Fusobacterium Nucleatum is an anaerobic commensal microorganism present in the oral cavity and some mucousmembranes with great capacity to form biofilm. In the literature, only one case of acute periprosthetic infection of the kneeby Fusobacterium Nucleatum has been reported, providing the second case. A 72-year-old man presented with an acuteperiprosthetic infection by fusobacterium nucleatum after a second time of a prosthetic knee replacement. Debridementand spacer changes were performed up to 4 times, associating parenteral antibiotic treatment. After ensuring the absenceof infection, a modular revision knee prosthesis with stems was placed, with a satisfactory evolution after two years.Currently he has preserved ambulation, joint balance of 0º-50º and is free of infection. Fusobacterium Nucleatum infectionis very rare, but aggressive and difficult to resolve, recommending two-stage replacement in acute infection and adequateantibiotic treatment to offer curative treatment.

Fusobacterium Nucleatum is an anaerobic commensal microorganism present in the oral cavity and some mucousmembranes with great capacity to form biofilm. In the literature, only one case of acute periprosthetic infection of the kneeby Fusobacterium Nucleatum has been reported, providing the second case. A 72-year-old man presented with an acuteperiprosthetic infection by fusobacterium nucleatum after a second time of a prosthetic knee replacement. Debridementand spacer changes were performed up to 4 times, associating parenteral antibiotic treatment. After ensuring the absenceof infection, a modular revision knee prosthesis with stems was placed, with a satisfactory evolution after two years.Currently he has preserved ambulation, joint balance of 0º-50º and is free of infection. Fusobacterium Nucleatum infectionis very rare, but aggressive and difficult to resolve, recommending two-stage replacement in acute infection and adequateantibiotic treatment to offer curative treatment.