A particular form of septic arthritis: septic arthritis of facet joint.

Only about 40 cases of septic arthritis of the facet joints have been reported to date. We report 6 new cases including 2 at the cervical spine, which is rarely involved. Mean age was 61.5 years; there were 5 men and 1 woman. Spinal pain and stiffness, fever, and asthenia were the presenting manifestations. Laboratory tests consistently showed inflammation. Among classical risk factors for infection, only noninsulin-dependent diabetes was noted, in a single patient. Mean time to the diagnosis was 42 days. Discitis, a far more common condition, was considered initially, and early radiographs were of limited diagnostic assistance. Radionuclide bone scans identified the site of the infection and served to look for other foci. Magnetic resonance imaging was effective in confirming the diagnosis at an early stage and in looking for local spread (muscles, epidural space, and disk). L3-L4 was involved in 3 patients, C4-C5 in 2, and L4-L5 in 1. Direct inoculation during mesotherapy sessions was the cause in 1 patient. Cultures of blood and needle biopsy samples were positive in all 6 cases; Staphylococcus aureus was the causative agent in 3 patients. The risk of local and systemic complications governs the prognosis of facet joint infection. Of our 6 patients, 4 experienced complications: there was 1 case each of discitis, epidural infection, endocarditis, and septic arthritis of the acromioclavicular joint. Fatal multiple organ dysfunction occurred in 1 patient. In the other 5 patients, antimicrobial therapy and protection from weight-bearing for 3 months ensured a favorable outcome.