What should you know about DVT and knee swelling?

A deep vein thrombosis is a clot in a deep vein, usually in the leg. The swelling may involve the calf, knee region, or a larger part of one leg rather than being limited to the joint. Skin warmth, tenderness, heaviness, or a change in colour can occur. Knee swelling itself is often related to fluid inside or around the joint; examples include a Baker's cyst, gout, bursitis, osteoarthritis, a meniscus tear, or an ACL tear.

Symptoms alone cannot confirm or exclude a clot. A clinician may examine both legs and decide whether urgent testing is needed, especially after recent immobility, surgery, injury, long travel, pregnancy, or a previous clot.

If one leg has new unexplained swelling with pain, warmth, or tenderness, contact an urgent medical service today for advice. Do not massage the swollen area or start compression without professional guidance. Avoid strenuous exercise until assessed, and tell the clinician about medicines, recent procedures, injuries, and periods of limited movement.

If a joint cause is confirmed, the plan may include rest from aggravating activity, prescribed treatment, physiotherapy, or a procedure such as joint aspiration when appropriate. Keep the focus on the confirmed cause rather than assuming that every swollen knee is a clot.

Call emergency services immediately for sudden breathlessness, chest pain, coughing blood, fainting, or a very fast heartbeat with leg symptoms. These can signal that a clot has travelled to the lungs. Seek urgent assessment for rapidly increasing one-sided swelling, severe pain, a cold or pale foot, or new weakness.

Could this swelling be in the joint, the surrounding tissues, or a vein? Do I need urgent imaging or blood tests? Which activities, medicines, or compression options are appropriate while the cause is being checked? What warning signs should prompt emergency help?