Isolated Septic Arthritis of the Hip Due to Fusobacterium Nucleatum in An Immunocompetent Adult: A Case Report and Review of the Literature.

Introduction: Hip septic arthritis is more common in children than in adults. Staphylococcus aureus and Streptococcus spp. are commonly found in association with septic joints. In contrast, Fusobacterium nucleatum septic arthritis in adults is extremely rare. To the best of our knowledge, only five cases have been reported in the literature in English, and three of them were cases of periprosthetic joint infection. We report a rare case of hip septic arthritis due to F. nucleatum in an immunocompetent adult.

Case Presentation: A 56-year-old Asian man with a history of bilateral Perthes' disease and mild alcoholic liver disease presented to our hospital complaining of worsening right hip pain and difficulty in walking for the previous 3 weeks. On presentation, his temperature was 38.7°C, and laboratory results showed a white blood cell count of 19 200 cells/µL and a C-reactive protein level of 43.56 mg/dL. Hip movements were limited due to pain. Contrast-enhanced computed tomography and magnetic resonance imaging showed fluid retention, suggesting infection. F. nucleatum was detected in the culture test from joint aspirate. Surgical drainage was performed 3 times in combination with antibiotherapy. Finally, we performed two-stage total hip arthroplasty, and the post-operative course was uneventful without implant loosening or infection relapse.

Conclusion: The patient had a history of Perthes' disease and had hip osteoarthritis, which may have contributed to the development of hip septic arthritis. We treated this rare case of hip septic arthritis due to F. nucleatum with two-stage revision surgery and antibiotherapy. Clinicians should be aware that F. nucleatum could be the etiologic agent of hip septic arthritis in an immunocompetent patient.