| Popis: |
After failure of the first metal-on-metal articulations [1,2], there has been a revival since 1988 and nnany studies have reported significant better wear behaviour compared to metal-on-polyethylene bearings [3,4,5]. Based on the experiences of the last decades v/e know that metallic ions are being released in patients with total hip arthroplasty with a metal-on-metal articulation [6J]. The greater part of metallic debris generation is presumed at the articulating surfaces. Other sources of metallic ion release such as corrosion, component impingement or dissociation of ions are reported as well [8]. Modularity and carbon content of the articulating metal-alloy components also seem to play a major role. While low carbide metal articulations are faced with high revision rates up to 9% [9], high carbide metal pairings show better clinical performance [10]. Ceramic-on-ceramic articulations have now a history of more than 30 years in total hip arthroplasty since Boutin implanted the first all ceramic articulation. Due to improper material and unfavourable designs in the 70's and early 80's the mechanical performances of ceramic articulations were not fully satisfactory thus leading to a poor reputation for ceramic as material for total joint arthroplasty [11,12,13]. Nevertheless in the last decades materials and manufacturing processes have improved significantly. Simulator tests confirmed the excellent wear behaviour of ceramics [14]. As the risk of fracture of a ceramic component still exists, it is mandatory that surgeons using this material acknowledge the importance of a precise surgical technique [15,16,17]. To improve the wear characteristics of ultrahigh molecular weight polyethylene (UHMWPE), cross-linked-polyethylene was developed. There are basically three different methods to achieve cross-linking [18]. So far laboratory data present excellent wear behaviour of this new material. Clinical data available include only short term experiences, allowing no conclusion about its effectiveness in the longterm [19]. The aim of this study was to assess and evaluate the blood concentrations of Co, Cr, Mo, Ti, Al and Nb In patients with a well functioning primary total hip arthroplasty. |
