Surgical procedure and analysis

Surgical procedures were performed and evaluated according to a standardized protocol (see Fig. 2) and according to the legal national legislation without the necessity to obtain an approval by the institutional ethics committee of the Technical University of Munich, Klinikum rechts der Isar. Six participants performed 10 arterial and 10 venous anastomoses with the operating microscope type OPMI® Pentero® (served as the reference; INFRARED 800; Carl Zeiss Meditec AG; Oberkochen, Germany) and the exoscope-guided 3D system (Karl Storz GmbH; Tuttlingen, Germany) in the chicken thigh model using a 10–0 Ethilon suture (10–0 Ethilon®, Ethicon; Norderstedt, Germany)¹⁴ All participants used the same microsurgical instruments and equipment required for anastomosis (S&T AG; Neuhausen, Switzerland). Refrigerated chicken thighs (EDEKA Bio WWF Chicken Thigh 1 kg) were obtained in a nearby supermarket and disposed in an appropriate container after successfully completing the surgical procedures and evaluations.

Setup of the study.

The time in minutes per arterial and venous anastomoses and the number of sutures performed were registered, and the time per suture in minutes was calculated. Each of the anastomoses was then randomized and evaluated independently by a blinded microsurgeon based on its patency and whether the back wall had been sewn on and the adventitia had been sewn in (see Fig. 3). The patency of the anastomoses was directly related to whether the posterior wall was sewed on and therefore only recognized when this was not the case.

Anastomoses of the artery (A) and vein (V) as performed by the participants in the chicken thigh model. The artery has been opened to evaluate the quality of the sutures and its patency.