O.K. - thanks for the additional information.
The most common cause of knee pain, if there was no potential of injury, is probably arthritis in this case. This will involve knee pain, stiffness, and both of these can be worse in the morning or after prolonged immobility, and they can get better with movement. The knee can also swell, but generally the "swelling" is mild.
If you could have twisted the knee, or overworked it somehow, you could have also irritated or injured the menisci (you have two meniscus in your knee). These are cartilage pads that can become injured, and this will lead to substantial swelling on the front/side of knee. There are also ligaments there, and if the knee feels unstable then these might be involved.
Finally, the blood vessels (veins and arteries) in your legs can develop problems as well, which can lead to inflammation (phlebitis), clotting (thrombosis), and arterial disease. These won't cause problems, generally, specific to the knee, however, but can affect the lower leg as a whole if your symptoms also involve the entire lower extremity.
Arthritis can respond to medications, meniscal tear really generally requires surgery, and the arterial and venous disorders can require a number of different types of treatment. I would recommend that you make an appointment with your physician, and if these symptoms are bad, or if they don't get better or they get worse, then I would be seen sooner rather than later. A clot in the leg can be a dangerous thing, but again, this generally won't produce symptoms specific to the knee.
I hope this helps. Please let me know if you have any further questions - I'm more than happy to try and help.
Take care - Dr. Fay
Edited by jcfay on August 18 2006 at 11:41 AM
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