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Orthopaedic Proceedings

Vol. 98-B, Issue SUPP_3 | Pages 125 - 125

1 Jan 2016

TETRAGONAL ZIRCONIA STABILISATION IN ZPTA CERAMIC FOR ARTHROPLASTY

Porporati AA Leto A Kuntz M Streicher R

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INTRODUCTION

Ceramics are excellently suited for applications in arthroplasty, mainly total hip, knee and shoulder replacement. As the most prominent representative of this demanding type of material, BIOLOX^®delta is widely used and very successful in the market for more than 10 years. The ability of zirconia phase transformation (t-ZrO₂→m-ZrO₂) in zirconia-platelet toughened alumina (ZPTA) ceramics is an indispensable prerequisite for their excellent mechanical properties. The degree of stabilization of the zirconia tetragonal phase at body temperature is essential for the desired toughening mechanism. Y₂O₃ is the most widely used t-ZrO₂ chemical stabilizer; also microstructure and grain size contribute to t-ZrO₂ phase stabilization. Stabilization must be achieved such that no material degradation will occur in body environment, i.e. in aqueous liquid (synovia), which is known to potentially trigger phase transformation at the surface of ceramic components. In this study, it is shown how phase stabilization in BIOLOX^®delta as a reference material is excellently balanced by means of optimal mechanical performance and environmental stability.

OBJECTIVES

To assess the influence of t-ZrO₂ chemical stabilization on ZPTA properties, in terms of fracture toughness (i.e. the ability to resist crack extension), wear resistance and environmental stability.

Orthopaedic Proceedings

Vol. 98-B, Issue SUPP_3 | Pages 124 - 124

1 Jan 2016

FRETTING AND CORROSION RISK OF CERAMIC BALL HEADS WITH METAL SLEEVES

Porporati AA Pandorf T Flohr M Preuss R Streicher R

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INTRODUCTION

The role and importance of fretting and corrosion in modular hip endoprostheses has become of more and more interest within the last years. Especially bearing couples with large diameters may experience high friction moments leading to an increase of relative micro movements between the surfaces of the taper connections. Recently published studies show that the risk of fretting and corrosion is significantly reduced by using ceramic ball heads compared to metal ball heads.

OBJECTIVES

Goal of this study was to investigate the risk of fretting and corrosion as well as possible loosening of large ceramic ball heads with metal sleeves.

Orthopaedic Proceedings

Vol. 98-B, Issue SUPP_3 | Pages 123 - 123

1 Jan 2016

SURFACE STABILITY OF CERAMIC-CERAMIC BEARINGS ON HIP SIMULATOR WEAR TESTING

Porporati AA Pandorf T Haeussler K Streicher R Preuss R Kaddick C

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INTRODUCTION

The reported revision rate for THA is below 10% at 10 years. Major factors for revision are aseptic loosening or dislocation of the articulating components. CoC bearings in total hip arthroplasty (THA) have demonstrated very low wear rates. Due to producing the least number of wear particles of any articular bearing used for THA, osteolysis is very rarely observed. Zirconia-platelet toughened alumina (ZPTA) has improved toughness and bending strength while maintaining all other advantageous properties of alumina. Consequently, its clinical fracture rate is minimal and wear resistance is superior to alumina.

OBJECTIVES

Since a trend exists towards the usage of larger bearings the aim of this study was to compare the tribological behavior of different ZPTA/ZPTA THAs with respect to their ball head diameter.

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