Bi-coat
Cementless Coating Technology
A double layer coating of pure titanium overlaid with hydroxyapatite (HA), Bi-coat is designed to optimise the surface performance characteristics of the implant, whilst maintaining the mechanical properties of the underlying substrate.
Titanium is widely known to be ‘bone friendly’ and provides greater biocompatibility compared to cobalt chrome(1), increasing the surface roughness of the implant whilst allowing an increased bone interlock. In addition, the HA layer provides a biocompatible surface due to its similarity in composition to the inorganic component of bone, serving as a scaffolding onto which bone cells can attach, migrate, grow and divide, allowing for enhanced bone in-growth. HA has also been shown to be more resistant to wear particle migration and can therefore help to reduce osteolysis around implants(2).
Properties
Each layer of the Bi-coating has a thickness of approximately 100µm and achieves an adhesion strength of >22MPa. The combined coating is designed to aid both primary and secondary fixation. Histology studies(3) have shown that the addition of Bi-coat can increase bone growth at the implant interface, with titanium being more conducive to bone growth in the vicinity of the interface than cobalt chrome, and HA promoting more rapid normalisation of bone at the implant interface.
Both the titanium and the HA coating layers are produced using a highly sophisticated, controlled plasma spray technique. In summary, a high temperature plasma stream is created within the spray gun and the heated plasma issues from the front of the nozzle at high velocity. The coating material is fed into the flame in powder form. The powder is heated and accelerated towards the implant where it impacts, forming a coating layer on the surface.
References:
1. Brunette DM, Tengvall P, Textor M, Thomsen P. Titanium in Medicine: Materials Science, Surface Science, Engineering, Biological Responses and Medical Applications. Springer, 2001.
2. Coathup MJ, Blackburn J, Goodship AE, Cunningham JL, Smith T, Blunn GW. Role of hydroxyapatite coating in resisting wear particle migration and osteolysis around acetabular components. Biomaterials 26(19):4161, 2005.
3. C.G. Collier. The assessment of early osteointegration, as a function of coating. August 2002. Report held on file.
Important: Not all products are available or cleared for distribution in all international markets. For more details, please contact your local subsidiary or distributor by visiting the Corin worldwide section.
