Double Jointed Elbows and being a PO

Just found out my son is double-jointed (hypermobility) in only his elbows. He is a High School PO.

Can’t find much online about this…

Anyone have any experience with this?

TIA

Perhaps the fastest fast-baller of all-time had some degree of hyper-mobility (in his elbow or wrist):

New Britain, CT: Home of the World's Fastest Fastball