Robotic surgical spine systems, China, and machine learning

  • Robotic surgical systems have gained a small but significant share of the surgical spine market and assist surgeons to improve accuracy and patient outcomes
  • The industry has been dominated by Western corporations and benefited from advancing technologies, ageing populations with age related spine disorders and the need to reduce costs
  • High costs, training and the cumbersome nature of the systems are frequently cited as obstacles likely to slow the adoption of surgical robotic systems
  • Over the next decade expect competition from China’s emerging robotic surgery industry
  • Systems are expected to become smarter and more autonomous
  • Greater autonomy raises an “interpretability challenge” not broached in surgical studies, but likely to be a more significant obstacle to the development and adoption of robotic surgical systems
  
- Low back pain and the global spine industry -

Robotic surgical spine systems, China, and machine learning
 
Over the past two decades many spine companies have pursued a strategy of incremental innovations of their existing product portfolios to launch ‘new’ offerings at a higher price point. This has served the spine industry well by providing producers with relatively stable revenues and protection from a sudden loss of market share, such as that experienced by pharma companies when their patents expire. The disadvantage of such a tactic is that it encourages a mindset focussed on profit margins and revenue growth rather than on strategic issues and enhancing value for patients. In today’s increasingly value orientated healthcare ecosystem driven by high and escalating healthcare costs, more stringent reimbursement policies, tougher regulations, advancing technologies and increased competition, it seems reasonable to suggest that incremental fixes to existing products are unlikely to return spine companies to the high margin profitable growth businesses, which they once were.
 
Today, healthcare systems are looking for more disruptive technologies to provide them with cost effective, high quality, affordable surgical spine solutions for the vast and increasing aging populations with degenerative disc disorders. This has created an opportunity for robotic surgical systems to gain a small (<10% of lumbar procedures), but significant share of the spine market. Robot-assisted spine surgery, which aims to automate repetitive tasks and improve the quality of patient outcomes, is being championed by some healthcare professionals as a potential paradigm altering technological advancement. Systematic reviews and meta-analyses have found that clinical benefits of robotic surgery, compared to laparoscopic surgery, include less blood loss and shorter hospital stays. Compared to conventional open surgery, evidence indicates robotic surgery holds potential for smaller incisions with minimal scarring and faster recovery.
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Since the widespread dissemination of minimally invasive surgical modalities, a critical mass of physicians appears to have enthusiastically embraced robotic-assisted surgery. A cohort study published in the January 2020 edition of the Journal of the American Medical Association used clinical registry data from the US state of Michigan from 1st January 2012, through 30th June 2018; comprised of ~169, 000 patients across 73 hospitals. The average patient age was ~55 and ~54% of the cohort were women. The study found that the use of robotic systems for general surgical procedures increased from ~2% in 2012 to 15% in 2018 and concludes that the introduction of robotic surgical systems has been, “associated with a decrease in traditional laparoscopic minimally invasive surgery”. According to ResearchandMarkets, a leading market research firm, over the next decade, the global surgical robotics market is projected to grow at a compound annual growth rate (CAGR) of ~10% and reach ~US$17bn by 2031 from ~US$5.5bn in 2020.
 
In this Commentary

This Commentary describes how robotic surgical systems have been enthusiastically embraced by a growing number of spine surgeons but draws attention to studies that suggest obstacles to the widespread adoption of surgical robots. These include costs, training, set up time and their somewhat cumbersome nature in the OR. We describe a significant tailwind and a countervailing headwind for the further adoption of robotic surgical systems. The tailwind is the significant investments being made by China in the development of robotic surgical systems. The headwind is an ethical issue associated with the increased use of AI and machine learning algorithms, which are likely to make surgical robots more autonomous. Before discussing these issues, the Commentary describes: (i) robotic surgical systems and spine surgery, (ii) two categories of robotic surgical technologies, (iii) the principal robot systems that are currently in clinical use, (iv) the critical nature of training, (v) China’s increased investment in the development and commercialization of surgical robots, (vi) the ‘interpretability challenge’, which could become a more significant obstacle for the further adoption and increased automation of robotic surgical systems in certain regions of the world.
 
Robotic surgical systems and spine surgery

The term, “robot” implies a machine capable of carrying out a complex series of actions automatically. Robotic surgical systems have not reached this stage of development and are machines designed to interact and assist humans to make surgery safer and more efficient.
 
As of 2020, the application of robotics in spine surgery has been predominantly associated with pedicle screw insertion for spinal fixation [pedicle screws are a fixation technique routinely used in spinal surgery to stabilize vertebrae]. Most studies on robot-assisted spine surgery have investigated lumbar or lumbosacral vertebrae while studies on the use of robotics for placing screws in the cervical and thoracic vertebrae are limited.
 
Robotic systems in spine surgery are commonly used for posterior instrumentation with pedicle screws and rods, which are procedures that require repetitive movements during lengthy operations, as well as delicate manipulation of vital structures in restricted surgical areas. Traditional manual techniques of placing screws are dependent on the experience of the surgeon and can result in breaching the pedicle. Misplaced pedicle screws not only create complications for patients but also can result in a risk of malpractice litigation for surgeons. Safety and precision concerns have fuelled the demand for the use of robotic systems in pedicle screw implantation to increase consistency, reduce inaccuracy, minimize radiation exposure, and decrease operative time. Findings of a research study published in the May 2017 edition of Neurosurgery, reported accuracy of pedicle screw placement using robotic systems as high as ~94% to 98%.
 
The spine market appears to be at an inflection point with an increasing number of companies developing and launching robotic surgical systems. It seems reasonable to suggest therefore that the increased investment in this emerging area is likely to impact the spinal implant and devices market over the next decade.
Two categories of surgical robots

There are two categories of surgical robots used in spine surgery: (i) master-slave systems and (ii) trajectory assistance robots. A prominent, commercially available example of the former is the da Vinci surgical system,  developed by Intuitive Surgical, a Nasdaq traded pioneer in robotic surgery founded in 1995. An example of the latter is the Mazor X Stealth™, which since 2018, has been owned by Medtronic, a giant American MedTech corporation and one of 4 dominant players that control >70% of the global spine market.  

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The da Vinci

The da Vinci robot is a master-slave system and the most popular surgical robot in the world. It is designed to facilitate minimally invasive surgeries and is controlled by a surgeon while seated at ‘master’ console. In 2000, it received FDA-approval for general laparoscopic procedures. Despite costing ~US$2m and having high operating costs, there is an installed base of ~6000 da Vinci units worldwide. The system is used by surgeons in all 50 US states and in ~67 countries. In 2020, >8.5m surgical procedures had been performed using the system. 

In 2014, the da Vinci system first entered the Chinese market and by 2019, 112 robots had been installed and used in >110,000 surgeries. However, China’s high import tax on foreign machinery limits the broader use of da Vinci in the country. Currently, the prevalence of robotic surgery in China is much lower than in some Western countries, as well as Japan and South Korea. However, this is could change when China launches its first surgical robotic system, which is expected to be the Micro Hand S. This is a system based on origami-like panels, and features a foldable, compact design that allows for a wide range of possible movements by the instruments in the limited space of an OR. 
 
A user’s opinion

In the video below, Christopher Anderson, the lead robotic surgeon at St George’s University Hospital, London, describes the da Vinci robot and says, “The term ‘robotics’ is a misnomer because it implies that the instrument has its own intelligence, but it’s not the case”. Surgeons control the “master” system while seated at an ergonomic console viewing high-definition 3D images of the surgical site. The system’s “slave” aspect consists of 3 to 4 interactive arms, which hold surgical tools, and one controlling a camera. With Intuitive’s proprietary “endo wrist” technology, the robotic arms replicate what a surgeon’s arm can do by scaling the surgeon’s hand movements in relation to the robotic arm movements and filtering out tremors. The system’s ergonomic design means greater comfort for the operating surgeon, reducing the problem of fatigue. Patient benefits include smaller incisions, less pain, and faster recovery.
 

Some surgeon-operators of the da Vinci suggest that the lack of haptic feedback and the inability of the surgeon to be stationed at the operating table are limitations of the system. Not according to Anderson, however, “The system is completely and intuitively controlled by the surgeon”, and the “3D vision inside the visor of the console provides a depth perception, which enables the surgeon to know how far to manoeuvre inside the tissues”.

The da Vinci has been used for numerous spine procedures including anterior lumbar interbody fusions (ALIF) [a common spine fusion from the back], resections of thoracolumbar neurofibromas and paraspinal schwannomas [rare usually non-malignant spine tumours]. Compared with traditional open surgery and other robotic systems, more recent versions of the da Vinci provide enhanced visualization and increased magnification of the surgical field, which facilitates careful dissection of fine structures and improved patient outcomes.
 
The Mazor
 
The Mazor is a trajectory assisted surgical system and the first robot to be widely used in both open and minimally invasive spine surgery (MISS) for a variety of clinical indications. The system positions surgical instruments according to a preoperative virtual plan and provides superior intraoperative navigation compared to traditional guidance systems. It is designed to position an effector [a gripper] over a target for a precise stereotactic insertion procedure. In some Mazor systems, the target insertion site and trajectory can be virtually planned on preoperative images, such as X-rays, CT scans and MRIs. Such planning allows surgeons to safely visualize surgical trajectories, avoid critical regions and adjust if necessary. The positioning of surgical instruments mounted at the end of the system’s robotic arm is registered to a preoperative image and automatically adjusted by a control computer, which instructs and directs the robotic arm based on its interpretation of intraoperative imaging.

An early version of the Mazor called the SpineAssist, which was developed by Mazor Robotics, an Israeli company, received FDA approval in 2004 to assist with placement of pedicle screws and since then, it has had several upgrades. In 2016 the company launched the MazorX, which was enhanced by combining proprietary software to plan surgical procedures, a robotic arm to precisely guide the placement of implants during complicated spine surgery, and real-time 3D imaging feedback to ensure procedures proceed as planned. This increased accuracy and improved patient outcomes compared to traditional spine surgery. In 2018, Medtronic acquired Mazor Robotics for US$1.7bn and soon afterwards, launched the Mazor X Stealth™ with even more advanced capabilities. Mazor systems have been installed in ~15 countries and used in >24,000 spine surgeries.
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Other robotic surgical spine systems

In addition to the da Vinci and the Mazor, there are further robotic systems currently used in spine surgery. These include: (i) Zimmer Biomet’s ROSA® Spine, which is like the Mazor and received FDA approval in 2016, (ii) Brainlab’s Cirq®, launched in 2015, (iii) Globus Medical’s ExcelsiusGPS® launched in 2017, (iv) Stryker’s Mako, also launched in 2017, and (v) TINAVI Spine’s TiRobot®, launched in 2016.
Syed Aftab (pictured above), consultant spinal surgeon and robotic surgical lead at the Royal London Hospital, Barts Health NHS Trust, a major London teaching hospital, uses Brainlab’s Cirq®, a trajectory assistance system in combination with a 3D C-arm. “We were the first surgical unit in the UK to have a robotic spinal system and the first to perform robotic spinal surgery”, says Aftab, who teaches spine and orthopaedic surgery at London’s Queen Mary University, and is also the spinal surgery lead at Complex Spine London. He adds “We chose Brainlab’s Cirq® because it has a small footprint, it’s lightweight, easy to transport from one OR to another and is also cost effective compared to other systems”.

According to Aftab, Brainlab’s second generation system is a significant improvement on its first, “it has a true automatic feature, which finds and holds my screw trajectories based on my preoperative plan. I primarily use the system for pedicle screw insertion. It has applications in the lumbar spine but has significant advantages in the upper cervical spine where the surrounding at risk structures are more challenging and the bony anatomy is less forgiving. The combination of navigation and robotics substantially increases accuracy, reduces the time of surgery, and frequently takes away the need for large dissections to create visual exposure of the operating field. Also, I’ve found the robotic system extremely useful where anatomical localisation is difficult due to previous surgery or altered anatomy, such as in degeneration or ankylosing spondylitis [a form of arthritis in which the spine becomes inflamed and fused]”.

Aftab and his colleagues have found the outcomes of their robotic surgeries “very positive” from both patient and health professional perspectives. “Robotic surgical systems definitely add value to pedicle screw placements compared to traditional open or minimally invasive spine surgery. However, it seems important to point out that it is not altogether clear whether the benefits are derived from the robotic system or from the embedded advanced navigation”, says Aftab.

According to a study published in the February 2017 edition of Neurosurgery, the ExelsiusGPS®, “has the potential to revolutionize the field of robotic-assisted spinal surgery. With automated accuracy, reproducible outcomes, efficient integration, automatic patient registration, constrained motion for safety and automatic compensation for patient movement”. The system is like the Mazor and ROSA® Spine but appears to address many of the drawbacks of previous robotic-assisted systems. In November 2019 DePuy Synthes announced a joint venture with TIVANI, to market the TiRobot® for spine surgery in China.

In May 2021 South Korean MedTech company Curexo  received FDA approval for its Cuvis-spine robot, which guides pedicle screw insertion and uses a robotic arm to make surgery safer and more efficient. The company expects to market Cuvis in Europe and the US. NuVasive, a US MedTech company, expects its robotic platform, Pulse, to receive FDA approval in summer 2021 for all spinal surgeries, not just complex or low-acuity cases. When launched, it will combine neuromonitoring, surgical planning, rod bending, radiation reduction, imaging, and navigation functions and is expected to compete with other robotic spine offerings on the market, including Medtronic's Mazor X, Globus Medical's ExcelsiusGPS® and Zimmer Biomet's Rosa Spine®.
 
Headwinds
 
Compared to traditional fluoroscopic-assisted freehand approaches to pedicle screw placement and other spinal procedures, robotic systems may be more accurate, more efficient, and safer. However, it is worth mentioning that there is a range of robots being used in spine procedures and they do not all guarantee the same accuracy and precision. Errors arise because of their complexity relative to fluoroscopically guided surgery and some existing user interface software can be cumbersome and unintuitive, which suggests that there is a steep learning curve for health professionals wishing to introduce robotic surgical systems into their practice. Studies show that the accuracy of pedicle screw placement increases, and operating time decreases with the number of robotic surgical procedures performed by a clinical team. Thus, there is a learning curve and training is critical; not only for surgeons, but also for other health professionals in the OR.
 
It is generally accepted that the cost of training and the time it takes could slow the further adoption of robots in spine surgery. Surgical education is just beginning to include robotics as part of standard training for surgeons. However, there are several different robotic systems in clinics and learning curves can vary according to the version of the robotic system used, so standardization of surgical training becomes a challenge, and surgical expertise plays a significant role in obtaining a fair comparison between robotic-assisted and traditional surgery.
 
Added to the increased training burden associated with robotic techniques are of the high costs of systems. To reduce the financial burden on hospitals, some producers provide innovative financing terms and bundle a robotic system with a range of implants and other devices and services. These issues together with current patchiness of evidence on the efficacy of robotic surgical spine systems are barriers to t the widespread utilization and development of surgical robots. 
 
Tailwinds: China and robotic surgical systems
 
Over the past two decades Western corporations have dominated the robotic surgical spine market. US, UK, and EU have differed in their approaches to the development and adoption of robotic surgical systems. The US has tended to focus on technical challenges such as tactile sensing and navigating confined spaces, while the UK has been more market driven and focused on the cost effectiveness and regulatory standards of systems. The EU, on the other hand, has attempted to address both R&D and translational issues by promoting academic and industrial collaborations. In recent years, Chinese initiatives, which are more closely aligned with the EU approach, have been gaining momentum and are positioned to impact the spine market in the next decade.
 
China is challenged by its vast and rapidly ageing population and a shortage of surgical expertise. By 2050 China’s senior citizen population (those ≥60) is projected to grow to >30% of the total population, up from ~12% today, and this is expected to substantially increase the percentage of its retirees relative to workers, which will significantly increase the burden on its healthcare providers. 
 
Beijing believes these challenges can be helped by robotic surgical systems. In addition to acquiring >100 da Vinci systems, China has made the production of domestic robotic surgical systems part of its 2006 15-year plan for science and technology. In 2011 the Chinese government reaffirmed this commitment by including the increased use of robotics in healthcare in its 12th 5-year plan, and over the past decade, Beijing has made substantial R&D investments in the development of robotic surgical systems.
 
In 2019, China opened the Medical Robotics Institute in Shanghai Jiao Tong University, which is the nation’s first academic establishment dedicated to the study of medical robotics, and appointed Guang-Zhong Yang as its founding dean. Professor Yang formerly was the founding director of the Hamlyn Centre for Robotic Surgery at Imperial College London. According to Yang, medical robotics have been growing in China for the past two decades driven by, “The clinical utilization of robotics; increased funding levels driven by national planning needs; and advances in engineering in areas such as precision mechatronics, medical imaging, artificial intelligence and new materials for making robots”.
 
China’s robotic surgical industry started later than its foreign peers, but the nation now has ~100 medical robot companies. The Chinese sector is in a transitional phase from R&D and clinical trials to commercialization and mass production. The nation’s medical robot market is expected to be worth ~US$2.5bn by 2026. China’s growing interests in surgical robotic systems is expected to significantly increase competition and accelerate technological developments.
  
Tinavi Medical Technologies
 
A notable example of a Chinese enterprise specialising in surgical robotic systems is Tinavi Medical Technologies, a Beijing-based company, backed by China’s Ministry of Science, the Beijing Government, and the Chinese Academy of Science and listed on China’s National Equities Exchange Quotation [an over-the-counter system for trading the shares of a public limited company]. In 2016, Tinavi received fast-tracked approval from the central government to sell the TiRobot®, the first robot-assisted surgical product made in China. As of December 2020, the system had assisted in 10,000 surgical procedures. With its unique algorithm for calculating pedicle screw trajectories, the TiRobot® can precisely move to a planned position and provide surgeons accurate and stable trajectories for implants and pedicle screws; it is expected to make high volume spine surgeries more accurate and standardize less common and more complex spine surgeries. Research published in the January 2021 edition of the Journal of Orthopaedic Surgery and Research, suggests that, “iRobot-assisted vertebroplasty can reduce surgery-related trauma, post-operative complications, and patients’ and operators’ exposure to radiation”. 
 
University-industry-research ecosystem

The production of surgical robotic systems in China is advantaged by the nation’s deep and functional university-industry-research cooperation. It is relatively common in China for technology companies to have strategic alliances with university research institutes with years of accumulated technical expertise. With respect to robotic surgical systems that require application of medical theories and technologies, mechanical engineering, robotics, optics, computer science and AI, such joint ventures bring together interdisciplinary teams with years of multidisciplinary research experience in bio-machine interfaces, integrating bionic techniques, and investigating new materials technologies.

An example of such an interdisciplinary joint venture is a project focussed on making robotic surgery systems more capable of replicating the tactile feel and sensation a surgeon experiences during more invasive traditional procedures. The project is led by researchers at the 3rd Xiangya Hospital of Central South University, in collaboration with Tianjin and Beihang Universities.
 
Based on their combined experiences of minimally invasive surgery, researchers have built and analysed classified databases on the physical characteristics of patients, on the interaction between human soft tissues and surgical instruments, and on operator-instrument interfaces. This combined knowledge has been used to optimize the design of surgical robotic systems to make them more effective, more intuitive, and safer than exiting robots.
 
The project team is planning for a multi-centred, prospective, randomised trial to collect more data associated with the system’s safety and effectiveness, which is expected to accelerate the manufacture of their surgical robot. Further, the project team leaders at the 3rd Xiangya Hospital, plan to build a national training institute to educate surgeons in the use of the system, and this is expected to contribute to the robot’s broader use. There are also plans to establish a clinical information centre, by collecting data on the use of the system, and employ AI and machine learning algorithms to analyse them. This is expected to optimize performance, inform upgrades, and make the robot globally competitive.
 
The “interpretability challenge”

Currently, robotic surgical systems neither make cognitive decisions nor execute autonomous tasks but assist clinicians to enhance pre-operative planning, improve intra-operative guidance, provide superior interpretations of complex in vivo environments, and increases the accuracy, safety, and efficiency of surgical procedures. It seems reasonable to suggest that robotic surgical systems will become more autonomous as they increase their AI and machine learning capabilities, which facilitate instantaneous assessment of complex surgical settings that trigger immediate therapeutic actions, that the surgeon using the robot might not fully understand. This situation can be further complicated by the complexity of algorithms that depend on neural networks comprised of thousands of artificial neurons. This further blurs the reasoning behind specific interpretations and consequent actions of robotic systems. In many such cases the developers of machine learning algorithms cannot explain why an AI driven system arrived at a specific interpretation or a suggested action.
 
This failure to understand is referred to as an “interpretability challenge”, or more commonly, the “black-box” problem; a concept not broached in surgical studies but discussed in medical ethics.
 
Reactions from market stakeholders to such a challenge are likely to be mixed. For example, some healthcare providers might welcome more autonomous robotic surgical systems to compensate for shortages of experienced surgeons, others might perceive autonomous robots as having the potential to “level the playing field” among surgeons and contribute to a generally accepted level of surgical services across diverse regions, while other providers might be against surgeons abdicating responsibility to a robot. Whatever the reaction of providers, as robotic surgical systems advance, they are likely to become more complex and less interpretable by the surgeons using them. Increasingly, stakeholders will be required to “place their trust in the system”. Gaining this trust from surgeons, patients and providers could be a more significant obstacle to the further adoption of robotic surgical systems than the obstacles commonly referenced such as costs, scarcity of resources, lack of training, and inconclusive clinical studies.
 
To counter the “black box” syndrome is “explainable AI” (EAI), an AI solution designed to explain its intent, reasoning and decision-making processes in a manner that can be understood by humans. Until EAI becomes an integral part of robotic surgical systems it seems reasonable to assume that such could face some difficulties progressing beyond their assisted surgical status.
 
Takeaways
 
Currently, robotic spine surgery is in its infancy and most of the objective evidence available regarding its benefits draws from the use of robots in a shared-control model to assist with accurately placing of pedicle screws with minimal tissue damage. The performance to-date of robotic surgical systems suggest a new era for spine surgery by their capacity to refine surgical dexterity and augment human capabilities. The current limitations of surgical robots are likely to provide incentives for innovation, which holds out the prospect of developing more advanced robots that further enhance spine surgery outcomes while reducing costs. This is likely to provide a significant boost to well-resourced spine companies developing robotic systems and put pressure on others to change their business models dominated by incremental fixes to their existing product offerings. But keep an eye on Chinese endeavours in robotic surgical systems and the responses to the interpretability challenge in different regions of the world.

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