Knee Osteoarthritis

Knee osteoarthritis develops as cartilage and other tissues in the knee change, causing pain, stiffness and reduced movement.

Knee osteoarthritis, also called knee arthritis or degenerative knee disease, affects the surfaces that help the knee move smoothly. Cartilage can become thinner, the joint lining may become irritated, and bone can remodel at the joint edges. These changes can make bending, standing or walking uncomfortable. Symptoms may affect one knee or both and can vary from day to day.

Knee pain is a very common presentation of knee osteoarthritis and may be worse after walking, stairs or prolonged standing. Stiffness after rest, swelling, clicking or grinding, reduced knee bend, limping and a feeling that the knee may give way can also occur. Explore [Knee Pain](/symptoms/knee-pain/), [Knee Swelling](/symptoms/knee-swelling/) and [Difficulty Climbing Stairs](/symptoms/difficulty-climbing-stairs/) for symptom detail.

The condition reflects gradual changes in the knee’s cartilage, bone, joint lining and supporting tissues. A previous knee injury or operation can alter how force passes through the joint. Repeated loading, muscle weakness and inflammation around the joint may add to symptoms, although discomfort does not always match the appearance of the joint on an image.

Symptoms often fluctuate rather than follow a straight path. Activity, muscle conditioning, sleep and other health issues can influence a flare. Some people remain active with manageable symptoms; others develop more persistent pain, stiffness or loss of function. A new, hot, severely swollen knee or sudden inability to bear weight needs prompt medical assessment.

Risk is influenced by age-related joint changes, earlier ligament or meniscus injury, previous fracture, alignment differences, family tendency and body weight that increases load on the knee. Work or sport involving frequent kneeling, squatting or impact may also contribute. Having a risk factor does not determine whether symptoms will develop.

A clinician asks where pain occurs, when it started, what activities aggravate it and whether the knee locks or gives way. They assess walking, alignment, swelling, tenderness, movement and strength. Weight-bearing X-rays may show narrowing or bone changes; other tests are chosen when injury, infection or another condition needs consideration.

Treatment is matched to pain, function, examination findings and personal goals. Physiotherapy and strengthening can improve support and movement; pacing, walking aids or a brace may help selected people. Medicines or an injection may be considered after checking medical history. Persistent symptoms despite non-surgical care can lead to discussion of [Partial Knee Replacement](/treatments/joint-replacement/partial-knee-replacement/), [Robotic Knee Replacement](/treatments/joint-replacement/robotic-knee-replacement/) or [Total Knee Replacement](/treatments/joint-replacement/total-knee-replacement/).

Break demanding activities into shorter periods and alternate movement with rest. Low-impact exercise, gradual strengthening and supportive footwear can help maintain function. Use handrails on stairs and choose a walking aid only after it has been fitted and explained. Track triggers and goals so follow-up can focus on changes that matter to you.

Pain and stiffness can reduce walking distance, sleep quality, work participation and confidence on stairs. Avoiding movement may then weaken the thigh muscles and make the knee feel less stable. A clinician should review rapidly increasing swelling, marked warmth, fever, a new injury or inability to move or bear weight.

You cannot prevent every case, but you can reduce avoidable strain by recovering fully from injuries, building leg and hip strength, varying repetitive tasks and increasing activity gradually. Maintaining a weight that is healthy for you may reduce load on the knee. Do not ignore persistent pain after an injury.

See an orthopedist or physiotherapist when knee pain, stiffness or swelling limits stairs, walking, sleep or work, or when self-care is not restoring function. Bring a list of medicines, prior injuries and activities you want to resume. A specialist can distinguish osteoarthritis from meniscus, ligament or inflammatory problems and set a staged plan.