The lumbar facet joints (more precisely known as zygapophysial joints) are one of several potential sources of lower back and referred buttock and leg pain. The other pathoanatomic sources include the discs, ligaments, sacroiliac joints, and muscles. Serious spinal pathology (cancer, infections, fractures, bone weakening disease, and systemic inflammatory disease such as ankylosing spondylitis) and visceral referral form a second group of back pain causation. Once this second grouping has been ruled out and the patient is appropriate for mechanical assessment, there are studies that have demonstrated clinical indicators for disc, sacroiliac joint and hip disorders. There are no clear clinical indicators for identifying facet joints as the primary source for lower back pain.
X-rays, CT scans and MRI’s have not shown correlation between imaging findings and low back pain; they have been abnormal in asymptomatic subjects and normal in symptomatic ones. The reference standard for identifying the facet joint as the sole source of low back pain is diagnostic injection of local anesthetic into the facet joint or the lumbar medial branch nerve which results in total or near total ablation of the patient’s familiar pain. A second confirmatory block follows to screen out false positive responders to the first injection.
Patients who have back pain of facet joint origin confirmed by diagnostic block injections respond favorably to radio frequency neurotomy. As estimates of the prevalence of facet joint pain have ranged from 15 to 40 percent and imaging studies are not typically useful for identifying pain generators in the lumbar spine, the development of accurate clinical examination guidelines could help identify those patients who are the most appropriate candidates to be subjected to invasive diagnostic injections. The purpose of this study was to further investigate previously published clinical criteria indicating low back pain originating from the lumbar facet joints.
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