Knee Osteoarthritis: Symptoms, Causes, and Treatment

If your knee aches with activity, stiffens up after you sit, and creaks or grinds when you move it, osteoarthritis is a likely cause. It’s the most common form of knee arthritis — and while the cartilage damage can’t be undone, the pain and stiffness can usually be managed well without surgery. This guide explains what’s happening in the joint, what helps, and when it’s time to consider a procedure.

What is knee osteoarthritis?

Osteoarthritis is the “wear and tear” form of arthritis. In the knee, the smooth cartilage that caps the ends of the bones gradually thins and roughens. That cartilage normally lets the joint glide and absorbs shock, so as it wears, the bones move less smoothly, the joint can become inflamed, and bone spurs may form. The result is the familiar pattern of pain, stiffness, and grinding that tends to build slowly over years.

Symptoms of knee osteoarthritis

• Pain that worsens with activity — walking, stairs, kneeling — and eases with rest
• Stiffness after sitting a while or first thing in the morning that loosens as you move
• Swelling and a feeling of warmth in the joint
• Grinding, clicking, or a catching sensation with movement
• A knee that feels like it might buckle, and a slowly shrinking range of motion

What causes knee osteoarthritis?

The biggest factors are age and use — cartilage tends to wear over time. Extra body weight is a major, and changeable, contributor, because every pound adds several pounds of force across the knee with each step. Previous knee injuries such as an ACL tear or a meniscus injury, repetitive high-impact activity, family history, and being female all raise the risk. Often several of these overlap.

How is knee osteoarthritis diagnosed?

Diagnosis starts with your history and an exam to check the knee’s motion, swelling, alignment, and where it hurts. X-rays are the key test — they show narrowing of the joint space, bone spurs, and other changes that confirm arthritis and gauge its severity. An MRI is occasionally added to look at the cartilage, meniscus, and ligaments in detail. Getting the diagnosis right guides the treatment plan and rules out other causes of knee pain.

How is knee osteoarthritis treated?

Treatment steps up only as far as it needs to, and the large majority of people manage well without surgery.

Weight management and exercise

Losing even a modest amount of weight meaningfully lowers the load on the knee, and low-impact exercise — walking, cycling, swimming — keeps the joint moving and strengthens the muscles that support it. Counterintuitively, staying active protects the knee; complete rest tends to make it stiffer and weaker.

Physical therapy and bracing

A therapist can strengthen the muscles around the knee, improve alignment, and reduce pain. A brace or the right footwear can offload the worn part of the joint.

Medications and injections

Anti-inflammatory medicine helps many people. When pain persists, options include a corticosteroid joint injection to calm inflammation, viscosupplementation (gel injections) to lubricate the joint, and PRP therapy in appropriate cases. Which fits depends on your knee and your goals.

When is surgery considered?

Surgery becomes an option when arthritis is advanced and pain limits daily life despite months of non-surgical care. For some patients, an arthroscopic procedure addresses a specific mechanical problem; for advanced, widespread cartilage loss, knee surgery including joint replacement is highly effective at relieving pain and restoring function. The right choice depends on the severity and pattern of arthritis, your age, and your goals. The American Academy of Orthopaedic Surgeons’ patient site, OrthoInfo, is a reliable place to read more.

When should you see a doctor?

See an orthopedic specialist if knee pain and stiffness have lasted more than a few weeks, are limiting your activity, or are disturbing your sleep. Starting the right combination of weight management, exercise, and treatment early can slow the impact of arthritis and keep you moving.

Frequently asked questions

What does knee osteoarthritis feel like?

It usually feels like an ache that’s worse with activity and better with rest, along with stiffness after sitting or in the morning. Many people also notice swelling, warmth, and a grinding or catching sensation when they bend the knee.

Can knee osteoarthritis be reversed or cured?

There’s no cure that regrows lost cartilage, but the symptoms can be managed very effectively. Weight management, exercise, and injections help most people stay active and comfortable for a long time, and surgery is a reliable option if arthritis becomes advanced.

What is the best treatment for knee arthritis?

There’s no single best treatment — care is matched to your knee. Most people start with weight management, low-impact exercise, physical therapy, and anti-inflammatory medicine, adding injections if needed, and consider surgery only when those no longer control the pain.

Should I keep exercising with knee osteoarthritis?

Yes — the right exercise is one of the most effective treatments. Low-impact activity like walking, cycling, and swimming keeps the joint moving and strengthens supporting muscles. It’s high-impact, twisting, or painful activity you want to ease off, ideally with guidance from a therapist.

Do I need a knee replacement?

Not usually. Replacement is considered only for advanced arthritis that limits daily life despite non-surgical care. When it is needed, modern knee replacement is very effective at relieving pain and restoring function.

This article is for general education and is not a substitute for medical advice. Talk with a qualified clinician about your specific symptoms.