Outcome of lumbar epidural steroid injection is predicted by assay of a complex of fibronectin and aggrecan from epidural lavage

Effectiveness of Epidural Steroid Injection Depending on Discoradicular Contact: A Prospective Randomized Trial

Lumbar radicular pain is a major public health and economic problem. It is among the most common reasons for professional disability. The most common cause of lumbar radicular pain is intervertebral disc herniation, which results from degenerative disc changes. The dominant pain mechanisms are direct pressure of the hernia on the nerve root and the local inflammatory process triggered by intervertebral disc herniation. Treatment of lumbar radicular pain includes conservative, minimally invasive, and surgical treatment. The number of minimally invasive procedures is constantly increasing, and among these methods is epidural administration of steroids and local anesthetic through a transforaminal approach (ESI TF). The aim of this research was to examine the effectiveness of ESI TF as measured by a visual analog scale (VAS) and the Oswestry Disability Index (ODI), depending on whether there is contact between the herniated intervertebral disc and the nerve root. In both groups of participants, there was a significant reduction in pain intensity, but there was no significant difference between the groups. In the group with disc herniation and nerve root contact, the only significant reduction was in pain intensity (p < 0.001). There were no significant differences in measurements in other domains of the ODI. In the group without disc herniation and nerve contact, there was a significant difference in all domains except weight lifting. In the group without contact, there was significant improvement after 1 month (p = 0.001) and 3 months (p < 0.001) according to the ODI, while there was no significant improvement in the group with contact. In addition, there were no significant differences in the distribution of participants based on the ODI and whether disc herniation and nerve contact was present. The results suggest that transforaminal epidural administration of steroids is a clinically effective method for treating lumbar radicular pain caused by intervertebral disc herniation in people with and without nerve root contact, without significant differences.

Association of Protein and Genetic Biomarkers With Response to Lumbar Epidural Steroid Injections in Subjects With Axial Low Back Pain

OBJECTIVE

The purpose of this observational study was to examine the association of protein and genetic biomarkers with pain and pain-related disability in individuals with axial low back pain undergoing epidural steroid injections.

DESIGN

Forty-eight adults with axial low back pain undergoing an epidural steroid injection were recruited from an academic medical center. Blood samples were assayed at baseline and follow-up for plasma proteins and functional single-nucleotide polymorphisms associated with pain. Data regarding pain and function were collected at baseline and follow-up. The characteristics of responders (defined as 50% improvement in pain score) and nonresponders were compared, and the association between response and baseline biomarkers was examined.

RESULTS

Thirty-five percent of subjects were responders to injection. Responders had lower baseline plasma levels of chondroitin sulfate 846 and higher neuropeptide Y and serotonin levels than nonresponders, and baseline neuropeptide Y level correlated with change in disability levels. In addition, subjects with the variant allele for the catechol-O-methyltransferase single-nucleotide polymorphism demonstrated increased odds of responding to the injection.

CONCLUSIONS

These data identify candidates who may have utility for patient selection for spinal procedures and provide support for exploration in prospective studies to assess and validate their predictive ability.

Predicting Response to Epidural Steroid Injections for Lumbar Spinal Stenosis with Biomarkers and Electromyography

BACKGROUND

Epidural steroid injections (ESIs) may be beneficial for lumbar spinal stenosis (LSS) symptoms. Past studies found interferon-gamma, fibronectin-aggrecan complex, and electromyography (EMG) to predict patients' response to ESIs for other spinal pathologies, but no similar studies have been done for LSS.

OBJECTIVE

To explore the ability of biomarkers and EMG to help predict outcome after ESI in LSS.

DESIGN

Prospective observational cohort.

SETTING

The physical medicine & rehabilitation spine clinic at a tertiary care center.

PARTICIPANTS

Eleven patients with LSS were recruited from the spine clinic at a Veterans Affairs Medical Center.

INTERVENTIONS

Participants underwent one interlaminar ESI. Before ESI, the following data were collected: pain intensity on visual analog scale (VAS), disability via the Pain Disability Questionnaire (PDQ) and LSS symptoms via the Swiss Spinal Stenosis Questionnaire (SSSQ), serum high-sensitivity C-reactive protein level, standard diagnostic EMG, assay of epidural lavasate (epidural saline lavage performed immediately prior to ESI) and serum cytokine biomarkers indicative of inflammation.

OUTCOME MEASURES

Leg pain intensity (VAS), disability (PDQ), LSS symptoms (SSSQ) and satisfaction (SSSQ satisfaction subscale) were assessed at 1 and 2 months following ESI. Pearson correlational coefficients were calculated between independent variables and outcome measures.

RESULTS

Serum monocyte chemoattractant protein-1 (MCP-1) level positively correlated with improvement on 2-month satisfaction. Abnormal EMG finding of radiculopathy positively correlated with improvement in PDQ score at 1 month. Epidural cytokine levels were not detectable in most samples, except for scattered marginally elevated levels in a few cytokines such as MCP-1, RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted) and interleukin-1b.

CONCLUSIONS

This exploratory pilot study revealed that some biomarkers and EMG findings indicative of inflammation and nerve root injury may be predictive of improvement following ESI in patients with LSS. The results of this study will be used to inform a fully powered study to further evaluate these relationships in LSS patients.

Does the presence of the fibronectin-aggrecan complex predict outcomes from lumbar discectomy for disc herniation?

BACKGROUND CONTEXT

Protein biomarkers associated with lumbar disc disease have been studied as diagnostic indicators and therapeutic targets. Recently, a cartilage degradation product, the fibronectin-aggrecan complex (FAC) identified in the epidural space, has been shown to predict response to lumbar epidural steroid injection in patients with radiculopathy from herniated nucleus pulposus (HNP).

PURPOSE

Determine the ability of FAC to predict response to microdiscectomy for patients with radiculopathy due to lumbar disc herniation STUDY DESIGN/SETTING: Single-center prospective consecutive cohort study.

PATIENT SAMPLE

Patients with radiculopathy from HNP with concordant symptoms to MRI who underwent microdiscectomy.

OUTCOMES MEASURES

Oswestry disability index (ODI) and visual analog scores (VAS) were noted at baseline and at 3-month follow-up. Primary outcome of clinical improvement was defined as patients with both a decrease in VAS of at least 3 points and ODI >20 points.

METHODS

Intraoperative sampling was done via lavage of the excised fragment by ELISA for presence of FAC. Funding for the ELISA was provided by Cytonics, Inc.

RESULTS

Seventy-five patients had full complement of data and were included in this analysis. At 3-month follow-up, 57 (76%) patents were "better." There was a statistically significant association of the presence of FAC and clinical improvement (p=.017) with an 85% positive predictive value. Receiver-operating-characteristic (ROC) curve plotting association of FAC and clinical improvement demonstrates an area under the curve (AUC) of 0.66±0.08 (p=.037). Subset analysis of those with weakness on physical examination (n=48) plotting the association of FAC and improvement shows AUC on ROC of 0.81±0.067 (p=.002).

CONCLUSIONS

Patients who are "FAC+" are more likely to demonstrate clinical improvement following microdiscectomy. The data suggest that the inflammatory milieu plays a significant role regarding improvement in patients undergoing discectomy for radiculopathy in lumbar HNP, even in those with preoperative weakness. The FAC represents a potential target for treatment in HNP.

The effect of transforaminal epidural steroid injections in patients with spondylolisthesis

BACKGROUND

Transforaminal epidural steroid injection (TFE) is a widely accepted non-surgical treatment for pain in patients with spondylolisthesis. However, the effectiveness of TFE has not been compared in patients with degenerative (DS) and isthmic spondylolisthesis (IS).

OBJECTIVE

To compare the effectiveness of bilateral TFEs in DS and IS.

METHODS

Patients who underwent bilateral TFEs for spondylolisthesis at University of California San Francisco Orthopaedic Institute from 2009 to 2014 were evaluated retrospectively.

RESULTS

DS patients (120 female, 51 male) were significantly older and had higher comorbidity than those with IS (18 female, 14 male). They had better pain relief after TFE than patients with IS (72.11 ± 27.46% vs 54.39 ± 34.31%; p = 0.009). The number of TFEs, the mean duration of pain relief after TFE, follow-up periods, translation and facet joint widening were similar in DS and IS groups (p > 0.05). DS group had higher successful treatment rate (66.1% vs 46.9%, p = 0.009) and longer duration of pain relief (181.29 ± 241.37 vs 140.07 ± 183.62 days, p = 0.065) compared to IS group.

CONCLUSIONS

Bilateral TFEs at the level of spondylolisthesis effectively decreased pain in patients. TFEs provided better pain relief for longer duration in patients with DS than for those with IS.

Treatment of lumbar degenerative disc disease-associated radicular pain with culture-expanded autologous mesenchymal stem cells: a pilot study on safety and efficacy

Background

Degenerative disc disease (DDD) is a common cause of lower back pain with radicular symptoms and has a significant socioeconomic impact given the associated disability. Limited effective conservative therapeutic options result in many turning to surgical alternatives for management, which vary in the rate of success and also carry an increased risk of morbidity and mortality associated with the procedures. Several animal based studies and a few human pilot studies have demonstrated safety and suggest efficacy in the treatment of DDD with mesenchymal stem cells (MSCs). The use of bone marrow-derived MSCs for the treatment of DDD is promising and in the present study we report on the safety and efficacy findings from a registry based proof of concept study using a percutaneous intradiscal injection of cultured MSCs for the management of DDD with associated radicular symptoms.

Methods

Thirty-three patients with lower back pain and disc degeneration with a posterior disc bulge diagnosed on magnetic resonance imaging (MRI) met the inclusion criteria and were treated with culture-expanded, autologous, bone marrow-derived MSCs. Prospective registry data was obtained at multiple time intervals up to 6 years post-treatment. Collected outcomes included numeric pain score (NPS), a modified single assessment numeric evaluation (SANE) rating, functional rating index (FRI), measurement of the intervertebral disc posterior dimension, and adverse events.

Results

Three patients reported pain related to procedure that resolved. There were no serious adverse events (i.e. death, infection, or tumor) associated with the procedure. NPS change scores relative to baseline were significant at 3, 36, 48, 60, and 72 months post-treatment. The average modified SANE ratings showed a mean improvement of 60% at 3 years post-treatment. FRI post-treatment change score averages exceeded the minimal clinically important difference at all time points except 12 months. Twenty of the patients treated underwent post-treatment MRI and 85% had a reduction in disc bulge size, with an average reduction size of 23% post-treatment.

Conclusions

Patients treated with autologous cultured MSCs for lower back pain with radicular symptoms in the setting of DDD reported minor adverse events and significant improvements in pain, function, and overall subjective improvement through 6 years of follow-up.

NCT03011398. A Clinical Registry of Orthobiologics Procedures. https://clinicaltrials.gov/ct2/show/NCT03011398?term=orthobiologics&rank=1

Three week results of transforaminal epidural steroid injection in patients with chronic unilateral low back related leg pain: The relation to MRI findings and clinical features

BACKGROUND

Transforaminal epidural steroid injection (TESI) is a frequently used intervention for lumbar radicular pain.

OBJECTIVE

To evaluate the value of MRI findings, neurologic assessment and the Slump test (neurodynamic test) as predictors of treatment response to TESI.

METHOD

One hundred subjects (mean age 58 [SD13], 54% females) were included in this trial. The sample was stratified by location of disc herniaton, grade of nerve root compression, clinically assessed neurologic deficit and positive Slump test.Treatment response was primarily evaluated by Visual Analogue Scale for leg pain after three weeks. Predictive value for each stratum was analyzed using logistic regression after the sample was dichotomized into definite treatment response (≥ 50% reduction of pain) and negative response (≤ 0% reduction) to TESI (the 1-49% reduction group was excluded).

RESULTS

The overall definite treatment response rate was 27%. The Slump test was the only predictor of the response to TESI (p= 0.031). The definite treatment response rates for subjects with positive and negative Slump test were 33% and 15%, respectively.

CONCLUSION

In patients with chronic low back related leg pain, MRI findings and neurologic assessment results failed to predict treatment response, whereas a positive Slump test predicted the best 3-week response to TESI.

SF-36 total score as a single measure of health-related quality of life: Scoping review

According to the 36-Item Short Form Health Survey questionnaire developers, a global measure of health-related quality of life such as the "SF-36 Total/Global/Overall Score" cannot be generated from the questionnaire. However, studies keep on reporting such measure. This study aimed to evaluate the frequency and to describe some characteristics of articles reporting the SF-36 Total/Global/Overall Score in the scientific literature. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses method was adapted to a scoping review. We performed searches in PubMed, Web of Science, SCOPUS, BVS, and Cochrane Library databases for articles using such scores. We found 172 articles published between 1997 and 2015; 110 (64.0%) of them were published from 2010 onwards; 30.0% appeared in journals with Impact Factor 3.00 or greater. Overall, 129 (75.0%) out of the 172 studies did not specify the method for calculating the "SF-36 Total Score"; 13 studies did not specify their methods but referred to the SF-36 developers' studies or others; and 30 articles used different strategies for calculating such score, the most frequent being arithmetic averaging of the eight SF-36 domains scores. We concluded that the "SF-36 Total/Global/Overall Score" has been increasingly reported in the scientific literature. Researchers should be aware of this procedure and of its possible impacts upon human health.

Does local lavage influence functional recovery during lumber discectomy of disc herniation?: One year's systematic follow-up of 410 patients

Lumbar disc herniation (LDH) is a common disease and lumbar discectomy is the most common surgical procedure carried out for patients with low back pain and leg symptoms. Although most researchers are focusing on the surgical techniques during operation, the aim of this study is to evaluate the effect of local intervertebral lavage during microdiscectomy.In this retrospective study, 410 patients were operated on by microdiscectomy for LDH during 2011 to 2014. Retrospectively, 213 of them (group A) accepted local intervertebral irrigation with saline water before wound closure and 197 patients (group B) only had their operative field irrigated with saline water. Systematic records of visual analog scores (VAS), Oswestry disability Index (ODI) questionnaire scale scores, use of analgesia, and hospital length of stay were done after hospitalization.The majority (80.49%) of the cases were diagnosed with lumber herniation at the levels of L4/5 and L5/S1. Fifty-one patients had herniations at 2 levels. There were significant decreases of VAS scores and ODI in both groups between preoperation and postoperation of different time points. VAS scores decreased more in group A than group B at early stage of postoperation follow-up. However, there were no statistically significant differences between 2 groups in using analgesia, VAS and ODI up to 1 month of follow-up.Microdiscectomy for LDH offers a marked improvement in back and radicular pain. Local irrigation of herniated lumber disc area could relief dick herniation-derived low back pain and leg radicular pain at early stage of post-operation. However, the pain relief of this intervention was not noticeable for a long period.

Predicting epidural steroid injections with laboratory markers and imaging techniques

BACKGROUND CONTEXT

Epidural steroid injections (ESIs) have been used for a number of years in the treatment of radicular pain caused by nerve root impingement or stenosis after failed conservative treatments with oral medications, physical therapy, and lifestyle modifications.

PURPOSE

The purpose of this study was evaluation of predictive tools for ESI outcomes in treating radicular pain.

STUDY DESIGN

This was a comprehensive, systematic review of the prognostic accuracy of certain predictive methods used to determine ESI outcomes.

METHODS

Fifty articles were obtained via the PubMed database, using keywords and cross-referencing works cited. Inclusion criteria included patients with radicular pain, analysis of a specific prediction tool, and outcomes measured by improvement in pain and/or function. Exclusion criteria included literature review articles and animal or cadaver studies. Eight articles studying imaging techniques or laboratory markers as prediction tools underwent quality evaluation and evidence classification based on the 2011 American Academy of Neurology Clinical Practice Guideline Process Manual.

RESULTS

For patients with radicular pain, there is insufficient evidence to either support or refute the prognostic accuracy of spinal stenosis seen on imaging in determining epidural steroid outcomes (two Class IV studies). It is possible that low-grade nerve root compression as seen on lumbar magnetic resonance images does predict short-term reduction in pain after transforaminal ESI (Class II and III studies). For patients with lumbar radicular pain, there is both insufficient and conflicting evidence that either supports or refutes prognostic accuracy of high-sensitivity C-reactive protein in determining epidural steroid outcomes (two Class III studies). It is probable that interferon gamma (IFN-γ) more than 10 pg/mL from epidural lavage is predictive of short-term pain reduction after lumbar ESI (single Class I study). There is insufficient evidence that either supports or refutes prognostic accuracy of fibronectin-aggrecan complex from epidural lavage to determine epidural steroid outcome (single Class IV study).

CONCLUSIONS

Predictive tools for ESI outcomes, such as nerve root compression grading and inflammatory markers, particularly, elevated IFN-γ from epidural lavage fluid, seem promising in the future. At this time, future research is needed with a larger sample size, broader spectrum of patients, and a more defined system of outcome measurements at standardized follow-up periods before practice recommendations can be made.

Role of electrodiagnosis in patients being considered for epidural steroid injections

Electrodiagnostic (EDX) evaluation, and, more specifically, electromyography (EMG), has a well-established role in the diagnostic confirmation of cervical and lumbar radiculopathy. The role of EMG in prognostication, however, is less established and remains a topic of debate. The purpose of this article is to evaluate the diagnostic and prognosticating role of EMG in cervical and lumbar radiculopathies, and to assess the utility of EMG in predicting outcomes after epidural steroid injections (ESI). A review of the existing literature strongly supports a prognosticating role for EDX in predicting outcomes after lumbar ESI in lumbosacral radiculopathies (LSR). Although limited research regarding outcome prediction after cervical ESI in cervical radiculopathies has been performed, no study has specifically evaluated the utility of EMG in predicting outcomes for cervical ESI, and this topic requires further investigation. An EDX evaluation can provide clinicians with accurate and reliable diagnostic information (level I or level II evidence) in the evaluation of patients with lumbosacral radiculopathies, and can provide more valid prognostic information (level I evidence) regarding potential benefits of lumbar ESI. An EDX evaluation, therefore, can enhance a clinician's ability to advise patients on the most appropriate and efficacious evaluation and management plan for the treatment of painful radiculopathies.

Does a fibronectin and aggrecan complex play a role in painful vertebral disks?

OBJECTIVE

To determine the presence of a fibronectin-aggrecan complex (FAC) in the disk space of persons with chronic low back pain as relates to provocative diskography.

DESIGN

A single-center prospective consecutive case series.

SETTING

A single private practice setting.

PATIENTS

Thirty-seven patients with symptomatic degenerative disk disease of the cervical, thoracic, or lumbar spine undergoing provocative diskography to identify a source of pain.

METHODS

Diskographic lavage for analysis was simultaneously performed at each disk level injected during diskography.

MAIN OUTCOME MEASURES

Visual analog scale (VAS) pain scores, Pfirrmann magnetic resonance imaging grade, and biochemical analysis of disk material were statistically analyzed.

RESULTS

A total of 105 levels in 37 patients had a complete set of data (mean age 43.2 ± 11.9 years; 15 male/22 female). The FAC was present in 43 of 108 levels and in at least one level in 25 of 37 patients. The Pfirrmann magnetic resonance imaging grade did not differ between complex-positive and negative levels (P = .125), nor did the intraoperative VAS (IO-VAS) score for pain by level (P = .206). A significant but loose correlation was found between Pfirrmann grade and IO-VAS (R(2) = 0.4, P < .001), but no significant correlation was found between VAS or IO-VAS and complex concentration (R(2) = 0.08, P = .11 and R(2) = 0.003, P = .5).

CONCLUSIONS

The FAC was identified in some painful disks by diskography. There was no significant correlation between the Pfirrmann grade or pre/intraoperative pain scores during diskography and complex concentrations within the disk measured by disk lavage.

Cytokine expression in the epidural space: a model of noncompressive disc herniation-induced inflammation

STUDY DESIGN

Animal study.

OBJECTIVE

Development of an animal model for the study of biochemical changes that occur in the epidural space after intervertebral disc herniation.

SUMMARY OF BACKGROUND DATA

Although strong evidence for an inflammatory component exists, the biochemical processes underlying pain after disc herniation remain unknown.

METHODS

Epidural lavage was performed in 48 rats after L5 dorsal root ganglion exposure at baseline and 3, 6, or 24 hours after placement of autologous nucleus pulposus (NP) (N = 15), saline (N = 15), or NP + an interferon-γ antibody (anti-IFN-γ; N = 18) directly onto the dorsal root ganglion. Multiplex assays quantifying interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor α (TNF-α), IFN-γ, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were performed. NP (N = 7) was also analyzed for these cytokines by placing NP into saline and measuring the relative concentration.

RESULTS

Cytokines measured low at baseline (0-100 pg/mL) in all groups. Compared with saline, NP application caused IL-6 elevation, peaking at T = 3 hours, that was prevented by anti-IFN-γ. NP induced elevation of TNF-α, peaking at T = 24 hours and was prevented by anti-IFN-γ. IFN-γ was elevated after NP at T = 3 hours and T = 24 hours. IL-1α was similar after saline versus NP. The concentrations of IL-1β and IL-10 were elevated at T = 3 hours, 6 hours, and 24 hours in all groups without between-groups difference. The level of IL-4 peaked at T = 3 hours in the NP group and was different than saline and NP + anti-IFN-γ groups, but the time effect was insignificant. There was no change for GM-CSF. The concentration of cytokines measured in normal NP was less than 2 pg/mL for all cytokines except TNF-α.

CONCLUSION

In this model of acute noncompressive disc herniation, NP caused the elevation of epidural IL-6, TNF-α, and IFN-γ--all attenuated by IFN-γ blockade. IL-1β and IL-10 were both significantly elevated by saline alone and their response was not prevented by IFN-γ blockade. This model may prove useful for the study of the biochemical processes by which NP induces inflammation-induced nerve root irritation and radiculopathic pain.

Clinical outcomes of cervical radiculopathy following epidural steroid injection: a prospective study with follow-up for more than 2 years

STUDY DESIGN

A prospective clinical outcome study.

OBJECTIVE

To analyze clinical outcome and prognostic factors of the epidural steroid injection (ESI) for cervical radiculopathy (CR) patients who were considered surgical candidates.

SUMMARY OF BACKGROUND DATA

The clinical outcomes and prognostic factors of ESI for CR have not been consistently reported, and there has been no prospective study with long-term follow-up.

METHODS

ESI was administered in 98 patients (mean age = 50.1 yr, follow-up = 40.4 mo) with CR without major neurological deficit. A total of 3 or fewer ESIs were administered, using either the interlaminar or transforaminal technique. The patients were divided into 2 groups: those who did not have surgery and those who underwent surgery at the last follow-up. We analyzed statistical difference of relevant clinical (sex, age, duration of symptom, previous episode of CR, visual analogue scale [VAS] of arm pain, etc.), radiological factors (soft disc vs. hard disc, central disc vs. foraminal disc, single segment involvement vs. multiple segment involvement, degree of neural compression and degeneration, etc.) and clinical outcomes (VAS of arm pain, Odom's criteria, and neck disability index) between the 2 groups.

RESULTS

The patients received mean 1.8 ESI treatments. At the final follow-up, 79 of the patients (80.6%) did not undergo surgery, whereas the other 19 patients (19.4%) underwent surgery. Of the clinical factors, recurred CR (15.2% vs. 42.1%, P = 0.022) and mean VAS score of arm pain before (6.1 vs. 8.2, P = 0.000) and after ESI (2.8 vs. 6.9, P = 0.000) were significantly different between both groups. Radiological factors and outcome parameters showed no significant difference.

CONCLUSION

In more than 80% of patients with CR who were surgical candidates, surgery was avoided using ESI. The significant factors predisposing failure of ESI were intensity of symptom and a previous episode of CR. ESI is therefore considered a safe and effective treatment to choose before undergoing surgery.

Is the fibronectin-aggrecan complex present in cervical disk disease?

OBJECTIVE

To investigate the presence of inflammatory cytokines and the fibronectin-aggrecan complex (FAC) in persons undergoing surgical treatment for cervical radiculopathy caused by disk herniation.

DESIGN

Single-center, prospective, consecutive case series.

SETTING

A single large academic institution.

PATIENTS

A total of 11 patients with radiculopathic pain and magnetic resonance imaging findings positive for disk herniation elected to undergo single-level cervical diskectomy. METHODS OR INTERVENTIONS: Lavage was performed by needle injection and aspiration upon entering the disk space for fluoroscopic localization before diskectomy.

MAIN OUTCOME MEASUREMENTS

The lavage fluid was assayed for pH and the FAC, as well as for the cytokines interleukin-6 (IL-6), interferon-γ, monocyte chemotactic protein (MCP), and macrophage inhibitory protein-1β.

RESULTS

The subjects were 7 women and 4 men with a mean age of 50.6 years (SE 9.7; range, 36-70 years). The mean concentrations (SE; range) in picograms per milliliter were 7.9 (4.4; 0-44) for IL-6, 25.3 (15.5; 0-159) for interferon-γ, 16.1 (11.9; 0-121) for MCP, and 6.1 (2.8; 0-29) for macrophage inhibitory protein-1β. The optical density of the FAC at 450 nm was 0.151 (0.036; 0.1-0.32), and the pH was 6.68 (0.1; 6.10-7.15). Statistically significant correlations were found between MCP and FAC (P = .036) and between FAC and pH (P = .008).

CONCLUSIONS

Biochemical analysis of injured cervical intervertebral disks reveals the presence of inflammatory markers such as MCP, fragments of structural matrix proteins such as FAC, and a correlation with pH. Further evaluation of the FAC as a potential diagnostic biomarker or therapeutic target is warranted in the cervical spine.