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Introduction

The era of microsurgery, which followed the introduction of ultrafine, nonreactive sutures, precision surgical instrumentation, and improved optical magnification, led to digital replantation, free tissue transfer, vascularized bone grafting, and other procedures. This chapter provides basic information about microsurgical procedures, techniques, and the equipment needed to perform them.

Microsurgical Instrumentation

Because of the exacting requirements of microsurgical procedures, high-quality instrumentation is crucial. Microsurgical tools require specialized storage conditions and individual cleaning, as well as regular inspections, repair, and replacement to ensure that they are ready for use by the surgical team.

A basic set of instruments should include microsurgical forceps (4, 5A), vessel dilating forceps, curved scissors, straight scissors, and vascular clamps (single and double for both arteries and veins). For more advanced procedures, surgical background with color contrast, microsutures, and microirrigation syringes are needed. Some complex cases may be facilitated by custom instruments.

Methods of Magnification

Operating loupes—easily used and customized to each surgeon—work well for procedures in which lower levels of optical magnification (2.5–6.5×) are sufficient. The disadvantage of loupes is that magnification and depth of field are fixed.

An operating microscope is necessary for surgeries that require higher levels of magnification. This larger instrument provides exceptional image clarity and vibrant light. The operating microscope can be set up for use by a single operator or two surgeons. Newer microscopes have the capability for in-room televised display and recording of the operation. However, operating microscopes are more cumbersome to use than loupes, are expensive, and require significant maintenance.

Procedures often done with loupe magnification include:

  • Pediatric hernia repair

  • Hypospadias

  • Discectomy

  • Coronary artery bypass graft

  • Arterial bypass graft using reversed saphenous vein interpositional graft

  • Larger nerve repair

  • Blepharoplasty

  • Tendon repair

Procedures often done with use of the operating microscope include:

  • Replantation

  • Free tissue transfer

  • Hand aneurysm resection and repair

  • Smaller vessel repair (digital artery)

  • Smaller nerve repair (digital nerve)

  • Vascular repair

Psychomotor Skills Training

Like most surgical skills, precision techniques for microsurgery are best taught in a laboratory setting; standardized instruction is available in a number of centers. Typically students begin with simple methods for arterial repair. As their skills improve they advance to more difficult procedures, such as interpositional vein grafting. Because live animals are used, surgeons obtain direct feedback on the outcome. The significant learning benefit from this method is that students know their success rate for various procedures prior to taking them to a clinical setting.

Surgical Setup

The setup for each case varies, but planning the procedure is time well spent. For most orthopedic and hand surgeries the microscope should be set up for “opposing” use, i.e., surgeon and assistant across from one another. For some ENT procedures, the surgeon and assistant may be oriented at right angles.

Suture Materials

Surgeons generally prefer 7–0 to 11–0 monofilament, nonabsorbable sutures. Our preferences are for nylon and prolene.

Procedure for Vascular Repair

Dissection/Preparation

For arterial repair in the limbs, regional or general anesthesia can be administered. The initial dissection should allow both proximal and distal control of the vessel. Usually this dissection is done with a broad pneumatic tourniquet inflated to a pressure that is 100 mmHg above the patient’s systolic blood pressure.

End-to-End Arterial and Venous Repair

The segment for repair (Fig. 20.1) is dissected free and the arterial ends are sharply trimmed using optical magnification. Using straight, sharp scissors, cut the vessel at right angles to the long axis of the artery. Gently dilate the artery, clean the artery’s interior of clot, and irrigate with a heparinized saline solution. With the tourniquet deflated, confirm satisfactory inflow and then apply a vascular occlusion clamp to the proximal artery. The two arterial ends are then positioned within the double clamp, leaving a small gap. For visual contrast, place a colored plastic background or suction mat behind the artery.

Figure 20.1.
figure 1

Vascular segment is dissected free.

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Suture the artery using an interrupted technique, everting the vessel edges. Place the initial two sutures 180° apart; then place the third suture halfway between them (Fig. 20.2). Each subsequent suture should again be placed halfway between the adjacent sutures until the vessel repair is complete (Figs. 20.3 and 20.4).

Figure 20.2.
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Interrupted suture technique.

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Figure 20.3.
figure 3

Intermediate suture placement.

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Figure 20.4.
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Back wall of sutured vessel.

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Turn the vessel over (180°) in the clamp. By opening the back wall with forceps, the surgeon can inspect the first half of the repair for accuracy. Again irrigate the vessel with a heparinized saline solution.

Assessing Patency

Next, remove first the distal clamp, then the proximal clamp. Inspect the repair for leakage and insert additional sutures as necessary. The surface of the vessel can be irrigated with Xylocaine to facilitate vessel dilation.

Begin assessment of patency of the repair. Inspect the distal color and capillary refill and feel for a distal pulse. Use a sterile Doppler to listen to the flow and perform a “milking test” of the repair: use two smooth forceps and place them side by side over the artery several centimeters proximal to the repair; occlude the artery with both forceps; gently slide the distal forceps distally across the repair site to a position well distal to the anastomosis so that the artery is “milked” flat. Release the arterial forceps proximal to the repair site and document anterograde flow that crosses the anastomosis in the artery. When possible, design a wound closure that places normal (or nearly normal) skin over the site of vascular repairs.

Procedure for Nerve Repair

For nerve repair, clamps and positioning devices are usually not needed. Primary peripheral nerve repair is done using an interrupted epineural suture method. For repair of traumatic injury, the proximal and distal ends of the artery are carefully identified and then mobilized by longitudinal dissection. When the nerve ends are mobilized sufficiently for end-to-end repair, the nerve must be oriented. Orientation will be facilitated by:

  • A general working knowledge of the internal topography of the nerve

  • Epineurial surface vessels that may be aligned in the repair

  • Inspection of the internal fascicular array of the nerve

With the nerve oriented, the surgeon begins the repair by placing two sutures 180° apart in the external epineurium. Additional sutures are placed to bisect the distance between adjacent sutures until the repair is complete (Figs. 20.5 and 20.6).

Figure 20.5.
figure 5

Nerve is oriented and first sutures are placed.

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Figure 20.6.
figure 6

Intermediate sutures are placed.

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Recommended suture gauges for specific nerves are as follows:

  • Median, ulnar, and radial nerves: 7–0 to 10–0

  • Common digital and proper digital nerves: 9–0 to 10–0

Procedure for Neuroentubulation

Neuroentubulation is an alternate method of nerve repair. It positions the transected nerve ends within 2–3 mm of each other, then allows repair to occur in the protected environment of the nerve tube. Previously, neuroentubulation was done with autogenous vein. There are now a number of commercially available devices for nerve entubulation. Initial dissection mobilizes the cut nerve ends. The cut ends are freshened with a sharp, straight scissors. With a suture method, the ends are advanced into the tube (Fig. 20.7).

Figure 20.7.
figure 7

Neuroentubulation.

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Alternatively, the tube may be split, the nerve ends are laid into the tube (Fig. 20.8), and the tube is sutured closed with a running suture. The tube diameter should be slightly larger than the nerve to allow for postoperative edema in the nerve.

Figure 20.8.
figure 8

Tube split, nerve ends laid in, tube closure with running suture.

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Summary

Optical magnification and other improvements in instrumentation have expanded the surgeon’s ability to treat a wide variety of difficult conditions. Appropriate tools and training enable the surgeon to repair vessels of less than 1 mm satisfactorily.