A Case of Catastrophic Failure of Tibial Component with Extensive Metallosis Following Total Knee Arthroplasty: A Case Report.

INTRODUCTION: Total knee arthroplasty (TKA) is commonly performed for severe knee disorders, but complications such as metallosis, though rare, can arise and lead to significant morbidity. Extensive metallosis following TKA is not well documented in the literature, and this report adds to the limited existing data on its clinical presentation and management. CASE REPORT: A 72-year-old woman who had undergone bilateral primary TKA in 2008 developed extensive metallosis after a twisting injury to the right knee in 2021, resulting in pain, swelling, and a progressive varus deformity. In September 2023, following a fall, she experienced acute pain and was found to have loosening of the prosthesis secondary to metallosis. Radiographs showed a loose tibial component with significant wear, and the "cloud and bubble sign" characteristic of metal-induced synovitis. After infection was excluded, a one-stage revision was performed using a cemented semi-constrained modular knee system. Surgery revealed severe synovial staining, metal debris, and extensive wear of the tibial base plate; the components were removed and the joint reconstructed with a constrained condylar prosthesis. CONCLUSION: Postoperatively, the patient recovered well, achieving full weight-bearing and a range of motion from 0° to 100°. At 1-year follow-up, she remained symptom-free with no evidence of implant loosening or osteolysis. This case underscores the importance of long-term surveillance and early detection of metallosis in TKA patients so that revision can be undertaken before extensive bone loss occurs.