Bummer!
But...we all did silly things when we were young. I've lost count of the bones I broke over my younger years.
Broken toes, wrist, arm, leg, crushed fingers...
But I learnt eventually.
(Self: "If you do that boy it's gonna hurt. Don't do it!")
Yeah...I did learn...but it took a long time.
And I don't know how many times doctors have stitched me back together...
So your boy will recover.
And most probably go on to break more bones yet. It's all part of 'growing up'.

(I have stainless pins in the fingers that I crushed on my right hand. Very often they set off the metal detectors at airports. I've got to stand outside the machine and poke my hand back in to verify that it's my bare hand doing it.)