The Food and Drug Administration (FDA), the US regulating authority in the sphere of medical devices, has published several guidance documents addressing product-specific performance criteria for certain types of medical devices, including spinal plating systems and orthopedic non-spinal metallic bone screws and washers.
In particular, the new guidelines cover the aspects to be considered in the context of the approach based on the safety and performance of medical devices. Both documents actually constitute final versions of the respective draft policies issued by the FDA earlier in September 2019. However, the industry representatives still may submit their comments and suggestions regarding the matter – the FDA appreciates the feedback from all the parties involved in operations with medical devices and states that all comments and suggestions would be taken into consideration when developing the revised versions of the guidelines.
It is also important to mention that due to their legal nature, these guidelines do not introduce any mandatory requirements the industry representatives shall follow, but rather provide additional clarifications and recommendations regarding the current regulatory framework. Thus, an alternative approach could be applied, providing that it complies with the applicable regulations and is agreed with the Agency in advance.
Under the general rule, a medical device manufacturer applying for marketing authorization for its medical device shall make references to the similar medical device already placed on the market (the predicate), and provide a comparison using the performance criteria. The present document introduces a different approach under which a medical device manufacturer may refer to the performance criteria set forth therein to demonstrate substantial equivalence instead of making a direct comparison to the predicate.
According to the suggested procedure, the medical device manufacturer applying for marketing approval shall provide a results summary for all tests the medical device in question was subject to, together with the other documents required, including the Declaration of Conformity. In particular, the FDA expects the applicant to provide a results summary, test protocols, or complete test reports.
The new guidelines also contain references to the FDA-recognised consensus standards the medical device manufacturers may use to demonstrate compliance with the applicable requirements.
The Agency mentions that it is entitled to request the medical device manufacturer to provide additional information reasonably necessary to assess the case and medical device in question. In certain cases, additional testing could be also required.
Performance Criteria for Spinal Plating Systems
The first document published by the FDA is dedicated to the performance criteria for spinal plating systems to be applied in the context of the Safety and Performance Based Pathway – a special framework the medical device manufacturers may apply when placing their products on the US market.
The scope of the present FDA guidance covers the anterior cervical or anterior/lateral thoracolumbar spinal plating systems regulated under 21 CFR 888.3060 under the code KWQ. These products are Class II medical devices under the risk-based classification. The medical devices covered by the guidance are intended for the purpose of stabilizing the spine of fusion. At the same time, the authority also mentions that plating systems intended to be attached to the posterior spine or the occiput are not covered by the present policy.
The medical devices addressed in the document usually consist of plates and associated fixed or variable angle screws manufactured using the materials compliant with the applicable voluntary consensus standards, such as:
- ASTM F136 Standard Specification for Wrought Titanium-6 Aluminium-4 Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications (UNS R56401),
- ASTM F1295 Standard Specification for Wrought Titanium-6 Aluminium-7 Niobium Alloy for Surgical Implant Applications (UNS R56700),
- ASTM F67 Standard Specification for Unalloyed Titanium for Surgical Implant Applications (UNS R50250, UNS R50400, UNS R50550, UNS R50700).
The guidance also provides the dimensional ranges the device`s parameters should fall within. The appropriate table indicates the size ranges for such parameters as plate length and thickness, screw diameter and length, and also the number of levels treated. The table provides the aforementioned parameters for cervical plates and thoracolumbar plates separately. The Agency also mentions that the dimensional ranges provided in the guidance are actually based on the information from 510(k) submissions regarding the medical devices for which the substantial equivalence has been already confirmed.
The regulating authority states that certain spinal plating systems could not be placed on the market under the Safety and Performance Based Pathway. In particular, this framework could not be applied to the following devices:
- Devices that affix to the posterior spine or the occiput,
- Devices with coatings,
- Combination products,
- Additively manufactured devices,
- Buttress plating systems,
- Resorbable devices, and certain other products.
The Agency also refers to the general guidance on 510(k) applications for spinal systems like the one covering all medical devices of this type.
Performance Criteria for Orthopedic Non-Spinal Metallic Bone Screws and Washers
The second guidance document issued by the FDA describes the policy for orthopedic non-spinal metallic bone screws and washers in the context of the Safety and Performance Based Pathway. The document introduces the same regulatory approach as for spinal plating systems as described hereabove.
The scope of the document covers non-spinal metallic bone screws and washers subject to regulation under 21 CFR 888.3040 with the product codes HWC and HTN. These products are Class II medical devices in accordance with the risk-based classification used in the US.
With regard to the scope of the guidance, the Agency places an emphasis on the following:
- The policy covers bone screws intended for orthopedic non-spinal fixation, osteotomy, or small joint fusion or arthrodesis.
- The policy also covers the washers intended for use with bone screws only to aid in load distribution at the screw head/bone interface.
- The policy does no cover the bone screws or washers intended for mandibular, maxillofacial, cranial, and orbital fracture fixation, or for use in the spine.
The FDA also provides the list of voluntary consensus standards the devices covered by the scope of the present guidance should meet in the part of materials used.
According to the document, the scope of the policy does not cover medical devices that have:
- Complex geometries or modularities,
- Unique technological characteristics,
- Elements based on the use of surgical techniques or associated instruments outside the standard of care.
The regulating authority additionally mentions that combination products and resorbable devices are also falling outside the scope of the present guidance.
The document also outlines the testing performance criteria, including the ones applicable for mechanical bench testing, sterilization and reprocessing validation, and biocompatibility evaluation.
Summarizing the information provided here above, the new guidance documents issued by the FDA describe the approach for certain implantable medical devices to be applied in the context of the Safety and Performance Based Pathway. In particular, the Agency highlights the performance criteria the spinal plating systems and orthopedic bone screws and washers should meet in order to comply with the applicable requirements. The guidelines also provide additional clarifications regarding the testing and evaluation methods to be applied before applying for marketing authorization.
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