Ouch... Wishing you a speedy recovery!
I think situations like that are why I don't carry assisted-opening knives or auto-knives. I own a few of them to round out my collection, but I don't feel comfortable carrying them. An employee of mine had his assisted knife open up in his front pocket. It cut a hold in his pocket and boxers. I'm guessing it could have been much worse!
Assisted opening knives that have to be opened with the thumb stud make me really uncomfortable. It is impossible to have a firm grip on the knife as it opens and blade snapping open makes the knife want to slip out of my hand. I also feel that the blade is going to snap open and I will slice my thumb off as I continue the motion of pushing the thumb stud. The only exception is flipper styled knives which allow me to have a better grip and open the knife with my index finger. The problem with those is they also tend to open up accidentally if the flipper gets pushed.
My issue with auto-knives is that many of them have safeties that can be accidentally activated or difficult to deactivate quickly. Many of them also require the release button to be depressed completely. I have a Benchmade and Microtech that are both like that. Auto knives are also hard to close with one hand.
I have gotten so used to opening my manual knife that I can do so as quickly as an automatic knife or assisted knife. I usually carry a Benchmade 710 which uses the Axis lock. It is easy to flick open but will not open accidentally. It is also very easy to open and close one handed.