Polyetheretherketone (PEEK) and Titanium (Ti) are two of today’s commonly selected materials for interbody spacer construction because of their desirable biocompatibility and mechanical properties. However, they do require further modification to support osseointegration. Although today’s most commonly utilized spinal spacers are sufficient in the area of load-carrying capacity; native, unprocessed surfaces are generally inert and have limited ability to bond and interlock with surrounding bone. They offer little resistance to shearing forces, and only result in a high rate of fusion when combined with supportive osteoconductive agents, such as Hydroxyapatite (HA).
A Short History of Spinal Interbody Materials
As early as 1930, the first-ever autograft, or graft of tissue from one place in the human body to another, was performed. By the 1960s, surgeons were using stainless steel materials; and in the 1980s, titanium and other metal alloys were available for use.
It wasn’t until the late 20th century that the spine industry was able to work with Carbon-fiber-PEEK and silicon nitride. At the start of the new millennium, nitinol, tantalum, and cobalt-chromium-molybdenum were available, and spinal interbody materials have never been the same. Throughout the last two decades, titanium and PEEK devices have dominated the landscape.
Today, 3D printers, like those at Oxford Performance Materials and 4Web Medical, create FDA-cleared 3D printed spinal fusion implants with a unique material chemistry in order to support successful bony fusion.
Titanium was introduced to orthopedics in the 1940s, and into the spine world a few decades later. Surface modification of titanium, by creating rougher surfaces, modifying its surface topography (macro and nano), physical chemical treatment, and creating a porous material with higher interconnectivity can improve its osseointegrative potential and bioactivity.
Polyetherethereketone (PEEK) Material
PEEK is a colorless, organic thermoplastic polymer with excellent mechanical and chemical resistance properties that are also retained at high temperatures. It’s robust, high-performance, and has a proven biocompatible track record. PEEK is commonly used in spinal lumbar interbody systems and cages today; often used with coatings like titanium and hydroxyapatite.
More on Spinal Interbody Coatings
Specifically, for an orthopedic implant to achieve bioactivity, its constituent materials must elicit a specific biological response at the interface of the material. This facilitates formation of a bond between the tissues and the material. This ability is often verified by in vivo tests, or soaking in simulated body fluids and investigating surface precipitation.
Hydroxyapatite (HA) Coatings
Coating the surface of the implant with osteoconductive materials like hydroxyapatite (HA) can improve osseointegration. In addition, PEEK can be coated with Ti, effectively bio-activating the coating. Surface treatments like HA are aimed at modifying the interaction with the body to generate a bioactive layer, which aids in osseointegration. This in turn creates a strong implant-bone interface, resulting in structural, biochemical and functional stability.
Hydroxyapatite (HA) Integrations
A step further, and spinal innovation has hit new ground. Cutting Edge Spine’s innovative PEEK-OPTIMA HA Enhanced, offered by Invibio Biomaterials Solutions, has similar properties to PEEK-OPTIMA Natural and a modulus similar to that of cortical bone. The hydroxyapatite is integrated into the PEEK, instead of a mere coating. This ground-breaking integration represents the present and future of spinal fusion.
To learn more about the EVOS HA, the first PEEK OPTIMA HA Enhanced Lumbar Interbodies in the United States, click here.