Swelling in a knee joint may limit knee flexibility and function. For example, a person may find it difficult to fully bend or completely straighten a swollen knee, and the joint may naturally bend 15 to 25 degrees while the leg is at rest.1
Depending on the underlying condition, the swollen knee may exhibit no other symptoms or it may be painful, red, and/or difficult to put weight on..
2 Potential Causes of Knee Swellingthe most common causes of knee swelling, are injuries, osteoarthritis, and bursitis, as well as less common causes, are Baker's cysts and reactive arthritis.
Whether water on the knee is mildly annoying or painfully debilitating, a person will want to identify the likely cause and treat the symptoms to help mitigate future problems. Chronic or long-standing swelling may lead to joint tissue damage, cartilage degradation, and bone softening, therefore treatment is usually recommended.