Increase In Metal-On-Metal Hip Replacement Failure Rates Causes Concern

Recent evidence suggests that the use of metal-on-metal hip replacement systems may coincide with a significant increase in adverse soft-tissue reactions. More specifically, the surgical application of DePuy Articular Surface Replacement (ASR) systems has recently become the subject of mounting criticism in the healthcare community. Both the ASR resurfacing system and the ASR total hip replacement system have become synonymous with significantly high failure rates. Subsequently, recent evidence lends weight to the long-suspected link between ASR hip replacement systems and increased cobalt toxicity.

Each ASR hip device is comprised of metallic components to promote longevity and dexterity. Unfortunately, the application of cobalt and chromium may significant harm the recipients of these devices. More importantly, these defective hip replacements may potentially wear and diminish over a period of time. The deterioration generates tiny metal shavings that have the potential to cause significant damage to the soft-tissue surrounding the surgically implanted hip replacement system. If neglected, these metal pieces may lead to the gathering of fluid in the joint and surrounding muscles that can cause severe cobalt toxicity, otherwise known as metallosis.

While cobalt is a metallic compound necessary to the proper functioning of the human body, excessive concentrations of the metal may prove to be extremely dangerous or even fatal. In the event that metal shavings accumulate within the joints, recipients of hip implants may significantly increase their risk of a number of complications. Extreme cobalt toxicity has been linked to a number of adverse side effects. The following is a list of side effects associated with cobalt toxicity:

  • Cardiomyopathy
  • Hypothyroidism
  • Neurological damage
  • Impaired senses
  • Seizures
  • Blindness
  • Headaches
  • Liver damage
  • Future hip revision surgeries

Recently, concern over the surgical application of metal-on-metal hip replacement systems has grown. In a recent report issued by the Australian National Joint Replacement Registry, ASR metal-on-metal prosthetics displayed a 6.4% failure rate after three years and a 10.9% failure rate after five years. The frequency in which these devices require revision surgery is unprecedented, considering an acceptable upper rate of failure of hip prostheses is considered to be below 1% each year.

Compounding adverse incidences, regarding the association between metal-on-metal hip replacement systems and severe cobalt toxicity, have been well documented by the National Joint Registry (NJR). In an attempt to warn the public of the accelerating failure rates of ASR total hip replacement systems, the NJR analyzed the most recent data regarding the failure rates related to metal debris.

505 DePuy ASR hip replacement systems were involved in the NJR clinical study. According to a Kaplan-Meier analysis, there was a documented failure rate of 25% at six years for the ASR resurfacing and of 48.8% for the ASR total hip replacement. Of the 257 patients tested two years after receiving the device, 67 (26.1%) showed signs of serum cobalt concentration that was greater than 7 μg/l. A number that indicates an excessive amount of the metallic compound.

The NJR has reported on numerous confirmed cases of cobalt toxicity regarding the use of metal-on-metal hip replacement system devices. One case in particular involved a 73-year-old woman who was administered to an orthopaedic clinic in order to preform a screening of the hip replacement system she had received in2006. Results of her testing indicated that she had neurological symptoms, including cognitive decline, memory difficulties and depression, which had been present for seven months after suffering from a cerebrovascular episode. Accordingly, the woman also suffered from severe headaches, anorexia and weight loss, each of which may be indications of cobalt toxicity. Her serum cobalt level was 410 nmol/L (reference range, 0–20 nmol/L) and chromium level was 240 nmol/L (reference range, 0–100 nmol/L). These high numbers have been attributed to elevated levels of chromium and cobalt found in the hip replacement system she received.

Recent studies suggest that the failure rates of DePuy ASR hip replacement systems may demonstrate a severe neglect for public safety. A growing number of complications suggest that these devices may significantly increase the risk of a recipient developing cobalt toxicity. Due to the severity of cobalt toxicity, recipients may contact a lawyer at The Senators (Ret.) Firm, LLP for a free case evaluation of their potential lawsuit.