From Our 2010 Archives

Knee Replacements Can Fail for Various Reasons, Expert Says

FRIDAY, July 16 (HealthDay News) -- Knee implants perform well for at least 15 to 20 years in more than 95% of patients but can fail for five main reasons, a U.S. expert reports.

"A failed knee implant is usually caused by wear and tear with subsequent loosening of the implant. Other causes are infection, instability, fracture, or stiffness," Dr. Amar Ranawat, a hip and knee specialist at the Hospital for Special Surgery in New York City, said in a hospital news release.

Ranawat explained these problems in more detail in the news release:

  • When joint surfaces rub against each other, the friction wears away the surface of the implant, which can result in bone loss and loosening of the implant.
  • Infection may occur if bacteria latches onto the surfaces of metal and plastic implants.
  • For those who experience fractures around the implant, knee stability can be disrupted and revision surgery may be needed.
  • If the knee feels unstable (like it's buckling), it could be because the soft tissue that supports the knee is weak, or it could be because the implant was improperly placed.
  • When the knee joint feels stiff and the patient experiences a loss of their range of motion, the result is often pain and poor knee function.

Common signs of a failed knee implant include pain, instability, swelling and stiffness, Ranawat noted. And patients with a failed implant may require revision total knee replacement, which usually takes longer than the original knee replacement.

More than 80% of patients who undergo revision knee surgery have good to excellent results, but "up to 20% of patients may still experience pain following surgery for months or even years," Ranawat said.

-- Robert Preidt

MedicalNewsCopyright © 2010 HealthDay. All rights reserved.

SOURCE: Hospital for Special Surgery, news release, July 9, 2010

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