Knee arthritis

Types of knee arthritis

Arthritis causes the cartilage that covers the ends of the bones in your joints to wear away. Cartilage is a flexible tissue that helps your joints move smoothly. When it wears away, your joints become inflamed, painful and stiff. 

Arthritis can affect any joint but often affects the hands, hips, knees and spine. The knee is made up of three main bones and contains two types of cartilage that are affected by knee arthritis: hyaline cartilage that covers the ends of the bones that form the knee joint and fibrous cartilage that forms two C-shaped discs called menisci. 

There are different types of arthritis that can affect the knee. The treatment you receive will depend on the type of arthritis you have. 

Osteoarthritis

Osteoarthritis is the most common cause of knee arthritis. It occurs due to wear and tear of the cartilage covering the bones in your knee joint over time. As the cartilage wears down, the bones in your knee joint rub together, which causes pain. This can also cause painful bone spurs to form that can further restrict the movement of your knee joint. 

Rheumatoid arthritis

Rheumatoid arthritis is an autoimmune condition (a condition where your body’s immune system mistakenly attacks healthy tissue) that affects the cartilage in your joints. In your knee, rheumatoid arthritis causes swelling, weakening of your knee bones, and if left untreated destruction of your knee joint.

Gout

Gout is a type of inflammatory arthritis caused by excessively high levels of uric acid in your body. Uric acid is produced by your body when it breaks down purines — a chemical involved in many processes in your cells and that is also found in certain foods. 

High levels of uric acid cause needle-shaped crystals of uric acid to build up in your joints, causing them to become inflamed, painful and swollen. Joints commonly affected include your toe joints, ankles and knees. Other symptoms include kidney stones and lumps under your skin. 

Post-traumatic arthritis

Post-traumatic arthritis develops after a knee injury, which causes excess wear and tear of your knee joint — this leads to secondary osteoarthritis. Symptoms include swelling and pain in your affected knee. 

Symptoms of knee arthritis

Knee arthritis symptoms usually worsen over time. Symptoms can come on gradually or suddenly, depending on the cause. In the later stages of knee arthritis, you may notice deformities in your knee that severely limit your ability to move your knee joint. 

Signs of arthritis in the knee include:

• Crepitus — a clicking, cracking, creaking, crunching, grating or popping sound when you move your knee joint
• Pain that is affected by the weather — pain often feels worse on cold, rainy days due to the drop in air pressure, which may affect inflamed tissue in your knee
• Redness and warmth in and around your knee — this usually occurs with gout but can occur with other types of arthritis when the inflammation is particularly bad
• Stiffness — in the later stages of knee arthritis, stiffness may become so severe that you are unable to move your knee joint
• Swelling
• Weakness in your knees ie feeling that your knees will buckle 

Symptoms of knee osteoarthritis

Knee osteoarthritis symptoms include:

• Crepitus
• Knee pain that worsens on activity and improves with rest
• Reduced range of movement of your knee — this can make it difficult to sit down, sit up and walk up and down stairs
• Stiffness — this is usually worse in the mornings or after sitting for a long time
• Swelling
• Warmth in and around your knee

Symptoms of rheumatoid arthritis of the knee

Knee rheumatoid arthritis symptoms include:

• Crepitus
• Knee discomfort, pain or tenderness that worsens when exercising, standing or walking 
• Reduced range of movement 
• Stiffness that is worse in the mornings and during cold weather — your knee joint may also become locked ie when you can’t fully bend or straighten your knee joint 
• Warmth in and around your knee
• Weakness in your knees when you bear weight on them

In addition to symptoms that specifically affect your knee, you may also notice other symptoms including:  

• A dry mouth
• Dry eyes
• Fatigue
• Inflammation in your eyes
• Loss of appetite and unintentional weight loss
• Tingling or numbness in your feet or fingers

Symptoms of gout of the knee

Knee gout symptoms include:

• Knee discomfort, pain or tenderness — you may also notice pain in your toe joints, starting in your big toe
• Redness
• Reduced range of movement
• Swelling
• Stiffness
• Warmth in and around your knee

Symptoms of post-traumatic knee arthritis

Symptoms of post-traumatic knee arthritis include:

• Crepitus
• Knee pain that worsens when bearing weight on your knee and on activity
• Redness, swelling and/or tenderness of your knee joint
• Reduced range of movement
• Warmth in and around your knee 
• Weakness in your knees ie feeling that your knees will buckle 

Causes of knee arthritis

Causes of knee osteoarthritis

Knee osteoarthritis is caused by overuse of your knee joint, which leads to wear and tear of the cartilage in your knee over time. It therefore usually occurs after age 50.

Causes of knee rheumatoid arthritis

It isn’t known what causes rheumatoid arthritis but it may be linked to your genetics or triggered by stressful or emotional events. Other risk factors include drinking a lot of coffee, eating a lot of red meat, infections, injuries and smoking.

Causes of gout of the knee

Risk factors for developing gout include: 

• Age — gout is more common in people aged 75 or over
• Family history – people whose parents or grandparents have or had gout are more likely to develop it
• Gender – gout is more common in men than women 
• Taking certain medications eg certain diuretic medications taken to treat high blood pressure
• Weight – being overweight or obese is linked to a higher risk of gout

Causes of post-traumatic knee arthritis

This is caused by an injury to your knee (eg sprain or cartilage tear) that causes excess wear and tear.

Knee arthritis diagnosis

If you have knee discomfort, pain, stiffness or tenderness, see your GP. They will ask you about your symptoms, medical history and whether you have previously injured your knee. They will also perform a physical examination of your knees — this may involve you walking so they can check your range of movement. 

Your GP will also check for signs of arthritis elsewhere in your body. Arthritis can affect other joints in your body and depending on the cause, can affect one or both of your knees. 

They may recommend tests to rule out other causes of your symptoms. This may include imaging tests, such as an X-ray to check for damage to the bones in your knee or a CT scan or MRI scan to check for damage to the soft tissues in and around your knee. 

If your GP suspects that you have rheumatoid arthritis they may recommend blood tests to detect certain proteins commonly present in people with the condition. If they suspect gout, a blood test can be used to measure your uric acid levels. 

Knee arthritis treatment

In the early stages of knee arthritis, over-the-counter painkillers, home remedies and self-care approaches are often effective to reduce your symptoms. If your arthritis becomes more severe, your doctor may recommend stronger medications and in the most severe cases, surgery.

Non-surgical treatments for knee arthritis

Home remedies

If you have arthritis, knee pain treatments you can do at home include:

• Applying heat or ice packs to your knee
• Losing excess weight — being overweight or obese puts greater strain on your knees
• Performing daily physiotherapy exercises — a physiotherapist can advise you on which exercises will improve the strength and flexibility of your knee joints
• Switching from high-impact exercises to low-impact exercises — it is important to maintain the strength and flexibility of your joints through exercises, however high-impact exercises such as running can worsen  your symptoms; instead try low-impact exercises such yoga, Pilates, walking and swimming
• Taking over-the-counter painkillers eg ibuprofen and paracetamol
• Wearing knee braces or wraps to support your knee

Some alternative therapies, such as acupuncture and balneotherapy, claim to provide relief from arthritis. However, there is no conclusive evidence to suggest these therapies work. 

Medication

If home remedies don’t ease your knee arthritis symptoms, your doctor may prescribe medication to help. All medications have side effects, which your doctor will discuss with you before you start taking them. Your doctor may prescribe: 

• Capsaicin cream — capsaicin is the active ingredient in chillies and is used in creams to provide pain relief
• Duloxetine — an antidepressant that helps reduce chronic (long-term) pain
• Risedronate — this drug helps preserve cartilage and is usually used to treat osteoarthritis 

If you have rheumatoid arthritis and these medications are not effective, your doctor may prescribe disease-modifying antirheumatic drugs (DMARDs). DMARDs affect your whole body — this is helpful when treating rheumatoid arthritis as it is an autoimmune condition and therefore can affect your whole body. DMARDs include:

• Hydroxychloroquine sulphate
• Leflunomide 
• Methotrexate 
• Mycophenolate mofetil  
• Sulfasalazine
• Tofacitinib 

For short-term pain relief, your doctor may also recommend a corticosteroid injection. 

Knee arthritis surgery

In severe cases of knee arthritis, where your knee joint is badly damaged, knee arthritis surgery may be needed. This is only recommended if all other treatments have failed to work. 

There are different surgeries depending on the extent and location of the damage to your knee. They include: 

• Arthroscopy — this is a type of keyhole surgery; using a thin, telescope-like tube with a camera on the end (an arthroscope) and small surgical tools, which are inserted into your knee through small cuts, your surgeon will find and remove damaged bone fragments and repair cartilage tears; they may also flush out your knee joint 
• Cartilage grafting — to replace lost cartilage in your knee joint, cartilage from elsewhere in your body is transplanted into your knee joint and grafted around the ends of your knee bones
• Total or partial knee replacement — your damaged knee joint is removed and replaced with an artificial (prosthetic) joint made out of plastic and/or metal

Knee arthritis recovery

Knee arthroscopy recovery

On average it takes two to six weeks to fully recover from knee arthroscopy surgery.

Knee replacement recovery

Whether you have partial or total knee replacement surgery, recovery can take up to two years. Pain and swelling will usually get better in the three months after surgery. Over the next two years, exercise will be needed to help heal scar tissue and strengthen your knee muscles.

Knee arthritis prevention

There are several things you can do to help prevent arthritis in your knees, including: 

• Eating a diet rich in omega-3 fatty acids — omega-3 fatty acids reduce inflammation and can be found in oily fish (eg salmon, mackerel and fresh (not tinned) tuna), flaxseeds, chia seeds and walnuts
• Maintaining a healthy weight — every 4.5kg of body weight translates to 13-27kg of weight when you take a step, which is why being overweight or obese puts so much extra strain on your knees and increases your risk of developing arthritis; overweight women are four times more likely to develop knee osteoarthritis than women of a healthy weight, while the risk for overweight men is five times greater than for men of a healthy weight 
• Performing regular exercise — exercise strengthens the muscles that support and stabilise your knee joint
• Practising good body mechanics — make sure you use the correct techniques when sitting, standing and lifting so that you don’t put unnecessary strain on your joints
• Taking measures to avoid injury — injury can cause post-traumatic arthritis, so make sure you wear appropriate safety kit when playing sports and learn how to exercise using the correct techniques