Robotic miniaturization: Reducing the surgical footprint

After the landmark first laparoscopic nephrectomy in 1991, urologists charted a minimally invasive surgical quest to limit morbidity without sacrificing success during complex operations. Proficient laparoscopy required years to develop with expertise limited to fewer surgeons, especially with such challenging procedures as radical prostatectomy, partial nephrectomy, and pyeloplasty.

Robotic surgery seemingly leveled the playing field, coordinating precision suturing, six degrees of surgical freedom, camera motion, and retraction, all with 3-D vision.

Naturally, there has been a push to reduce the footprint of robotic surgery, including the number of incisions, size of incisions, and the financial and physical impact of the surgical system. However, as with most new technology, the objective merits of robotic miniaturization are still under study.

In this article, we describe current and future surgical platforms and instrumentation designed to meet the goal of minimizing the robotic surgery footprint.

Fewer incisions

With significantly improved patient convalescence and satisfaction transitioning from open to laparoscopic and robotic surgery, it was a reasonable assumption that fewer incisions would improve patient outcomes. Laparoendoscopic single-site surgery (LESS) was a challenge that many accepted, but few conquered. Robotic-LESS (R-LESS) promised to ease the challenge, and the initial series by Kaouk et al demonstrated improved suturing and ease of dissection with the help of the robot (BJU Int 2009; 103:366-9). However, a cross-armed technique was still required.

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Perhaps the greatest concern with early LESS and R-LESS series was whether or not the technique improved surgical outcomes. Early comparative series were small, retrospective, and non-randomized, and demonstrated non-significant clinical benefit in most outcomes, including pain(Eur Urol 2011; 59:26-45). The obvious potential benefit of improved cosmesis was most notable in younger patients undergoing surgery for benign disease (Eur Urol 2011; 60:1097-104). Ultimately, the challenge of the operation along with questionable clinical benefit led to most minimally invasive surgeons abandoning the technique.

It could be argued that the full potential of R-LESS was not realized due to technical challenges; a purpose-built single-site surgical robot could broaden approval. Intuitive Surgical developed the da Vinci SP, a dedicated single-port robot with four double-waisted arms that recreate triangulation after passing through a 25-mm port (figure 1). The first case series using the da Vinci SP demonstrated the feasibility to perform radical prostatectomy, partial nephrectomy, and nephrectomy (Eur Urol 2014; 66:1033-43). This ultimately led to FDA approval in May 2018 for the above-listed procedures, with more recent small case reports of cystectomy(Eur Urol 2019; 75:684-91) and ureteral reconstruction (J Endourol Case Rep March 8, 2019 [Epub ahead of print]).

After accessing the abdomen with a Hasson technique, the 25-mm port can be placed directly into the abdomen or through a product such as GelPOINT (Applied Medical) that allows placement of additional assistant ports through the same incision. Optimal working distance is a minimum of 10 cm from the target anatomy to allow for triangulation of the arms, with a maximal reach of 25 cm. Because da Vinci SP works on a single boom, there is 360-degree access to the abdomen, making multi-quadrant surgery feasible through a single incision. Such surgical freedom was not possible with prior R-LESS technology.

In addition, the single port allows the potential to access more confined surgical approaches: retroperitoneal, extraperitoneal, and areas with significant surrounding adhesions. More natural handling, especially given the familiarity with other da Vinci robots, likely implies wider utilization and a better understanding of the device’s potential in the coming years.

Next:Smaller incisionsSmaller incisions

When Clayman and colleagues reported the first laparoscopic nephrectomy, they utilized three 11-mm and two 5-mm trocars(J Urol 1991; 146:278-82). Many minimally invasive surgeons still use similar-sized laparoscopic ports today, even though 2- to 3-mm laparoscopic instrumentation exists. Most current da Vinci instrumentation works through 8-mm ports, although 5-mm instrumentation is available in limited selection.

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The pinnacle of minimally invasive surgery is the incisionless procedure, although the feasibility has been questioned. Natural Orifice Transluminal Endoscopic Surgery (NOTES) achieved that goal, but adoption was limited to experimental animal studies due to technical difficulty. Perhaps magnetic surgical instruments are a more realistic alternative.

The Levita Magnetic Surgical System works as an intra-abdominal retractor anchored via an extracorporeal magnet (figure 2a). The magnet can be placed on the abdomen or manipulated via an arm secured to the operating table side-rail. After grasping the desired tissue to retract, the bedside assistant separates the clamp from the introducer. The surgeon then controls where the retraction needs to be while the bedside assistant places the magnet at the corresponding extracorporeal location (figure 2b).

This device has FDA approval for robotic prostatectomy, and has demonstrated feasibility to manipulate and retract the colon, peritoneum, seminal vesicles, and prostatic capsule during neurovascular bundle dissection, and bladder during lymphadenectomy (Urology 2019; 126:237). While current technology is limited to retraction, the potential for a magnetic device to control a camera or a surgical arm might prove to be the epitome of incisionless surgery.

Next:Endoscopic robotsEndoscopic robots

Although endoscopic robots currently trail laparoscopic robot innovation, there is certainly optimism for the near future. Some might question the need for endoscopic robots given most procedures are naturally incisionless. However, optimizing ergonomics and improving instrumentation and functionality of endoscopes will not only improve the surgeon experience, but also expand the types of surgeries performed.

Most urologists would attest that ureteroscopy is often not ergonomically ideal. A robotic platform would certainly improve this. To date, the only functional ureteroscopic robot is the Avicenna Roboflex (ELMED), a robotic manipulator that adapts universally to any ureteroscope to remotely control deflection, rotation, insertion, and even irrigation and laser. From a procedural standpoint, the device is as miniaturized as current ureteroscope technology (7.5F-9.9F), although the current surgeon cart and robotic arm take a sizable footprint. Future applications would hopefully miniaturize this space, as well as the cost, which might be prohibitive for certain health systems.

While no true robotic ureteroscope currently exists, robotic endoscopes in other fields give promise to a future ureteroscope. Developed by Intuitive Surgical, Ion is a 3.5-mm robotic catheter that recently received FDA approval for bronchoscopy and peripheral lung biopsy (CHEST 2017; 152[suppl]:A858). It has 180 degrees of flexion and a 2-mm working channel. Visualization is obtained intermittently via a separate probe that fills the working channel. Auris Health Inc. is also developing a robotic endoscope known as Monarch, likely with similar functionality.

For this technology to accommodate ureteroscopy, simultaneous vision and a capable working channel is necessary. In addition, reducing the outer sheath size to be more in line with current endoscopes would facilitate adoption for retrograde intrarenal surgery.

Although transurethral resection of the prostate is the gold-standard treatment for symptomatic BPH, enucleation procedures (ie, simple prostatectomy and holmium laser enucleation of the prostate [HoLEP]) have consistently demonstrated superior outcomes. For HoLEP specifically, the learning curve is steep and performing the procedure through an endoscope sacrifices dexterity and fine positioning.

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Virtuoso Surgical developed a miniature two-arm robot that fits through the 5F working channel of a standard endoscope (figure 3). Initial experimental testing was promising, showing coordinated manipulation of the arms to allow for improved retraction and fine targeting of the laser fiber (J Endourol 2016; 30:692-6). The ability to perform complex movements allows for accurate endoscopic dissection in a more intuitive platform, which could broaden adoption of HoLEP and potentially even expand to bladder tumor resection as well as bladder and distal ureter reconstruction.

Conclusion

Continued development of the aforementioned surgical platforms will undoubtedly lead urologists to further minimize the surgical footprint. As more companies and collaboratives innovate and enter this market, we expect significant growth and continued miniaturization. Further, market competition might improve access to surgical robotic technology, which is often limited to more prominent health systems. While exciting, it is imperative that we objectively test this technology to truly understand the role in patient recovery and outcomes.

Justin Badal, MD

Noah Canvasser, MD

Dr. Badal is a resident and Dr. Canvasser is a minimally invasive surgeon and endourologist in the department of urologic surgery at UC Davis in Sacramento, CA.

Section Editor James M. Hotaling, MD, MS

Section Editor Steven A. Kaplan, MD

Dr. Hotaling is assistant professor of surgery (urology) at the Center for Reconstructive Urology and Men's Health, University of Utah, Salt Lake City, and Dr. Kaplan is professor of urology, Icahn School of Medicine at Mount Sinai, New York.