Since the acquisition of the da Vinci SP by our center, we have described in previous studies our experience and results with this platform in patients undergoing robotic radical prostatectomy.17,19,21 Although minimally invasive techniques such as robotic surgery decrease perioperative impacts, surgical outcomes depend on several different factors, such as preoperative patient characteristics, age, SHIM score, cancer stage, and comorbidities.10,13,22,23 In addition, surgical technique and nerve-sparing degree also play an important role along with postoperative management and patient follow-up protocols.8,24 Due to the multifactorial influence on surgical outcomes, to assess the differences and possible benefits of the da Vinci SP and Xi robotic platforms, our study compared two groups with similar preoperative demographics (selected with a Propensity Score matching) undergoing robotic radical prostatectomy.
Regarding intraoperative performance, the Xi robot provided faster operative and console time than the SP, mainly due to the greater traction and dissection capacity provided by the arms and instruments. As previously described, the SP has bi-articulated and flexible arms of 6 mm, while the Xi has an independent rigid arm of 8 mm with articulation like the human wrist. Therefore, SP presents greater limitations when used in obese patients, and in those with previous abdominal surgeries or enlarged prostates. When designing our selection criteria, based on our experience in robotic prostatectomy, we selected factors that typically increase surgical challenges or potentially risk surgical outcomes.15–17 Patients with previous abdominal surgeries are more likely to have adhesions, and the SP trocar is a limitation for performing adhesion lysis unless you add extra trocars for a laparoscopic approach, which may contradict the SP concept of performing surgery with only one or two incisions.
In a retrospective study, Vigneswaran et al. compared 50 consecutive patients undergoing prostatectomy with the SP to 113 operated on with the Xi.25 The authors reported a shorter hospital stay and less postoperative pain in favor of the SP, although both groups were similar regarding the use of morphine. On the other hand, despite the larger cohort, comparing patients with similar preoperative characteristics, our study failed to demonstrate clinically significant differences regarding postoperative pain reported by patients 6, 12, and 18 hours after surgery. As we use a TAP (Transversus Abdominis Plane)26 block in all patients, the pain scores of our study tend to be close to zero in both robots. Our results showed a difference of a half point in the pain scale 6 hours after surgery favoring the SP, whereas there was no statistical difference in the other evaluated periods (12 and 18 hours). Therefore, we consider that there is no clinically significant difference in postoperative pain between the groups.
With the current technological expansion of robotic surgery and new consoles being launched on the market, it is natural to compare surgical performances and results between different platforms. However, we believe that the current generation SP is not a robot to replace the multiport Xi but to complement its use in patients who are not candidates for the multiport approach, such as patients with ileostomy, colostomy, penile prosthesis with reservoir, kidney transplants, and other intra-abdominal obstacles.27 Recently, some authors have described the transvesical access that can further expand the use of SP in these patients with a hostile abdomen..20,21,28 However, the functional and oncological results of this technique are still under discussion.
Our study is not devoid of limitations, mainly due to the retrospective design and all inherent risks of bias. Furthermore, as described in several studies, the experience of a high-volume center is generally not reproducible in smaller centers with less experienced surgeons.29,30 However, we believe that with adequate selection criteria, the surgical results of patients operated with the SP tend to be constant even during the learning curve.19 Finally, to date, this is the largest series comparing perioperative outcomes in patients with similar preoperative characteristics undergoing radical prostatectomy with the SP and Xi robots. However, prospective and randomized studies are still needed to compare the real differences and advantages between both consoles.