This surgical amputation saw (also called bone saws) dates to the 1700s based on its structurem where the screw that holds the blade is located, and the presence of a bump so to speak at the top. I can see no maker mark which is typical for 1700s amputation saws so you need to do your homework to ensure you are not buying a fancy carpenter caw.
This saw measures 16 inchs in length and is in fine condition.