BIOLOY
TiNbN PVD Coating
A TiNbN coating is a ceramic coating applied with the PVD (Physical Vapor Deposition) technique onto a metal substrate, typically cobalt, titanium or steel alloys.
The TiNbN coating, denominated “BIOLOY®“ by Permedica, is utilized to coat prosthetic knee system and some hip and shoulder system metal components manufactured by Permedica.
COATING FUNCTIONS
It is well known that metal materials, except for noble ones, undergo a process of corrosion when inside a biological organism and therefore, release metal ions. Many heavy metals can induce a hypersensitive reaction. Metals noted as potential allergenics are beryllium, nickel, cobalt, chrome and, occasionally tantalum titanium and vanadium. Nickel is the most common allergen of these metals, followed by cobalt and chrome.
Metal ions, even though they themselves are not allergens, can activate the immune system creating complexes with the proteins already present in the organism. These protein complexes are potential allergens responsible for later provoking hypersensitive responses; cell-mediated immunity. Allergenic phenomenon in patients with implanted metal devices is growing as well as awareness of the orthopedic community towards this problem. The need for a type of anti-allergenic prostheses is therefore continually increasing.
BIOLOY® coating has the objective of creating an inert layer and barrier[1,2] that acts as an interface between the patient (in reality between the tissues and liquids) and the metal of the prosthesis, consequently impeding the passage of metal ions from the prosthesis to the patient. The principle function is in fact, to create a physical barrier between the metal substrate and the surrounding organic environment impeding the release of metal ions from the substrate: thus permitting a notable reduction of the risk of provoking a hypersensitivity risk or to develop an allergic reaction caused by metal elements from device alloys (i.e. Ni, Co, Cr).
BIOLOY® coating therefore allows the:
1. Possibility of implanting metal prosthetic devices in patients who have noted allergies to one or more metals of which the devices are manufactured;
2. Reduction of the risk of developing an allergic reaction in a patient in which one or more metallic devices is implanted.
A BIOLOY® coating, moreover, thanks to the elevated hardness and resistance to abrasion, improves the tribological performance of the metal alloy’s joint surface thereby reducing polyethylene wear.
TECHNOLOGY
Physical Vapor Deposition (PVD) is a common method for the atomic deposition under vacuum of thin layers (microns).
The deposition of this film over the substrate (device to be coated) comes at an atomic or molecular level through an atom by atom creation of the film. The layer results can vary from mono-crystal to amorphous, more or less compact, pure or impure, thin or thick.
Physical Vapor Deposition (PVD) is an atomic deposition process where the coating material is evaporated from a solid or liquid source in atomic or molecular form and transferred under vacuum conditions onto a substrate surface where it condenses. In this type of process, the composition is formed through a chemical reaction that takes place between the vaporized material and the gas inside the chamber, i.e. by nitrogen gas in case of nitride coatings or oxygen gas in case of oxide coatings.
The Permedica BIOLOY® coating exploits PVD coating technology with an in vacuum cathodic arc method of evaporation to create an extremely hard, thin and adherent coating of TiNbN (titanium nitride and niobium) over the metal substrate, typically titanium, cobalt and steel alloys.
The BIOLOY® coating process is entirely carried out by Permedica.
[1] Ragone, V., Canciani, E., Biffi, C.A. et al. CoCrMo alloys ions release behavior by TiNbN coating: an in vitro study. Biomed Microdevices 21, 61 (2019).
[2] Bidossi A, Bottagisio M, De Grandi R, De Vecchi E. Ability of adhesion and biofilm formation of pathogens of periprosthetic joint infections on titanium-niobium nitride (TiNbN) ceramic coatings. J Orthop Surg Res. 2020;15(1):90.
TECHNICAL CHARACTERISTICS
The TiNbN coating is a single layer surface coating that esthetically gives a gold color to the surface that is coated.
IThe requirements that must satisfy a BIOLOY® coating are a coating hardness of >2000 HV (Vickers), a thickness of 3÷6 µm and an adhesion characterized by no coating delamination.
