record database (Pearl Diver Technologies, West Conshohocken, PA, USA) from the nationwide private insurance provider Humana Inc. This approach provided access to records of over 18 million patients in every major geographic region of the country. Using the ICD-9 diagnosis codes (International Classification of Diseases 9th edition), data from patient records were analyzed to reveal incidence of postoperative infection, pain, osteomyelitis, joint derangement, urinary tract infection, and novel lumbar and nervous system pathology.

RESULTS

Four hundred sixty-nine patients (305 female; 164 male) within the Humana insurance database received minimally invasive SI fusion between 2007 and 2014. Data from these patients showed a substantial increase in the use of the procedure over this 7-year period. Among these patients, an overall complication rate of 13.2% (n=62) was seen at 90 days postoperatively and 16.4% (n=77) at 6 months. The number of patients receiving a first time diagnosis of lumbar pathology following minimally invasive SI fusion in the sample population was also analyzed. The incidence of novel lumbar pathology in this population was 3.6% (n=17) at 90 days postoperatively and 5.3% (n=25) at 6 months. Men experienced diagnoses of novel lumbar pathology at higher rates than women within both 90 days (men=6.7%; women≤3.3%) and 6 months (men=9.1%; women≤3.3%) of the procedure (p<.01).

CONCLUSIONS

The results of this study show that minimally invasive SI joint fusion could possibly carry higher risks of complications than previously stated. These findings are useful for physicians and patients when considering treatment for chronic SI joint pain.

Complications associated with the Dynesys dynamic stabilization system: a comprehensive review of the literature

The Dynesys dynamic stabilization system is an alternative to rigid instrumentation and fusion for the treatment of lumbar degenerative disease. Although many outcomes studies have shown good results, currently lacking is a comprehensive report on complications associated with this system, especially in terms of how it compares with reported complication rates of fusion. For the present study, the authors reviewed the literature to find all studies involving the Dynesys dynamic stabilization system that reported complications or adverse events. Twenty-one studies were included for a total of 1166 patients with a mean age of 55.5 years (range 39-71 years) and a mean follow-up period of 33.7 months (range 12.0-81.6 months). Analysis of these studies demonstrated a surgical-site infection rate of 4.3%, pedicle screw loosening rate of 11.7%, pedicle screw fracture rate of 1.6%, and adjacent-segment disease (ASD) rate of 7.0%. Of studies reporting revision surgeries, 11.3% of patients underwent a reoperation. Of patients who developed ASD, 40.6% underwent a reoperation for treatment. The Dynesys dynamic stabilization system appears to have a fairly similar complication-rate profile compared with published literature on lumbar fusion, and is associated with a slightly lower incidence of ASD.

S-1 and S-2-alar-iliac screw fixation via intraoperative navigation

Adult deformity patients often require fixation to the sacrum and pelvis for construct stability and improved fusion rates. Although certain sacropelvic fixation techniques can be challenging, the availability of intraoperative navigation has made many of these techniques more feasible. In this video case presentation, the authors demonstrate the techniques of S-1 bicortical screw and S-2-alar-iliac screw fixation under intraoperative navigation in a 67-year-old female. This instrumentation placement was part of an overall T-10-pelvis construct for the correction of adult spinal deformity. The video can be found here: https://youtu.be/3HZo-80jQr8 .

Introduction to Lumbosacral and Sacropelvic Fixation Strategies

We are pleased to present this Neurosurgical Focus video supplement on lumbosacral and sacropelvic fixation strategies. Despite advancement in surgical techniques and technologies in spine, achieving consistent solid fusion across the lumbosacral junction remains a major challenge. The anatomy of the lumbosacral junction allows for a higher range of motion compared to other areas of the thoracolumbar spine. The L5-S1 interspace is exposed to significant shear forces. As a result, complications such as pseudoarthrosis, screw pull-out, implant fracture, or sacral fractures can occur. Complications are particularly seen in long fusion constructs ending across the lumbosacral junction. To reduce these complications, various lumbosacral and sacropelvic fixation techniques have been developed and utilized. The current supplement is intended to provide instructional videos that illustrate several current techniques for lumbosacral and sacropelvic fixation. The collection includes techniques for anterior L5-S1 interbody fusion, minimally invasive L5-S1 interbody fusions, lumbosacral pedicle screw placement, sacroiliac fusion, and sacro-alar-iliac screw placement. The authors of the videos in the supplement have provided detailed narration and video illustration to describe the nuances of the various open and minimally invasive techniques for lumbosacral and sacral-pelvic fixation. We are pleased to have such a collection of quality video illustration from experts in the field. It's been our privilege to serve as guest editors for this supplement and we believe that you will enjoy the contents of this supplement.

Effects of fusion and conservative treatment on disc degeneration and rates of subsequent surgery after thoracolumbar fracture

OBJECT

The objective of this study was to compare the incidence of degeneration and need for subsequent fusion surgery between patients who were treated nonsurgically and patients treated with fusion after a diagnosis of thoracic-or lumbar-level fracture without degenerative disease.

METHODS

The authors performed a retrospective study of Orthopedic United Healthcare patients diagnosed with thoracic or lumbar fracture. Patients were filtered into thoracic and lumbar fracture groups using diagnostic codes and then assigned to one of 2 treatment subgroups (fusion surgery or no surgery) on the basis of procedural codes. Disc degeneration and follow-up surgery were recorded. Chi-square statistical analysis was used.

RESULTS

Of 3699 patients diagnosed with a thoracic fracture, 117 (3.2%) underwent thoracic fusion and 3215 (86.9%) were treated nonsurgically. Within 3 years, 147 (4.6%) patients from the nonsurgical subgroup and fewer than 11 (0.9%-8.5%) from the fusion subgroup were diagnosed with thoracic disc degeneration. From the nonsurgical subgroup, 11 (0.3%) patients underwent a thoracic surgery related to disc degeneration compared with zero from the fusion group (p > 0.05). Of 5016 patients diagnosed with lumbar fracture, 150 (3.0%) underwent fusion and 4371 (87.1%) had no surgery. Within 3 years, 503 patients (11.5%) from the nonsurgical subgroup and 35 (23.3%) from the fusion subgroup were diagnosed with lumbar disc degeneration (p < 0.05). From the nonsurgical subgroup, 42 (1.0%) went on to have surgery related to disc degeneration, compared with fewer than 11 (0.7%-6.7%) from the fusion subgroup (values not precise due to privacy limitations).

CONCLUSIONS

Fusion surgery for thoracic fracture does not appear to increase the likelihood of undergoing future surgery. In the lumbar region, initial fusion surgery appears to increase the incidence of disc degeneration and could potentially necessitate future surgeries.

The indications and timing for operative management of spinal epidural abscess: literature review and treatment algorithm

OBJECT

Delayed or inappropriate treatment of spinal epidural abscess (SEA) can lead to serious morbidity or death. It is a rare event with significant variation in its causes, anatomical locations, and rate of progression. Traditionally the treatment of choice has involved emergency surgical evacuation and a prolonged course of antibiotics tailored to the offending pathogen. Recent publications have advocated antibiotic treatment without surgical decompression in select patient populations. Clearly defining those patients who can be safely treated in this manner remains in evolution. The authors review the current literature concerning the treatment and outcome of SEA to make recommendations concerning what population can be safely triaged to nonoperative management and the optimal timing of surgery.

METHODS

A PubMed database search was performed using a combination of search terms and Medical Subject Headings, to identify clinical studies reporting on the treatment and outcome of SEA.

RESULTS

The literature review revealed 28 original case series containing at least 30 patients and reporting on treatment and outcome. All cohorts were deemed Class III evidence, and in all but two the data were obtained retrospectively. Based on the conclusions of these studies along with selected smaller studies and review articles, the authors present an evidence-based algorithm for selecting patients who may be safe candidates for nonoperative management.

CONCLUSIONS

Patients who are unable to undergo an operation, have a complete spinal cord injury more than 48 hours with low clinical or radiographic concern for an ascending lesion, or who are neurologically stable and lack risk factors for failure of medical management may be initially treated with antibiotics alone and close clinical monitoring. If initial medical management is to be undertaken the patient should be made aware that delayed neurological deterioration may not fully resolve even after prompt surgical treatment. Patients deemed good surgical candidates should receive their operation as soon as possible because the rate of clinical deterioration with SEA is notoriously unpredictable. Although patients tend to recover from neurological deficits after treatment of SEA, the time point when a neurological injury becomes irreversible is unknown, supporting emergency surgery in those patients with acute findings.

Outcomes following attempted en bloc resection of cervical chordomas in the C-1 and C-2 region versus the subaxial region: a multiinstitutional experience

Object

Chordomas involving the mobile spine are ideally managed via en bloc resection with reconstruction to optimize local control and possibly offer cure. In the cervical spine, local anatomy poses unique challenges, limiting the feasibility of aggressive resection. The authors present a multi-institutional series of 16 cases of cervical chordomas removed en bloc. Particular attention was paid to clinical outcome, complications, and recurrence. In addition, outcomes were assessed according to position of tumor at the C1–2 level versus the subaxial (SA) spine (C3–7).

Methods

The authors reviewed cases involving patients who underwent en bloc resection of cervical chordoma at 4 large spine centers. Patients were included if the lesion epicenter involved the C-1 to C-7 vertebral bodies. Demographic data and details of surgery, follow-up course, exposure to adjuvant therapy, and complications were obtained. Outcome was correlated with presence of tumor in C1–2 versus subaxial spine via a Student t-test.

Results

Sixteen patients were identified (mean age at presentation 55 ± 14 years). Seven cases (44%) cases involved C1–2, and 16 involved the subaxial spine. Median survival did not differ significantly different between the C1–2 (72 months) and SA (60 months) groups (p = 0.65). A combined (staged anteroposterior) approach was used in 81% of the cases. Use of the combined approach was significantly more common in treatment of subaxial than C1–2 tumors (100% vs 57%, p = 0.04). En bloc resection was attempted via an anterior approach in 6% of cases (C1–2: 14.3%; SA: 0%; p = 0.17) and a posterior approach in 13% of cases (C1–2: 29%; SA: 0%; p = 0.09). The most commonly reported margin classification was marginal (56% of cases), followed by violated (25%) and wide (19%). En bloc excision of subaxial tumors was significantly more likely to result in marginal margins than excision of C1–2 tumors (C1–2: 29%; SA: 78%; p = 0.03). C1–2 tumors were associated with significantly higher rates of postoperative complications (C1–2: 71%; SA: 22%; p = 0.03). Both local and distant tumor recurrence was greatest for C1–2 tumors (local C1–2: 29%; local SA: 11%; distant C1–2: 14%; distant SA: 0%). Statistical analysis of tumor recurrence based on tumor location was not possible due to the small number of cases. There was no between-groups difference in exposure to postoperative adjuvant radiotherapy. There was no difference in median survival between groups receiving proton beam radiotherapy or intensity-modulated radiotherapy versus no radiation therapy (p = 0.8).

Conclusions

Compared with en bloc resection of chordomas involving the subaxial cervical spine, en bloc resection of chordomas involving the upper cervical spine (C1–2) is associated with poorer outcomes, such as less favorable margins, higher rates of complications, and increased tumor recurrence. Data from this cohort do not support a statistically significant difference in survival for patients with C1–2 versus subaxial disease, but larger studies are needed to further study survival differences.

Lower availability of midbrain serotonin transporter between healthy subjects with and without a family history of major depressive disorder - a preliminary two-ligand SPECT study

PURPOSE

Serotonin transporter (SERT) and dopamine transporter (DAT) levels differ in patients with major depressive disorder (MDD) who are in a depressed state in comparison with healthy controls. In addition, a family history of depression is a potent risk factor for developing depression, and inherited vulnerability to serotonergic and dopaminergic dysfunction is suspected in this. The aim of this study was to examine the availabilities of midbrain SERT and striatal DAT in healthy subjects with and without a first-degree family history of MDD.

METHODS

Eight healthy subjects with first-degree relatives with MDD and 16 sex- and age-matched healthy controls were recruited. The availabilities of SERT and DAT were approximated using SPECT, employing [¹²³I] 2-((2-((dimethylamino) methyl) phenyl)thio)-5-iodophenylamine (ADAM) and [(⁹⁹m)Tc] TRODAT-1 as the ligands, respectively. There are missing data for one participant with a first-degree family history of MDD from the ADAM study, due to a lack of the radio-ligand at the time of experiment.

RESULTS

SERT availability in the midbrain was significantly lower in subjects with a first-degree family history of MDD than in healthy subjects. However, DAT availability was no different between two groups.

CONCLUSIONS

The results with regard to the midbrain SERT level suggest the heritability of MDD.