The success of a medical treatment is in the hands of highly qualified doctors. Physicians rely not only on their knowledge, but also on various helpers. Intelligent technologies are becoming increasingly common and are making an important contribution. One of these technologies is functional coatings, which are finding diverse applications in medicine.
Functional coatings are invisible, extremely thin layers that are applied to the surface of an instrument or product. They provide a specific function which the underlying material itself doesn’t possess. Medical coatings can thus have anti-microbial or lubricating functions, they can promote bone growth or prevent allergic reactions. They can be the decisive factor when it comes to the success of an operation, rapid healing or unimpeded performance of daily activities.
“Coatings on medical devices is a rapidly growing area as they often provide important and even critical functions. Changing the function of a device surface can open up complete new treatment possibilities and have a positive impact on the patient,” explains Hans Schmotzer, visiting professor at the University of Bath, U.K., and clinical expert in medical devices. And it’s for precisely this reason that the sector is experiencing such rapid growth: according to an analysis made by the American company Transparency Market Research (TMR), sales of coatings for medical devices will rise from USD 7 billion currently to around USD 11 billion by 2020.
“Requirements for surfaces vary widely. If we are talking about surgical instruments, they are very different than for an implant,” Schmotzer says.
Increased patient safety
Everything that contributes to improving patient safety is of value to a treatment. This often begins before or during an operation. Doctors need perfect lighting in order to be able to fully concentrate on the procedure. However, the lighting in an operating room is often so intense that normal instruments can reflect and produce glare. Non-reflective diamond coatings on surgical instruments can allow doctors to focus completely on the operation without distractions.
Or consider the surgical bone saw. Medical PVD coatings, such as BALINIT from Oerlikon Balzers, ensure a saw is hard enough to cut through bone, durable enough to avoid scuffing, and frictionless enough to avoid heating and damaging the tissue.
Increased compatibility of prostheses
Some devices are used and discarded, but others must last for decades. In a prosthetic knee, two metal-alloy parts and one or two pieces of high-grade plastic must stand in for the joint that lets a patient walk, stand solidly, kick a soccer ball, or ride a bicycle. The prosthetic joint’s two metallic parts must anchor solidly into the thigh bone and the shin bone on one side while sliding against the plastic pieces on the other side each time the knee bends. A metal alloy commonly used, cobalt-chromium, is hard enough to avoid wear caused by this movement—but it leaches metal ions that can irritate the bone interfering with the anchorage of the implant to the bone. Coating the bone-facing surface of the cobalt-chromium implant with a rough layer of titanium, a more biocompatible metal, and hydroxyapatite, a natural mineral component found in bone, can markedly improve the integration between bone and implant.
“The bone sees it as part of itself,” Schmotzer says.
Reduced risk of infection
According to Schmotzer, fighting dangerous bacterial infections with antimicrobial coatings is also gaining importance. “Infections are a big problem because a patient can die from an infection, and even if it’s not that drastic, an infection can cause the treatment to fail. For instance, an implant can come loose from the bone due to an infection over a period of months requiring risky and expensive revision surgery,” he adds.
To prevent these dangerous side effects, manufacturers are striving to develop antimicrobial coatings, and such coatings already accounted for the largest share—40%—of global demand for medical devices in 2013, Transparency Market Research found.
Whether it is antimicrobial, antiglare, making a metallic artificial hip function for decades or allowing a dental implant to connect better and more rapidly with the human bone – coatings on medical devices are providing treatment critical functions.
And as coatings improve, staking a patient’s life on an ultrathin coating may seem like a safe approach that we don’t want to do without.
By Mark Pearl