https://healthyy.net/low-testosterone/benefits/testosterone-and-bones

Hope this helps. Here's a fun fact: estrogen fuses to the ends of the bone, that is why fat people in cartoons and real life are typically short.

@Fred, I just read it

Ever notice how how fat people usually have sleep apnea, are bald/balding and have pretty bad cfd?

What would happen to bones if someone just jacked you up with testosterone, would your bones get thicker/bigger?

That's a hard question to answer...for me at least. 

The answer resides in our bones. When we are in our adolescent years our bones grow by the signal of HGH and a secondary hormone product known as IGF-1. When HGH reaches a region at the ends of the long bones called growth plates or epiphyseal plates it stimulates new layers of bone to be added. 

Judging by this answer(not from me) hgh is the one responsible for this. If you're looking to get thicker joints just carry exercise them, Elliot Hulse has a video on this and there are loads of expert advice from other people like him. Watch the vid for some details and clues that can answer some questions. 

https://www.youtube.com/watch?v=1-qb79MSJrg