Polyethylene Wear Against Alumina and Zirconia Heads in K-Max Total Hip Arthroplasty

Abstract

Polyethylene wears of 22.225 mm diameter alumina and zirconia femoral heads in cemented total hip arthroplasty (THA) were compared at mean follow-up of five years. Ninety-six primary cemented K-MAX THA in eighty-seven patients were observed, forty-six hips with alumina heads and fifty-one hips with zirconia heads. Both of the mean linear wear rate and the mean volumetric wear rate of the polyethylene against zirconia were significantly higher that those of alumina (p<0.01, p<0.01, respectively). The monoclinic phase content and roughness rose up on the surfaces of two retrieved zirconia heads from revision surgeries. This was supposed as the differences of thermal conductivity between alumina and zirconia, for which local temperature was higher in zirconia head, leading to the phase transformation and lower-temperature aging degeneration (LTAD) of zirconia head surface.