Surgical scalpels come in a variety of shapes and sizes, and often the term scalpel and surgical knife are used interchangeably, but there is a difference. The difference between a knife and a scalpel is that a scalpel has a reusable handle, but a disposable blade. And a knife is both a reusable handle and blade combination.
Each blade has a specific purpose. A number 10 blade is for large incisions, a 15 is for small incisions, a 12 is a sickle knife made for removing kidney stones or tonsils. And then the 11 blade is a puncture or spear point knife that can be used to drain abscesses or to gain access to a duct or blood vessel.
The 10, the 15, and the 12 and 11 will all fit on a number 3 knife handle, a number 7 knife handle, and a number 9. If the blade is a size 20 or higher then those blades go on a number 4 knife handle. The blades are much bigger and the opening in the blade is much bigger, so the handle has to be bigger.
To load a blade onto a knife handle, the first step is to make sure we have the orientation of the knife handle correct. I can read the number on the knife handle and I have the grips facing up. This cutout where the blade is going to fit has got to be face-up. To do it the other direction, the blade won't be able to fit on.
So with the knife handle and the proper alignment, I'm going to take my needle driver or needle holder and apply it on the dull side of the blade above the opening. Now, the tip of my knife handle is going to come in through the bottom, and I'm going to introduce it where the opening goes from wide to narrow, and I'm going to slide it back. Once the blade is on, I could check it, I could even turn it over and tap it to make sure that it's incapable of falling off.
To remove this blade, I'll go below the opening, grab the blade and only the blade, very gently lift up, and push off with my thumb, and the blade comes right off.
It does not matter what size blade we're applying, the procedure is still the same. On the dull side, grab the blade above the opening, introduce the tip from the bottom, put the tip where we go from wide to narrow, and slide it right on, you feel and hear the click, we can turn it over and tap it, make sure that it is good and secure. Once again, to remove the blade we'll apply the needle holder underneath the opening, lift up slightly, and push off with our thumb, and it comes right off. If we feel like we're in a bind or we're pushing too hard, stop what you're doing in readjust.
All of these blades, except for the 20 and higher will fit on a number 3 or a number 7. The most common use of a number 7 knife handle is with a number 11 blade to do a puncture or an arteriotomy. Once again, we put the needle holder above the hole on the dull side and we will introduce the tip of the knife handle right into the opening where we go from wide to narrow and we lock right on. We feel the click, we can tap it to make sure it's not going anywhere, even pull on the blade. And once again to remove it, we will apply the needle holder below the opening, lift up barely, and then push off with our thumb, and off comes the blade.
The number 12 is done the same way. From underneath the blade we introduced the tip from where it goes from wide to narrow, and it slides right on. It's good and secure. To remove it, we will grab the blade and only the blade underneath the opening, barely lift up, and push off with our thumb, and it comes right off. If we're having trouble doing that, stop what you're doing and readjust.
Larger blades, size 20 and up, are for large incisions, autopsies, things like thoracoabdominal incisions. You'll notice that the opening in the blade is much larger. Although the number 4 knife handle and the number 3 look similar, they are not. Only blades 20 and higher will go on a number 4 knife handle. But the same process applies. On the dull side, place the needle holder above the hole. From underneath the blade, introduce the tip right where we go from wide to narrow, and slide right on, and it locks in place. It's good and secure. We could turn it over and tap it, make sure it doesn't fall off, and we're ready to pass it. To remove the blade, just like in the other sizes, we put the needle holder on the blade and blade alone, barely lift up, and then push off with our thumb, and off it comes. It ought to go very smoothly. If it doesn't, stop what you're doing and readjust.