By Sean Fenske, Editor-in-Chief
 
Traditional medical devices used within the body are often intended to last for the patient’s lifetime. As such, they are developed with strong, durable materials that will not succumb to the harsh environment of the human body. But with many surgeons and healthcare professionals seeking more natural healing alternatives, device makers are expanding their use of materials and exploring options that can breakdown in the body as healing occurs.
 
Bioresorbable materials are an option that meet this need. They can provide support to a part of the body while healing takes place and then dissolve once the area no longer requires the device. The material is expelled through natural processes and leaves nothing behind.
 
As exciting as these types of materials are, the challenges of working with them can be significant. As such, Raghu Vadlamudi, chief research and technology director for Donatelle, provided insights on a number of factors device manufacturer should consider if they are looking to develop products from these materials. While the companies may be quite acquainted with molding with more traditional resins, bioresorbable materials present a different set of dynamics that could be unfamiliar to them.
 
Sean Fenske: What is truly meant by bioresorbable molded devices? Does the body actually absorb the device?
 
Raghu Vadlamudi: Bioresorbable devices are manufactured using natural or synthetic polymers and metals that can be broken down by hydrolysis—chemical breakdown due to reaction with water. Once they are implanted in the body, the material will be broken down and absorbed by the body, not requiring removal like some of the current devices manufactured using stainless steel or titanium. The examples of bioresorbable polymers are Polylactide, Polyglycolide and their copolymers. Metals such as magnesium are being used to manufacture bioresorbable devices.
 
Fenske: What applications is this technology best indicated for? What are the advantages?
 

Vadlamudi: Sutures and staples used for surgical closures were the early applications for this technology. Over the years, bioresorbable materials became popular in the orthopedic and cardiovascular industries. Interference screws and suture anchors are some of the widely used products in the orthopedic industry, whereas tissue scaffoldings are popular in the cardiovascular field. The advantage with bioresorbable materials is it overcomes drawbacks associated with traditional implant materials, such as difficulty in imaging, need for removal, restenosis, etc.
 
Fenske: What are the most significant factors bioresorbable device makers should keep in mind when designing or spec’ing for molding?
 
Vadlamudi: The bioresorbable device maker needs to take into account price and material availability, along with the knowledge in handling and processing the material. It can become expensive if the device manufacturer does not have the expertise in-house or access to a skilled supplier. Processing bioresorbable materials demands strict adherence to good manufacturing practices with a suitable environment. Consistency is critical here.
 
Fenske: What material considerations does the device manufacturer need to keep in mind?
 
Vadlamudi: The device manufacturer needs to consider the limitations of bioresorbable materials, especially polymers because of their inferior strength compared to metals. They must also consider the material’s reactivity with the tissue, as well as the absorption rate needed. Material properties such as crystallinity and molecular weight, in addition to product design, environment where the product is going to be implanted, and the processing methods (molding and sterilization) must also be considered, because all of these factors will affect the material performance after implantation.
 
Fenske: What challenges does adding pharmaceutical elements introduce to the molding process?
 
Vadlamudi: Adding pharmaceutical elements increases the level of difficulty in the molding process. Equipment needs to be modified to accommodate these heat-sensitive materials. For example, material extruders and dryers need to be sized to handle these expensive materials in order to minimize excessive heat exposure and degradation. Material degradation during processing will result in inconsistent absorption rates after the implantation, which defeats the original purpose.
 
Fenske: Does the molding process for bioresorbable components/devices differ at all from a more traditional injection molding process (i.e., production time, volume limits, etc.)?
 
Vadlamudi: The molding process itself is not that different. Actually, it’s the same. However, traditional polymers are more forgiving when it comes to degradation during processing. Material cost is another important factor that results in optimization of mold designs to minimize waste.

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