I didn't detail it. I've been very public and real about a lot of things here, but I just wanted to keep this one to myself, you can read my post about it here: Wolf's Log: From Cub to Direwolf
It's rare, unknown why it happened to me, and structural in nature - meaning, not just soft tissue related. Not tendonitis or tendonosis. There is also no current slam dunk fix. I'm attempting a first course of treatment this week, and I'm hopeful it will help, but not banking on it. There's a decent chance I'll be stuck with this severe pain with resisted knee extension (or eccentric flexion) for the foreseeable future.