Almost everyone feels knee pain at some point. Most of the time the cause is a tiring day or a sudden movement, and the pain eases in a few days with rest and ice. Some signs, though, tell you the knee needs to be examined.

The 7 signs

Swelling that came on fast. A knee that swells within hours of an injury often has blood inside the joint.
The knee locks. It gets stuck in one position and will not straighten. A common cause is a meniscus tear.
The knee gives way. If it buckles on twists or stairs, the ACL may be injured.
You cannot put weight on the leg. Especially after a fall, this needs an examination the same day.
Pain wakes you at night. Night pain is not simple tiredness.
Redness, warmth and fever. A hot, red knee with a fever is urgent.
The pain lasts more than two to three weeks. Even if it is mild, it is worth finding out what causes it.

What you can do yourself in the first days

Rest the knee, without staying completely still.
Use ice for 15 to 20 minutes, a few times a day.
Keep the leg raised when you sit.
Avoid deep squats and twisting.

What happens at the examination

It starts with a conversation: how the pain began, where exactly it hurts, what makes it worse. A clinical examination of the knee comes next. If needed, a standing X-ray or an MRI scan is requested.

In most cases the treatment is not surgery. It is physiotherapy, strengthening and a change in activity. If the pain comes from wear, see the page on knee osteoarthritis too.

When to call

If you recognise any of the signs above, book an appointment. Bring any tests you already have.