What is metallosis in hip arthroplasty and when does it prompt revision?

• A. Deposition of metal debris in surrounding tissues causing tissue reaction; can prompt revision
• B. A type of infection
• C. A type of dislocation
• D. A normal sequela of aging

Answer: (A)

Metallosis occurs when metal wear debris from a hip prosthesis deposits into the surrounding soft tissues, triggering a local inflammatory and fibrotic reaction. This reaction can cause pain, soft-tissue discoloration or necrosis, and, importantly, progressive osteolysis or component loosening as the tissue environment is disrupted by metal ions such as cobalt and chromium. Because this tissue response can undermine the stability and function of the implant, a revision is considered when the reaction is clinically significant or progressive—for example, ongoing pain, functional decline, detectable loosening or extensive osteolysis on imaging, or evidence of an adverse local tissue reaction with rising metal ion levels. Metallosis is not an infection, nor is it simply a dislocation or an inevitable part of aging; it represents a debris-induced tissue reaction that may necessitate surgical revision if the damage and symptoms are substantial.