What should you know about swollen under knee cap?

A puffy area below the kneecap can come from irritation where a tendon attaches, a fluid-filled bursa, or fluid within the knee that has moved forward. Repeated kneeling can irritate a bursa. Gout can present with sudden, hot, painful swelling around a joint. Knee osteoarthritis may cause activity-related swelling and stiffness, while an ACL tear or meniscus tear can follow a twist with instability, catching, or joint-line pain. A Baker's cyst is usually felt behind the knee but can accompany broader knee swelling. The exact location, timing, and trigger help distinguish these possibilities.

Assessment may include checking alignment, tenderness, strength, stability, and range of motion. Imaging or joint fluid testing is considered when the examination suggests it.

Pause kneeling, running, and jumping until walking is comfortable. Elevate the leg and use a wrapped cool pack briefly after activity or a minor injury. Keep the knee moving gently within comfort so it does not become stiff. Do not puncture or squeeze a lump. Seek an appointment if swelling recurs, persists, or interferes with stairs, sleep, or work.

Obtain urgent care for a hot red knee with fever, severe pain, rapidly increasing swelling, or inability to bend or bear weight. After a twist or fall, urgent assessment is needed for deformity, locking, marked instability, or numbness. Sudden calf swelling with chest pain or breathlessness requires emergency help.

Ask which tissue is swollen, whether an X-ray or other scan is appropriate, and which exercises or supports are safe. Describe kneeling, sports, falls, clicking, locking, fever, and previous gout or knee disease.