Minimally invasive surgery is entering the era of robotic surgery, beyond the era of laparoscopic surgery. Robotic surgery has overcome the non-ergonomic limitations of laparoscopic surgery and makes MIS possible in several complicated surgeries. Robotic systems have also been developed gradually, and even SP robot systems that can operate with a single hole with minimal invasiveness have been developed. Since the da Vinci SP was launched in 2018, it has only been applied in a few surgical fields. Single-incision surgeries themselves have not received attention because of the risk of surgeries and challenging techniques and have not been popularized to develop more. However, there are several advantages of the SP system in overcoming the potential limitations of single-incision surgeries. We anticipate that our experience with SP robotic cholecystectomy and some previous studies will enable us to pursue MIS with easier techniques and patient safety.
At our center, we have had experience with three types of robotic systems. First, we performed cholecystectomy with the Si and Xi systems and observed that docking was difficult. Additionally, there were still some hand movements that were uncomfortable and collisions of the robotic arms. Subsequently, when we attempted the newly introduced SP cholecystectomy, we found that the SP system was more convenient and ergonomic than the Si or Xi systems and continued to use this system for single-incision robotic cholecystectomy. To confirm the safety, feasibility, and convenience of the new SP system, we analyzed the experiences of all three systems at our center.
The patient population undergoing robotic surgeries at our center was mostly limited to relatively young patients with a lower BMI and ASA less than 3. In Korea, most robotic surgeries are not covered by national insurance and are usually twice as expensive as open or laparoscopic surgeries. Patients without personal insurance usually cannot undergo robotic surgeries. This case selection was similar to that in two previous studies in Korea (3, 4). Moreover, for this reason, patients who have undergone previous upper abdominal surgeries or preoperative ERCP or were suspected of having severe cholecystitis were generally not considered for robotic surgery because adhesion and inflammation might increase the risk of conversion to laparoscopic or open surgery. Nevertheless, there were a few cases in which robotic cholecystectomy was performed in patients with acute cholecystitis and in patients undergoing preoperative ERCP using the SP system. Almost all the procedures were successfully performed, except in one case with acute cholecystitis, which was converted to open surgery. In the study by Kang et al., significantly more cholecystectomies were attempted in patients with acute cholecystitis using the SP than the Xi system (31.9% vs. 1.6%; P < 0.001) (4), which might indicate that acute inflammation or disease severity affected the surgeons’ preference for a specific type of robotic system when performing robotic cholecystectomy. However, when deciding to perform robotic surgery, in addition to the safety of the operation, the medical costs of robotic surgery should not be ignored.
Regarding intraoperative outcomes, iatrogenic bile spillage was observed to occur more frequently in the Si/Xi group, which may indicate that the SP system was easier to control. In addition, the conversion rate in MIS is generally an important indicator of safety and feasibility. The total conversion rate was as low as 0.9%, with no significant difference between the two groups. Previous studies including patients undergoing single-incision cholecystectomy with the Si or Xi system have also reported low conversion rates with 0–3.3% (1, 3, 5).
One of the most distinguishing features between Si/Xi and SP systems was the operation time. Because the Si and Xi systems require a skilled technique for inserting the robotic curved cannula and docking the robot arm, it could take time, and possible dislocation can result in intracorporeal collision. In Fig. 3, the graph of the docking time in the Si/Xi system gradually decreases in consecutive cases, whereas the graph in the SP system shows minimal change. Thus, a learning curve may exist for docking of the Si/Xi system. In this study, there were significant differences in all aspects of operation time, including the docking, console, and actual dissection times. Shorter console and actual dissection times might indicate easier control of the robotic arms during cholecystectomy. Cruz et al. also reported that all three operative times were shorter with the SP system.
The postoperative outcomes, postoperative complications, and postoperative stay were comparable between the two groups. The cosmesis of the umbilical wounds in both groups was similar (data not shown). The SP system requires at least a 2.7 cm transumbilical incision to insert the robotic cannula, whereas the Si/Xi system may require an incision as small as 2.5 cm. These do not affect cosmetic results because the incision is hidden inside the umbilicus. However, the size of the incision may be associated with the rate of incisional hernia formation. In the present study, the total rate of incisional hernias was 1.5%, with no significant difference between the SP and Si/Xi groups. Previously, the rate of umbilical port site hernia after Si/Xi cholecystectomy was reported to be 5.2–8% (5–7) .
Technically, the SP system was simpler and more convenient (Table 4). First, among the numerous advantageous features of the SP system, the third arm controlled by the surgeon for traction of the gallbladder (Fig. 5) and multidirectional EndoWrist function (Fig. 6) are by far the most important factors for easier dissection and easier control of the GB, respectively. Second, in the case of Si/Xi, the previous study by Jung et al. (8) introduced the reverse-port technique to perform dissection around the cystic duct and cystic artery. However, in SP, the arms can be extended using the EndoWrist. Third, in acute cholecystitis, the cystic duct can sometimes become dilated and is thus difficult to ligate using a typical single-size medium-large (green) robotic hemolock. In the SP system, the assistant can insert a larger hemolock (purple) through the gel port beside the insertion site of the SP cannula to clip the cystic duct (Fig. 7). Furthermore, if the cystic duct is too thick or accompanies Mirizzi syndrome, it cannot be ligated even with a large hemolock. However, in the SP system, because it is easier to suture with EndoWrist, primary repair can be performed on the cystic duct stump.
Table 4
Advantages and disadvantages of Si/Xi and SP
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Si/Xi
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SP
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Advantage
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• 3D visualization
• Inversion of the instruments: wider movement, better ergonomics
• Curved 5mm cannulas and semi-rigid instruments restores triangulation
• Remote center tehcnology minimizes collisions, crowding, and trauma
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• 3D visualization
• Easy docking process
• Three working robotic arms → Traction controlled by surgeon
• Multi-joint Endo-Wrist instruments → articulation
• Distal instrument triangulation (at tip)
• 360-degree rotation
• Access narrow space
• 24cm reach
• Flipped camera view
• Broad versatile
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Disadvantage
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• No internal wrist → No triangulation at tip
• Two working robotic arms → Need an assistant for GB retraction
• Difficult docking process
• No suction arms, no energy device
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• No suction arms, no energy device
• Narrow range of motion
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However, this study has some limitations. Its retrospective nature and relatively small sample size may have limited the results. However, all robotic cholecystectomies were performed at a single center, which might help maintain the consistency of the procedure. There were case selections in both groups. Thus, either robotic systems may not be applied to certain patients who have high BMI or underlying disease that would significantly affect the surgical outcomes.
Robotic SP cholecystectomy is safe and feasible in terms of comparable perioperative complications and low conversion rates and is convenient for many newly applied systems. We believe that robotic SP cholecystectomy is more advantageous in terms of the docking process and three robotic arms with multi-joint EndoWrist movement, which gives us reasons not to return to the Xi system.