What is Osteoarthritis?

In knee joint osteoarthritis the cartilage gets worn and bony spurs and cysts develop.

Osteoarthritis (OA, also referred to as arthrosis or ‘wear and tear arthritis’) is a degenerative condition that affects the joints. OA is common and represents one of the leading causes of disability worldwide. OA causes joint pain in around 8.5 million people in the UK.

Joints are lined with a smooth layer of cartilage, which ensures their smooth movement and provides a degree of shock absorption in weight bearing joints. When a joint develops OA the cartilage is damaged and thinned. The underlying bone is also affected. In severe OA cartilage can be completely worn away resulting in bones rubbing against each other and starting to wear away. This leads to pain and instability within the joint itself. Bone reacts to compensate by the formation of bony spurs called osteophytes. These may be a further source of pain.

What causes osteoarthritis and who gets it?

Throughout life our joints are constantly undergoing a degree of damage and repair as they are subjected to various stresses through our daily activities. Osteoarthritis develops when this process becomes faulty resulting in wearing down of the cartilage.

No one knows exactly why we develop osteoarthritis, or why some people develop it and others do not. However, a number of risk factors for the disease have been identified:

  • Age – osteoarthritis becomes more common with increasing age.
  • Genetics – although no single gene has been identified as a cause of osteoarthritis, there does appear to be some inherited tendency for the condition.
  • Gender – overall women are more likely to develop osteoarthritis than men. However this varies with different joints. Hand osteoarthritis tends to affect women much more than men, while knee osteoarthritis has a more even distribution between the sexes.
  • Obesity – osteoarthritis of weight bearing joints such as the knee are more likely to occur in obese people. This is thought to be due to the increased load on the individual joints.

Arthroscopy image showing bone-on-bone arthritis, with complete loss of cartilage from areas on both the femoral and tibial surfaces of the joint.

What are the symptoms of osteoarthritis?

The main features of OA are pain and stiffness. Stiffness tends to be worst in the morning and joints tend to loosen up within about half an hour. In contrast, pain tends to get worse as the day progresses. In severe arthritis pain persists despite taking regular pain relief medication, and often interrupts sleep at night. Some swelling may be present but this is usually not so severe as in rheumatoid arthritis. Individuals may develop tightness in the muscles and ligaments, which prevent the joints from reaching a full range of movement. In addition, deformities of joints may also develop with severe osteoarthritis. For example if you have arthritis of the knees it may become impossible for you to fully straighten the leg at the knee and you may develop valgus deformities (‘knock knees’) or varus deformities (‘bow legs’). As a result of these symptoms people experience a significant reduction in function. For example:

Decreased mobility – reduced walking distance, difficulty going up or down stairs, an increased risk of falling

Difficulties with activities of daily living – such as dressing, putting socks and shoes on, getting in and out of the bath or having sex.

Management of osteoarthritis

There is no cure for osteoarthritis, but a number of treatments can be used to help control the symptoms of the condition. Initially non-operative management should be attempted. This includes activity modification, regular exercise and physiotherapy, the use of walking aids, weight control, and medicines to control pain. Steroid injections into the may be used to reduce some of the inflammation.

Most people with osteoarthritis will not require surgery. However, osteoarthritis of a joint can become so severe that the symptoms are not controlled by conservative measures. Sometimes keyhole (arthroscopic) surgery can help. For example keyhole surgery can be useful in the knee joint, for the following purposes:

To assess the severity of arthritis, and suitability of the knee joint for further procedures including high tibial osteotomy or partial knee replacement

To shave away any loose edges, or flaps of cartilage which are catching, if the history and examination findings suggest that this is taking place.

An osteotomy is where the bone is cut and refashioned. It can sometimes be done in the knee, if only part of the joint is affected by arthritis, to shift the load onto an unaffected part of the joint. For severe arthritis where the cartilage is completely worn to leave bare bone rubbing on bare bone, joint replacements have become increasingly common. Hip and knee replacements can offer excellent pain relief from end-stage arthritis.

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