Abstract
Pyogenic spondylodiskitis rarely originates in the facet joint. Differential diagnosis of pyogenic facet joint infection （PFJI） has not been fully discussed. We investigated CT and MRI findings in five cases of PFJI with comparing of tuberculous and non-infectious facet joint arthritis. We assessed bone destruction and calcification of soft tissue around the involved facet joint on CT, while we also assessed signal intensity changes of adjacent intervertebral disc and facet joints, extraosseous abscess formation, and extent of contrast enhancing lesion on MRI. Only unilateral facet joint was involved in the PFJI with concomitant abscess formation. Bilateral facet joints were involved in the non-infectious facet joint arthritis. Faint calcification around the joint and ill-defined contrast enhancement were observed in this arthritis. Marked bone destruction was observed in the tuberculous arthritis. Unilateral facet joint lesion accompanying with extraosseous abscess formation is characteristic of PFJI.
