I've been living with his exact injury.  I wish him the best.  Hurt mine playing sports in high school... and the meniscus finally gave way while skiing.  Obviously did not play professional sports but was able to be very active for another 10 years consistently playing basketball, flag football, etc..... 10 years after my initial injury the cartilage started to wear off.  Little chunks would would pop off and float around my knee.  Was pretty gnarly, I could see the cartilage poking out of the side of my knee and I could literally grab it with my fingers and move it around under the skin.  Luckily for me, my knee is only bone on bone on the under side so the only real pain is when my knee is bent.  Makes normal day life much better this way.  Running is out of the question but can walk and ride my knee with minimal pain.  Hopefully he'll luck out later in life as well and will be able to live fairly normally.

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