Because of their strength and light weight, carbon-fiber-reinforced plastics (CFRPs) are finding many varied applications in the automotive, aviation, aerospace and sporting goods sectors. Increasingly, the material is making inroads in medical technology, as well, although it is not widely used. One area where it has made a noticeable impact is in prosthetics and trauma devices—implants that hold together fractured bones. Invibio (Thornton Cleveleys, UK) is in the vanguard of these medical applications: PEEK-OPTIMA, the first implantable PEEK polymer, was launched in 1999, followed by a carbon-fiber-reinforced (CFR) PEEK material in 2006i.
Today, Invibio’s PEEK-based biomaterials are used in a range of medical applications, including spine, arthroscopy, joint reconstruction, trauma, dental, and cranio-maxillofacial procedures. PlasticsToday spoke with Sherri Gambill, Trauma Technology Manager at Invibio’s offices in West Conshohocken, PA. She says that fracture fixation, her main professional focus, is where the material has great potential.
First and foremost, said Gambill, CFR-PEEK are thermoplastic, not thermoset, composites and they have demonstrated the potential to improve healing and reduce revision rates in trauma proceduresii, which can get patients back on their feet quicker. An additional benefit is the material’s radiolucency, which offers surgeons unimpeded visibility of the fracture site during and after surgery. With better visibility of fracture healing during follow-up visits, a surgeon can have increased confidence in returning patients to load-bearing activities. These clinical benefits are due to the material’s elastic modulus, fatigue life and radiolucencyiii. They provide significant advantages over titanium and stainless steel, which are routinely used in these applications. “Metal has been used very successfully for a long time, but these are areas where we see the potential for improvement with our materials,” said Gambill.
With a CFR PEEK–based device, the surgeon can see the bone behind the plate in all planes. That’s not as easy to do when a metal plate is used. “Radiolucency enables not only an easier, but a more accurate inter-operative assessment of the fracture reductioniv, v, vi,” explained Gambill. It’s also safer because the surgeon can see all sides of the bone and, if he or she is operating in an area close to a joint, the risk of screw perforation is decreasedi, she added. Clinical studies have shown that there are fewer cases of screw perforations in CFR-PEEK devices than in metallic devices, said Gambilliii, vii, viii.
The material’s radiolucency also can reduce the time it takes to perform the procedure because the surgeon has unimpeded challenges with visibility. Gambill cited one studyiv that shows an 18% reduction in the full operative time for a complex fibula fracture when a CFR PEEK plate is used instead of a metal one.
The fatigue life of CFR PEEK versus metallic devices is also important because there is a “race between when the implant will fail and when the fracture will heal,” said Gambill. Invibio has conducted tests based on ASTM standards of identical parts made from CFR PEEK and titanium that reportedly show improved fatigue life for the polymer-based deviceix. “If you can extend the window of time for healing, you can provide the patient more opportunity to heal, which may result in fewer revision surgeriesi, iii, iv, v, x, xi, xii ," said Gambill.
CFR PEEK also has engineering and design advantages, she added.