Knee soft tissue swelling: what to know

Soft tissue swelling may sit over the kneecap, along the sides of the joint, or behind the knee. Repeated kneeling can irritate a bursa; a twist can affect a ligament or meniscus; and a sudden flare of gout can make the area painful, warm, and tender. Knee osteoarthritis may cause activity-related swelling and stiffness. A Baker's cyst can create fullness behind the knee. These conditions can present with swelling, but swelling itself does not identify one cause.

A clinician will ask about the trigger, timing, pain, locking, giving way, fever, and ability to bear weight. They may compare both knees and assess the skin, joint movement, and nearby calf. Further tests are chosen when the examination suggests a deeper injury, infection, crystal inflammation, or another source.

Pause the movement that triggered the swelling and use gentle range-of-motion exercises if they do not increase pain. Elevate the leg when resting, and use a wrapped cold pack for short periods if suitable for you. Avoid pressing, puncturing, or repeatedly massaging a visibly swollen area. Keep a note of activity, swelling location, warmth, and how quickly it changes. If symptoms continue or interfere with walking, arrange an assessment; joint aspiration may be considered for selected problems involving excess fluid.

Get prompt medical advice for swelling that follows a significant twist, keeps returning, or is paired with locking, instability, or reduced movement. Seek urgent care if the knee becomes rapidly swollen and hot, you have fever, the skin is spreading red, you cannot bear weight, or calf swelling occurs with chest pain or breathlessness.

Where is the swelling located, and which structure might be involved? Do I need imaging or fluid testing? Which activities should I modify, and what movement can I safely continue? What change would require urgent review?