Spontaneous Pyogenic Facet Joint Infection

Objective To analyze the clinical features, approaches to management, and outcome of spontaneous pyogenic facet joint infection (PFJI) in adults. Patients and methods Case series of 10 adults with microbiologically proven PFJI diagnosed during a 10-year period in a teaching hospital, plus a review of 32 additional cases previously reported (PubMed 1972 to 2003). Patients with prior spinal instrumentation or surgery and injection drug users were excluded. Only cases that were sufficiently detailed to be individually analyzed were included. These 32 cases, together with our 10 patients, form the basis of the present analysis. Results PFJI represented nearly 20% of all spontaneous pyogenic spinal infection diagnosed in our hospital during a 10-year period. This data suggest that PFJI is more common than was previously thought. Of the 42 patients with PFJI, 26 (62%) were men and 16 (38%) were women, with ages ranging from 20 to 86 years (mean age, 59 ± 15 years); 55% of patients were older than 60 years. The most common location of infections was the lumbosacral region (86%). All patients presented with severe back pain; fever was noted in 83% of the cases and neurological impairment in nearly 48%. In 38% of patients a systemic predisposing factor for infection was present; the most common conditions were diabetes mellitus, malignancies, and alcoholism. In almost 36% of cases, one or more concomitant infectious processes due to the same microorganism was found, mainly arthritis, skin and soft-tissue infections, endocarditis, and urinary tract infections. Staphylococcus aureus was the most common etiologic microorganism (86% of cases). Bacteremia was documented in 81% of the cases. The diagnosis of PFJI was based mainly on imaging study findings. Paraspinal and/or epidural extension was frequent (81% of cases), but its presence did not indicate a worse prognosis. Medical treatment alone was usually successful. The overall prognosis of PFJI was good, with a mortality rate of only 2%. The great majority of patients were cured without functional sequelae. Conclusion Incidence data from our institution reveal that PFJI is not a rare condition, representing approximately 20% of all pyogenic spinal infections. This entity should be considered in the differential diagnosis of patients with low back pain, especially in the presence of fever, whatever the patient's immunological status.