The article provides an in-depth review of the regulatory requirements for facet screw systems. 






The Food and Drug Administration (FDA or the Agency), has published a guidance document dedicated to the performance criteria for safety and performance-based pathway for facet screw systems. The document describes in detail the regulatory requirements such products should meet to be allowed for marketing and use in the US. It is important to mention that FDA guidance documents are non-binding in their legal nature, and are intended to provide additional clarifications regarding the applicable requirements, as well as recommendations to be taken into consideration by medical device manufacturers and other parties involved. At the same time, the authority explicitly states that an alternative approach could be applied, provided such an approach is in line with the current legislation and has been agreed with the authority in advance. 

Under the framework described in the guidance, submitters planning to submit a 510(k) using the Safety and Performance Based Pathway for facet screw systems will have the option to use the performance criteria proposed in this guidance to support substantial equivalence, rather than a direct comparison of the performance of the subject device to the of a predicate device. The document also contains references to the FDA-recognised voluntary consensus standards the manufacturers may use to demonstrate substantial equivalence. 

The scope of the present guidance covers the facet screw systems consisting of metallic bone screws and optional washer components. The authority additionally mentions that such products are unclassified. The products covered by the scope of the guidance are intended for bilateral immobilization of facet joints to stabilize the spine as an aid to fusion, while the optional washer components are intended for use with the facet screw to aid in load distribution at the screw head/bone interface. 

The authority also mentions that some of the facet screw systems are not covered by the scope of the present guidance. These systems include, inter alia, the following ones:

  • Combination products;
  • Resorbable devices;
  • The device with coating;
  • Additively manufactured devices;
  • Devices that utilize surgical techniques or associated instruments outside the standard of care;
  • Devices with complex geometries, or unique technological characteristics (e.g., unique screw thread, modularity, fenestrations);
  • Devices sterilized using novel sterilization methods as described in FDA’s guidance “Submission and Review of Sterility Information in Premarket Notification (510(k)) Submissions for Devices Labeled as Sterile”. 


Device Design Characteristics 

According to the guidance, when assessing the construction of facet screw systems, the appropriate consensus standards should be used. The assessment includes a dimensional comparison to ensure the actual dimensions of the device in question meet the respective range outlined in the standard. The authority further highlights some important technical aspects to be considered when assessing the dimensions to ensure proper operations of the system and all components thereto. 

The authority also reserves the right to request additional information regarding the product in question, should it be reasonably necessary to complete the assessment, including the assessment of eligibility for the Safety and Performance Based Pathway, while medical device manufacturers are encouraged to get in touch with the authority and discuss the scope of testing required to substantiate the claims before applying itself. 




Testing Performance Criteria 

As it is stated by the FDA, if [the] device is appropriate for submission through the Safety and Performance Based Pathway, and [the applicant] chooses to use that option, [the authority] does not expect [the applicant] to provide direct comparison testing against a legally marketed predicate to demonstrate substantially equivalent performance characteristics. According to the guidance, the authority expects the applicant to submit a summary of all the tests conducted to evaluate the performance of the medical device in question, together with a Declaration of Conformity. As it was mentioned before, the FDA is also entitled to request additional information regarding the product itself and the testing it was subject to. It is further explained that the information to be submitted by the applicant should include, inter alia, test protocols or complete test reports.

The FDA pays special attention to the mechanical testing and methods to be applied in this respect. According to the guidance, the appropriate testing should be duly performed to assess mechanical strength. The authority additionally emphasizes that such testing should be performed using a final device to ensure the reliability of its results. In certain cases, it is allowed to use near-final devices, provided that the procedures the device should still undergo to be considered final are not expected to impact its characteristics (e.s., sterilization), however, the use of medical devices that are not final should be duly justified. Concerning the testing methods, the FDA refers to the appropriate voluntary consensus standard – ASTM F2193, which describes the particular testing methods to be followed for this type of medical device. In each situation, the worst-case scenarios should be assessed. Upon completion of the said testing, the appropriate report should be prepared and further submitted to the FDA together with the other documents included in the submission dossier. It is important to mention that any deviations from the initial study plan should be duly justified. In certain cases, the deviations could result in a comparison being determined as invalid. 

The authority further describes in detail the particular testing methods to be used, and also outlines the most important aspects to be considered to ensure the accuracy and reliability of the results, and also indicates the acceptance criteria to be followed when validating conformity to the applicable requirements. 

The scope of testing covers, inter alia, sterilization, and reprocessing validation. The said testing should demonstrate the cleanliness and sterility of the device in question, or the ability to clean and sterilize to the extent required by the respective requirements. The applicant is expected to provide detailed and exhaustive information about the packaging used, its features, and its characteristics in the context of ensuring sterility of the device it contains during the transportation and within the whole shelf life period. 

In summary, the present FDA guidance provides an overview of the regulatory requirements and acceptance criteria to be taken into consideration when assessing the safety and performance of facet screw systems intended to be marketed and used in the US. The document provides recommendations regarding the testing methods to be used to ensure the reliability and admissibility of the results and also outlines the scope of applicable standards. 






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