Delayed presentation of septic arthritis of a lumbar facet joint after diagnostic facet joint injection.

We report the case of a 46-year-old, otherwise healthy, man with chronic lower back pain and no evidence of nerve root compression who underwent diagnostic facet joint injections to assist in establishing where his pain sources were located and to try to help his spinal rehabilitation program. He presented with a facet joint infection 2 months after injection, in a manner that was indistinguishable from an acute intervertebral disc herniation. The diagnosis was confirmed on magnetic resonance imaging, and he was successfully treated with surgical debridement and antibiotics. Septic arthritis of a lumbar facet joint with an associated paraspinal abscess is a rare complication of facet joint infiltration with only two similar cases reported in the literature. We propose that this diagnosis be considered in patients who have undergone diagnostic facet joint injection who subsequently deteriorate with back and leg pain without another apparent cause.