Knee swelling can be caused by a variety of disorders. Fluid gathers in the knee's joint and can cause it to swell and disfigure the area surrounding the knee, including the top of the knee. A large lump--about the size of a grapefruit--can form on top of the knee, making it difficult to both walk and bend the knee. Without proper attention, the condition can become worse over time, and can lead to other problems as well.
Osteoarthritis
Osteoarthritis is one form of arthritis that attacks the joints. Individuals with this disorder may find that an increase in walking or physical activity may cause the knees to swell and become enlarged. According to the Sports Medicine Institute, osteoarthritis only affects the joints, making knee swelling almost impossible to avoid. Individuals with this disorder can also have swollen knees from a lack of movement for an extended period of time. Some of the most common side affects of osteoarthritis include swelling of the joint, tenderness and pain in the knees, and a loss of cartilage.
Obesity
Obesity can also cause knee swelling. The knee's purpose is to carry body weight and evenly distribute the weight to the foot. However, when excess weight is placed on the knee, it can cause inflammation in the knee joint that appears as a large, painful swelling. The pressure from excess weight placed on the knee--as well as the swelling--can cause immobility. Unless the excess weight is reduced, knee swelling will persist and make it much harder to move around. According to BMC Public Health, an online publication from the U.S. National Library of Medicine, obesity is one of the primary causes of knee swelling and inflammation of the knee joint.
Gout
According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, gout can cause severe inflammation of the knee. Gout is a disorder that results when one the body's waste byproducts--uric acid--turns into little crystals that form around the joints. The little crystals cause the joint to become agitated and inflamed, which makes the knee area swell. The disorder is very painful and makes moving around extremely difficult. Individuals who suffer from obesity or osteoarthritis are more susceptible to getting gout as well. The three conditions can cause repetitive knee swelling.
