Slightly Dislocated My Left Knee AGAIN

I’m for some reason (read sprained left MCL years ago and have since dislocated the knee cap multiple times) prone to knee cap dislocations. Knee cap slides to the outside and the knee feels like it collapses. I can usually catch it when it happens so the dislocations are not that severe but I don’t have the foggiest why it keeps happening. I’ve gotten film taken and all other ligaments are intact. Any ideas?