Five Critical Questions to Ask Your UHMWPE Supplier—An Orthopedic Innovators Q&A

By Sean Fenske, Editor-in-Chief
 
While metal is still the material most commonly associated with orthopedic implants and technology, there’s been significant momentum with regard to the influx of alternatives such as plastics for a variety of applications. As such, the critical considerations for a specific material may not always be top of mind for orthopedic device makers.
 
When selecting a new supply partner, it’s important to know what questions to ask so as to get answers about these important factors. In terms of ultra-high molecular weight polyethylene (UHMWPE), inquiries should be made about testing, sourcing, and quality. The answers a potential supplier provides could help determine if they are the right partner.
 
Fortunately, Zachary Murnane, senior R&D manager at Honeywell, provided his expertise in the following Q&A. He responds to the five important questions with his own perspective on them and explains why they are important for orthopedic device makers.
 
Sean Fenske: Before we get into the five important questions to ask, can you first explain what kind of material ultra-high molecular weight polyethylene (UHMWPE) is (i.e., characteristics) and what are some applications within orthopedics for which it is used?
 
Zachary Murnane: Some of the characteristics of UHMWPE that make it desirable for orthopedic applications include superior resistance to chemicals, fatigue, and abrasion, along with being a biocompatible material. Orthopedic sutures for ACL/PCL repair, scoliosis tethers for spine procedures, and cerclage cables for trauma surgeries are some of the orthopedic applications where UHMWPE is commonly used.
 
Fenske: Recently, some raw materials have been challenging to source. How has UHMWPE supplies been impacted by these shortages?
 
Murnane: Due to the high level of regulation within the medical industry, it can be a costly and time-consuming effort to qualify a new raw material supplier, which has historically led to many medical device manufactures having a single-sourced UHMWPE supplier. With the increased strain placed on the global supply chain during the COVID-19 pandemic, many top medical device manufacturers have prioritized finding a reliable alternative UHMWPE fiber supplier, so they can appropriately manage their manufacturing risk in compliance with ISO 14971.
 
Fenske: With biocompatibility and cytotoxicity garnering additional attention from the FDA of late, can you speak to why these are important and how UHMWPE presents with regard to these factors?
 
Murnane: Evaluating materials that will be used for in-body applications (e.g., sutures or implants) for biocompatibility and cytotoxicity is a critical part of the medical device design process, as the designing company must ensure their selected materials will not produce a toxic or immune response. Biocompatibility testing ensures the selected materials will not produce an immune response within the human body, while cytotoxicity testing validates the selected materials will not inhibit the growth of cells within the body that are trying to facilitate the healing process around an in-body device after it has been installed.
 
UHMWPE fiber meets all the biocompatibility requirements for in-body applications. UHMWPE fiber’s compliance with the cytotoxicity requirements laid out in ISO 10993 depends upon how the fiber was produced, so medical device manufacturers should look for UHWMPE fiber suppliers who are able to provide documentation that their product meets the ISO 10993 cytotoxicity standard.
 
Fenske: Is it important for a material supplier to have ISO 13485 certification? Please explain ISO 13485 and why this should matter to medical device manufacturers?
 
Murnane: ISO 13485 provides the requirements for quality management systems (QMS) of companies involved in the medical device industry. The standard is intended to help medical device companies (MDCs) setup a QMS that demonstrates consistent design, development, and production of medical devices.
 
By selecting material suppliers who are ISO 13485-certified, MDCs can decrease their regulatory risks as they will be assured the material purchased has been manufactured and tested through a well-defined and rigorously tested set of processes. If an MDC were to select a material supplier not ISO 13485-certified for a key device component, the MDC would run the risk of having higher design/development costs due to receiving materials that don’t meet their quality requirements. This could lead to repeat development trials or manufacturing delays.
 
Fenske: What type of testing has UHMWPE been through? Is it a well-established material for medical devices?
 
Murnane: UHMWPE has been used for several decades as an optimal material for use in in-body applications, such as joint replacement. Over the past two decades, UHMWPE fiber has started to be utilized within minimally invasive surgical applications, such as orthopedic joint repair and cardiovascular implants, with great success. When evaluating a UHMWPE fiber supplier, medical device companies should request the following testing results:
 

• Tensile results (denier, tenacity, breaking strength, ultimate elongation)
• ISO 10993 compliance (biocompatibility and cytotoxicity)
• FDA-approved Master Files for Device (MAF)

 
Fenske: How does UHMWPE compare to other materials, such as polyester? What are its benefits?
 
Murnane: UHMWPE is three times stronger than polyester on a per weight basis. UHMWPE’s increased strength allows medical device companies to reduce the size of their device/device components, while still achieving the same strength targets required with a polyester solution. UHMWPE has also been shown to be more resistant to fatigue and abrasion than polyester, extending the life of in-body devices versus those that use a polyester fiber. Finally, UHMWPE has a much lower coefficient of friction than polyester, making it ideal for suture applications. The natural lubricity of UHMWPE enables it to easily slide through tissue, minimizing inflation in the patient’s surrounding tissue and helping to improve patient outcomes.
 
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