Wow, sorry that happened to you and I hope you're doing well now. I can't believe that after the accident and prior to surgery that you had the presence of mind to call to cancel your ticket!

But isn't the solution here to purchase travel insurance instead of a refundable ticket? I suppose to some degree that would depend on the cost comparison, but a good travel insurance policy would have reimbursed you for the flight, plus it would have provided you with health insurance coverage in the US. It would have negated having to call the airline prior to your operation, plus the ask to being discharged early to save on costs.