Bent rod

One day the car suddenly started missing and emitting white smoke from the exhaust pipe. The problem was a fuel injector stuck open. It was replaced. When I picked up the car it was making a tapping noise in the engine which it was not making before. The mechanic told me that it was a bent rod and I needed a new engine and that would cost $4,200.00. I said I would get more estimates and get back with him. Another mechanic tells me that a fuel injector would not cause a bent rod and it didn’t sound like a bent rod to him. His guess was that something was dropped into the piston while changing the fuel injector and the piston was damaged. The car is running fine except the traction control is not working and it is shifting a little rough. My question is, can a faulty fuel injector cause a bent rod?