Imaging update in arthroplasty

Polymicrobial periprosthetic joint infection and osteomyelitis of the tibia with circumferential abscess and skin ulcer 11 years after total knee arthroplasty

We report the case of a 71-year-old woman with a skin ulcer derived from an abscess around the tibia. The abscess resulted in periprosthetic joint infection and osteomyelitis 11 years after total knee arthroplasty. The first symptom was a skin ulcer of the lower leg. Magnetic resonance imaging revealed a circumferential mass around the proximal tibia. A skin biopsy taken around the ulcer showed thrombosis and degenerated collagen. Contrast-enhanced computed tomography showed a circumferential mass around the proximal tibia with ring enhancement. Biopsies of the skin ulcer and circumferential mass showed an abscess caused by Enterococcus faecium and methicillin-resistant Staphylococcus epidermis. We conducted debridement of the abscess, a gastrocnemius flap and split-thickness skin grafting and a 2-stage revision of the total knee component with a hinged prosthesis. Two years later, the infection did not reoccur and the patient can walk without a cane. This case is unique as abscess around proximal tibia caused necrotic skin ulcer and appearance of abscess was fibrous and different from typical bacterial abscesses containing pus or fluid. Contrast-enhanced computed tomography was effective for differentiation of the pathological condition.