What causes fluid accumulation in the knee?

The knee may refer to the knee joint. Knee joint effusion could be caused by environmental irritation, trauma, synovitis, knee arthritis, gout, and other factors. It is recommended to seek medical attention promptly, identify the underlying cause, and receive symptomatic treatment under the guidance of a qualified physician. The specific analysis is as follows:

1. Environmental irritation: When the knee joint remains in cold and damp environments for prolonged periods, the synovium may secrete excessive synovial fluid, leading to joint effusion. Special treatment is generally not required; however, patients should rest adequately, avoid prolonged exposure to such conditions, and take proper warming measures—such as wearing knee guards—which can help alleviate this condition.

2. Trauma: When the knee joint suffers external impact or sprain, structures such as the meniscus and ligaments may become damaged, potentially causing local inflammation and fluid accumulation. This may also be accompanied by symptoms like knee pain and swelling. It is recommended that after 24 hours of injury, patients apply an ice pack wrapped in a towel to the affected area to promote vasoconstriction, helping control bleeding and relieve pain. After 24 hours, applying a warm towel to the area may improve local blood circulation and reduce swelling.

3. Synovitis: This may be associated with factors such as trauma or chronic overuse. These factors may stimulate the synovium, triggering an inflammatory response and resulting in excessive fluid secretion. Main symptoms include knee swelling and pain. Patients are advised to follow medical instructions when using medications such as methylprednisolone tablets, ibuprofen capsules, or celecoxib capsules for treatment.

4. Knee arthritis: This may be related to excessive use of the knee joint or joint injuries. The condition may irritate the knee synovium, leading to inflammatory responses and fluid buildup, often accompanied by knee pain and swelling. Patients are advised to follow their doctor's instructions when using medications such as celecoxib capsules, glucosamine sulfate tablets, or diclofenac sodium gel.

5. Gout: This is primarily caused by abnormal uric acid metabolism, resulting in deposition of urate crystals in the joints, which triggers joint inflammation and effusion. Symptoms may also include knee pain and fever. Patients are advised to use medications such as benzbromarone tablets, colchicine tablets, or allopurinol tablets under medical supervision to manage the condition.

In daily life, patients are encouraged to drink plenty of warm water, maintain good local hygiene, wear loose and breathable clothing, all of which may support recovery.