erectile dysfunction

My boyfriend fell while running and broke his femur before hitting the ground in July.  He got surgery, and had a titanium rod inserted into his right thy.  The break was about half way down his femur.  He has not been able to maintain an errection since, and it has been about three months.  He gets somewhat hard, but it does not last or get completely hard.  Is this from the surgery, the impact, neurological? We have no idea and dont know where to begin with asking questions to the surgeon