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Sometimes knee joint replacements fail. There can be loosening of the implant, fractures of the bone, or lingering knee pain. The implant may have to be removed and replaced with another one. Each knee joint replacement has three main parts. There's an upper piece called the femoral component. The lower half is called the tibial component. The third part is the kneecap or patellar component. What if the implant has failed and there's nothing wrong with the patellar component? Does the patellar part have to be removed and replaced, too? Doctors at four centers in Philadelphia, Baltimore, and Boston studied this question. No one really knows how long these components last, but the old saying, "If it isn't broke, don't fix it," might be good advice in these cases. The records of all patients in these centers who had a total knee revision were reviewed. Only patients whose patellar part was left untouched during the revision surgery were included. The researchers found that if the kneecap w...
Definition Kneecap dislocation occurs when the triangle-shaped bone covering the knee (patella) moves or slides out of place. The problem usually occurs toward the outside of the leg. Alternative Names Dislocation - kneecap; Patellar dislocation or instability Causes Kneecap (patella) dislocation is often seen in women. It usually occurs after a sudden change in direction when your leg is planted. This puts your kneecap under stress. Dislocation may also occur as a direct result of injury. When the kneecap is dislocated, it can slip sideways and around to the outside of the knee.
One of the first questions I sometimes hear from people who have knee pain is: Doc, do you think it is arthritis? The answer is, invariably, please tell me more about your pain. There are many causes of knee pain and arriving at an accurate diagnosis begins with a full, comprehensive medical history and physical examination. Osteoarthritis is one of the more common causes of knee pain in people over the age of 55. However, there are many other potential causes in this population of people as well. For example, knee pain can be due to:
Ø A meniscus tear
Ø A ligament tear, sprain, or strain
Ø Malalignment of the patella (knee cap) leading to pain beneath the patella
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