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How Did the Problems Begin with the Depuy ASR Artificial Hip? (A Little History)

First, a little history is in order to see how a medical device like a Depuy ASR artificial hip gets to the market (and ultimately, into your body).

What is a total hip replacement?
A “total hip replacement” replaces the body’s hip joint with an artificial one, and these artificial hips are usually made out of metal or plastics. A total hip replacement typically consists of four separate parts: (1) a stem, (2) a head, (3) a liner, and (4) a cup (called an “acetabular cup” or shell). After the surgeon hollows out the patient’s femur bone, the stem is implanted. The head is a metal ball that is fixed on top of the stem. The femoral head forms the hip joint when it is placed inside the liner and the cup (the “acetabular shell”).

What is a Depuy ASR Artificial Hip?
The Depuy ASR Hip has a different design from previous artificial hip replacement systems, one that puts the metal ball directly in contact with a metal cup. The design of the Depuy ASR Hip was never adequately tested by Defendants, and the Depuy ASR Hip was never specifically approved by the FDA as being safe or effective for the product’s intended purpose.
This can get complicated, but a Depuy ASR Hip is known as a Class III medical device. Class III devices are defined as those that work to sustain life, are important in preventing impairment of human health, or those which could pose unreasonable risks to patients.
The federal statute which regulates these medical products (the “MDA”) require Class III medical devices like the Depuy ASR Hip to undergo premarket approval by the FDA, a process which requires the manufacturer to design and implement a clinical investigation and to submit the results of that investigation to the FDA.

Premarket approval is designed to protect the public from untested medical products.
Premarket approval is a rigorous process that requires a manufacturer to submit an extensive application that includes full reports of all studies and investigations of the device’s safety and effectiveness; a complete statement of the device’s components and properties, and the principles of operation; a full description of the methods used in the manufacture, processing, and packing and installation of such medical device; samples or device components; and an example of the proposed labeling.
The FDA may grant premarket approval only if it finds there is reasonable assurance that the medical device is safe and effective and that any probable benefit to health from the use of the device outweighs any probable risk of injury or illness from such use.

The Depuy ASR Artificial Hip did not obtain premarket approval.
A medical device on the market prior to the effective date of the MDA—referred to as a “grandfathered” device—was not required to undergo premarket approval. This can be confusing, but a medical device marketed after the MDA’s effective date may bypass the demanding premarket approval process if the device is “substantially equivalent” to a “grandfathered” pre-MDA device (a device approved prior to May 28, 1976). This exception to premarket approval is known as the “510(k)” process and requires a manufacturer simply to notify the FDA under section 510(k) of the MDA of its intent to market a device like an artificial hip at least ninety days prior to the product’s introduction on the market, and to explain the device’s substantial equivalence to a pre-MDA device. The FDA may then approve the new device for sale in the United States.
In 2005, the year when the Depuy ASR Hip was approved for sale, the FDA approved the marketing of 3,148 devices under section 510(k) and granted premarket approval to just 32 devices. The MDA does not require an FDA determination that the device is substantially equivalent to the grandfathered device.

The Depuy ASR Artificial Hip was never properly tested.
Instead of assuring the safety of the Depuy ASR Artificial Hip through clinical trials, Depuy marketed its ASR Hip without conducting any clinical trials and instead obtained FDA approval under section 510(k). In 2005, Depuy submitted a section 510(k) premarket notification of intent to market the Depuy ASR Hip.
By representing to the FDA that the Depuy ASR Hip’s design was “substantially equivalent” to other hip products on the market, Depuy was able to avoid the important safety review required for premarket approval under FDA regulation including clinical trials.
In August 2005, the FDA approved the Depuy ASR Artificial Hip for sale by means of the 510(k) process; thus, the FDA did not require the Depuy ASR Hip to undergo clinical trials. This turned out to be a huge mistake.
The 510(k) notification for the Depuy ASR Hip included only Depuy’s assertion that it “believes the Depuy ASR Modular Acetabular Cup System to be substantially equivalent…based upon the similarities in design, material composition, and intended use/indication for use” to devices that themselves had never been reviewed for safety and effectiveness. That is to say, the ASR Hip was approved because it appeared to be similar to other products already on the market.
Importantly, unlike the premarket approval process, the 510(k) notification process does not call for examination or testing of a device’s safety and effectiveness. A finding of “substantial equivalence” is not equivalent to a finding of the device’s actual safety and effectiveness. This is a very important distinction.
The FDA’s letter to Depuy, dated August 25, 2005, says nothing about the safety and effectiveness of the ASR Hip and finds only that the device was “substantially equivalent to devices introduced into interstate commerce prior to May 28, 1976,” and concludes by stating that the agency’s determination of substantial equivalence “does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies.”
The FDA’s finding of “substantial equivalence,” therefore, had nothing to do with reviewing the ASR Hip’s safety effectiveness, but rather only a vague determination of equivalence to devices which had not been studied for safety and effectiveness.
Essentially, no one, neither Depuy nor the FDA, did the hard work to make sure that the Depuy ASR Hip was safe for the public.

In the next post we will look at the ASR surgical technique and the metal-on-metal design of the Depuy ASR Hip.


Note:  The information in these articles was compiled from many sources over several years.  It must be noted that Depuy, Inc., and Johnson & Johnson have not and would not concede every fact listed herein.  Thus, some of these facts may still remain “in dispute.”