Knee Swelling

What knee swelling usually means

Swelling is the knee's response to something irritating it. Fluid can collect inside the joint, often called water on the knee, or in the soft tissues and bursae around it. Swelling inside the joint makes the whole knee look puffy, especially around the kneecap, and makes it hard to bend fully. Swelling in a bursa forms a more localised lump, such as on the front of the kneecap or behind the knee.

The most useful clue is timing. Rapid swelling within an hour or two of an injury usually means blood in the joint and a significant structural injury. Swelling that appears overnight or the next day, or comes and goes with activity, more often reflects a meniscus tear, cartilage problem or arthritis. Swelling with heat, redness and fever is different again and needs urgent care.

Common causes and how they tend to feel

• ACL tear: a pop with a twisting injury, then the knee balloons within hours, feels tight and later unstable
• Kneecap dislocation: the kneecap shifted out and back, followed by rapid swelling and tenderness on the inner side
• Meniscus tear: swelling the day after a twist, recurring after sport, with pain on the joint line and sometimes catching
• Fracture: swelling after a fall or impact with severe pain and difficulty bearing weight
• Osteoarthritis: a stiff, puffy knee that swells after a long day on your feet or more activity, in adults over about 50
• Bursitis: a soft, localised swelling on the front of the kneecap, often in people who kneel a lot
• Baker's cyst: tightness or a lump behind the knee
• Gout, pseudogout or inflammatory arthritis: a sudden, very painful, warm swelling without injury
• Infection: a hot, red, swollen knee with fever, especially after a cut, an injection or surgery

What you can do now at home

If there are no red flags, rest the knee from sport and long periods of standing, but keep it moving gently so it does not stiffen. Apply ice wrapped in a cloth for 15 to 20 minutes several times a day, raise the leg above the level of the heart when resting, and use a light compression sleeve if it is comfortable. Simple pain relief from a pharmacist may help if it is safe for you.

Try to fully straighten the knee several times a day. Do not return to football, padel or running until the swelling has gone and the knee moves fully, because playing on a swollen knee raises the risk of further damage.

Red flags that need urgent care

• A hot, red, swollen knee with fever or feeling unwell, which can be a joint infection and is an emergency
• Rapid swelling after an injury with severe pain or inability to bear weight
• The kneecap is out of place or the knee looks deformed
• The knee is locked and will not straighten
• Calf swelling and pain, particularly after a long flight, which may be a blood clot

Go to an emergency department the same day for any of these.

How a knee surgeon in Doha works it out

Dr. Gelber asks how and when the swelling appeared, whether it followed an injury and whether it keeps returning. He examines where the fluid is, how much there is, the range of movement, ligament stability, meniscus tests and the kneecap. Temperature and skin changes are checked for signs of infection or inflammation.

X-rays look for fractures, loose bodies and arthritis. MRI is usually advised after an injury with rapid swelling, because it shows ligament, meniscus, cartilage and bone damage clearly. If infection or gout is a possibility, fluid may be drawn from the knee with a needle and tested, which also relieves the pressure.

When to book at Aman Hospital

Book an assessment if your knee swelled after a sports injury, if swelling keeps coming back after activity, if it has not settled within about a week of rest, or if it comes with catching, locking or the knee giving way. A swollen knee after a twist in a young athlete deserves an early examination, because an ACL or meniscus injury is common and some meniscus tears do better when repaired early. Treatment then depends on the cause and ranges from physiotherapy to keyhole surgery.