Osteoarthritis is a condition of wear and tear of the smooth bearing surfaces of the knee joint. This is also known as degenerative osteoarthritis. This wear may occur primarily or secondary to trauma to the knee (traumatic osteoarthritis).

This process is similar to wear that we see in everyday surfaces like a road. Initially the breakdown occurs deep below the surfaces between the top and deep layers. As the wear process continues, the lining on the end of the bones (the articular cartilage) becomes thinner. At this stage the changes of arthritis become visible on x-ray.

Arthritis may present with pain and swelling. This may cause a restriction in activities of daily living, such as running, walking or stair climbing.

Arthritis may also cause mechanical symptoms such as locking or catching of the joint as the roughened surfaces move over each other.

As arthritis becomes more progressive, the range of movement of the joint may reduce, resulting in an inability to fully straighten or bend the knee. In addition to this, the wear may cause the knee to start to progressively become knock-kneed or bow legged.

Initially treatments may be very simple and include modification of activities, treatment with physiotherapy and painkillers and reduction in body weight to off the knee.

If symptoms persist then a number of surgical options are available and these would include:

• Arthroscopic or keyhole surgery
• Realignment surgery
• Knee replacement surgery

In addition to wear and tear arthritis, inflammatory type arthritis may also be a cause of knee pain and swelling. This includes conditions such as rheumatoid arthritis.