Novel wear resistant coatings with gradient interfaces for long lasting hip prostheses

PROJECT SUMMARY The broader impact of this Small Business Innovation Research Phase I project is to improve the clinical success and longevity of orthopedic prostheses for younger and active Americans to get relief from debilitating pain and to improve the quality of their life. The long-term survival of total hip replacements (THR) in young, active patients with higher demands remains a challenge for orthopedic surgeons. From 2000 to 2010, while THR procedures rose by 92% in people age 75 and older, they increased by 205% in young people ages 45 to 54. Patients aged 50 years or younger with artificial hips are at high risk for wear-related complications and mechanical failure mostly due to hip dislocation due to their higher levels of activity. Currently, Biolox Delta and Oxinium™ femoral heads are commonly used for THRs for the increasing population of young, active patients. Biolox Delta heads have shown remarkable wear performance and low fracture rate in the mid-term follow-ups. However, their long term in vivo stability is a concern due to surface instability of zirconia content. Several clinical cases of damaged Oxinium™ heads after hip dislocation have raised concerns about their durability. The focus of this project is to develop a new kind of artificial hip joint, made of hard ceramic coatings on tough Ti alloy femoral heads, with high durability to damage by hip dislocation. Our innovation expands scientific and technical understanding of such ceramic coatings by investigating methodologies that form diffusion-bonded ceramic coatings on the Ti-6Al-4V alloy substrate, to provide a more durable implant surface. Our long-term goal is to bring this technology to market to provide a pain-free, healthy life style for thousands of Americans undergoing joint replacement surgeries every year. The hypothesis of the project is that a wear resistant alumina coating supported by a diffusion bonded interface and a tough Ti alloy substrate exhibits higher durability than Oxinium™ against the damage by hip dislocation and the production of wear debris. In Aim 1, we will demonstrate the innovative methods that form alumina coatings with damage resistance higher than Oxinium™. In Aim 2, we will demonstrate that wear performance of the designed alumina coatings against highly cross-linked polyethylene (XPE) is better than that of Oxinium™ against XPE. A successful outcome of this project will be a durable ceramic coated head fabricated by a superior technology that will provide a combination of high wear resistance and high reliability for long-lasting total hip prostheses, with lower risk of implant failures, fewer clinical complications and revision surgeries, making a tremendous difference in the quality of life for people who need hip replacements. The phase II proposal will be focused on designing and developing the process parameters to apply designed methods to 3D femoral heads; predicting in vivo performance by hip simulator testing and biological characterization of wear debris. The global hip replacement market was worth US $6.5 billion in 2015, with a 3.9% compound annual growth rate and is expected to be worth US $9.1 billion by the end of 2024.PROJECT NARRATIVE Due to remarkable success of total hip and knee replacement procedures in treating end-stage arthritis, these are being increasingly offered to younger, more active patients which place a huge demand on durability of artificial hip joints to last for more than 40 years. Ceramic coatings are commonly used in artificial hip joints due to low wear rates but they are damaged by hip joint dislocation. To overcome this problem, we propose to develop a novel artificial hip implant that combines superior wear resistance of ceramics with superior toughness of metals by forming a diffusion bonded ceramic coating on tough metal substrate which will reduce risks of fracture, revision surgeries, clinical complications and will extend the longevity of artificial hip implants.