12.1
Introduction of 3D exoscopes in reconstructive microsurgery
Exoscopic technology was first introduced in free flap reconstruction in 2017. In particular, Piatkowski et al. described their experience in breast reconstruction with a bilateral deep inferior epigastric perforator flap. The authors highlighted the lower depth of field compared to the operating microscope and the loss of resolution of the image at higher magnification. However, they believed in the potential of the exoscope in substituting the operating microscope with some adjustments in the future, especially underlying its versatility and ergonomic advantage.
During the last 2 years, several papers have been published reporting the feasibility of head and neck reconstruction using the exoscope. Ichikawa et al. reported the use of the VITOM 3D exoscope in two cases for head and neck reconstruction with a free anterolateral thigh flap transfer. De Virgilio et al. previously described the technical feasibility of microvascular anastomoses in 10 consecutive patients. The ORBEYE 3D exoscope (Olympus, Tokyo, Japan) was also used to perform three head and neck free flap reconstructions by Grammatica et al. These papers allowed to better define the advantages and disadvantages of this system if compared to the operating microscope. Even if a direct comparison between these two systems is not available in the current literature, the exoscope demonstrated a high level of reliability and quality in terms of visualization and magnification of the surgical field.
The main application of the exoscope in head and neck free flap reconstruction is during the execution of microvascular anastomoses. However, the 3D vision and the modular magnification allow for augmented visualization also during free flap harvest and inset. The present chapter aims to provide a summary of the applications of the exoscopic technology to free flap head and neck reconstruction. In particular, the authors’ experience is described to analyze the advantages and disadvantages of the exoscope in the execution of microvascular anastomoses.
12.2
Operating room set-up
As already mentioned in Chapter 1 , the small size of the 3D camera and the slim holding system allow for a less cumbersome placement of the system if compared to the operating microscope. No interferences with the surgical field should be guaranteed during the procedure, and the main surgeon and the scrub nurse’s movements should not be limited by the system. The exoscope is less cumbersome than the operating microscope, and it could be easily placed at the patient’s feet during the microvascular anastomoses. As a consequence, the scrub nurse can position itself at the patient’s head, without interfering with the screen visualization. The assistant surgeon can position itself next to, or in front of the main surgeon. However, in the latter case, a secondary screen should be placed for the assistant to achieve an adequate view of the surgical field. Other operating room (OR) members, such as students, should position themselves behind the main surgeon to maintain a perpendicular view of the screen. An example of the OR set-up during microvascular anastomoses is shown in Fig. 12.1 .
If the operating exoscope is used during the free flap harvest, the OR set-up would be surely more complex. Free flap reconstruction is usually performed in the same timeframe by two different surgical teams, except for some centers. The exoscopic system could be easily placed at the patient feet if the free flap is taken from the lower extremities (e.g., fibula free flap or anterolateral thigh flap), while it is more difficult to find the right position during upper extremities free flap harvesting (e.g., radial forearm free flap) without interfering with the head and neck tumor resection team.
12.3
Free flap harvest
Although an increased magnification is required to adequately perform a microvascular anastomoses due to the low diameter of vessels, the free flap harvest could be easily performed under direct vision. Surgical loupes are widely used to enhance the surgical field magnification, improving the ability to perform tissue dissection. Operating microscopes are rarely used to perform these surgical steps due to the high dimension of commonly used microscopes. On the other hand, the exoscope is less cumbersome than the operating microscope, and it could be used during free flap harvest as already mentioned earlier ( Fig. 12.2 ).
Magnification of the surgical field could be particularly useful in the identification of septo-cutaneous and particularly myo-cutaneous perforators ( Fig. 12.2B and C ). Moreover, the 3D exoscope could be used to enhance the ability to perform precise dissection of fine structures avoiding damage to the vascular structures of the flap ( Fig. 12.2A ). Finally, it could reduce the donor site morbidity, allowing for the preservation of sensitive and motor nerve structures. The exoscope is extremely manageable and slim, so it can be prepared with sterile covers to be used only for crucial surgical steps. No additional costs and time is required from this perspective, given that the exoscope will be ready for the subsequent microvascular anastomoses.
12.4
Microvascular anastomoses
Microvascular anastomosis remains the most critical step in free tissue transfer, and approaches may vary among different centers. The ideal technique would cause the least trauma possible to the vessel wall, resulting in a reduction in the risk of thrombosis and an increase in short- and long-term patency rates. It is crucial to look for and isolate good quality vessels with a similar diameter. Another important aspect is to avoid any tension at the repair site and any stretches that could result in damage to the anastomosis. Moreover, it is essential to evert vessel walls while suturing to provide direct intima–intima contact.
After the pedicle is ligated at the donor site, a partial flap inset is performed with or without the aid if the exoscope. Then, the holding system should be placed to obtain a focal distance of about 30 cm from the surgical field where the anastomoses should be performed. In our experience, this is the optimal distance to obtain an adequate working space to avoid any interferences during subtle maneuvering of the hands. The patient is placed in the Boyce position, with the neck rotated contralaterally and the sternocleidomastoid muscle retracted with self-retractors to improve the surgical field. The 3D exoscope is used to prepare both recipient and donor vessels. In particular, trimming of the adventitia is performed in the area of the proposed anastomosis and in the area where the clamp is to be applied. Background material (e.g., moist sponge) is placed beneath the vessel set-up, and vessel clamps are applied. Suturing technique is not different from the traditional one, and no limitations are determined by the use of the exoscope. Both end-to-end ( Fig. 12.3 ) and end-to-side ( Fig. 12.4 ) anastomoses could be obviously performed. As a consequence, each surgeon could perform the anastomoses with its traditional technique.
