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Dental Products Panel Meeting - August 22, 2002

Issue: Review of a Premarket Approval Application for the Walter Lorenz Total Temporomandibular Joint Replacement System
Sponsor: Biomet, Incorporated

A meeting of the Dental Products Panel was held on August 22, 2002. The topic of the meeting was a premarket approval application (PMA) submitted by Biomet, Inc. for the Walter Lorenz Total Temporomandibular Joint Replacement System (P020016). The Walter Lorenz Total Temporomandibular Joint Replacement System is implanted in the jaw to functionally reconstruct a diseased and/or damaged temporomandibular joint. The Total TMJ Replacement System is a two component system comprised of mandibular condyle and glenoid fossa components.

The Open Public Hearing was the first item on the agenda following opening remarks. No one requested to speak during Open Public Hearing. The sponsor’s presentation began with an overview of the company followed by a description of the device and its various components and designs. The sponsor’s engineering representative then discussed the mechanical testing protocols and test results provided in the PMA. The sponsor’s clinical investigator then introduced the clinical portion of the sponsor’s presentation by providing a summary of the clinical treatment plan for these patients and describing the surgical procedure used to implant the device. Sponsor presenters then provided an overview of their clinical study, including a description of the study design, patient demographics, clinical endpoints, success criteria, statistical plan, clinical results, and adverse events. The sponsor reported successful clinical results, showing significant improvements for the three primary efficacy endpoints of jaw pain intensity, interference with eating, and maximal incisal opening that exceeded the success criteria established for each of these endpoints. They explained that the adverse event rate was high, but that most of the events were not device related but were related to pre-existing conditions, chronic problems, or prior history. The sponsor revealed that many of the patients for which adverse events were reported met the patient success criteria. The sponsor also stated that they found the adverse event rate to be acceptable given the patient population. The sponsor concluded that the study shows that the device results in patient improvement.

Following the sponsor’s presentation there were a number of questions from the panel members and consultants. Most of the questions focused on the following issues: 1) clarification of the clinical data, 2) statistical issues, 3) clarification of the types of patients treated in the clinical trial compared to the indications listed in the instructions for use, 4) engineering and material issues, 5) adverse events and device removals, 6) the study sample size and number of patients followed for the complete follow-up period, and 7) other clinical issues.

The FDA presentation reviewed the engineering data as well as the outstanding engineering concerns presently being addressed by the sponsor. The FDA clinical presentation included a brief overview of the clinical data and outlined several FDA concerns regarding the clinical study. The FDA concerns outlined in the presentation were as follows: 1) the number of patients followed for the complete follow-up time given in the study protocol and whether or not the results from a subset of patients adequately represented the expected outcomes for the total study group at 3 years, 2) the potential for bias because most of the patients were treated at only 2 of the study centers, 3) the adverse event rate, and 4) the use of the fossa component with and without cement.

In response to the FDA panel questions, the Panel provided the following comments. The Panel did not believe that treatment of most of the patients at only 2 of the study centers was a potential for bias in the clinical outcomes. They stated that it could actually be beneficial in terms of minimizing intercenter variability. However, the Panel did note that treatment of more patients at additional study centers would have provided data on the learning curve for use of this device and the success of the device when used by surgeons less experienced with the device and its surgical procedure. In response to the question regarding the adverse event rate, the Panel concluded that it was within an acceptable range given the patient population for which the device is used.

The Panel believed that the data for the fossa designed to be used with bone cement could be pooled with the data for the fossa components used without bone cement. However, the panel believed that the sponsor should only consider marketing the fossa component designed to be used without bone cement since that was the way the fossa was used for most of the surgeries. The Panel also expressed concern regarding the engineering testing and recommended that the sponsor provide additional engineering testing that addressed the issues of wear and creep of the polyethylene fossa component as well as the potential for crevice corrosion between the cobalt-chromium and titanium interface. The Panel also stated that the sponsor should provide additional test data regarding the use of the fossa component without cement.

In response to the last question, the Panel recommended several revisions to the labeling. They recommended that the information regarding hyperfunctional habits be moved from the Contraindication section to the Warning section. The Panel also recommended that the Indications for Use section state the indications listed that have not been evaluated through a clinical study. The Panel felt comfortable that the indication that were not evaluated as part of the study were close enough clinically to the indications that were evaluated in the study such that they could remain as part of the Indications for Use. However, they believed that it was important to identify the indications that were not studied.

The Panel felt strongly that training should be required before this device could be used by clinicians. The Panel also stated that the sponsor should complete the study and follow all patients for 3 years. Some panel members also suggested additional longer term follow-up.

The Panel unanimously voted that P020016 be found approvable with conditions.

The conditions given by the panel are outlined below:

1. The sponsor should amend the labeling as follows:
1. The labeling should provide a clearer description of hyperfunctional habits such as clenching or bruxing and this information should be addressed in a different location in the labeling (i.e., moved from the contraindication section to the warnings or precaution section).
2. The Indications for Use section should state the indications for which the device has been well tested. For indications that were not evaluated in the clinical study, the Indications for Use section should state that the device has not been adequately evaluated for these indications.
3. Information regarding the potential for foreign body reaction should be included in patient labeling and physician's information.
   
2. The sponsor should remove all references to the use of a cemented fossa and state that the device will be marketed as a non-cemented device.
   

Training

1. All surgeons implanting these devices should be required to receive didactic and hands-on training before they are able to use the device.
   

Engineering

1. The following additional in vitro and in vivo testing should be performed:
1. The sponsor should perform wear testing that simulates the temporomandibular joint
2. The sponsor should test the fossa components for possible changes in fixation stability due to creep.
3. All explants should be retrieved and studied for wear, creep, and possible corrosion due to use of dissimilar metals.
4. For explant cases, the sponsor should perform histologic examination for wear particles.
2. The sponsor should submit data from the fatigue testing of the fossa with the post removed and the fossa made without a post to FDA.
   

Clinical

1. The sponsor will seek full or partial data on all 180 cases, including retrieving VAS scores from patients at long distances and collecting full or partial post-market data. All 180 cases presently included in the study should be followed for 3 years for safety and effectiveness.

Contact: Pamela D. Scott, Executive Secretary
(301) 827-5283 Ext. 127, email pds@cdrh.fda.gov

Transcripts can be obtained from: (Written Request Only)
Neal R. Gross & company
1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005
(202) 234-4433 (voice)

or

Food and Drug Administration
Freedom of Information Staff (FOI)
5600 Fishers Lane, HFI-35
Rockville, MD 20852
(301) 827-6500 (voice) (301) 443-1726 (fax)

*Executive Summary May Be Purchased From: (Written Request Only)
Food and Drug Administration
Freedom of Information Staff (FOI)
5600 Fishers Lane, HFI-35
Rockville, MD 20852
(301) 827-6500 (voice) (301) 443-1726 (fax)

*Under normal conditions, panel summary minutes are available 60-90 days post meeting. Please time your requests accordingly.

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