Orthopaedic operations
Ashley W. Blom, David Warwick, Michael R. Whitehouse in Apley and Solomon’s System of Orthopaedics and Trauma, 2017
Corrosion is inevitable unless the implanted metal is treated, for example by passivation, which creates a protective passive layer; this is usually an oxide layer formed from chemical treatment. In stainless steel and cobalt–chromium, it is the chromium component that helps in creating an oxide layer; in titanium, the element itself forms it. With passivated metal alloys used in orthopaedic surgery, corrosion is rarely a problem except when damage to the passive layer occurs; it may be initiated by abrasive damage or minute surface cracks due to fatigue failure. Even in the absence of these faults, failure can occur through crevice corrosion (where the process is heightened by low oxygen concentrations in crevices, e.g. beneath the heads of screws and plates) or stress corrosion (where repeated low stresses in a corrosive environment cause failure before the fatigue life of the implant is reached). The products of corrosion, metal ions and debris, cause a local inflammatory response that accelerates loosening. Recently there has been a renewed interest in wear of the trunnion (the join of the neck and modular head) in hip arthroplasty.
Environmental toxicants on Leydig cell function
C. Yan Cheng in Spermatogenesis, 2018
Chromium is a heavy metal that is commonly used in industrial processes such as leather tanning operations, metal processing, stainless steel welding, chromate production, and chrome pigment production. When chromium was exposed, it also strongly accumulated in the interstitial cells in rat testis.231 Chromium may also be a Leydig cell toxicant. Exposure to hexavalent chromium (20, 40, and 60 mg/kg BW/day) for 90 days reduced Leydig cell numbers, downregulated Hsd3b1, and decreased testosterone levels.240 In vitro treatment of chromium to TM3 Leydig cells inhibited steroid production in these Leydig cells.241,242
Heavy Metals
Dongyou Liu in Handbook of Foodborne Diseases, 2018
Chromium is released through the burning of oil and coal and is used in pigment oxidants, catalysts, chromium steel, fertilizers, oil well drilling, and metal plating tanneries. It typically has two forms in the environment: trivalent chromium Cr(III) (which is generally harmless due to its weak membrane permeability) and hexavalent chromium Cr(VI) (which can easily pass through the cell membrane and bind, via thiol groups [–SH], to enzymes responsible for controlling the speed of metabolic reactions) [8].
The role of eugenol in the prevention of chromium-induced acute kidney injury in male albino rats
Published in Alexandria Journal of Medicine, 2018
Chromium (Cr) is a heavy metal that has several valence states; the most common one is the hexavalent chromium (CrVI), that is widely used in industries, e.g. leather tanning, stainless steel manufacturing, chrome plating (chromates added as anticorrosive agents to paints, primers, and other surface coatings), welding and wood preservation.1,2 CrVI can also be found in drinking water and in public water systems.3 Environmental and/or occupational exposure to CrVI-containing compounds is known to be toxic and carcinogenic to human beings and animals.4 A major adverse effect of chromium poisoning is nephrotoxicity due to chromium excretion through the kidney, this increases its chromium content and subsequently, nephropathy occurs.5 The toxic manifestations of chromium are considered to be due to oxidative stress.6,7 leading to serious damage to the vital organs.8,9
The era of biofunctional biomaterials in orthopedics: what does the future hold?
Published in Expert Review of Medical Devices, 2018
Mubashar Rehman, Asadullah Madni, Thomas J. Webster
Although still used today in some parts of the world, metal-on-metal (meaning the hip stem and acetabular cup are composed of metal) orthopedic prostheses, if improperly designed, may result in the generation of metal particles and excessive wear. The first implanted orthopedic device consisted of a femoral head prosthesis and a polymer head which was anchored in the femur by a stainless steel stem. The metallic stem was made according to the shape and size of the femur to distribute weight of the body over a large surface area of bone [23]. This reduced loosening of the prosthesis during weight bearing activities and prevented total prosthesis failure. Cobalt-chromium (Co-Cr) alloys were introduced as orthopedic devices due to mechanical properties similar to stainless steel but with much higher corrosion resistance and a longer fatigue life. These alloys contain Cr 27–30%, Mo 5–7%, and Ni 2.5%. High chromium content in these alloys provides excellent corrosion resistance in biological media even in the presence of high chloride ions [24]. High Ni (33–37%) Co-Cr alloys are widely used in high weight bearing applications. Cast Co-Cr alloys are mainly used for low-weight-bearing applications such as dentistry whereas wrought Co-Cr alloys have been used for high-weight-bearing orthopedic applications, such as stems of hip and knee joints [25]. Of course, as any patient who has a Co-Cr orthopedic implant will tell you, they are quite heavy, much heavier than bone which can provide significant bone bonding issues.
Mechanical properties and performances of contemporary drug-eluting stent: focus on the metallic backbone
Published in Expert Review of Medical Devices, 2019
Ply Chichareon, Yuki Katagiri, Taku Asano, Kuniaki Takahashi, Norihiro Kogame, Rodrigo Modolo, Erhan Tenekecioglu, Chun-Chin Chang, Mariusz Tomaniak, Neville Kukreja, Joanna J. Wykrzykowska, Jan J. Piek, Patrick W. Serruys, Yoshinobu Onuma
Compared with stainless steel, cobalt chromium alloys have higher elastic modulus and tensile strength resulting in a better radial strength and the ability to have thinner struts (Table 1). One bench study demonstrated the improvement of mechanical performance of the cobalt-chromium DES when compared with stainless steel DES [36]. Other than better mechanical properties, the cobalt chromium alloys are more radiopaque and their fluoroscopic visibility is better than stainless steel due to its higher density. Another advantage of this alloys is its low ferromagnetic nature which makes this alloys safe for MRI. Although artifacts on MRI signal was lower in cobalt alloys, platinum and nitinol than stainless steel [37], in vitro and in vivo studies demonstrated no substantial heating or motion of coronary stents in the magnetic field [38,39]. The cobalt chromium alloys commonly used in the manufacturer of coronary stents are L605, cobalt-nickel-chromium alloy (MP35N), and Phynox/Elgiloy. Among these three kinds of alloys, L605 is commonly used due to its highest density and elastic modulus. Current DES using cobalt-chromium alloys as a stent platform are listed in Table 2.
Related Knowledge Centers
- Alloy
- Chromium
- Corrosion
- Iron
- Surgical Instrument
- Nickel
- Carbon
- Self-Healing Material
- Chemical Plant
- Cleanability