Osteoarthritis is the most common cause of knee pain. The cartilage on the ends of the femur (thigh bone) and tibia (shin bone) starts to become thin and worn causing the bones to chafe against each other. Symptoms include pain, swelling and difficulty in moving the knee, especially in the mornings. This stiffness often decreases gradually on movement. Other symptoms can include clicking from the joint or the knee suddenly locking. Eventually bone spurs can develop as the body tries to counteract the damage through the formation of new bone cells (osteophytes) but this does nothing to help the cartilage and only adds to the pain. This can eventually cause deformity of the knee.
The knee joint is a hinge joint in that it only flexes in one direction – backwards and forwards! – but it is a joint that has a wide range of movement and, like the hip joint and ankle joint, is obviously a load bearing joint. Although you might think that each knee joint takes your full weight with each step you take, the force felt by the knee is actually greater than that due to the concussion force (or shockwave) that the ground sends up your leg each time your foot hits the ground. This is true even in just walking and even if you are “light on your feet” but is even greater if you are overweight.
No wonder that any arthritic change in the knee joint causes such pain!
Whilst knee pain, stiffness and swelling are symptoms, the diagnosis of osteoarthritis of the knee is usually done by x-rays and medical assessment.