The knee joint is probably the most frequently damaged joint and is particularly vulnerable as it takes the full weight of your body.
However, knee pain isn’t always a joint problem. Learn about the most common causes of knee pain and what you should do.
Inflammation of the joint lining
If you’ve injured the joint recently and it suddenly becomes painful again, the thin layer of tissue lining the joints and tendons may be inflamed – a condition called traumatic synovitis. It usually doesn’t cause any redness or heat.
You should be able to manage injury-related swelling at home with anti-inflammatories, an icepack and rest.
Gout or pseudogout
If the skin over the joint is hot and red, and the pain comes in repeated attacks, the cause is likely to be either gout or pseudogout.
Both conditions are types of arthritis.
Gout usually affects the joint of the big toe first, before affecting other joints. It’s important to correctly diagnose gout, as treatment will prevent future attacks of joint pain and disability.
Pseudogout is a similar condition to gout, but usually affects the knee joint first.
See your GP if you think you have either condition.
Damage to the cartilage at the back of the kneecap
Knee pain that feels worse when going up or down stairs could be a sign of a damaged kneecap – a condition called chondromalacia patellae. This shouldn’t cause any redness or heat around the knee.
The cause isn’t really understood, but it can be linked to overuse of the knee.
You can treat this problem yourself with anti-inflammatories, an icepack and rest.
Bleeding into the joint space
If you’ve recently had an injury to the knee joint, such as a torn ligament or knee fracture, it may cause bleeding into the joint spaces. This is known as haemarthrosis.
This is more likely to happen to people on anticoagulants, such as warfarin.
Signs of haemarthrosis are:
- swelling of the knee
- stiffness and bruising, which occur soon after the injury
You should go to hospital immediately for treatment if you have a very swollen knee.
Less common causes
Sudden pain in a joint is less commonly caused by:
Rarely, the cause may be:
- septic arthritis – a serious condition that causes a painful, hot, swollen joint that you won’t be able to move (sometimes with fever) – see your GP urgently or go to A&E
- haemophilia – an inherited condition that affects the blood’s ability to clot
- a tropical infection
- crumbling of the bone (avascular necrosis) – caused by a lack of blood supply
- repeated dislocation of the joint