Device Disasters: How Daisy Chain Devices Leave Safety Behind


This is the second post in a three-part series about medical device regulation. In our first post in the Device Disasters series, we explained how grandfathered medical devices came to be and why they are still important to the modern U.S. Food and Drug Administration's (FDA) medical device approval system.

Today, we are going to discuss the daisy chain of approvals that stem from the agency's 510(k) clearance process, and the impact these approval strings have had on current devices. In the medical device industry, a daisy chain refers to devices that rely on clearances of earlier devices to avoid a full safety review.

How the 510(k) Clearance Process Creates a Daisy Chain of Devices

  1. Device A is cleared or approved by the FDA.
  2. Through the 510(k) clearance process, Device B gains clearance by proving that it is "substantially equivalent" to Device A. Device A is now known as the predicate device of Device B.
  3. After receiving FDA-clearance, Device B can help similar Device C gain entry to the market. Device C can then help Device D and so on and so forth.
  4. The pattern continues until the latest device cleared in the chain holds little resemblance and may even prove to be inferior to Device A, the original predicate device in the series.

The Trouble with Daisy Chain Approvals

The 510(k) process was created to streamline the FDA's oversight of medical devices. Rather than make all devices undergo the extensive Premarket Approval (PMA) process required of high-risk Class III devices, the 510(k) clearance pathway offers device manufacturers a quicker way to gain FDA-clearance for their Class II or medium-risk devices.

Unfortunately, by only requiring proof of "substantial equivalence," the FDA's 510(k) clearance process frequently ushers medical devices onto the market without evidence of safety or efficacy.

Scrutinizing the 510(k) Process

In 2009, the 510(k) process underwent scrutiny from the Institute of Medicine (IOM), a well-respected scientific organization that reviews public health issues, at the request of the FDA. The IOM-appointed panel released their final report in 2011 and shocked the FDA and the medical device industry when they proposed scrapping the Class II device approval system. The panel concluded that the system could not be improved and recommended building a new system from the ground up, one that would test these Class II devices for both safety and efficacy before market release.

Critics of the report, especially those in the device industry, claimed that devising a new system could cause more safety issues and impede innovation. In the end, the FDA did not throw out the 510(k) clearance process.

Daisy Chain Devices Gone Wrong

Imagine having a device implanted in your body that was never tested on a human, reviewed for safety or proven to work. This exact situation happened to thousands of patients in the decades following the Medical Device Amendments of 1976, which created the 510(k) process.

In 2018, Netflix released a chilling documentary, The Bleeding Edge, which highlighted the immeasurable damage done by three popular, implanted medical devices. Two of these devices came to market on the heels of serial daisy chain approvals. They were 510(k) cleared by proving substantial equivalence to similar but assuredly unequal predicate devices as patients later learned.

Device Disaster Reality: Hip Implants

While substantially equivalent to other hip replacement devices on the market, the metal-on-metal hip implant featured in the Netflix documentary had one major difference from its predecessors. It was made of cobalt. This material difference between the hip device and its predicate device was insignificant enough to pass the "substantially equivalent" test, but it was enough of a difference to cause cobalt poisoning in patients. Had the manufacturer been required to prove the safety and efficacy of the device with its new materials, this hip implant may not have made it on the market.

Metal poisoning is just one alarming side effect that has been reported from modern hip implants. Patients have also experienced allergic reactions, dislocation, infection, damage to nerves, bone loss, and device detachment from different hip implant devices cleared through the FDA's 510(k) approval.

Many patients suffering complications from hip replacement surgery or side effects from the hip devices have had to undergo revision surgery or additional therapy to treat the complications. Tens of thousands of these patients and their families have filed hip replacement lawsuits against the device manufacturers for selling dangerous products and doing little to warn patients about the risks associated with the surgery and devices.

In our next edition of Device Disasters, we will take a look at how the FDA's alternative reporting system allowed manufacturers to hide device defects from consumers and healthcare providers, thereby endangering the health and safety of countless patients.

Authored by Katy Moncivais, Ph.D.Medical Editor
Photo of Katy Moncivais, Ph.D.
Katy Moncivais holds a Ph.D. in Biomedical Engineering from The University of Texas at Austin. She’s an experienced Regenerative Medicine Consultant with a demonstrated history of working in the hospital & healthcare industry. Skilled in adult stem cells, medical devices, biomechanics, bacterial and mammalian cell culture, and regenerative medicine, she provides guidance on an array of topics affecting consumers. In her role at, Dr. Moncivais works alongside the writing and research staff to help deliver fact-based news stories to consumers. Her unique professional history alongside her rigorous educational background allows her to contribute to a variety of consumer-focused topics with a fresh perspective. In addition, Dr. Moncivais reviews portions of medically driven content to ensure scientific accuracy.
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