a freelance medical writer in Mamaroneck, NY.
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For some, the idea of robotics calls to mind autonomous artificial creatures capable of performing tasks at least as well, if not better, than a human. At this time, robots remain tools that are controlled by humans. Although robotic surgery has been developed in partnership with the National Aeronautics and Space Administration with a future goal of allowing surgery for astronauts, it is not yet possible to do so, nor is it yet possible to use robotics to perform surgery in a battlefield or other remote location on earth. Attempts have been made to perform transatlantic surgery, but bandwidth is a problem, as is the expense. According to Ashutosh K. Tewari, Ronald P. Lynch Associate Professor of Urologic-Oncology, Associate Professor of Urology and Public Health, Weill-Cornell Medical College, New York, NY, it could cost around half a million dollars for a 30-min procedure.
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Helping “Hands”
Gloria J. Wiens is Associate Professor, Department of Mechanical and Aerospace Engineering, and Principal Investigator and Director, Space, Automation, and Manufacturing Mechanisms (SAMM) Laboratory at the University of Florida, Gainesville. Her research focuses on the mechanisms side of robotics, where her work addresses the mechanical device (mechanism) design aspects as well as the dynamics and controls. Applications of her group's work include devices that may be used to manipulate cells and tissues and mechanical devices, such as a middle ear prosthetic that can be adjusted in situ without the need of repeat surgery. The middle ear consists of the tympanic membrane (eardrum) and three small bones, the malleus (hammer), the incus (anvil), and the stapes (stirrup). A middle ear prosthetic would replace the small bones when they do not function or did not form properly during development.
Currently, surgeons cannot tell how well a patient will hear after middle ear surgery, so being able to adjust the prosthetic after surgery in an awake patient without a repeat surgery is a clear advantage. “We're looking at adjustability in devices to control them without wires in the patient,” says Wiens. Each patient heals differently, and scar tissue forms differently, she notes. In addition, the materials used have to be biocompatible so the body won't reject them. Surface geometry and other characteristics are important and should not promote the growth of bacteria. Ease-of-use is another important criterion. How the device is actuated is important, so it won't be actuated accidentally, for example, when a patient goes through airport screening or undergoes diagnostic imaging. Inadvertent actuation not only could cause pain by changing the length of the prosthesis, but could affect hearing.
Wiens's group also has a patent pending on an optical force transducer that would extend the dynamic range of microelectromechanical systems (MEMS) force transducers. These dynamic fixturing devices could be mounted on a mesoscale tool and used to manipulate cells and could be scaled to work with tissues. Such a device could be used not only to forces needed to remove cancer cells adhered to other tissues and to aid in designing better techniques to remove cells or to prevent them from adhering at distant sites. In general, Wiens says, she looks at things to advance technology, and the application steers her thought processes, so that a MEMS device designed to manipulate cells and tissues could also be used as an enabler to advance technology in other areas, such as manufacturing on a micro (MEMS), meso, or larger scale. Many of these devices are configured as parallel robots, much like having two arms, one that can control or hold an object, such as tissue, and the other that can perform some measurement or manipulation.
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Able Assistance
Tewari uses robotics to assist him in performing surgery for prostate cancer. He estimates that 40,000–50,000 prostatectomies in the U.S. per year are robotic-assisted. The technology is useful for visualizing structures, such as distinguishing tumor tissue from nerves, and for working in small areas. Currently, about 200–300 robotic surgeries are performed annually at Cornell. Ideally, robotics allows smaller incisions, which results in shorter hospital stays, and leads to significantly less blood loss and transfusions, although operative times are about the same as for open surgery. Tewari notes that “we can clearly see neurovascular bundles with robotics. There are multiple neurovascular bundles, not just one nerve on each side [of the prostate]. We are seeing more with robotics and can see things from better angles with the robot than with open surgery.” He acknowledges that there are good surgeons doing open surgery who will likely continue to do so, and it may be difficult for some surgeons to switch. He notes advantages of robotics are that the instruments can twist and turn much more than laparoscopic instruments; laparoscopic instruments have inner and outer pitch and yaw and can rotate, but with less degrees of freedom than robotics. One person can control three to four instruments using foot and hand controls.
Robotic surgical machines can cost around $1.2–$1.6 million each. In addition, the learning curve is steep, and it may take performing 250 or more procedures for a surgeon to feel comfortable, and for some surgeons, performing up to 500 procedures to be able to preserve function in the patient. In order to determine if survival in patients with prostate cancer is better after robotic surgery than open surgery, it may be necessary to look at 10-year survival rates, although prostate-specific antigen (PSA) levels and tumor-free margin rates might be used as surrogate markers. There have not been any randomized studies comparing robotic to open surgery. According to Tewari, this is because patients have biases and don't want to be randomized. One way to analyze the data would be by using what he calls “poor man's randomization,” a covariate adjustment retrospective analysis. However, there is bias in treatment selection, and the requirements for eligibility for robotic surgery are not necessarily the same for open surgery or other treatment modalities.
In addition to prostate cancer surgery, other applications include gynecologic and cardiac surgery. “It's a function of time and investigation,” says Tewari. He also suggests that using robotics may extend a surgeons’ career, because it will help save hands, the surgeon can sit comfortably, sees better, and doesn't have to grip equipment tightly. There are also devices to reduce tremors.
Tewari's group is transferring the technology to other countries, including India and Singapore. He says residents are eager to learn the technique. He thinks familiarity with interactive computer-based gaming equipment is an advantage for younger surgeons. He notes that although the surgeon cannot rely on a sense of touch, he thinks this isn't important, because one can't feel the difference between cancerous and normal tissue and nerves and non-nerves. Diagnoses and the checking of margins for freedom from tumor cells are done by biopsy, and the lack of feeling is compensated for by better visualization. Although it's theoretically possible to add nanosensors, Tewari thinks it might increase the cost of the robotics he uses by a million dollars with today's technology.
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Wiens, on the other hand, believes that force sensing to assist surgeons is feasible, such as using a parallel robot that can perform in a haptic manner. These robots would provide surgeons with sensory input by amplifying forces to a detectable level. “Haptics is where we're going to see direct surgery,” she observes. She believes her group's force transducer might fit into this sort of system.
“There's been some amazing microsurgery, but it's still being done by surgeons controlling the input,” says Wiens. She notes that human input will be needed to determine what the controls should be. Complete autonomy of robotics removes the human from determining the input signals. Wiens notes that if autonomous robots are developed, safeguards will be needed. The process will have to be tightly controlled, and it may well need to be a human who hits the emergency stop switch if something goes wrong.
