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The Role of Coatings in Orthopedic Instrumentation

Wed, 10/17/2012 - 4:07pm
Don Garcia

High-performance coatings are being used across just about every device sector and on a variety of devices. Coatings can make components and the devices themselves stronger, safer, and more cost effective. This article looks at PVDF coatings and the array of benefits they offer when used on orthopedic tools.

 

In addressing the need for durability, the entire instrument may be coated with PVDF, enabling the tool to withstand repeated autoclaving as well as the inevitable rough treatment imposed upon it during its daily use.It has been said that Noah’s ark was coated inside and out with a unique concoction of pitch designed to seal his seafaring vessel. This is the first recorded coating application and ever since, people have relied upon coatings to improve the lifespan, appearance, safety, and performance of substrates that would otherwise be adversely affected by their ambient environment. Today’s coating technology—while considerably more complex than Noah could have ever imagined—is no less important.

The Health Care Act will be putting pressure on all medical branches to reduce prices. This will be true even though material and regulatory costs are increasing. The orthopedic industry is no exception. While surgeries are growing in volume and complexity, health insurance companies are increasingly looking for better value. The reduction of operational costs has become an important factor and many formerly disposable instruments are being replaced with re-usable ones. With that phenomenon, however, comes the need for re-usable instruments that are impervious to bio-burden and able to withstand repeated sterilization with harsh chemicals.

Orthopedic surgical tools are used to perform surgical procedures that range from cutting and suturing to more invasive operational procedures that are best left undescribed here. It can be said, however, that the life of an orthopedic surgical tool is not a gentle one. In addition to imparting specific activity-based, useful characteristics, the coatings on re-usable tools must withstand the rigors of continuous daily use, rough handling, autoclaving (or other means of sterilization), fast-paced selection, and accurate decision making.

PVDF
Although there are many other coatings, such as PFA (perfluoroalkoxy) or ECTFE (ethylenechlorotrifluoroethylene), that can be employed to enhance the performance and longevity of these instruments, the focus of this article is on PVDF. PVDF (polyvinylidene difluoride) is a fluorocarbon-based polymer coating used on orthopedic surgical tools. The coatings are durable, chemical resistant, and inert, with excellent dielectric strength (1,500 V/mil) and lower cure temperatures (500°F). Available in a wide variety of colors, this coating enhances appearance as well as performance and has a long history in reusable medical devices/instruments. PVDF is biocompatible and FDA compliant.

In order to fully appreciate PVDF and its stated characteristics, one might elaborate on the practical applications for use within the surgical suite. As previously mentioned, PVDF coatings demonstrate excellent dielectric strength. For instance, when applied to a cauterizing instrument, the coating—applied on handles, triggers, and other specific areas on the device—restricts RF current to the “business end” or tip of the instrument. As a result, patients’ incisions are cauterized with precision while the surrounding tissue and surgical personnel remain unharmed.

In addressing the need for durability, the entire instrument may be coated with PVDF, enabling the tool to withstand repeated autoclaving as well as the inevitable rough treatment imposed upon it during its daily use. Additionally, PVDF can better tolerate the newer, more aggressive sterilizing solutions employed by hospitals today.

Unlike traditional inks or dyes, PVDF markings withstand autoclaving without fading of the marking.Almost as important as the durability of a coating is the ability to mark an instrument with color. Colored PVDF coatings are often used to distinguish an instrument’s coated surface from its non-coated surface, thereby speeding orientation in the fast-paced operating environment. Sometimes, it is necessary to color code instruments—either with different colors on different instruments or multiple colors on the same instrument—in order to make accurate selection and quick decision making possible. Measurement markings can also be applied as coatings, allowing the surgeon to have a continuous visual status. These markings produced with high performance polymers are able to withstand the same rigors, unlike traditional inks or dyes, and PVDF markings withstand autoclaving without fading of the marking. Coatings are fused to the instrument in such a way that they do not flake, chip, or become dislodged, and as such, they do not have the potential to accumulate bio-burden. Further, unlike other alternatives, such as heat-shrink products, coatings can be applied to complex geometries or selectively to a device so that only certain areas are coated.

There are hundreds of medical coatings, each with their own set of properties that can be used to lower the overall product life costs. Regardless of whether the application of the coating is done in-house or by using an independent coater, however, the process of application is as important as the material selection itself. The process should be well documented and adequate controls should be instituted to ensure high quality and consistency. The result is an instrument with a product lifecycle cost substantially less than disposable instruments, providing value for both the manufacturer and user.

Don Garcia is director, research & development at Boyd Coatings. In his more than 30 years at Boyd Coatings, he has had hands-on technical experience in literally every facet of the coatings business. Areas of specialty range from aerospace and medical to military and high-reliability, high-performance coatings.

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