I played football when I was in high school. I THOUGHT I knew all of the dangers. I saw Earl Campbell barely able to walk. I saw a lot of limping by the former players and always assumed it was a rough sport on your legs. I thought, I may have an ankle or knee issue down the road. I never considered what these guys are going through now.

If you haven't heard why Calvin Johnson retired, concussions had a lot to do with it. He said recently, concussions happen "every other play" in the NFL. Click here to read that. He said he suffered hundreds but never was officially diagnosed with one in his career.

Now, to Paul Hornung. He is 80 years old. He played in the 50's and 60's. He is suing helmet maker Riddell claiming they knew about the dangers of concussions 5 decades ago and didn't say a word. Click here to see the full story. 

The argument is, "you knew the dangers of playing football."

Not everyone really did and not everyone was told the truth.

Riddell sure profited off it for years.