Title: Charcot knee mimicking erysipelas A 85-year-old diabetic man presented to the emergency department for a 2-week history of a limb pain associated with right leg edema. Physical examination revealed a temperature of 37.5°C, a marked swelling in the right limb with an erythematous overlying skin. The patient had limitation of both passive and active range of motion of right knee. Laboratory tests showed inflammation (C-reactive protein (CRP) 179 mg/l). Blood cell counts were normal. The diagnosis of erysipelas was made and antibiotic therapy (amoxicillin–clavulanate) was started. Four days later, fever appeared and we noted an increase in the oedema and the CRP was 218mg/l. A leg abscess was suspected. The surgical flattening of the abscess was indicated. Per-operative examination showed a fracture of the fibular head associated with excessive bone loss at the medial plateau of the tibia.X-ray showed destructive femoral condyle and signs of knee subluxation and bone fragmentation (figure 1A). Computer tomography scanning of the right knee confirmed the femorotibial dislocation and the bony fragmentation, with formation of debris seen as intra-articular loose bodies (figure B). Considering these aspects, the most likely diagnosis was Charcot Knee. The patient underwent a trial of conservative treatment and then we suggested a custom-made hinged knee brace for daily use.Neuropathic arthropathy, or Charcot joint is a systemic disease that generates pathological changes in the musculoskeletal system, causing instability, dislocations, and deformities [1]. The literature on CK remains sparse, with most publications being case reports [1]. Diabetes mellitus is the most common etiology and feet and ankles are the most commonly involved joints [2]. Charcot knee is rare, and observed in 6% of patients with diabetes [3], physicians should be aware of this complication. Any patient with peripheral neuropathy, presenting with a red and erythematous knee should be reviewed for CK.
