Osteo-Arthritis - What Is It?
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Fingers: Bone enlargements in the fingertips (first joint) are common. These are called Heberden nodes. They are usually not painful. Sometimes they can develop suddenly and are painful, swollen, and red. This is known as nodal osteoarthritis and occurs in women older than 45 years. Hips - are major weight-bearing joints. Involvement of the hips may be seen more in men. Farmers, construction workers, and firefighters have been found to have an increased incidence of hip osteoarthritis. Researchers think that a heavy physical workload contributes to OA of the hip and knee. Knees - are also major weight-bearing joints. Repetitive squatting and kneeling may promote osteoarthritis. Spine - can cause bone spurs or osteophytes, which can pinch or crowd nerves and cause pain and potentially weakness in the arms or legs. |
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Also it is more likely to happen in a joint that has suffered a major injury at some time e.g. a fracture involving a joint.
To explain OA, it is useful to understand the way your joints work. A joint is where two bones meet, such as in your knee and your hip. A layer of hard tissue called cartilage covers the ends of the bones, and acts like a cushion when you put pressure on the joint. Between the two areas of cartilage is a thick liquid called synovial fluid. This fluid, produced by an outer membrane, lubricates the joint, which helps it to move easily and smoothly. Ligaments and tendons then keep your bones in place, and stop them from moving too much or dislocating.
A HEALTHY JOINT |
A OSTEOARTHRITIS JOINT |
When OA affects your joint, the cartilage becomes damaged and thin. Your body tries to repair itself, so the bone underneath becomes thicker, and changes shape. The bone at the edge of the joint sometimes begins to grow outwards, and bony spurs, or ‘osteophytes' can form. The membrane surrounding the joint can also become inflamed. The damage then often causes the onset of symptoms, especially in large joints such as the knees and hips.
There are two major kinds of disease that can attack the articular cartilage.
- Inflammatory arthritis for example rheumatoid arthritis. In this disease, the immune system wrongly perceives the articular cartilage as a foreign invader and attacks it causing a painful inflammation.
- Occurs when the articular cartilage loses its ability to repair itself and recover from micro-injuries (repeated very small injuries) and starts to degenerate. Over time the shiny slippery articular surface becomes roughened and abrasive causing pain with movement. The degeneration of the articular cartilage also causes changes to the underlying bone and these can show up under an x-ray.
It is unknown why OA occurs more in some people than others and in some joints more than others. It is a disease of other animals as well as humans and one theory for its predilection for certain joints in humans relates to the fact that we have become elevated onto two legs quite recently in evolutionary history.
Who is at risk: -
- Can develop at any age, even teenagers, but is most common with advancing age over the age of 45.
- Is more common in women and less common in black and Asian populations.
- By the age of 65, around 50% of people have OA in one or more of their joints, and around 10% have some disability caused by it.
- More likely to develop OA in a person who is overweight.
- Having diseases that change the normal structure and function of cartilage, such as rheumatoid arthritis, hemochromatosis, gout or pseudogout (chalky deposits of calcium crystals form in the cartilage, and cause the joint to become red, hot, and swollen).
- Having weak thigh (quadriceps) muscles, which may lead you to develop osteoarthritis in your knees.
