Posted 11 February 2016
By Zachary Brennan
The US Food and Drug Administration (FDA) on Thursday released new draft guidance to help Class II and III orthopedic device developers understand what type of information to include in their submissions for devices using ultrahigh molecular weight polyethylene (UHMWPE) material.
FDA says it developed the draft guidance document, which is open for comments for the next 90 days, for companies looking to characterize and test orthopedic devices that use UHMWPE materials, such as conventional UHMWPE, highly cross-linked UHMWPE, and highly cross-linked UHMWPE containing vitamin E.
The guidance focuses on what FDA recommends should be included in a 510(k), de novo requests, premarket approval (PMA) applications, humanitarian device exemptions (HDE) or investigational device exemption submissions (IDE) to FDA in order to characterize the UHMWPE material, which includes crosslink density, trans-vinylene index (TVI), oxidation index (OI), crystallinity, melting temperature and free radical concentration.
“For some of the properties, such as tensile properties, impact resistance, and density, acceptance criteria are set forth in ASTM F648, ‘Standard Specification for Ultra-High-Molecular-Weight Polyethylene Powder and Fabricated Form for Surgical Implants,’” FDA says. “If the material meets the acceptance criteria, no additional information will typically be requested.”
Other properties, FDA notes, such as biaxial mechanical properties, fatigue crack propagation resistance, and consolidation, are comparative and when submitted in a 510(k), the results should be compared to a predicate device with the same intended use. When submitted in a de novo, PMA, HDE, or IDE, FDA says the results for these properties and their anticipated impact on device performance “should be thoroughly discussed and supported with available literature and a scientific rationale and incorporated into the benefit/risk analysis for the device.”
In terms of biocompatibility, FDA says for Class II devices, if the subject device has identical UHMWPE materials and manufacturing processes as a predicate device, with the same type and duration of patient contact, it’s recommended that the company identify the predicate device as part of its biocompatibility evaluation in lieu of providing specific testing.
And as far as other general recommendations, FDA says companies should not “package UHMWPE-containing unstable free radicals in air-permeable packaging because shelf-aging may degrade the mechanical properties of UHMWPE. The shelf life of UHMWPE that has not been exposed to ionizing radiation, or that has been irradiated but packaged in inert environment, is limited by the integrity of the packaging material.”
FDA Draft Guidance on Characterization of Ultrahigh Molecular Weight Polyethylene (UHMWPE) Used in Orthopedic Devices