Disk degeneration and low back pain: are they fat-related conditions?

Does Body Mass Index Influence Intraoperative Costs and Operative Times for Anterior Cervical Discectomy and Fusion? A Time-Driven Activity-Based Costing Analysis

OBJECTIVE

Spine surgeons are often unaware of drivers of cost variation for anterior cervical discectomy and fusion (ACDF). We used time-driven activity-based costing to assess the relationship between body mass index (BMI), total cost, and operating room (OR) times for ACDFs.

METHODS

Total cost was divided into direct and indirect costs. Individual costs were obtained by direct observation, electronic medical records, and through querying multiple departments. Timestamps for all involved personnel and material resources were documented. Total intraoperative costs were estimated for all ACDFs from 2017 to 2022. All patients were categorized into distinct BMI-based cohorts. Linear regression models were performed to assess the relationship between BMI, total cost, and OR times.

RESULTS

A total of 959 patients underwent ACDFs between 2017 and 2022. The average age and BMI were 58.1 ± 11.2 years and 30.2 ± 6.4 kg/m2, respectively. The average total intraoperative cost per case was $7120 ± $2963. Multivariable regression analysis revealed that BMI was not significantly associated with total cost (P = 0.36), supply cost (P = 0.39), or personnel cost (P = 0.20). Higher BMI was significantly associated with increased time spent in the OR (P = 0.018); however, it was not a significant factor for the duration of surgery itself (P = 0.755). Rather, higher BMI was significantly associated with nonoperative OR time (P < 0.001).

CONCLUSIONS

Time-driven activity-based costing is a feasible and scalable methodology for understanding the true intraoperative costs of ACDF. Although higher BMI was not associated with increased total cost, it was associated with increased preparatory time in the OR.

Obesity in rheumatological practice

Obesity is a chronic disease that leads to the development of secondary metabolic disturbances and diseases and strongly contributes to increased morbidity and mortality. On the other hand, musculoskeletal disorders are currently the main cause of disability and the second most frequent reason for visits to the doctor. Many studies clearly show that excessive body weight adversely affects the course of almost all musculoskeletal system diseases, from osteoarthritis, through metabolic, systemic connective tissue, to rarely diagnosed diseases. The impact of increased fat mass on the musculoskeletal system is presumably complex in nature and involves the influence of biomechanical, dietary, genetic, inflammatory and metabolic factors. Due to the epidemic nature of obesity and its serious health consequences, this disease requires energetic treatment. It is always based on lifestyle modification enriched, if necessary, by pharmacological and, in justified cases, surgical treatment.

Subjective assessment and biochemical evaluation of traction therapy in women with chronic low back pain: does body mass index matter? A clinical study

BACKGROUND

Apart from the positive effect of lumbar traction on structural changes within the spine in patients with low back pain, it is likely that therapeutic effects are correlated with pain biomarkers in the blood. Among them, systemic metabolic factors related to obesity may play an important role. This is the first study designed to examine the effectiveness of traction therapy in two experimental groups with considerably different BMI and to assess relationships between blood biomarkers and low back pain intensity.

METHODS

In the prospective clinical trial, women suffering from chronic low back pain were allocated into the normal-weight or obesity groups. Patients in both groups underwent twenty sessions of lumbar traction therapy (30 min a day, continuous mode with a force level of 25-30% of body weight). Before and after therapy subjective assessments of pain (VAS and PPT) were performed, and serum concentrations of aggrecan chondroitin sulfate 846 epitope (CS-846), neuropeptide Y, leptin, adipsin and growth and differentiation factor 15 (GDF-15) were determined. The data were statistically evaluated for 28 women.

RESULTS

After therapy, the maximal low back pain decreased in both groups, GDF-15 concentration was reduced in the normal-weight group and increased in the obesity group, and CS-846 concentration decreased in the obesity group. The sensation of PPT in the lumbar spine and mean concentrations of neuropeptide Y, leptin and adipsin did not change in both groups. However, the relationships of GDF-15, leptin, and adipsin concentrations with the perception of pain were revealed.

CONCLUSION

Distinct differences between the normal-weight and obesity groups pointed on the role of excessive adipose tissue in aggravating the inflammatory processes and in the development of low back pain. Adipsin, CS-846 and GDF-15 aspire to be the low back pain biomarkers in women with obesity, but there is a need for further research to answer whether they might be considered reliable biomarkers for the prognosis and monitoring of chronic low back treatment.

TRIAL REGISTRATION

NCT04507074, registered prospectively on July 6, 2020.

The Effect of Intraabdominal Visceral and Subcutaneous Adipose Volume and Muscle Volume on Lumbar Vertebrae Degeneration

OBJECTIVES

This study aimed to investigate the effect of the volume of subcutaneous, visceral, and total adipose tissue, and paravertebral muscles in patients with lumbar vertebrae degeneration (LVD) through computerized tomography (CT) images.

MATERIALS AND METHODS

One forty-six patients with a complaint of lower back pain (LBP) between January 2019 and December 2021 were included in the study. CT scans of all patients were analyzed retrospectively for abdominal visceral, subcutaneous, and total fat volume, and also paraspinal muscle volume measurements and analysis of lumbar vertebrae degeneration (LVD) using designated software. In CT images, each intervertebral disc space was evaluated in terms of the presence of osteophytes, loss of disc height, sclerosis in the end plates, and spinal stenosis to investigate the presence of degeneration. Each level was scored according to the presence of findings, with 1 point for each finding. The total score at all levels (L1-S1) was calculated for each patient.

RESULTS

An association was observed between the loss of intervertebral disc height and the amount of visceral, subcutaneous, and total fat volume at all lumbar levels (p˂0.05). The amount of all fat volume measurements also showed association with osteophyte formation (p˂0.05). An association was found between sclerosis and the amount of all fat volume at all lumbar levels (p˂0.05). It was observed that spinal stenosis at the lumbar levels was not associated with the amount of fat (total, visceral, subcutaneous) at any level (p˃0.05). No association was found between the amount of adipose and muscle volumes and vertebral pathologies at any level (p˃0.05).

CONCLUSION

The abdominal visceral, subcutaneous, and total fat volumes are associated with lumbar vertebral degeneration and loss of disc height. Paraspinal muscle volume does not show an association with vertebral degenerative pathologies.

Evaluation of health related quality of life with the use of Oswestry disability index in degenerative discogenic low back pain

Background

Intervertebral disc degeneration (IVD) is a main underlying cause for low back pain (LBP). Oswestry Disability Index (ODI) is a valuable tool used to measure patient’s low back functional outcome. Our aim is to evaluate the relation between clinical assessment of LBP and health related quality of life with the use of ODI and magnetic resonance image (MRI) findings in patients with degenerative prolapsed IVD disease.

Result

There was a significant correlation between Pfirrmann grades and ODI (p < 0.0001) and with type of disc morphology mostly protrusion (p < 0.0001) but insignificant correlation with visual analogue scale (VAS) (p = 0.198) and most of the clinical parameters (p > 0.05). There was a significant correlation between ODI and VAS (p = 0.003). Higher Pfirrmann grades were found at lower lumbosacral levels L4-5 and L5-S1.

Conclusion

Higher Pfirrmann grades correlated with the increased ODI. No association was found between MRI grading in lumbosacral spine with pain intensity and most of the clinical parameters among persons with discogenic LBP. Chronic LBP is widely accepted to be a multifactorial disorder that could not be contained within a single lumbar compartment. Clinician should not depend on MRI findings only in the diagnosis. History from the patient and clinical examination is particularly important to reach the final diagnosis. ODI might be convenient in achieving patient’s confidence and decreasing unnecessary investigations.

The Impact of Prior Bariatric Surgery on Outcomes After Spine Surgery: A Systematic Review and meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

To compare outcomes and complication rates in patients undergoing bariatric surgery (BS) prior to spine surgery.

METHODS

A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines comparing the outcomes of spine surgery between subjects with prior bariatric surgery to those who were considered obese with no prior bariatric surgery.

RESULTS

A total of 183, 570 patients were included in the 4 studies meeting inclusion criteria. The mean patient age was 52.9 years, and the majority were female (68%). The two groups consisted of a total of 36, 876 patients with prior BS and 146, 694 obese patients without prior BS. The overall rate of complications in the prior BS group was 6.4% (4.5%-38.7%) compared to 11.9% (11.2%-55.4%) in the non-prior BS obese group with a statistically significant difference between the two groups. The prior BS group had lower rates of renal, neurological, and thromboembolic complications, with a lower mortality and readmission rate. In a subgroup undergoing cervical spine surgery, patients with prior BS had fewer cardiac, GI, and total complications. For patients undergoing thoracolumbar spine surgery, patients with prior BS had fewer thromboembolic and total complications.

CONCLUSION

Patients undergoing bariatric surgery prior to spine surgery had fewer renal, neurological, and thromboembolic complications as well as a decreased mortality and readmission rate.

Sulphurous Crenotherapy Is Effective at Reducing Pain and Disability in Overweight/Obese Patients Affected by Chronic Low Back Pain from Spine Osteoarthritis

Crenotherapy is recognized as being effective in patients with osteoarthritis of the spine, but to date there is no indication if it is effective for patients who are overweight or obese. The aim of this study is to evaluate the efficacy of sulphurous crenotherapy on pain and disability in overweight/obese subjects affected by chronic low back pain from spine osteoarthritis. Forty-three patients (63 ± 8.8 years) affected by chronic low back pain from lumbar spine osteoarthritis were enrolled in this study. Subjects were treated with 2 weeks of sulphurous creno-treatments. Subjective pain was measured by a numerical rating scale score (NRS), and functional mobility of the lumbar spine was measured using the Oswestry Disability Index (ODI) before and after crenotherapy. Both crenotherapy groups (normal weight: A1; overweight/obese: A2) experienced significantly improved NRS and ODI scores (A1: p < 0.001 and p = 0.001; A2: p = 0.001 and p = 0.001). At end of the treatment, significant improvements were observed as a result of the crenotherapy in overweight/obese subjects in terms of pain reduction measured with NRS (p = 0.03) and in terms of function mobility of the lumbar spine measured with ODI (p = 0.006). This study highlights the beneficial effect of sulphurous crenotherapy on the painful symptomatology and disability in both normal weight and overweight/obese patients suffering from chronic low back pain associated with lumbar spine osteoarthritis.

Underweight patients are the highest risk body mass index group for perioperative adverse events following stand-alone anterior lumbar interbody fusion

BACKGROUND CONTEXT

Prior studies investigating the association between Body Mass Index (BMI) and patient outcomes following spine surgery have had inconsistent conclusions, likely owing to insufficient power, confounding variables, and varying definitions and cutoffs for BMI categories (eg, underweight, overweight, obese, etc.). Further, few studies have considered outcomes among low BMI cohorts.

PURPOSE

The current study analyzes how anterior lumbar interbody fusion (ALIF) perioperative outcomes vary along the BMI spectrum, using World Health Organization (WHO) categories of BMI.

STUDY DESIGN/SETTING

A retrospective cohort study.

PATIENT SAMPLE

Patients undergoing stand-alone one or two-level anterior lumbar interbody fusion (ALIF) found in the 2005-2018 American College of Surgeons National Surgical Quality Improvement Program (NSQIP) databases.

OUTCOME MEASURES

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

METHODS

Stand-alone one or two-level ALIF surgical cases were identified and extracted from the 2005-2018 National Surgical Quality Improvement Program (NSQIP) database. Posterior cases and those primary diagnoses of trauma, tumor, infection, or emergency presentation were excluded. Patients were then binned into WHO guidelines of BMI. The incidence of adverse outcomes within 30-day post-operation was defined. Odds ratios of adverse outcomes, normalized to the average risk of normal-weight subjects (BMI 18.5-24.9 kg/m³), were calculated. Multivariate analysis was then performed controlling for patient factors.

RESULTS

In total, 13,710 ALIF patients were included in the study. Incidence of adverse events was elevated in both the underweight (BMI<18.5 kg/m³) and super morbidly obese (>50 kg/m³), however, multivariate risks for adverse events and postoperative infection were elevated for underweight patients beyond those found in any other BMI category. No effect was noted in these identical variables between normal, overweight, obese class 1, or even obese class 2 patients. Multivariate analysis also found overweight patients to show a slightly protective trend against mortality while the super morbidly obese had elevated odds.

CONCLUSIONS

Underweight patients are at greater odds of experiencing postoperative adverse events than normal, overweight, obese class 1, or even obese class 2 patients. The present study identifies underweight patients as an at-risk population that should be given additional consideration by health systems and physicians, as is already done for those on the other side of the BMI spectrum.

In vivo Mouse Intervertebral Disc Degeneration Models and Their Utility as Translational Models of Clinical Discogenic Back Pain: A Comparative Review

Low back pain is a leading cause of disability worldwide and studies have demonstrated intervertebral disc (IVD) degeneration as a major risk factor. While many in vitro models have been developed and used to study IVD pathophysiology and therapeutic strategies, the etiology of IVD degeneration is a complex multifactorial process involving crosstalk of nearby tissues and systemic effects. Thus, the use of appropriate in vivo models is necessary to fully understand the associated molecular, structural, and functional changes and how they relate to pain. Mouse models have been widely adopted due to accessibility and ease of genetic manipulation compared to other animal models. Despite their small size, mice lumbar discs demonstrate significant similarities to the human IVD in terms of geometry, structure, and mechanical properties. While several different mouse models of IVD degeneration exist, greater standardization of the methods for inducing degeneration and the development of a consistent set of output measurements could allow mouse models to become a stronger tool for clinical translation. This article reviews current mouse models of IVD degeneration in the context of clinical translation and highlights a critical set of output measurements for studying disease pathology or screening regenerative therapies with an emphasis on pain phenotyping. First, we summarized and categorized these models into genetic, age-related, and mechanically induced. Then, the outcome parameters assessed in these models are compared including, molecular, cellular, functional/structural, and pain assessments for both evoked and spontaneous pain. These comparisons highlight a set of potential key parameters that can be used to validate the model and inform its utility to screen potential therapies for IVD degeneration and their translation to the human condition. As treatment of symptomatic pain is important, this review provides an emphasis on critical pain-like behavior assessments in mice and explores current behavioral assessments relevant to discogenic back pain. Overall, the specific research question was determined to be essential to identify the relevant model with histological staining, imaging, extracellular matrix composition, mechanics, and pain as critical parameters for assessing degeneration and regenerative strategies.

Risk factors for low back pain outcome: Does it matter when they are measured?

BACKGROUND

The early identification of factors that increase risk of poor recovery from acute low back pain (LBP) is critical to prevent the transition to chronicity. Although most studies of risk factors for poor outcome in LBP tend to investigate the condition once it is already persistent, there is evidence to suggest that this differs from risk factors measured during the early-acute stage. This study aimed to identify early risk factors for poor outcome in the short- and long-term in individuals with acute LBP, and to compare this with factors identified at 3 months in the same cohort.

METHODS

One hundred and thirty-three individuals were recruited within 2 weeks of an acute LBP episode and completed questionnaires related to their sociodemographic, psychological, clinical and history/treatment status at baseline and 3 months later, and their pain-level fortnightly for 12 months.

RESULTS

Of the 133 participants recruited, follow-up data was provided by 120 at 3 months, 97 at 6 months, 85 at 9 months and 94 at 12 months. Linear regression identified various factors at baseline (acute phase) and 3 months later that predicted short- and long-term outcome (pain level, change in pain). Key findings were that: (1) depressive symptoms at baseline most consistently predicted worse outcome; (2) psychological factors in general at 3 months were more predictive of outcome than when measured at baseline; (3) early health care utilisation predicted better outcome, whereas use of pain medication later (3 months) predicted worse outcome; and (4) sex and BMI predicted outcome inconsistently over 12-months.

CONCLUSIONS

The results highlight the multidimensional nature of risk factors for poor outcome in LBP and the need to consider time variation in these factors.

Cervical alignment in the obese population following posterior cervical fusion for cervical myelopathy

STUDY DESIGN

Retrospective cohort study OBJECTIVE: The aim of this study was to investigate the effect of body mass index (BMI) on the reoperation rate and cervical sagittal alignment of patients who underwent posterior cervical decompression and fusion for cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA

Cervical sagittal balance has been correlated with postoperative clinical outcomes. Previous studies have shown worse postoperative sagittal alignment and higher reoperation rates in patients with high BMI undergoing anterior decompression and fusion. Similar evidence for the impact of obesity in postoperative sagittal alignment for patients with (CSM) undergoing posterior cervical decompression and fusion (PCF) is lacking.

METHODS

A retrospective analysis of 198 patients who underwent PCF for cervical myelopathy due to degenerative spine disease was performed. Demographics, need for reoperation, and perioperative radiographic parameters were collected. Cervical lordosis (CL), C2-7 sagittal vertical axis (SVA), and T1 slope (T1S) was measured on standing lateral radiographs. Comparative analysis of the patient cohort was performed by stratifying the sample population into three BMI categories (<25, 25-30, ≥30).

RESULT

Of the 198 patients that met inclusion criteria, 53 had BMI normal (<25), 65 were overweight (25-30), and 80 were obese (≥30). Mean SVA increased postoperatively in all groups, 4 mm in the normal group, 13 mm in the overweight group, and 13 mm in the obese group (p = 0.003). There was no significant difference in the postoperative change of cervical lordosis or T1 slope between the groups. Multivariate analysis demonstrated fusions involving the cervicothoracic junction and those involving 5 or more levels significantly affected alignment parameters. There were 27 complications requiring reoperation (14%) with no significant differences among the groups stratified by BMI (p = 0.386).

CONCLUSIONS

Overweight patients (BMI>25) with CSM undergoing PCF had a greater increase in SVA than normal weight patients while reoperation rates were similar. In addition, preoperative CL increased with increasing BMI, although this trend was not Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation significant and there was not found to be a significant difference between the change in CL from baseline to post-fusion between BMI cohorts. This study further highlights the importance of considering BMI when attempting to optimize sagittal alignment in patients undergoing PCF.

Melatonin Moderates the Triangle of Chronic Pain, Sleep Architecture and Immunometabolic Traffic

Preclinical as well as human studies indicate that melatonin is essential for a physiological sleep state, promotes analgesia and is involved in immunometabolic signaling by regulating neuroinflammatory pathways. Experimental and clinical neuromodulation studies for chronic pain treatment suggest that neurostimulation therapies such as spinal cord stimulation, vagus nerve stimulation and dorsal root ganglion stimulation have an impact on circulating inflammatory mediators in blood, cerebrospinal fluid and saliva. Herein, we provide an overview of current literature relevant for the shared pathways of sleep, pain and immunometabolism and elaborate the impact of melatonin on the crossroad of sleep, chronic pain and immunometabolism. Furthermore, we discuss the potential of melatonin as an adjunct to neurostimulation therapies. In this narrative review, we addressed these questions using the following search terms: melatonin, sleep, immunometabolism, obesity, chronic pain, neuromodulation, neurostimulation, neuroinflammation, molecular inflammatory phenotyping. So far, the majority of the published literature is derived from experimental studies and studies specifically assessing these relationships in context to neurostimulation are sparse. Thus, the adjunct potential of melatonin in clinical neurostimulation has not been evaluated under the umbrella of randomized-controlled trials and deserves increased attention as melatonin interacts and shares pathways relevant for noninvasive and invasive neurostimulation therapies.

Does minimally invasive spine surgery improve outcomes in the obese population? A retrospective review of 1442 degenerative lumbar spine surgeries

OBJECTIVE

The effect of obesity on outcomes in minimally invasive surgery (MIS) approaches to posterior lumbar surgery is not well characterized. The authors aimed to determine if there was a difference in operative variables and complication rates in obese patients who underwent MIS versus open approaches in posterior spinal surgery, as well as between obese and nonobese patients undergoing MIS approaches.

METHODS

A retrospective review of all consecutive patients who underwent posterior lumbar surgery from 2013 to 2016 at a single institution was performed. The primary outcome measure was postoperative complications. Secondary outcome measures included estimated blood loss (EBL), operative time, the need for revision, and hospital length of stay (LOS); readmission and disposition were also reviewed. Obese patients who underwent MIS were compared with those who underwent an open approach. Additionally, obese patients who underwent an MIS approach were compared with nonobese patients. Bivariate and multivariate analyses were carried out between the groups.

RESULTS

In total, 423 obese patients (57.0% decompression and 43.0% fusion) underwent posterior lumbar MIS. When compared with 229 obese patients (56.8% decompression and 43.2% fusion) who underwent an open approach, patients in both the obese and nonobese groups who underwent MIS experienced significantly decreased EBL, LOS, operative time, and surgical site infections (SSIs). Of the nonobese patients, 538 (58.4% decompression and 41.6% fusion) underwent MIS procedures. When compared with nonobese patients, obese patients who underwent MIS procedures had significantly increased LOS, EBL, operative time, revision rates, complications, and readmissions in the decompression group. In the fusion group, only LOS and disposition were significantly different.

CONCLUSIONS

Obese patients have poorer outcomes after posterior lumbar MIS when compared with nonobese patients. The use of an MIS technique can be of benefit, as it decreased EBL, operative time, LOS, and SSIs for posterior decompression with or without instrumented fusion in obese patients.

Intradural Disc Herniation in the Setting of Congenital Lumbar Spinal Stenosis

INTRODUCTION

Accounting for an estimated 1.10-1.76% of all lumbar herniations, lumbar intradural disc herniation (IDH) occurs primarily in males during the fourth to fifth decades of life. While not validated, congenital lumbar spinal stenosis (CLSS) is implicated as one precipitating factor for IDH.

CASE REPORT

We report 28-year-old Hispanic female with CLSS, severe obesity, and degenerative disk disease, with a history of minimally invasive surgical (MIS) decompression for a large paracentral L4-5 disc herniation at 25. After three years, the patient developed sudden burning dysesthesias in the L4-5 dermatomes bilaterally and temporary leg weakness. Lumbar magnetic resonance imaging exhibited severe L4-5 spinal stenosis, and the patient underwent repeat MIS decompression, which again provided her with adequate symptom resolution. However, 20 days postoperatively she developed cauda equina syndrome with anal dysfunction, and bilateral leg and foot weakness. Upon open surgical exploration we discovered a tense L4-5 dural protrusion. After a dorsal durotomy, a large IDH with a ventral dural tear was identified. Subsequent to adequate debulking of the IDH, the ventral tear was repaired, and an expansile duraplasty was performed. Overall, the patient's bladder and bowel function, pain, hypoesthesia, and motor strength all improved. Two weeks after surgery she presented with a lumbar pseudomeningocele that was managed conservatively.

CONCLUSION

This report not only highlights an atypical presentation of IDH and is the first case of CLSS linked with IDH, lending support to the hypothesis that CLSS can lead to IDH, but also provides a comprehensive review of IDHs.

Pathomechanism and Biomechanics of Degenerative Disc Disease: Features of Healthy and Degenerated Discs

The human intervertebral disc (IVD) is a complex organ composed of fibrous and cartilaginous connective tissues, and it serves as a boundary between 2 adjacent vertebrae. It provides a limited range of motion in the torso as well as stability during axial compression, rotation, and bending. Adult IVDs have poor innate healing potential due to low vascularity and cellularity. Degenerative disc disease (DDD) generally arises from the disruption of the homeostasis maintained by the structures of the IVD, and genetic and environmental factors can accelerate the progression of the disease. Impaired cell metabolism due to pH alteration and poor nutrition may lead to autophagy and disruption of the homeostasis within the IVD and thus plays a key role in DDD etiology. To develop regenerative therapies for degenerated discs, future studies must aim to restore both anatomical and biomechanical properties of the IVDs. The objective of this review is to give a detailed overview about anatomical, radiological, and biomechanical features of the IVDs as well as discuss the structural and functional changes that occur during the degeneration process.

Diet-induced obesity leads to behavioral indicators of pain preceding structural joint damage in wild-type mice

Introduction

Obesity is one of the largest modifiable risk factors for the development of musculoskeletal diseases, including intervertebral disc (IVD) degeneration and back pain. Despite the clinical association, no studies have directly assessed whether diet-induced obesity accelerates IVD degeneration, back pain, or investigated the biological mediators underlying this association. In this study, we examine the effects of chronic consumption of a high-fat or high-fat/high-sugar (western) diet on the IVD, knee joint, and pain-associated outcomes.

Methods

Male C57BL/6N mice were randomized into one of three diet groups (chow control; high-fat; high-fat, high-sugar western diet) at 10 weeks of age and remained on the diet for 12, 24, or 40 weeks. At endpoint, animals were assessed for behavioral indicators of pain, joint tissues were collected for histological and molecular analysis, serum was collected to assess for markers of systemic inflammation, and IBA-1, GFAP, and CGRP were measured in spinal cords by immunohistochemistry.

Results

Animals fed obesogenic (high-fat or western) diets showed behavioral indicators of pain beginning at 12 weeks and persisting up to 40 weeks of diet consumption. Histological indicators of moderate joint degeneration were detected in the IVD and knee following 40 weeks on the experimental diets. Mice fed the obesogenic diets showed synovitis, increased intradiscal expression of inflammatory cytokines and circulating levels of MCP-1 compared to control. Linear regression modeling demonstrated that age and diet were both significant predictors of most pain-related behavioral outcomes, but not histopathological joint degeneration. Synovitis was associated with alterations in spontaneous activity.

Conclusion

Diet-induced obesity accelerates IVD degeneration and knee OA in mice; however, pain-related behaviors precede and are independent of histopathological structural damage. These findings contribute to understanding the source of obesity-related back pain and the contribution of structural IVD degeneration.

Advanced glycation end products cause RAGE-dependent annulus fibrosus collagen disruption and loss identified using in situ second harmonic generation imaging in mice intervertebral disk in vivo and in organ culture models

Aging and diabetes are associated with increased low-back pain and intervertebral disk (IVD) degeneration yet causal mechanisms remain uncertain. Advanced glycation end products (AGEs), which accumulate in IVDs from aging and are implicated in diabetes-related disorders, alter collagen and induce proinflammatory conditions. A need exists for methods that assess IVD collagen quality and degradation in order to better characterize specific structural changes in IVDs due to AGE accumulation and to identify roles for the receptor for AGEs (RAGE). We used multiphoton microscopy with second harmonic generation (SHG), collagen-hybridizing peptide (CHP), and image analysis methods to characterize effects of AGEs and RAGE on collagen quality and quantity in IVD annulus fibrosus (AF). First, we used SHG imaging on thin sections with an in vivo dietary mouse model and determined that high-AGE (H-AGE) diets increased AF fibril disruption and collagen degradation resulting in decreased total collagen content, suggesting an early degenerative cascade. Next, we used in situ SHG imaging with an ex vivo IVD organ culture model of AGE challenge on wild type and RAGE-knockout (RAGE-KO) mice and determined that early degenerative changes to collagen quality and degradation were RAGE dependent. We conclude that AGE accumulation leads to RAGE-dependent collagen disruption in the AF and can initiate molecular and tissue level collagen disruption. Furthermore, SHG and CHP analyzes were sensitive to collagenous alterations at multiple hierarchical levels due to AGE and may be useful in identifying additional contributors to collagen damage in IVD degeneration processes.

Risk factors and association of body composition components for lumbar disc herniation in Northwest, Mexico

The goal of this study was to investigate the association of body composition components and to elucidate whether any of these components is a risk factor for Lumbar Disc Herniation (LDH). The group of study consisted of 90 adults involved in a physical activity program due to overweight and obesity. 19 adults with medical diagnostic through Magnetic Resonance Imaging with LDH. Body composition data was obtained with a bioelectrical impedance analyzer. Descriptive statistics and principal components analysis permitted to analyze the information's structure and to visualize information clusters. A logistic regression analysis allowed us to find the association between some of the variables of body composition with LDH. The Degree of Obesity, Body Mass Index, Visceral Fat Area and the Abdominal Circumference resulted associated (P values of 0.0388, 0.0171, 0.0055 and 0.0032, respectively). The application of Odd Ratio allowed us to declare the Visceral Fat Area and Abdominal Circumference as risk factors to develop Lumbar Disk Herniation. Our results provide a new record for future studies, and support for prescription of physical activity and changes in diet, to correct or prevent the development of LDH in the population of Baja California.

Effects of preoperative obesity and psychiatric comorbidities on minimum clinically important differences for lumbar fusion in grade 1 degenerative spondylolisthesis: analysis from the prospective Quality Outcomes Database registry

OBJECTIVE

Medical comorbidities, particularly preoperatively diagnosed anxiety, depression, and obesity, may influence how patients perceive and measure clinical benefit after a surgical intervention. The current study was performed to define and compare the minimum clinically important difference (MCID) thresholds in patients with and without preoperative diagnoses of anxiety or depression and obesity who underwent spinal fusion for grade 1 degenerative spondylolisthesis.

METHODS

The Quality Outcomes Database (QOD) was queried for patients who underwent lumbar fusion for grade 1 degenerative spondylolisthesis during the period from January 2014 to August 2017. Collected patient-reported outcomes (PROs) included the Oswestry Disability Index (ODI), health status (EQ-5D), and numeric rating scale (NRS) scores for back pain (NRS-BP) and leg pain (NRS-LP). Both anchor-based and distribution-based methods for MCID calculation were employed.

RESULTS

Of 462 patients included in the prospective registry who underwent a decompression and fusion procedure, 356 patients (77.1%) had complete baseline and 12-month PRO data and were included in the study. The MCID values for ODI scores did not significantly differ in patients with and those without a preoperative diagnosis of obesity (20.58 and 20.69, respectively). In addition, the MCID values for ODI scores did not differ in patients with and without a preoperative diagnosis of anxiety or depression (24.72 and 22.56, respectively). Similarly, the threshold MCID values for NRS-BP, NRS-LP, and EQ-5D scores were not statistically different between all groups. Based on both anchor-based and distribution-based methods for determination of MCID thresholds, there were no statistically significant differences between all cohorts.

CONCLUSIONS

MCID thresholds were similar for ODI, EQ-5D, NRS-BP, and NRS-LP in patients with and without preoperative diagnoses of anxiety or depression and obesity undergoing spinal fusion for grade 1 degenerative spondylolisthesis. Preoperative clinical and shared decision-making may be improved by understanding that preoperative medical comorbidities may not affect the way patients experience and assess important clinical changes postoperatively.

Work-related Musculoskeletal Symptoms among Agricultural Workers: A Cross-sectional Study in Iran

Objective: In Iran, as in most developing countries, agriculture is considered a hazardous industry. Musculoskeletal disorders (MSD) have been shown to be the most common occupational injury among farmers. The present study was carried out among agricultural workers of Fars province, Iran to determine the prevalence of musculoskeletal symptoms and to assess working postures and ergonomic working conditions to identify the major risk factors associated with MSD. Methods: This cross-sectional study was conducted on 1501 randomly selected Iranian agricultural workers with at least 1 year of job tenure. Data were collected using demographic/occupational questionnaire, Nordic Musculoskeletal Questionnaire (NMQ), Quick Exposure Check (QEC) technique, and ergonomic working conditions checklist. Results: The mean age of the participants was 41.39 ± 13.64 years. The results of NMQ showed the highest prevalence of MSD symptoms was related to lower back (59.3%), knees (36.9%), and upper back (36.6%). Indeed, the QEC score was high or very high (action levels 3 and 4) in 83.1% of the farmers. Moreover, the ergonomic working conditions checklist revealed that the participants' "working postures" index had the lowest mean, indicating poor ergonomic conditions, while "hand tools" had the highest mean, indicating proper ergonomic conditions. Conclusions: The results demonstrated the high prevalence of MSD symptoms among Iranian agricultural workers. Elimination of harmful working postures was recommended to improve working conditions.

Immuohistochemical score of matrix metalloproteinase-1 may indicate the severity of symptomatic cervical and lumbar disc degeneration

BACKGROUND CONTEXT

Intervertebral disc (IVD) degeneration is related to numerous risk factors, including obesity. Leptin, one of the commonly measured adipokines, is proven to play an important role in the pathogenesis of IVD degeneration. In the context of IVD degeneration, matrix metalloproteinase-1 (MMP-1), which is upregulated and activated by leptin, is the most abundant catabolic enzyme. It remains unclear which of the factors mentioned above is most strongly associated with IVD degeneration.

PURPOSE

To investigate the influence of MMP-1 in IVD degeneration, we determined the strength of different predictors, including age, sex, magnetic resonance imaging (MRI), Modic changes (MCs), body mass index (BMI), leptin, and MMP-1. This was achieved by assessing the correlation among these factors and histologic degeneration score (HDS).

STUDY DESIGN

This study included 89 patients undergoing cervical discectomy for disc herniation, 93 who underwent lumbar discectomy, and 90 control subjects. Herniated disc tissue and plasma were used after the study was approved by the Human Ethics Review Committee at the authors' institution.

METHODS

Hematoxylin and eosin (H&E), Alcian blue-PAS and immunohistochemical (IHC) staining were performed to measure the expression levels of leptin and MMP-1. Circulating plasma levels of leptin and MMP-1 were measured using an enzyme-linked immunosorbent assay. To assess the correlation with HDS, measurements of age, sex, BMI, MRI scale, MCs scale, leptin/MMP-1 plasma concentration, and leptin/MMP-1 IHC expression were analyzed.

RESULTS

Patients with cervical or lumbar discectomy had significantly higher BMI than controls. Significantly more men than women were involved in the lumbar patients as compared with the cervical patients and the control subjects. After adjustment for age and sex, plasma leptin and leptin IHC score correlated significantly with BMI in patients with cervical or lumbar discectomy. Age, sex, MRI scale, MCs scale, and leptin/MMP-1 plasma concentration were not positively correlated with HDS. HDS was significantly associated with BMI, leptin IHC score, and MMP-1 IHC score. After a stepwise-multiple linear regression analysis to evaluate the strength of the correlations between HDS and various factors, only the MMP-1 IHC score demonstrated an independent association with HDS in patients with degeneration of the cervical or lumbar disc.

CONCLUSIONS

MMP-1 IHC score is an independent predictor of the severity of cervical or lumbar IVD degeneration.

CLINICAL SIGNIFICANCE

MMP-1 IHC score may be used as an indicator of IVD degeneration.

Leptin and Associated Mediators of Immunometabolic Signaling: Novel Molecular Outcome Measures for Neurostimulation to Treat Chronic Pain

Chronic pain is a devastating condition affecting the physical, psychological, and socioeconomic status of the patient. Inflammation and immunometabolism play roles in the pathophysiology of chronic pain disorders. Electrical neuromodulation approaches have shown a meaningful success in otherwise drug-resistant chronic pain conditions, including failed back surgery, neuropathic pain, and migraine. A literature review (PubMed, MEDLINE/OVID, SCOPUS, and manual searches of the bibliographies of known primary and review articles) was performed using the following search terms: chronic pain disorders, systemic inflammation, immunometabolism, prediction, biomarkers, metabolic disorders, and neuromodulation for chronic pain. Experimental studies indicate a relationship between the development and maintenance of chronic pain conditions and a deteriorated immunometabolic state mediated by circulating cytokines, chemokines, and cellular components. A few uncontrolled in-human studies found increased levels of pro-inflammatory cytokines known to drive metabolic disorders in chronic pain patients undergoing neurostimulation therapies. In this narrative review, we summarize the current knowledge and possible relationships of available neurostimulation therapies for chronic pain with mediators of central and peripheral neuroinflammation and immunometabolism on a molecular level. However, to address the needs for predictive factors and biomarkers, large-scale databank driven clinical trials are needed to determine the clinical value of molecular profiling.

Effect of Obesity on the Development, Management, and Outcomes of Spinal Disorders

Obesity is a major public health issue in the United States, and rates of obesity continue to increase across the population. The association of obesity with degenerative spinal pathology underlies the observation that a substantial number of patients undergoing spine surgery are either overweight or obese. Obesity is a notable independent risk factor for both surgical and medical complications in the perioperative period and an important consideration in preoperative planning, intraoperative strategies, and postoperative management. Despite these increased risks, surgery in obese patients for a variety of degenerative conditions results in improvement in outcomes. Although obese patients may undergo gains that are absolutely lower than their nonobese counterparts, they still experience a positive treatment effect with surgery appropriate for their condition. An evidence-based approach to both preoperative and perioperative management of patients with obesity is not well established. The purpose of this article is to review the effect of obesity on the development, management, and outcomes of patients with spinal disorders and to provide data that may guide an evidence-based approach to care in this expanding patient population.

Elevated glycohemoglobin HbA1c is associated with low back pain in nonoverweight diabetics

BACKGROUND CONTEXT

Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined.

PURPOSE

To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants.

STUDY DESIGN

Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5-25), overweight (BMI 25-30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) ≥6.5%.

PATIENT SAMPLE

11,756 participants from NHANES cohort.

OUTCOME MEASURES

Percentage of LBP reported.

METHODS

LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations.

RESULTS

Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status.

CONCLUSIONS

LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone.

Dietary advanced glycation end-product consumption leads to mechanical stiffening of murine intervertebral discs

Back pain is a leading cause of disability and is strongly associated with intervertebral disc (IVD) degeneration. Reducing structural disruption and catabolism in IVD degeneration remains an important clinical challenge. Pro-oxidant and structure-modifying advanced glycation end-products (AGEs) contribute to obesity and diabetes, which are associated with increased back pain, and accumulate in tissues due to hyperglycemia or ingestion of foods processed at high heat. Collagen-rich IVDs are particularly susceptible to AGE accumulation due to their slow metabolic rates, yet it is unclear whether dietary AGEs can cross the endplates to accumulate in IVDs. A dietary mouse model was used to test the hypothesis that chronic consumption of high AGE diets results in sex-specific IVD structural disruption and functional changes. High AGE diet resulted in AGE accumulation in IVDs and increased IVD compressive stiffness, torque range and failure torque, particularly for females. These biomechanical changes were likely caused by significantly increased AGE crosslinking in the annulus fibrosus, measured by multiphoton imaging. Increased collagen damage measured with collagen hybridizing peptide did not appear to influence biomechanical properties and may be a risk factor as these animals age. The greater influence of high AGE diet on females is an important area of future investigation that may involve AGE receptors known to interact with estrogen. We conclude that high AGE diets can be a source for IVD crosslinking and collagen damage known to be important in IVD degeneration. Dietary modifications and interventions that reduce AGEs warrant further investigation and may be particularly important for diabetics, in whom AGEs accumulate more rapidly.

Summary: Dietary AGEs lead to sex-specific intervertebral disc structural and functional changes and may be targeted for promoting spinal health, especially in diabetes, in which AGEs form rapidly.

Gravidity, Parity, and Vertebral Dimensions in the Northern Finland Birth Cohort 1966

STUDY DESIGN

A population-based birth cohort study.

OBJECTIVE

To investigate the association between gravidity, parity, and vertebral geometry among middle-aged women.

SUMMARY OF BACKGROUND DATA

Vertebral size is a recognized determinant of vertebral fracture risk. Yet, only a few lifestyle factors that influence vertebral size are known. Pregnancy is a labile period that may affect the maternal vertebral size or shape. The lumbar lordosis angle is permanently deepened by pregnancy, but it remains unclear whether vertebral shape or size contribute to this deepened angle.

METHODS

We aimed to investigate whether gravidity and parity were associated with vertebral cross-sectional area (CSA) and height ratio (anterior height to posterior height) among 705 middle-aged women from the Northern Finland Birth Cohort 1966. We measured the corpus of their fourth lumbar vertebra using magnetic resonance imaging of the lumbar spine at the age of 46. Gravidity and parity were elicited using a questionnaire also at the age of 46. Linear regression analysis was used with adjustments for body mass index, vertebral CSA (height ratio models), and vertebral height (CSA models). We also ran a subgroup analysis that did not include nulliparous women, and we compared nulliparous women with grand multiparous women.

RESULTS

The models found no statistically significant associations between the predictors and outcomes. Crude and adjusted results were highly similar, and the subgroup analyses provided analogous results.

CONCLUSION

Pregnancy, or even multiple pregnancies, do not seem to have long-term effects on vertebral geometry. In order to enhance the prevention of vertebral fractures, future studies should aim to reveal more lifestyle determinants of vertebral size.

LEVEL OF EVIDENCE

3.

Asymmetry between the superior and inferior endplates is a risk factor for lumbar disc degeneration

Endplate pathology plays an important role in the development of lumbar disc degeneration. Previous research paid little attention to differences between the superior and inferior endplates as a possible risk factor for disc degeneration. The purpose of this study was to test the hypothesis that asymmetry between the superior and inferior endplates is a risk factor for the development of lumbar disc degeneration. A total of 134 patients with lumbar disc herniation (LDH) and 100 healthy adults ("Controls") underwent magnetic resonance imaging scans. Each disc was categorized as non-degenerated (Pfirrmann grades I-II) or degenerated (Pfirrmann grades III-V) and get the following three groups: "Degenerated LDH" discs (n = 145), "Non-degenerated LDH" discs (n = 525) and "Non-degenerated Control" discs (n = 500). On mid-sagittal image, the lumbar endplate morphology could be categorized into three types: Flat, concave, and irregular. Superior and inferior endplates of a given disc were "symmetric" if both were of the same type, and "asymmetric" if they were of different types. The proportion of asymmetric endplates at L4-5 was higher in the "Degenerated LDH" discs group (47%) than in the "Non-degenerated LDH" discs group (21%) or "Non-degenerated Control" discs group (7%) (p < 0.05). At L5-S1 the proportions were 73%, 55%, and 38% (p < 0.05). Asymmetry of superior and inferior endplates in the mid-sagittal plane is a risk factor for lumbar disc degeneration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2469-2475, 2018.

Bariatric surgery before elective posterior lumbar fusion is associated with reduced medical complications and infection

BACKGROUND CONTEXT

Severely obese patients with operative spinal pathology present a challenge to the spine surgeon, given the increased complication risk.

PURPOSE

We aimed to determine the impact of bariatric surgery (BS) on perioperative complications of posterior lumbar fusion.

STUDY DESIGN

This is a retrospective cohort study.

PATIENT SAMPLE

Patients undergoing posterior lumbar fusion surgery in the State Inpatient Databases of New York, Florida, North Carolina, Nebraska, Utah, and California comprised the patient sample.

OUTCOMES

Thirty-day medical complications, surgical complications (nerve injury, infection, revision), death, readmission, and hospital length of stay (LOS) were the study's outcomes.

METHODS

We analyzed 156,517 patients using International Classification of Diseases, Ninth Revision codes. Patients were categorized into three groups: Group 1: history of BS and obesity, Group 2: severe obesity, body mass index (BMI)>40 (severely obese), and Group 3: normal weight, BMI<25 (non-obese). Logistic and linear multivariate regressions were performed to compare complications and LOS, respectively, between BS and severely obese groups and BS and non-obese groups while controlling for confounders. There were no sources of funding for this study.

RESULTS

There were 590 patients with BS, 5,791 severely obese, and 150,136 non-obese. Comparing BS with severely obese, BS had significantly lower rates of respiratory failure (odds ratio [OR] 0.59, p=.019), urinary tract infection (OR 0.64, p=.031), acute renal failure (OR 0.39, p=.007), overall medical complications (OR 0.59, p<.001), and infection (OR 0.65, p=.025). Bariatric surgery also had significantly lower hospital LOS (B=-0.46, p=.01). Comparing BS with non-obese, there were no significant differences in medical complications; however, BS had significantly higher rates of infection (OR 2.70, p<.001), reoperation (OR 2.05, p=.045), and readmission (OR 1.89, p<.001).

CONCLUSION

Bariatric surgery before elective posterior lumbar fusion mitigates risk of medical complications and infection. However, these patients still have increased risk of infection, revision surgery, and readmission compared with patients with normal BMI. Surgeons might consider referral for BS for the severely obese patient before undergoing spine surgery.

Chondrocyte death after mechanically overloading degenerated human intervertebral disk explants is associated with a structurally impaired pericellular matrix

A type VI collagen-rich pericellular matrix (PCM) encloses both intervertebral disk (IVD) and articular cartilage chondrocytes. In the latter, the PCM protects the chondrocytes from mechanical overload, whereas tissue degeneration is associated with PCM destruction. As little is known about the IVD PCM, we investigated chondrocyte survival after mechanical overload as well as PCM structural integrity as a function of clinical tissue degeneration. The hypothesis was that IVD degeneration may affect PCM integrity and overload-related chondrocyte survival. Cylindrical human IVD explants from patients undergoing surgical procedures for lumbar disk degeneration, disk prolapse, or spinal trauma were generated and scored. Mechanical overload was applied by single uniaxial 50% compression followed by immediate release, and the explants were live-dead stained (n = 20 explants). Type VI collagen, the major PCM component, was fluorescent stained and the extent was determined, in which individual cells were enclosed by a recognizable PCM; this was termed PCM fraction. More than 50% of chondrocytes in all degenerative IVD explants displayed <25% PCM fraction and a lower PCM fraction correlated with higher cell numbers (p < 0.001), suggesting a PCM structural impairment in IVD degeneration that is associated with chondrocyte clustering. Mechanical overload-induced significantly increased cell death (p = 0.005), and the PCM fraction was significantly lower in overload-induced cell death than in live cells (p = 0.042), suggesting that a fully present PCM has a protective role in mechanical overload. Collectively, human IVD degeneration is associated with a structural impairment of the PCM, which may promote cell death under mechanical overload.

Trans-Ethnic Polygenic Analysis Supports Genetic Overlaps of Lumbar Disc Degeneration With Height, Body Mass Index, and Bone Mineral Density

Lumbar disc degeneration (LDD) is age-related break-down in the fibrocartilaginous joints between lumbar vertebrae. It is a major cause of low back pain and is conventionally assessed by magnetic resonance imaging (MRI). Like most other complex traits, LDD is likely polygenic and influenced by both genetic and environmental factors. However, genome-wide association studies (GWASs) of LDD have uncovered few susceptibility loci due to the limited sample size. Previous epidemiology studies of LDD also reported multiple heritable risk factors, including height, body mass index (BMI), bone mineral density (BMD), lipid levels, etc. Genetics can help elucidate causality between traits and suggest loci with pleiotropic effects. One such approach is polygenic score (PGS) which summarizes the effect of multiple variants by the summation of alleles weighted by estimated effects from GWAS. To investigate genetic overlaps of LDD and related heritable risk factors, we calculated the PGS of height, BMI, BMD and lipid levels in a Chinese population-based cohort with spine MRI examination and a Japanese case-control cohort of lumbar disc herniation (LDH) requiring surgery. Because most large-scale GWASs were done in European populations, PGS of corresponding traits were created using weights from European GWASs. We calibrated their prediction performance in independent Chinese samples, then tested associations with MRI-derived LDD scores and LDH affection status. The PGS of height, BMI, BMD and lipid levels were strongly associated with respective phenotypes in Chinese, but phenotype variances explained were lower than in Europeans which would reduce the power to detect genetic overlaps. Despite of this, the PGS of BMI and lumbar spine BMD were significantly associated with LDD scores; and the PGS of height was associated with the increased the liability of LDH. Furthermore, linkage disequilibrium score regression suggested that, osteoarthritis, another degenerative disorder that shares common features with LDD, also showed genetic correlations with height, BMI and BMD. The findings suggest a common key contribution of biomechanical stress to the pathogenesis of LDD and will direct the future search for pleiotropic genes.

A Positive Feedback Loop Between Th17 Cells and Dendritic Cells in Patients with Endplate Inflammation

BACKGROUND

Endplate inflammation remains a difficult disease to treat, in part due to its unclear pathology. Previous experiments showed that patients with idiopathic inflammation presented a systemic upregulation of Th17 cells. Here, we investigated how this change might affect the inflammatory environment in endplate inflammation.

METHODS

Peripheral blood was obtained from patients and healthy controls, and Th17 cells were examined.

RESULTS

Th17 cells significantly increased the differentiation of CD11c+ and DC-SIGN+ dendritic cells (DCs) from circulating monocytes in the absence of exogenous stimulation as well as in the presence of LPS stimulation. Th17 cells also increased CD80 and CD86 expression by DCs. Importantly, although Th17 cells from both healthy controls and patients with endplate inflammation could induce CD11c, DC-SIGN, CD80, and CD86 expression, Th17 cells from patients with endplate inflammation showed significantly more potent capacity. Both contact-dependent and IL-17-dependent mechanisms were employed by Th17 cells, since blocking cell-to-cell contact significantly inhibited Th17-mediated differentiation of CD11c+ DCs, and neutralization of IL-17 reduced the expression of CD80 and CD86. Strikingly, DCs following incubation with Th17 cells, but not the DCs derived directly from monocytes without Th17 cells, could significantly promote the expression of IL-17 from naive CD4+ T cells.

CONCLUSIONS

These results demonstrated that Th17 cells from patients with endplate inflammation could potently induce the differentiation and activation of DCs that preferentially promoted IL-17 response in a positive feedback loop.

Nanofibrous scaffolds for biomedical applications

Tissue engineering is an emergent and very interesting research field, providing potential solutions for a myriad of challenges in healthcare. Fibrous scaffolds specifically have shown promise as an effective tissue engineering method, as their high length-to-width ratio mimics that of extracellular matrix components, which in turn guides tissue formation, promotes cellular adhesion and improves mechanical properties. In this review paper, we discuss in detail both the importance of fibrous scaffolds for the promotion of tissue growth and the different methods to produce fibrous biomaterials to possess favorable and unique characteristics. Here, we focus on the pressing need to develop biomimetic structures that promote an ideal environment to encourage tissue formation. In addition, we discuss different biomedical applications in which fibrous scaffolds can be useful, identifying their importance, relevant aspects, and remaining significant challenges. In conclusion, we provide comments on the future direction of fibrous scaffolds and the best way to produce them, proposed in light of recent technological advances and the newest and most promising fabrication techniques.

A method for characterising human intervertebral disc glycosaminoglycan disaccharides using liquid chromatography-mass spectrometry with multiple reaction monitoring

Intervertebral disc (IVD) degeneration results in the depletion of proteoglycans and glycosaminoglycans (GAGs), which can lead to structural and mechanical loss of IVD function, ingrowth of nociceptive nerve fibres and eventually discogenic pain. Specific GAG types as well as their disaccharide patterns can be predictive of disease and degeneration in several tissues but have not been comprehensively studied within the IVD. A highly sensitive mass spectrometry based technique with multiple reaction monitoring (MRM) was used to provide characterisation of chondroitin sulphate (CS), hyaluronic acid (HA), heparan sulphate (HS) and their disaccharide sulphation patterns across different anatomical regions of human IVDs. Principal component analysis further distinguished important regional variations and proposed potential ageing variations in GAG profiles. CS was the GAG in greatest abundance in the IVD followed by HA and HS. Principal component analysis identified clear separation of GAG profiles between nucleus pulposus and annulus fibrosus in young and old specimens. Distinct patterns of predominantly expressed disaccharides of CS and HS between young and old IVD samples, provided preliminary evidence that important alterations in disaccharides occur within IVDs during ageing. This technique offered a novel approach to identify and quantify specific GAG disaccharides in human IVDs and the data presented were the first to offer insight into the spatial distribution as well as association with ageing of GAGs and GAG disaccharide sulphation patterns across the human IVD.

Adipsin Concentrations Are Associated with Back Pain Independently of Adiposity in Overweight or Obese Adults

Objective: To compare cardiometabolic risk factors including cytokine and adipokine concentrations between individuals with and without back pain. Methods: In 62 overweight/obese adults (BMI ≥ 25 kg/m2; 23F/39M), we collected data on: self-reported back pain; anthropometry [BMI, waist circumference, body composition (dual energy X-ray absorptiometry-DEXA)]; metabolic parameters [fasting glucose; insulin sensitivity (hyperinsulinaemic-euglycaemic clamps)]; cardiovascular parameters (blood pressure, lipids); serum inflammation markers [high-sensitivity C-reactive protein (hsCRP; immunoturbidimetric-assay), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-10 (multiplex-assay)]; and adipokines [leptin, adipsin, resistin, and adiponectin (multiplex-assay)]. Results: Participants who reported having back pain in the past month (n = 24; 39%) had higher BMI (mean ± SD = 33.8 ± 6.3 vs. 30.2 ± 4.1 kg/m2, p = 0.008), fat-mass (39.9 ± 12.3 vs. 33.9 ± 9.8%, p = 0.04), and waist circumference (109.6 ± 16.8 vs. 101.0 ± 9.3 cm, p = 0.01) compared to those without back pain (n = 38; 61%). No differences were observed in cardiometabolic parameters, inflammatory markers, or adiponectin or resistin concentrations. Those reporting back pain had higher adipsin concentrations compared to those without back pain [median (IQR) = 744 (472-2,804) vs. 721 (515-867) ng/ml, p = 0.03], with a trend for higher leptin [5.5 (1.5-24.3) vs. 2.3 (1.5-6.7) ng/ml, p = 0.05], both of which persisted after adjustment for age and sex. Adipsin remained associated with back pain independently of adiposity (BMI, waist, fat-mass, or total %body fat; all p ≤ 0.03). Conclusions: Greater obesity, and higher adipsin and leptin concentrations were observed in those who reported back pain in the past month compared to those without back pain, and adipsin was associated with back pain independently of adiposity. Larger studies are needed to determine if adipsin could be a novel therapeutic target for prevention and/or treatment of back pain.

Changes of Metabolic Disorders Associated Peripheral Cytokine/Adipokine Traffic in Non-Obese Chronic Back Patients Responsive to Burst Spinal Cord Stimulation

OBJECTIVES

In our previous study, anti-inflammatory IL-10 serum levels were significantly elevated after burst spinal cord stimulation (SCS) in back pain patients and correlated with pain intensity. This current study extended cytokine analysis including metabolic-associated adipokine/cytokine serum assessment in chronic back pain patients with co-existing metabolic disorders such as diabetes, hypertension, and cardiovascular diseases.

METHODS

At baseline and after three months of burst SCS treatment, leptin (LP), adiponectin (AN), and ghrelin (GH) were recorded in non-/pre-obese chronic back pain patients with co-existing metabolic disorders and compared to age-/gender-matched healthy controls (HC).

RESULTS

Mean BMI was 22 ± 0.81 kg/m² in 12 (five male/seven female) participants with diabetes in 6/12 (50%), hypertension in 9 (75%), and CVD in five patients (42%). Pre- and post-SCS LP levels were significantly higher compared to healthy controls: pre-SCS, 30567 (12,996-58,821) vs. HC, 7952 (4932-12,583) pg/mL, p = 0.029; post-SCS, 18,890 (7140-44,719) vs. HC, 7952 (4932-12,583) pg/mL, p = 0.035. Pre- and post-SCS changes of GH (p = 0.18) and AN (p = 0.8) did not differ significantly. GH serum levels correlated with AN (Spearman r = 0.5; p = 0.012; 95 CI 0.11 to -0.76) and AN levels were significantly correlated with higher age (Pearson correlation r = 0.8; p = 0.002; 95 CI 0.41-0.94) at baseline.

CONCLUSIONS

This study determined serum changes of metabolic-associated cytokines/adipokines in non-obese chronic back pain patients responsive to burst SCS suggesting that neuroinflammation assessment may consider pain-associated mood, cognition, sleep, and metabolic state.

High-fat diet increases pain behaviors in rats with or without obesity

Obesity is associated with increased risk for chronic pain. Basic mechanisms for this association are poorly understood. Using a milder version of a radicular pain model, local inflammation of the dorsal root ganglion (DRG), we observed marked increases in mechanical and cold allodynia in rats of both sexes that were maintained on a high-fat diet (HFD) for 6 weeks prior to DRG inflammation. Notably, this increase in pain-related behaviors occurred in both Long-Evans and Sprague-Dawley rats despite the fact that the 6-week HFD exposure induced obesity (e.g., increased insulin, leptin, weight, and percent body fat) in the Long-Evans, but not Sprague-Dawley, strains. This suggested that HFD, rather than obesity per se, increased pain behaviors. Increased pain behaviors were observed even after a much shorter (1 week) exposure to the HFD but the effect was smaller. HFD also increased behavioral responses and paw swelling to paw injection of complete Freund’s adjuvant, a model of peripheral inflammatory pain. No change was detected in plasma cytokine levels in HFD rats. However, increased macrophage infiltration of the DRG was observed in response to the HFD, absent any pain model. The results suggest that HFD can increase pain even when it does not cause obesity.

[Impact of obesity in the pathophysiology of degenerative disk disease and in the morbidity and outcome of lumbar spine surgery]

Obesity (BMI>30Kg/m²) is a pandemic with severe medical and financial implications. There is growing evidence that relates certain metabolic processes within the adipose tissue, preferentially abdominal fat, with a low-intensity chronic inflammatory state mediated by adipokines and other substances that favor disk disease and chronic low back pain. Obesity greatly conditions both the preoperative evaluation and the spinal surgical technique itself. Some meta-analyses have confirmed an increase of complications following lumbar spine surgery (mainly infections and venous thrombosis) in obese subjects. However, functional outcomes after lumbar spine surgery are favorable although inferior to the non-obese population, acknowledging that obese patients present with worse baseline function levels and the prognosis of conservatively treated obese cohorts is much worse. The impact of preoperative weight loss in spine surgery has not been prospectively studied in these patients.

Low back pain in older adults: risk factors, management options and future directions

Low back pain (LBP) is one of the major disabling health conditions among older adults aged 60 years or older. While most causes of LBP among older adults are non-specific and self-limiting, seniors are prone to develop certain LBP pathologies and/or chronic LBP given their age-related physical and psychosocial changes. Unfortunately, no review has previously summarized/discussed various factors that may affect the effective LBP management among older adults. Accordingly, the objectives of the current narrative review were to comprehensively summarize common causes and risk factors (modifiable and non-modifiable) of developing severe/chronic LBP in older adults, to highlight specific issues in assessing and treating seniors with LBP, and to discuss future research directions. Existing evidence suggests that prevalence rates of severe and chronic LBP increase with older age. As compared to working-age adults, older adults are more likely to develop certain LBP pathologies (e.g., osteoporotic vertebral fractures, tumors, spinal infection, and lumbar spinal stenosis). Importantly, various age-related physical, psychological, and mental changes (e.g., spinal degeneration, comorbidities, physical inactivity, age-related changes in central pain processing, and dementia), as well as multiple risk factors (e.g., genetic, gender, and ethnicity), may affect the prognosis and management of LBP in older adults. Collectively, by understanding the impacts of various factors on the assessment and treatment of older adults with LBP, both clinicians and researchers can work toward the direction of more cost-effective and personalized LBP management for older people.

The Effects of Obesity on Spine Surgery: A Systematic Review of the Literature

Study Design Literature review. Objective The aim of this literature review is to examine the effects of obesity on postoperative complications and functional outcomes after spine surgery. Methods A review of the relevant literature examining the effects of obesity and spine surgery was conducted using PubMed, Google Scholar, and Cochrane databases. Results Obesity contributes to disk degeneration and low back pain and potentially increases the risk of developing operative pathology. Obese patients undergoing spine surgery have a higher risk of developing postoperative complications, particularly surgical site infection and venous thromboembolism. Though functional outcomes in this population may not mirror the general population, the treatment effect associated with surgery is at least equivalent if not better in obese individuals. This reduction is primarily due to worse outcomes associated with nonoperative treatment in the obese population. Conclusion Obese individuals represent a unique patient population with respect to nonoperative treatment, postoperative complication rates, and functional outcomes. However, given the equivalent or greater treatment effect of surgery, this comorbidity should not prohibit obese patients from undergoing operative intervention. Future investigations in this area should attempt to develop strategies to minimize complications and improve outcomes in obese individuals and also examine the role of controlled weight loss preoperatively to mitigate these risks.

RASSF7 expression and its regulatory roles on apoptosis in human intervertebral disc degeneration

Apoptosis plays an important role in intervertebral disc degeneration (IDD). Overwhelming evidence indicates that RASSF7 is essential for cell growth and apoptosis. Recently, it has been noted that the JNK signaling can be negatively regulated by suppressing phosphorylated-MKK7 activation during pro-apoptosis. We aimed to investigate the RASSF7 expression level in human degenerative nucleus pulposus (NP) cells and non-degenerative NP cells and the link between RASSF7-JNK with NP cells apoptosis. We harvested NP tissues from 20 IDD patients as disease group and 8 cadaveric donors as normal controls. We detected RASSF7 expression by Real-time-PCR and western blotting. Consequently, we found that the expression of RASSF7 was higher in non-degenerative group than in degenerative group (P<0.05). Overexpression of RASSF7 in degenerative NP cells led to decreased apoptosis rate than that in scramble group (P<0.05). Collectively, our findings suggest that RASSF7 plays an important role in human IDD and RASSF7 might be potentially developed as a curative agent.

Impact of obesity on complications, infection, and patient-reported outcomes in adult spinal deformity surgery

OBJECT

Adult spinal deformity (ASD) surgery is known for its high complication rate. This study examined the impact of obesity on complication rates, infection, and patient-reported outcomes in patients undergoing surgery for ASD.

METHODS

This study was a retrospective review of a multicenter prospective database of patients with ASD who were treated surgically. Patients with available 2-year follow-up data were included. Obesity was defined as having a body mass index (BMI) ≥ 30 kg/m2. Data collected included complications (total, minor, major, implant-related, radiographic, infection, revision surgery, and neurological injury), estimated blood loss (EBL), operating room (OR) time, length of stay (LOS), and patient-reported questionnaires (Oswestry Disability Index [ODI], Short Form-36 [SF-36], and Scoliosis Research Society [SRS]) at baseline and at 6 weeks, 1 year, and 2 years postoperatively. The impact of obesity was studied using multivariate modeling, accounting for confounders.

RESULTS

Of 241 patients who satisfied inclusion criteria, 175 patients were nonobese and 66 were obese. Regression models showed that obese patients had a higher overall incidence of major complications (IRR 1.54, p = 0.02) and wound infections (odds ratio 4.88, p = 0.02). Obesity did not increase the number of minor complications (p = 0.62), radiographic complications (p = 0.62), neurological complications (p = 0.861), or need for revision surgery (p = 0.846). Obesity was not significantly correlated with OR time (p = 0.23), LOS (p = 0.9), or EBL (p = 0.98). Both groups experienced significant improvement overtime, as measured on the ODI (p = 0.0001), SF-36 (p = 0.0001), and SRS (p = 0.0001) questionnaires. However, the overall magnitude of improvement was less for obese patients (ODI, p = 0.0035; SF-36, p = 0.0012; SRS, p = 0.022). Obese patients also had a lower rate of improvement over time (SRS, p = 0.0085; ODI, p = 0.0001; SF-36, p = 0.0001).

CONCLUSIONS

This study revealed that obese patients have an increased risk of complications following ASD correction. Despite these increased complications, obese patients do benefit from surgical intervention; however, their improvement in health-related quality of life (HRQL) is less than that of nonobese patients.

Association of Fat Mass and Adipokines With Foot Pain in a Community Cohort

OBJECTIVE

To determine, first, if fat mass index (FMI) or fat-free mass index (FFMI) and serum adipokines tumor necrosis factor (TNF) and interleukin-6 (IL-6) are associated with prevalent (stage 2) foot pain, and, second, if they are predictive of future (stage 3) foot pain.

METHODS

A subset of participants ages ≥50 years (n = 1,462) from the North West Adelaide Health Study were used for this study. Participants from this community cohort were asked in stage 2 (2004-2006) and stage 3 (2008-2010) if they had foot pain, aching, or stiffness. In stage 2, serum adipokines and anthropometry were measured, while body composition was analyzed with dual x-ray absorptiometry. These variables, along with comorbidities and social history, were used in logistic regression analyses to determine if FMI, FFMI, and serum adipokines were associated with foot pain.

RESULTS

Prevalent foot pain was present in 20.2% of participants, and future foot pain in 36.4%. Following multivariate modeling, the odds of having pain at stage 2 increased by 8% for each FMI unit (odds ratio [OR] 1.08, 95% confidence interval [95% CI] 1.04-1.12), while the odds of having pain at stage 3 increased by 6% for each FMI unit at stage 2 (OR 1.06, 95% CI 1.02-1.11). TNF level, IL-6 level, and FFMI were not associated with pain.

CONCLUSION

Increased FMI, but not body mass index, FFMI, or TNF or IL-6 level, was associated with both prevalent and future foot pain. These results suggest that body fat may be more important than body weight with respect to foot pain. The role played by other adipokines requires further investigation.