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Online ISSN 1827-1707
Zarattini G., Bonaspetti G., Imberti S., Pazzaglia U. E.
Clinica Ortopedica, Università degli Studi di Brescia, Brescia
Aim. The most common cause of failure in total hip arthroplasty is the aseptic loosening of femoral and acetabular components due to polyethylene wear and consequent production of particulate wear debris. In this retrospective study we examined the ultra high molecular weight polyethylene (UHMWPE) wear patterns in order to evaluate the biomechanics role in the failure of total hip arthroplasty.
Methods. A specimen of 77 UHMWPE acetabular cups, retrieved at revision of total hip ar-
throplasty was studied by macrostructural and scanning electrone microscope (microstructural) analysis. The following parameters were observed: acetabular cup thickness decrease, topography, and wear patterns. Subsequently, the collected data were correlated with the implant longevity.
Results. Our study showed that the greatest rate of wear was associated with the following wear types: surface deformation and delamination, and the least rate of wear was associ-ated with the following wear types: burnishing, abrasion, scratches, suggesting that the best wear characteristics are expression of a damage determined by joint surface motion and mechanical stresses acting on the prosthesis. The results revealed a direct correlation between the implant longevity and the wear rate. Nonetheless, we emphasized that the least wear rate was associated with 7 of the most longeve prosthesis.
Conclusion. Therefore this might suggest that the successful implant outcome in term of longevity would be ascribable to its well position-ing which is of the utmost importance to reduce the wear process.