Tabetic arthropathy of the knee: A case report

Tabetic arthropathy is a chronic, destructive neurogenic disease, that is considered the late stage of syphilis. The causative agent is Trepanoma pallidum, a spirochete bacterium that is sexually transmitted. It is characterized by extensive destruction and joint deformity in an indolent context. Syphilis serology confirms the diagnosis. Prevention requires early treatment of syphilis with penicillin G. We report the case of a 59-year-old patient with a history of an untreated syphilitic chancre at the age of 32 years who presented with significant joint deformity of the knee that had been evolving for 10 years in the context of joint effusion. A CT scan of the affected knee revealed destruction of the lateral femoral condyle and homolateral tibial plateau, subchondral osteosclerosis, thickening and irregularity of the femoral and tibial cortical bone, marginal exuberant proliferative osteophytes of the medial femoral and superior tibial condyles, and the presence of multiple cystic joint cavities communicating with each other and with the synovium, with thickened walls and multiple loose calcified bodies of different shapes and sizes, resulting in a "bag of bones" appearance. The patient's syphilitic serology was positive, and the diagnosis of tabetic arthropathy was confirmed. This case study aims to raise awareness of this rare manifestation of syphilis, which is becoming rare today, to avoid delays in diagnosis and to limit its complications.