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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.
Human beings are well designed for many things. We have large brains for poetry and quantum mechanics; we are good long distance runners, and of course have these awesome opposable thumbs. Unfortunately, some parts are not designed very well for our 21st century lifestyles. The low back , or lumbar spine, is first on my list for sending back (or forward?) to the engineers. A close second though might be the " knee cap " or patellofemoral joint.
The "knee cap" or patella is an ovoid shaped bone whose main purpose is to act as a fulcrum that big muscle on the front of your thigh, the quadriceps. (I'll wait while you grab your high school physics book). There are plenty of folks who do not have patellae, but because this causes the quad muscle to work inefficiently, few of these folks can run or climb stairs well. The design issue with the patella is that it articulates, or rubs up against, the end of the femur bone (thus the "patellofemoral" joint). For those of us who have pa...
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