Single-port robotic surgery: challenges and opportunities

What is single-port robotic surgery and where did it
come from?

Single-port robotic surgery is a type of minimally invasive surgery (MIS) based on the principles of single incision laparoscopic surgery (SILS), which involves the use of a small incision and specialised instruments to perform surgery within the body. It is worth noting that the average size incision required for single-port surgery is 15 mm – 30 mm. This is a small incision relative to open surgery, but larger than the incisions required for multi-port procedures which require 3 to 5 incisions sized between 6 mm – 8 mm.

Photo depicting a multi-port surgical procedure

Due to the success of manual SILS procedures, a few pioneering surgeons began experimenting with the use of robotic surgery technology to perform complex procedures through a single incision. Initially, the technology was limited and the procedures were relatively simple, including cholecystectomies and appendectomies. As the technology advanced however, so did the complexity of the procedures that could be performed. The first single-port robotic surgery using the Da Vinci SP surgical system was performed in 2008 and since then, several other robotic surgery systems have been developed to perform single-port procedures robotically.

Today, single-port robotic surgery can be used for a wide range of procedures, including:

• Cholecystectomy (removal of the gallbladder)
• Appendectomy (removal of the appendix)
• Colectomy (removal of part or all of the colon)
• Nephrectomy (removal of a kidney)
• Hysterectomy (removal of the uterus)
• Myomectomy (removal of uterine fibroids)
• Gastric bypass and sleeve gastrectomy (weight loss surgery)
• Transoral robotic surgery (surgery for head and neck cancer)
• and general surgery (appendectomy and hernia repair).

According to a study published in the Journal of Laparoendoscopic & Advanced Surgical Techniques in 2018^[1], the most common procedures performed using single-port robotic surgery include hysterectomies (34%), nephrectomies (25%) and colorectal surgery (19%). As shown in the list above there is already an extensive list of procedures being carried out using single-port robots but as more surgeons gain experience with single-port robotic techniques, it is likely that the list of procedures that can be performed will continue to grow.

There are several singe-port robotic systems currently in development, however, the only single-port robotic system approved and on the market is Intuitive Surgical’s Da Vinci SP. It is the most advanced and widely used single-port robotic system, FDA-approved in 2014 for urological procedures. In 2019 the system was used to perform an increased variety of procedures including transoral. The Da Vinci surgical system is made up of up to three wristed instruments which achieve distal triangulation inside the patient’s body and a 3D, HD endoscope. The port diameter is currently 25mm.

The opportunities driving single-port robotic surgery

Instrument control

It can be argued that some of the key benefits driving innovation in robotic surgery are primarily for the surgeon. Compared to manual laparoscopy, surgical robots offer greater control, precision and less manual strain from poor ergonomics, as discussed in our blog on user-centred design for surgeons. There is still however considerable room for improvement in the surgeon’s ergonomic position while using a surgical console.

A key reason for this increase in dexterity is due to the fact that both single-port and multi-port robotic surgery (MPRS) allow for scaled movements. Many systems are clutch based, which enables the surgeon to make much larger movements on the hand grips than what is transmitted to the instruments, allowing for incredibly accurate, precise and calculated movements.

Single-port robotic surgery is also well suited to triangulation, a technique used in surgery to visualise a three-dimensional object from two-dimensional images. To achieve triangulation in manual SILS, where the instruments and scope all enter through a single port, surgeons are often required to cross their hands or instrument shafts, resulting in their actions needing to be translated. It can be helpful here to imagine one of the bicycles you see at a circus, as you turn the handlebars left, the wheel turns right. You can learn to do it and with practice it will become easier, but it is not an intuitive thing to do.

Single-port robotic surgery is perfectly set up to overcome this, as software compensation can invert and map the surgeons’ movements to allow for intuitive control of the instruments. This, combined with scaling, enables the surgeon to maximise precision and accuracy with simplified movements. These advances in technology have led to an increase in the number of robotic surgeries being performed, particularly in the areas of gynaecology, urology and general surgery.

Patient access

One of the key benefits of single-port robotic surgery is faster and easier access to the relevant patient anatomy through a single incision. The robotic instruments used in single-port surgery are designed to be flexible and manoeuvrable, able to reach all four quadrants of the abdomen from the umbilicus without being repositioned. This reduces the need to retract and re-port, helping to avoid potential procedural downtime. A single incision can also lead to several benefits for patients, including reduced tissue trauma, improved cosmetic outcome and a small reduction in recovery time^[2].

As single-port robotic surgery continues to be applied to more procedures, we can also expect to see decreased set up time as well, owing to increased standardisation in approaches.

Reduced learning curve and upskilling surgeons

A study conducted in 2019 found that learning to suture using robotic-assisted techniques was a faster process compared to learning manual laparoscopic suturing^[3]. Multiple studies have also shown that robotic surgery techniques level the playing field with regard to the required skills of the surgeon. One study found that the skill of the surgeon had little impact on patient outcomes when using robotic-assisted surgical techniques, with less experienced surgeons performing the same as higher skilled surgeons.

Interestingly, the study also showed that using a robotic surgery system could enable less skilled surgeons to perform comparably to the most skilled and experienced surgeons using traditional laparoscopy. A retrospective study from the University of Pennsylvania^[4] also looked at a variety of different procedures including prostatectomy, nephrectomy and colectomy, reiterating the finding that robotic-assisted surgery can be a helpful tool for less experienced surgeons to improve patient outcomes, compared to their manual laparoscopic outcomes.

The challenges impacting the use of single-port robotic surgery

Cost per surgical procedure

Despite the benefits surgical robots bring, multi-port and single-port robotic surgery can be costly to implement. These systems are state of the art, highly complex and loaded with sensors, resulting in a large initial capital investment.

Alongside initial investment, the cost of consumables must also be considered. To enable access through a single port for up to 3 instruments and a scope, some single-port robot system consumables are significantly more complex than multiport or laparoscopic instruments. If these modules are disposable or have limited reprocessing life and capability, this can enforce a higher cost per procedure and a significant environmental impact. Manual laparoscopy, in comparison, is generally less expensive, does not require specialised equipment and is more widely available.

Photo depicting manual laparoscopy

Training for surgeons

Training time is also incredibly relevant to the success and uptake of robotic surgical technology. Surgeons study for a long time to become qualified, after which they are then required to specialise and work under supervision before they can operate without support. Currently, any training required for a new robotic surgical system is in addition to a surgeon’s current training period.

While surgical robots may have the potential to enable less experienced surgeons to deliver higher quality surgery, the long and intensive training required still means taking the surgeon out of the operating theatre. Unless there are real reductions in procedural length following system-specific robotic surgical training, this will result in lost revenue for healthcare providers in the United States. In the United Kingdom it will make already growing waiting lists longer, putting additional strain on healthcare systems.

As surgical robot manufacturers begin to release more models based on the same underlying console, this could help reduce the need for retraining. For example, the Intuitive Surgical Da Vinci SP uses the same console as their multiport Da Vinci Xi. However, any novel systems from new manufacturers will still likely require additional training.

Proving patient benefit from single-port robotic surgery

While patient outcomes have been found to be similar across single-port robotic surgery, MPRS and manual laparoscopy, there is no definitive clinical benefit to single-port robots compared to the other techniques mentioned in this article. According to a study published in the Journal of Minimally Invasive Gynaecology^[5], patients who underwent single-port robotic surgery had a similar level of post-operative pain, hospital stay and recovery time compared to patients who underwent multi-port robotic surgery. While there is some data which claims multiport can lead to an improved cosmetic outcome, there is currently no correlation between this and faster recovery times.

A study published in the Journal of Urology^[6] found that patients who underwent single-port robotic surgery had similar outcomes, including a similar rate of complications compared to patients who underwent traditional laparoscopic surgery. It is important, however, to note that these studies were carried out with relatively small number of patients and therefore more data is needed to confirm these findings.

Incision size

There have been some concerns around the increased incision size required for single-port robotic surgery to allow for the insertion of the instruments and scope. Currently, port sizes are much larger than desirable in single-port surgery, with data to indicate that the larger incision required may increase the risk of hernia formation. For example, a study looking into the long-term incidence of incisional hernia after cholecystectomy in both multi-port and single-port robotic procedures, found that the hernia rate was 0.2% verses 4.5% respectively, 12 months post op^[7].

Private vs public healthcare

In the case of robotic surgery, the United Kingdom is still quite a long way behind countries like the United States, where robotic surgery is more commonplace in private practice. Adoption in the United States has been driven largely by patient desire to have a robot used for their procedure, meaning hospitals need to offer robotic surgical systems to stay competitive. In the United Kingdom, before a new surgical technology can be adopted, the cost benefit needs to be backed up with long term data. This is why manufacturers are introducing new initiatives, such as CMR Surgical’s charitable donation of a Versius system to Addenbrookes Hospital in Cambridge, to enable the generation of clinical data. This level of investment may not be feasible for smaller RAS manufacturers however.

The future of single-port robotic surgery

While the technology is impressive and the achievements of the engineering teams working on single-port robotic surgery are nothing short of incredible, the above challenges need to be overcome for the potential of single-port robotic surgery to be fully realised.

Unlocking new procedures

As noted, one of the biggest barriers to adopting robotic surgeries is proving clinical benefit over other forms of minimally invasive surgery. Further research will certainly be needed to establish the long-term benefits and risks of single-port robotic surgery compared to traditional laparoscopic surgery and multi-port robotic surgery. However, one of the most inspirational aspects of RAS is not its ability to improve clinical outcomes for existing procedures, but to use its capabilities to push the
boundaries of surgery – to use it to undertake procedures previously thought to be impossible with existing technology.

Reducing port sizes also has the potential to unlock new procedures and should be another key focus for surgical robotic development. It will certainly be interesting to see whether the technology is capable of moving towards a 10mm incision, which is seen as the acceptable size for other forms of MIS. This reduction in trocar size could further increase the number of procedures possible by unlocking ear, nose and throat (ENT) procedures as well as continuing to advance the systems’ offerings in natural orifice surgery such as trans-anal, trans-oral and gynaecology.

Reducing costs and improving access

Consumable costs and the environmental impact of complex single use components are another key concern for single-port robotic surgery. Manufacturers will need to consider system architecture designs that focus on the placement of the sterile barrier or drape interface, to retain high value components. This will also need to be considered in conjunction with designing the instruments to be easily re-processable with dedicated flushing channels. These steps would help to reduce the cost per procedure and improve the environmental and economic impact.

Reprocessing single-port robotic surgery instruments can also be a lot more complex than MPRS instruments due to the increased complexity and flexibility. Ensuring these points are considered early in the development cycle is crucial as re-designing and changing joint interfaces to account for this at a later date is a time consuming and costly approach.

Despite some challenges, the future of single-port robotic surgery is promising. With new technologies and techniques being developed to improve the capabilities of these robotic surgical systems, there is the potential to make the procedures more widely available. In the hands of the right surgeon, who knows what could be achieved using this technology?

References

[1] El-Tamer M, El-Khodary A, El-Khodary A, et al., “Single-port robotic surgery: A systematic review and meta-analysis,” Journal of Laparoendoscopic & Advanced Surgical Techniques, vol.28(1), pp.3-11, 2018.

[2] Carbonara U, Amparore D, Borregales LD, et al., “Single-port robotic partial nephrectomy: impact on perioperative outcomes and hospital stay,” Therapeutic advances in urology, vol.15,17562872231172834, 2023.

[3] Robotic-assisted prostatectomy versus open radical prostatectomy: a randomized controlled trial. The study was conducted by researchers at the University of California, San Francisco.

[4] Retrospective: The impact of surgeon skill on outcomes of robotic-assisted surgery: a retrospective analysis. The study was conducted by researchers at the University of Pennsylvania.

[5] Abolghasemi A.A, Esmaeilzadeh M.H, Ghasemi A.A, Sadeghi M.R, and Malekzadeh M.A, “Single-Port Robotic Surgery for Gynecologic Surgery: A Systematic Review and Meta-Analysis,” vol.24(2), pp.185-194, 2017.

[6] Gill J.B, Davis J.R, Wei J.J, Matin A.S, Eastham J.A, and Wexner S.C, “Single-Port Robotic-Assisted Laparoscopic Radical Prostatectomy: A Multicenter Study,” vol.189(1), pp.126-131, 2013.

[7] Jensen SAS, Fonnes S, Gram-Hanssen A, Andresen K, Rosenberg J, “Low long-term incidence of incisional hernia after cholecystectomy: A systematic review with meta-analysis,” Surgery, vol.169(6), pp.1268-1277, 2021.