Progressive Loosening in Metal-on-Metal Total Hip Arthroplasty after Fifteen Years of Effective Function: Two Case...

Metallosis is a pathological condition associated with the release of metal debris from joint implants, particularly metal-on-metal (MoM) articulations in total hip arthroplasty (THA). The metal debris triggers adverse local tissue reactions, including aseptic lymphocyte-vasculitis-associated lesions (ALVALs), pseudotumor formation, and progressive implant loosening.

Case 1 - A 64-year-old male presented with hip pain and limping 15 years after an uncemented MoM THA. Investigations revealed femoral stem loosening. Intraoperatively, dark synovial fluid, necrotic tissue, elevated cobalt, and chromium levels were consistent with metallosis were identified. Revision surgery replaced the components with alternative bearings, and the patient returned to normal activities within a year. Case 2 - A 63-year-old female with bilateral MoM THAs reported similar symptoms 15-year post-surgery. Imaging identified a pseudotumor and femoral loosening. Elevated serum metal ion levels confirmed the diagnosis. Revision surgery revealed ALVAL, and components were replaced with ceramic-on-polyethylene implants, resolving symptoms.

Metallosis poses a significant risk in MoM THA, caused by wear and corrosion, leading to systemic and local tissue damage. Timely diagnosis through clinical evaluation, imaging, and serum metal ion levels is critical for intervention. Revision surgeries are effective in managing metallosis and restoring function. These cases highlight the importance of long-term monitoring and the consideration of alternative bearing surfaces in hip arthroplasty.