Arthritis is a condition affecting the joints, causing pain and inflammation. It is relatively common and can affect people of all ages, however, it is most common in people over the age of 60. Arthritis may affect one or several joints and often affects the weight-bearing joints, such as knees and hips. There are over 100 kinds of arthritis and it is a progressive disease, meaning it cannot be cured and may worsen over time. Osteoarthritis is the most common form of arthritis and is caused by stress on the joints.
The knee is the largest joint in the body and is vital for movement. It connects the femur (thigh bone) and tibia (shin bone) and is covered with the patella (knee cap). The tibia also has a smaller bone running beside it called the fibula. The joint is stabilised by tendons, ligaments and muscles. Knee osteoarthritis occurs when the firm, rubbery tissue that coats the knee joint known as cartilage becomes worn away. Cartilage enables the smooth movement of the knee as well as providing a protective cushion to prevent the bones from rubbing together. Cartilage can repair itself to some extent, but it does not regenerate once lost. One of the first signs of osteoarthritis is often stiffness or pain in the knee joint.
Cartilage layers in the knees aid movement and provide shock-absorption. The layers can become damaged from trauma, repeat movement or just everyday “wear and tear”, which is why osteoarthritis is more common in older people. There are several risk factors for knee osteoarthritis including:
- Occupation: work that is repetitive or requires strenuous movement, like lifting or climbing stairs, or is very physical.
- Obesity: from increased pressure on the load-bearing joints, particularly the knees.
- Bone deformation or injury: knee deformities, such as bowed legs (genu varum) or injuries, can cause uneven pressure on the knee.
- Age & gender: people who are over 50 or female, especially post-menopausal.
- Family history: those with a family history of osteoarthritis.
- Athletics: some exercises, especially long-distance running and tennis, can increase the risk of osteoarthritis, but it’s more linked to injury rather than the activity itself.
Osteoarthritis symptoms tend to happen gradually but can occur suddenly for some. Symptoms can range in severity and may be affected by factors such as the time of day or activity. Often, the early signs will be swelling and/or pain, particularly after activity. Some people may feel like their knee is “unstable” or “giving way” at times. Generally, symptoms may include:
- Pain: pain may be worse during/after long walks or stairs. If advanced, it can also occur at rest or while sleeping.
- Instability: the knee may feel like it’s “unstable” or “giving way”.
- Stiffness: it may be worse in the morning or after prolonged sitting. Gentle movement may help, but if severe, even short walks can be painful.
- Swelling: excess fluid in the knee joint may cause swelling.
- Warmth: the knee joint can become inflamed and warm to the touch.
- Mobility: getting out of chairs or cars can be difficult and mobility may be reduced.
- Sensations: “grating” or “scraping” feelings upon moving.
- Noises: “creaking” or “grinding” sound on movement, especially squatting. Healthy knees can make sounds too.
General osteoarthritis symptoms, such as bone spurs (osteophytes), can develop as a result of swelling. Progressive cartilage loss can lead to breakages and, in severe cases, the bones rubbing together, which can cause distortion. Patients with advanced osteoarthritis can be at higher risk of falls.
Diagnosis will start with a physical examination and questions about your medical history and symptoms. It will be important to find out how you move the knee and if any activities or movements cause more pain than others. Your knee will likely be checked for swelling.
To assess your knee thoroughly, it is often necessary to do other tests alongside the physical exam. An x-ray is a painless scan that looks at your bones and cartilage and the space between them. It can help the specialist see how advanced the osteoarthritis is and the amount of wear in the joint. Additional tests, such as an MRI (magnetic resonance imaging) scan, may be done to look at the soft tissues and cartilage. Tests for conditions like septic arthritis, which is caused by a bacterial infection, may require a blood test and antibiotics.
Treatment for knee osteoarthritis focuses on pain relief and optimising mobility.
- Painkillers or anti-inflammatories: these can be bought over the counter but, if needed on a long-term basis, should be discussed with a doctor.
- Corticosteroids: cortisone-like medicines used to provide relief for inflammation.
- Hyaluronic acid (viscosupplements): artificial synovial fluid, which may preserve cartilage.
- Glucosamine or chondroitin sulphate supplements: containing natural components of cartilage, these supplements may be suggested to help preserve cartilage. Their effectiveness has not been proven in studies, but some patients find they are helpful.
- Weight loss: to reduce pressure on the knee.
- Walking aids / assistive devices: a cane or walking stick held in the opposite hand of the affected knee could reduce pressure and encourage safer mobility.
- Physiotherapy: to support life-style modifications and possibly low-impact exercise to improve strength and/or flexibility, such as swimming, cycling and Tai Chi.
- Diet: some foods like those rich in Omega-3, may reduce inflammation or even the signs of arthritis.
- Rest: getting plenty of sleep and rest may help the body recover from stress.
If more advanced, surgery to preserve the function of the knee or replace it may be the only option.
There are several procedures which may help either preserve the function of the knee or, if needed, replace it entirely. They are typically for patients with more advanced symptoms rather than early stages of osteoarthritis.
- Knee Arthroscopy: A kind of keyhole surgery where instruments are passed into the knee joint to both examine and treat it. After examination with a tiny camera, damaged tissue and cartilage may be removed. An arthroscopy may not relieve pain and stiffness for patients with knee osteoarthritis. Learn More
- Knee Osteotomy: An osteotomy is a procedure for people with arthritis who need the bones moved to a better position to “unload” uneven weight distribution. This can relieve pain, help to preserve function and delay a total knee replacement for those suitable. It can be performed on the tibia, known as a high tibial osteotomy, or the femur - femoral osteotomy. Misalignment is corrected by either removing or replacing (grafting) a wedge of bone. Osteotomies typically last for 10 years, then will often need further surgery, usually a knee replacement. For these reasons, this procedure is suitable for a limited group of patients, typically excluding those who are older or with advanced arthritis or joint deformity. Learn More
- Knee Resurfacing (Partial Knee Replacement): Knee resurfacing or partial knee replacements replace only damaged tissue. Implants are used to either replace sections of bone or re-coat surfaces using special metal and plastic. As well as being a smaller operation than the total knee replacement, the post-operative knee function may be better as natural tissue is retained. This operation is ideal for patients with limited arthritic deterioration and typically lasts 10 to 12 years. Learn More
- Total Knee Replacement: A total knee replacement is a procedure that removes the damaged parts of the knee bone and cartilage entirely and replaces them artificial joints called “prostheses”. These are measured to fit and made of plastic and metal. Both the top of the shinbone and the bottom of the femur are removed and sometimes the back of the kneecap is resurfaced. Knee replacements typically last around 12 years. Learn More
- Stem Cell Cartilage Repair: This pain-relieving procedure uses the body’s own regenerative cells by extracting them from fat or bone marrow and re-injecting them to stimulate repair. Advantages of this treatment are its wide-ranging suitability and that it may postpone the need for a knee replacement. It may also be an option for patients who are not medically fit for a total knee replacement but have some cartilage left.