Bad place for a break. Tibia fx frequently go to nonunion because of poor blood supply, especially distally.
He is young so there is less chance of a non union but the position of the break & the force of the trauma increase his chances of nonunion. I wish him good doctors & rapid healing.
I did this on a motocross bike late in my teen years. Both bones, same spot. Took almost 2 years before everything felt totally normal again.
"Fractured tibia, Sargeant....Fractured tibia, Sargeant...OOH, proper little mummie's boy aren't we?"