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.
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