Distal Leg Wear Debris Mass from a Rotating Hinged Knee Prosthesis

An 18-year-old woman presented with a gradually increasing distal leg mass 8 years after wide resection for an osteosarcoma and reconstruction of the proximal left tibia with a rotating hinged knee megaprosthesis. Open biopsy of the distal leg mass showed necrobiotic tissue, metallosis, fibroblasts, osteoblasts, histiocytes, and multinucleated giant cells. The patient underwent debridement of the distal leg mass, metallosis, and wear debris surrounding the tibial component, followed by revision of the destructed polyethylene-bearing components. At the latest follow-up, 4 years after the revision surgery, the patient is alive and tumor-free, asymptomatic, and has no clinical or imaging evidence of wear and metallosis.