A swollen knee that develops immediately after an injury, within minutes, is usually due to haemarthrosis, where blood accumulates in the joint. Essentially what happens is that a structure inside the knee gets damaged and starts to bleed, building up pressure in the joint. The swelling is normally profuse and the knee balloons up. It will feel tense and very sore and is often accompanied by bruising, although that may take longer to develop.
Knee swelling is sometimes referred to as “water on the knee.” The medical term for this condition is knee effusion. Water on the knee can result from an injury, chronic overuse, or disease. Swelling in a knee joint may limit knee flexibility and function. 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. At Precision Care Medical & Sports Performance our medical providers will help you diagnose and treat this condition.