What Diseases Are Indicated by Knee Swelling?

According to the scientific service of Saed News, swelling of the knee is a common issue that results from the accumulation of fluid around the knee joint. This problem is also referred to as "water on the knee." This article discusses the causes of this condition, its various types, the best treatment methods, and how to prevent recurrence.

Knee swelling indicates a problem in or around the knee joint. Usually, this issue arises after an injury, but sometimes the cause is deeper and not immediately obvious. If the swelling is minor, it may not be noticeable, but even a small amount can cause problems. In other cases, knee swelling is more visible and can be seen clearly.

Causes of Knee Swelling The knee has a joint capsule that functions like a bag, covering the entire joint. This capsule contains synovial fluid, which nourishes the joint and keeps it lubricated, allowing for smooth movement (similar to oil in a car). The capsule acts as a container, holding synovial fluid within the knee joint.

Knee swelling usually occurs when excess fluid accumulates in the capsule. The causes of this include:

• Bleeding in the Joint: Also known as hemarthrosis, this is often caused by an injury and leads to rapid swelling. This type of swelling can be very painful.

• Accumulation of Synovial Fluid: Synovial fluid accumulation, or "water on the knee," tends to develop gradually and may resolve on its own, depending on the severity of the condition.

Types of Knee Swelling and Their Causes Knee swelling generally falls into one of the following categories:

• Rapid Swelling After Injury: Occurs quickly after an injury.

• Delayed Swelling: Appears hours after an injury.

• Gradual Swelling: Typically fluctuates and occurs without a clear injury.

• Sudden Swelling Without Injury: Occurs suddenly without any injury.

Rapid Swelling After Injury This type of swelling appears within minutes after an injury and is often the result of hemarthrosis, where blood accumulates within the joint. When this occurs, the internal structures of the knee are damaged, leading to bleeding and increased pressure in the joint. This type of swelling is usually severe and makes the knee larger and more painful.

Common causes of rapid swelling after injury include:

• Ligament Tear: A complete tear of the ligament, particularly the anterior cruciate ligament (ACL), is the most common cause of swelling from hemarthrosis.

• Meniscus Tear: A tear on the outer edge of the cartilage on the knee. Symptoms include the knee locking when trying to move and pain while ascending or descending stairs.

• Bone Fracture: A fracture in one of the knee bones, such as the patella, can cause swelling.

Delayed Swelling After Injury If knee swelling develops a few hours to days after an injury, it is likely due to increased synovial fluid, or "water on the knee." This type of swelling is usually not as severe as the rapid swelling from hemarthrosis, and the pain may not be as intense.

Gradual Swelling Without Injury This type of swelling develops slowly and is a sign of a more serious issue in the knee. The fluid in the knee fluctuates and can vary in amount.

• Arthritis: Osteoarthritis is the most common cause of gradual swelling and water retention in the knee. Arthritis damages the cartilage and bones, prompting the body to produce more fluid in the knee. Other symptoms of arthritis include stiffness and creaking of the knee.

• Overuse of the Legs: Overuse or injury to the legs can irritate the joint, prompting it to produce more fluid to protect itself.

Sudden Swelling Without Injury Sometimes knee swelling appears suddenly without any obvious injury. Major causes of this type of swelling include:

• Infection: Infections in the knee joint can lead to an increase in synovial fluid, causing swelling. This swelling usually occurs after surgery or deep cuts but can sometimes spread from other parts of the body.

• Gout: High uric acid levels in the body can form sharp crystals in the joints, leading to inflammation and water retention in the knee. Treatment typically involves medication and dietary changes, with a plant-based diet being highly effective.

Other Causes of Knee Swelling Typically, knee swelling remains inside the joint capsule as the capsule acts as a barrier preventing fluid from escaping. However, swelling may also occur outside the capsule due to the following:

• Bursitis: Small sacs filled with fluid, called bursae, sit between the bones and soft tissues of the body to reduce friction. If there is excessive friction, they become inflamed.

• Patellar Bursitis: This occurs due to bursitis in the front of the knee, leading to swelling.

• Hematoma: Trauma to the soft tissue around the knee can cause bleeding, which may collect and form a hard lump.

Rare Causes of Knee Swelling Rare causes of knee swelling include:

• Patellar Displacement: The patella may move out of its groove due to severe injuries, leading to swelling.

• Patellar Tendonitis: Inflammation of the patellar tendon can cause small swelling in the front of the knee.

• Tumors: Various tumors can cause knee swelling and may lead to fatigue, weight loss, and a general feeling of illness.

• Deep Vein Thrombosis (DVT): A blood clot in one of the deep veins, usually in the thigh, can cause swelling, pain, and redness, often after prolonged rest, surgery, or air travel.

Treatment of Knee Swelling Treatment for knee swelling depends on the underlying cause, but common treatments include:

• Ice: Applying ice can reduce bleeding and swelling.

• Compression: Using a knee brace can help reduce swelling by compressing the knee.

• Medication: Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can help reduce swelling and pain.

• Injections: Corticosteroid injections can help reduce inflammation and pain.

• Elevation: Keeping the leg elevated above the level of the heart can help reduce swelling through gravity.

• Rest: Reducing activity can relieve pressure on the knee and help reduce swelling.