A sprained knee swells. This common reaction follows an injury to the ligaments around the knee joint. A sprain occurs when these tough, fibrous bands of tissue, which connect bones and stabilize the joint, are stretched or torn. Swelling is a natural and immediate part of the body’s protective and healing processes.
The Body’s Response to a Sprain
When a ligament in the knee is sprained, the body initiates an inflammatory response. This process involves the dilation of local blood vessels, increasing blood flow to the injured area. This heightened circulation delivers immune cells and biochemical mediators necessary for tissue repair.
The increased blood flow leads to a leakage of fluid from the capillaries into the surrounding tissues. This accumulation, known as edema, causes the visible swelling around the knee joint. Swelling immobilizes the injured area, protecting it from further damage, and brings essential components for healing directly to the site of injury. While swelling indicates an injury, its presence alone does not determine the overall severity of the sprain.
Identifying Swelling and Other Indicators
Identifying swelling in a sprained knee involves comparing the injured knee to the uninjured one. The sprained knee may appear larger, and the normal contours of the joint might be obscured. The skin over the swollen area can also feel warm to the touch due to increased blood flow.
Beyond swelling, a sprained knee presents with other indicators. Pain is a prominent symptom, varying in intensity and often localized to the specific ligament affected, worsening with movement or weight-bearing. Bruising can develop, leading to discoloration around the knee. Tenderness to touch, a limited range of motion, and a sensation of instability or the knee “giving way” are common. These combined symptoms, along with swelling, offer clues about the potential extent of the knee injury.
Initial Care for a Sprained Knee
Immediate care for a sprained knee focuses on managing swelling and pain. The RICE protocol is a recognized first-aid approach for soft tissue injuries like sprains. Resting the knee by avoiding activities that cause pain helps protect the injured ligaments from additional stress.
Applying ice to the affected area for 15-20 minutes at a time, several times a day, helps constrict blood vessels, reducing blood flow and minimizing swelling and pain. Compression, achieved by wrapping the knee with an elastic bandage, provides support and limits fluid accumulation. Elevating the injured knee above the level of the heart assists in reducing swelling by promoting fluid drainage away from the joint. Over-the-counter pain relievers, such as NSAIDs like ibuprofen, can also manage discomfort and reduce inflammation.
When to Consult a Professional
While initial self-care is beneficial for mild sprains, certain signs indicate the need for professional medical evaluation. If you cannot bear weight on the injured leg, or if pain is severe and does not improve with rest, ice, and over-the-counter pain relievers, seek medical attention. Rapidly worsening or significant swelling, or any visible deformity of the knee, are serious indicators.
A popping sound at the time of injury suggests a more severe ligament tear. A sensation of the knee “locking” or repeatedly “giving out” points to potential structural damage. Numbness or tingling below the knee could indicate nerve involvement and requires immediate assessment. If symptoms do not improve after a few days of self-care, a healthcare professional can accurately diagnose the sprain’s severity, ranging from Grade I (mild stretch) to Grade III (complete tear), and rule out other potential injuries like fractures or meniscal tears.