Septic arthritis of the posterior lumbar joints is extremely rare. The
clinical picture of this unusual site of infection can easily lead to
confusion with spondylodiscitis which is more commun. We report a cas
e of a 50-year-old women with Staphylococcus aureus septic arthritis o
f the left L5-S1 lumbar facet joint. CT scan was helpful to establish
the diagnosis and to guide the percutaneous needle biopsy.