Antimicrobial treatment of Brucella-infected prosthetic knee with sinus tract: A case report

RATIONALE: Brucella infection of prosthetic joints is exceedingly rare. Current literature indicates that cases complicated by abscess and sinus tract, but without prosthetic loosening, have uniformly been managed with either debridement, antibiotics, and implant retention or revision arthroplasty combined with antimicrobial therapy. These approaches impose a significant economic burden on healthcare systems. Herein, we present a case of Brucella-infected prosthetic knee with sinus tract formation and radiographically stable components that was successfully cured with antimicrobial therapy alone. PATIENT CONCERNS: A 63-year-old Chinese woman underwent total knee arthroplasty 13 months prior for osteoarthritis. Subsequently, she developed a periprosthetic joint infection and received treatment at a local hospital. Due to atypical clinical symptoms, inconclusive radiographic findings, and negative bacterial cultures, arthrotomy with drainage, exchange of the tibial polyethylene insert, and empirical anti-tuberculosis therapy were performed. However, the infection failed to resolve. DIAGNOSES: The patient presented with knee swelling, pain, purulent drainage, and a sinus tract following total knee arthroplasty. A positive standard tube agglutination test, coupled with a history of chronic sheep exposure, confirmed the diagnosis of Brucella infection. INTERVENTIONS: Since the patient's prosthesis showed no loosening, a dual regimen of doxycycline and rifampicin was administered for 3 months. OUTCOMES: The sinus tract healed completely, standard tube agglutination test serology reverted to negative, and full restoration of knee function was recovered. LESSONS: For patients definitively diagnosed with Brucella periprosthetic joint infection and radiographically stable implants, conservative management with antimicrobial therapy alone should be considered as a viable initial treatment option, irrespective of the presence of a sinus tract. Knee prosthesis removal and spacer implantation may be deferred in such cases.