Study population
An experimental study was conducted among surgical residents assigned to the French Military Health Service Academy, Ecole du Val de Grâce, Paris. Included were residents from all specialties who had not yet training in microsurgery. Excluded were residents who had already been enrolled in a university degree in microsurgery.
Experimental protocol
The aim was to simulate the performance of various types of microvascular anastomoses over four training sessions. The simulation model was based on Japanese noodles of the konnyakushirataki type as described by Prunières et al. [8]. Sutures were performed using standard microsurgical instruments (needle driver, dissecting forceps, double and single clamp) using surgical magnifiers with 3.5x magnification (YEARSUN, China) and 10.0 nylon thread.
Each session followed the same protocol and was supervised by a qualified microsurgery instructor:
1. The participant adjusted his magnifiers after explanation and demonstration by the instructor (Fig. 1A);
2. Each noodle was pierced with an intravenous catheter to provide visible and uniform light [8];
3. The anastomosis was described by the instructor with the help of an explanatory diagram, then the suture was started after internal understanding of the objectives of the session;
4. The amount of time taken to perform the anastomosis was measured and the handling of the instruments evaluated by the monitor.
At the end of each session, the instructor checked the permeability and quality of the anastomosis while the participant completed a self-assessment questionnaire.
Table I details the content of each of the sessions which consisted of various anastomosis of increasing difficulty: end-to-end anastomosis, end-to-side anastomosis and bypass with double end-to-end anastomosis (Fig. 1B) [9, 10].
Evaluation parameters
The anastomosis patency and the existence of leaks were assessed by injecting physiological saline through a catheter inserted proximally to the model [8].
The quality of the anastomosis was assessed from the inside after a longitudinal opening of the noodle (Fig. 1C). The assessment was based on an adaptation of the rating scale described by Chan et al. [11] according to three criteria scored from 1 to 5: instrument handling, repair of stitches and quality of stitches. The criteria for assessing the quality of the stitches were symmetry of the grip of the two edges, the tightness of the knots, the occurrence of a wall tear or a transfixing grip (Table 2).
The duration of the anastomosis procedure was also evaluated. It corresponded to the time elapsed between the positioning of the noodle on the double clamp and the section of thread during the last stitch. The amount of time was split in two during session 4 which included two anastomoses.
The subjective end-of-session self-assessment was performed using the SAMS (Structured Assesment of Microsurgery Skill) questionnaire, which has a high inter-rater reliability [11]. Fourteen criteria scored from 1 to 5 were assessed, with a maximum score of 70.
The primary endpoint was the comparison of scores obtained between the first and last session. The secondary endpoint included: 1) an independent assessment of each criterion in our rating scale; 2) a comparison of the participant’s self-assigned scores; 3) a comparison of the length of completion time between anastomoses during the resident’s advancement.
Statistical analysis
Data were collected using Excel software (Microsoft Corp., Redmond, WA, USA) to calculate means and standard deviations. Statistical analysis was performed using R software [12]. A p value <0.05 was considered statistically significant.