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.