How to Establish the Bipolar Forceps Dissection Method in Robotic Inguinal Hernia Repair

Abstract The number of robotic inguinal hernia repair (RIHR) surgeries performed by younger surgeons and surgical residents has been growing worldwide. As a result, there has been growing interest in the pace at which surgeons develop their competencies. In Japan, the number of robotic surgeries with the double bipolar technique for gastric cancer is increasing. We devised an RIHR technique for a right‐hand‐dominant surgeon. This article describes the procedure and step‐by‐step instructions for this technique. We also assessed the learning curve of a surgeon experienced in the laparoscopic transabdominal preperitoneal (TAPP) approach and robotic gastrectomy. This was a retrospective review of 31 inguinal hernia patients (40 lesions) between December 2018 and April 2021 operated by a single surgeon. The cumulative summation technique (CUSUM) was used to construct a learning curve for robotic proficiency by analyzing the times for peritoneal flap creation, mesh placement, and peritoneal closure. The postoperative course, namely, the length of hospital stay, 30‐d complications, and 30‐d readmission rates, was evaluated. The CUSUM graph for the total time for each phase indicated an initial decrease at lesion 12 and another decrease at lesion 36, generating three distinct performance phases: learning (n = 12 procedures), competence (n = 24), and mastery (n = 4). Between the early and late periods, no significant differences in patient characteristics or surgical outcomes were found. The learning curve for this technique was divided into three performance phases, and the technique was safely achievable in 36 procedures by a surgeon with previous experience in laparoscopic TAPP.

curve (LC) of robotic inguinal hernia repair (RIHR), and there is no consensus on the criteria for operating surgeons. In comparison, in Japan robotic surgery is increasingly being performed for gastric cancer and rectal cancer. 3,4 Many surgeons perform robotic gastrectomy (RG) using the double bipolar technique, and a decrease in postoperative pancreatic fistula formation in radical lymph node dissection has been reported. 5,6 Uyama et al reported that Maryland forceps, which are controlled by the surgeon's dominant hand, are appropriate for precise dissection because of their articulation, tapered tip, ability to hold the tissues under dissection, and efficient hemostasis. 7 Thus, we established our surgical technique by introducing RIHR with the transabdominal preperitoneal approach (R-TAPP) using the bipolar method. In this article, we describe the surgical technique of this method, focusing on the LC of a single surgeon. We used the cumulative summation technique (CUSUM), which is a popular and reliable method for evaluating the LC of a surgical procedure.

| PATIENTS AND ME THODS
Between December 2018 and April 2021, consecutive patients who underwent R-TAPP using the bipolar forceps dissection technique at our institution were investigated. All operations were performed under a protocol designed at our hospital by a single qualified surgeon (Takuya Saito) who completed the LC for laparoscopic inguinal hernia repair with the transabdominal preperitoneal approach (L-TAPP) prior to performing R-TAPP. 8,9 In addition, the operating surgeon performed more than 50 RGs within the study period. The patients' demographics, clinical characteristics, intraoperative data (console time, total operative time, and blood loss), and 30-day postoperative outcomes (overall complications, length of stay, and readmission) were reviewed. Postoperative complications comprised surgical site infection, urinary retention, small bowel obstruction, ileus, continuous severe pain, and abdominal abscess.
All patients provided written informed consent before undergoing surgery. In December 2018, we introduced R-TAPP as a treatment option after obtaining approval from the Ethical Committee of Aichi Medical University (AMU) Hospital. This study was approved by the Institutional Review Board of our institution (No. 2019-086) and was performed in accordance with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

| Access, port position, and instruments
All procedures were performed using the da Vinci Xi robotic plat-

| Mesh placement and fixation
We used a polypropylene mesh (15 x 10 cm) that was sutured and fixed to the left and right sides of the IEV, CL, and the rectus muscle ( Figure 4A). The mesh was rolled up and inserted through the working trocar. In the process of establishing our surgical technique, the polypropylene mesh was fixed with tacks by the bedside surgeon or a self-fixating mesh (Parietex ProGrip; Medtronic, Dublin, Ireland; Figure 4B) was used (the procedure is demonstrated in Video S3). The self-fixating mesh is difficult to insert from the 8 mm trocar. Therefore, when we envision the use of this mesh, a 12 mmumbilical trocar is placed from the beginning of the operation.

| Peritoneal flap closure
The intraperitoneal pressure was decreased to 8 mmHg to reduce tension during suturing. We started suturing from medial to lateral

| Statistical analysis
Continuous variables were expressed as median (range) and were compared between the early and late periods using the chi square test, the Mann-Whitney U test, or Fisher's exact probability test, as appropriate. All P values were two-sided, and P < .05 indicated a significant difference. For this study, CUSUM graphs were generated from the three phases of the console time and the total time. The LC stages were determined from the times on the CUSUM graphs.
All statistical calculations were performed with JMP statistical software, v. 13 (SAS Institute, Japan).

| Patients' characteristics and perioperative outcomes
Thirty-one consecutive patients (40 lesions) were analyzed. Table S1 shows the patients' characteristics, and Table S2 shows the patients' perioperative variables. There were no significant differences be-

| Evaluating the learning curve using CUSUM
The median time required for the peritoneal incision phase was 30 min (range, 18-54 min), that for the mesh placement phase (including fixation) was 13 min (range, 6-30 min), that for the peritoneal suturing phase was 10 min (range, 3-28 min), and that for total time for all phases was 54 min (range, 33-86 min; Table S2). The CUSUM graph for the total time of phase-identified changes in slope at lesions 12 and 36 divided the LC into three distinct stages ( Figure 5).
In each phase, the CUSUM graph also identified changes in slope at lesions 10 and 35, which divided the LC into three distinct stages ( Figure S1-S3).

| DISCUSS ION
The advantages of a bipolar dissection technique in R-TAPP are the ability to maintain adequate operative field control with both hands, delicate dissection, and efficient hemostasis. As a result, we consider that peritoneal flap creation and parietalization of spermatic cord components may be performed more safely. R-TAPP is usually performed with the left hand using fenestrated bipolar forceps for grasping and hemostasis, and with the right hand using a monopolar instrument (scissors/hook) for dissection (Intuitive Surgical). This method is difficult to perform because the surgical field is controlled By evaluating the surgeon's LC after completing the LC for L-TAPP, three different stages were observed. The phases of the LC and the total time changed at lesions 10 and 35. The three stages indicated the surgeon's comfort operating the robot, competency, and mastery, respectively, as the surgeon developed experience.
The three stages generated corresponded to the learning, competency, and mastery stages delineated in previous studies of surgical LC. 11,12 Our evaluation of the LC of a simple surgical technique excluded the effects of differences, such as surgical team performance or docking the da Vinci robotic system, other than operative or con- With other approaches, any hole in, or failure of, the peritoneal flap is located directly over the mesh, exposing the mesh to the bowel.
This approach was possible with the enhanced endo-wrist dexterity of the DVSS, and postoperative pain prevention was expected owing to the tackless mesh fixation. 19 The heterogeneity of the cases potentially confounded our results, as each case involved a unique set of steps and mesh choice, and required certain skill sets, such as mesh fixation. However, considering the fact that hernia defects and adhesions differ, modifying the procedure while standardizing the technique is acceptable.
There was no significant difference in outcomes between the early and late periods in this study. In addition, although two postoperative complications were observed in the late period, these were Clavien-Dindo classification grade 1. 20 R-TAPP using bipolar forceps by a surgeon who completed the LC for L-TAPP had three performance stages and was feasible by The limitations of this study are that it involved a retrospective cohort, a single surgeon's experience, and a small sample size.
Further validation studies involving large sample sizes for various surgeons are needed.