Overview
Knee osteoarthritis is a common, long-term wear-and-tear condition that affects the cartilage and the underlying bone in the knee joint. Over time, the smooth cartilage surface breaks down and the joint can become inflamed, stiffer, and less able to absorb shock. This breakdown can also change how the knee tracks and moves, which contributes to pain during walking, stair climbing, or standing. Symptoms often build gradually and may worsen with activity as the joint becomes more irritated.
Symptoms
Pain is usually felt in the inside or sometimes outside part of the knee and may worsen with activity and improve with rest. Many people notice morning stiffness that typically lasts less than about 30 minutes, along with stiffness after sitting. Swelling may come and go, and you may feel grinding or crackling with movement. As arthritis progresses, walking distance, stair use, and getting up from a chair can become more difficult.
Causes
Knee osteoarthritis develops when the knee joint tissues are gradually overloaded or damaged, leading to cartilage breakdown and changes in the bone beneath it. It often follows a history of joint injury, abnormal alignment, or repetitive strain that increases stress on specific parts of the joint. Inflammation within the joint can further amplify pain and stiffness even when the cartilage damage is the underlying driver.
Risk Factors
Risk increases with age because joint cartilage naturally loses resilience over time. Prior knee injury, such as meniscus or ligament damage, and repeated high-impact activity can accelerate wear. Extra body weight increases the load transmitted through the knee and raises risk, while muscle weakness and poor movement mechanics can make the joint work harder. Genetics, abnormal knee alignment, and occupational or sports demands that stress the knee repeatedly also play a role.
Prevention
You can reduce the risk of developing or worsening knee osteoarthritis by maintaining a healthy weight and using activity that strengthens muscles without overloading the joint. Building and maintaining quadriceps and hip strength, improving flexibility, and using good mechanics during walking, stairs, and sports can lower joint stress. Choosing lower-impact exercise such as cycling, swimming, or walking on flat surfaces, and avoiding sudden increases in activity, can help protect the knee.
How the Diagnosis Is Evaluated
Clinicians usually start with a detailed history of pain timing, stiffness, prior injuries, and what activities trigger symptoms. A physical exam focuses on tenderness, range of motion, swelling pattern, alignment, and stability, and may assess muscle strength and gait. X-rays are commonly used to look for joint-space narrowing, bone spurs, and other typical changes, but not every patient needs advanced imaging. Blood tests or additional evaluation may be used when symptoms suggest infection, inflammatory arthritis, or other causes of knee pain.
Nonsurgical Treatment Options
Non-surgical care aims to reduce pain, improve function, and slow symptom progression. Many people benefit from exercise therapy led by a physical therapist, including strengthening (especially quadriceps and hip muscles), range-of-motion work, and low-impact aerobic activity. Weight management, topical or oral anti-inflammatory medications when appropriate, and supportive devices such as bracing or a cane can reduce stress on the painful part of the knee. In some cases, corticosteroid injections can provide short-term relief during flare-ups, while hyaluronic acid injections such as Orthovisc may help some patients with persistent symptoms. Platelet-rich plasma (PRP) injections may be considered for selected patients, and stem cell or adipose allograft approaches are typically viewed as investigational with variable evidence and results.
When to Seek Medical Attention
Seek prompt medical attention if you have a hot, very swollen knee, fever, or severe pain that came on suddenly, as these can suggest infection or another urgent problem. Get evaluated urgently if you cannot bear weight, the knee locks in place, or you notice rapidly worsening swelling or deformity. You should also be seen soon if symptoms are progressing despite home care, or if you develop new numbness, significant weakness, or symptoms in other areas of the body.
Frequently Asked Questions
It often feels like an ache or soreness that worsens with walking, stairs, or standing and improves with rest.
No, while age increases risk, prior injuries, alignment issues, weight, and genetics can also contribute.
For many people, strengthening and low-impact conditioning through a structured exercise program plus activity modification provides the best long-term benefit.
Yes, corticosteroid injections can help some people temporarily, and hyaluronic acid or PRP may be options for persistent symptoms in selected cases.
Next Steps
If your knee pain is persistent or limiting daily activities, start with an evaluation to confirm the cause and determine the best conservative plan. In the meantime, consider gentle range-of-motion work, low-impact activity, and protective strategies like supportive footwear and pacing your activity, and then follow up with a clinician or physical therapist for individualized guidance.