Septic Hip Arthritis in Patients with Osteonecrosis of Femoral Head: Two Cases Report and Review of the Literature

Background: In patients with osteonecrosis of femoral head (ONFH), septic arthritis of the hip is rare, especially in the absence of factors likely to cause infection, which are often ignored by surgeons. Methods: Two patients seen at our hospital who had ONFH and concomitant septic arthritis of the hip joint were selected for inclusion in the study. Results: The clinical course suggests that ONFH developed prior to the hip infection. The two patients were not immune-compromised, and no remote septic focus was identified. The 2 patients, clinical manifestations of infection included fever and elevated white blood cell count. Elevated levels of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were observed in all 2 patients. In all patients, the results of hip magnetic resonance imaging (MRI) indicated hip infection. For 1 patients, culturing joint fluid revealed the presence of bacteria. In the second case, joint fluid was not cultured. In each case, the hip was debrided, and a spacer made of bone cement and containing vancomycin was implanted in the hip. Intravenous antibiotics were administered for 6 weeks postoperatively. There was no recurrence of infection, and total hip arthroplasty (THA) was performed 6 months after the operation. Conclusions: Septic hip is rare but exist in patients with ONFH. Elevated ESR and CRP contributed to the initial diagnosis; the results of hip MRI help to confirm the diagnosis. Overall, THA was an effective treatment.