FinQ1)There are generally four types of replacement components used in THA which are metal on metal, metal on plastic and ceramic on ceramic, ceramic on plastic. The types of prosthetics used depend on the patient's needs and the surgeon's procedure. All hip replacements have one thing in common: they contain a ball and socket joint. The materials used in the ball and socket, along with the so-called "bearing", like a bearing in a car, can alter the long-term life of the combined replacement. Metal-on-metal hip implants have been used even longer than metal-on-plastic implants. Metal-on-metal bearings (cobalt-chromium alloy, titanium alloy, or sometimes stainless steel) were in use as early as 1955, however the FDA did not authorize their use in the United States until 1999. They propose the possibility for a significantly reduced wear, as well as less inflammation and less bone loss. Small mechanism recalls have drawn negative attention to Metal-on-Metal. Metal-on-metal components allow for larger heads across the full range of implant sizes. Colossal ball heads offer greater gesture range and greater stability, which can significantly reduce the risk of hip dislocation, a critical factor in long-term implant placement. Metal on Plastic Metal on Plastic is the most extensively attempted and tested bearing. The convex femoral stem is made of metal, and the concave cup liner is made of polyethylene plastic. Ceramic on ceramic is a good combination along with longevity and reliability. A high-strength ceramic bearing has been combined in this hip, which ensures extremely low wear performance. Ceramic is the hard...... center of the paper......countless connected elements of the gesture, flexibility and stability of the joint. Works Cited http://www.copper.org/applications/electrical/building/ http://engineering.unt.edu/materials/ http://www.ejbmetals.com/pdf/datasheets-metal_strip/Ca101-102. pdf http://www.uom.ac.mu/faculties/foe/mped /Students_Corner/notes/EnggMaterials/copper.pdf http://info.ornl.gov/sites/publications/files/Pub35345.pdf http:/ /www.sequoia-brass-copper.com/store/alloy-c10100-ofe -copper.html http://en.wikipedia.org/wiki/Oxygen-free_copper http://phys.org/news/2012-01 -metal-alloys-energy-environment-benefit.html photo http://www .orthop.washington.edu/?q=patient-care/articles/what-is-hip-replacement-a-review-of-total- hip-arthroplasty.html http://bonesmart.org/hip/hip-replacement -implant-materials/ENGINEERING MATERIALS Mrs. Shetha Daniel Caledonian College of Engineering, Sultanate of Oman