Metal-on-metal (MoM) hip bearings were largely abandoned due to which specific complication that is unique to this bearing surface?

• A Osteolysis due to polyethylene particle-induced macrophage activation
• B Catastrophic ceramic fracture causing immediate implant failure
• C Adverse local tissue reactions (ALTR) / pseudotumour formation due to cobalt-chromium ion release and metal hypersensitivity ✓
• D Early aseptic loosening due to inadequate osseointegration of the metal femoral head

Explanation

Metal-on-metal bearings generate cobalt and chromium micro- and nanoparticles and ions that cause adverse local tissue reactions (ALTR), also called pseudotumours — masses of necrotic soft tissue and fibrous tissue surrounding the hip. These were particularly common with large-head MoM and hip resurfacing arthroplasties (e.g. DePuy ASR, Zimmer Durom). Elevated serum cobalt and chromium levels are biomarkers. ALTR causes soft-tissue destruction, pain, and implant failure requiring revision. Osteolysis is the characteristic failure mode of older polyethylene bearings. Ceramic fracture is a rare but specific complication of ceramic bearings.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.