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Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_9 | Pages 130 - 130
1 May 2016
THE EFFECT OF CERAMIC FEMORAL HEAD MATERIAL COMPOSITION ON POLYETHYLENE STRUCTURE AND OXIDATION IN TOTAL HIP BEARINGS
Pezzotti G Puppulin L Boffelli M McEntire B Rahaman M Yamamoto K Bal B
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Introduction

In total hip arthroplasty (THA), polyethylene (PE) liner oxidation leads to material degradation and increased wear, with many strategies targeting its delay or prevention. However, the effect of femoral head material composition on PE degradation for ceramic-PE articulation is yet unknown. Therefore, using two different ceramic materials, we compared PE surface alterations occurring during a series of standard ceramic-PE articulation tests.

Materials and Method

Ceramic-PE THA bearings were tested in a simulator, using ASTM F2003-02, ASTM F1714-96 (2013) and ISO 14242:1–3 standards. Acetabular liners (Apex-Link PolyTM, OMNI Life Science, East Taunton, MA, USA) were articulated against Ø28 mm Si3N4 femoral heads (Amedica Corp., Salt Lake City, UT, USA). For comparison, ArCom® PE liners (Biomet Inc. Warsaw, IN, USA) were also tested against Ø28 mm zirconia-toughened alumina (ZTA) femoral heads (BIOLOX®delta, CeramTec GmbH, Plochingen, Germany), under the same conditions. After 5 million cycles of wear, all specimens were examined using nano-spectroscopy tools. Evaluations were performed on six couples per group, plus 3 untested control couples; n= 6 (+3). Spectrographic examinations generated 8 maps of 400 points each randomly selected on the wear zones of each liner, with each map area being 20 µm2 at an in-plane spatial resolution of 1 µm.

Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_7 | Pages 45 - 45
1 May 2016
SURFACE MODULATION OF SILICON NITRIDE CERAMICS FOR ORTHOPAEDIC APPLICATIONS
Bock R McEntire B Bal B Rahaman M Boffelli M Pezzotti G
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Introduction

Silicon nitride (Si3N4) is a ceramic material presently implanted during spine surgery. It has a fortunate combination of material properties such as high strength and fracture toughness, inherent phase stability, scratch resistance, low wear, biocompatibility, hydrophilic behavior, easier radiographic imaging and resistance to bacterial biofilm formation, all of which make it an attractive choice for orthopaedic applications beyond spine surgery. Unlike oxide ceramics, (e.g., alumina or Al2O3) the surface chemistry and topography of Si3N4 can be precisely engineered to address in vivo demands. Si3N4 can be manufactured to have an ultra-smooth, or highly fibrous, or porous morphology. Its chemistry can be varied from that of a silica-like surface composed of silanol moieties to one which is predominately comprised of silicon-amine functional groups.

Methods

In the present study, a Si3N4 bioceramic formulation was exposed to thermal, chemical, and mechanical treatments in order to induce changes in surface composition and features. The treatments included grinding and polishing, etching in hydrofluoric acid solution, and heating in nitrogen or air. Resulting surfaces were characterized using a variety of microscopy techniques to assess morphology. Surface chemical and phase composition were determined using x-ray photoelectron and Raman spectroscopy, respectively. Streaming potential measurements evaluated surface charging, and sessile water drop techniques assessed wetting behavior.