The present evidence indicated the similar performance in survivorship among CoC , CoPc , CoPxl and MoPxl bearing implants , and that all likely have superiority compared with the MoM and MoPc bearing implants in THA procedures .
PURPOSE Although many  total hip bearing implants  are widely used all over the world , simultaneous comparisons across the numerous available bearing surfaces are rare .
The purpose of this study was to compare the survivorship of total hip arthroplasty ( THA ) with six available bearing implants .
The creep and wear of highly cross-linked polyethylene: a three-year randomised, controlled trial using radiostereometric analysis.
The creep and wear behaviour of highly cross-linked polyethylene and st and ard polyethylene liners were examined in a prospect i ve , double-blind r and omised , controlled trial using radiostereometric analysis . We r and omised 54 patients to receive hip replacements with either highly cross-linked polyethylene or st and ard liners  and determined the three-dimensional penetration of the liners over three years . After three years the mean total penetration was 0.35 mm ( SD 0.14 ) for the highly cross-linked polyethylene group and 0.45 mm ( SD 0.19 ) for the st and ard group . The difference was statistically significant ( p = 0.0184 ) . From the pattern of penetration it was possible to discriminate creep from wear . Most ( 95 % ) of the creep occurred within six months of implantation and nearly all within the first year . There was no difference in the mean degree of creep between the two types of polyethylene ( highly cross-linked polyethylene 0.26 mm , SD 0.17 ; st and ard 0.27 mm , SD 0.2 ; p = 0.83 ) . There was , however , a significant difference ( p = 0.012 ) in the mean wear rate ( highly cross-linked polyethylene 0.03 mm/yr , SD 0.06 ; st and ard 0.07 mm/yr , SD 0.05 ) . Creep and wear occurred in significantly different directions ( p = 0.01 ) ; creep was predominantly proximal whereas wear was anterior , proximal and medial . We conclude that penetration in the first six months is creep-dominated , but after one year virtually all penetration is due to wear . Highly cross-linked polyethylene has a 60 % lower rate of wear than st and ard polyethylene and therefore will probably perform better in the long term
The present evidence indicated the similar performance in survivorship among CoC , CoPc , CoPxl and MoPxl bearing implants , and that all likely have superiority compared with the MoM and MoPc bearing implants in THA procedures .
PURPOSE Although many  total hip bearing implants  are widely used all over the world , simultaneous comparisons across the numerous available bearing surfaces are rare .
The purpose of this study was to compare the survivorship of total hip arthroplasty ( THA ) with six available bearing implants .