That's not really how consent works, at least not in the US. You typically give consent for the operation, not for every individual procedure that's done in the operation. A lot of the times you don't really know what's going to be needed to be done until you have the patient opened up, so the provider has a lot of leeway to operate as they see fit.
How quickly can it absorb?
Depends on the individual and what bone we are talking about. Though that's quite a lot of bone to dissipate, so my guess would be that it's a fairly old injury.