Ouch - My Poor Knees!

My Weekly's favourite GP Dr Sarah Jarvis from TV and radio writes for you

-  Dr Sarah Jarvis

Your knee is a very sophisticated bit of engineering. There are three main bones involved in movements of your knee. The biggest is your femur, or thigh-bone. This is the upper bone in your knee joint. Your main shin bone your tibia - is the lower bone in your knee joint.

At the front of your knee is your kneecap. Around your knee are tough ligaments which help support the knee and provide strength.

The ends of your tibia and femur, which form part of your knee joint, are covered with a tough, smooth connective tissue called cartilage. The back of your kneecap is covered with the same cartilage.

This forms a smooth surface, which allows the different parts of the joint to glide over each other smoothly.

Your knee joint contains slippery fluid called synovial fluid which also helps lubricate the surfaces so they move smoothly. You also have two C-shaped discs of cartilage inside each knee joint. These act as shock absorbers, reducing the pressure on your knees when you step on hard surfaces.

The most common cause of knee pain as you get older is osteoarthritis. The cartilage covering the bone in your knee joint is constantly being worn down and replaced.

Over time, the speed of repair may not keep up with the speed of wearing down. When this happens, the cartilage and the ends of the bones get worn down and roughened.

Gradually, when you bend your knee, it's not like two pieces of silk gliding smoothly, but more like two pieces of sandpaper grinding over each other.

The result is pain especially when you get up in the morning and stiffness in your knee.