Knee popped going down stairs...what did I do?

Might have torn a ligament. Elevate, ice, and see the doctor ASAP.

Do I really have to go to a doctor? What will a doctor do?

@skfinkel She’ll do an exam, try to determine if there’s any ligamentous laxity, and maybe put it in a brace. She may send you to an orthopedic specialist or a physical therapist.

Certainly if it hurts to walk on it by Monday it should be looked it.

Try the classic RICE; Rarebear got part of it. Rest, Ice, Compress, Elevate.

For compression, get an elastic support from pharmacy; give it a few days and then see Doc. (Sorry. No fun.)

If it isn’t swollen it may be the case that you have just trapped a nerve.

The kneecap is held in place by two ligaments, think of it like a train on a train track. If the kneecap is slightly misaligned this can cause a crunching or popping sound when the knee is bent and extended as air rushes in between the cartilage and bone. This can be due to weak core strength if you do a lot of sport but it doesn’t sound like this is the case, in your instance.Whilst walking down the stairs a nerve may have moved away from its normal position and become trapped, in said position, putting abnormal pressure on it and thus pain.

Try having a warm bath to relax the muscles in your leg and massage the area creating movement, if it isn’t too painful, that hopefully will put everything back in its place. If that fails and it doesn’t see signs of improvement by monday go and see your doctor or physiotherapist.

Thanks all. It is swollen, I have taken ibuprofen, am icing it and resting. I will just have to enjoy the beautiful day from inside!

Did it happen while twisting? Look up torn medial meniscus .
I tore mine while running down stairs. I lasted about four days before going to the doc. Surgery was done the next week. I was up on crutches the first two days then took it easy for about a week. No problems since.
Good luck to you.

Why should you see a doc?

Because they can figure out exactly what’s going on.

When something similar happened to me they took X-Rays and discovered I was down to bone-on-bone from lack of cartilage. No wonder it hurt.

But you really should find out PRECISELY what is happening in your particular situation.

Really impossible to tell over the Internet.

I thought a simple cortisone shot would fix me up good as new. Obviously not, but then I don’t have X-Ray eyes like Superman. Neither do you. Go get it properly diagnosed. You’ll be glad you did.

As someone with only half an ACL in my left knee, I agree that you should see a doc about this.