Testing of silicon nitride ceramic bearings for total hip arthroplasty
ABSTRACT Modern ceramic bearings used in total hip arthroplasty (THA) consist of a femoral head (ball) articulating inside a hemispherical acetabular cup (socket); the ball and socket are made of alumina (Al(2)O(3)) and Al(2)O(3)-based composite materials. In the present study, total hip bearings were made from a different ceramic material, silicon nitride (Si(3)N(4)), by sintering and hot isostatic pressing of powders. The resulting material had improved mechanical properties over modern Al(2)O(3) THA bearings, with a flexural strength of 920 +/- 70 MPa, a Weibull modulus of 19, and a fracture toughness of 10 +/- 1 MPa m(1/2). Unlike zirconia-based ceramics that have also been used in THA, accelerated aging of Si(3)N(4) did not adversely affect the flexural strength. In simulated wear tests, Si(3)N(4) acetabular cups produced low-volumetric wear whether articulating against Si(3)N(4) or cobalt-chromium (CoCr) femoral heads. The results of this investigation suggest that Si(3)N(4) may allow improved THA bearings that combine the reliability of metal femoral heads with the low wear advantages of ceramic materials.
Tribology International 09/2015; 89:72-77. DOI:10.1016/j.triboint.2014.12.008 · 1.94 Impact Factor
- "To deal with this problem, zirconia-toughened alumina (ZTA) composites are the most recent solution available in the market (Biolox-Delta from Ceramtec), bearing with improved fracture toughness decreasing the ceramic fracture rate and wear . Another well-known ceramic material for structural applications is silicon nitride (Si 3 N 4 ), which presents a marked fracture toughness value of 10 MPa m 1/2  higher than 6.5 MPa m 1/2 from ZTA . Indeed, Si 3 N 4 ceramics were far-seeing proposed by Zhou et al.  as a structural material for articular implants, and in the last decade by others [7,10–17]. "
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- "Today, silicon nitride is used for spinal implants and in early 2011 the first silicon nitride femoral head was implanted in USA. The choice of silicon nitride as an implant material is motivated by its excellent biocompatibility, low wear rates as well as relatively high fracture toughness and strength (Mazzocchi and Bellosi, 2008; Mazzocchi et al., 2008; Sonny Bal et al., 2008, 2009). "
ABSTRACT: Total joint replacements currently have relatively high success rates at 10-15 years; however, increasing ageing and an active population places higher demands on the longevity of the implants. A wear resistant configuration with wear particles that resorb in vivo can potentially increase the lifetime of an implant. In this study, silicon nitride (SixNy) and silicon carbon nitride (SixCyNz) coatings were produced for this purpose using reactive high power impulse magnetron sputtering (HiPIMS). The coatings are intended for hard bearing surfaces on implants. Hardness and elastic modulus of the coatings were evaluated by nanoindentation, cohesive, and adhesive properties were assessed by micro-scratching and the tribological performance was investigated in a ball-on-disc setup run in a serum solution. The majority of the SixNy coatings showed a hardness close to that of sintered silicon nitride (∼18GPa), and an elastic modulus close to that of cobalt chromium (∼200GPa). Furthermore, all except one of the SixNy coatings offered a wear resistance similar to that of bulk silicon nitride and significantly higher than that of cobalt chromium. In contrast, the SixCyNz coatings did not show as high level of wear resistance.05/2013; 25. DOI:10.1016/j.jmbbm.2013.05.002
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ABSTRACT: Improvements in prosthetic materials, designs, and implant fixation for THA have led to bearing surface wear being the limitation of this technology. Hard-on-hard bearings promise decreased wear rates and increased survival. However, there may be different survival rates based on bearing materials, manufacturing technologies, and femoral component designs. Additionally, survival rate variability may be based on study design. We determined survival rates and study levels of evidence and quality for the following bearings: stemmed metal-on-metal THA, metal-on-metal hip resurfacing, ceramic-on-ceramic THA, and ceramic-on-metal THA. We performed a systematic review of the peer-reviewed literature addressing THA hard-on-hard bearings. Quality for Level I and II studies was assessed. The four Level I or II second-generation stemmed metal-on-metal THA studies reported between 96% and 100% mean survival at 38 to 60 months. The two Level I hip resurfacing studies reported 94% and 98% mean survival at 56 and 33 months. The four Level I studies of ceramic-on-ceramic THA reported survival from 100% at mean 51 months to 96% at 8 years. While hard-on-hard bearing survival rates have generally been variable with earlier designs, contemporary implants have demonstrated survival of 95% or greater at followup of between 3 and 10 years. Some variability in survival may be due to differences in surgical technique, component positioning, and implant designs. As bearing designs continue to improve with modified materials and manufacturing techniques, use will increase, especially in young and active patients, though concerns remain about the increased reports of adverse events after metal-on-metal bearings.Clinical Orthopaedics and Related Research 11/2010; 469(6):1536-46. DOI:10.1007/s11999-010-1658-0 · 2.77 Impact Factor