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Metal on Metal Hip Replacement Update
The Saunders & Walker Analysis of the Official FDA Action of May 6, 2011 Ordering Investigation of Metal on Metal Hip Replacements is Provided Below.
Please Contact Us if You have any questions or additional information you think we should know about.
ABOUT FDA'S RECENT 522 ORDERS On May 6, 2011 FDA issued 145 orders for postmarket surveillance (PS) studies regarding metal-on-metal hip systems.
What is postmarket surveillance?
Postmarket surveillance means the active, systematic, scientifically valid collection, analysis and interpretation of data or other information about a marketed device to identify potential safety or effectiveness issues.
What devices can be cited in a 522 order?
Section 522 of the Food Drug and Cosmetic Act empowers FDA to order post-market studies for Class II and III products that are life-sustaining or life-supporting; are implanted in the body for more than a year; have significant use in pediatric populations; or whose failure would likely lead to serious health consequences.
What prompts the FDA to issue a 522 order?
Put simply, postmarket surveillance addresses an important unanswered question about a marketed medical device. Historically FDA has not enforced active PS requirements, but the agency has signaled this practice will change. In this case, FDA seeks to better understand metal-on-metal hip systems and their safety profiles, including information related to adverse events that may be associated with increased levels of cobalt and chromium in the bloodstream resulting from device wear.
Why metal-on-metal hip systems?
Though Class III devices, metal-on-metal total hip systems gained entry to the marketplace via the less rigorous 510k process . With less clinical data requirements, problems are more likely to emerge after such "grandfathered" devices have been cleared to market. Case reports in the medical literature have suggested the potential for systemic effects of elevated metal ion levels, including cardiomyopathy, thyroid dysfunction, and neurological changes. Also, metal-on-metal hip systems meet the criteria for PS under section 522 because they are class III devices intended to be implanted in the body for more than one year; and, FDA adds, that the failure of these hip systems "would be reasonably likely to cause pain, dislocation, or device loosening, leading to revision (any secondary surgical procedure), which would meet the definition of 'serious adverse health consequences.'"
Does FDA define the postmarket surveillance plan?
Although ordered by FDA, PS plans are developed by industry, but are subject to FDA approval. However, FDA has listed the questions that manufacturers must address in their PS plans:
- What are the adverse events observed in patients with Metal-on-Metal (MoM) total hip replacement (THR) systems seen within patients included in your study? What are the rates of expected (included in labeling) and unexpected adverse events with MoM THR? Do these rates vary across time since initial implant?
- What are the baseline serum and whole blood levels of chromium, and serum or whole blood levels of cobalt in patients prior to THR? What are the patient population's average levels of chromium in serum and whole blood and cobalt in serum or whole blood for each year for a minimum of eight years (or length of time on market) post-implant? Do these average levels increase over a minimum of the first eight years (or length of time on market) post-implant?
- What are the reasons for revision? What are the patient population's average levels of chromium in serum and whole blood and cobalt in serum or whole blood at the time of revision? Is there a statistically significant difference in these levels among patients who have revisions compared with those who do not? Is there a difference in these levels at the time of initial THR compared with the levels at the time of revision?
- Among patients who do not have a revision, what is the incidence of pain or functional symptoms? Is there a difference in chromium or cobalt levels among patients who have pain, functional symptoms or adverse events compared with those who do not exhibit these symptoms?
- Among patients who do not have a revision, what is the incidence of adverse local tissue reaction as measured by patient physical examination and imaging? Is there a difference in chromium or cobalt levels among patients who have an adverse local tissue reaction compared with those who do not? What proportion of patients with an adverse local tissue reaction have a revision within one year?
- How do differences in revisions, pain or functional symptoms, and adverse local tissue reactions vary across the time since initial implant?
3. What demographics or patient selection criteria are associated with higher metal ion concentrations? What demographics or patient selection criteria are associated with higher risk of revision?
4. What are the modes and causes of failure based on analysis of all of your reasonably available explanted retrieved devices?
What happens after the manufacturer receives the 522 order?
- The device manufacturer has 30 days to submit the PS plan, and the FDA has 60 days to review the plan. An FDA order for a Section 522 study carries substantial force. Unlike with PMA post-approval studies, failure to complete a 522 study constitutes device misbranding, and can result in civil money penalties, product seizure or prosecution.
- Who received 522 orders regarding metal-on-metal hip systems? FDA sent 145 orders to several companies. Many devices date back to the early '80s and are no longer marketed. Some of the companies no longer market hip prosthesis, while others have been acquired or dissolved.
The entities include: Advanced Bioresearch Association, a regulatory affairs firm consulting with medical device and pharmaceutical companies American Ortomed Corporation, now dissolved Biomet Inc., makers of the M2a-Magnum™ System Large Metal Articulation (Total MOM Hip) and ReCap (Resurfacing Femoral Head , not MOM system), and others no longer marketed C.R. Bard Inc., no current MOM system DePuy Orthopaedics, Inc., a Johnson & Johnson company, makers of ASR (Total Hip, Resurfacing, Recalled); Pinnacle Metal-on-Metal (Total Hip with Ultamet Insert), and others no longer marketed. Downs Surgical Ltd., no current MOM system Encore Medical, now DJO Surgical, makers of metal-on-metal liners for use with FMP acetabular system, and others no longer marketed Endomedics, Inc., no current MOM system Implantology Corporation, no current MOM system Joint Medical Products Corporation, acquired by Johnson & Johnson April 1, 1995 Link America, Inc., no current MOM system Med-Tek Corporation, no current MOM system Orthopaedic Device Corporation, no current MOM system Orthopaedic Manufacturing Company, no current MOM system Osteotechnology, Inc., no current MOM system Pfizer, Inc., no current MOM system Stryker Orthopaedics for Howmedica Osteonics Corp., markets the Cormet Resurfacing System in the US; MITCH PER Mini Hip (resurfacing, not marketed in US) and others no longer marketed Synergy Orthopaedics Intl., Inc., no current MOM system Techmedica, Inc., no current MOM system Turnkey Intergration USA, Inc., no current MOM system Waldemar Link GMBH & Co. KG, no current MOM system Wright Medical Technology, Inc., DYNASTY® Acetabular Cup System with A-CLASS® Metal-on-Metal; Conserve (Partial Resurfacing); Conserve Plus (Total Resurfacing) and others no longer marketed
Zimmer Spine, Inc., (Zimmer), Durom/Metasul (Total Hip, Recalled) and others no longer marketed
What are the revision rates for currently marketed metal-on-metal systems?
The Australian Orthopaedic Association Joint Replacement Registry reports revision rates for the following metal-on-metal systems with femoral head sizes greater than 32 mm: DePuy ASR: 7.8 at five years (total hip, recalled in US) DePuy Pinnacle with Ultamet metal insert (total hip): 3.5 (with Articul/Eze head) and 3.8 (with S-Rom head) at five years Smith & Nephew Birmingham Hip with BHR and R3, resurfacing: 4.9 at five years (with BHR head) at five years and 2.4 (with R3 head) at one year ESKA Bionik (resurfacing, not sold in US): 8.0 at three years Corin Medical Cormet, resurfacing: 7.1 at five years IO International Orthopaedics ICON (total hip and resurfacing, not sold in US): 6.5 at three years Biomet M2a with M2a liner (total hip) or Recap (resurfacing): 4.0 (with M2a liner) at three years and 2.2 (with Recap) at three years Zimmer Durom (total hip, recalled in US): 4.6 at five years Stryker Mitch TRH (resurfacing, not marketed in US): 1.5 at one year
Data were not reported for the following systems: Metal/Metal CoCr acetabular liners and femoral heads, and FMP™ acetabular system with metal-on-metal liners, by DJO Surgical, formerly Encore Orthopedics ADEPT (resurfacing) by Finsburgy Orthopaedics Ltd., UK CONSERVE (partial resurfacing) and CONSERVE PLUS (total resurfacing) by Wright Medical Technology
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