A 58-year-old active male is counselled regarding bearing surface options for his planned total hip replacement. He is concerned about implant longevity given his age and activity level. Which bearing couple has the lowest volumetric wear rate in laboratory studies?

• A Metal-on-conventional polyethylene (CoP)
• B Metal-on-metal (MoM)
• C Ceramic-on-highly cross-linked polyethylene (CoXLPE)
• D Ceramic-on-ceramic (CoC) ✓

Explanation

Ceramic-on-ceramic (CoC) bearings produce the lowest volumetric wear of all current bearing couples in laboratory studies, due to extremely high hardness and exceptional wettability of alumina or alumina matrix composite ceramics. However, CoC carries a small risk of squeaking and catastrophic fracture. Metal-on-metal was thought to have low wear by volume but generates nanometer-sized cobalt-chrome ions causing local adverse reactions (ARMD/ALVAL), leading to its decline. Ceramic-on-XLPE has very low wear and no ion concerns. Conventional polyethylene produces the highest wear debris.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.