Elsevier

The Spine Journal

Volume 10, Issue 3, March 2010, Pages 200-208
The Spine Journal

Clinical Study
Computed tomography–evaluated features of spinal degeneration: prevalence, intercorrelation, and association with self-reported low back pain

https://doi.org/10.1016/j.spinee.2009.10.018Get rights and content

Abstract

Background context

Although the role of radiographic abnormalities in the etiology of nonspecific low back pain (LBP) is unclear, the frequent identification of these features on radiologic studies continues to influence medical decision making.

Purpose

The primary purposes of the study were to evaluate the prevalence of lumbar spine degeneration features, evaluated on computed tomography (CT), in a community-based sample and to evaluate the association between lumbar spine degeneration features. The secondary purpose was to evaluate the association between spinal degeneration features and LBP.

Study design

This is a cross-sectional community-based study that was an ancillary project to the Framingham Heart Study.

Sample

A subset of 187 participants were chosen from the 3,529 participants enrolled in the Framingham Heart Study who underwent multidetector CT scan to assess aortic calcification.

Outcome measures

Self-report measures: LBP in the preceding 12 months was evaluated using a Nordic self-report questionnaire. Physiologic measures: Dichotomous variables indicating the presence of intervertebral disc narrowing, facet joint osteoarthritis (OA), spondylolysis, spondylolisthesis, and spinal stenosis and the density (in Hounsfield units) of multifidus and erector spinae muscles were evaluated on CT.

Methods

We calculated the prevalence of spinal degeneration features and mean density of multifidus and erector spinae muscles in groups of individuals with and without LBP. Using the χ2 test for dichotomous and t test for continuous variables, we estimated the differences in spinal degeneration parameters between the aforementioned groups. To evaluate the association of spinal degeneration features with age, the prevalence of degeneration features was calculated in four age groups (less than 40, 40–50, 50–60, and 60+ years). We used multiple logistic regression models to examine the association between spinal degeneration features (before and after adjustment for age, sex, and body mass index [BMI]) and LBP, and between all degeneration features and LBP.

Results

In total, 104 men and 83 women, with a mean age (±standard deviation) of 52.6±10.8 years, participated in the study. There was a high prevalence of intervertebral disc narrowing (63.9%), facet joint OA (64.5%), and spondylolysis (11.5%) in the studied sample. When all spinal degeneration features as well as age, sex, and BMI were factored in stepwise fashion into a multiple logistic regression model, only spinal stenosis showed statistically significant association with LBP, odds ratio (OR) (95% confidence interval [CI]): 3.45 [1.12–10.68]. Significant association was found between facet joint OA and low density of multifidus (OR [95% CI]: 3.68 [1.36–9.97]) and erector spinae (OR [95% CI]: 2.80 [1.10–7.16]) muscles.

Conclusions

Degenerative features of the lumbar spine were extremely prevalent in this community-based sample. The only degenerative feature associated with self-reported LBP was spinal stenosis. Other degenerative features appear to be unassociated with LBP.

Introduction

Evidence & Methods

The population prevalence of degenerative findings on advanced imaging can provide important information regarding specificity of some findings.

This study, using computer tomography in a small cohort of the Framingham Heart Study, confirms previously reported information in cadaveric, plain radio-graphic, and MRI studies. Gross degenerative findings appear to be very common and, in the absence of spinal stenosis (<10 mm), their correlation to clinical back pain syndromes are poor.

Clearly most degenerative findings are not associated with serious back pain illness. This study provides some estimate of baseline pre-test probabilities in a community-based sample with a broad spectrum of symptoms. Pre-test probabilities calculated for a specific clinical population (e.g. those with low back pain, with radiculopathy, with neurogenic claudication) may further clarify diagnostic-test utility of specific findings in specific patient presentation patterns.

—The Editors

Low back pain (LBP) is a pervasive problem that affects two-thirds of adults at some time in their lives [1]. Back pain and its sequelae place an enormous burden on society, health-care systems, and the economies of developed countries [2]. Despite the high prevalence of LBP, little is known about the pathogenesis of this complaint. In clinical practice, some clinicians routinely request imaging to confirm their diagnosis and provide reassurance. Others limit the use to patients who require interventional treatment or who have signs of potentially serious diseases, for they argue that imaging could provide misleading information, generate unnecessary anxiety, and lead to inappropriate treatment [3], [4]. The clinical literature includes multiple reports of the high prevalence of degenerative spinal changes in asymptomatic individuals and does not support a significant relationship between such changes and the development of LBP [5], [6], [7].

Although the role of radiographic abnormalities in the etiology of nonspecific LBP is unclear, the frequent identification of these features on radiologic studies continues to influence medical decision making with respect to additional evaluation and selection of treatment options. In primary care settings, the most common spine imaging tests for assessing LBP are plain radiography, computed tomography (CT), magnetic resonance imaging (MRI), and bone scanning. Low cost and ready availability make plain radiography the most common of these [8], [9]. However, a systematic review of published observational studies found no strong evidence supporting the presence of a causal relationship between radiographic findings and nonspecific LBP [10]. Clinical studies have consistently failed to demonstrate a significant relationship between spinal degeneration and LBP based on data from plain radiographic testing. However, the poor quality of imaging studies has been cited as a potential reason that the relationship between degeneration and LBP could not be defined.

In contrast to radiography, CT optimizes delineation of bony architectural details that are particularly relevant to degenerative disease (Figure). These details include end plate irregularity and sclerosis, spinal stenosis, facet joint osteoarthritis (OA), spondylolysis, and spondylolisthesis. Abnormalities that can be demonstrated and categorized by CT include osteophyte formation; hypertrophy of articular processes; articular cartilage thinning; vacuum phenomenon in joints and discs; synovial and subchondral cysts; and calcification of the joint capsule, vertebral end plates, and ligaments [11], [12], [13]. A review of the clinical literature revealed no CT-based studies evaluating the prevalence of structural abnormalities in the spine and their relation to LBP in an unselected population-based cohort.

The aim of the present study was to evaluate the association between degenerative features of the lumbar spine evaluated on CT and self-reported LBP in a community-based sample. Furthermore, we also examined the relation between different lumbar spine degeneration features including intervertebral disc narrowing, facet joint OA, spondylolysis, spondylolisthesis, and spinal stenosis and the density of multifidus and erector spinae muscles.

Section snippets

Study design

This is a cross-sectional community-based study that was an ancillary project to the Framingham Heart Study.

Sample

This project was an ancillary project to the Framingham Heart Study. This study began in 1948 as a longitudinal population-based study of the causes of heart disease. Initially, 5,209 men and women living in Framingham, MA, were enrolled. In 1971, 5,124 offspring (and their spouses) of the original cohort were entered into the Offspring cohort. In 2002, 4,095 men and women who were

Results

Results of reliability tests (kappa statistics) were as follows: The intraobserver reliability for disc narrowing varied at different spinal levels between 0.84 and 0.90. The interobserver reliability for disc narrowing ranged from 0.78 to 0.88. The intraobserver reliability for grading different facet joint OA indices varied between 0.64 and 0.91 and the interobserver reliability ranged from 0.59 to 0.94. The intraobserver reliability for identification of spondylolysis was 1.00 and the

Discussion

This is the first cross-sectional study to describe simultaneously the prevalence of comprehensive CT-evaluated spinal degeneration features in a community-based population. The results show a high prevalence of intervertebral disc narrowing (63.9%) and facet joint OA (64.5%) in the studied sample. The reported prevalence of disc space narrowing is slightly higher than that previously reported in MRI studies [32], [33], [34], [35]. In those studies, the reported prevalence of disc space

Conclusions

This ancillary project to the Framingham Heart Study is the first community-based study of the prevalence of CT-evaluated lumbar spinal degeneration features in an unselected population. It is confirmed that degenerative features of the lumbar spine are extremely prevalent in the general community. A statistically significant association was found between facet joint OA and the density of multifidus and erector spinae. The only degenerative feature associated with self-reported LBP was spinal

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    FDA device/drug status: not applicable.

    Author disclosures: LK (research support, Arthritis Foundation Postdoctoral Grant); DHK (consulting fees, Medtronic, DePuy, Stryker, Zimmer, Synthes; research support, New England Baptist Hospital); AG (stock ownership, Synarc; President, BICL, LLC); DJH (research support, Donjoy, Wyeth, Merck, Pfize, Stryke).

    Supported by the National Heart, Lung and Blood Institute's Framingham Heart Study contract (No. N01-HC-25195) for the recruitment, enrollment, and examination of the Offspring and Third Generation cohorts and the imaging by computed tomography scan.

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