James D. Kang

Establishing objective volume-outcome measures for anterior and posterior cervical spine fusion

OBJECTIVES There is a growing literature on the relationship between provider volume and patient outcomes, specifically within joint arthroplasty and lumbar spine surgery. Such benchmarks have yet to be established for many other spinal procedures, including cervical fusion. We sought to determine whether outcomes-based volume measures for both surgeons and hospitals can be established for cervical spine fusion procedures. PATIENTS AND METHODS This was a retrospective review of patient data in the Florida Statewide Inpatient Dataset (SID; 2011-14). Patients identified in the Florida SID who underwent either anterior or posterior cervical fusion were identified along with the operative surgeons and the hospitals where the procedures were performed. Socio-demographic data, as well as medical and surgical characteristics were obtained, as were the development of complications and readmissions up to 90days following hospital discharge. Surgeon and hospital volume were plotted separately against the number of complications and readmissions in an adjusted spline analysis. Multivariable logistic regression analysis was subsequently performed to assess the effect of surgeon and hospital volume on post-operative complications and readmissions. RESULTS There were 8960 patients with posterior cervical fusion and 57,108 anterior cervical fusions (total=66,068) identified for inclusion in the analysis. The patients of low-volume surgeons were found to have an increased (OR 1.83; 95% CI 1.65, 2.02) likelihood of complications following anterior and posterior (OR 1.45; 95% CI 1.24, 1.69) cervical fusion. Low-volume surgeons demonstrated increased likelihood of readmission, irrespective of anterior (OR 1.37; 95% CI 1.29, 1.47) or posterior (OR 1.31; 95% CI 1.16, 1.48) approach. No clinically meaningful differences in the likelihood of complications or readmissions were detected between high- and low-volume hospitals. CONCLUSIONS This study demonstrates objective volume-outcome measures for surgeons who perform anterior and posterior cervical fusions. Our results have immediate applicability to clinical practice and may be used to benchmark procedural volume. Findings with respect to hospitals speak against the need for healthcare regionalization in this specific clinical context.

The effect of chronic liver disease on acute outcomes following cervical spine trauma

BACKGROUND CONTEXT The adverse impact of chronic liver diseases, including chronic hepatitis and cirrhosis, on outcomes following orthopedic surgery has been increasingly recognized in recent years. The impact of these conditions on acute outcomes following spinal trauma remains unknown. STUDY DESIGN This is a cohort control study that uses patient records in the Massachusetts Statewide Inpatient Dataset (2003-2010). PURPOSE The study aimed to evaluate whether chronic liver disease increased the odds of mortality, complications, failure to rescue (FTR), reoperation, and hospital length of stay (LOS) following cervical spine trauma. PATIENT SAMPLE The sample is composed of 10,841 patients with cervical spine trauma. OUTCOME MEASURES Posttreatment morbidity, mortality, reoperation, and LOS were the outcome measures. METHODS Differences between patients with and without chronic liver disease were evaluated using chi-square or Wilcoxon rank-sum tests. Logistic and negative binomial regression techniques were used to adjust for confounders, including whether a surgical intervention was performed. Receiver operator characteristic curves were used to assess final model discrimination. RESULTS There were 117 patients with chronic liver disease identified in the cohort. The rate of surgical intervention for cervical trauma was not significantly different between patients with and without chronic liver disease (odds ratio [OR]: 0.82, 95% confidence interval [CI]: 0.52-1.29). Mortality (OR: 2.12, 95% CI: 1.23-3.66), FTR (OR: 2.86, 95% CI: 1.34-6.11), complications (OR: 1.65, 95% CI: 1.12-2.45), and LOS (regression coefficients: 0.31, 95% CI: 0.14-0.48) were all significantly increased for patients with chronic liver disease in final adjusted models that controlled for differences in case-mix and whether a surgical procedure was performed. Final models explained approximately 72% of the variation in mortality and FTR. CONCLUSIONS Our novel findings indicate that patients with chronic liver disease may be at elevated risk of posttreatment morbidity and mortality following cervical spine trauma. Medical comanagement in the acute period following injury and optimization before surgery may diminish the potential for adverse events.

NF-κB Signaling Pathway in Controlling Intervertebral Disk Cell Response to Inflammatory and Mechanical Stressors

Background Intervertebral disk degeneration (IDD) has a greater than 90% lifetime incidence and is one of the leading causes of chronic back pain in the United States. Despite the high societal cost of IDD, there is limited understanding of the biological effects of mechanical overloading on further degeneration. The transcription factor NF-κB (nuclear factor κB) has been implicated as a key mediator of disk cell response to inflammatory and mechanical stresses and represents a potential control point. Objective The study objective was to measure the effect of NF-κB signaling pathway inhibition on annulus fibrosus (AF) cell matrix synthesis and gene expression under conditions of combined inflammatory and mechanical stimulation. Methods Annulus fibrosus cells were harvested from rabbit intervertebral disks and grown in vitro on flexible plates. The cells were exposed to inflammatory and mechanical stimulation for 24 hours with and without NF-κB inhibition. Nuclear translocation of NF-κB was measured via immunofluorescent staining. Intervertebral disk cell homeostasis was assessed via inflammatory, anabolic, and catabolic gene expression and via matrix synthetic ability. Results NF-κB nuclear translocation in response to interleukin-1 beta (IL-1β) was reversed with exposure to NF-κB inhibition. NF-κB inhibition decreased matrix metalloproteinase-3, inducible nitric oxide synthase, and cyclooxygenase-2 gene expression and prostaglandin E2 production response to combined inflammatory and mechanical stimulation. Proteoglycan and collagen synthesis were decreased by combined stimulation, but this effect was not reversed by NF-κB inhibition. Limitations In vitro modeling of conditions within the disk may not fully reflect the response that AF cells have in native matrix. Conclusions NF-κB signaling mediates catabolic and inflammatory responses to inflammatory and mechanical stimulation but does not mediate the decrease in matrix synthesis under combined harmful stimulation. Identification of key control points in the cellular responses to inflammatory and mechanical stimuli will facilitate rational design of exercise-based therapies and facilitate synergistic treatments of novel biochemical treatments with rehabilitation regimens.

New horizons in spine research: Intervertebral disc repair and regeneration.

James C. Iatridis, James Kang, Rita Kandel, Makarand V. Risbud Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York 10029, Department of Orthopedic Surgery, Brigham and Women’s Hospital, Boston, Massachusetts 02115, Department of Pathology and Laboratory Medicine, Sinai Health System, Toronto, Ontario M5G1X5, Canada, Department of Orthopaedic Surgery, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107

New Horizons in Spine Research: Disc biology, spine biomechanics and pathomechanisms of back pain

Low back pain and neck pain are the first and fourth leading causes of years lived with disability, respectively.1 The widespread prevalence of back pain makes it among the most costly heathcare conditions, yet, it is surprisingly not among the top ten health conditions receiving research funding.2 This funding discrepancy was noted by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) with a Roundtable on the Role of Disc Degeneration in Neck and Back Pain highlighting the need for novel research and partnerships to overcome some of these challenges.3 To advance novel spine science and collaborations, the 3rd International Spine Research Symposium, co-sponsored by the Philadelphia Spine Research Society (PSRS), NIAMS/NIH and the Orthopaedic Research Society (ORS), was held to enhance understanding of the clinical problems associated with degenerative disc disease, and to highlight cutting-edge scientific research in areas of basic biology, epidemiology, disease mechanisms, biomechanics, tissue engineering and imaging of the intervertebral disc (IVD).4 This special issue on ‘New Horizons in Spine Research’ and a second issue to follow at a later date are outcomes from that meeting, with articles selected from the strong response to the ‘call for papers’. This issue focuses on the fundamental topics of disc ageing and cell biology, spine biomechanics, anatomy and imaging, and pathomechanisms of spine pain. A second special issue will focus on repair and regeneration. This growing passion for advancing spine research and improving spinal health has ignited the spine research community to coalesce within the Orthopaedic Research Society as the newly formed Spine Section (http://www.ors.org/spinesection/) in order to enhance communication and collaboration.

Alterations in 90-day morbidity, mortality, and readmission rates following spine surgery in Medicare Accountable Care Organizations (2009–2014)

BACKGROUND CONTEXT The impact of Accountable Care Organizations (ACOs) on healthcare quality and outcomes, including morbidity, mortality, and readmissions, has not been substantially investigated, especially following spine surgery. PURPOSE To evaluate the impact of ACO formation on postoperative outcomes in the 90-day period following spine surgery. STUDY DESIGN Retrospective review of national Medicare claims data (2009-2014). PATIENT SAMPLE Patients who underwent one of four lumbar spine surgical procedures in an ACO or non-ACO. OUTCOME MEASURES The development of in-hospital mortality, complications or hospital readmission within 90 days of the surgical procedure. METHODS The primary outcome measures included postsurgical complications and readmissions at 90 days following surgery. In-hospital mortality and 30-day outcomes were considered secondarily. The primary predictor variable consisted of ACO enrollment designation. Multivariable logistic regression analysis was utilized to adjust for confounders and determine the independent effect of ACO enrollment on postsurgical outcomes. The multivariable model included a propensity score adjustment that accounted for factors associated with the preferential enrollment of patients in ACOs, namely, sociodemographic characteristics, medical co-morbidities, hospital teaching status, bed size, and location. RESULTS In all, there were 344,813 patients identified for inclusion in this analysis with 97% (n = 332,890) treated in non-ACOs and 3% (n = 11,923) in an ACO. Although modest changes were apparent across both ACOs and non-ACOs over the time-period studied, improvements were slightly more dramatic in non-ACOs leading to statistically significant differences in both 90-day complications and readmissions. Specifically, in the period 2012-2014, ACOs demonstrated an 18% increase in the odds of 90-day complications and a 14% elevation in the odds of 90-day readmissions when compared to non-ACOs. There was no difference in hospital mortality between ACOs and non-ACOs. CONCLUSIONS Our study of Medicare data from 2009 to 2014 failed to demonstrate superior reductions in postoperative morbidity, mortality, and readmissions for beneficiaries treated in ACOs as compared to non-ACOs. These results indicate that meaningful changes in postoperative outcomes should not be anticipated based on organizational participation in ACOs at present.

Molecular Mechanisms of Intervertebral Disc Degeneration

Intervertebral disc degeneration is a well-known cause of disability, the result of which includes neck and back pain with associated mobility limitations. The purpose of this article is to provide an overview of the known molecular mechanisms through which intervertebral disc degeneration occurs as a result of complex interactions of exogenous and endogenous stressors. This review will focus on some of the identified molecular changes leading to the deterioration of the extracellular matrix of both the annulus fibrosus and nucleus pulposus. In addition, we will provide a summation of our current knowledge supporting the role of associated DNA and intracellular damage, cellular senescences catabolic effects, oxidative stress, and the cells inappropriate response to damage in contributing to intervertebral disc degeneration. Our current understanding of the molecular mechanisms through which intervertebral disc degeneration occurs provides us with abundant insight into how physical and chemical changes exacerbate the degenerative process of the entire spine. Furthermore, we will describe some of the related molecular targets and therapies that may contribute to intervertebral repair and regeneration.

Cervical Radiculopathy and Myelopathy

Cervical radiculopathy is a symptomatic root dysfunction that is most often self-limiting. Familiarity with cervical spine anatomy and the clinical presentation of root dysfunction help to make the diagnosis. Activity modification, anti-inflammatory medications, and physical therapy are often adequate in managing symptoms. Surgical consultation is warranted for persistent or debilitating symptoms and in the setting of motor weakness. Cervical myelopathy is the result of spinal cord dysfunction, most commonly due to compressive, degenerative pathology. A detailed history, physical examination, and appropriate neuroradiographic imaging are used to make the diagnosis. An understanding of its stepwise, progressive natural history, and the offending structural abnormality, is key to helping patients make informed care decisions.

Reoperation of decompression alone or decompression plus fusion surgeries for degenerative lumbar diseases: a systematic review

AbstractPurposeThe objective of this paper was to compare the reoperation rates, timing and causes between decompression alone and decompression plus fusion surgeries for degenerative lumbar diseases through a systematic review of the published data. MethodsA search of the literature was conducted on PubMed/MEDLINE, EMBASE and the Cochrane Collaboration Library. Reports that included reoperations after decompression alone and/or decompression plus fusion surgeries were selected using designed eligibility criteria. Comparative analysis of reoperation rates, timing and causes between the two surgeries was conducted.ResultsThirty-two retrospective and three prospective studies were selected from 6401 papers of the literature search. The analysis of data reported in these studies revealed that both surgeries resulted in similar reoperation rates after the primary surgery. However, majority of reoperations following the fusion surgeries were due to adjacent-segment diseases, and following the decompression alone surgeries were due to the same-segment diseases. Reoperation rates were not found to decrease in patients operated more recently than those operated in early times.ConclusionsReoperation rates were similar following decompression alone or plus fusion surgeries for degenerative lumbar diseases. However, different underlying major causes exist between the two surgeries. There is no evidence showing that the reoperation rate has a trend to decline with newer surgical techniques used. The exact mechanisms of reoperation after both surgeries are still unclear. Further researches are necessary to investigate the mechanisms of reoperation for improvement of surgical techniques that aim to delay or prevent reoperation after lumbar surgery.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.