Septic arthritis of the hip associated with atopic dermatitis. A case report

We report a case of septic arthritis of the hip associated with atopic dermatitis. A 15-year female felt a pain in the right hip with unknown cause on May 11, 1998. The pain subsequently became aggravated, and she was admitted to our hospital on May 18. She has had atopic dermatitis since 4 years of age. She showed generalized dermatitis with desquamation and numerous scratch marks. A culture of both skin and joint fluid revealed Staphylococcus aureus. Physical examination revealed tenderness in Scarpa triangle and restricted range of motion. Immunological serology showed an increase in eosinophils and immunoglobulin E, and a decreased reaction of lymphocyte blastoid transformation. Computed tomography (CT) and MRI showed a joint effusion in the right hip. She was diagnosed as having septic arthritis of the hip. Intravenous drip of Cefazolin of 2g was started on the first day of hospitalization and joint irrigation was done on the second day. CRP became negative at 4 weeks, but joint effusion was shown on CT. Additional joint irrigation with Amicamycin (200 mg) was done. As the joint fluid culture became negative, range of motion exercises were started at 6 weeks. She was discharged with a long-leg brace applied at 8 weeks. At 13 months after onset, she had complete relief of the pain and normal activities of daily living. No destructive changes in the hip were found on X-ray examination or MRI. In the present case, an abnormal immune system associated with atopic dermatitis as well as the habit of scratching eruptions may have led to hematogenous spread of skin infection, and caused septic arthritis of the hip.