1. Characterization of micro-threaded stem taper surface of cementless hip endoprosthesesDrago Dolinar, Boštjan Kocjančič, Klemen Avsec, Barbara Šetina, Aleksandra Kocijan, Matjaž Godec, Marko Sedlaček, Mojca Debeljak, John T. Grant, Timon Zupanc, Monika Jenko, 2024, original scientific article Abstract: We investigated micro-threaded stem taper surface and its impact on premature failures, aseptic loosening, and infection in cementless hip endoprostheses. Our study focused on the fretting, and crevice corrosion of micro-threaded tapers, as well as the characterization of the microstructure and surface properties of two new and three retrieved Zweymüller stem tapers. The retrieved samples were selected and examined based on the head–stem taper interface being the sole source of modularity with a metallic component, specifically between the Ti alloy taper stem and the ceramic head. To determine the surface chemistry and microstructures of both new and retrieved hip endoprostheses stem taper titanium alloy, scanning -electron microscopy (SEM) was employed for morphological and microstructural analyses. Energy dispersive spectroscopy (EDS) was utilized for characterizing chemical element distribution, and electron backscattered diffraction (EBSD) was used for phase analysis. The roughness of the micro-threated stem tapers from different manufacturers was investigated using an optical profilometer, with standard roughness parameters Ra (average surface roughness) and Rz (mean peak to valley height of the roughness profile) being measured. Electrochemical studies revealed no fretting corrosion in retrieved stem tapers with ceramic heads. Consequently, three retrieved tapers and two new ones for comparison underwent potentiodynamic measurements in Hank’s solution to determine the corrosion rate of new and retrieved stem taper surfaces. The results showed a low corrosion rate for both new and prematurely failed retrieved samples due to aseptic loosening. However, the corrosion rate was higher in infected and low-grade infected tapers. In conclusion, our study suggests that using ceramic heads reduces taper corrosion and subsequently decreases the incidence of premature failures in total hip arthroplasty. Keywords: total hip arthroplasty, stem micro-threaded taper, taper surface morphology, microstructure, corrosion, Ti implant alloy Published in DiRROS: 06.06.2024; Views: 211; Downloads: 208
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2. Sliding wear behaviour of conventional and cryotreated PM Cr-V (Vanadis 6) ledeburitic tool steelVenu Yarasu, Peter Jurči, Peter Gogola, Bojan Podgornik, Marko Sedlaček, 2023, original scientific article Keywords: cold work tool steel, conventional treatment, cryogenic treatment, hardness, reciprocal sliding, wear Published in DiRROS: 08.04.2024; Views: 378; Downloads: 50
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3. Influence of precipitation hardening on the mechanical properties of Co-Cr-Mo and Co-Cr-W-Mo dental alloysMarko Sedlaček, Katja Zupančič, Barbara Šetina, Borut Kosec, Matija Zorc, Aleš Nagode, 2023, original scientific article Keywords: Co-Cr alloys, microstructure analysis, hardness, wear resistance Published in DiRROS: 01.02.2024; Views: 428; Downloads: 233
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4. Influence of boron and nitrogen on the machinability, polishability and wear of martensitic stainless steelsMarko Sedlaček, Barbara Šetina, Vesna Žepič Bogataj, Jaka Burja, 2023, original scientific article Keywords: martensitic stainless steel, boron, nitrogen, wear, machinability, polishability Published in DiRROS: 01.02.2024; Views: 389; Downloads: 161
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5. High temperature friction and galling properties of nanolayered (Cr,V)N coatings and effect of V contentBojan Podgornik, Marko Sedlaček, Barbara Šetina, Miha Čekada, 2023, original scientific article Keywords: (Cr, V)N coating, galling, high-temperature tribology, hot forming, self-lubrication Published in DiRROS: 26.01.2024; Views: 392; Downloads: 216
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