All medical devices used by orthopaedic surgeons are subject to approval processes that involve testing of these products, using standards that are developed and approved by the International Standards Organization (ISO) and/or the American Society for Testing Materials International (ASTM International). These standards are typically developed by a team of academic and corporate engineers, along with representatives from the U.S. Food and Drug Administration (FDA), who participate in an unofficial manner.
The need for clinician input, however, is increasing. Recently, outcome measures for patients who receive medical devices have been added to the standards development activities of ASTM International. As a result, involvement by surgeons and clinicians is key to ensuring that the devices and outcome measures being used are both safe and appropriate for patients.
Many orthopaedic surgeons may not be aware of the multiple pathways that exist to obtain approval for a device when a custom or unique situation presents itself. A familiarity with the current pathways for medical device approval through the FDA not only helps us as orthopaedic surgeons understand how the products we use came to the market, it can also help us navigate the proper pathways when a custom or humanitarian need arises.
Many surgeons may not realize what avenues are available to them when treating patients with difficult surgical reconstructions. For example, although devices currently being marketed are approved for specific uses, they may also be used in other ways (off-label use). Understanding how to apply this concept can be extremely helpful in an orthopaedic practice.
Finally, I hope that this article will shed light on the current standards-setting activities of the FDA and ASTM International and convince readers to get involved. The safety, efficacy, and clinical applicability of standards now under development depend on the involvement of AAOS members.
FDA approval pathways
The FDA has established the following four main pathways for device approvals:
- Investigational Device Exemption (IDE)
- Premarket approval (PMA) process
- 510K process
- Humanitarian Device Exemption (HDE)
Of these four pathways, the 510K process is the one most used for approval of orthopaedic devices. Products approved through the 510K process are typically class II devices (see “FDA Device Classifications”). They generally have a predicate device for comparison and can meet the proof of equivalence to the approved device through the application. The 510K applications are typically reviewed by the FDA within 90 days. If the product is deemed substantially equivalent to a previous predicate device, the application can be approved within that time frame or the FDA may ask for further information before granting approval.
The PMA process is used for class III devices or devices that are not found substantially equivalent to a previous class I or II predicate device. The PMA pathway is the most involved and includes the most clinical and basic science studies; the approval process typically takes years.
IDE trials are typically considered part of the PMA approval process, along with other substantial scientific proofs of safety and effectiveness. Surgeons who participate in an IDE must obtain consent from the patient.
The HDE applies to devices used to diagnose or treat conditions that affect fewer than 4,000 individuals per year. These devices are exempt from proof of effectiveness but must pose no unreasonable risk to the patient and require Institutional Review Board approval at the location of use.
A custom device path for medical device use is also available when the device meets a specific set of criteria. For example, the device can only be used once under this path and is unique to the needs of the patient or application for which it is being used. The custom device path typically takes 30 days for companies to approve usage, using their own and/or FDA regulatory paperwork. Using a custom device, however, may make revision of complex deformities or older implants more difficult.
Surgeons must remember that simply asking a company for a smaller version of an approved device does not necessarily make it a “custom” device under this definition. Although this may seem a strict and narrow definition, the FDA uses it to help prevent “back door” approval of a device that does not meet guidance standards for that type of device. For example, a smaller total hip femoral component may not meet the fatigue standards set for these types of devices because it is too small.
Orthopaedic surgeons also have options for off-label use of a device but must have a legitimate reason for doing so. When using a drug or device off-label, the surgeon must discuss the off-label use with the patient during the surgical consent process. For more information on off-label use of devices, visit the FDA website (www.fda.gov).
The off-label use of an approved device is always possible, based on the surgeon’s discretion. IRB approval may be required if the surgeon is using any data for research (See “FDA Regulatory Status and Informed Consent,” AAOS Now, May 2012).
The FDA may also require postmarket surveillance studies (also called 522 studies) of devices after they have been approved, and the use of these studies is likely to increase. In response, the ASTM International is attempting to standardize clinical outcome measures for clinical studies in specific areas. It is also seeking to standardize orthopaedic implant product labels to decrease errors in the operating room.
Why get involved?
During an AAOS-ASTM–sponsored symposium last May, 10 new standards were suggested relating to metal-on-metal total hip implants. These standards need to be developed to ensure the safety of these devices and the monitoring of patient variables (such as through serum assays and metal artifact reduction sequence magnetic resonance imaging (MARS MRI).
The need for device standards is significant, and the overlap of activity between their development and orthopaedic practices underscores the need for orthopaedic surgeons to become involved. The Academy’s Biomedical Engineering Committee and its Biologic Implants Committee are involved in ASTM standards development, but any surgeon can be part of the process. Most standards committee meetings can even be accessed through online conferencing (WebEx), saving both time and travel dollars.
As orthopaedic surgeons, we deal with medical devices that have received FDA clearance and meet ASTM or ISO standards. We should understand how these standards are developed and how great the need is for our clinical input. As our surgical specialty becomes more dependent on advanced medical devices, we must be involved to ensure that the approval and testing of these devices are clinically relevant and that our patients have access to the safest and most efficacious devices.
William M. Mihalko, MD, PhD, chairs the AAOS Biomedical Engineering Committee. He can be reached at email@example.com
AAOS fellows who are interested in getting involved in ASTM standards activities should contact Dr. Mihalko (firstname.lastname@example.org) concerning medical device standards or Katherine Sale (email@example.com) concerning biological or tissue engineered medical products.
All clinically relevant ASTM standards development can be viewed on the ASTM International website (www.ASTM.org) under the F04 (Committee on Medical Devices) subheading.
FDA Device Classifications
Class I—Devices that present little risk to the public and are generally recognized as being both safe and effective. This classification is subject to minimal FDA oversight. Examples of Class I devices include cast materials, crutches, and wheelchairs.
Class II—Devices determined by the FDA to offer some additional risk to the public beyond that of Class I devices. Device uses falling into this category must comply with the general requirements for Class I devices and, in addition, any other performance standards developed by the FDA. Examples of Class II devices include intramedullary nails, bone screws, and plates used for long bone fractures.
Class III—Devices for which general regulatory controls are not sufficient to ensure safety and effectiveness, that may offer a substantial risk to the public, and for which sufficient information to establish a performance standard does not exist. Class III devices are generally considered to be “new” medical device uses requiring a showing of safety and effectiveness through a premarket approval prior to labeling for the intended use. Examples of Class III devices include ligament replacements, bone substitutes, and metal-on-metal hip replacement systems.