An NPS Medicinewise article, Monitoring for Potential Toxicity in Patients with Metal-on-Metal Hip Prostheses, discusses metal-on-metal hips, including the higher-than-normal rates of revision as well as concerns regarding the potential for metal ion toxicity. Blood toxicity monitoring is extremely important for those with a Stryker Rejuvenate or Stryker ABGII—both models involved in the Stryker hip recall in July, 2012. It is also crucial that your chosen physician have a solid understanding of the potential problems associated with your Stryker Rejuvenate or Stryker ABGII as well as the presentation of metal toxicity. In the past, most hip implants were metal-on-plastic, and these hip implants, by and large, caused few problems for recipients.
Nonetheless, manufacturers began pushing their metal-on-metal hip implants, claiming that younger, more active patients could benefit from the implants longer expected life (15-20 years). New metal-on-metal designs and modifications brought increased femoral head size, shorter tapers and a reduced neck diameter with a promise of an increased range of motion and a lower incidence of dislocation. Unfortunately, as more patients were implanted with all-metal implants, adverse reports began filtering in to the FDA regarding symptoms of Stryker hip metallosis and Stryker hip blood toxicity. It appears that as patients engage in physical activity, the metal parts of the implant device experience friction, which results in metal ion debris being released into the body. In fact, at the time of the Stryker hip recall, the company stated the risk of fretting and corrosion, leading to excess metal ion debris and a higher-than-normal risk of implant failure.
How Valid are the Concerns Regarding Long-Term Safety of Metal Hips?
Patients who undergo implantation of a metal hip device hope for a fully functioning joint which will delay the need for revision or replacement as long as possible. The shift from normal-sized to large-diameter femoral heads with metal bearing surfaces have greatly increased the need for vigilance regarding the safety of metal hips as a whole, particularly those which have already been recalled, including the Stryker ABGII and the Stryker Rejuvenate. According to the Medicinewise article, the first reports of adverse tissue reactions to metal ion debris surfaced in 2008. These reports detailed soft tissue masses in the hip area known as pseudo-tumors and thought to be a toxic reaction to excess metal ion debris, or a hypersensitivity to normal amounts of metal ions in the body. Those patients with all-metal hip implants could be exposed to cobalt and chromium particles which lead to serious symptoms of Stryker hip metallosis and Stryker cobalt poisoning.
While revision surgery can reverse many of the toxic symptoms of heavy metal exposure, some of those symptoms may be permanent. Although Stryker declined to state a specific failure rate during the Stryker hip recall, independent studies have placed that number anywhere from 12% to over 50%. Since the “normal” failure rate of ceramic or polyethylene implants is between 1-3.5%, these numbers are truly alarming. Regular Stryker hip blood toxicity monitoring can ensure the levels of cobalt and chromium are not in the dangerous range, however those patients with metal sensitivity may present with serious side effects yet test relatively low levels of metals. Conversely, some individuals may have a particularly high tolerance for cobalt and chromium, and even though their levels test high, they may not as yet have many adverse physical symptoms. Even so, any time levels of cobalt and chromium are elevated, the potential for serious health risk exists.
What Levels of Cobalt can Lead to Stryker Hip Cobalt Poisoning?
In the “normal” human body, cobalt levels are 0.19 mcg/L (micrograms per liter). Those who have suffered industrial exposure to cobalt could have levels from 1-5 mcg/L, although any level over 1mcg/L is considered excessive exposure. About half of all those with metal-on-metal hips have levels greater than 1 mcg/L, while levels above seven are frequently reported in those with all-metal hips. Cobalt levels from 1-5 mcg/L can result in myocardial and memory impairments, while levels above 7 mcg/L can result in tissue necrosis, the formation of pseudo-tumors and chronic pain for the patient. The levels of cobalt among those patients who have been advised to have hip revision surgery is frequently 19 mcg/L or greater, and patients with severe and chronic hip pain should definitely have their levels of cobalt tested. Patients with cobalt levels above 23 mcg/L can experience cognitive decline, the inability to hear high frequency sounds and vertigo.
Symptoms of Stryker Hip Metallosis and Stryker Hip Blood Poisoning
If symptoms of Stryker cobalt poisoning are ignored, or attributed to other issues, the levels of cobalt and chromium will continue to rise. In case reports detailing severe Stryker cobalt poisoning, (generally those with cobalt levels higher than 66 mcg/L) patients suffered loss of hearing, blindness, chronic and severe depression, irritability and anxiety, heart failure, seizures, tremors, myocardial fibrosis, hypothyroidism, skin rashes, reproductive disorders, the development of certain cancers, disruption of DNA, renal disorders and neurological disorders. Stryker hip metallosis occurs when the metal ions lodge in hip tissue, leading to severe inflammation, destruction and loss of tissue and bone, chronic, sometimes debilitating pain, and the failure of the implant.
When failure occurs, or the levels of cobalt have caused serious health issues, revision surgery becomes necessary. Unfortunately, revision surgery brings additional risks and a longer recovery time than the original implant surgery, and, in the case of the Stryker Rejuvenate, it can be particularly difficult to remove the stem, which is longer than normal, and planted deeply within the femoral bone. When the surgeon must remove the stem, the femur can shatter, causing short-term or even permanent patient disability.
Stryker Hip Blood Toxicity Monitoring
Stryker hip blood toxicity monitoring is crucial for the health of the patient with a metal-on-metal Stryker Rejuvenate or Stryker ABGII. As detailed in the Medicinewise article, the following monitoring is recommended for those with a metal hip implant:
· Annual assessment for pain, decrease in joint function or loss of visual or auditory acuity
· Annual assessment for serum cobalt and chromium concentrations; every three months thereafter for those with elevated levels of these metals
· Physician must be hyper-vigilant in looking for signs of cobaltism among patients with poor renal function
· Physician must consider the effects of cobalt and chromium toxicity in the context of the individual, taking into consideration that patient’s particular risks and stated symptoms
· Patients who are asymptomatic should nonetheless have a full workup at least annually
· Among patients with high metal ion levels, physician must determine whether there are other reasons to explain high cobalt readings such as occupational exposure, renal insufficiency, inappropriate use of dietary supplements or a second metal implant in the body.
How a Stryker Hip Recall Lawyer Can Help
If you have symptoms of Stryker hip blood toxicity it is important that you speak to your physician, relaying all those symptoms, particularly pain in the hip or groin area. Your physician should order blood tests to determine levels of cobalt and chromium in your body and assess your risk for Stryker hip metallosis and Stryker hip cobalt poisoning, according the guidelines above. After taking care of your health, it can be beneficial to speak to a Stryker hip recall lawyer to determine whether your symptoms warrant a potential lawsuit against Stryker.