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Stryker Rejuvenate Modular & ABG II Modular-Neck Hip Complications.

Complications of Stryker Rejuvenate & ABG II Modular-Neck Hip Stems

The Stryker Corporation’s July 2012 recall of two of its artificial hip implant systems was prompted by complications attributed to the devices’ metal components. The recalled products are the Rejuvenate and ABG II modular-neck hip stem systems. Stryker will also halt all global production and sale of the two devices.

The two hip systems lead to the same complications as metal-on-metal hip implant systems — metallosis, corrosion and a higher failure rate. There have been several recalls involving metal-on-metal hip systems.

According to the company’s recall notice, post-marketing surveillance data suggest that the recalled products may be prone to “fretting and/or corrosion at or about the modular-neck junction,” which “may lead to pain, swelling and other adverse reactions in the surrounding tissue.”

Metallosis and Other Problems

Unlike other hip implant systems that have a one-piece fixed femoral neck and stem, Stryker’s Rejuvenate and ABG II systems include several mix-and-match neck and stem components. The necks are an alloy of chromium and cobalt, and the stems are coated with titanium.

When the two metal components wear against each other in the course of normal movement, they can shed minute metallic particles into the body — the same problem seen in hip implants with metal-on-metal ball-and-socket designs. Metallosis occurs when ions of these metals leach into the soft tissue, bones or bloodstream of a hip transplant recipient. One investigation found that chromium and cobalt ions from these metals can cause damage to the lymph nodes, spleen, liver and kidneys. Other studies have suggested links to neurological and heart problems.

In the short-term, metallosis can cause necrosis, or premature death, in surrounding tissue at the implant site. Healthy pink tissue eventually becomes gray or black and dies. The longer the source of metal debris is present, the worse the soft tissue damage may be.

Some affected patients may notice the growth of lumps, or pseudotumors, under their skin. These are fluid-filled sacs, created by the body’s immune system in an attempt to isolate the toxic metals.

Cobalt is considered particularly dangerous. Effects of cobalt poisoning can include:
  • Visual impairment or blindness.
  • Cardiomyopathy (heart disease).
  • Cognitive impairment.
  • Auditory impairment of deafness.
  • Hypothyroidism.
  • Peripheral neuropathy (nerve damage).
  • Rashes.
  • Heart failure.

Osteolysis and Revision Surgery

Another complication of neck-and-stem fretting — the deterioration caused by the grinding and wearing of metal components — is a condition called osteolysis, wherein the bone at the implant site dissolves around the metal hardware, causing the implant to loosen. Symptoms of this loosening may include pain or swelling around the hip, difficulty in climbing stairs, and/or difficulty in mobility or hip flexion.

Once a hip implant loosens and fails in this way, a patient will generally need to undergo surgical intervention, including the replacement of any modular metal components. Revision surgery of femoral components is often more difficult for the physician and more traumatic for the patient than the original procedure, because there is typically less healthy tissue and bone available for the surgeon to work with. Sometimes removal of femoral components causes the femur, or thigh bone, to fracture, lengthening the period of recovery.

FDA Receives Thousands of Adverse Reports

The Food and Drug Administration (FDA) has received dozens of adverse event reportsfrom patients who required revision surgery due to metal toxicity from the two recalled Stryker modular-neck hip stem products. This likely contributed to Stryker’s decision to recall its two systems, perhaps anticipating a future FDA-mandated action.

Data from a recent FDA report suggests that hip replacement systems using the metal-on-metal ball-and-socket design are more likely to fail than other hip implant devices. In fact, most of the adverse events reported to the FDA in the past decade involved revision surgery to remove a failing metal-on-metal hip implant.

From 2000 to 2011, the agency received approximately 16,800 adverse event reports associated with such products. In 2011 alone, metal-on-metal complaints totaled 12,137, compared with 6,332 associated with other types of hip replacement systems.

Stryker Lawsuits

Over the past years, many lawsuits have been filed by patients who have suffered failed hip replacements. The Stryker Corporation has been sued due to previous defective hip implant products, and with the recent recall of its modular-neck hip stem systems, is likely going to be confronted with a rash of new filings.

Anyone who has received a Stryker hip implant and is experiencing any negative symptoms should contact his or her surgeon to check for anomalies and/or increased cobalt and chromium levels in the blood. Affected patients should also contact a reputable product liability lawyer without delay, as they may be eligible for compensatory damages for pain and suffering, medical costs and/or loss of wages.

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