Instruments

Authors: Thomas Givskov Sørensen, Magnus Balslev Avstorp MD, Ahmad Makki MD and Gete Toft

Introduction

In this chapter you will learn how to setup the operating microscope, microsurgical instruments, the ergonomics and tremor control in microsurgery.

Setting up the microscope

The operating microscope needs to be adjusted to fit the surgeon prior to the procedure. It is important to optimize working position to reduce strain on the surgeon and enhance working conditions.

The surgeon should be in a comfortable chair, relaxed, with his back straight, feet flat on the ground, and with the microscope in eye level. The operating microscope rests on an arm allowing the height of the microscope above the surgical field to be adjusted and bringing the surgical field into focus. The eyepieces may be adjusted in interpupillary distance, diopter settings and focal length.

Microscope setup

Demonstrated on a Zeiss OPMI pico operating microscope

The eyepieces on the operating microscope usually have a 10X or 12.5X magnification.

Adjusting the interpupillary distance by turning the knob. Normally it is between 65mm and 75mm.

Adjusting the diopter for each eye to accommodate for ant refraction anomalies the user might have by turning each eyepiece.

Shifting between the objective lenses. Lenses vary from 0.4X to 4X. As the eyepieces usually have a 10X or 12.5X magnification the operating microscope will magnify from 4-40X or 5-50X. For free flap surgery objective lenses with a focal length of 250 mm is most commonly used making the working distance 250 mm.
The Focal length can be adjusted by turning the knob on the varioscope in the bottom.

Microsurgical instruments

Needle driver

The needle driver is held in the dominant hand and is used for handling the needle while suturing under the microscope. Alternatively, the needle driver can be utilized as forceps for tissue handling or as a probe when in a closed position. The needle driver is spring handled and comes equipped with or without a locking mechanism (Cremaillére).

Adventitia scissors

The adventitia scissors have pointed tips and straight blades. They are used for fine dissection on high magnification, cutting blood vessels and trimming sutures.

Hold the scissors using a pencil grip, resting the wrist and hand comfortably on the table.

Dissecting scissors

The dissecting scissors have blunt tips and curved blades. They are primarily used for microsurgical dissection close to vessels or nerves. Due to the blunt tips, the scissor can be used as a probe while in a closed position. The scissors are spring handled, and therefore open automatically, as tension is released.

Jewelers forceps – straight and angled

The microsurgical forceps or ”jewelers forceps” serves multiple purposes. In general, the tip can be either straight or angled. They are held in the non-dominant hand of the surgeon and are used to present the tissue, create traction, and support the tissue while suturing. They can be used for handling the suture while knot tying, and the angled forceps may even be used as a needle driver for small needles (sizes smaller than 9/0). Two pairs of forceps may be utilized for gentle dissection of connective tissue.

Holding the forceps using pencil grip. Position open.

Holding the forceps using pencil grip. Position closed.

Vessel dilator

The vessel dilator is used to passively stretch the vessel wall to increase the caliber and minimize the risk of vasospasm. The tip is slim, exactly parallel, polished, and rounded allowing the vessel wall to be stretched with minimal damage.

Acland vessel clamp

The vessel clamps are used to arrest blood flow in arteries or veins while transferring the flap and performing the anastomoses. The clamps have flat surfaces and comes in different sizes for optimal closing force and minimal trauma to vessel walls. The clamps can be singles, doubles parallelly mounted on a slider, or with a built-in frame for suture holding.

Holding the vessel clamps – position open – View from the top.

Holding the vessel clamps. Position open.

Clamp applicator forceps

The clamp applicator forceps are made specifically for the safe application of the Acland vessel clamp. The tips of the forceps are designed to fit the posterior edges of the clamp.

References

C. Lakhiani, S. M. Fisher, D. E. Janhofer, and D. H. Song, “Ergonomics in microsurgery,” J Surg Oncol, vol. 118, no. 5, pp. 840–844, 2018, doi: 10.1002/jso.25197.
E. Belykh et al., “Systematic Review of Factors Influencing Surgical Performance: Practical Recommendations for Microsurgical Procedures in Neurosurgery,” World Neurosurg., vol. 112, pp. e182–e207, 2018, doi: 10.1016/j.wneu.2018.01.005.
K. M. Fargen, R. D. Turner, and A. M. Spiotta, “Factors That Affect Physiologic Tremor and Dexterity during Surgery: A Primer for Neurosurgeons,” World Neurosurg., vol. 86, pp. 384–389, 2016, doi: 10.1016/j.wneu.2015.10.098.