Over 300,000 total knee replacement procedures are performed in the United States alone, and their performance is limited by wear. Coatings of ceramics are known to decrease wear of the ultra-high molecular weight polyethylene (UHMWPE) component of orthopedic joint replacements. Polyethylene wear debris is known to cause osteolysis which is a key factor in loosening of the prosthesis, leading to the need for a revision procedure. An alumina-zirconia composite is proposed as a new material to serve as the ceramic coating. With the hardness of alumina and the toughening effects of zirconia, the coating promises to be superior to either material alone. Both materials are biocompatible. The films will be coated by metalo-organic chemical vapor deposition (MOCVD), a method which is characterized by high growth rates and excellent surface conformality. Films will be coated at reduced and at atmospheric pressure onto CoCr surfaces which have been preconditioned with a thin ion-implanted layer of alumina. The important properties of film adhesion, composition, and hardness will be tested and analyzed.
This proposal addresses a process for increasing the lifetime of orthopedic devices in a manner which is nearly of equivalent cost compared to conventional ion implantation, which is presently being employed. ISC has production facilities for such implantation treatment having nitrogen ion implanted over 30,000 units to date. The proposed coating may represent at least one of the next generation solutions to the problem of enhanced service lifetime.
| Ylostalo, Joni; Smith, Jason R; Pochampally, Radhika R et al. (2006) Use of differentiating adult stem cells (marrow stromal cells) to identify new downstream target genes for transcription factors. Stem Cells 24:642-52 |
