Doctor Group Addresses Metal-on-Metal Hip Implant Concerns

Recently, the American Academy of Orthopaedic Surgeons (AAOS) issued a statement regarding safety concerns surrounding <"">metal-on-metal hip replacements. According to a report published earlier this year in The New York Times, metal-on-metal hip implants have been used in about one-third of the approximately 250,000 hip replacements performed annually in the US. However, many of the nation’s leading orthopedic surgeons have reduced or stopped use of these devices because of concerns that they can cause severe tissue and bone damage.

In August, <"">Johnson and Johnson DePuy Orthpaedics unit issued a DePuy recall for its ASR XL Acetabular System, a metal-on-metal device. A hip implant should last for 15 years or so. However, recent data from the National Joint Registry of England and Wales showed that 1 out of every 8 patients (12%-13%) who had received the recalled devices had to undergo revision surgery within five years of receiving the DePuy ASR XL Acetabular System.

Some studies of metal-on-metal implants indicate that such devices can quickly begin to wear, creating a large amount of metallic debris that is absorbed into a patient’s body. This debris can cause inflammatory reactions that lead to pain in the groin, death of tissue in the hip joint and loss of surrounding bone among other <"">DePuy hip replacement complications. These metal particles can infiltrate organs and tissues, and may even create large, painful cysts. The limited studies conducted so far on metal-on-metal hip implants estimate that 1 to 3 percent of implant recipients could be affected by the problem.

In April, European regulators announced they would be conducting a review of 40,000 metal-on-metal hip replacements over fears that the devices could cause non-cancerous tumors and tissue damage. At the time, officials with the United Kingdom’s Medicines and Healthcare Products Regulatory Agency (MHRA) said anyone considered at risk would be given tests to establish whether there are high levels of metal compounds in the blood.

The AAOS statement details a case report in the online American edition of the Journal of Bone and Joint Surgery (JBJS) regarding two patients who received metal-on-metal total hip replacements experienced adverse events. The report outlines the adverse effects – including timelines and descriptions of the problems they experienced until the implants were removed at 47 and 40 months, respectively. After the revision surgeries, the symptoms improved. Both patients were fit, healthy 49-year old males. Their experience reports that cobalt toxicity developed within their bodies after the all-metal devices were implanted.

The case report states that at present, at least six reports of cobalt toxicity have been related to arthroplasty implants, although the two in this report are the only ones that occurred in patients with metal-on-metal hip replacements. It also notes that a larger group study will be required to define the prevalence and spectrum of cobalt poisoning due to hip arthroplasty.

“This information is not meant to instill any type of fear in our patients,” Chitranjan S. Ranawat, MD, president of the Hip Society and an orthopaedic surgeon in New York, said in the AAOS statement “However, we want to elevate patient awareness about metal-on-metal hip replacements. We suggest that any patient who received a metal-on-metal hip inform all medical care givers about their joint replacement device and pay attention to post-operative pain.”

The AAOS statement advises hip replacement patients to speak to their doctor or surgeon if they notice new pains or medical concerns.

“In general, a patient should be relatively pain-free three months after any hip replacement surgery,” stated Joshua Jacobs, MD, spokesperson for the AAOS and an orthopaedic surgeon and researcher in Chicago, Ill. “Any new pain or increase in pain at that point should be promptly communicated to your surgeon, as it may indicate a complication.”

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