Infection of the ankle joint is a serious problem that can have a debilitating outcome if not identified and treated appropriately.

The purpose of this retrospective study is to present epidemiologic data aimed at better characterising the clinical diagnosis of septic ankle guiding empiric therapy.

All admissions to Los Angeles County+USC Medical Center between 1996 and 2005 were screened to identify patients with ankle infection, shown by a synovial WBC count > 50,000, frank purulence in the joint, or positive synovial culture. Forty-two patients (33 male, 9 female) with a mean age of 44.8 (23 to 67 years) were identified. Twelve out of forty-two patients had indwelling hardware and were excluded from further analysis.

Of the 30 patients with hematogenous septic ankle arthritis, 87% reported ankle pain, 70% ankle swelling, and 50% demonstrated decreased range of motion at the ankle joint. Cultures grew Staphylococcus aureus (43%), streptococci (30%), and gram-negative rods (7%). Twenty-three percent of cases were polymicrobial; no cases of Neisseria gonorrhea were identified. There were 3 cases of M. tuberculosis, and 1 case each of Coccidioides immitis and Aspergillus sp. Forty-four percent of the Staphylococcus aureus were methicillin-resistant (MRSA); no change was observed in prevalence of resistant organisms over time. Only 48% had an elevated WBC count; C-reactive protein and ESR were elevated in 100% of patients. Adjacent osteomyelitis was found in 30% of patients. Open irrigation and debridement was performed in 73% of cases; five patients required multiple surgical procedures and 1 amputation.

Septic ankle arthritis presents non-specifically; a high index of suspicion is essential to ensure prompt identification and treatment. Empiric antibiotic therapy should cover Staphylococcus aureus (including MRSA) and streptococcus. Patients should be evaluated for adjacent osteomyelitis.