Synovial cysts of the lumbar facet joints in a symptomatic population - Prevalence on magnetic resonance imaging

Study Design. A retrospective review of 303 MRI scans of the lumbar spine was conducted. Objectives. To determine the prevalence of lumbar facet joint synovial cysts arising from the joints anteriorly and posteriorly. To examine the association of these cysts with facet joint osteoarthritis and degenerative disc disease. Summary of Background Data. Sporadic reports of such cysts exist as do limited studies describing the prevalence of symptomatic anterior facet joint synovial cysts. However, the overall prevalence of lumbar facet joint synovial cysts has not been formally studied, and the mechanism of formation of these cysts is not fully understood. Methods. One observer undertook a review of MRI of the lumbar spine from one facility in a series of 303 patients referred mostly for back pain or radiculopathy. The presence of lumbar facet joint synovial cysts, their relationship to the facet joint, the degree of associated facet joint osteoarthritis, the presence of spondylolisthesis, and the degree of associated disc degeneration were recorded. Results. Seven anterior cysts ( prevalence = 2.3%) were identified, only two of which did not clearly cause nerve root compression. Twenty-three posterior cysts in 22 patients ( prevalence = 7.3%) were identified. Statistically significant associations with increased frequency and severity of facet joint osteoarthritis and with spondylolisthesis were demonstrated compared to patients without cysts. Conclusions. Both anterior and posterior lumbar facet joint synovial cysts are rare. Posterior cysts are more common than anterior cysts. Both types of cysts are related to facet joint osteoarthritis but not to disc disease.