A partnership between researchers at North Carolina State University, Cambridge University, and University of Texas at San Antonio has developed a coating for PEEK polymer implants that significantly improves osseointegration of bone tissue with the material. PEEK, polyether ether ketone, is commonly used in ortho procedures because it can be formulated to have properties similar to bone.
The new coating is made of hydroxyapatite (HE), a naturally occurring mineral a form of which is the majority component of bone mineral. It’s welcoming of osseointegration, but it’s been difficult to make it stick to PEEK implants. The team managed to figure out how to adhere the HE to PEEK surfaces, even when those surfaces are not flat. Overcoming this major challenge, the researchers tested the material on rabbits
Some details behind the technology according to NC State:
The first step of the HA-coating technique – which was developed in Rabiei’s lab [Afsaneh Rabiei, professor of mechanical and aerospace engineering at NC State]– coats a PEEK implant with a thin film of yttria-stabilized zirconia (YSZ). The second step applies a coating of HA. The researchers then heat the HA layer using microwaves. The YSZ layer acts as a heat shield, preventing the PEEK from melting. Meanwhile, the heat gives the HA a crystalline structure that makes it more stable in the body, meaning that the calcium phosphate will dissolve more slowly – promoting bonding with surrounding bone.
In their new study, researchers tested three types of PEEK implants in a rabbit model: PEEK implants with no coating; PEEK implants with an HA coating treated only with microwaves; and PEEK implants with an HA coating treated with both microwaves and brief exposure to an autoclave in order to enhance the HA’s crystalline structure.
The researchers used microscopic evaluations of tissue cells and three-dimensional X-ray imaging to assess the performance of all three types of implants. Eighteen weeks after surgery, the researchers found that both types of HA-coated implants had more than double the bone formation of PEEK alone, with comparable bone density. The HA-treated implants also had higher bone-to-implant contact ratios than PEEK alone.
Study in journal Materials Science and Engineering: C: Hydroxyapatite coating on PEEK implants: biomechanical and histological study in a rabbit model…
Via: NC State…