I had cartilage removed from my left knee a year ago, but since my rehabilitation my knee now clicks whenever I start to run. The clicking wasnt painful to begin with, just annoying. Now it is both. The clicking is on my lateral side to the side of my kneecap. What is causing it and how can I stop it please?

The knee joint is a very complicated joint. Although in school we are taught it is a hinge joint, it has several parts - all of which can go wrong!!

The femur (the thigh bone) has a joint with the tibia (shin bone) that is so big that it is arranged as 2 joints. There are 2 "washers" inside between the bones called meniscuses (or menisci) - these can get ripped and when they are removed people say they have "had their cartilages removed".

On top of this, there is then the patella (knee cap) which also has a sliding joint over the bottom of the femur.

Clicking sounds like there is something getting caught in one of these joints - and if it is now painful, that is even more likely.

It can be a bit of meniscus that is still in there, or a bit of bone that might have come from early arthritis (wear and tear).

Unfortunately it is unlikely to get better by itself - you will probably need to see an orthopaedic surgeon and have an MRI. You might need an arthroscopy (keyhole operation) but it is safer and less damaging to have an MRI first - if your surgeon thinks it appropriate.

You should check the orthopaedic section of the specialist websites on Medical Pages.