Question
Am 33 year old male.  Years ago, developed kneecap pain and tendinitis from driving I did for a living at the time.  Had a cortizone injection back then.  Also, changed jobs.  Knee pain went away.  However, it really never has felt the same and has felt unstable and out of place almost and does give way once in awhile and fortunately I have caught myself when that has happened.  

I realize I need to do something about that and prevent a serious injury from knee give out.

I have read in many places about eccentric knee exercise and how they have cured kneecap issues.  However, I wonder if my case is different since mine is an injury from repetitive stress injury and not like a sports injury.

Should I try the eccentric exercises?  Also, if I do them, should I use the slant board that I see other people use, or do them flat on the floor?

Or should I get another cortizone shot and a combination of eccentric exercises?

Answer
Check this out, it can help. Get an orthopedic evaluation if things persist.

http://www.google.com/url?sa=t&rct=j&q=patellofemoral%20syndrome%20exercises&sou