Septic Arthritis of a Posterior Lumbar Facet Joint in an Infant

Abstract

: Case report. : To describe a case of septic arthritis of the facet joint in an infant. : To our knowledge, no more than 50 cases of septic arthritis of a facet joint are reported in literature, including only 4 cases in children and none in infants. : A girl of age 18 months presented with a fever pattern of 4 days evolution, right lumbar paravertebral tumefaction with local inflammatory signs and limping related to pain with weight-bearing on the right lower extremity. The mother reported a pharyngeal infection 2 weeks earlier.Conventional radiology showed no alterations. MR and scintigraphy with radioactivity-marked leukocytes showed affectation only of the posterior facet joint of right L4-L5, without associated collections. Blood and urine cultures were negative. The diagnosis was established as right L4-L5 septic arthritis of a lumbar facet joint, probably of hematogenous origin. : The fever pattern and the limp disappeared in 24 hours with wide-spectrum empirical intravenous antibiotherapy. Although no microorganism was isolated, the good response to the empirical treatment and the background of pharyngeal infection point to a hematogenous dissemination by Staphylococcus aureus or Streptococcus spp. : Septic arthritis of a facet joint does not differ clinically from other spinal infections and its incidence is possibly underestimated in favor of other more common entities. Only imaging techniques can differentiate the affected structures and establish the exact diagnosis.MR allows the detection in initial stages, delimits the affectation and extension through the soft tissues, and rules out other more common entities such as discitis. Scintigraphy and SPECT can detect other active foci and be useful in the follow-up.The result achieved with antibiotic treatment in early stages is usually satisfactory. Surgical debridement is only necessary when associated purulent collections appear. From the pediatric point of view, spinal infections should also be taken into consideration within the differential diagnostic of limp in children.