The proposed study aims to evaluate the feasibility of applying Hypersonic Plasma Particle Deposition (HPPD) technique in regional coating Ti6Al4V used in orthopedic implants such that the surface modified region of HPPD coated Ti6Al4V is capable of being the articulating surface while the uncoated region remains ideal for bone and tissue in-growth. This is a novel application since HPPD coating has not previously been used on Ti6Al4V, nor in the orthopedic field. We hypothesize that the application of the HPPD coating process on Ti6Al4V will increase the life expectancy of Ti6Al4V implants while reducing risk of wear particles due to its superior nano-scale film characteristics. The long-term objective is to bring scientific advances in orthopedic implant coatings that will improve health by eliminating or decreasing wear-related replacement surgeries. As the first fundamental step of evaluating the hypothesis, we plan to conduct the following study in Phase I:
Specific Aim 1 : To modify the HPPD process thermal characteristics to make proper molecular bonding for application of TiN, SiC, and Si thin film nanocoating on Ti6Al4V, a substrate material that the HPPD process has not heretofore been adapted for.
Specific Aim 2 : To evaluate wear resistance, along with other tribology characteristics (hardness, modulus, fracture toughness, surface smoothness, composition, thickness, bond strength) of the HPPD coated Ti6Al4V, and compare it to literature and Co-Cr-Mo alloy.
Specific Aim 3 : To assess the in-vitro biocompatibility/cell viability of the HPPD coated Ti6Al4V and compare it with that of Co-Cr-Mo alloy. As a succession of the above evaluation, we plan to examine more aspects in Phase II, including: coefficient of friction;corrosion resistance;fatigue resistance;in vivo biocompatibility on animal model;and wear particle analysis. While all these outlined aspects are necessary to be thoroughly assessed, the wear resistance, and in vitro biocompatibility in Phase I of the study are the prerequisite for the subsequent assessments in Phase ll.
Superior wear resistance and excellent bone in-growth are both essential requirements for orthopedic cement-less implants, yet with the current techniques it is difficult to achieve both in hip resurfacing and small joints such as temporomandibular joint and carpometacarpal joint because of the limited anatomical or prosthetic space. The superior nano-scale film characteristics of our proposed Hypersonic Plasma Particle Deposition (HPPD) coated Ti6Al4V implants are ideal to achieve both goals in the above applications. The overall goal of this project is to examine the wear, hardness, modulus, fracture toughness, surface smoothness, composition, thickness, bond strength, and biocompatibility on Ti6Al4V, as a means to improve health through improved implant quality and longevity.
