LAUSR

Basic supermicrosurgical suturing skills are a minimal requirement for supermicrosurgeons. Many nonliving models for supermicrosurgical training have been reported, such as chicken models and silicon tube card models (Chen et al., 2014; Matsumura et al., 2009; Rodriguez et al., 2016; Yamamoto et al., 2013; Yamamoto et al., 2014). Most studies reported training models for end-to-end and end-to-side anastomosis, but there are few reports of side-to-side supermicrosurgical anastomosis model. However, among four basic anastomosis, side-to-side anastomosis is the most demanding technique, but on the other hand, side-to-side anastomosis has an important role in providing multiple bypasses to maximize drainage. In the clinical setting, side-to-side anastomosis was reported in sequential and ladder-shaped anastomosis configuration, as this configuration showed maximize bypass by giving bidirectional retrograde and normograde lymph flow when facing more than one lymphatic vessel in one venule, which further contributes more efficacious bypass (Yamamoto et al., 2013; Yamamoto et al., 2014). Sequential anastomosis in human lymphatic vessels was used when the number of lymphatic vessels were more than the number of veins (Yamamoto et al., 2014). While ladder-shaped anastomosis in patient lymphatic vessels could be performed when there are three lymphatic vessels and one vein in a surgical field, which diverts bidirectional lymph flows of the three lymphatic vessels into one vein with multiple side-to-side anastomoses (Yamamoto et al., 2013). Major drawbacks of side-to-side anastomosis include technical difficulty and risk of total obstruction in multi-bypass cases (Yamamoto et al., 2013; Yamamoto et al., 2014). We have developed a new supermicrosurgical side-to-side anastomosis model using ulnar vessels of the chicken wings, with Vshaped traction method (Figure 1). The anatomy of the ulnar veins was consistent, with a diameter from 0.30 to 0.70 mm (average, 0.48 mm) was appropriate for supermicrosurgical training. A background sheet with V-shaped slits was useful to simulate a real side-toside supermicrosurgical anastomosis condition as seen in various clinical side-to-side lymphaticovenous anastomosis settings. This technique was yielded since both veins in chicken wings located sideby-side, attaching to each other, by applying this technique we make a space to separate those veins. The background sheet is usually sized 2 cm × 1 cm, made of plastic, and has a distinct color. A snip as a small oblique shape, imitating unfinished V alphabet, were made on one side of the sheet, with a distance between the slits ranging from 0.3 to 0.5 cm. Furthermore, each vein was inserted in each specific slit. The slits distance, which will affect the veins distance later, can be preferably managed by the supermicrosurgeons to ease their practice. After the veins were positioned in specified slit, anastomosis could be conducted. Firstly, venotomies was performed on the lateral walls of the two veins with microscissors, and side-to-side anastomosis was performed with 12–0 microsuture in an interrupted suture fashion under 25–32 times magnification. Anastomosis consisted of six to seven suture knots. Time for anastomosis ranged from 15 to 60 min (average, 24.6 min). Anastomosis time could be shortened within 20 min from eighth practice. Our results showed significant decrease in time for performing side-to-side supermicrosurgical anastomosis, conducted by a beginner supermicrosurgeon. This represents usefulness of the training model for microsurgeons who want to start supermicrosurgery. Although it is difficult to check quality of anastomosis created in training due to lack of hemodynamic circulation, our new training model is useful to simulate clinical conditions of side-to-side lymphaticovenous anastomosis, it would play an important role to improve quality of side-to-side supermicrosurgical anastomosis, as the model allows readily available convenient training suitable for daily practice.