What should you know about knee swelling after an injury?

Knee swelling after an injury can involve the joint or nearby tissues and may need examination if function is affected. Record how the injury happened, when swelling began, and whether pain, weakness, or restricted movement followed.

A blow may cause bruising and local inflammation. A twist, sudden stop, or awkward landing can strain a ligament or irritate the meniscus. An ACL tear may be associated with instability, while a meniscus tear may cause catching or difficulty fully straightening the knee. Pain over the front of the knee can involve a bursa. Knee osteoarthritis, gout, or a Baker's cyst may also cause swelling and can coexist with an injury; swelling itself does not tell you which condition is present.

Assessment may include checking the joint line, kneecap, ligaments, strength, and walking pattern. Imaging is considered according to the mechanism and examination findings.

Stop the provoking activity and keep the knee in a comfortable position. Elevate the leg and apply a cloth-wrapped cold pack for short periods. Avoid deep squats, jumping, and twisting until symptoms improve. Gentle movement within a comfortable range can prevent stiffness, but stop if swelling or pain increases. Do not return to sport while the knee buckles or cannot move normally.

Get urgent care for a deformed knee, inability to bear weight, rapidly increasing swelling, loss of sensation, or a foot that becomes cold or changes color. Fever with a hot swollen knee also needs prompt review. Book an assessment for ongoing swelling, recurrent giving way, locking, or pain that interferes with sleep or ordinary walking.

Ask what structure may have been injured, which activities are safe now, and whether a brace or physiotherapy is appropriate. Ask how progress will be measured and whether joint aspiration or imaging would change treatment.