What is robotic surgery?
Medical robotics has been in use for approximately 30 years. Robotic surgery is called “revolutionary” by many surgeons who value it for its many advantages, both real and potential. Its origin owes much to the weaknesses of the minimally invasive surgery (MIS) technologies that preceded it.
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Today, gall bladders are routinely removed by a surgeon on one continent from a patient on another, using robotic telesurgery. Voice-activation of robotic arms and haptic feedback offers surgeons the command they seek over the surgical procedure itself.
Issues with minimally invasive surgery
Minimally invasive surgery is limited by the loss of touch- and force-related sensations, which are so crucial in determining the accuracy of surgical operations.
Dexterity of movement is limited by the natural limitation of the instrument, which has only four degrees of motion unlike the human wrists and hand, which have seven. Physiological tremors are also rapidly carried into the operating field by the rigid laparoscopic instrument.
All these factors drove the development of surgical robots, beginning with the Puma 560 in 1985, a robot that carried out neurosurgical biopsies, and a little later, the transurethral resection of the prostate.
As telesurgery became an area of intensive research at the National Air and Space Administration (NASA) Ames Research Center, surgical robotics began to advance dramatically.
First to appear were camera holders and positioners, such as the Automated Endoscopic System for Optimal Positioning (AESOP), a voice-controlled camera holder, in 1990.
Next came the active medical robots, such as the da Vinci system (Intuitive Surgical Inc.), an advanced master-slave system, with multiple robotic arms or manipulators controlled remotely by a surgeon from a console. These systems use miniaturized operating arms, unlike the one-centimeter surgical arms of the Puma 560, avoiding the need to retract the sides of the incision. The Endo-Wrist features of the operating arms also provide seven degrees of freedom. Newer systems use ergonomically superior open consoles rather than the closed one of the da Vinci.
Traditional systems like the da Vinci pivot about the insertion trocar, which both limits dexterous management of the instruments and may cause inadvertent damage to adjacent vital structures. The large size and cost of these systems is prohibitive in most instances to the routine adoption of robotic surgery.
Laparo-endoscopic single-site surgery (LESS) robots insert the camera and multiple instruments through a single incision, preferably the umbilical, in which case there is no scar. Smaller systems such as the SurgiBot-SPIDER (Single-Port Instrument Delivery Extended Research) system allows robotic surgery at a significantly lesser cost, but have not yet gained FDA approval.
Newer robots are constructed of soft, flexible and deformable materials. The use of biocompatible soft materials, superelastic materials and 3D-printed soft plastics such as silicon elastomers, allow for greater safety. These allow changes in robotic shape and mechanical properties in response to touch, thus enhancing their greater intrinsic safety. Newer robots also allow elongation to tune the exact position of the robot, and greater flexibility of the instrument neck.
Tissue property modeling offers haptic feedback. Bendability and stiffness controllability are key aspects of the newer robotic surgical systems emerging today. Newer flexible robots sense the force applied by shape reconstruction, with the stiffness of the advancing tip being controlled by the tension. This allows active adjustment of the payload.
The ability to achieve variable stiffness in different segments of an endoscope could allow the robot to move flexibly within the lumen of a soft organ, but not recurve on itself when required to negotiate a sharp turn, for instance. With these advances, cheaper and safer robots can be designed for each patient and each procedure, making them non-invasive and more cost-effective.
Everting pneumatic tubes were used to generate robots that can elongate to hundreds of times their original length, can maneuver through tight spaces and move around corners or blocks. These biomimetic robots are modeled on plants, and can be used for remote manipulation.
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Some interesting robotic surgical systems in use
Newer colonoscopic surgical robots demonstrate improvements in four crucial areas: adjustable stiffness, detectability, bendability, and controllability. A miniature robotic system (“Endotics”) with inchworm-like vacuum-based mobility has been described, to enhance the accuracy of colonoscopic diagnosis and surgery.
Similarly, a novel constrained tendon-driven serpentine mechanism (CTSM) has been designed to overcome these obstacles, with expanded workspace, and better control of the bending section.
The NeoGuide colonoscopy system is an advanced soft robot that incorporates compliance, safe interaction with the body, actuation and sensing, greater dexterity and increased workspace.
This uses a computer-assisted insertion tube with complete articulation, rather like a snake, where the tip of the scope sets the direction for each successive segment, thus allowing the tube to take different shapes at different depths of insertion. It also has variable stiffness control, preventing incomplete or painful endoscopy.
The Minimally Invasive Neurosurgical Intracranial Robot (MINIR) is another newer robot used to remove brain tumors, based on a CTSM with SMA actuators. The Flex system uses cables with variable tension to modulate the flexibility of the endoscope, allowing several procedures to be carried out while using only a fraction of the space required by the da Vinci system.
The Meshworm design simulates earthworm movement, and is meant for colonoscopy, as is the Invendoscope. The STIFF-FLOP soft robot is based on the octopus arm, using fluidic chambers with a modular approach to stiffening and bending.
The Aer-O-Scope is an Israeli self-propelling colonoscope that uses carbon dioxide to push itself through the colon up to the cecum, without the need for external pushing.
Remote endoscopic operation under MRI‐based guidance allows excellent detectability of the scope, provided electromagnetic fields are eliminated.
Other surgical modalities using robots
Noninvasive robots are useful in imaged-guided therapy, including the CyberKnife or image-guided radiosurgery, the first such platform to be FDA-approved. The use of non-invasive thermotherapy using high-intensity focused ultrasound (HIFU) coupled with robotic manipulators has been described.
Newer Approaches
NOTES
Such advancements also bring natural orifice transluminal endoscopic surgery (NOTES) nearer, where surgery can be truly non-invasive, by helping to achieve greater stability of the instruments despite their flexibility, allow sufficient force to be applied for traction and large organ retraction, proper positioning of the instruments, greater dexterity and imaging quality.
Miniature in vivo robots
Miniature in vivo robots, developed by Virtual Incision and Center for Advanced Surgical Technology (CAST), are a novel approach with the whole MIS surgical platform being inserted into the peritoneal cavity. These have two arms with multiple functionalities, with several joints for unlimited flexibility.
With a minute entry incision, miniature motors driving the arms, and a high degree of flexibility, these offer scarless surgery, and can be used by inexperienced surgeons under the mentorship of veterans, highly expanding patient access.
These robots allow surgeons to image the surgical site from many angles, and to complete the surgical task on-site or remotely. These are inexpensive, and easily transportable, allowing MIS to be done anytime, anywhere, by almost anyone, from outer space to battlefields or remote medical emergency situations.
Capsule robots
These are miniaturized endoscopes that can be used in many diagnostic tests, surgeries or for drug delivery. They can be manipulated via magnetic interactions, allowing for an untethered design with enormous freedom of movement, and are extremely small, causing less tissue damage and fast accessibility.
Microbots
Microbots, though far in the future, are a potential advancement which do not require any incision at all, but could be introduced into the circulation and transported to a specific destination.
Conclusion
Microrobots are very different from the earlier master-slave systems, without physical connection to the operator, with much greater access, and with the potential for contained propulsion, consistent imaging, accuracy of telemanipulation and miniaturized functionality. When these issues are addressed, microrobots could revolutionize surgery.
References
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Lanfranco, A. R. et al. (2004). Robotic surgery: a current perspective. Annals of Surgery. https://dx.doi.org/10.1097%2F01.sla.0000103020.19595.7d. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1356187/
Warren, H. et al. (2017). The future of robotics. Investigative and Clinical Urology. https://dx.doi.org/10.4111/icu.2017.58.5.297. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5577324/
Eickhoff, A. et al. (2006). Computer-assisted colonoscopy (the NeoGuide Endoscopy System): results of the first human clinical trial ("PACE study"). American Journal of Gastroenterology. doi: 10.1111/j.1572-0241.2006.01002.x. https://pubmed.ncbi.nlm.nih.gov/17156149/
Khandalavala, K. et al. (2020). Emerging surgical robotic technology: a progression toward microbots. Annals of Laparoscopic and Endoscopic Surgery. https://ales.amegroups.com/article/view/5499/html
Further Reading