I have popped my knee out of socket 3 times. I have been diagnosed with patella instability, bursitis and plica. I recently (2 weeks ago) got tripped during a basketball game landed flat on my bad knee, heard a pop and had it pop out of socket again. There was pain and swelling. The swelling happened within a few minutes of my injury. I still have a lot pf pain and swelling. I'm hoping that I haven't torn something in my knee.