Sounds like he might have either had something fall on his hand, or had a foosh (fall on outstretched hand) though that more usually results in fractured arm. Or he might have been in a fist fight.
Impacted base index (finger) means it has been pushed down and impacted on bones behind it
Bennett's fracture is fracture at base of thumb, not seen all that often to my recollection.
Dawn M
EDIT; first word of last line is vide = Latin for see, so see request attached, as I see Colin has already said.