Artificial hip replacements can provide a lifetime of pain-free mobility to many patients, but due to the constant movement of the hip joint and the absolute necessity of accurately positioning the implant, a poorly designed or placed hip implant can lead to a cascade of problems. Aside from the patient possibly not being able to walk, higher wear rates decrease the lifespan of the implant, meaning more frequent surgeries to replace them. Higher wear rates can also lead to elevated release rates of chromium-cobalt, an alloy that makes up much of the implant, whose release into the bloodstream could cause inflammation, systemic effects, and possibly cancer.
At the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, Germany, researchers are developing a new type of artificial hip in a project called ENDURE (Enhanced Durability Resurfacing Endoprosthesis). The ENDURE hip implant addresses two common problems with current artificial hips. First, the entire joint is metal-free; the socket is made of carbon fiber-reinforced PEEK, which is a high-strength, wear resistant, biocompatible polymer composite, and the ball made of ceramic. Second, the implant provides bone-like elasticity, as the transmission of force on the slightly flexible PEEK material is modeled closely after actual biomechanics. Unlike current artificial hip implants, which are often anchored to the surrounding bone with metal screws or cement, the ENDURE implant’s surface is anchored to the surrounding bone using a unique press-fit method and a scaffold-type structure coated with hydroxyapatite, a naturally-occurring mineral found in bones.
If designing a safer, longer-lasting artificial hip weren’t enough, researchers even designed a special disposable, patent-pending tool to help surgeons place the implant. The tool uses a smart collet pin combination to attach the implant to standard surgical instruments so that surgeons and quickly and accurately insert, reposition, or remove it.