On This Is Us, the first of three episodes focusing on "The Big Three" explained how Kevin Pearson broke his knee, which some have believed was linked to Jack Pearson's death. Unfortunately, we still have to wait for that revelation.
In the meantime, after weeks of spiraling out of control, Kevin had a total breakdown, when he returned to his old high school, as he realized all of the dreams and opportunities he's ruined in his life. Justin Hartley's stellar monologue on the school's football field was interlaced with flashbacks of him playing in a game on the very same field, and taking a career-breaking hit to his knee. "Will he get up? Ladies and gentlemen, he will. He'll get up. Kevin Pearson will walk again, just in time to bury his beloved father," said an inebriated Kevin as he provided commentary for his own memory. But that wasn't even his worst.
After sneaking out of a girl's house, Kevin realized he left his dad's pendant there and that's when he officially hit rock bottom. "That necklace, it's the only thing I have left in my life from my dad," said Kevin through tears to Charlotte, the girl he had just slept with. He continued, "It's the only thing I have and I know it's up there. It's a wheel pendant on a little chain. It's on your bedroom floor. It's from where you tore my shirt off." After being completely denied by Charlotte, Kevin crumbled to the ground finally succumbing to the realization that he needed help, as he cried, "I'm in pain out here! Look, I'm in pain here, okay? Can't you see I'm in pain? I just need it to stop. I just need somebody to help me."
The next day, Kevin went over to Randall's house to admit his addiction, and after This Is Us tore at our hearts for an hour, they decided to go ahead and rip it out completely, when Randall told Kevin, "It's okay. I already know. Kate lost the baby."