A common complaint involving the knee joints involve painful swelling, and patients have sworn to the debilitating effects of this malady. Doctors could sort out a few causes. The cause of knee pain and swelling must be pinned down if treatment options are to be determined. This would always require a visit to a GP or a specialist. In some cases, the condition results from a chronic disorder that causes gradual swelling and bouts of pain that comes and goes. In other cases, the problem arises quite suddenly causing acute pain and swelling. Either case must be evaluated by a physician.

Synovial joints like the ones you have in your knees contain fluid, which lubricates the cartilage tips of the bones and prevent the damaging effects of friction. The surrounding regions are also bathed in fluid to protect tendons and ligaments. However, there are arising instances when fluid would accumulate and cause swelling of tissue. Too much fluid than is necessary in and around the joints is a physiological anomaly that causes symptoms ranging from simple discomfort to disability.

One cause of  knee pain and swelling is acute trauma, as when one bumps his knee onto a hard surface violently. Injury and damage to the cartilage or ligaments in the knees cause production of fluid. In many cases, disruption of or blockage in blood circulation causes accumulation of blood within the affected tissues. The build-up of blood in the knee joint can be due to a torn ligament, bone fracture, or an injured knee cartilage. When blood enters the joint cavity, the progression of pain and swelling occurs rapidly, often minutes after the trauma is sustained.

There are also injuries that do not result in blood accumulation. A sprained ligament or an injured meniscus produce build up of non-bloody fluid within the knee joint cavity. This kind of swelling happens slower than the one caused by blood accumulation. The swelling may can continue hours and even days after the injury.

Some patients may not have rapid symptoms. Instead, they experience gradual development of the disorder. Chronic swelling and pain are usually symptoms of arthritis. The swelling may come and go, so does the pain. Knee joint arthritis causes production of unnecessary fluid in the affected joint, which grows bigger than the normal knee. Arthritic swelling is aggravated by certain activities.

While many cases may be due to injury or damage to the joints, some instances of excruciating swelling are due to infection. Surgical procedures to the knee can introduce infection through the use of unsterilized instruments. Another cause of knee pain and swelling is gout, which occurs as a result of accumulation of uric acid crystals in the knee joint. Another similar condition called pseudogout is caused by calcium crystals.