Basic Instrument Use Course Notes: Scissors Introduction to Scissors Blades Surgical scissors are instruments that can be used Scissors have two blades: the inner blade and the outer for both cutting and dissection. The three main blade. The inner blade is the side of the blade that faces applications for scissors include: the opposing blade and is visible when the instrument is open. The outer blade is the side of the blade that can 1. Sharply cutting soft tissues be seen when the scissors are in the closed position. 2. Bluntly spreading soft tissues during dissection The cutting edge of the blade is located along the inner 3. Cutting suture or bandage materials. side of the blade. Scissors offer several advantages over scalpel blades, The spine of the blade is the thickest part, and it is such as the ability to precisely cut loose soft tissues, located opposite the cutting edge. Finally, the end of especially deeper tissues that cannot be held under the blade region is called the tip or point of the scissor, tension. Another advantage is that scissors allow for and is the area that tends to receive the most wear. superior depth control during dissection. However, Scissor tips vary in configuration and they can be blunt, scissors have one significant limitation; they require an sharp, or a combination of sharp and blunt. opening in the tissue to insert the lower blade. Scalpels, on the other hand, can be used to incise through an Types of Scissors intact tissue surface. Despite this limitation, scissors Scissors come in many shapes and sizes, most are important surgical instruments and are frequently bearing the name of the surgeon that developed the used during surgery. instrument. Some names are descriptive, like the sharp-blunt scissors. Others are named for the type In this module we will examine the common types of of procedure they are often used in, such as tenotomy scissors used in veterinary surgery; how to properly scissors or bandage scissors. In this topic, we will focus grip, use, and pass scissors; the four cutting and on the main classes of scissors used most commonly dissection techniques for scissors; and the surgical in veterinary surgery. Learn more about each type of applications for scissors. scissor shown here below. Anatomy of Scissors Mayo Scissors Handle Mayo scissors are characterized by a smaller blade- All scissors feature a handle, where the scissors are to-handle length ratio. These stout scissors are often held during cutting or dissection. The handle has used for cutting tough tissue or suture. Mayo scissors two rings, called the finger hole and the thumb hole. are available in both straight-bladed and curved- Scissors are made to work most effectively for a bladed styles. The straight-bladed Mayo scissors are specified right- or left-handed surgeon. Many left- designed for cutting tough tissues near the surface of handed individuals learn to use right-handed scissors the body. Curved-bladed Mayo scissors allow for better with their left hands, but this can be ineffective and visualization during deep tissue awkward. Left-handed scissors are available for left- dissection. handed surgeons who prefer them. Metzenbaum Scissors Shanks Metzenbaum scissors are characterized by distinctive, Scissors have a set of articulating blades, each of which long, slender handles and shorter blades. These are attached to the handle by the shank. The shanks scissors come in a variety of lengths and are used to can either be of equal length or be unequal in length cut and dissect delicate soft tissues. Metzenbaum by an amount known as an “offset.” Surgical scissors scissors should never be used for cutting sutures or usually have shanks of equal length. The shanks and tough tissues. Because of their specific function, they the blades meet at the pivot screw. The pivot screw is sometimes are called Metzenbaum dissecting scissors. responsible for holding the blades together at a specific tension. 1 Tenotomy and Iris Scissors tough tissue. In addition, straight scissors can provide Tenotomy and iris scissors are very small dissecting a more precise straight cut compared to their curved scissors. Iris scissors have a fine, pointed tip and are counterparts. These characteristics explain the normally reserved for the most meticulous work. common practice of using straight, stout, Mayo scissors Tenotomy scissors are similar in size and purpose, but to open the tough linea alba in midline abdominal have blunt tips that push tissues aside rather than approaches, where it is important to avoid straying piercing and damaging them. These scissors are used to paramedian into the rectus muscles. dissect around delicate neurovascular bundles, and for purposeful cutting of vital smaller structures, such as Blunt-tipped scissors are favored over sharp- the ureter or urethra. tipped scissors in situations where dissection is being performed around important structures. Wire Cutting Scissors The advantage of the blunt tip is that it is less likely Wire cutting scissors are characterized by short, stout to get caught in tissue. Additionally, blunt-tipped blades with a sharp, angled tip. One side has a serrated scissors separate tissue without damaging nearby blade, while the other side has a smooth blade. On the neurovascular structures, especially when probing or serrated side, the blade often has a small notch at the bluntly separating connective tissue layers. base to help hold wire in the blades during cutting. Some scissors possess a serrated edge. These edges Lister Bandage Scissors have fine notches, like teeth on a metal saw, which help Lister bandage scissors have angled, serrated or prevent tissue from slipping out of the blades. Serrated unserrated blades and an angled, blunt tip. Bandage scissors are useful for cutting slippery tissue, or for scissors are often found in first aid kits and have firm, tough tissue such as the ear canal, which tends numerous uses that make them valuable. Their three to slide out of the blades during scissor cuts. Plastic mains functions include: trimming bandages to custom surgeons often choose serrated curved scissors in size, cutting through gauze, and helping to remove order to create accurate and conforming skin incisions. patient bandages. For this last purpose, the angled blades are extremely important, since they angle away Some scissors, like the Super Cut™, Microsharp, and from anything beneath the cutting surface. This helps SureCut scissors, possess specialized blade edges. keep the scissors away from the skin, preventing injury These scissors have uniquely ground edges where during bandage removal. The blunt tips also minimize one edge has microserrations and the opposing edge the risk of piercing the skin, which might occur with is honed sharp. This combination ensures precise, sharp tipped scissors. fine, and non-crushing cuts that minimize trauma. The Super Cut™ patterns also cut efficiently when used Selecting Scissors in most angles without changing hands or turning the scissors over. Metzenbaum, Mayo, and iris scissors are In addition to main families, scissors are classified all usually supplied with Super Cut™ blades. Keep in according to a number of other differentiating mind that although Super Cut™ scissors cut soft tissues characteristics. Features such as straight shanks, very well, they dull easily, especially when used to cut curved shanks, or serrated edges greatly impact the tough tissue or sutures. Super Cut™ scissors are readily suitability of the instrument for cutting and dissection identified by their black ring handles. purposes. In this topic, we will explore a range of scissor variations and the surgical applications for which they Some scissors have tungsten carbide inserts on are best suited. the blade edges. Carbide is a very hard metal that maintains a sharp edge much longer than stainless Curved scissors are often chosen when the tissues steel, reducing the frequency of sharpening. However, need to be cut in a smooth curve. Another advantage unlike carbide tipped needle holders, the carbide of scissors with curved blades is that they offer 30–40 inserts in scissors cannot be replaced. Carbide-tipped degrees more directional mobility than straight scissors are readily identified by their gold ring handles. scissors. When working in remote recesses where horizontal cutting is needed, curved scissors also Gripping, Using, and Passing Scissors allow for better visibility of the tissues being cut, when compared to straight scissors. The most common manner of gripping scissors is to insert the tip of your thumb on your dominant hand Straight scissors provide better mechanical advantage, into one ring and the tip of your ring finger into the making them superior to curved scissors for cutting other. The rings should rest between P2 and P3, 2 but do not insert your fingers further than the last How Scissors Work knuckle. Inserting the fingers more proximally reduces Most surgeons favor scissors over scalpels when the motion and action, and handling becomes awkward cutting flaccid tissue or when dissecting close throughout the range of motion of the wrist. The index to important structures. The reason behind this finger is placed on the shanks, close to the hinge, and preference is that scissors are good at stabilizing tissue, provides stability by supporting the sides of the shank. allowing for a more accurate cut. To understand why In the scissors grip, the positions of the thumb, index, this is so, let’s take a closer look at the physics behind and ring fingers form a triangle, giving rise to the term how scissors work. “tripod grip.” The greater the distance between these fingers, the better control the surgeon has with the Scissors are designed so that three force vectors scissors. are simultaneously used in cutting. The three forces include closing, shearing, and torque. The forces are As with all ringed instruments, scissors should not be transferred from the surgeon’s hand to the shanks, held using a grasp like a “bear claw” or mitten.