Robots are helping surgeons, but so can user-centred design

16 Feb 2023 17min read

Modern surgical robotics are changing the way we approach healthcare, enabling surgeons to perform minimally invasive procedures with greater ease and accuracy. These systems are incredible for helping to reduce the physical demand on surgeons too, reducing the risk of work-related injuries due to poor ergonomics – an issue that currently impacts around 80% of surgeons.

Despite this, surgical robotics remain a costly option, especially for developing countries. They are also not yet suitable for all procedures. The benefits that robotics offer to surgeons raises an important question however – can we improve the usability for existing surgical devices to give surgeons the same physical relief they are seeing from robotics?

Understanding the surgeon's context of use

In order to develop the right solution for surgical equipment, the key is to understand the surgeon’s context of use and the steps needed to treat patients. When developing medical devices, there can be a tendency to focus on what the device is providing for the treatment, therapy or diagnosis. This is usually the core reason for the inception of the technology and should be one of the main considerations. However, if, to provide the treatment to the patient, the surgeon needs to apply a very high force, hold their body in an uncomfortable position for prolonged periods of time, or perform an action which is not intuitive, there will be unintended consequences for the main user of the device – the surgeon. With this in mind, every aspect of medical device usability in a surgical setting requires careful consideration.

I posed this challenge to some of my colleagues: how would you approach surgical instrument design for open or non-robotic minimally invasive surgery to minimise the impact on the surgeon during its use?

The resounding answer was that to understand a problem fully, and to identify opportunities to solve that problem, the development team needs to observe intended users performing the surgical procedure in question. Undoubtedly, the best way to do this and have confidence in your insights is through observation in a user study.

Unfortunately, observing a surgical procedure is not easy, with data protection regulations hospital regulations and other factors often at play. The next best thing is user observation, where the procedure is performed on a real or synthetic cadaver. If all observation options are not possible, interviews with a range of surgeons should be conducted. It’s important to note, however, that issue identification from interviews will not be as rich as observation. Quite often, users are not aware of everything that they are doing in actual practice, or the external factors which may affect them during surgery. Therefore, asking them to recollect these important factors later may not yield every key detail.

Minimally invasive surgery Adobe stock 244344536

“Watching people is three times as valuable as listening to them.”

Diane Aston-James, Human Factors Director

What makes a successful surgical user study?

If the facilities and resources are available, there are several key elements required to ensure a successful user study which will accurately inform the development of your surgical technology:

1. Objectivity

A quality human factors user study output must put preconceived ideas about solutions and their issues aside. The aim is to look for every opportunity to design a device which enables a surgeon to effortlessly perform their procedure. If the development team approaches the study with preconceptions or a key cause they wish to address, other opportunities may be missed. The art of Human Factors Engineering is to remain impartial and to observe as much as possible without applying any influence.

Another element of objectivity which needs to be maintained is the participants in the study. Quite often, a medical device developer (whether that be a start-up or multi-national organisation) will have a key opinion leader or a surgeon who is known to them. The best participants to have in your study are those who have no affiliation or vested interest in the technology being developed. Observing a range of objective, un-biased users will give you accurate insights to inform your medical device usability development and ensure you are solving the real and most important problems.

2. Accurate representation

Having a variety of people in your study is critical. Not everyone will face the same problems when using your device and to understand the range of issues, one must consider a range of users. From our experience, the key differentiators are related to anthropometric size range, geography and hospital type. There are several key questions to ask related to these differentiators. Who will use your device? In which countries and hospital/clinic types will your device be used? If 90% of your users will be women who are based in either Germany or the US for example, you need to ensure the users in your study reflect this.

Representation should also be extended to the patient being operated on. Patient size and position will affect what the surgeon does to perform the procedure. For example operating on an obese adult patient is very different to a child.

Drawing insights from a user study to improve surgical
device design

The aim of the user study is to identify all potential opportunities to improve the design of a surgical instrument or technology to benefit the surgeon during their procedure. It is therefore important to ensure that all factors which could influence this are observed, including:

1. The environment

When it comes to a surgical procedure, surgeons can be influenced by the environment around them. While it may not be in your scope as a device developer to change elements of the environment itself to improve the surgeon’s experience, the design of your technology or instrument could still be improved to account for them. Some key factors to consider are:

  • Lighting – can the surgeon see what they are doing? Poor visibility can lead to fatigue through requiring greater concentration and prolonging the duration of the procedure. Can the design of your device be altered to ensure that it can be easily seen? Or can the form or physical feedback be optimised so that it does not need to be seen to be used correctly?
  • Noise – does this distract the surgeon or make a key function of the device not possible? Does the surgeon use sound as an indicator for what they are doing? Can this noise be harnessed, enhanced or simply retained, ensuring your device does not interfere with this?
  • Table height and patient position – how does this influence the position of the surgeon’s arms? If the device is designed assuming that the surgeon’s arm is in a position which differs from the reality, this could cause strain. Can the interface between the surgeon and instrument be optimised to account for the position of their body?
  • Humidity – the pneumoperitoneum during laparoscopic surgery can be very humid which can cause difficulties during procedures for haemostats, for example. Is this adding unnecessary steps or challenges to the procedure? Is humidity affecting visibility which is increasing the time required to complete the procedure? Humidity, combined with bodily fluids and gloved hands, can make gripping instruments difficult. Is there a lack of secure features on existing devices, meaning the surgeon needs to use two hands instead of one? Are the surfaces of the device so smooth that gloves slip on them? Is there a build-up of tension in their hands due to the device not feeling secure
  • Other surgical staff – does the procedure require lots of different staff to be around the patient? If so, this may reduce space the surgeon has to operate. Does this cause them to adapt their body position? Are existing instruments too large or too long to operate easily in a crowded theatre? What is their interaction with the surgeon? Can the instruments be easily handed over? The answers to these questions should all be considered in the usability testing of medical devices, particularly with regard to surgical tools.

2. The surgeon

There can be a tendency when observing a surgeon performing a procedure to watch the area they are operating on and their hands whilst they do it. However, this is only a small piece of the puzzle when identifying opportunities to reduce fatigue. As with the surgical environment, the surgeon’s entire body needs to be observed. The key things to observe and monitor when assessing surgical and medical device usability are:

  • Posture – this can be evaluated using a Rapid Upper Limb Assessment (RULA) to determine whether the surgeon’s task is causing unwanted strain. An RULA considers biomechanical and postural load requirements of tasks and their impact on the neck, trunk and upper extremities. The surgical instrument design can then be tweaked to encourage a posture which has a lower RULA score.
  • Forces – are there any functions of existing instruments which are difficult? Are all users able to comfortably use them? This is another area where anthropometrics is key. Not all users will have the same strength or size of hand to apply the force comfortably. Even if they canactivate the instrument, the force to do so may not be acceptable to apply repeatedly. By using anthropometric data, a force can be targeted which is reasonable for all potential users, thereby reducing surgeon fatigue.
  • Pain points/feelings – sometimes visual observation alone does not reveal the full picture. A key role of the moderator in a user study is to ask the surgeon questions which enable them to answer without influence. There may be parts of a procedure which the surgeon finds particularly difficult or stressful which are not immediately obvious to those observing. These ‘pain points’ are extremely useful to help identify which parts of the surgical instrument design the development team should focus on to improve the surgeon’s experience during the procedure. Tools such as the Nasa TLX can also be used to determine cognitive workload on the user for different tasks, to help prioritise specific areas of the procedure to focus on.
  • Focus – where is the surgeon looking? The focus of a procedure should be the patient. Are there tasks which distract the surgeon or cause focus to be taken away from the patient? The surgeon’s eyes are a key indicator for this. Tools such as Tobii wearable eye tracking software can be used to monitor what the surgeon is focused on. If parts of the instrument are causing the surgeon to take their focus from the patient, these may be opportunities for medical device usability improvement.
Human factors camera observation

“Tracking eye movement won’t necessarily tell you anything new about what the problems are, but it may tell you why they occur.”

Paul Greenhalgh, User Experience and Innovation Director

After the user study is complete, the outcome should be objective un-biased data, such as video, photo and sound recordings, which aren’t anecdotal and have no suggestions for solutions – they must be agnostic. The output from each user touchpoint can then be rigorously analysed to identify opportunities to improve the surgeon’s experience throughout the surgical procedure, which can then be fed into the user requirements.

“It’s data, not just anecdotes; we bring the science to what people do.”

Derek Dumolo, Senior Human Factors Engineer

Understanding the problems users face in such detail, especially at the start of the development, gives the best chance for your technology to solve real user problems, increase market adoption and ultimately delight your end users. Once these opportunities are identified, concept creation can begin.

Creating a concept for your surgical device

The concept you develop will be dependent on the types of challenges you are addressing and the constraints they bring. An effective design team will take the qualitative data you have gathered and turn it into something physical which can be used and measured. The following are some of the key factors to consider when creating a concept:

1. Work within the creative limits

Our aim in this instance is to develop an instrument which reduces the strain experienced by surgeons when performing a specific procedure, without impacting the patient. The concepts created to achieve this must however be developed within the bounds of creative limits.

“Concepts need to address problems within acceptable creative limits. We have levers we can play with within strict boundaries.”

Tom Etheridge, Senior Design Consultant

Creative limits are external factors which are key to the success of the device. For example, cost is critical for technologies which are to be used within the National Health Service of the UK, which can limit the viability of some solutions. If a user study identified that surgeons experienced fatigue when using a scalpel for an hour during a procedure, an augmented arm would be a possible solution; however, it would be far too costly for widespread implementation in the NHS. Other creative limits may be materials, performance, or size. Concepts must both address the problems identified in the user study, whilst remaining feasible for their intended purpose.

2. Go unnoticed!

Many surgical instruments in use today have not changed for hundreds of years. Surgeons have been trained to operate using these tools and often have many years of experience using them. Innovation in surgery needs to bring new benefits to the user whilst retaining familiarity – you don’t want the surgeon to have to spend time learning how to use the instrument or create a sense of uncertainty while in the operating theatre. If you double the size of the grip of an instrument to improve ergonomics and comfort, for example, you need to consider if this has altered the instrument so much that it no longer resembles the original.

Good design is intuitive and purposeful. The semiotics of the device need to communicate to the user how it should be used. If the user is required to do something to activate a feature of the device, it should be an obvious and logical action to achieve the desired result. I have witnessed first-hand a product concept be thrown across an operating theatre because it did not instantly work for the surgeon. Instruments need to be safe, reliable and work how they are expected to the first time a surgeon picks them up.

As with the look and feel of the instrument, reliability is key – not just for patient safety, but for the surgeon’s experience during use. All medical devices should be underpinned by sound and reliable engineering to ensure the instruments work throughout the lifetime of the device. A surgeon can achieve a lot with their hands and some stainless-steel instruments which have not changed for hundreds of years. If your device is going to be used and trusted, reliability is absolutely critical.

“Good design goes unnoticed but bad design stands out like a sore thumb – the goal is the surgeon doesn’t know they’re using it.”

Steve McLellan, Senior Design Consultant

3. Design it for the body

As discussed in the approach to a user study, what the surgeon’s body is doing whilst using the device is key to how comfortable they are. Your device can be designed to encourage the surgeon to adopt a less strenuous posture, or to fit the surgeon’s body so that it is comfortable, intuitive and easy to use.

The key to this is a combination of anthropometrics and ergonomics. Using data, you can ensure that the handle of an instrument is designed to fit the grip of all potential users, or that the mechanisms used to activate it are within an acceptable force limit for repeated use.

Creating concepts is the second step in your early development journey; however, it is certainly not the last. You cannot judge the success or failure of these concepts based solely on data from an initial user study. It is critical to get models of the concepts you have used back into the hands of potential users as soon as possible.

Multiracial team of professional medical surgeons performs the surgical operation in a modern hospital. Doctors are working to save the patient. Medicine, health, cardiology and transplantation.

Iterative evaluation of your medical device concept

The influence of the user study should be prevalent throughout the design of your concepts and throughout their iteration, with an ever-present team member who is the champion for the end user. The interpretation of the output of the study should be considered and represented to ensure that concepts stay aligned with the needs of the surgeon and continue to address the problems facing them during the procedure.

Once your concepts have been developed into functional concept models, it’s important to test them iteratively with users in their real (or simulated) environment to ensure they solve the challenges you set out to address. As a device developer, you need to ensure that your new device hasn’t caused new problems by solving old ones. For example, if you have designed your device to encourage the surgeon to adopt a less strenuous position when operating, has this had unintended consequences? Can the surgeon still use other systems they use in partnership with this new instrument? Or is it now incompatible?

Some things are hard to quantify, so if you have set out to make the device intuitive or comfortable, you need to validate this. This evaluation should not be on a single concept, but several. User studies take time and cost money, so going to users early on in your development with a single concept will likely yield a binary response – it either is or isn’t intuitive to use. Having several concept variants will aid users to articulate the pros and cons of each concept and enable you to identify what makes a concept more intuitive and which concept, or aspects of your concepts, to progress further. Sometimes, the best medical device or surgical instrument design can be a combination of previous concepts.

As noted, during the user study you should make sure that you are observing the surgeon in a representative environment. This is equally important for testing concept models. However, for the rapid iteration required for early phase concepts, the costs and lead times associated with a user study may be unviable. This is where the development of a rig (custom machinery developed for testing) or use of a specialist laboratory can be extremely useful. Rigs can be specially developed to simulate surgical conditions and enable regular and robust testing of device concepts. If environmental conditions are key to accurately assess your device performance, environmentally controlled labs should also be used.

The combination of this type of testing, in addition to quantitative data capture, is key to the success of your device. Without regular interaction with users and testing in a representative environment, developments can stray and fail to meet their original objectives.

User-centred surgical tools

Despite advances in surgical robotics, open surgery and other minimally invasive surgical procedures will continue to be required for surgeries where robots are not an option and for countries where the cost is too high. To reduce surgeon fatigue and discomfort and attain similar levels of user benefits seen in robotic systems, a user-centred approach to device development is key. Observation of the procedure should be undertaken as early as possible to ensure that opportunities for improvement are identified and implemented into the device requirements from the start of the development.

By interpreting the outcome of the study and combining user centred design with robust engineering, device concepts can be created which are intuitive, comfortable, and reliable. These should be tested iteratively throughout the development with real users to validate that they meet initial requirements set out by the first user study.

Safety, reliability and regulatory compliance are non-negotiable for any medical device development. However, by following a user-centred design development approach, you can ensure that when your device gets past the regulators and is out in the market, it is not only commercially successful, but loved by your end users and provides a benefit to them as well as the patient.

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