Knee osteoarthritis

Osteoarthritis is a progressive change in a joint over time. In the knee it involves the smooth cartilage that caps the ends of the bones, along with the bone underneath, the lining of the joint, the menisci, and the surrounding ligaments and muscles. As the joint surface gradually thins and the knee adapts, it can become painful, stiff, and less able to do what you ask of it.

Osteoarthritis is common and tends to develop slowly. Having it does not mean your knee is beyond help — many people manage it well for years, and the goal of care is to keep you comfortable and active.

Knee osteoarthritis often causes pain that is worse with activity or after a long day and better with rest, along with stiffness — especially first thing in the morning or after sitting for a while. Some people notice swelling, a grinding or catching sensation, a feeling that the knee may give way, or trouble with stairs, squatting, or long walks.

• Activity-related pain, and sometimes aching at rest or at night
• Stiffness, particularly after inactivity
• Swelling that can come and go
• Loss of full motion — trouble fully straightening or bending the knee
• Mechanical symptoms such as grinding, catching, or a sense of giving way
• Reduced function — difficulty with stairs, kneeling, or longer activity

The amount of arthritis visible on an X-ray and how much a knee bothers a person do not always line up. Some knees look quite arthritic on imaging but cause relatively little trouble, while others cause significant symptoms with more modest-looking changes. Because of this, decisions are based on how you are actually doing — your pain, your function, and your goals — interpreted together with the examination and imaging, not on the X-ray alone.

Evaluation usually begins with your history — what the knee does, what makes it better or worse, and how it affects your daily life and activities — and a physical examination of motion, alignment, stability, and where it is tender. Weight-bearing X-rays are the standard imaging when arthritis is suspected, because they show the joint under load and help gauge the pattern and location of the wear.

An MRI is not routinely required for typical knee osteoarthritis. It may be used when the diagnosis is unclear or when a specific associated problem — such as a possible meniscus tear, a focal cartilage lesion, or another injury — needs to be characterized because it would change the plan.

The right approach depends on you, not on a formula. Several things are weighed together, and the plan often changes over time as symptoms and goals change.

• Your symptoms and how much they limit you
• Your activity goals and what you want to get back to
• The examination, including motion, stability, and alignment of the leg
• The extent and location of the arthritis (which part of the knee is involved)
• What treatments you have already tried and how they worked
• Your overall health and other medical considerations

The core of managing knee osteoarthritis is staying active and keeping the knee and the muscles around it strong. Staying active is generally good for an arthritic knee — thoughtful, appropriate exercise helps rather than harms it. The aim is to modify activity sensibly, not to stop moving.

• Activity modification — adjusting how you do things rather than becoming inactive; often trading high-impact bouts for knee-friendlier options
• Low-impact aerobic exercise such as walking, cycling, swimming, or an elliptical to keep the whole body conditioned
• Strengthening and mobility work for the muscles that support the knee, plus keeping motion
• Physical therapy to guide a program and progress it safely
• Where excess weight is a factor, gradual weight management can meaningfully reduce load on the knee — as one helpful lever among several, not a judgment
• A brace in selected situations, when it fits the pattern of arthritis and your needs
• Injections as one symptom-management option (below)
• Medications used only in broad terms and in consultation with the clinician who manages your care — this page does not give doses
• Keeping up your activity and function, which supports both the knee and overall health

Several injections are used to help symptoms. They are options to discuss individually — their role, evidence, and insurance coverage differ, and none of them reverse arthritis that is already present.

No injection regrows established cartilage or is guaranteed to prevent future surgery. Injections are chosen with you, based on your situation, and this page does not provide dosing.

• Corticosteroid (“cortisone”) injections may provide temporary relief of pain and swelling for some people; the benefit is not permanent and responses vary.
• Hyaluronic-acid injections (viscosupplementation) are used by some clinicians, but the evidence for benefit and the insurance coverage both vary, and professional guidelines differ on their role.
• Platelet-rich plasma (PRP) may be discussed as an option for selected patients; the evidence is mixed, individual responses vary, it is often an out-of-pocket cost, and coverage varies.

It helps to separate two different situations. A focal cartilage injury is a localized “pothole” on an otherwise reasonably healthy joint surface. Osteoarthritis is more widespread wear across the joint. The distinction matters because some cartilage-focused options are aimed at selected focal defects and are not treatments for diffuse arthritis. If you want to understand focal cartilage problems specifically, the articular cartilage page covers them.

Depending on age, the alignment of the leg, which part of the knee is affected, the symptoms, and personal goals, some people are candidates for joint-preservation strategies. These are individualized and are not appropriate for every arthritic knee.

• An alignment-correcting osteotomy, in appropriately selected patients, shifts load away from the more worn part of the knee.
• When a focal cartilage or meniscus problem is clinically relevant alongside early arthritis, addressing it may be part of the conversation.
• The distinction between a focal cartilage injury and diffuse osteoarthritis guides which of these even applies.

Knee arthroplasty (knee replacement) is the primary surgical treatment for advanced, symptomatic knee osteoarthritis when reasonable nonsurgical measures no longer provide acceptable relief or function. It is considered because of how the knee is affecting your life — not simply because arthritis shows up on an X-ray.

At a high level, some knees with arthritis limited to one part of the joint may be candidates for a partial (unicompartmental) replacement, while more widespread arthritis is usually treated with a total knee replacement. Which one — if any — fits depends on the pattern of arthritis and on factors specific to you. The decision is made together, based on your symptoms, function, goals, examination, imaging, and how you have responded to nonsurgical care.

Reach out to a medical professional if your symptoms are worsening in a way that concerns you, or promptly if you have a knee that becomes acutely hot and markedly swollen, a knee that follows a significant injury, or knee symptoms along with fever or feeling generally unwell — which can point to a problem that needs to be looked at sooner rather than later. This website is not monitored for emergencies; for a medical emergency, call 911.