FRIDAY, July 16 (HealthDay News) -- Knee implants perform well
for at least 15 to 20 years in more than 95 percent 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
- 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
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 percent of patients who undergo revision knee
surgery have good to excellent results, but "up to 20 percent of
patients may still experience pain following surgery for months or
even years," Ranawat said.
The American Academy of Orthopaedic Surgeons has more about