Pros and Cons of different soft tissue surgical robot architectures
- Steve Bell
- Feb 27
- 15 min read
Updated: Aug 28
I’m often asked to give an opinion on the benefits, pros and cons of the different architectures of soft tissue surgical robots. Today I’ve dropped a categorisation of the different architecture types with my opinion on this. Having now driven many of the robots out there, been in hundreds of procedures - this is how I see them as of today.
Of course under these categories there are many different companies making their robots based on these architectures. If you want the pro and con of up to 60 different systems they are in this list here — https://www.howtostartupinmedtech.com/post/version-2-ultimate-soft-tissue-surgical-robot-comparison-chart
But for today you can understand the basic architectures and the pros and the cons by architecture type (as I see it.)
Boom Multiport
Many think this is the “original” format of soft tissue surgical robots. But little known fact... the bed mounted ZEUS by computer motion with its small modular arms came out at the same time.
The boom structure - like this DaVinci 5 - work like a tree. It has a big base and a central trunk which each of the arms hang from. They can be side loaded arms or they can have an X beam architecture where the arms come off in a Sort of cross on a swivel which allows better access in multi quadrants. Different companies have different ways they implement this - but this is the basic architecture., A single boom with the arms hanging off the boom.
Pros
These systems are generally very big and very heavy which makes them incredibly stable and reduces tremor or unintended movement. They generally have a lot of reach and can get to most quadrants from that one position.
They are generally considered easier to set up - as if you follow the set up guide you end up with just one base to place and then everything is in relation to that single base. This often makes the set up more “repeatable” so you can end up with simplified standardisation.
As this is the “market leader” with about 98% of the installed bases - then of course from a familiarity point of view - most people will know this boom architecture. Again making it easier to get up the learning curve - especially for the bedside teams.
Cons
That mass is all concentrated on one spot on the OR room floor. And as they can be hundreds of Kilos - then that can cause concerns about the structural integrity of the floor and weight bearing. The problem is that the weight is very concentrated in one spot.
The arms all being on one boom mean that even folded down - many of the systems are still very bulky as a single item. That can be a problem for transport between ORs and storage. Often meaning that boom robots stay fixed in one OR - and often a big OR.
The ease of set up does come with some downsides. The ports in the patient need to be ideally placed in relation to the fixed arms. (I use fixed in a strange way here as of course they move). But generally the geometry of the arms is all from one fixed physical point of the boom source. The X boom and joints help to give spacial separation - but ultimately the fixed single boom becomes a determinant of the geometry of the arm set ups. So port placement ends up with some limitations in certain set ups. The user must adapt to the boom. And laproscopits purists don't like that.
Modular Multiport
This design is where you mount single or multiple arms onto some form of small modular carts. A well known system is Medtronic HUGO. Each bedside cart holds an arm that holds the instruments. Each cart can then be positioned anywhere around the patient for many different approaches.
Pros
In one sense this is much closer to how laparoscopic surgeons work and think. They put the ports where they want (there are exceptions of port spacing with some systems) and then they bring the arms to the ports. Just as you would in laparoscopy.
As you have a freedom of where you position the bases - you can tailor the set up to meet your operating style. It gives a sense of more freedom of choice in how a surgeon operates. You can even choose to use less arms if you want or need. Or more if you need more - up to 5 arms with some systems like SSi Mantra.
Each cart is a smaller module as it only has one arm per cart (well most systems are built that way.) That means they are lighter and smaller than any booms. That means they are often smaller and more portable than a single big boom. Note - even though the total weight can be more than a single boom (say 4 arms and carts combined) it is spread over a much larger surface area - so the amount of pressure one the floor is often less. A lot less with smaller modular systems. And individual components can in some systems be moved between floors in standard elevators.
Cons
The smaller bases can end up, if they get too small, to have limitations of reach and stability. The trade off becomes that if you make them too small they wobble - if they wobble you may need complex software control systems to stop unintended motion at the instrument tips.
Although modularity allows flexibility and choice. The choice can become overwhelming and even confusing. It can cause each operation to feel like you are starting to learn from the beginning again where to put the carts. And if you get it wrong it can mean you need to move the carts time and time again during a procedure. That can frustrate and prolong the learning curve with modular systems.
With each cart there can be a cable or two or three. The carts can become a mass of jumbled spaghetti and trip hazards for the staff. This can become annoying for bedside assistants. And they may already be annoyed by yet another set up variant that was tried that day.
Although lighter and more compact (for most systems) if you move a boom between ORs, you move one boom, one console and one tower - so three components. With a modular system you can end up moving all those arms (and cables) and end up with six or more components to move between ORs. More mobile? Depends how you see it.
Bed mounted multiport
Much as everyone thinks JNJs Ottava is a revolution here - it’s one of the original ideas of Computer Motion and Zeus back in the late 90s - which was later abandoned. There are a few other bed mounted systems that have been used and abandoned and few in development - and a few in commercial use. The idea is that the bed becomes the base of the robot in effect. The arms come from below or along side the patient and when you move the bed you move the robot.
Pros
In some ways this should mean there is no bedside boom or cart on the floor. Often called Zero footprint. The idea of not having and extra piece of equipment (boom) or several carts (Modular) means set up and workflow should be easier with no need to bring the systems to the bed.
If the arms are mounted to the bed - then as the bed moves for patient positioning - the arms move with the bed (twin motion) and that means gravity can be used to reposition the organs of the patient and assist the robot arms. With some systems they need a special bed that is connected by software to the robot boom. Or it means taking instruments out of the patient for most other systems while the bed is tilted.
Storage will be a lot better as the arms of the robot store under the bed. And if the robot is kept in the OR then effectively it has no storage space for the bedside components. So could be ideal for smaller ORs
Less set up and cabling. This is because all of the control cables are in the bed unit so there are no wires to trip over from each of the arms. There are no base units for a bedside assistant to trip over. Effectively it frees up space and complexity around the table.
Cons
Even with an 8th degree of freedom joint - the integrated bed arms create a limitation on the position of the arms. As there is no “swivel” in relation to the patient it can mean that reach and position can become limited in some patients and some procedures. Multi quadrant can become challenging.
The cage effect. Probably one of the biggest fears of for any robot is that it goes into a high priority alarm and locks up around the patient. With non bed systems the robot can be moved away to get access to the patient - especially in an emergency. With bed mounted, the bed an patient are locked together. So the patient and robot are locked together. That can be an issue for patient access in such an event.
Workflow. Not all ORs around the world work the same way. Often the anaesthesia regimes are different - and induction happens in a different room and the patient is brought in on the bed. That can be an issue in some places as you cannot set up the arms and drape them ahead of the procedure. It can also tie up the robot so turn over cannot happen as fast as with other systems.
Twin motion or bed motion is great in theory - and to some degree can work. But in extremes of head up of head down if a patient were to “slip” with instruments still inside - it could be disastrous. So caution on how extreme a patient can be moved must be taken.
One of the biggest downsides is that “you need the specific robot bed” and many people have firm choices on the bed they want and supplier contracts. It also means that the robot is blocked to that bed and that can literally block the robot in a room as the robot cannot be moved until the patient is off the table.
Mini RAS
Mini RAS is so far occupied by one manufacturer - Virtual Incision. But others are in the works. This is the idea where the entire robot is a small system where most of the motors and drive system are actually placed into the patient. The idea is being small - compact and always ready to go as it is sterile.
Pros
It really does make any OR robot ready. You take it from the tray - place it in the patient and fix to a small bed frame. No bedside unit and no draping and set up. It’s all self contained.
The simplicity of the system and delivering the robot arms and motors inside the patient means there is literally no movement or clash possible outside the patient. Everything is happening inside the abdomen. Airspace around the patient is incredibly free.
Transporting the system is easy - it is just a small control tower and console. The robot itself is tiny and fits in s small tray. That makes sending it to remote sites easy - and there is no classic on site servicing of the bedside unit. It makes things simple.
Instruments are simply “tips” as the robot is the instrument in many ways - a very different way to approach the issue. Economic, less waste and allows a new instrument tip every case.
Cons
To get all that technology inside the patient requires a relatively large diameter incision (today) and that limits it to the practicality of procedures where a specimen will be removed from the incision - such as colorectal.
You are limited to two robot arms and that means the use of a bedside assistant and port - so it is not a single port and not a multiport. That can be hard to understand for many surgeons.
There are some limitations the ability to get counter traction using the robotic arms - so reliance comes on a good bedside assistant. And although strong, there are limitations of just how much organs can be lifted over larger distances.
Today 2D visualisation and not true endowrists make some robotic users feel it is not as capable as a boom robot. The concept needs to some adjusting to.
Single port
This is an evolution of a technique known as SILS - Single Incision Laparoscopic Surgery.
A laparoscopic technique where a single large umbilical incision is used and a single port is placed where multiple instruments can pass through. The advantage of the robot has been the development of snake like cameras and instruments - with semi wristed instruments
Again most current single port systems like the DaVinci SP are a single boom with three instruments and camera all hanging from the one boom and placed through a single trocar.
Newer systems are in development like Vicarious Surgical which aim to reduce the incision size by having a step wise introduction of the camera and then only two instruments.
However the idea is similar to SP, with a single incision and procedures done through that incision.
An extension of single port has been the use of the systems in transoral and transanal where the small diameter of the natural orifice makes it convenient you use a single port rather than a Multiport system. The ability to "elbot" in the mouth or rectum is a useful feature you do not get with multiport - straight instruments.
Pros
Less incision leads to less pain and less chance of either infection or port site herniation. Less incisions lowers the risk of puncturing something in the abdomen with each trocar insertion.
Single ports all but eliminate arm clash - well because there are no arms as such.
Single port technically makes multi quadrant easier as all four arms (instruments and camera) move in parallel as you move the SP from quadrant to quadrant.
Compared to the manual SILS - you are no longer crossing instruments at the single site so movements via the robot are easier and more natural.
If you can drive a da Vinci Multiarm - you can more or less drive a single port
It is ideal for bringing robots into natural orifices.
Cons
Getting large scale retraction is an issue, so often an ancillary post is needed - making single port become not single port.
Today no single ports have advanced energy or stapling so have limited appeal.
There is less strength and grabbing power with the smaller flexible instruments.
The wrists today are nor real end-wrists - so some manoeuvres like suturing are more limited than with a multiport with genuine end-wrists.
Costs - it is juts more expensive to make the instruments so each case costs more.
The large single port is a major concern for port site herniation - even if at the umbilicus - it is a big incision relative to a number of 8mm Multiport incisions.
Advanced Assisted Laparoscopy
The concept here is to not head to full robotics with fully wristed instruments. (Although some new systems like Revolve Surgical from Canada do bring a sort of wristed instrument to the advanced lap robot) and of course there are fully wristed and flexible manual laparoscopic instruments - various companies make them.
With companies like Moon Surgical the aim is to bring the power of the computer, the assistance of robotic arms to the table and the OR but keeping the surgeon at the table doing laparoscopy manually. It is about upgrading laparoscopy - not doing seated robotic surgery.
Pros
Many procedures do not merit the full set up and expense of a fully capable da Vinci like robot. Sub 30 minute procedures - often lap is good enough. But you want digital assistance... and these systems deliver.
By bringing in two robotic arms that are cobotic - they surgeon can all but eliminate one of the bedside assistants. This is the massive saving for stretched health systems. As an aside it is often better at holding the scope as it is “stable” all the time.
It allows a hospital to use its current vision system - with no need to buy a new one. It also allows a hospital to use their regular lap instruments - so saves on expense.
It has a relative small footprint compared to main frames - as it has no console.
It keeps the surgeon sterile so they can solo operate - important for various care settings such as ASCs. It improves efficiency whilst removing dedicated staff needs.
It's laparoscopy - so training is negligable - and learning curves are very fast.
It provides tons of data and exploits the “computer” in the room theory that it though to be one of the most valuable attributes of any robot.
Cons
For many it is not a “full robot” and they want to be away from the table at a console with full control of the robot arms and camera. Many don’t want lap 2.0 they want robotics as per the da Vinci paradigm.
There’s no dedicated 3D imaging system that many people want - although a 3D laparoscope can be used - but that is often an extra upgrade for the hospital.
No wristed instruments - it relies upon standard straight stick instruments and for those that want robotic wrists it does not bring enough to the party. You could technically use something like an Artesential - but now people will ask - “why not just get a robot”
Endolumenal robotics
Taking the single port paradigm to the extreme you put a robot on a flexible delivery system. This can be to improve diagnostics such as Bronchoscopy with Ion & Monarch. Or it could be to do urological procedures such as PCNL. Or to the extreme of endolumenal surgical procedures with Endoquest for EMR and ESD.
Pros
These systems can get deep into the structures of the lung, urinary tree or bowel with steerable and navigated guidance. When they get to the site they have a stable platform to deliver biopsy, laser or full articulating and controllable robotic instruments. Stability is key.
Makes the ability to do more complex procedures at a distance with flexible scopes. A user can be more adventurous by having robotic tip control of "long catheters." this brings a new level of precision.
User can be further away from the patient and control the catheters via controllers or consoles. If the procedure requires fluorescence it can limit the radiation doses to users.
It puts a computer between the user and the patient which helps with control, preoperative guidance and post operative data.
Cons
Very procedure specific and not super generalistic platforms. Even variants between bronchoscopy and urinary procedures are quite different with Monarch.
Limited strength when used in endolumenal procedures - just by the nature of design. This can limit the number of applicable procedure types.
Larger footprint than navigation or endoscopy alone.
Catherter costs vs standard reusable bronchoscopes / endoscopes are more and the economics can be challenging.
Automated procedural robots
This is a catch all of procedure specific robots such as Procept, Focal one and others. It is using the sense of robots to create automated movements of either probes, or needles, or catheters for specific therapies such as BPH (Benign Prostate Hyperplasia)
Pros
Dedicated robot that focuses on treatments such as BPH. Very focused use of a robot.
Minimally invasive procedures vs more invasive procedures because they are robot enabled.
Removes operator variability by taking the human “user” out of the pathway movements of the catheter, probe, hook, etc. It standardises movements. Very important for procedures such as HoLep lasers fro prostate.
It allows degrees of autonomy such as with Andromeda Surgical and the autonomous HoLep approach to prostates.
Adds navigation and compute power between the user and the patient. Allows data collection - feedback and learning to power algorithms to get a feedback circle of improved outcomes.
Cons
Dedicated robot for a dedicated procedure - you need to buy that robot - “Just for that.”
Some people doubt the benefits of bringing a “robot” to such procedures and feel that manual interventions are just as good - and do not see enough clinical evidence of benefits. Lots of alternative minimally invasive therapies.
Expense vs a simple procedure - so therefore reimbursement can often be a barrier for these new robots.
Open Micro Surgical
A growing segment is that of applying robots for open surgery. Be that in ocular surgery - micro vascular surgery, micro neuro procedures - breast flap reconstruction etc. These robots have small short instruments - that are designed to replace microscopes and manual micro instruments in many procedures. This includes MMI, Microsure and Sony in the segment and several ocular robots like Precyse.
Pros
Tremor filtering and motion scaling combined with robotic magnification exoscopes means that the surgeon can be very precise with micro surgery - with large hand movements that are translated into the small micro instruments.
Higher likelihood of a better anastomosis by many more users - it will level the playing field by using mechanics as a leveller in these intricate procedures.
Wristed instruments mean attaining ottomy angles and suturing anastomosis including knot tying of small gauge sutures is assisted and simplified.
Cons
Increased expense of adding in the robot and in some cases single use instruments vs traditional hand held reusable instruments.
Large size of the system adds a lot of “metal” into the operating room.
Set up times are not that long but it does add extra set up and position of the arms.
Limited instruments available today do limit the procedures somewhat in terms of what the robot can actually do.
Others
There are other categories of soft tissue robots - such as Histosonics and others. I’ve decided not to cover every variant today but the ,most common with a few variants within a category.
It is also a little difficult to be specific when I’m talking categories - as each robot is so different - even within categories that it becomes a little generic.
If you want to dig deeper into the pros and cons of each and every system in soft tissue robotics - then please sign up to the “The List” which lists them out one by one - gives full details of the systems and the pros and cons of each individual system - Link here >> https://www.howtostartupinmedtech.com/post/version-2-ultimate-soft-tissue-surgical-robot-comparison-chart
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