l dislocated my knee a few years ago and since then it keeps dislocating if l turn it suddenly or knock into something. l been to the doctors and they just pass it off with some other reason. It is very annoying cos it can happen anywhere, last time just yesterday it happened at work. Why does it keep doing it and is there anything l can do to stop it happening?

Is ur knee actually dislocating or is it sliding out of the groove?
In a true dislocation, u would not be able to get the knee back in place yourself. This has to be done at the hospital, & is a procedure called a MUA. Manipulation under anesthetic. Dislocation is extremely painful, & would allow no weight on ur leg. The knee also looks deformed.

In sublexing patellas, the knee slides out of the groove. You can push it back in place by yourself, or sometimes just stand on it to slide it back in place.

Dislocating kneecap or sublexing kneecap, is almost always caused by a muscle imbalance. The strong quad muscle usually pulls the kneecap off . You can try going to physiotherapy to try & strenghten the inside muscle (sorry, can not remember the name) Sometimes physio will tape ur kneecap in the proper position.
Surgery is an option if it gets bad enough. My daughter had a surgery called a lateral release. Basically the quad muscle is snipped, to prevent it from pulling the kneecap off.

Iyyaaa
my sis had same problem bout a year ago
they sed she had patella subluxation
dunno if this helps lol but she had the tendons and muscles tightened and was in a full lenght leg cast for 6 weeks
n shes alright now
bi xx