The rate of hip replacement has increased to 21% in the last five years. The proportion of hip or knee replacement procedures that needed revision remained in between 16% and 17%. The cemented total hip replacement is normally preferred but cemented implants have only 10-12 years of life span. The osteolysis caused by the fragments of the cement and corrosion in the implants are main reason of the failure of the prosthesis. A number of studies have revealed better biocompatibility and effectiveness of hydroxyapatite-coated implants. The use of poor quality of starting material and the high temperature attained during the plasma-sprayed coatings are the major source of impurities in the hydroxyapatite-coated implants. This leads to weaker bond strength of the coatings, delamination of the coatings and initiation of the corrosion. Since, bone contains nanometer-size carbonated hydroxyapatite crystal (dahllite), it is more logical to use """"""""carbonated hydroxyapatite"""""""" as a coating material for the orthopedic and dental implants. Most of the research efforts were devoted towards nanoparticles of hydroxyapatite-coated implants. The nanoparticle of carbonated hydroxyapatite-coated implants is not investigated comprehensively. ? ? This Phase I research is based on the synthesis of unagglomerated nanoparticles of the carbonated hydroxyapatite as well as coating of Ti-alloy with nanoparticles of carbonated hydroxyapatite at the room temperature. The proposed feasibility study will increase the bond strength of coating, reduce corrosion and subsequently increase the lifespan of the prosthesis. The commercial impact of the above research will be very significant to the US economy. It will minimize the pain and suffering of the patients. The federal government and the insurance industries will benefit in Billion of dollars from the reduced rate of revision of the prosthesis, reduction in the consumption of analgesics and the lost wages. The potential market size of the orthopedic implants is $8 Billion/year by 2007. ? ?
