Standardization and ten essential steps in the lateral robotic extended totally extraperitoneal (eTEP) repair of ventral hernias

Objectives: described by Dr. Jorge Daes, principles of the enhanced view totally extraperitoneal (eTEP) has been widely used in the armamentarium of ventral hernia repair recently. Robotic assisted eTEP technique feasibility has been proved, however, a complete understanding of retromuscular abdominal wall planes and its landmarks still uncertain in a majority of general surgeons. The aim of this report is to propose a technical standardization and its anatomic concepts in the robotic-assisted eTEP ventral hernia repair. Methods: our group describes 10 key steps in a structured step-by-step approach for a safe and reproducible repair based on well defined anatomic landmarks, identification of zones of dissection and correct restoration of the linea alba. Results: the standardization has been developed 2 years ago and applied to all patients. A robotic-assisted surgery with 3 robotic arms is performed in a lateral docking setup. Feasibility is established and reproducibility is high among general surgeons. Conclusion: we present a standardized side docking robotic assisted eTEP approach for ventral hernia repairs with 10 key steps. We believe understanding the landmarks and a step-by-step guidance based on the concepts of retromuscular abdominal wall anatomy foment a safe learning of minimally invasive restoration of the abdominal wall integrity regarding non-expert surgeons.


The biomechanics of the abdominal wall
The abdomen behaves like a hydraulic system with normal intra-abdominal pressure of about 5 to 7 mmHg 9 . Restoration under physiological pressure of the linea alba should be the main objective of the ventral hernia repair, different than what was previously thought, i.e., only a tension-free correction.

Anatomical landmarks
Anatomically, the anterolateral abdominal wall is mainly formed by four symmetrical paired muscles. In addition to these four muscles (external oblique, internal oblique, transversus abdominis and rectus abdominis), the fascia transversalis and the parietal peritoneum are also important landmarks of the abdominal anatomy 10 .
The abdominal rectus muscle is involved in an aponeurotic sheath, consisting of the aponeurosis of the lateral abdominal muscles, completely involving its fibers anteriorly, and partially in its posterior aspect, above the arcuate line. At both lateral edges of the rectus muscle, there is a curved tendon intersection formed by the aponeurosis of the internal oblique, reinforced anteriorly by the external oblique and posteriorly by the transversus abdominis above the arcuate line, called linea semilunaris.
The arcuate line is the lower limit of the posterior layer of the rectus sheath, marking the transition from the retromuscular plane, which inferiorly consists only of the fascia transversalis and the parietal peritoneum.

Ten essential steps of standardized technique
Step 1: Positioning the patient All patients should be placed in the supine position, with arms closed along the trunk. For the greater distance between the costal margin and the antero-superior iliac crest, it is essential to flex the table, avoiding a possible external collision of the robotic arms.
( Figure 1A). We encourage the insertion of a delayed bladder catheter to guarantee an empty bladder during the operation. The 30° endoscope should initially be pointing upwards towards the abdominal wall.
Step 3: Ipsilateral retromuscular dissection Once the instruments and the optics are properly positioned, the first goal in the third step is to get an ample ipsilateral retromuscular space, ensuring a broad and ideal workspace. The medial border of the rectum must be exposed along the cranio-caudal length.
The epigastric vessels and muscle fibers are exposed above, and the posterior sheath and the fascia transversalis below, respectively cranial and caudal to the arcuate line ( Figure 2A and 2B).
Step 4: Crossover maneuver and reduction of hernia content The crossover maneuver, described by Beliansky et al. 6      Step 9: Restoration of the anterior abdominal wall and of the linea alba Once the posterior fascial layer is repaired, the next surgical step is to restore the midline. The 30° optics must then face upwards, providing the ideal visualization of the defect size and of the ipsi and contralateral edges.
Not infrequently, there is rectus abdominis muscle diastasis and the edges should also be approximated, concurrently with the defect closure ( Figure 5A and 5B). If using the da Vinci Xi robotic platform, the image inversion maneuver can be extremely valuable, helping even more in the ergonomics and suturing of the anterior abdominal wall. This view is created by the maneuvers sequence both in the robotic console and in the instruments. In the robotic car next to the patient, one must reverse the instruments so they will be in a configuration opposite to the original one, followed by the reversal of the optics by 180°. Then, in the robotic console where the surgeon is seated, the instruments must be reassigned to the opposite hands, the command is confirmed, and the 30° optics, moved in the opposite direction. This way, the suture that would be anteriorly held in the superior aspect of the surgical field is converted to a suture in the inferior field, of greater familiarity in minimally invasive procedures ( Figure 5C and 5D).
If not yet set, in this step it is also recommended the reduction of the CO2 pressure and the use of multiple barbed sutures along the defect, progressively promoting tension at the edges, thus avoiding tissue rupture when there are larger defects.

RESULTS
The standardized technique has been used by a group of surgeons whose series is one of the largest Guidelines for uniform teaching and surgical learning can contribute to achieving high quality standards 19 .