Fortunately, they were able to sew her snap back on so the scar didn't show, and she got a bad concussion, but I have to conclude she came out of that rather lucky.
As an aside, Admiral Chester Nimitz and Admiral Isoroku Yamamoto, foes in WWII, were both missing fingers on their left hand.
Yamamoto lost two of his fingers on his left hand in the Battle of Tsushima in 1905 against the Russians when the Mikasa (flagship, commanded by Admiral Togo) was hit by Russian shells.
Nimitz lost his ring finger in 1926 when he was giving a tour to some delegation of the diesel submarine he was on. He was the Navy's leading expert on diesel propulsion, and was in coveralls giving the tour, and when he pointed at an exposed gear while speaking to the delegation, the tip of the leather glove got caught in the gears and sucked his hand in.
It crushed his entire finger up to his wedding band which jammed the gears and saved him from being drawn into the gears and maimed or killed, but he lost the finger to just below the joint. He was very self conscious about it, so it was a surprise to me that it showed in his official portrait: