Silent Soft Tissue Pathology & Metal-on-Metal Hip Implants

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Adverse reactions to metal debris have been reported in a large number of individuals implanted with metal-on-metal hip replacement devices. A new study focusing on this association has found a high early revision rate and an excessive number of adverse reactions to metal debris among metal-on-metal hip recipients. Patients implanted with these artificial hip products are being advised to undergo routine follow-up checkups and MRI screenings.

Metal-on-Metal Hip Implant Update 4/3/12: The U.S. Food & Drug Administration (FDA) has scheduled a two-day meeting in June to discuss the safety of metal-on-metal hip implants, which have been increasingly associated with high rates of failure. The devices have come under heavy scrutiny over the past several years due to a high number of reports of pain and swelling that have sometimes required additional revision surgeries to correct. Click here to learn more.

Free Metal-on-Metal Hip Replacement Case Evaluation: If you or a loved one has been injured by a defective metal-on-metal hip implant device, you should contact our law firm immediately. You may be entitled to compensation by filing a lawsuit and we can help.

What’s the problem?

The study, which is titled ‘Silent soft tissue pathology is common with a modern metal-on-metal hip arthroplasty: Early detection with routine metal artifact-reduction MRI scanning,‘ analyzed the clinical results of routine metal artifact-reduction MRI screening in a series of 79 metal-on-metal hip implant procedures in 68 patients. Seventy five of these procedures were scanned between 12 and 52 months after surgery. The results of the study indicated:

• 27 of 75 hips had metal debris-related abnormalities, of which five were mild, 18 moderate, and four severe;
• Eight hip replacements were revised, six of which were revised for an adverse reaction to metal debris;
• The mean Oxford hip score (OHS) for the combined group was 21;
• OHS was mean for 23 patients with no evidence of adverse reactions and 19 for those patients with detectable adverse reactions;
• Six of 12 patients with a best possible OHS of 12 showed evidence of an adverse reaction.

From these data, the study’s authors determined a high early revision rate with metal-on-metal hip arthroplasty. Adverse reactions to metal debris was common and often ‘clinically silent,’ meaning the condition can be asymptomatic, and that the patient may be unaware of the problem. Patients with metal-on-metal hip replacement devices are advised to be closely monitored and undergo routine metal artifact reduction MRI screening.

Metal-on-metal (MoM) hip replacement devices have been on the U.S. market since the 1960s. Problems with early models were largely attributed to mechanical loosening caused by poor bearing tolerances producing high friction. Over the next 30 years, improved manufacturing techniques enabled the development of a new generation of MoM devices. In the 1990’s, the Birmingham Hip Resurfacing (BHR) system was introduced to the market, and good early to medium-term results were reported. Similar products coupled with femoral stems were subsequently developed and marketed by a number of other manufacturers.

Since first being developed in the early 1980’s, magnetic resonance imaging (MRI) has proved invaluable in detecting periprosthetic tissues and in the assessment of painful MoM hip replacements. MRIs can visualize collections of fluid and inflammatory masses around the implants, which have been characterized as ‘aseptic lymphocyte-dominated vasculi- tis-associated lesions,’ ‘pseudotumors,’ and ‘adverse reactions to metal debris.’ Although these inflammatory masses have been previously observed in patients complaining of pain, there have been no comprehensive studies on the overall incidence of these lesions in an unselected series of patients. Additionally, it is not currently known whether these lesions may occur in the absence of symptoms.

The silent soft tissue pathology study found metal-debris abnormalities in one third of patients with a modern metal-on-metal hip replacement device. The finding most concerning to the researchers was that evidence of an adverse reaction to metal debris does not appear to correlate with symptoms. In fact, some of the highest levels of satisfaction were in those patients with the most severe side effects. A number of factors including female sex, small prosthetic head size, poor component orientation, and defective component design may contribute to adverse events. In conclusion, the study’s authors recommend “… that all patients with this implant be carefully followed up on a regular basis. We believe that routine assessment of these implants should include soft tissue imaging.”

Hip Implant Metal Poisoning

As metal-on-metal hip components rub against each other, metallic particles may be shed into the body around the implant site, resulting in a condition known as metallosis. Complications arising from metallosis may include:

• tissue damage
• inflammatory reactions
• bone loss
• genetic damage
• aseptic fibrosis
• local necrosis

In addition to the risk of metallosis, a number of other problems with metal-on-metal hip systems have been identified which have resulted in devastating pain and additional surgeries. Many individuals who have received metal-on-metal hip implant devices have reportedly suffered:

• unexplained hip pain more than three months after hip replacement
• loosening of their artificial hip implant
• hip replacement revision surgery

Which Metal-on-Metal Hip Implants have Been Found to be Defective?

• Johnson & Johnson hip replacement devices – ASR™ XL Acetabular System and the ASR™ Hip Resurfacing System – In August 2010, DePuy Orthopeadics issued a nationwide recall of these devices. The recall came after over 300 complaints were received describing device failure since 2008. Since then, a slew of lawsuits have been filed nationwide and many more are expected in the near future.
• Wright Profemur hip system – Problems with this type of implant could cause failure in a very short period of time. This may result in severe pain and the need for additional hip revision surgery.
• Zimmer Durom Cup – Multiple surgeons around the country have reported a higher than expected rate of failure and loosening of the Zimmer Durom Cup, often requiring painful secondary surgery. In 2008, Zimmer suspended sales of this device.

Do You Have a Metal-on-Metal Hip Implant Lawsuit?

The Product Liability and Defective Medical Device Litigation Group at our law firm is an experienced team of trial lawyers that focus on the representation of plaintiffs in metal-on-metal hip implant lawsuits. We are handling individual litigation nationwide and currently accepting new artificial hip injury cases in all 50 states.