Why Does My Knee Hurt?

Joints are the locations in your body where two bones meet. Movement of these bones against each other is what permits our bodies to move. Cartilage is located at end of our bones and is a smooth, slippery tissue that allows the bones to slide against one another with minimal friction. Once cartilage is damaged, it cannot heal itself and the progressive deterioration leads to a loss of cartilage and exposed bone. Because pain sensors are located in bone and not in cartilage, it is the exposed bone that results in a knee pain.

A variety of events can damage cartilage, including trauma (injury), infection, inflammation or a joint that is not properly aligned. A traumatic injury can cause an isolated defect, while malalignment tends to cause widespread damage to both sides of the joint. This is very similar to the way a car tire loses its tread when the wheels are not properly aligned.

Arthritis commonly occurs where the joints in your knee meet, known as the condyles (the end of your thigh bone) or in the area behind the kneecap. If you have pain in your knee when getting up from a chair or going up and down stairs, you may have damage in your kneecap (patello femoral joint). If you have knee pain after standing or long walks then it may point to a problem in one of the condyles.

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Osteoarthritis (OA)

  • Knee_Arthritis2The most common cause of knee pain is osteoarthritis (OA), a degenerative joint disease that causes the cartilage in your joints to break down. When that layer of cartilage — which is meant to “cushion” the joints and protect the surface of the bones — is damaged or worn away, your bones grind against one another, and that grinding hurts. You can feel it climbing stairs, working in the garden, or just bending your knees to sit. It may even keep you up at night.
  • OA can damage the entire knee or be limited to just one side of the knee. If you experience pain only on one side, or compartment, of your knee, your doctor may diagnose you with unicompartmental OA.
  • If you experience knee pain under the knee cap, your doctor may diagnose you with patello-femoral OA. This is not uncommon, as studies have shown that about one out of every 10 patients over the age of 40 have patello-femoral disease.
  • The factors leading to the development and progression of OA include aging, obesity, joint injuries, and a family history of arthritis (genetics). Although there is no cure, early diagnosis and treatment are crucial in slowing or preventing more damage to your joints.

Rheumatoid Arthritis (RA)

  • In rheumatoid arthritis, the synovium (lining of the joint) becomes inflamed. This inflammation causes chemicals to be released that thicken the synovium and damage the cartilage and bone of the affected joint. This inflammation of the synovium causes knee pain and swelling.
  • The good news about rheumatoid arthritis in the knee is that there are treatments. Rheumatoid arthritis is a disease that typically worsens over the years, so it is common for treatment to involve more than one approach and to change over time. For some people, nonsurgical treatments such as lifestyle changes, medications, and walking aids help alleviate the pain. For others, replacing lost cartilage with tissue grafts may help restore normal function. And for many, knee replacement surgery may be the only long-term solution. Together, you and your doctor can determine the best treatment options for you.