Biocompatibility of titanium and titanium alloys
Unalloyed and alloyed titanium have been used in medical engineering for many years. The applications are varied and include the following:
- joint replacement parts for hip, knee, shoulder, spine, elbow and wrist,
- bone fixation materials such as nails, screws, nuts and plates,
- dental implants and parts for orthodontic surgery and dental prosthetics,
- heart pacemaker housings and artificial heart valves,
- surgical instruments for heart and eye surgery,
- components in high-speed blood centrifuges.
No general answer can be given to the question of which titanium alloy is best for implants and surgical instruments. This applies both according to the generally held opinion that the biocompatibility of an alloy is determined solely by its corrosion resistance and the toxicity of its corrosion products and according to the opinion that tissue compatibility requires high resistance of the surface layers. Materials to be used as permanent implants in the human body must be, among other things, biocompatible, corrosion-resistant, tissue compatible, vital and elastic. The titanium materials meet these requirements to a very high degree.
Reservations have been expressed about the presence in long-term implants of elements such as vanadium which are toxic in the elemental state. These concerns have led to the development of special titanium implant alloys such as TiAl5Fe2,5 (TIKRUTAN LT 35) and TiAl6Nb7. In addition, increased use of beta titanium alloys as implant materials has been observed in recent years.
The question of the biocompatibility of titanium materials has been widely discussed and various studies have been carried out. The steadily increasing importance of titanium-base materials as implant materials has been referred to repeatedly at many specialist conferences.
We refer you in this connection to the relevant publications.
Deutsche Titan, Nov. 2000