Conception and prospective multicentric validation of a Robotic Surgery Training Curriculum (RoSTraC) for surgical residents: from simulation via laboratory training to integration into the operation room

Conception of RoSTraC included several aspects that are in our opinion relevant for structured and effective RAS training for surgical residents.

Second, the curriculum should enable surgical residents to become part of the in-clinic robotic surgical team. To ensure this in a safe way, the curriculum provides multimodal RAS learning contents including theoretical basics, RAS basic skills, complex RAS skills, and operation room training. To clearly structure the multimodal RAS training, RoSTraC was divided into three steps. The first step consists of theory and VR training. The second step includes an in vitro laboratory (lab) training on training boxes and synthetic biological organ models for the training of basic and complex RAS skills. In the last step, training takes place in the operating room including observation and assisting in robotic procedures and performing surgical steps on the console, all of which can be completed over a period of about 1 year (Fig. 1).

The first step of RoSTraC includes the theoretical basics about the following RAS topics: available robotic systems, the evidence of RAS and the economics of RAS. The theoretical basics of the RAS topics are provided on the one hand by selected literature and on the other hand by video lectures on the above RAS topics, which are created and presented by the trainees at the regular video meetings. In addition, these video lectures are made available to further trainees via upload into the cloud. In addition, step 1 of RoSTraC includes RAS video training that explains step-by-step RAS procedures in visceral surgery. Parallel to the acquisition of the theoretical basics of RAS, a technical introduction to the in-clinic robotic system is provided by the manufacturer of the robotic system. As transferability of the curriculum to any existing device was within the scope of the curriculum this part is mainly dependent on close cooperation with the manufacturer of the robotic system. Therefore, the trainees complete the VR training provided by the manufacturer of the robot system. Successful completion of the first step of RoSTraC requires a successful completion of VR training. Step 1 takes about 3 months to complete (Fig. 1).

The second step of RoSTraC consists of a laboratory (lab) training using different training modalities such as training boxes and synthetic biological organ models at different levels of complexity and difficulty. All these exercises are carried out with the on-site robotic system in the operating room using the console, patient cart, video cart, a box trainer and training instruments.

At first, RAS basic skills are learned which include bimanual coordination, handling the complete loss of haptics, usage of instruments with increased degrees of motion freedom, coordination of camera and general handling of the robotic system. For the acquisition of these RAS basic skills, we used the “Lübeck Toolbox” (LTB) exercises as previously described [6] (Fig. 2). Video tutorials have been created for each of the six LTB exercises, explaining how to perform the exercise correctly. For LTB exercises A, B, C and F, a robotic grasping instrument and a robotic needle holder were used. A robotic grasping instrument and a robotic scissors were used for exercises D and E. The exercises had to be repeated until the objectives of the exercises (expert level) were reached in at least 2 repetitions.

After the acquisition of RAS basic skills, four exercises with increasing levels of complexity are performed on synthetic biological organ models. The synthetic biological organ models consist of a synthetic human torso and synthetic organs of the upper abdomen (HumanX GmbH, Wildau, Germany) (Fig. 3). In particular, the exercises on synthetic organ models mimic realistic robotic operations, namely suturing an enterotomy in the small intestine, a cholecystectomy, a closure of a perforated duodenal ulcer and a latero-lateral gastroenterostomy. These synthetic organ models can be used without hygienic limitations in every hospital. In the following, the individual exercises on the synthetic organ model are explained in detail.

In the first exercise (No. 1), a 5 cm enterotomy in the small intestine must be closed with a continuous suture in both the horizontal and vertical directions (PDS II 4–0 (Ethicon Inc.) shortened to a length of 8 cm) with anchoring knots (Fig. 3A). This procedure is successfully completed when the target time of 6:15 min is reached (expert level, see benchmark study) and the exercise has been repeated at least 20 times. For this procedure, one robotic grasping instrument and one robotic needle holder are used.

The subsequent exercises (exercises No. 2–4) train not only RAS skills of increasing complexity including entire RAS procedures, but also the efficient use of the additional 4th robotic arm for exposure the surgical field. Two robotic grasping instruments, a robotic needle holder and a monopolar scissors are used for these exercises.

In exercise No. 2 (Fig. 3B) on the synthetical biological organ model, a perforated duodenal ulcer is closed with three single sutures each using a PDS II 4-0 (Ethicon Inc.) suture shortened to 8 cm while lifting the liver that covers the duodenum using the fourth robotic arm.

Next, a cholecystectomy is practiced (exercise No 3; Fig. 3C). Using the additional fourth robotic arm, the gallbladder is exposed. Analogous to the principles of MIS cholecystectomy, a dissection of Calot’s triangle is performed. The cystic duct is cut between two ligations (Vicryl 4-0, shortened to 8 cm (Ethicon Inc.)). Finally, the gallbladder is dissected from the liver with the monopolar scissors.

Finally, a lateral-lateral gastroenterostomy is performed as the most complex exercise (exercise No. 4; Fig. 3D). The stomach is first exposed by lifting the liver with the additional fourth robotic arm. Then, a loop of small intestine is sutured to the large gastric curvature with a self-anchoring suture (V-Loc™, Covidien/Medtronic) over a distance of about 4–6 cm. This is followed by a gastrostomy and enterotomy over a distance of 4 cm using the monopolar scissors. Lateral-lateral gastroenterostomy is then performed with a double-armed PDS II 4-0 suture (Ethicon Inc.). First, the posterior wall is sutured continuously, followed by the anterior wall. Both ends of the suture are finally knotted. The closure of a perforated duodenal ulcer, the cholecystectomy, and the gastroenterostomy are repeated 5 times each. For standardization and comparison, all exercises and surgical procedures must be performed exactly as instructed in the video tutorials. To test the acquired RAS skills and to provide feedback to the trainee on her/his RAS skills, the last robotic gastroenterostomy will be recorded, uploaded to the cloud and evaluated by an expert in robotic surgery using the validated multidimensional Global Evaluative Assessment of Robotic Skills (GEARS) score [12]. Step 2 takes about 3–6 months to complete (Fig. 1).

The choice of content for the exercises in step 2 was based on the following considerations: First, we integrate toolbox exercises from the LTB in step 2 to teach the basic skills of MIS, such as how to deal with altered or lacking haptics. The contents of the LTB have already been validated in previous studies [6]. Next, we integrated exercises on synthetic organ models in step 2 to train a RAS procedure ex vivo in a safe environment before step 3 of the RoSTraC, where RAS procedures are performed in the operating room on the patient. The RAS procedures on the organ models teach the skills required for step 3, such as the dissection of tissue in the correct layers, the effective use of the additional robotic arm in exposing the surgical situs and the suturing of anastomoses.

In the final step, training takes place in the operating room during RAS procedures on patients. First, this step includes at least 30 observations and at least 40 assists in RAS procedures. This is followed by taking-over of individual minor steps of a RAS procedure (such as for example control of camera while changing focus, exposure of situs with four arms, minor cutting or suturing steps, mobilization of for example the ascending/descending colon or similar) at the console under the supervision of an experienced robotic surgeon. The type of procedures is based on the specialty of the trainee’s surgical clinic. In the further course of the training, the trainee has to perform a minimum of 5 major sub steps of complex operations, or simple small operations. Examples are mobilization of the colon (including the right or left colonic flexure), hiatoplasty, gastric wedge resection, sigmoid resection or similar. This part of training aims at a more extensive exposure to RAS under supervision. This step finally leads to the trainees becoming an integral part of the robotics team in their own clinic. This step takes about 6 months to complete (Fig. 1). It should be noted that in RoSTraC the observations and assists in RAS procedures do not necessarily have to take place after the successful completion of step 2, but can take place parallel to step 2. However, taking-over individual steps of an RAS procedure in the operation room should only be performed after successfully passing step 2.

To determine an expert level for the LTB exercises and the robotic procedure of suturing of a segment of small intestine, four experienced robotic surgeons from two surgical centers were recruited. These surgeons, each, had performed more than 50 RAS procedures. For standardization, all experts received access to the RoSTraC cloud and watched the video tutorials explaining the exercises. Then, all exercises were repeated three times subsequently. Each repetition was performed respecting the pre-defined precision. For the definition of the expert levels or the respective exercises, the mean values of the execution times of all experts (in seconds) were calculated.

A prospective multicenter study was conducted to validate RoSTraC by determining the learning curves and demonstrating the transferability of the acquired skills to a RAS procedure. The prospective trial was approved by the ethics committee of the University of Lübeck (#2022-568). Study participants were surgical residents in the last years of their surgical residency and surgeons who have just completed their residency in general or visceral surgery. Seven study participants from five different surgical clinics in Germany were recruited for the validation study. All study participants signed informed consent. The study was conducted on-site at the surgical clinic where the study participants were undergoing their surgical residency for general and/or visceral surgery. All participating surgical clinics had a DaVinci Surgical Si or a DaVinci Surgical Xi system (Intuitive Surgical Inc.) and provided equipment to perform the RoSTraC. LTB training boxes and synthetic biological organ models for step 2 of the curriculum were provided by the study center (University Medical Center Schleswig–Holstein Campus Lübeck, Department of Surgery). The study participants completed RoSTraC as described above. The VR training in step 1 of RoSTraC was performed using the DaVinci Skills Simulator (Intuitive Surgical Inc.) as defined by Intuitive Surgical Inc. including a total training time of 40 h. As baseline of RAS performance, all study participants performed a robotic gastroenterostomy on the synthetic biological organ model as described above after completing the first step of RoSTraC (pre-test/GE I). Following the pre-test, the study participants completed the second step of RoSTraC as described above. For the evaluation of the learning curves, the study participants documented the repetition times of all exercises in step 2 and uploaded them to the RoSTraC cloud. GE I (pre-test) and the last robotic gastroenterostomy at the completion of step 2 of RoSTraC (GE II) were digitally recorded and the videos were uploaded into the RoSTraC cloud for assessment by the study center. Due to technical limitations on unsuccessful video recording, video evaluation was only possible for 5 out of 7 participants. Video assessment of GE I and GE II was performed by three RAS experts using the multidimensional GEARS score [12]. The determination of the GEARS scores by the three RAS experts was performed blindly and independent from each other. Changes from GE I to GE II were analyzed.

In step 3 of RoSTraC, the study participants documented the number of assists of RAS procedures on the patient cart and the number and type of performed steps of RAS procedures on the console and uploaded data to the RoSTraC cloud.

Data processing and statistical analysis were performed using Excel (Microsoft Corporation). Ordinal and nominal variables were expressed as absolute numbers and percentage. Bar charts were used to visualize results. Learning curves were calculated with Excel (Microsoft Corporation). For comparison of GE I and GE II according to the GEARS Score, the paired sample t-test was used. The changes from GE I to GE II were indicated by mean values and standard deviations. For all statistical analyses, a p value of p ≤ 0.050 was considered significant.

The results for determination of the expert level are shown in Table 1 (benchmark study).

Seven study participants from five RAS centers in Germany participated in the validation study. The mean age of study participants was 34 years (31–41 years), with 64.3% male and 35.7% female. 69.2% of study participants have completed their surgery residency training in visceral surgery within the last year in average (range since completion of training: 0–70 months), and 30.8% were surgical residents in their final years. All study participants were right-handed. 30.7% of study participants play a musical instrument and 15.4% play video games regularly (once a week).

All study participants met the objectives of the VR training on the DaVinci Skills Simulator^®. The study participants needed in median 3 repetitions (range 1–9) to achieve the targets of the DaVinci Skills Simulator^® exercises (DaVinci Intuitive Surgical Inc). In average, after 8 h of VR training, all targets of the DaVinci Skills Simulator^® were successfully achieved.

For the LTB exercises, study participants required a median of 3 (range 2–5) repetitions for exercise A “pack your luggage”, 4 (range 2–6) repetitions for exercise B “weaving”, 3 (range 2–7) repetitions for exercise No. C “nylon twist” and 4 (range 3–5) repetitions for exercise D “triangle cut” to achieve the defined target times (expert level). More repetitions were required for exercise E “hammer cut” with a median of 6 repetitions (range 4–10). For the last LTB exercise F “suturing”, a median of 9 (range 7–12) repetition were required to achieve the defined target times (expert level).

The learning curves of the RAS procedures on the synthetic biological organ models are shown in Fig. 4. For the RAS procedure “suturing of a segment of small intestine”, the median number of repetitions to reach the objectives (expert level) was 11 (range 3–15). At the beginning of the learning curve, there is a steady improvement in execution times until a plateau phase was reached after approximately 11 repetitions. The value of the benchmark study (expert level: 375 s) was located at the beginning of the plateau phase of the learning curves of study participants. The learning curves of the other 3 robotic procedures on the synthetic biological organ models, which were repeated 5 times each, showed a steady improvement in the execution times. However, a plateau phase was not reached within the 5 repetitions in the learning curve (Fig. 4).

Blinded evaluation of the robotic gastroenterostomy before (pre-test/GE I) and after (GE II) step 2 of RoSTraC revealed a mean GEARS score of 17.1 (±5.8) points and 23.1 (±4.9) points, respectively (Fig. 5). This improvement in GEARS score was statistically significant with p < 0.001. In addition, surgical participants showed a significant improvement in the RAS performance in all domains of the GEARS score including depth perception, bimanual dexterity, efficiency, force sensitivity, robotic control, and autonomy.

With regard to Step 3, “operation room practice” all study participants performed the required number of 30 observations and 40 assists in RAS procedures in the operating room within six months after completion of step 2 of RoSTraC. Furthermore, all study participants performed RAS procedures or major steps of RAS procedures at the console on patients under supervision of an expert in RAS. During the six months following the completion of step 2, study participants performed a median of 12 (range 5–21) RAS procedures on the console including both general surgical and oncological RAS procedures (Table 2).

After successful completion of RoSTraC after one year, study participants evaluated the RoSTraC via an anonymous survey. The results of the questionnaire in terms of relevance to clinical practice, structure, and learning content are shown in Fig. 6. In the evaluation study, 25% of the study participants reported that they conducted the RoSTraC training both in their free time and during working hours. Most of the study participants (75%) reported that they conducted the training curriculum mainly in their free time.

With this current manuscript we describe the conception and validation of the highly standardized and strictly defined proficiency goal-directed RoSTraC curriculum for the acquisition of robotic-assisted surgery skills. RoSTraC provides a highly standardized, comprehensive and efficient training curriculum for RAS for surgical residents. We were able to prove in a prospective multicentric study the feasibility of the cloud-based learning approach for self-contained training of participants at their own institutional robotic system without permanent supervision. More importantly, we could demonstrate that participating surgical residents acquired fundamental and advanced RAS skills, and RoSTraC training led to significantly improved performance of advanced four-hand robotic procedures. Finally, we could confirm that all participants were successfully and safely embedded into the local surgical RAS team as shown by their advanced clinical practice during the last step of the curriculum.