Different things can cause the knee to swell. It can happen when joint fluid (synovial fluid) builds up in your knee joint. It could be the result of an injury or a health condition like arthritis. MediFind  has compiled a list of conditions that are common causes of knee swelling. Always seek medical attention for an accurate diagnosis. Learn more about how MediFind works here. You can also enter your symptoms into MediFind’s Symptom Checker to receive customized results.  

Osteoarthritis

Osteoarthritis (OA) is the most common joint disorder. It is caused by aging and joint wear. It occurs when the cartilage, which cushions bones in the joints, breaks down. This can lead to swelling, pain, and stiffness. OA typically gets worse over time. Treatment options range from over-the-counter pain relievers to lifestyle changes and surgery. OA is treated by primary care doctors. Locate a primary care doctor near you here.

Bursitis

Bursitis is when a bursa gets inflamed and swells up. A bursa is a sac filled with fluid that acts like a cushion between muscles, tendons, and bones. Bursitis can happen from overuse. It can be caused by a change in activity level like intense marathon training or by being overweight. It affects areas like the shoulder, knee, elbow, and hip. Your doctor might suggest treatments such as ibuprofen or naproxen, physical therapy, or using knee braces or splints to ease swelling. Bursitis is usually treated by orthopedic doctors. Find one near you here.

Baker Cysts

A baker cyst (or popliteal cyst) is a small swelling behind your knee. It is caused by extra joint fluid called synovial fluid. This fluid helps your knee move easier, but sometimes the fluid builds up, creating a little bump. The cyst may feel like a water-filled balloon. Sometimes the cyst breaks open, causing pain, swelling, and bruising on the back of the knee and calf. Usually, no treatment is needed. Your doctor may give you a steroid injection to reduce swelling. The cyst may be surgically removed in rare cases. Get specialized care with an orthopedic doctor here.

Knee Fracture, Sprain, or Dislocation 

When your knee gets injured, like with a fracture, the healing process involves the body creating new bone tissue. This might lead to a lump or callus forming. For knee sprains, swelling can happen around the knee joint, showing up as a lump or bulge. The treatment depends on how bad it is. Orthopedic doctors can help with knee injuries. They’ll guide you on the best steps for healing, such as rest, physical therapy, or other options tailored to your situation. You can find one nearby here.

Rheumatoid Arthritis 

Rheumatoid arthritis (RA) is a chronic, or long-lasting, condition. It happens when the body’s defense system attacks the lining of the joints, particularly in the hands, wrists, and knees. Symptoms include fever, fatigue, loss of appetite, warm and tender joints, and lumps under the skin, called rheumatoid nodules. There is no cure for RA. But medications like disease-modifying antirheumatic drugs (DMARDs) can help manage the disease, slow its progression, and prevent joint damage. Consult a rheumatologist near you here.

Other causes of knee swelling can include:  

• Osteochondroma  
• Inflammation (Gout) 
• Neutrophilic dermatoses  
• Cellulitis 
• Ganglion cysts 

Use our Symptom Checker to add your information and get your custom results.

As children and adolescents grow, they might have knee swelling due to growth or inflammation. Adults are more likely to have swelling because joints undergo wear and tear as people age. 

Knee swelling can happen to both men and women due to injuries or other reasons. Differences in body features may influence how lumps are noticed. 

MediFind provides content for informational purposes only. MediFind does not provide medical advice. This content should not replace a health care professional’s medical advice, diagnosis, or treatment. Contact a licensed health care provider with any questions about your own health. Contact 911 in the event of a medical emergency.