Causes of a swollen knee
Arthritis is a common cause of a swollen knee, as the body produces extra fluid within the joint. How much fluid is produced changes over time and can be related to activity, so using the knee more (such as when walking, gardening or climbing stairs) will often cause more swelling.
Prepatellar bursitis happens when fluid accumulates in the bursa, a thin fluid-filled sack, which sits on top of the patella (knee cap) outside the knee joint.
This can be caused by trauma or overuse, resulting in pain and swelling on the knee cap.
Symptoms of bursitis include:
- Dull, achy pain
- Skin feels tender or warm
- More painful when you move your knee of press on it
- Redness – this may be harder to spot on darker skin
If you still have a swollen knee after resting the joint, it’s a good idea to see a doctor. They will take a sampleof the fluid and test it for infection or other conditions, such as gout. If you have an infection, this can be treated with antibiotics. If your bursitis is not caused by an infection, you may be given a steroid injection in your joint to help reduce the swelling. If your bursitis is severe, or keeps coming back, you may need it surgically drained. This is a simple procedure which can be done in outpatients. In rare cases, you may need your bursa completely removed.
Gout is caused by a build-up of uric acid crystals in the joints. Common symptoms of gout are an inflamed, swollen knee and sudden, severe pain. Pseudogout has a similar presentation but is caused by a build-up of calcium crystals.
People who suffer from gout often have acute episodes, with swelling starting suddenly in one or more joint (usually the big toe). This can be triggered by alcohol and certain foods or medicines, but it can also have no apparent cause.
Gout is diagnosed by removing a small fluid sample for analysis to see if it contains crystals.
Once your consultant has diagnosed gout or pseudogout, they can provide advice and prescribe anti-inflammatories and other medicines for mild attacks, as well as offer injection therapies for moderate or severe cases.
Trauma to the knee can result in a swollen knee, which will come on quickly over 24 hours. Your knee will be investigated, and a sample of the fluid will be taken to see if it contains blood.
The most common causes of blood in the knee are torn ligaments, most frequently the ACL, or a fracture. In these cases, swelling will occur within minutes of the injury.
If there is no blood in the fluid, this can indicate a meniscal tear or a ligament sprain. In these cases, the swelling will start quickly within hours of the injury.
If you’ve injured your knee, it’s a good idea to see a doctor who can check for damage and test if there is blood in the fluid. Surgery is not always required, and your consultant will advise you on the most suitable investigation and treatment plan for the type of injury you’ve sustained and your activity levels.
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If you’re worried about your swollen knee and would like to ask any questions or book an appointment, contact our specialist team.
Our friendly team will do their best to = find you the earliest appointment possible with the best specialist for your needs.