Septic arthritis of bilateral lumbar facet joints - Report of a case with MRI findings in the early stage

Study Design. A case is reported. Objective. To report and discuss a case of septic arthritis of bilateral lumbar facet joints with contiguous extension into the paraspinal musculature without infection of the vertebral body or disc space. Summary of Background Data. Septic arthritis of a lumbar facet joint is a rare cause of low back pain, and only a few cases have been described. If the condition is not associated with epidural or paraspinal abscess formation and self-limiting, the correct diagnosis may be overlooked. To the author's knowledge, septic arthritis of bilateral facet joints has not been previously described in the literature. Methods. A 72-year-old woman without any systemic illness was hospitalized because of acute severe back pain and high fever. Examination showed local tenderness over the lower lumbar region. Magnetic resonance imaging showed widened facet joints, abscess in the joints, and paraspinal involvement, which aided diagnosis and preoperative planning. Results. The infection did not respond to intravenous antibiotics therapy, so a thorough debridement of the bilateral facet joints was performed. At the latest follow-up assessment, the patient remained afebrile and had a marked reduction of low back pain. Conclusions. Septic arthritis of the lumbar facet joint is a rare cause of low back pain. It is important to ascertain the diagnosis at the earliest possible stage and to start intravenous antibiotics therapy as soon as possible. Magnetic resonance imaging is a quite sensitive method for identifying infection of the lumbar facet joint. Surgical debridement may be necessary if antibiotic therapy fails.