Surgical instruments

Chapter 2: Surgical instruments

Brian R. Brenner, Tyler Ericson, Priyanka Singla, Lynn Kohan

Common instruments used during surgical procedures of the spine

In general, vertebrae get larger cranial to caudal; thus as a general rule of thumb instrument size for spine procedures increases in size from cervical (C) spine to lumbar (L) spine. The purpose of this chapter is to orient the proceduralist to common surgical equipment encountered for basic surgical skills.

Of note, specific tools for the accomplishment of various fusion procedures will not be covered in this chapter. The tools that are unique to the company-made kits will be further discussed in the chapters covering those specific procedures. We have grouped instruments according to their use.

Instruments used for making an incision


Scalpels are used for general skin incision. They have two parts—blade and handle. The belly of the blade is used for making the incision.

Scalpels come in various sizes, such as the #10 blade shown in Fig. 2.1. There are other-sized scalpel blades not referenced in this text.

Scalpels are very sharp instruments and cause injury if not handled appropriately. Safety precautions can prevent accidental laceration of the hand or body of the provider. Some of these include attaching the blade to the handle with the help of a forceps, marking the skin before incision, and holding the scalpel with the dominant hand. The scalpel is used to make superficial incisions through the epidermis and dermis partially into the subcutaneous tissue below.1

Countertraction of the skin, either with the operator’s other hand or from an assistant, can be helpful in achieving a straight smooth cut in one motion.1 A sharps safety tray (Fig. 2.2) should always be used to pass sharp instruments between the surgical field and the scrub nurse’s Mayo stand. This aids in prevention of accidents and stick injuries with sharps and needles.1 It is common courtesy to use clear language such as “sharp back,” “passing sharp,” “knife down,” or “needle down and/or protected” when passing or moving instruments that have the potential to cause injuries.

Blade sizes

The #10 blade is the most commonly used blade for skin incisions. Fig. 2.1 shows a standard #10 blade with a #3 handle.

Instruments used for dissection

Once initial incision has been made with a scalpel, hemostasis is achieved with electrosurgical instruments. Dissection of tissues to adequately expose the structures of interest can be accomplished with electrosurgical, blunt, or sharp tools.


When an electrical current encounters a substance with resistance, heat is generated. Because all body tissue has an inherent resistance, this principle can be used to selectively cut, desiccate, fulgurate, or coagulate tissue. Electrosurgery is the utilization of a high-frequency alternating current to generate heat at a particular tissue for a desired surgical effect.2

Types of electrosurgery

Electrosurgery can be either monopolar (Fig. 2.3), or bipolar (Fig. 2.4),3 depending on the path the current takes.

Fig. 2.4Various bipolar electrosurgical instruments.3 Source: (Published with permission from Ustatine RP, Pfenninger JL, Stulberg DL, Small R. Dermatologic and Cosmetic Procedures in Office Practice. Elsevier; 2012.)

In a monopolar system, there are two electrodes. One is the active surgical instrument and the other is a dispersion pad, which must be located far from the surgical site and have a large surface area. Inappropriate placement or inadequate surface area of the dispersion pad can result in severe burns.4,5

In a bipolar system, the electrical current flows between two electrodes, which are both located on the surgical instrument (forceps, scissors, graspers).

Advantage of bipolar electrosurgery

With a bipolar system there is less unintended heat spread. Bipolar electrosurgery is also better at providing hemostasis because the tissue is compressed between the two electrodes and then heated. A schematic of the dispersion of energy in a bipolar versus monopolar electrosurgical system is shown in Fig. 2.5

Fig. 2.5General schematic of a monopolar versus bipolar electrosurgical systems.2 Source: (Published with permission from Hay DJ. Electrosurgery. Surgery (Elsevier). 2007;26(2):66-69.)

Modes of electrosurgery

Electrocautery can be used in cut or coagulation mode. Current frequency, time of activation, and the use of continuous or intermittent waveforms can be changed to adjust the amount of heat generated during electrosurgery.

Cut mode uses a continuous, low-voltage current that forms a more concentrated area of high current density that results in a more rapid heating of tissue. The alternating current causes intense vibration and heat within the cells, causing them to vaporize, effectively cutting the tissue.5 When using the cutting mode the electrode should be held close to the tissue, but not in direct contact. Despite being called cut mode, this mode is also effective at coagulation and generally results in less collateral thermal injury than coagulation mode.6

Coagulation mode utilizes an interrupted, high-voltage current over a larger surface area. Because the current is interrupted, the tissue has time to cool, resulting in coagulation rather than vaporization.4 A downside of the higher voltage is more tissue damage and more thermal spread, increasing the risk of complications.

Because cutting mode is also effective at coagulation but with less risk of complications, many recommend only using coagulation mode when dealing with highly vascular tissue or tissue with poor conductivity such as adipose tissue. A common mono- and bipolar wall unit with corresponding cut versus coagulation functions is shown in Fig. 2.6.

Fig. 2.6Mono and bipolar wall unit illustrating cut versus coagulation controls that are common to many electrosurgical units.3 Source: (Published with permission from Ustatine RP, Pfenninger JL, Stulberg DL, Small R. Dermatologic and Cosmetic Procedures in Office Practice. Elsevier; 2012.)


Complications from the use of electrosurgery are relatively common, with approximately incidents 2 to 5 per 1000 procedures.4,5 The most common adverse events are thermal burns and hemorrhage, with fire being a rare complication. The use of higher power settings with higher voltage causes more thermal spread and tissue damage. Severe burns can occur if the dispersion electrode pad becomes partially detached, minimizing the effective surface area and focusing the current on a smaller portion of the skin. In patients with electrical implants, it is ideal to use a bipolar device and to assess the function of the implant after surgery.

Tissue dissection

Blunt dissection moves tissue planes without cutting, reducing bleeding risk and chance of incising important surrounding structures. Overly forceful blunt dissection should be limited to decrease chance of wound complications such as seroma formation, infection, and prolonged healing.

Sharp dissection results in less general tissue trauma at the cost of increased bleeding, which may be problematic. This can be mitigated by utilization of electrosurgical dissection in the cut mode.

Overall, some combination of gentle blunt, sharp, and electrosurgical dissection will need to be utilized to achieve the safe desired exposure.1


Scissors are used for cutting and dissection of various tissues. They can be either sharp or blunt. The shape and size of this instrument is based on its intended function and purpose. A few commonly used scissors for interventional pain procedures are listed here. This is not a complete list and is intended to familiarize the reader with this class of instrument.

Metzenbaum scissors

These scissors have a number of variations. They can have blunt or sharp tips and can either be curved or straight. Applications include blunt dissection of tissue or cutting of tissue for dissection. Metzenbaum scissors are smaller than the similar Mayo scissor (Fig. 2.7). The benefit is a more equal cutting and dissecting tip in relation to the length of the shaft, which gives the operator more finite control of the instrument in small or anatomically vulnerable areas. The disadvantage is smaller size and less force generation for cutting and dissecting of stronger tissue such as muscle or fascia.1

May 21, 2023 | Posted by in PAIN MEDICINE | Comments Off on Surgical instruments
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