Knee osteoarthritis

What causes knee osteoarthritis (OA)?

All normal joints and joint tissues are constantly undergoing some form of repair because of the wear and tear that our daily activities place on them. However, in some people, it seems that this repair process becomes faulty in some way (perhaps because of severe wear and tear to the joints or a problem with the repair process) and OA develops.

A certain amount of wear and tear is normal as we age. In joints with OA, the joint cartilage (otherwise known as articular cartilage) becomes damaged and worn.

The bone tissue next to the cartilage can also be affected and bony spurs can develop around the joint edges. Those spurs are called osteophytes and we can sometime see these on X-rays.

The joints and the surrounding tissues can also become inflamed. This inflammation is called synovitis.

Development of knee osteoarthritis

Some of the many factors that may play a role in the development of OA include:

• Age: OA becomes more common with increasing age. By the age of 65 at least half of the people will have some OA in one or more of their joints.
• Autoimmune disease: such as rheumatoid arthritis.
• Previous joint damage or deformity: this may be from a previous fracture or injury around the knee joint that has caused damage to the joint surfaces.
• Obesity: knee OA is more likely to develop if you are overweight. This is because there is an increased load on the joints and a potential for more damage.
• Gender: women are more likely to develop OA than men.
• Genetics: there may be some inherited tendency for OA to develop in some people if your parents, brothers or sisters have had OA.

In the majority of people, the exact cause of OA is unknown. It is probably a combination of the above factors.

What are the symptoms of knee osteoarthritis?

• Pain, stiffness and limitation in full movement of the joint are typical. The stiffness tends to be worse first thing in the morning but tends to loosen up after half an hour or so. The pain tends to be worse while you are using the joint, however sometimes the pain can wake you at night even when the joint is being rested.
• Swelling and inflammation of the knee can sometimes occur.
• An affected joint tends to look a little larger or more knobbly than usual.
• A grating or cracking sound or sensation at your knee is fairly common.
• Weakness and muscle wasting around the knee joint can make it difficult to fully straighten the knee.
• Reduced function, such as problems with climbing stairs, walking for long distances, and kneeling. You may experience all or some of those symptoms.

Your symptoms may vary for no apparent reason with bad spells of a few weeks or months broken by better periods.

How is knee osteoarthritis diagnosed?

We usually diagnose OA based on your symptoms and the physical signs that we found when your knee was examined. There are no blood tests for osteoarthritis.

X-rays are often not needed to diagnose osteoarthritis. However, sometimes your doctor may suggest X-rays or other tests if they are uncertain about the diagnosis and want to rule out other problems.

What you can do to help yourself

There is no cure for OA. However OA may not necessarily get worse and there are many things you can do to manage the symptoms to maintain an active lifestyle.

Reduce stress on the joint

• Keep to your ideal weight. Extra weight on the joint can make symptoms worse. Even a modest weight loss can make quite a difference.
• Avoid high heels. Wear appropriate footwear with cushioned soles or insoles.
• Try not to overstress your joint by doing too much in one day. For example, spread household chores throughout the week.
• Avoid being in one position for too long when possible, to help prevent stiffness and pain. For example, keeping your knee bent for long periods while working or driving can increase your knee stiffness and pain.
• Use a walking stick if you have one. However, ensure this is used in the other hand to where the pain is. For example, if you have pain in the left knee your stick should be used in the right hand.

Regular exercise

OA in the knee can weaken the thigh muscles (quadriceps). This can increase your knee pain and you may feel as if your knee has a tendency to give way, perhaps even causing you to stumble or fall.

Regular exercise is important and one of the main things you can do to improve your symptoms. However, it is important to find the right exercise that works for you.

Generally exercises that allow you to work on your thigh muscles while not putting too much stress through your knee joint are the best type. These are termed low impact exercises. Types of low impact exercises we recommend include cycling, swimming and walking. High impact exercises such as running or jumping should be avoided.

A physiotherapist in your local hospital or health centre can give you more advice on exercise and managing with osteoarthritis. Swimming can be a very good way of exercising and keeping fit. The water supports the body's weight so that little force goes through your joints as you exercise and causes very little pain.

Leisure centres also run a variety of exercise classes that may be suitable and enjoyable. These classes can help to introduce you to exercise especially if you have not done it for quite some time.

See Waiting well exercises - including High Life Highland classes and programmes.

Other treatments

Some people find that they can also get some pain relief from using hot or cold packs. Try wrapping crushed ice in a damp towel and hold it for five to ten minutes against the part of the knee that hurts. You can do this every two to three hours. Make sure you use a damp towel between the ice and the skin to avoid an ice burn. Or you could use a heat pad or a hot water bottle with an insulated cover on it. Make sure this is not too hot and not directly touching your skin. You can apply this for 10 to 15 minutes, three to four times a day.

Medication

If you still have pain after trying the above you can speak to your doctor to discuss medication for pain relief.

Surgery

You won't necessarily need a knee replacement if you have OA of your knee. Your healthcare team will always try non-surgical measures first before suggesting a knee replacement. If your symptoms are still manageable and your pain medication is effective then you may prefer to wait and continue without surgery.

Most people who have a knee replacement are over 55. One of the reasons for this is that the earlier you have a knee replacement, the greater the chances that you’ll eventually need further surgery on the same knee, because the implant wears out and needs to be replaced again. There is also evidence that the younger patients are more likely to be unhappy with their knee replacement. This "re-do" procedure is called revision knee surgery and it is more complex than doing your knee replacement for this first time. As a result revision knee surgery comes with potentially higher risks and complications.

More information

• ​Knee problems - for those who have a new knee problem, including trauma-related knee injuries - from NHS inform
• Patellofemoral pain syndrome - from NHS inform
• Learn to stand, walk and sit with crutches - mobilising with crutches and using stairs - from NHS inform
• Osteoarthritis of the knee - from Versus Arthritis