My friend had her miniature poodle in Agility, and he did this. So it doesn't matter if he is overweight or not, it is how they land, and can happen to any of them, in theory.

Teddy was 2 years at the time. She went with the vet's recommendation for the surgery. She said keeping such a young active pup calm during the recovery was a bit of a challenge, but he healed up fine. He is 3 years old now. He is no longer in Agility, and both of them miss that.

Wait for the xrays, listen to what the vet says and recommends. Take notes so you can think about it at home, if need be.

Best wishes!