Abstract
The adverse biological impact of orthopaedic wear debris currently limits the long-term safety of human joint replacement devices. We investigated the role of particle size, surface composition and donor variation in influencing the biological impact of silicon nitride as a bioceramic for orthopaedic applications. Silicon nitride particles were compared to the other commonly used orthopaedic biomaterials (e.g. cobalt-chromium and Ti-6Al-4V alloys). A novel biological evaluation platform was developed to simultaneously evaluate cytotoxicity, inflammatory cytokine release, oxidative stress, and genotoxicity potential of particles using peripheral blood mononuclear cells (PBMNCs) from individual human donors. Irrespective of the particle size, silicon nitride did not cause any adverse responses whereas cobalt-chromium wear particles caused donor-dependent cytotoxicity, TNF-α cytokine release, oxidative stress, and DNA damage in PBMNCs after 24 h. Despite being similar in size and morphology, silicon dioxide nanoparticles caused the release of significantly higher levels of TNF-α compared to silicon nitride nanoparticles, suggesting that surface composition influences the inflammatory response in PBMNCs. Ti-6Al-4V wear particles also released significantly elevated levels of TNF-α cytokine in one of the donors. This study demonstrated that silicon nitride is an attractive orthopaedic biomaterial due to its minimal biological impact on human PBMNCs.
Highlights
The adverse biological impact of orthopaedic wear debris currently limits the long-term safety of human joint replacement devices
CoCr particles showed the presence of oxygen in addition to cobalt, chromium, molybdenum and other trace elements, which suggested the presence of chromium oxide (Cr2O3)
New generation orthopaedic biomaterials such as Si3N4 need to be thoroughly investigated for their potential to induce adverse responses in humans
Summary
The adverse biological impact of orthopaedic wear debris currently limits the long-term safety of human joint replacement devices. This study demonstrated that silicon nitride is an attractive orthopaedic biomaterial due to its minimal biological impact on human PBMNCs. Silicon nitride is an industrial ceramic used for high-performance applications such as heat exchangers, gas turbines, and automotive engines due to its excellent temperature resistance, superior mechanical strength, relatively high toughness, and abrasion resistance[1]. Monolithic Si3N4 and ceramic-like silicon nitride coatings are actively being investigated as potential bearing materials for orthopaedic reconstruction devices such as total hip replacements[6,7]. It is increasingly evident from recent studies that Si3N4 surface chemistry plays an important role in its biological identity and interaction with cells[4,8]. Any new orthopaedic biomaterial such as Si3N4 requires thorough testing to determine if its particulates potentially induce adverse responses in humans
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