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Medical Device Recall Case Study

The objective of this lecture is to examine one of the many medical device recalls that have occurred over the years. Most have resulted in disastrous consequences both financially and medical complications for the patient(s).

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Vitek TMJ Implants

First introduced in the device in 1983 when it received FDA approval after deemed to be “substantially equivalent” to Dow Corning’s Silastic Disc Implant.

By 1986, several surgeons reported catastrophic biomechanical failure of the device, leading to bone resorption and pain. From 1986-1991 a failure rate of 10 to 25 percent was reported. Then by 1992, the success rate was less than 20 percent.

The Vitek Proplast Temporomandibular Joint Interpositional Implant

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Vitek TMJ Implants

In response to the vast number of device failures, the FDA revoked federal approval and a wide device recall was initiated. Several class action lawsuits (in different jurisdictions) were then filed, some of them still ongoing (Canadian class action suit was initiated in 1999). As a result, the company Vitek was forced into bankruptcy.

This disaster has provoked many questions into how and why this happened (along with who was actually responsible).

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Temporomandibular Joint (TMJ)

The TMJ is the major joint in the skull involved with the jaw. There are two TMJs, one on either side, which work in unison.

The unique feature of the TMJ is the articular disc. The disc is composed of fibrocartilage positioned between the two articulating bones of the joint. The disc allows for both rotational (opening-closing) and translational (sliding forward-backward) movements.

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Temporomandibular Joint (TMJ)

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TMJ Disorders

Temporomandibular joint disorder, or TMJ syndrome, is an umbrella of disorders that cover acute or chronic inflammation of the temporomandibular joint. Causes include: trauma, disease, wear due to aging, or habits.

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TMJ Disorders

The disorder and resultant dysfunction can result in: Pain (facial muscles, TMJ, shoulders, ear pain/ringing) Face and mouth swelling, trouble swallowing Chronic headaches, dizziness, and/or nausea Joint impairment (locking, failure to open, problem with teeth

lining up)

Because the disorder transcends the boundaries between several health-care disciplines (dentistry, neurology, etc.) there have been several different treatment approaches.

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History of TMJ Implants

Since the mid-1960’s, professionals have been using various materials to replace all or part of the TMJ.

Sometimes, the surgeons replace only the disc with what is called an interpositional implant (IPI). In other instances, the condyle (the head of the mandible), fossa (socket of the jaw joint), or both, are replaced with prosthetic devices.

The total number of implant recipients is currently unknown; however, a conservative estimate would be 150,000 patients in the USA alone have received TMJ implants.

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History of TMJ Implants

Most biomaterials for TMJ reconstruction were introduced before the 1974 Medical Devices Amendment Act was passed. This Act required manufacturers to provide evidence that their devices were safe and effective.

The TMJ implants that were first marketed after 1974 could be allowed on the market without testing, because of the “substantially equivalent” clause. Thus, if the manufacturer could prove that the device was “substantially equivalent” to a pre-Amendment device, the device in question would receive approval without any further evidence of effectiveness or safety.

Two products that have been widely used as disc replacements for torn and/or displaced TMJ discs are Dow Corning's Silastic and Vitek's Proplast-Teflon.

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Dow Corning – Silastic IPI

Silastic implants appeared in several forms. The first, introduced in the mid-1960’s, was a block of Silastic (silicone rubber) carved to shape. Another was Silastic HP Sheeting which was reinforced with Dacron.

Short-term studies in the early 1970’s looked good. However, reports after 1-5 years showed substantial problems, including: ankylosis (joint stiffening), arthritis, and lymph node swelling.

Several studies reported fragmentation, perforation, and deterioration of the (Silastic) material. Others stated, that silicone may not be a totally inert material and that its biomechanical properties are not ideal for use in the TMJ. By the end of the 1980’s, enough failures had occurred for some researchers to call for strict limits on the use of Silastic. Finally, after 20 years of use, it was decided that Silastic wasn't appropriate for long-term use and was discontinued to be marketed for TMJ implants.

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Vitek – Proplast-Teflon IPI

In the 1970’s, Vitek developed and sold Proplast Sheeting – a Teflon FEP film laminated to a porous composite material made from polytetrafluoroethylene (PTFE) and carbon. The implant was modified in the early 1980’s, and Teflon film was then laminated to PTFE and aluminum oxide. These implants, usually no larger than a thumbnail, were manufactured individually or custom cut from sheets in the operating room by the surgeon, and then sutured to the fossa or condyle.

As with the Silastic implants, early reports claimed success, and in 1983, the FDA allowed Vitek to market a pre-cut disc as they claimed the device was “substantially equivalent” to Dow Corning's Silastic disc, marketed years earlier.

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Vitek – Proplast-Teflon IPI

At the 1986 meeting of the American Association of Oral and Maxillofacial Surgeons, several surgeons reported catastrophic biomechanical failure of the IPI that caused a giant cell reaction, leading to bone resorption (osteolysis) and pain. By 1992, a success rate of less than 20 percent was being reported.

Only after reports of failure began appearing in 1984, were animal studies conducted on dogs. The results were catastrophic, according to a 1990 deposition of a Vitek consultant in a court case against Vitek. After just a few months, the Teflon layer was “completely worn”, and Teflon particles had triggered bone erosion.

In 1990, due to increasing reports of implant failure, the FDA recalled Vitek's IPIs. Several months later, Vitek declared bankruptcy due to rising litigation costs. However, Vitek continued to market their TMJ implants until eventually the FDA seized all products from Vitek as well as its subsidiaries.

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Reasons for Device Failure

There are many potential facts that have been implicated for the disastrous failures of the Vitek Proplast-Teflon IPI’s. The two major reasons were:

Lack of background research»Teflon was abandoned as a bearing surface in total hip

replacements from research conducted in the 1960’s»Teflon wear particles were observed to elicit an

inflammatory response leading to severe osteolysis

Lack of product validation testing»Manufacturer relied on “substantial equivalence” to a

prior device that was in use prior to regulatory standards put into effect

»No animal studies were ever initiated

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Response from the FDA

The FDA was informed of adverse-problems as early as 1986. However, because of a mix-up with their Medical Device Report program, these reports ended up being dismissed. By 1988, they had received information from experts that the Vitek implants were failing and needed to be explanted, and that patients with explanted devices were worse off than they had been before treatment. Problems included excruciating pain and the degeneration of parts of the skull.

At an April 1989 meeting of the FDA Dental Products Panel, the Panel did not make a recommendation regarding the classification of the glenoid fossa or the mandibular condyle implants. Only at the February 1993 meeting, did the FDA Dental Products Panel finally recommended that these devices be classified as Class III (devices that support/sustain human life or of substantial importance in preventing impairment of human health).

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Lessons Learned?

Several recommendations have been implemented as a result of the Vitek TMJ Implants:

• FDA to develop a system whereby scientific expertise is solicited from academic societies, industry, and federal agencies

• FDA to develop a complaint registry to allow for cross-analysis with the professional and the manufacturer

• Establishment of an implant database and retrieval system independent of the FDA