Severe Metallosis after Tumor Mega-Prosthesis: Revise or Retain? - A Case Series.

INTRODUCTION

Tumor mega-prostheses are widely used for limb salvage following resection of bone tumors. Although infection and aseptic loosening are the most common causes of failure, metallosis secondary to structural failure is uncommon and may mimic other complications. We describe a case series of two cases of severe metallosis following tumor mega-prosthesis reconstruction.

CASE REPORT: The first case involved a 34-year-old man who presented with valgus deformity, pain, and restricted knee motion 3 years after proximal tibial reconstruction for a giant cell tumor. Inflammatory markers were normal, and radiographs showed no loosening or implant breakage. Surgical exploration revealed extensive metallosis caused by polyethylene bushing failure of the hinge mechanism. Radical debridement and isolated bushing exchange restored alignment and function while preserving well-fixed components. A second case involved a 24-year-old man with pain in the leg 2 years after distal tibial replacement for osteosarcoma. Radiographs demonstrated osteolysis and stem loosening. However, markers of inflammation were within normal limits. This scenario raised concerns of possible infection or a structural failure. Intraoperatively, severe metallosis with implant loosening was identified. Extensive debridement and revision reconstruction with a longer cemented stem were performed.

CONCLUSION

Metallosis is a rare but potentially devastating complication of tumor mega-prostheses reconstruction. Polyethylene bushing failure and implant loosening can result in metal-on-metal articulation and extensive tissue damage. Early recognition, exclusion of infection, and timely surgical intervention may permit limited revision and prevent catastrophic implant failure.