2011 - Karthikeyan Ponnusamy - ClinicalOutcomesWithRoboticSurgery[Retrieved-2014!05!25]

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Clinical Outcomes With RoboticSurgery

For the last 60 years, robots have captured peoples imagination as the

embodiment of the technological promises of the future. Considering the

first definition for robot in the Merriam-Websters Dictionary is a

machine that looks like a human being and performs various complex acts

(as walking or talking) of a human being; also: a similar but fictional

machine whose lack of capacity for human emotions is often empha-

sized,1 it is no surprise that robots permeate science fiction literature and

films. Robots, such as Hondas ASIMO with its humanoid appearance

and ability to walk and run, have the highest public profile, but relatively

simpler robots are in more widespread industrial use. These robots meet

the easier standard set by the second and third definitions for robots in

Merriam-Websters Dictionary: a device that automatically performs

complicated often repetitive tasks and a mechanism guided by auto-

matic controls.1 The second definition partly arose from the origin of the

word robot, which was created by Karel Capek for his play 1921

Rossums Universal Robots.2 Capek derived robot from the Czech word

for slave labor, robota, because his play robots, built from chemical and

biological materials, are created to replace humans at mundane repetitive

labor, to provide humans more time for intellectual endeavors. With time

the robots eventually become superior to humans both physically and

mentally and endeavor to destroy humanity. Audiences became quite

upset by the play and feared for their jobs and lives. Later science fictionstories, such as the Terminatorand the Matrixtrilogies, struck this same

chord with their themes of robot rebellion.

In the robotics community, a more general and more commonly used

definition for robot was established by the Robot Institute of America in

1979: a reprogrammable, multifunctional manipulator designed to move

material, parts, tools, or specialized devices through various programmed

motions for the performance of a variety of tasks. The first programma-

ble manipulators were developed in the 1940s, and the technology wasfurther advanced by George Devol with inventions, such as a magnetic

Curr Probl Surg 2011;48:577-656.

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process controller that allowed manipulators to have a play back memory.Joseph Engelberger licensed Devols robot patents and created the

company Unimation in 1961, which was the first to commerciallymanufacture industrial robots.3 Unimations first robots went to theautomobile industry and helped with automating repetitive tasks. Since

then, the use of robots in industry has expanded and includes performing

dangerous jobs (ie, handling radioactive material, exploring space) andprecision machining, among others. These tasks generally fall under the

three As of robotics research, which are automation, autonomy, andaugmentation.4 The first Unimation robots were in the automation

category, where they performed repetitive tasks, and the majority of

industrial robots to this day are still classified as such. Autonomous robotsare starting to gain more use with advances in artificial intelligence (AI),

and their use includes space exploration and even cleaning, as demon-strated by the Roomba robot.4 The third category, augmentation, is

focused on humans and robots working together to become capable of

feats neither could perform alone. Human-controlled robots that performboth macroscopic and microscopic tasks fall under this category. The

most commercially successful surgical robot, Intuitive Surgicals da VinciSurgical System, also falls under this category.

The first reports of robots being used in the operating room are from the

mid-1980s, and multiple engineers and clinicians are responsible for theinitial robotic surgery studies conducted across a range of surgical

disciplines. One of these pioneers in robotic surgery, Brian Davies, had

developed a definition of robotic surgery based on the Robot Institute ofAmericas definition that has come to be accepted within the field. In his

2000 review, he defined a surgical robot as a powered computer

controlled manipulator with artificial sensing that can be reprogrammedto move and position tools to carry out a range of surgical tasks.5 Daviesgoes on to distinguish robotic surgery from computer-assisted surgery

(CAS) based on the fact that robots have their own motors to move,

whereas CAS requires the surgeon to provide motive energy. Nonethe-less, robots by their very nature of using computers to assess their

environment and control their actions are a subset of CAS.3 Davies alsowrites that robots should not replace the surgeon, but that the robot

should assist the surgeon while under his/her supervision.5 Althoughin the foreseeable future AI will not have advanced enough for robots tooperate independent from surgeon supervision, perhaps the time may

come when AI enables a robot to independently perform surgeries.

Consequently, for the purposes of our review of the field, we considerrobotic surgery to be a subset of CAS with the distinguishing aspect that

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it possesses independent motive abilities. With this clarification, we useDavies definition of robotic surgery without the qualification that the

robot must operate under a surgeons supervision.Robotic Surgery Classification

The field of robotic surgery has expanded since the 1980s to include

various systems, and classification systems for them are important infacilitating communication among all involved parties. Because robotic

surgery research brings together engineers and clinicians, the differentinitial classification schemes tended to appeal to 1 or the other. Engineers

tended to develop technology-based classification schemes similar to the

schemes used in the broader field of robotics (ie, imaging, controlsystems, etc), whereas clinicians were more apt to look toward clinical

application-based classification (ie, general surgery, neurosurgery, etc).

Several classification schemas have been proposed to provide utility toboth the engineers and the surgeons, but none of these has become the

standard for the field. Below we discuss the commonly cited classificationsystems, but for the purposes of our review of the field, we use the

surgical subspecialty categorization of robots for the discussion of clinical

applications since our target audience is clinicians.Davies in his seminal review in 2000 focused on robot movement, which

had been used asakey distinguishing feature from CAS, and whether it was

passive or active.5 Passive robots move to get in the appropriate position and

then can be powered off for the duration of the surgery. This is commonlyseen in robots used for stereotactic biopsy purposes where the robot aligns

itself with the target and then does not move until the surgeon completes the

biopsy. Active robots by contrast have manipulators with tools that directly

interact with the patient to perform the surgery, and the da Vinci SurgicalSystem is an example of this.

Taylor proposed using the role of the robot as the basis for classifica-tion. His classifications were intern replacement, telesurgical systems,

navigational aids, precise positioning systems, and precise path systems.4

Intern replacement robots, as the name implies, replace some of the roles

of surgical interns, such as holding laparoscopic cameras (AutomatedEndoscopic System for Optimal Positioning [AESOP] robot). In telesur-

gical systems, the surgeon directly controls the robot that performs thesurgery, as is the case with the da Vinci robot. This interaction with therobot provides additional benefits, such as tremor filtering and the ability

to operate at a distance. According to Taylor, navigational aids encom-

pass CAS systems that provide 3-dimensional (3D) localization toolsintegrated with patient-specific imaging. However, these navigational aid



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systems would not qualify as robotic surgery per Davies5 definition. Inthe case of systems that serve as navigational aids and have their own

motive power, they would be classified as precise positioning systems inthe Taylor categorization scheme. The last category is precise pathsystems, which go beyond the precise positioning systems in that they

move a surgical tool through a predetermined path. The classic example

is in stereotactic radiosurgery, where the robot moves the radiation beamthrough a predetermined path targeting the tumor.

Camarillo and colleagues3 proposed an alternate role-based categoriza-tion scheme focusing on the robots role in the surgery and labeled them

as passive, restricted, or active. The key aspects for a passive robot are

that its role has a limited scope or its use is low risk. Restricted robotshave a greater role and are involved in more invasive and higher risk

tasks, but are still limited from core aspects of the surgery. Active robotshave an even greater involvement and are intimately involved in the

procedure and carry high responsibility and risk.3 This system can be

viewed on a continuous scale rather than a simple discrete classification;even robots within the same category can carry relatively different levels

of invasiveness and risk. Camarillo and colleagues3 plotted autonomy vsthe robots procedural role for currently available robots and identified an

indirect trend (Fig 1). The robots with the least risk and invasiveness tend

to have the greatest autonomy, and the inverse is true as well.Bann and colleagues6 proposed using a 2-group classification scheme

with the first based on function(similar to the role focus used by Taylors4

and Camarillo and colleagues3 classifications) and the second based on

technology. Their function-based classification (dexterity enhancement,

precision localization, and precision manipulation) is analogous to Tay-

lors4 role-based system categories (telesurgical systems, precise posi-tioning systems, and precise path systems). The second group of tech-nology classification focuses on the interaction between the surgeon and

robot, and the categories are autonomous, supervisory, and teleoperated.

Autonomous robots execute a preoperative plan programmed by thesurgeon. Supervisory robots work together with the surgeon to guide

him/her through the procedure. Teleoperated systems are similar to

Taylors4 telesurgical systems. Bann and colleagues6 brought a unique

perspective to categorization by considering 2 groups for each classifi-cation, but as can be seen from their scheme, the 2 groups do not assessindependent characteristics since dexterity enhancement systems by

definition will always beteleoperated systems as well.

Nathoo and colleagues7 proposed another 2-group classification system

based on technical and interaction classifications. The technical classifi-



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cation is divided into active and passive similar to Davies5 active andpassive classification. The 1 difference is that Nathoo and colleagues7

define a passive system as 1 where the surgeon provides the motive force

to position the robot and then the robot is powered-off instead of the robotcausing the motion. The interaction classification is based on how the

surgeon interacts with the robot; the categories were divided intosupervisory-controlled, telesurgical, and shared-control systems. Thisclassification is comparable to Bann and colleagues6 technology

group. Supervisory-controlled systems are like Bann and colleagues6

autonomous robots in that the surgeon programs the robot before the

procedure. Shared-controlled systems are called such because controlof the surgical tools are shared with the surgeon and would fall under

Bann and colleagues6 supervisory category. Last, telesurgical sys-

tems are similar to Taylors4 telesurgical and Bann and colleagues6

teleoperated systems.

Surgical Robot CharacteristicsBased on Davies5 definition of surgical robots, the essential compo-

nents of a robot can be broken down to a computer, artificial sensors, and

FIG 1.Plot of surgical robot autonomy versus robots procedural role (passive, restricted, or active).The robots with the least risk and invasiveness tend to have the greatest autonomy, and the inverse is

true as well. (Reprinted with permission from Camarillo et al.3)



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manipulators. The various available robots each have different capabili-ties in each of these aspects.

ComputerTeleoperation/Telerobotics/Telepresence. One important feature that

some systems offer is remote control. Satava and Simon8 described the

different kinds of remote control and they are teleoperation (direct robotcontrol via master-slave system), telerobotic (the robot has the intelli-

gence to perform the procedure on its own and the surgeons supervises),and telepresence (similar to teleoperation with additional sensory input

that would allow the master and slave to be physically separated by long

distances yet feel as though they are not separated). As a word ofclarification regarding the categories discussed inthe prior section, Bann

and colleagues6 teleoperated and both Taylors4 and Nathoo and col-leagues7 telesurgical systems would only include robots that Satava and

Simon8 would classify as telepresence. Satava9 later reported that

telesurgery was equivalent to telepresence. For the rest of this review,Satava and Simons8 definitions will be used.

Teleproctor. Another feature that some robots may have included isteleproctoring, where an experienced surgeon can remotely follow and

guide another surgeon through an operation. This can be quite useful for

clinicians located in isolated areas who may not have the experiencetreating certain diseases. Teleproctoring can be used locally as well for

resident education. Surgical residents and fellows can train to use the

robotic system with guidance from the attending surgeon providedthrough the systems interface.

Artificial SensingSensor Types. Robotic surgery systems can study their environment

with a variety of sensors. Some, such as propioceptive sensors at joints,

can help the robot to identify its location within 3D space. Other sensors,

such as cameras and ultrasound, can relay information to the surgeon toprovide them with the necessary sensory information to perform the

procedure. These sensors can convey the sensory information to the

surgeon by the same means it was gathered (ie, transmit visual informa-

tion visually) or via synesthesia through another sensory modality. Anexample of synesthesia would be a robot that emits an auditory warningfor when instruments are at risk of colliding.

Haptics.Haptics qualify as a type of robotic sensor, but since surgeons

place a unique value on this set of sensation, we discuss it separately. Thenature of surgery before robotics was to work directly with ones hands,



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and that provides the advantages of using the evolutionary advanced

human hands natural haptic sensor system. These sensors provide a range

of sensations, including force, pressure, texture, and temperature thatsurgeons have integrated into the art of medicine. Okamura10 reports that

both cutaneous (tactile, ie, texture) and kinesthetic (ie, force) sensations

are necessary to simulate haptics felt by the human hand. In certain

robotic systems, such as Nathoo and colleagues7 shared-controlled

systems, the surgeon shares control of the surgical tools with the robot

and depending on the design of the system the surgeon can use their

natural haptic system as usual. However, with other robotic systems (ie,

teleoperated systems), the surgeon interacts with the robot controls andnot directly with the tissue and will miss the haptic sensations. These

robots can integrate haptics into the operative experience in multiple

ways, including directly through the controls or with synesthesia. The

most natural interaction for surgeons would be for haptics to be integrated

directly into the controls. As Okamura10 discusses in her article, there are

multiple technical challenges that arise in integrating haptics into the

controls because reliability and stability of the controls must be ex-

changed for greater haptic feedback. Consequently, Okamura10

suggestsusing synesthesia, such as with auditory and visual signaling as a

workaround for these challenges. Her laboratory has conducted initial

studies focusing on conveying force feedback, and Okamura10 reports

that in the systems they tested visual feedback played a more dominant

role than auditory feedback.

Preoperative Image Registration. Robotic surgery systems have the

potential to integrate preoperative imaging, such as computed tomogra-

phy (CT) and magnetic resonance imaging (MRI) scans with their sensorsystems to provide targeted guidance for the procedure. The key to these

systems is to register the preoperative images with the operating room

setup. In other words, the robot needs to calibrate the images to reference

points on the patient. Some systems require that fiducials, physical

reference points, such as stereotactic frames or radiographic markers, be

attached to the patient either before preoperative imaging or after in order

for the robot to calibrate its position with respect to the imaging. Certain

registration programs demand that fiducials must be physically embeddedon patient landmarks, such as on bone. These fiducials can be painful and

may even require general anesthesia if used on children.11 Noninvasive

fiducials include dental molds but have the concern that accuracy may be

compromised. The CyberKnife system uses regular high-precision x-ray

images to register the patient and does not require the use of fiducials, yet



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is able to provide highly accurate positioning.11 Adoption is likely to begreater with systems that do not require invasive fiducials.

Another important consideration for image registration depends on thetissue consistency. Hard tissues, such as bone, once rigidly fixed willgenerally not deform or move with the forces applied during a procedure.

By contrast, soft tissues will tend to deform and move with manipulation,

and the preoperative image registration would likely become invalid assoon as the procedure begins. Two approaches to address this problem

have been to use intraoperative imaging or modeling soft tissue defor-

mation.12 Depending on the tissue and the manipulation involved, regular

or real-time updates can be used to adjust the image registration

throughout the procedure. Some intraoperative imaging techniques thatcan be used include fluoroscopy, CT, MRI, and ultrasound. Modeling of

soft tissue deformation with manipulation has been a more challengingmethod to address this problem due to the number of variables involved

in accurately predicting the biomechanical properties of different

tissues.12

ManipulatorsDegrees of Freedom. The manipulators degrees of freedom (d.f.)

represent the number of independent motions that the manipulator can

execute. For the robot manipulator to navigate in 3D space, it will needat least 3 d.f., 1 each for the x-, y-, and z-axis. In order for the robot to

conduct certain surgical tasks, such as suturing, an additional 3 d.f. withpitch, yaw, and roll are needed to greatly facilitate surgical ease.

Sometimes grip is considered a seventh d.f. Manual laparoscopic instru-

ments generally have 4 d.f. (roll, x-, y-, and z-axis) and grip can be

considered as a fifth d.f.End-Effectors.The end-effectors are the surgical tools that the manip-

ulator is using. These tools include standard surgical instruments (grasp-ers, needle drivers, scalpels, etc), energy-based instruments (electrocoag-

ulation, laser, ultrasonic scalpel, etc), and linear accelerators for

radiosurgery. End-effectorscan be diagnostic tools like ultrasound probesand microscopy equipment.13 The d.f. for each instrument can be limitedby the nature of the tool; a scalpel will not have grip or an ultrasonic

scalpel will have limited pitch and yaw.Footprint. Depending on the footprint of the robotic systems equip-

ment and manipulators or in other words the space they need to function,

a larger operating room facility may be necessary. In addition, the use of

other equipment, such as fluoroscopy or intraoperative CT or MRI, maybe limited or impossible if the robotic system has a large footprint



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requirement. Depending on the amount of space the robot occupies nearthe patient, patient-side surgeons may be limited in their ability to work

with the robot.Workspace. The robots workspace is definedas the volume of spacewhere the robot can reach with its manipulator.3 The constraining factors

for workspace are the manipulator arm lengths, joint bending limits,

collisions between arms, and anatomy. At the edges of the workspace, themanipulator may not have its full d.f. available for use since it is at an

extreme position. Consequently, the target anatomy of a surgical proce-dure should be kept in the center of the workspace to avoid limiting the

manipulators effectiveness.

Limiting the workspace can be used by some robots as a safetymechanism to prevent accidental injury to the patient. A system where the

workspace is limited such that all possible motion within that volume is

safe is called an intrinsically safe design.7 The limits can be due to either

hardware (difficult to design a robot useful for patients of all shapes

and sizes) or software. Hardware limits cannot be overcome inadver-tently, but software limits (although more flexible across patients) can

have its intrinsically safe design circumvented by software errors orimproper use.

Resolution. The robots resolution is defined as the smallest unit of

motion that the manipulator can move or measure.3 The necessaryminimum resolution for a robot depends on its clinical applications and is

commonly assessed in units of length. For example, to perform acholecystectomy, a robot would need a resolution of at most 2 mm3.

However, some ophthalmologic microsurgeries require resolutions 2

orders of magnitude smaller (less than 25 m).13,14 As a comparison, the

limits of human performance are around 200 m.13

Inertia, Force, and Speed. A robots inertia depends on the mass,shape, and size of the manipulator. The greater the inertia, the stronger the

driving motors need to be to achieve a given speed or force. The motors

are connected to the manipulators via a transmission that takes advantageof mechanical advantage principles to scale-down the speed to scale-up

force. In order for the speed to be increased, the mechanical advantage

needs to be decreased, resulting in a decreased force. Both speed and

force can be increased with even stronger motors and an appropriatetransmission.

Force Dynamic Range.A robots force dynamic range is defined as the

ratio between the greatest and smallest force that it can control.3 Creatinga vessel anastomosis, such as a coronary bypass, requires a robot capable

of both high-resolution and small force control, whereas for bone drilling



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for orthopedic, neurosurgical, or ear, nose and throat applications, therobot needs a high force control to use drills and saws. Similar to the case

with resolution, robots need to match their force dynamic range with theclinical application demands.

Stiffness.The stiffness of the manipulator depends on the materials it is

composed of and its design. A stiff manipulator will allow greater control

and accuracy because it is less likely to be deformed away from itsexpected location.3 However, a less stiff manipulator is less likely to

impart damage to soft tissue structures if the manipulator inadvertentlyhits it.

Backdrivability. Backdrivability is the ability for the surgeon to

manually move the manipulator out of the way. Because of the potentiallyhigh mechanical advantage used in the transmission, it could be very

difficult to manually move the manipulator out of the way without usingthe controls. In emergency situations where the procedure must be

converted from robotic to traditional approaches, backdrivability is

essential to move the robot out of the way to quickly provide the surgeonthe space and access needed to stabilize the patient. A solution used by

some robots is to use a clutch to disengage the manipulators from the

transmission and allow the surgeon to both easily and quickly move therobot.

Position Control and Force Control. The robot manipulators can be

manipulated with multiple control schemes. One is position control wherethe manipulator is moved through a specific path. In force control, the

robots interactions with specific surfaces are limited to a predeterminedrange of forces. Too much force can result in tissue damage, but too little

force with certain instruments, such as a bone drill, can cause the drill bit

to jump, causing injury elsewhere. It is thought that human surgeons usean innate combination of position and force control when operating.3

Depending on the application, robots can have better control using a

similar combined position and force control.

Bandwidth of Motion and in Force.Bandwidth of motion is defined asthe highest frequency the controls can be oscillated such that the

manipulator can continue to track the controls. At any higher frequency,

the manipulator would fall behind the controls and would not accurately

follow the input commands. The manipulators inertia, speed, andstiffness all play a role in determining the bandwidth. Bandwidth ofmotion is a very important consideration in teleoperated systems where

master movements are expected to temporally correlate with the slave. In

any procedure, the bandwidth of motion must be higher than thefrequency at which the surgeon controls the master. Bandwidth of motion



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is directly correlated with the position control, in that this bandwidth

determines the fidelity with which the position control commands are

executed by the manipulator.Similarly, bandwidth in force is related to the force control and is the

highest frequency at which the manipulator can track force commands

from the controls. In this case, the manipulators force, force dynamic

range, and stiffness all affect bandwidth in force. In manipulators with

bone drills as end-effectors, force controls must recognize sudden

changes in force that may signal a possible bone fracture or shift in the

drills position and require sufficient bandwidth in force to quickly adjust

the manipulator to avoid injuring the patient.Mechanism Type. Another feature of the manipulators is how the

end-effector is attached to the rest of the robot or the mechanism type.

The traditional mechanisms are by serial or parallel linkages. One of the

major advantages of a serial linkage is that the manipulator will have a

larger workspace with smaller footprint than a similarly designed system

with parallel linkage. A movable desk lamp is an example of a serial

linkage that takes advantage of this system to provide lighting for the

entire desk.

3

Parallel linkages have multiple connections between jointsthat make the joint stiffer, allowing it to carry heavier loads and have

improved accuracy, with the cost that there is a smaller workspace and

larger footprint. An example of a parallel linkage is a scissor jack used for

lifting a car; it demonstrates the advantages of a stiff joint in holding up

a car.3 Some current robotics systems may not even have a direct

mechanical link and cannot be classified into these 2 categories. For

example, the Niobe robotic catheter system produced by stereotaxis

controls the catheter with magnets.

History of Robotic SurgeryRobotic surgery came into existence during the 1980s, with multiple

researchers around the world both adapting industrial robots and creating

novel systems for use in surgical procedures across a range of specialities.

The first reported use of a robot for surgery was for a stereotactic

neurosurgical biopsy in April, 1985.15 Neuromate, Probot, ROBODOC,

Acrobot, precursors to da Vinci, and AESOP/HERMES are robots thatwere developed in the late 1980s and early 1990s. We discuss the

development of these robotic systems because of their prominence in

the history of robotic surgery. Other robotic systems developed during

the late 1980s through the 1990s include Artemis, Minerva, CASPAR,

and EndoAssist.13



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Kwoh and colleagues Neurosurgical Biopsy RobotKwoh and colleagues15 noted that the problems of traditional manual

stereotactic biopsies were that they were time-intensive and manual frameadjustments led to potential inaccuracies. They wanted to develop a

means to automate the process to increase precision and speed, and they

decided that a robot could achieve these goals. They adapted a commer-

cially available Unimation Programmable Universal Machine for Assem-

bly (PUMA) 200 robot for their biopsy system. The procedure started by

attaching a stereotactic frame to the patients skull to take the necessary

CT images. Once the target is identified on the images relative to the

frame, the robot is attached to the frame for registration and then it swingsits manipulator to direct the probe toward the target. Surgeons are able to

reposition the manipulator trajectory to avoid critical neurological struc-

tures, while the robot maintains alignment with the target. As the first use

of a robot for surgery, Kwoh and colleagues15 conducted numerous tests

(including experiments simulating a patients head with a watermelon and

a lesion with a lead BB) to insure safety and accuracy before proceeding

with human tests. These studies indicated that with calibration the robot

could direct a needle tip within 1 mm of the target. Kwoh and colleaguesproceeded to test the robot in a patient in April, 1985, and successfully

biopsied a suspicious brain lesion on the first attempt.15

NeuromateA couple years after Kwoh and colleagues15 performed their first

robotic biopsy, researchers at Grenoble University in France published

their initial report of developing a stereotactic robot using a Unimation

PUMA 200 Robot.16 Their system has been improved over the years andis used for tumor biopsies, stereoelectroencephalographic investigations

for epilepsy, and functional neurosurgery electrode placement. The initial

system design required that the patient have preoperative CT or MRI

imaging while wearing a stereotactic frame with built-in fiducials. The

images are incorporated into the planning software and the surgeon then

programs the target and trajectory that is sent to the robot. In the operating

room, Neuromate is registered by taking 2 x-rays of the patient with a

stereotactic frame and a calibration cage around their head and attachedto the end-effector. The calibration cage is shaped like a cube and has 9

precisely positioned x-ray beads in each of the 4 sides to help the software

register the position of the robot relative to the preoperative imaging; the

robot is locked in this position to maintain the registration. Then, the

end-effector is switched to a guide and the 6-axis passive manipulator



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positions the guide with the preoperatively determined starting point andtrajectory. The surgeon can proceed with the surgery using the guide to

perform the procedure.

14

ProbotIn 1988, Sir John Wickham, MD, a urologist, and Brian Davies, PhD,

at Imperial College London in London, adapted a PUMA 560 industrialrobot foruse in transurethral resection of the prostate (TURP) and named

it Probot.5 They had recognized that the traditional means of performingTURPs took nearly an hour to perform and required the surgeon to be in

an awkward position for the entire procedure. More importantly, the

conical section removed in a TURP could be relatively easily pro-grammed for an autonomous cutting robot.17 In their initial studies

simulating a prostate with a potato, once the robot was positioned in theinitial position it was able to perform the necessary cuts in approximately

5 minutes.17 Probot needed 8 d.f. to perform these cuts and this

flexibility added additional safety concerns for using this industrialrobot. Consequently, this research group developed and validated a

circular ring that limited the movement of the cutting tool and wouldmake the system intrinsically safe to prevent inadvertent patient injury

by cutting tissues beyond the prostate. With the establishment of these

safety mechanisms, the Probot performed its first surgery on a patientin April, 1991 (Fig 2).5

ROBODOCDuring the early 1990s, Howard Paul, DVM, and William Bargar, MD,

were both interested in total hip replacement/arthroplasty (THA) surgery;

Paulwas involved with dog THA, while Bargar was involved with humanTHA.13 At the time the trend in THA was toward cementless femurcomponents, with the goal of having bony ingrowth into the implant.

There was concern that the manual technique of using reamers and

broaches resulted in gaps between the implant and bone that inhibitedingrowth.18 Consequently, Paul and Bargar teamed up with Russell

Taylor (mentioned previously for his classification scheme) and adapteda Sankyo-Seiki industrial robot for their purposes. For safety, they added

redundant force, torque, and position sensors for a combination of forceand position control.18 Their robot is able to provide accuracy within 0.1mm and, depending on the resolution of theCT scan, the overall accuracy

for preparing the femur is within 0.4 mm.18 Additional tests showed thatmanual broaches resulted in75% accuracy, but ROBODOC could prepare

femurs with 96% precision.13



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The procedure starts with the placement of 3 percutaneous titanium pins

(fiducials) in the medial and lateral condyles and greater trochanter. A CT

scan of the femur is taken and imported into the ORTHODOC softwarethat they developed to help identify the appropriate implant and program

the ROBODOC. Then, the patient is brought into surgery and a traditional

posterior approach to the hip is used to position the acetabular compo-

nents and expose the femoral neck. The neck is cut 2 to 3 mm proximalto the desired cut, because ROBODOC will adjust for the difference.Next, the femur is attached to an external fixator via a clamp at the lesser

trochanter and 2 halo pins are placed immediately proximal to the

condylar fiducials. The external fixator is directly connected with therobot, and then the robot registers its position as the surgeon moves

FIG 2.Probot with intrinsically safe circular ring to prevent inadvertent cutting beyond the prostate.This was the first time that a robot was used clinically to remove tissue from a patient in April, 1991and shows the urologist, Mr Wickham, operating. (Courtesy of Professor Brian Davies, ImperialCollege London of London and copyright Stanmore Implants Worldwide Ltd.)



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the manipulator with a ball probe at the end to identify each of the 3fiducials. After the software calculates the necessary paths, a standard

surgical burr is switched for the ball probe and the robot executes thepreoperative plan. After the femoral cavity is prepared, the robot is movedout of the way and the surgeon implants the femoral component. The

incision is closed with traditional means.18

Paul and colleagues18 reported their initial success in 25 dogs and did

not have any intraoperative complications or postoperative infections.

This led to the first human trial in 199219 and completion of a successful10 patient human feasibility trial that demonstrated safety. To determine

efficacy, a Food and Drug Administration (FDA) trial was conducted in

the United States (65 ROBODOC THAs) and a postmarket study wasconducted in Germany (900 ROBODOC THAs) starting in 1994.20

Advantages associated with using ROBODOC included no intraoperativefemur fractures and the various measures of implant fit were significantly

improved with the robot. It is theorized that implant fit is correlated with

long-term outcome, but that remains to be seen. These studies had at most2-years follow-up that did not show any statistically significant difference

in functional outcome. The disadvantages of ROBODOC were significantincreases in blood loss (EBL) (1189 mL vs 644 mL) and operative time

(OT) (258 minutes vs 134minutes). The EBL was directly correlated with

OT. Bargar and colleagues20 reported that with experience the additionalOT of using ROBODOC decreased to an extra 30 minutes compared to

manual techniques.

AcrobotAcrobot, named for being an active constraint robot, was developed at

the Imperial College London by Davies (who was involved with theProbot) and Justin Cobb, MD.21,22 Instead of adapting an industrial robot,they developed their own device for the purpose of making the cuts

needed for a total knee replacement/arthroplasty (TKA). Unlike

ROBODOC with its autonomous execution, Acrobots manipulator ismoved by the surgeon throughout the procedure and offers the surgeons

natural haptic feedback for cutting while actively constraining the range

of motion as a software-based intrinsically safe system. Preoperatively a

CT scan of the patients affected leg (1-mm slices at the knee and 5 mmfor the rest of the leg) is acquired, and the surgeon uses the Acrobotsoftware to plan the appropriate cuts for the desired implant. During the

surgery, the traditional medial parapatellar approach to the knee is

used to acquire the necessary exposure. The femur and tibia areimmobilized at the knee to the operating table via clamps. The distal tibia



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is rigidly held with a foot support, while the patients weight is sufficientto hold the proximal femur. The robot is brought in and locked to the

operating table to put it in rigid continuity with the femur and tibia.Acrobot uses an anatomical registration method (iterative closest pointalgorithm) that does not require fiducials. The surgeon moves the

manipulator with a ball probe at the end to 4 landmarks on the patient, and

from that the robot creates an initial registration. Then, the surgeonrandomly tests 20 to 30 points on the bone to check accuracy, and if

insufficient, registration is redone. Once suitable registration accuracy is

achieved, the surgeon proceeds with the femoral and tibial cuts using theAcrobot manipulator programmed with the predetermined constraints,

while the patella cut is performed manually due to its simplicity. Initialclinical trials demonstrated promise, although the OT were longer than for

traditional techniques.22 Stanmore Implants Worldwide Ltd. currentlyproduces the most recent iteration of the Acrobot system (Fig 3).

Precursors to the da Vinci Surgical SystemThe origins of the da Vinci robotic surgery system are rooted in research

conducted at the Stanford Research Institute (later renamed to SRIInternational), National Aeronautics and Space Administration (NASA),

and the Defense Advanced Research Projects Agency (DARPA, previ-

ously known as ARPA). During the late 1980s, Joseph Rosen, MD,completed the Stanford University plastic surgery residency and then

joined the faculty there. He was interested in the potential for robotics to

be used in hand surgery specifically for nerve and vessel microsurgery.Together with Philip Green, PhD, an engineer at SRI, they worked on

developing a dexterity enhancement robot with a telesurgery system.

During this time, they met Scott Fisher, PhD, who was in the laboratoryof Michael McGreevey, PhD, and Stephen Ellis, PhD, at the NASA Ames

Research Center where they were working on virtual reality environ-ments. They teamed up with the vision to create a virtual reality

environment through a head-mounted display to simulate being at the

operating table and the surgeon controlled the robot with gloves thatrecorded hand movements. Because of technology limitations on the

resolution of head-mounted displays and gloves, the team decided to use

a monitor and controllers for the surgeon console. The slave in this systemwas a 2-armed robot that was equipped with switchable instruments.23

Richard Satava, MD, a general surgeon with the Army in Monterey,

CA, heard about and became interested in the telesurgery project, and he

subsequently joined the team as an additional researcher. Soon thereafter,Satava was at the 1989 Society of American Gastrointestinal Endoscopic



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Surgeons, where he saw Jacques Perrisats video of the first laparoscopic

cholecystectomy. Satava brought this insight to the group and they addedlaparoscopic general surgery as another clinical application to explore,

but they devoted most of their energies to hand and open general surgeryprocedures. One of the demonstration tests they conducted with their

robotic system was for bowel anastomosis with an open technique. Wordof this spread through the military, and Satava was promoted to programmanager for Advance Biomedical Technologies at DARPA in 1992.

From analysis of soldier injuries, it was determined that 90% of

battlefield deaths occur before the patient can be transported, oftentimesdue to major vessel hemorrhage from delayed surgical intervention.13,23

FIG 3.Most recent iteration of the Acrobot robot. (Courtesy of Stanmore Implants Worldwide Ltd,

United Kingdom).



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Satava oversaw a project to further develop this robotic system for use inan armored vehicle called the Medical Forward Area Surgical Team

(MEDFAST) to stabilize the injured soldier with open surgery while theyare being transported to the Mobile Advanced Surgical Hospital (MASH)located 10 km to 35 km behind the line of active combat. The surgeon

would operate from the console based at the MASH and continue to take

care of the patient once they were brought in by the MEDFAST. In trialsof this system in 1994, the first remote telesurgical procedure was

conducted via a microwave connection between a MASH and a

MEDFAST up to 5 km away. The surgery in this case was the ex vivoanastomosis of porcine intestine. This DARPA project was eventually

discontinued before implementation because the battlefield was changingfrom open areas that a MEDFAST vehicle could quickly navigate to the

urban environments of current wars. For more details about these

developments and the researchersinvolved, see the articles on the historyof robotic surgery by Satava.9,13

In 1995, Frederic Moll, MD, cofounded Intuitive Surgical and licensedthe telesurgery system from SRI together with patents from International

Business Machines and the Massachusetts Institute of Technology.9,23

Their robot was named the da Vinci Surgical System and focused on

minimally invasive surgery. Intuitive wanted to overcome the limitations

of laparoscopic instruments, includingthe fulcrum effect, limited dexter-ity, and loss of 3D vision with robotics.13,23 The key goals of the Intuitive

system were to develop a master-slave system with intuitive control,stereoscopic vision, a design with redundant sensors to maximize safety,

and laparoscopic instruments with 7 d.f.23 The system was used in March,

1997, for the first cholecystectomy telesurgery in a human.24 After a 200

patient randomized clinical trial to test safety and efficacy in cholecys-tectomy and Nissen fundoplication, the da Vinci robot received FDAapproval in July 2000.23 The initial clinical focus for the robot was for

endoscopic coronary artery bypass grafts (CABGs), but the da Vinci

system has gained significantly greater adoption in other subspecialties,such as urology and gynecology.13

Computer Motion

Yulan Wang, PhD, was an entrepreneur interested in medical applica-tions for robotics and founded Dynamic Microsystems in 1989 (laterrenamed Computer Motion in 1990) with grants from NASA and the

National Science Foundations Small Business Innovation Research

Program.25 Computer Motion focused its efforts on developing a robotic

laparoscopic camera holder called the AESOP and received DARPA



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support for it in 1993.9,25 In the original version of AESOP, the surgeon

controlled the camera direction with either hand or foot controllers that

moved the view relative to the current camera position.The views couldbe saved and returned to with a press of a button.26 Later, voice

recognition and control was added as another option. AESOP was the first

surgical robot to receive FDA approval, in 1993, 1 month after its first use

in a laparoscopic cholecystectomy.25

After its success with AESOP, Computer Motion solicited and acquired

additional financing from the private sector to produce a complete robotic

system with surgical manipulators.9 In 1995, they began development of

a new robot that was based on 3 AESOP arms, 1 for the camera and 2 for

surgical instruments. This system was called ZEUS and was a master-

slave system that offered motion scaling and tremor reduction for

laparoscopic and other minimally invasive surgeries.25 Highlights of

ZEUS include the first robotically assisted CABG in September, 1998,

and the first transatlantic telerobotic surgery (a cholecystectomy) by

Jacques Marescaux, MD, in September, 2001. Around this time, ZEUS

received limited FDA approval for abdominal procedures.25 Intuitive

Surgical acquired Computer Motion in 2003 due to a variety of financial

and legal disputes, andsince then, the AESOP and ZEUS systems have

been discontinued.9,25

Commercially Available or Near Market SurgicalRobots

Since these early robotic surgery endeavors, numerous research labo-

ratories around the world have embarked on developing new robotic

systems for use in various clinical applications. Many of these projects arestill in the early stages of development and are years away from

widespread clinical use. The focus of our review is on the clinical value

of currently available systems, and, consequently, for this section we

discuss commercially available or near market systems. For a summary of

the cutting-edge research developments in robotic surgery, see the

reviews by Dogangil and colleagues12 and Pott and colleagues.27

NeuromateSince its development, Neuromate has gone on to commercial produc-

tion initially by Integrated Surgical Systems with FDA and European

approval.14 Commercialization rights were later transferred to Schaerer

Mayfield Neuromate AG,28 which was later acquired by Renishaw PLC,

which currently manages production and sale of Neuromate.29 They



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advertise that the Neuromate system can currently be used for electrode

placement for epilepsy monitoring, therapeutic neuroendoscopy, deep

brain stimulation, biopsy, neuro-oncology drug delivery, transcranialmagnetic stimulation, and radiosurgery (with miniature radiation source

end-effectors).29 One of the major updates in the last decade to the

Neuromate system is the incorporation of frameless registration, although

this process still has an invasive component. This new registration process

starts with attachment of a base plate with a 4-spoked fiducial system to

the patients skull under local anesthesia. Accuracy of the registration can

be measured by affixing 3 fiducials to the skull. Preoperative imaging is

then acquired with CT or magnetic resonance modalities. To register therobot, in the operating room, a 4-spoked ultrasound microphone system

(identical in shape as the spoked fiducial system) is attached to the base

plate. A similar system of ultrasound emitters is placed on the Neuromate

end-effector and the robot registers the preoperative imaging based on the

microphone readings. From laboratory and clinical studies, the mean error

was less than 2 mm, which was similar to results when using the

frame.28,30 The current system sold by Renishaw can be used with a

commercially available stereotactic frame or with the frameless system.29

NeuroarmGarnette Sutherland, MD, a neurosurgeon at the University of Calgary,

conceived the idea of performing surgery while an MRI machine is taking

its images. To achieve this goal, he and his colleagues developed the

NeuroArm, an MRI compatible robot. This system fits inside the MRI

bore and can be controlled while imaging is acquired without degradingthe quality of the images. Neuroarm is composed of a workstation

(master) and 2 manipulators (slaves) and can function in either a

stereotactic or a microsurgery mode. The stereotactic mode uses 1

manipulator positioned in the MRI bore and uses almost real-time

imaging for stereotactic surgeries. For microsurgery, the procedure is

performed outside of the MRI with both manipulators and uses a

registration system to overlay the intraoperative MRI images on the

workstation monitors. Although the manipulators are capable of 50-mresolution, the visualization is not at a high enough magnification for

surgeons to take advantage of this capability. Each slave has 7 d.f., moves

using ultrasonic piezoelectric motors, and has 2 strain gauges to provide

haptics information through the controls.31,32 Early clinical tests using the

NeuroArm in a series of 5 patients have been published.33



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CyberKnifeJohn Adler, MD, recognized that frame-based stereotactic radiosurgery

could only be applied for intracranial pathologies and that the frame led

to pain due to its invasiveness. His goal was to develop a system toaccurately deliver radiation to lesions anywhere in the body with

noninvasive image registration. Adler led a team that successfully

developed thefirstiteration of such a robot, CyberKnife, to achieve thesegoals in 1987.11,34 CyberKnife has a 6 d.f. linear accelerator end-effector

that moves through a hundred positions for each patient to concentrate a

lethal dose of radiation at the target while only minimally affectinghealthy tissue (Fig 4). Accuray was founded to commercialize this robot

in 1990, and since then, the system has received FDA approval for use inthe head, neck, and upper spine in 1999 and for the whole body (treatm ent

is referred to as stereotactic body radiation therapy [SBRT]) in 2001.34

Before treatment, a CT scan (or MRI) is taken from above the top of the

head to below the chin (for intracranial lesions). The surgeon or radiation

oncologist then plans the treatment in conjunction with the CyberKnife

software to target the lesion and avoid/minimize radiation trajectoriesthrough sensitive tissue. During treatment, the patient lies on a bed as theydid for the CT scan. Beside the patients head are 2 x-ray fluoroscopes

that take images of the patients skull and are registered with digitally

reconstructed radiographs from the CT. This allows the robot to identifythe lesion in 3D space and moves to 1 of a hundred nodes (beam

FIG 4.CyberKnife procedure room with robot and linear accelerator. Fluoroscopic images are takenwith the ceiling-mounted sources and detectors embedded in the floor. The Synchrony RespiratoryTracking System is attached to the ceiling on the left side of the room. (Courtesy of Accuray, Inc,Sunnyvale, CA.)



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origination positions) and delivers the appropriate radiation dose to thetarget. Before the robot delivers the next dose from a different node, the

fluoroscopes repeat imaging to update the registration to adjust for patientmovement. The registration is typically updated every 20 to 40 seconds.From the study by Adler and his colleagues, the precision of this

registration system is similar to that offered by a stereotactic frame.11

Variations to this general setup are used to accommodate treatment of

lesions elsewhere in the body, such as deformable organs. Spinal lesions

are tracked with Xsight tracking; this system uses the preoperative CTscan to construct digitally reconstructed radiographs and uses software to

identify key spinal landmarks to register theimage with the images taken

from the fluoroscopes in the procedure room.35 Thoracic, abdominal, andpelvic targets movements with respiration can be followed with the

Synchrony system that tracks respiration by following chest-mountedlight-emitting diodes and fiducials placed in the tumor. Using the

fluoroscopic imaging, the movement of the 2 is used to build a model of

movement such that radiation therapy can be delivered throughoutrespiration.36 For lung lesions, the robot uses the Xsight Lung (also

referred to as Lung Optimized Treatment) system, which was recentlyapproved by the FDA in December, 2010.37 The CyberKnife system is

being investigated for use in tumors throughout the body, chronic back

pain, obsessive compulsive disorder and other psychological diseases,and cardiac ablation. Hara and colleagues36 thoroughly review the use of

the CyberKnife for tumor treatment throughout the body from a radiationoncologists perspective.

MAKO Robotic Arm Interactive Orthopedic System

MAKO Surgical Corporation was founded as a spin-off from Z-KAT,Inc in 2004 to focus on the orthopedic robotics market.38 They focused onimproving unicompartmental knee arthroplasty (UKA) with robotics,

because research suggested that inaccurate component positioning led to

early failure and manual approaches led to significant positioning vari-ability.39,40 Consequently, MAKO developed its initial robot the Tactile

Guidance System (TGS) to improve component positioning for medialUKA. TGS is a shared-control system where the surgeon controls a burr

that is actively constrained to preoperatively determined safe zones,similar to Acrobot. A preoperative CT scan from the hip to the ankle withfiner 1-mm cuts through the knee is used with the software to determine

the necessary boundaries for appropriate implant positioning. Intraoper-

atively, the system registers the imaging initially with an optical infraredcamera to recognize navigation markers placed in the femur, in the tibia,



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and on the robotic arm. Key landmarks are then identified, such as the hipcenter (by circumducting the hip), ankle malleoli, femoral epicondyles,

and base of the anterior cruciate ligament. Based on this, a virtual kneemodel is built and the camera can move the virtual model in real-timewith knee movements. As a result, the leg does not need to be rigidly

fixed (unlike the original Acrobot) and can move while burring. For

safety, the burr is stopped if the knee moves too quickly.40 The surgeon

uses the active constraint robotic burr to prepare the femur and tibia, and

the cuts can be verified using a probe end-effector on the cavity or on topof the articular surface of trials positioned in the cavity.39,40 The camera

can be used to provide the surgeon additional information regarding

alignment and knee kinematics, and onceproper positioning is confirmed,the implants are cemented in position.40

Since the commercialization of TGS, MAKO has developed an updatedversion that is named Robotic Arm Interactive Orthopedic System (RIO)

that received FDA approval in 2008. This system is able to prepare both

the medial and the patellofemoral knee compartments unlike the TGSsystem that could only prepare the medial compartment. MAKO also

developed the RESTORIS muscle creatine kinase implant system forbicompartmental knee resurfacing, which also received FDA approval in

2008. MAKO is conducting initial studies of using the RIO system to

prepare the acetabulum for hip replacements and is planning a commer-cial rollout in the second half of 2011. As ofSeptember, 2010, there were

54 RIO systems in use in the United States.38

MAZOR SpineAssistMAZOR Robotics developed the SpineAssist due to high rates of spinal

surgery pedicle screw misplacement that was more pronounced withsevere deformities such as scoliosis. The rates of misplacement decreasedwith percutaneous fluoroscopic guidance and CT-guidance but result in a

considerable increase in radiation exposure. Another approach was to use

computer assisted surgery and it has improved screw placement, but it canbe difficult to use and is highly dependent on registration with a tracking

camera that can be negatively affected by numerous factors such as

camera angle and environment. As a result, MAZOR developed the

SpineAssist robotic system that addresses these registration issues bybeing physically mounted onto bony landmarks and then registered withintraoperative fluoroscopic images. Once registered, the six degree of

freedom manipulator has a drill guide as an end-effector and can be

programmed to position its manipulator to provide trajectories per thepreoperative plan for vertebroplasties, biopsies, excisions, and other



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procedures directed around the spine from a posterior approach (personal

communication from Mazor Robotics).41

Preoperatively the patient receives a CT scan per the SpineAssistprotocol with parallel slices 0.41.0 mm apart. The SpineAssist software

generates a three-dimensional model that the surgeon can use to planoptimal implant dimensions, (pedicle or translaminar facet screws)

starting position, and trajectory. Immediately prior to the procedure, both

the SpineAssist robot and fluoroscope need to be calibrated which can be

completed within 10 minutes. The robot is calibrated by placing it on amount with three holes and then positioning the drill guide towards the

holes with a K-wire, resulting in a system with an overall maximum error(after accounting for errors from CT, fluoroscopy, registration, and

others) of 1 mm from the preoperative plan. The fluoroscope is calibratedby placing a fiducial array with specifically arranged metal beads on the

image intensifier and then taking an anteroposterior (AP) and lateral x-ray

with no objects. These two blank pictures account for local magnetic field

distortions and calibrate the images. The patient can then be brought inand positioned for the procedure. Depending on the levels that will be

operated on, the robot can be rigidly attached to the patient by severalmounts: a spinous process clamp mount, a bed-mount or Hover-T mount

(Fig 5). For the clamp mount, a single spinous process is exposed and theclamp is physically attached to it, as a platform for the robot which

FIG 5.MAZOR SpineAssist robot mounted on the patients spine with guide attached. A surgeon ispassing a tool through the guide toward the desired target with appropriate trajectory. (Courtesy ofMAZOR Robotics, Inc, Norcross, GA).



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connects it directly and rigidly to the patients skeleton. From thatposition, the robot can guide implant placement from one vertebra above

to one below. The bed mount and bilateral bed mount are attached directlyto the OR table with a horizontal bar running across the patients lowerback and at the midline a longitudinal bar connects to it and lies above the

patients spine. At its cephalad tip a 2.5 mm k-wire is attached to a single

spinous process above the vertebras which are operated on. The Hover-Tframe can access many more levels, and requires attachment to one

spinous process with a K-wire and the posterior superior iliac spines with

Steinmann pins, thus, forming an upside down T on the patients backwith central longitudinal bar in alignment with the spine and the

horizontal bar attached to the pelvis. Next the system is registered bytaking 2 x-rays: AP and oblique of the target levels with the fiducial array

connected to the mount. Only 2 images are needed to register the

SpineAssist system (personal communication from Mazor Robotics).41

In order to access the different parts of the spine, the robot has

different attachment points on each mount (three for the spinousprocess mount and nineteen with the Hover-T frame), three different

drill guide lengths, and two extension bridges. The software can beused in conjunction with the preoperative plan and informs the

surgeon about which position, drill guide, and if an extension bridge

will be needed to place the implant. Once the surgeon positions therobot with appropriate guides and extension bridges, the robot moves

the guide to aim at the targeted entry point with the appropriate

trajectory. This system can be used for both percutaneous and openprocedures. For percutaneous approaches, the drill bit is guided to the

bone with a stab incision and blunt dissection, and a starting hole is

created through which a K-wire is passed to the vertebral body (in thecase of pedicle screws). Over the K-wire a screw hole is drilled, and

the walls of the pedicle are tested with a probe to ensure the side wallsare not breached. The preoperatively planned screw can be implanted

into this prepared hole, and this procedure is repeated for all

subsequent screws (personal communication from Mazor Robotics).41

The SpineAssist received initial FDA clearance in 2004 for usethroughout the spine and MAZOR is currently seeking approval for

applications in brain surgery. There are 25 hospitals in Israel, Germany,Switzerland, Russia, Netherlands and the US where SpineAssist is inregular use.42 To date it has been used in more than 2,000 spinal surgeries

around the world. In June 2011, Mazor Robotics launched a new

generation of SpineAssist named Renaissance that is capable of perform-ing osteotomies, transfacet and translaminar-facet implant placements,



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and the spinal procedures that SpineAssist is capable of performing.Renaissance has a new design and interface that has received FDA

clearance and CE-mark. The proposed advantages of the system arereduced patient radiation exposure for preoperative CT scans by up to50% together with other safety improvements.43

ROBODOCROBODOCs development was discussed above in the history section,

and since then improvements to the system have been made to reduce the

number of fiducials needed to 2: speed the milling process, and modify

cutting paths to decrease invasiveness (Fig 6).

44

The commercializationof the ROBODOC system has only been international in Europe, Japan,

Korea, and India, where the robot has been used for more than 24,000joint replacements. It received FDA approval in 2008. Integrated Surgical

Systems was responsible for the early business endeavors, but currentlythe system is being sold by ROBODOC, a Curexo Technology Com-

pany.19

AcrobotThe original Acrobot has been updated to be smaller and cheaper and is

being produced with the name Acrobot Sculptor. Other changes include

the addition of a navigation arm that tracks the knee without rigid fixationof the limb. This navigation arm can follow the knee as it moves, which

makes it easier for the surgeon to assess knee range of motion and laxity

during the procedure. Another feature is the addition of a passiveorientation device that lets the cutter end-effector be oriented for better

access while not changing the tip position. This entire system is now

mounted on a trolley.45 The Acrobot Sculptor is produced by the AcrobotCompany Limited and its use is being targeted for UKAs because of the

time-consuming nature of doing the bony resections needed for a TKA.45

Stanmore Implants Limited recently acquired the Acrobot Company

Limited (personal communication from Professor Davies). This system isnot approved in either Europe or the United States, but is in clinical trials

to gain European approval.21

Endoassist/FreeHandEndoassist was first developed by Armstrong Healthcare Ltd to serve as

a robotic laparoscopic camera holder. They wanted to address the issues

of shortage of health care personnel and difficulty of human assistants in

positioning the camera to the surgeons preferences. The key differencesbetween it and the AESOP robot are that it was freestanding and had a



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head-mounted control system.46 Because it is a freestanding robot, it must

be calibrated to the point where the laparoscope enters the patient body.If the position of the operating room table is moved relative to the robot

or if the laparoscope entry site is changed, it takes 1 to 2 minutes to

recalibrate the system.47 The surgeons head movements control the

robot. An infrared sensor mounted on top of the laparoscope monitordetects movements of the infrared emitter attached to the surgeons head.The direction that is recognized by the sensor is displayed above the

monitor, and the surgeon controls the duration of movement by pressing

the foot pedal. To zoom in and out, the surgeon switches modes bytapping the foot pedal and moves his head down or up, respectively.46

FIG 6. Current ROBODOC surgical system for preparing femoral cavity for total hip replacement/arthroplasty. (Courtesy of ROBODOC, a Curexo Technology Company, Fremont, CA.)



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In the early 2000s when both systems were on the market, the AESOPand EndoAssist systems were directly compared in 2 studies. One in vitro

study comparing their use in various tasks found that using EndoAssistresulted in faster times. This was attributed to issues with under- andovershooting with AESOP and inaccuracies with the voice control.48

Another study compared their use in laparoscopic radical prostatectomies

and found that AESOP had faster setup time by 3.3 minutes andEndoAssist was faster with 1 of the operative steps by 10 minutes. No

statistical difference was found in the remaining 11 operative steps.However, these results cannot be compared to the prior study because

AESOP was controlled in this study by an assistant with the hand-control

because of the poor voice recognition. One of the purported advantages ofthese robots is that the surgeon is in control of the camera, but in this

study AESOP was controlled by the assistant while EndoAssist was

controlled by the surgeon.47

Endoassist was approved by the FDA,25 and production of the robot was

transferred to Prosurgics Ltd, which replaced EndoAssist with theFreeHand system.49 FreeHand received FDA approval in 2009 and

currently is marketed by FreeHand Surgical PLC.49 The control systemremains the same as for EndoAssist, but it is not a freestanding robot. It

can be mounted anywhere on the operating table rails depending on the

needs of the laparoscopic procedure (Fig 7).50

da Vinci Surgical SystemThe development of the da Vinci Surgical System is discussed above in

the History section. It is manufactured by Intuitive Surgical. This system

is a telesurgery system composed of 3 components: a surgeons computer

console, a video cart, and a robotic tower (Fig 8). The surgeons computerconsole is where the surgeon sits and can look into the binoculars to

perceive a 3Dview of the surgical field with stereoscopic 0, 30, or 45endoscopes.23 More recent versions of the robot (the da Vinci S HD and

da Vinci Si models) offer high-definition 3D vision. The surgeon controlsthe robot with the masters, which read the surgeons hand movements

more than1300 times per second and converts them to robotic instrument

movement.3 In addition, the surgeon can change the scaling of the masters

to 1:1, 3:1, or 5:1. Through the masters some haptic feedback is deliveredbut the level of sensation is dependent on the position of the instrumentsand is most consistent when the instruments hit rigid bodies. The surgeon

also has foot controls for energy instruments, camera position, clutch for

the masters, and switching robotic arm control.3,23

The video cart is the storage center for the light sources, camera control



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boxes, insufflators, and other equipment. At the top of the cart is a

touch-screen monitor that can be used to adjust the instrument settings (ie,

brightness) and for local teleproctoring. The original da Vinci system hada robotic tower with 3 robotic arms (1 camera and 2 instrument), and in

FIG 7.FreeHand robotic laparoscopic camera holder mounted on the operating table. (Courtesy ofFreeHand Surgical Plc, Bracknell, UK.) (Color version of figure is available online.)

FIG 8.Intuitive Surgical da Vinci Si Surgical System with surgeons console on the left, robotic towerin the middle, and video cart on the right. The individual standing at the video cart is demonstratingthe teleproctoring system and has drawn a circle on the touch screen monitor. (Courtesy of Intuitive

Surgical, Inc, Sunnyvale, CA.)



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2002 the FDA approved a new system with 4 arms (1 camera and 3

instrument). The third instrument arm can be used as a retractor that

stays locked in its last position whenever the surgeon is controlling theother 2 instruments. Modular reusable end-effectors, which can be

used for 10 operations, can be switched throughout a surgery by the

patient-side surgeon.23 The da Vinci system received expanded FDA

approval in December 2009 for use in transoral otolaryngology

procedures.51 Currently, there are more than 1600 Da Vinci systems in

use worldwide.52

CardioARMCardioARM was first conceived by cardiac surgeon Marco Zenati, MD,Howie Choset, PhD, and Alon Wolf, PhD, through a collaboration

between the University of Pittsburgh and Carnegie-Mellon University.

These 3 went on to found Innovention Technologies in 2005, later

renamed as Cardiorobotics, to further develop and commercialize their

system.53 The problem they were seeking to address was the difficulty

that rigid shaft instruments had in reaching the posterior side of the heart

for epicardial interventions.54

Their system was based on a snake-likedesign of sequential rigid cylindrical links that allows it to bend at various

joints along its length; its distinction from simple endoscopes is that it can

maintain its prior shape as it moves forward and backward (Fig 9). Thus,

this system is able to go around anatomical obstacles without risk of

inadvertently hitting them on advancement. For cardiac applications, this

system is designed to be inserted through a subxiphoid port and then

use its maneuverability to access any part of the epicardium. Cardio-

ARM works using cables, controlled by motors outside the patient,which run through all cylindrical links to control their motion. The

distal end is 10 mm in diameter and has a fiber optic endoscope that

displays vision from the distal tip on a monitor and also has a working

port through which off-the-shelf 8-French catheter devices can be used

for interventions.54,55 Newer versions allow the simultaneous use of

multiple tools, such as an ablation catheter with an irrigation/suction

device.56 The surgeon controls the distal link with 2 d.f. via a joystick,

while another button controls the amount of insertion. As the robot isadvanced, it follows the prior path and at the distal end it follows the

direction that the tip is facing. As a safety mechanism, the system can

become limp for easy removal.54

The cardiac applications that the system is being considered for are

ablation, injection (for stem cell or other therapeutics), mapping,



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pacemaker lead placement, biopsy, and ligation of the left atrial

appendage. For ablation, endocardial catheter techniques traditionally

have been predominantly used because of the invasiveness of tradi-

tional epicardial approaches that require a sternotomy or thoracotomy.

Using a simpler subxiphoid approach instead, Cardiorobotics ishoping to open up alternative and possibly more efficacious treatment

options for cardiac patients.54 Reports of using the system in multiple

live porcine and cadaveric studies have reported that it can be used for

all these cardiac applications.54-56 Published human clinical trials are

still pending, and Cardiorobotics is hoping to commercialize their

system by 2012.53

Cardiorobotics is also exploring potential uses of the CardioARM

system for gastrointestinal and intravascular procedures. The systemcould be adapted for natural orifice translumenal endoscopic surgery

(NOTES) via transoral or transrectal access to the small intestine or other

abdominal organs. For intravascular procedures, the CardioARM system

could provide more controlled maneuvering for percutaneous coronary

interventions.54

FIG 9.CardioARM robot demonstrating its snake-like design and flexibility at each of its numerous

joints. (Reprinted from Ota T, Degani A, Schwartzman D, et al. A highly articulated robotic surgicalsystem for minimally invasive surgery. Ann Thorac Surg 2009;87:1253-6.)



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SenseiHansen developed the Sensei master-slave robotic system to control

catheters with a focus on use in cardiac electrophysiology procedures,such as ablation. Currently, these procedures require precise control of the

catheter tip to deliver appropriate ablation to the cardiac conduction

pathways while exposing cardiac electrophysiologists to high levels of

fluoroscopic radiation needed for visualization. The Sensei system was

designed to address both of these issues by providing physicians better

control and decrease their radiation exposure.

The slave is a robotic arm positioned at the foot of the procedure table

and controlled via pull wires through an external and internal sheath thatcan carry traditional ablation catheters. The external sheath has 1 pull

wire that allows it to be deflected, rotated, and inserted/withdrawn. The

internal sheath has more control with a pull wire in each quadrant

providing it the capability to move 360 and also be inserted or

withdrawn. Ablation catheters are positioned just past the internal sheath

and the physician can control its motion via the masters 3D joystick. The

physician can view the procedure with traditional fluoroscopic images

and can also integrate real-time electroanatomic mapping (EAM) and 3DCT imaging with the robotic catheter positioning. A preoperative 3D CT

image of the heart can be registered with EAM information. This

integrated image can be registered with the robot in 5 minutes as the

robotic catheter advances retrograde through the aorta as it maps the

aortas endoluminal surface. An initial registration is developed from this

information and can be refined by having the catheter collect data in the

left atrium. The integrated image with EAM, 3D CT, and robotic catheter

positioning is presented in an integrated fashion to the physician who canchange perspectives. The joystick moves the catheter with respect to the

view that the physician is using (Fig 10), meaning that regardless of

which perspective the physician is viewing the heart, moving the joystick

to the right results in the catheter moving to the right on the image.

Similar to the da Vinci Surgical System, the controls can also be scaled

with 1:1 or 4:1 ratios. Since the masters do not provide haptic feedback

through the controls, the IntelliSense system detects forces at the catheter

tip and uses synesthesia with a visual warning when the tip forces areconcerning for risk of perforation.57

NiobeStereotaxis developed the Niobe magnetic guidance system for cathe-

ters because of the difficulties in accurately directing manually guided



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catheters for cardiac electrophysiology, interventional cardiology, and

interventional neuroradiology.58,59 Based on prior work using magneticcatheter guidance since 1951, the Niobe system addresses this problem

using 2 permanent magnets to similarly guide a catheter. These 2 magnetsare each kept in a casing located on both sides of the patients procedure

table, and they are used to create a 15-cm spherical 0.08 T magnetic field

centered on the heart or other target organ (Fig 11). A computer system

is able to manipulate themagnets to create a magnetic field vector in anydirection in 3D space.58 Depending on the amount of vector directionalchange, the time to change the field can take 5-20 seconds.60 Wires with

magnets at their tip will align themselves in line with the magnetic field,

but will not be advanced or withdrawn due to the magnetic field.Magnetic wires of varying stiffness and other properties are producedto

provide the physician flexibility in performing the desired procedure.58

The physician controls the direction of the magnetic field through the

control software to direct the wire collinearly with the target and then canadvance the wire toward it. Advancing/withdrawing the wire can bemanually controlled or performed with an additional robotic wire ad-

vancer (Cardiodrive Catheter Advancement System).61 In the case ofmanual control, a sterile touch-screen magnetic field control system can

be placed by the physician as he/she performs the procedure. If a robotic

FIG 10.Hansen Sensei robots physicians console with the physician directing the catheter with thejoystick below the monitors. (Courtesy of Hansen Medical, Mountain View, CA.)



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advancer is used, the wire and magnetic field controls can be used on anintegrated control station located remotely from the procedure table. In

this case, the physician is protected from radiation exposure during theprocedure and can track the position of the wire on the imaging since the

robot can measure the degree of advancement.58

The magnetic field control software can integrate live fluoroscopyimages, biplane and rotational angiography, CT, and EAM.58 The

software can also construct 3D coronary vessel models based on 2angiographic images that are at least 30 apart.62 These images are

registered to the patient using fluoroscopic landmarks, including spinous

processes and the catheter. Since the heart is continuously beating, the

software can gate the imaging to the electrocardiograms phase. Thephysician-software interface (Navigant Software User Interface) is criti-

cal for the physician to use all the available imaging to determine thesubsequent 3D magnetic field direction.61 Stereotaxis has developed both

2D and 3D view interfaces to simplify drawing magnetic field vectors. Inaddition, endoluminal, bulls-eye views, and various other multiplanar

reconstructed cross-sections can be usedto simplify navigating through

lumens narrowed by atherosclerosis.58,62 Magnetic field vectors appro-

priateness can be verified bychecking the vectors on the orthogonal viewspresented by the software.60 Another tool used to simplify navigation isthe inclusion of preset magnetic fields based on expected directions for

the coronary vasculature based on averages from numerous patients. The

physician is given the ability to create their own frequently used presetfields as well.58

FIG 11. Stereotaxis Niobe system in the procedure room with both magnet systems adjacent to thetable and a fluoroscopy unit at the head of the table. The physicians control system is accessiblethrough the touch screen monitors mounted from the ceiling. (Courtesy of Stereotaxis, St. Louis, MO.)



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One problem that was noted in early studies was that the use of a strong

external magnetic field can distort electrocardiograms used for electro-

physiology procedures. However, they reported that analysis of therhythm or morphologies of P-wave and QRS complexes were not

affected, and that intracardiac readings were qualitatively not affected.59

Stereotaxis is looking to apply the more than 150 globally available

Niobe systems63 for improved accuracy in cardiac electrophysiology

ablation, percutaneous coronary interventions in difficult anatomy andchronic total occlusions, and possibly in the future for stem cell

implantation.62 Niobe has been FDA approved for cardiac electrophysi-

ology and interventional neuroradiology since 2000 and interventional

cardiology since 2003.58

Clinical Outcomes

NeurosurgeryNeuromate. No studies directly comparing traditional stereotactic

biopsy techniques with robotic techniques have been published. Multiple

case series have been published reporting on the accuracy of the

Neuromate in the literature, and the ones that will be discussed involvethe frameless Neuromate technique.28,30,64 One series looking at masslesion biopsies reported that 18 of 19 were diagnostic, while the

nondiagnostic biopsy was from the abnormal region as indicated by

postoperative imaging.28 Neuromate has been used for transcerebellarbiopsies in the delicate brainstem where 13 of 15 were diagnostic, and 1

of the remaining 2 was diagnostic on the second procedure. Despite the

high risk of operating in the brainstem, there was no operativ

Documents

2011 - Karthikeyan Ponnusamy - ClinicalOutcomesWithRoboticSurgery[Retrieved-2014!05!25]