Considerations for the Use of Bearing Partners in Total Hip Arthroplasty

摘要

Nowadays, the major limiting factor of long-term survival of total hip replacements is wear debris generated by the bearing surface (Pospischill and Knahr 2005). The debris induces osteolysis around the implant leading to subsequent aseptic loosening (Harris 2001). Due to this fact, a major effort has been made to improve the original UHMW-polyethylene introduced by Charaley in the 1960s on the one hand and to develop alternative bearing surfaces on the other hand (Santavirta et al. 2003). The surgeon can currently choose between metal-/ceramic-on-polyethylene, metal-/ ceramic-on-cross-linked polyethylene, metal-on-metal, and ceramic-on-ceramic couplings. Despite the significantly reduced wear rate of all the alternative articulations, orthopedic surgeons are still faced with problems related to each single combination (MacDonald 2004; Barrack et al. 2004). Comprehensive knowledge of the characteristics of the articulating materials used by the surgeon is mandatory to avoid unexpected complications. Due to excellent long-time survivorship rates of hip replacements, the average age of a primary THA patient decreased over the last couple of years. Younger, more active patients with increasing demands on their implant are operated. For this young population, increased stability and range of motion with minimal wear of the articulations are required.