The Advent of Metal Hip Implants
As senior citizens began enjoying longer, more active lives, the necessity for artificial hip implants increased accordingly. The Metal-on-Plastic artificial hip was considered the “gold standard,” with a forty-year history of success; millions of these metal-on-plastic hips have been implanted across the globe. According to Arthroprosthetic Cobaltism: Identification of the At-Risk Patient, by Stephen Tower, MD, among the millions of patients implanted with a metal-on-plastic hip only three required revision hip surgery as a result of cobaltism. These three cases were due to bearings contaminated with ceramic abrasive debris. Despite the success of the metal-on-plastic hip implant, manufacturers begin marketing the metal-on-metal hip implant in earnest in the early 2000’s, although the first all-metal implants were used as far back as 1976. Manufacturers claimed the all-metal hip implants would stand up better to wear, possibly even lasting as long as 15-20 years.
The all-metal hip implant was aggressively marketed toward younger, more active patients who were certainly surprised and dismayed to find that the hip implant they believed to be safe was rife with problems. In fact, several of the metal-on-metal hip implants have been recalled, perhaps most notably, the Stryker ABGII, the Stryker Rejuvenate and the DePuy ASR. More than 35% of the annual 273,000 elective hip replacements performed in the United States implement a metal-on-metal bearing; estimates put the number of Americans currently implanted with a metal-on-metal bearing at over 200,000, placing these patients at a significant risk of arthroprosthetic cobaltism. Although the surgeons and the medical community are taking a second look at all-metal hip implants due to their high early failure rate, many are unaware that patients with metal-on-metal hip implants are at risk for athroprosthetic cobaltism as well.
What is Arthroprosthetic Cobaltism?
Through mid-2007, the Air Force granted 20 waivers for aviators with hip replacements. A separate study conducted on those aviation pilots who experienced unusual symptoms after being implanted with a metal-on-metal hip implant, revealed a systemic disease termed arthoprosthetic cobaltism. All metal-on-metal hip implants generate at least some level of metal ion debris, which enters into the surrounding hip tissues, or finds its way to the bloodstream. When the Stryker hip recall was issued, Stryker noted a higher-than-normal risk of fretting and corrosion at the neck/stem junction which in turn led to excess metal ion debris, the potential for developing Stryker hip metallosis, or Stryker hip blood poisoning, and total hip failure, requiring revision surgery. In the study of the aviators with all-metal hips, those who began exhibiting adverse symptoms noted the following signs of arthoprosthetic cobaltism:
· Skin rashes
· Tinnitus and hearing loss
· Groin pain upon exertion and eventual hip “creaking” sounds
· Extreme pain after any type of physical activity
· Optical issues including light flashes
· Mental issues such as mood swings, evidence of obsessive behavior, disabling anxiety, disabling irritability, low mood and loss of libido and even thoughts of suicide
Dr. Towers’ research regarding metal-on-metal hip implants showed patients experienced the following symptoms of arthroprosthetic cobaltism, many of them as early as six months after implantation of their metal hip device:
· Mental inefficiency and poor concentration
· Heart failure
· Seizures
· Headaches
· Fatigue and hypothyroidism
· Convulsions
· Weight loss
· Heart failure with tachycardia
· Muscle atrophy
Cobaltism and the Stryker Hip Recall
Following the issuance of an Urgent Field Safety Notification in April, 2012, a voluntary Stryker hip recall was issued in July. The corrosion associated with the Stryker Rejuvenate and Stryker ABGII can result in extremely high serum cobalt concentrations. Dr. Tower noted in his article that serum cobalt is measured in micrograms per liter (mcg/L); levels of 0.19 are considered normal in the human population while cobalt levels greater than one are the maximum allowable industrial cobalt exposure and levels above 5 are considered toxic. Patients with well-functioning, well-fitted metal bearings will typically have a median serum cobalt level of between 1 and 2, as normal renal function will excrete the excess cobalt when the levels are relatively low. Patients with Stryker hip metallosis, can have serum cobalt levels higher than 19, and in some cases cobalt levels higher than 100 have been found in metal-on-metal hip recipients who also suffered chronic renal disease.
What is Stryker Hip Metallosis and Stryker Hip Cobalt Poisoning?
Stryker hip metallosis occurs as the tiny metal ion particles build up in the periprosthetic soft tissues when the metal neck juncture suffers friction during periods of activity, leading to corrosion, fretting and the release of those cobalt and chromium shards. The body reacts with an autoimmune response which identifies the shards as foreign, automatically inflaming the area around the metal debris in an attempt to rid itself of the ions. Inflammatory cells are also sent to the synovial membrane, leading to synovitis which inflames the membrane to the point that the joint is unable to rotate correctly and chronic, severe pain results. Those with metal sensitivity will even more violent reactions to the cobalt and chromium ions in the body.
Unfortunately, in the case of those patients with a recalled Stryker ABGII or Stryker Rejuvenate, the body is unable to expel the metals which continue to build up each time friction releases a new round of metal ions. Stryker hip metallosis can cause severe inflammation, pain, the destruction of bone and tissue and the failure of the hip implant. Stryker hip cobalt poisoning affects the cardiovascular, gastrointestinal, renal, and neurological systems, and can cause the loss of vision and hearing, DNA disruption, reproductive disorders, the development of pseudo-tumors and mental issues such as depression, anxiety and irritability. Stryker hip blood poisoning and Stryker hip blood toxicity are more common in women, those who are small in stature and the obese as these body types place more tension on the implant, triggering the release of cobalt and chromium ions.
When a Stryker Hip Recall Lawyer Becomes Necessary
Dr. Towers’ article concludes that medical providers must be aware when hip implantees with a metal—on-metal device present with tinnitus, vertigo, visual changes, rashes, hypothyroidism, tremors, mood disorders, dementia, heart failure and peripheral neuropathy, they could be presenting with Stryker hip arthroprosthetic cobaltism. Those Stryker hip recall patients with renal failure are at a particularly high risk of developing arthroprosthetic cobaltism and should be monitored regularly for levels of cobalt. Dr. Towers notes that patients with cobalt levels greater than 7 should have a full neurological and cardiovascular workup while patients with cobalt levels greater than 20 should be advised to undergo revision surgery. Those patients affected by the Stryker hip recall who have suffered symptoms of Stryker hip blood poisoning or Stryker hip metallosis should first see their physician and have the necessary tests to measure levels of cobalt and chromium. It can be beneficial for those harmed by the Stryker Rejuvenate or Stryker ABGII to speak to a Stryker hip recall lawyer to determine what their legal options are as well.