In the realm of medical science, robotic assistance systems have reached a state of technological maturity and widespread availability. These systems are now playing an increasingly pivotal role in patient care. This review provides an overview of the fundamental principles of robotically assisted surgical systems, touching on the historical and current developments in the surgical robotics landscape, as well as the prevailing areas of focus in contemporary research. While a comprehensive treatment of this subject matter is not possible within the confines of this format, we offer references for further exploration and more exhaustive reviews on specific aspects. Thus, this work serves as an introductory guide, tailored especially for newcomers to this field, encompassing investigators, researchers, medical device manufacturers, and clinicians.

Recent Findings
Current research in Robotically Assisted Surgical Systems (RASS) predominantly leverages established robotic platforms. The ongoing drive in this domain aims to minimize patient trauma while maximizing surgeon dexterity. This is being achieved through the development of miniaturized instruments and semi-autonomous assistance functions. Furthermore, there is an emphasis on providing surgeons with essential information through novel imaging sensors, techniques for multimodal sensory feedback, and augmented reality. The emerging field of Surgical Data Science utilizes data management and processing methods, including machine learning on medical data, to deliver optimal, individualized, and context-aware support to the surgeon.

Summary
Robotic systems are poised to profoundly influence the landscape of patient care in the future. However, their development is contingent on meeting myriad medical, technical, regulatory, and economic prerequisites. Therefore, the progress in this domain necessitates a close, dynamic, and interdisciplinary collaboration between stakeholders from healthcare institutions, industry, and scientific research.

Introduction
From the conceptual ideas that emerged in the 1970s to the present day, over 7 million procedures have been performed using Robotically Assisted Surgical Systems (RASS). The Medical Robotics Database (MeRoDa), maintained by the university clinics Mannheim and Heidelberg in Germany until 2010, documented over 450 medical robotics projects worldwide. However, only a few of these research projects led to commercially available systems, mainly due to technological complexity, patent challenges, and regulatory obstacles, coupled with a lack of standardization, making the development of such systems high-risk and costly. Furthermore, clinical relevance and cost-effectiveness must be considered from the outset of development. Only by doing so can a RASS evolve into a commercially successful product, enhancing medical care for a broader patient population.
Primarily, RASS aims to alleviate the burdens faced by clinicians. For example, robot arms designed to position and hold instruments relieve surgical assistants from constant holding tasks, allowing them to contribute to other valuable aspects of surgery. User-friendly system designs enhance ergonomics and instrument handling, thus improving surgical precision and cognitive load. Beyond enhancing a surgeon’s overall work quality, RASS can enable less invasive procedures, given their highly dexterous instrumentation, enabling smaller and less traumatic access to the patient’s body. From a clinical perspective, RASS have the potential to enhance safety for both clinicians and patients, standardize the quality of therapy, irrespective of the surgeon’s experience, and reduce hospitalization time, ultimately lowering costs while improving patient outcomes.
Despite the challenges in developing and introducing RASS into the market, over 40 systems are commercially available for various surgical applications, with a similar number in development.
This paper proceeds to provide an overview of historical developments in “Historical Overview,” introduces definitions and standards for robot-assisted surgery in “Definitions and Standards,” discusses commercially available RASS in various surgical domains in “Commercially Available RASS,” and describes contemporary research trends in RASS in “Current Research Trends in RASS.”

Historical Overview
In the 1970s, NASA explored the potential use of telemanipulation in robotic assistance systems for emergency medicine, laying the conceptual groundwork for modern robot-assisted laparoscopy. Around the same time, the development of the ROBODOC® system, which was designed for bone milling during hip endoprosthesis implantation, commenced at IBM’s T.J. Watson Center and U.C. Davis. The first clinical study for ROBODOC® was conducted in 1992, and it gained CE certification for the European market in 1996. This system is currently marketed by THINK Surgical Inc. Since 2014. In 1992, the development of the Acrobot system began at the Imperial College London, marking the inception of robotic assistance in knee arthroplasty. The Mako system, now sold by Stryker Corp. Medical, has its foundation in Acrobot’s technology.
In the field of minimally invasive surgery, the concept advanced, with research institutes enhancing the NASA concept from the mid-1980s onward. The U.S. military recognized the potential benefits of robotic technology for remote-controlled first aid for wounded soldiers and actively promoted corresponding research. Computer Motion Inc. and Intuitive Surgical Inc. were established in 1989 and 1995, respectively, and they continued NASA and SRI’s (Stanford Research Institution) research for commercial exploitation. In 1993, Computer Motion’s AESOP arm, designed for positioning an endoscopic camera, received FDA approval. In 2001, Computer Motion introduced the ZEUS system for minimally invasive surgery. The FDA had approved Intuitive Surgical’s da Vinci system a year before. Following the merger of Intuitive Surgical and Computer Motion in 2003, AESOP and ZEUS were discontinued and removed from the market.
Germany’s Forschungszentrum Karlsruhe developed ARTEMIS, one of the world’s first demonstrators for minimally invasive robotic surgery in the early 1990s. In 1996, a laparoscopic cholecystectomy was successfully performed on a pig using a prototype of this teleoperation system for general and heart surgery. However, the technology did not make it to market.

Definitions and Standards
The lack of standards and definitions in surgical robotics has created challenges in transforming research prototypes into approved medical devices. To streamline these processes while ensuring the fundamental safety and performance of RASS, the standardization organizations ISO and IEC published IEC/CD 80601-2-77 for surgical robots. ISO 8373:2012 (Robots and Robotic Devices – Vocabulary) defines robots as “[…] actuated mechanisms programmable in two or more axes with a degree of autonomy, moving within their environment to perform intended tasks.”

Definitions
– Robotically Assisted Surgical Equipment/System (RASE/RASS): A “Medical Electrical Equipment/System that incorporates Programmable Electrical Medical System actuated mechanisms intended to facilitate the placement or manipulation of Robotic Surgical Instrument.”
– Robotic Surgical Instrument (RSI): An “Invasive device with an applied part, intended to be manipulated by RASE or RASS to perform tasks in surgery.”

Commercially Available RASS
Various subsections describe RASS in different surgical domains, either already commercially available or soon to be launched. The primary focus is on systems from North America and Europe, regions with established systems and well-documented platforms.

Laparoscopy
Conventional laparoscopic surgery offers numerous patient benefits, such as reduced trauma and shorter recovery times. However, it presents significant ergonomic challenges for surgeons due to instrument handling and ergonomics. RASS for laparoscopic surgery aim to address these challenges. These systems typically involve robotic arms to hold the endoscope and instruments, granting surgeons telemanipulation of these instruments in all six degrees of freedom. The da Vinci system by Intuitive Surgical is one of the most common RASS for laparoscopy. The latest generation, the da Vinci Xi System, is commercially available, featuring a closed console concept and mounting all robot arms on a common boom.
Other RASS, such as the Senhance Surgical System from TransEnterix Surgical Inc., the Versius Surgical Robotic System from CMR Surgical Ltd., the Dexter robot from Distalmotion SA, and the avatera System from Germany, offer alternative designs and unique features in laparoscopic surgery.

Spine and Neurosurgery
In neurosurgery and spine surgery, RASS have applications like biopsies, deep brain stimulation electrode placement, and vertebral fixation. These robotic systems serve as guides or bearing devices for the high-precision insertion of surgical instruments, helping maintain accuracy. Optical or electromagnetic navigation and tracking systems are used for intra-operative registration, aligning the robot with the patient and pre-operative imaging data. Examples of commercially available systems include the Mazor X Stealth Edition System, ROSA ONE Spine/Brain System, ExcelsiusGPS System, and the neuromate System, among others. These systems use different architectures and technologies to achieve their objectives.

Orthopedic Surgery
In orthopedic surgery, RASS are employed for joint reconstruction with knee and hip endoprostheses. The systems use preoperative image data and intraoperative registration to guide surgeons. The systems support the surgeon in different ways, from manual guidance with assistance to automated milling. Examples include the Mako System, the Navio Surgical System, the ROSA Knee System, and the TSolution One System, each offering unique approaches to support the surgeon.

Vascular Surgery
In heart and vascular surgery, telemanipulated RASS are available for angioplasty procedures. These systems allow for remote control of catheters and other instruments, enhancing precision, reducing radiation exposure, and improving working conditions for physicians. The R-One system from Robocath Inc. and the CorPath GRX system are two notable examples, each designed for specific vascular interventions.

RASS for Other Disciplines
RASS is also available or under development for various diagnostic or interventional applications, including microsurgery, ophthalmology, otorhinolaryngology, radiation therapy, and endoluminal endoscopic procedures like bronchoscopy. For instance, Carl Zeiss Meditec offers the KINEVO 900 robotic visualization system for neuro- and spinal surgery. KUKA, a robotics company, adapts its robot systems for medical applications. The KUKA LBR Med, a medically certified robotic arm, is now a core component of many RASS from international companies.

Current Research Trends in RASS
Research in RASS is dynamic and diverse, with various focus areas shaping the field. These trends include improving system autonomy, enhancing imaging and sensory feedback, and applying data science to medical data. Some research areas seek to enhance the surgeon’s capabilities while others aim to reduce trauma and improve surgical outcomes. Collaboration among stakeholders from hospitals, industry, and science is vital to foster further research and development in RASS.
One prominent trend in the field of robotic-assisted surgical systems (RASS) involves the utilization of established robotic platforms such as the da Vinci Research Kit, RAVENTM, and the KUKA LBR Med. The da Vinci Research Kit, designed as an open-source research platform, is rooted in the first generation of the da Vinci system. It was originally developed at Johns Hopkins University and is currently in use at over thirty universities and research institutions across ten countries. The entire system’s architecture and software details are well-documented. The RAVENTM, initially developed at the University of Washington, is a research platform specialized for telesurgery in robot-assisted laparoscopy and is now distributed by Applied Dexterity Inc. The KUKA LBR Med, as previously discussed in the “RASS for other Disciplines” section, is an adaptation of the collaborative industrial lightweight robot KUKA LBR iiwa, tailored for medical applications. Both the KUKA LBR Med and the LBR iiwa rely on the lightweight robot technology developed at the Institute of Robotics and Mechatronics of the German Aerospace Center (DLR). Although these platforms may provide less freedom in terms of hardware design and control architecture when compared to self-developed systems like the Hamlyn Arm or the DLR MiroSurge, they offer the advantage of well-tested hardware and software, broad availability, and simplified collaboration with partners utilizing the same system. Furthermore, they facilitate the transition from research to a commercially viable product.

Another significant focus in RASS research is the quest for high dexterity while minimizing trauma to the patient. This challenge is instrumental in guiding research in various areas:
1. Design of Miniaturized Robotic Instruments: These instruments must be small in diameter to reduce patient injury, possess the necessary stiffness to enable adequate manipulation force, and offer sufficient motion capabilities for reaching the surgical site and performing tasks. The development of numerous joint mechanisms and the increasing popularity of continuum robots, particularly for applications necessitating small instrument diameters and low manipulation forces, are evidence of the ongoing research in this area.
2. Less Invasive Surgical Techniques: Minimizing patient trauma remains a primary objective of surgical robotics research. This has led to the creation of numerous robotic systems for minimally invasive surgery, such as laparoscopy. Alternative techniques like Natural Orifice Transluminal Endoscopic Surgery (NOTES) and endoluminal interventions aim to further reduce patient trauma. NOTES involves performing surgical procedures through the body’s natural orifices, while endoluminal interventions occur entirely within a hollow organ. Certain robotic systems developed for endoluminal interventions, like the Flex® system by Medrobotics and the Monarch® Platform by Auris Health Inc., have received FDA approval. These innovations mark important developments in reducing patient trauma during surgeries.
3. Semi-Autonomous Assistance Functions: Some RASS are designed to provide haptic guidance to the surgeon, offering assistance with resection lines and preventing unintended injury to sensitive structures through active constraints or virtual fixtures. Additionally, instrument mechanisms can be integrated into the robotic system to automate specific sub-tasks, such as commercially available staplers, clip applicators, or suturing instruments.

Ensuring that surgeons have access to adequate information during robotic-assisted surgery is another pivotal research direction:
1. Multimodal Sensory Feedback: Commercially available systems for robot-assisted laparoscopy and vascular surgery still face challenges in achieving transparent telepresence, particularly the lack of haptic and tactile feedback. The development of cost-effective, sterilizable, or disposable miniaturized sensors for integration into robotic instruments remains a technological challenge. However, recent advances have been made in force-sensing laparoscopic instruments and trocars, which are essential for tactile feedback in surgery.
2. Novel Imaging Sensors and Augmented Reality: The intraoperative application of novel imaging sensors, including multi- or hyperspectral, ultrasound, or photoacoustic imaging, coupled with rapid advancements in machine learning, is driving research in advanced imaging methods to enhance the information available during surgery. Augmented- and mixed-reality solutions are being explored to present relevant information to the surgeon by combining preoperative data with real-time surgical site information.

Surgical Data Science is a growing field that deals with collecting, organizing, analyzing, and modeling medical data. The integration of all technical systems in the operating room, including surgical robotic systems, into a common communication infrastructure is an emerging trend. However, several challenges need to be addressed:
1. Communication Standards for the Operating Room: The adoption of open standards and norms is crucial for achieving seamless data exchange in the surgical robotic domain. Currently, many medical device manufacturers use proprietary communication standards, which complicate data exchange across different systems.
2. Quality Standards for Medical Data: Varying skill levels of healthcare providers, diverse medical practices, and differing experiences make data challenging to compare. Ensuring the quality, privacy, and security of patient data is paramount.
3. Modeling of Surgical Procedures: Developing standardized digital models for surgical procedures is necessary for increasing the autonomy of robotic systems and context-aware assistance. It requires a machine-readable representation of surgical knowledge that is currently often only implicit.

In conclusion, the future of surgery will be significantly shaped by the continued integration of RASS. Close interdisciplinary collaboration among scientists, medical device developers, and clinicians is essential for developing and refining these systems. The successful development of RASS necessitates mutual understanding and cooperation between these disciplines, as well as their inclusion in the education of future surgeons to manage the evolving landscape of the operating room. Active collaboration between surgeons and engineers is key to unlocking the full potential of RASS for patient care and improving the overall patient experience.