We report a 59 years old man with a suspicious sexual contact between 3-5years ago, who developed repeated painless swelling in his left knee, and a progressive destructiveosteitis in his tibia. After rejecting other pathologies, the diagnosis arrived by the high treponemicactivity proved by specific serology and the clinical recovery with antibiotictreatment. The swelling disappeared and only the residual deformity persisted. We didn't findany treponema in the biopsy.

We report a 59 years old man with a suspicious sexual contact between 3-5years ago, who developed repeated painless swelling in his left knee, and a progressive destructiveosteitis in his tibia. After rejecting other pathologies, the diagnosis arrived by the high treponemicactivity proved by specific serology and the clinical recovery with antibiotictreatment. The swelling disappeared and only the residual deformity persisted. We didn't findany treponema in the biopsy.