After my Rocket City Marathon fail, I planned on running the Mississippi Blues Marathon. I was really fit and wanted to take advantage of my fitness. Unfortunately, I got a bum knee and had to miss a few weeks of training, which further rained on my winter marathoning parade.
I'm a really analytical person and like trying to find the cause behind things. I wasn't sure what caused my knee problems. Overpronation? Weak quads? Tight rectus femoris? However, I found the most help from a poster on letsrun.com that gave me a ton of detailed, in-depth information about my injury. She felt it could potentially be a secondary issue as a result of something else. Having a kink somewhere in your kinetic chain can have a rippling effect and cause pain in a totally different area.
While you can't diagnose someone or something over a computer (unless you're on Skype with your favorite medical professional), she thought an anterior tilt of my pelvis could have been playing a role. That rung a bell because I've always felt like I lean too far forward when I run. As a result, my hip flexors and glutes don't do their fair share of the work, which wreaks havoc on my illiotibial band and hamstrings, both of which were chronically tight.
After starting some core type work, some psoas and hip flexor stretches and focusing on running more "tall", with a more aligned pelvis, my injury slowly disappeared. My hamstring and illitiobial tightness also went away and now when I run, my glutes actually get tired. Those first few weeks of regular training, they were constantly tired and run-down because they were finally being activated. Whether it was a neuromuscular or muscle strength issue, I don't know...But at least it went away.
To make a long story short, here is a great post about runner's knee, which debunks a lot of myths about the issue and looks at the real causes: