MRI Results of Knee

I have some questions about the results of my MRI of my knee.
The history is, while deployed, i began running for about 30min/day (4-5 days/wk) last December, a few weeks later my knee started to hurt. No signs, just started to hurt, i couldn't run through the pain. I stayed off it for a day and tried it again and my knee felt tight. I went to the clinic on base and they gave me Ibuprofen, ice packs, and a knee brace. I also couldn't really "rest" it while at work so i had to wait til i got home to apply the RICE method. I waited for about 4-6 weeks to try limited weight training to regain strength. I did use the elliptical while i was there. It hurt off & on the rest of the deployment.
I returned to the states in May, got an X-ray (patella mis-aligned) & an MRI (Poptileal Cyst 3.5cm & Bursa 1.1cm behind Knee), i also did about a month of PT & received a Cortizone Shot.
All was going well until i was working out a couple of weeks ago and felt a sharp pain in my knee again. I stayed off it that week, iced it, & wore a brace. I went shopping about 5 days later (minus the brace) and my knee felt like it was going to give out on top of the fact that i could barely walk without it hurting like crazy. The doc referred me to Ortho & gave me vicodin to sleep at night. Ibuprofen just wasn't cutting it!
Now when i walk without a brace, my knee feels weak & there is significant pain around my patella.
I had a second MRI done on my knee a week ago.
Results:
-A small amount of joint fluid is seen around the patellofemoral compartment.
-It also lists that there is a small amount of fluid in the medial collateral ligament bursa. I'm not sure if that is the same as the joint fluid!?!
-A small amount of subcortical marrow edema is seen in the posteromedial aspect of the medical femoral condyle. (aka small bone bruise?!?!)
-The popliteal cyst is no longer visualized.
I am wondering, if no tears showed up, then why does my knee feel unstable & why is the pain around my patella so significant?
Does anyone have any advice?

Your MRI sounds like patello-femoral syndrome. If this is right then your knee feels unstable because of a reflex inhibition of your quad muscles because of the pain you experience.

MRI could also point to begining stages of an arthritic joint......

Definitely follow up with your doc and see what he/she says. If it is patello-femoral syndrome ask for another rehab referral.

He diagnosed it as a patellar subluxation. I forgot to ask him if it subluxated when i injured it and then the pain hit my knee...or...was it subluxated the 2.5 weeks i couldn't walk without being in alot of pain?:confused:
Gotta do a few months of PT and hopefully this will NEVER happen again!