Knee Osteoarthritis: Symptoms and Causes

Osteoarthritis is inflammation and pain that occurs when the protective cartilage in a joint is damaged or worn away. It can occur on just one side (left knee osteoarthritis or right knee osteoarthritis) or on both sides (bilateral knee osteoarthritis).

What Is Osteoarthritis of the Knee?

The ends of your bones have a layer of smooth, rubbery tissue called cartilage that protects them as they move. This protective layer is slippery and reduces friction where bones meet, allowing your joints to move easily. When the cartilage gets damaged—either from injury or from wear and tear with age—it can start to wear away, causing the bones to rub together directly. This bone-on-bone contact causes knee pain and inflammation.

Knee osteoarthritis is a degenerative knee condition that gets worse over time. There's no cure, but treatment for knee osteoarthritis can help manage the condition.

Osteoarthritis of the Knee: Symptoms

The most prominent symptoms of knee osteoarthritis are:

Knee pain, especially bone-on-bone knee pain
Stiffness of the knee, especially after sitting or lying down for a long time
Swelling in the knee
Sensation that your knee is either stuck or unstable
Cracking or grinding noise when moving the knee

What Are the Four Stages of Osteoarthritis of the Knee?

Doctors divide knee osteoarthritis into four stages to help patients better track and manage the progression of their condition over time:

Stage 1: In the first stage of knee osteoarthritis, there is only minor damage to the joint. Early knee arthritis symptoms are mild, and you may feel little to no stiffness or knee pain.
Stage 2: In mild knee osteoarthritis, the cartilage begins to show damage. Early knee arthritis symptoms develop, including noticeable pain and stiffness after a sedentary period. You begin to develop small bone spurs.
Stage 3: In moderate knee osteoarthritis, the cartilage deteriorates further and begins to erode. Symptoms worsen. Knee pain, stiffness, and swelling make it difficult to perform everyday activities like walking or climbing stairs. Bone spurs are visible on an X-ray.
Stage 4: In severe osteoarthritis of the knee, there is little to no cartilage in the knee to protect the joint. Bone spurs are pronounced, the knee joint is painful almost all the time, and symptoms significantly interfere with daily life.

Causes of Knee Osteoarthritis

The symptoms of knee osteoarthritis are caused by the deterioration of cartilage and the bones rubbing together, but what causes the cartilage to deteriorate?

Some people can damage their cartilage in accidents like sports injuries, but most osteoarthritis results from wear and tear. Your cartilage is like a shock absorber. Over time, it can wear out, either because of overuse or because your body becomes less effective at repairing and replacing it.

Risk factors for knee osteoarthritis include:

Age: The most significant risk factor for osteoarthritis is age. As we age, our bodies become less able to repair and produce cartilage. Most people will develop some osteoarthritis during their lifetime.
Weight: Carrying more weight puts more stress on your joints and can wear out cartilage faster.
Genetics: Some people have a genetic predisposition to knee osteoarthritis. If you have family members with it, you're more likely to develop it.
Activity: Moderate activity helps protect your knee from osteoarthritis, but extreme training can increase your risk. Athletes with intensive training schedules, especially those who train for high-impact sports that are hard on the knee, may be at higher risk of osteoarthritis.
Injuries: Traumatic injuries can damage cartilage. Repetitive motion injuries from jobs that require lots of squatting or heavy lifting can also damage the cartilage.
Other conditions: Some conditions make you more likely to develop osteoarthritis. For example, another kind of arthritis—rheumatoid arthritis—is also a risk factor for osteoarthritis. Type 2 diabetes has also been identified as a risk factor for osteoarthritis, possibly because high blood sugar can make cartilage more fragile and possibly because of systemic inflammation. Both Type 2 diabetes and osteoarthritis are associated with obesity, which may also play a role.

FAQs About Knee Osteoarthritis

What does bone-on-bone knee pain feel like?

For most people, bone-on-bone knee pain is a dull ache that worsens over time. Some people experience sharp pain, but it's less common. Sometimes, the sensation is described as being similar to a toothache but in the knee. The pain may get worse with activity, especially high-impact exercise like running. It may be accompanied by a rough grinding sensation when you move your knee.

What is the most common cause of osteoarthritis in the knee?

The most common cause of osteoarthritis in the knee is wear and tear from aging.

Can anything be done for osteoarthritis of the knee?

You can't reverse knee osteoarthritis or undo the joint damage it causes. Still, you can manage your symptoms and slow the progression of the condition through knee osteoarthritis treatments and sensible lifestyle choices.

Your doctor may recommend knee replacement surgery once your condition progresses and pain from knee osteoarthritis has a higher impact on your daily life.

How does knee osteoarthritis start?

The cartilage in your knee thins due to wear and tear from aging. As you age, it gets progressively thinner until there is not enough cartilage to support healthy joint movement. When that happens, you start to experience progressive pain, stiffness, and inflammation.

Is walking good for osteoarthritis of the knee?

Exercising to strengthen the leg muscles can help give your knee more support. Low-impact exercises like walking can help you feel less stiff and painful and may slow the progression of your symptoms.

How can I stop my knee osteoarthritis fom progressing?

Maintaining a healthy lifestyle is the best way to slow the progression of knee osteoarthritis. Regular, low-impact exercise is your best defense against the disease. Eating a nutritious diet, maintaining a healthy weight, and managing related conditions like rheumatoid arthritis and diabetes can also help.

Which drinks and beverages are good for arthritis?

Arthritis can benefit from anti-inflammatory compounds and anti-oxidants, so unsweetened green tea, fruit juice, and coffee in moderation are good choices. It's also crucial to stay hydrated, so drink plenty of water throughout the day.

What should you not do with osteoarthritis?

People with knee osteoarthritis should avoid high-impact activities like running and contact sports. Repetitive motions that work the knee are also a problem. However, you should also avoid being too sedentary, as inactivity can worsen your symptoms. Find a balance between staying active and overworking your knees.

Is cracking knees a sign of arthritis?

It can be. It's normal to experience occasional noises when you move your joints. However, if the noise is persistent—or accompanied by a grinding feeling—it can be a sign of knee osteoarthritis or other knee conditions like a torn meniscus.

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