The knee joins the thigh with the leg and it makes it possible for the leg to bend and extend. It is the largest joint in the human body. Since it also the most used joint in the body, it is often affected by injuries and medical conditions.
There are many factors that can trigger knee pain. Below you will find some examples.
It occurs most of the times because of intense use of the knee joint. Those affected will experience pain in the front part of the knee. Pain will frequently grow in intensity during activities such as running, climbing stairs, squatting or sitting down for long periods of time. Running athletes are commonly affected, especially women.
There is a lubricating fluid inside the knee, produced by the bursa sacs. In case of knee injury, intense use of the joint or increased pressure, an inflammation of the sacs can occur. This condition is called bursitis.
If the knee gets injured, fluid might accumulate inside in large quantities. This condition is also called "water on the knee".
The top of the bones and the knee cap are covered in cartilage. It can sometimes occur that this cartilage is getting deteriorated or irritated
Between the bones of the thigh and the leg there is a special cartilage with the role of shock absorber. If it gets damaged, the condition is called torn meniscus.
There are four ligaments that keep together the knee joint. The medial and lateral collateral ligaments are connecting together the far end of the thigh bone and the near end of the leg bones (tibia and fibula). They are responsible for holding the bones together and not allowing them to move sideways. The cruciate ligaments are in the middle of the knee joint and they are connecting the far end of the femur with the near end of the tibia.
The knee joint is supported and allowed to move by the front muscles of the thigh (quadriceps muscles) and the back muscles of the thigh (hamstring muscles). Any damage that occurs to these muscles from various reasons will affect the functioning of the knee joint as well. When these muscles become extremely week, the knee joint might give out, resulting in a fall and additional injuries. They can also get strained by activities that cause rapid contractions or by intense use.
Knee injuries often trigger knee pain. Acute injuries can result from broken bones, ruptured ligaments, accumulation of excessive joint fluid because of infections, arthritis, or knee strain. Specific symptoms of acute injuries are intense pain and swelling.
Small injuries, like minor damages of the cartilage or tendon, or ligament injuries, are more likely to cause moderate pain and swelling, and will not affect walking or knee bending so much. Certain conditions such as patellofemoral pain syndrome, arthritis flares, bursitis, or knee strain and effusion can occur if the knee is overused. When injuries are not present, the most common causes of knee pain are deterioration over time, arthritis and painful knee caps