Robots in the Operating Room
by Kevin L. Ropp

Imagine you're having a hip replacement, a fairly common
operation, especially if you're an older American. As you're
wheeled into the operating room, you notice the nurses and
anesthetist preparing for your surgery.
But wait, someone's missing. Your surgeon.
You look around the room and finally spot the surgeon, off
in the corner keying information into a computer terminal.
And there, next to the doctor and computer is a 500-pound,
7-foot-high, jointed steel arm, with a tiny drill attached to one
end.
It's Robodoc. And it's going to assist in your surgery. During
the procedure it will drill the hole in your thigh bone (femur)
that will hold the anchor of your new hip joint.

While robots have long been used to assist surgeons during
operations, the devices may soon take a more active role in
surgical procedures such as hip replacements, removal of
brain tumors, prostate surgery, and laparoscopy.
But, while medical robots may make some surgical
procedures easier or help the surgeon perform an operation
more precisely, the Food and Drug Administration, which
regulates these new devices, has several concerns.
One concern is software. Today's robotics devices typically
have a computer software component that controls the
moving, mechanical parts of the device as it acts on
something in its environment.
FDA reviewers evaluate the software components of such
devices because the software is "command central" for the
device's operation.
When evaluating the devices, FDA looks to see if the
company is following good software engineering practices in
writing and designing the software. These practices often
include establishing device requirements, writing good
specifications, evaluating the software and device, analyzing
the device's potential hazards, and implementing controls that
specifically address those hazards. Other concerns include the
safety and effectiveness of the hardware component of the
device.

Robodoc
Robotics devices being developed today take computer
technology to a new level of sophistication.
One of the most ambitious projects, and probably the best
known in the United States, is Robodoc--a modified
industrial robot that performs certain aspects of a surgical
procedure. It was created by Howard Paul, D.V.M., a
veterinary surgeon, and William Bargar, M.D., an orthopedic
surgeon. (Paul died of leukemia Feb. 10, 1993.)
The device made history and headlines late last year when it
drilled a hole in a femur to hold a patient's hip implant in
place without cement.
Ten robot-assisted human hip replacements using Robodoc
were performed at Sutter General Hospital, Sacramento,
Calif., under an investigational device exemption (IDE)
approved by FDA Oct. 9, 1992. The first was done Nov. 7,
1992, on a 64-year-old man suffering from  osteoarthritis, the
condition most commonly necessitating hip replacement. The
surgery took nearly six hours, about double the usual time for
more traditional hip replacement procedures.
The last, performed Feb. 11, 1993, took two hours and 40
minutes--about the same amount of time it takes a surgeon to
perform the operation using traditional tools.
Before approving the IDE, FDA paid particular attention to
the software and back-up safety systems.
"When you talk about things that are computer-controlled or
automated, people tend to believe that if it's automatic it's
better," says FDA biomedical engineer Theodore Stevens.
"But, like any computer, [Robodoc] only does what you tell it
to do.
"It takes sophisticated software to run a robot or milling
machine. As a result, there's some really serious software
questions, especially for a device that actually operates on
humans."
FDA uses two criteria to classify all medical devices. The first
is whether a device is equivalent to an existing device that
has been on the market since before May 28, 1976--the day
FDA began implementing the Medical Device Amendments
to the Food, Drug, and Cosmetic Act. If it is equivalent, the
new device is classified the same as the existing device.
If a device does not meet the first criteria, FDA evaluates it
according to a second criterion: It is considered a class III
device that must undergo clinical testing and have FDA
approval before it can be sold. Robodoc falls into this
classification.
Because they may pose a significant risk to the patient's
health, all new class III devices must be evaluated for safety
and effectiveness.
Robodoc, for example, cuts the patient without direct human
control of the cutting tool, according to Mark Melkerson,
acting chief of the orthopedic devices branch in the Center
for Devices and Radiological Health's office of device
evaluation.
As a result, there has to be a very well-controlled software
development program and there have to be physical limits on
how much the device's cutting tool can move. In fact, there
are built-in safeguards to make sure the device drills only the
femur and doesn't cut into soft tissue, Stevens adds.
Robodoc was born out of Paul's and Bargar's desire and
attempts to improve the fit of implants in the femur in
cementless total hip replacements. About one-third of the
250,000 hip replacements performed in the United States
each year are cementless.
Unlike procedures that use cementing materials to fix the
implant in place, porous cementless hip implants, introduced
in the mid-1970s, are made with porous coatings that allow
tissue to grow directly to the implant, holding it firmly in
place.
"Our hypothesis was that if we could do the surgery more
precisely, then the outcome would be better," Bargar says.
FDA's Stevens explains that with traditional replacements,
free space between the implant and the bone may allow the
implant to move, which could be painful. The implant also
might take more time to "fix" rigidly or might not "fix" at all.
Theoretically, Robodoc makes possible very close physical
contact between the bone and the implant stem, reducing
pain and improving the "fix" of the replacement.
In planning for a traditional hip replacement, the surgeon
takes a picture of the patient's femur using computed
tomography (CT) or  magnetic resonance imaging (MRI).
The surgeon then overlays these pictures with acetate
templates of implants until a close match is found for that
particular patient.
During surgery, the doctor removes both the hip socket and
the top of the femur. Using a hammer and broach (a
cylindrical cutting tool with teeth on the surface), the surgeon
chisels an 8- to 10-inch-deep hole down the length of the
bone--an imprecise method at best. The surgeon then
hammers the steel or titanium implant into place, attaches it
to the hip socket, and sews up the incision.
In preparing for robotics surgery, about a week before the
actual procedure the doctor places three small titanium pins
in the patient's femur. Robodoc will later use these as
markers to locate the precise point to begin drilling. Next,
three-dimensional pictures of the patient's femur are taken
using a CT scanner or MRI system.
These pictures are then fed into a computer along with other
patient data the doctor uses to select the best implant for
that patient. Using this information, along with already
loaded data that defines the specific size and shape of the
implant, the surgeon programs the robot to make specific
cuts in the patient's femur. These cuts mill out a cavity
matching the shape and size of the implant.
During surgery, the doctor removes the hip socket and top of
the femur, immobilizes the bone in a "fixator," aligns
Robodoc to the three pins, and, if all information and
alignment is correct, hits the "start" button, which tells the
robot to begin drilling.
Robodoc, using its high-speed drill, then cuts the hole down
the length of the femur. The resulting cavity almost exactly
matches the size and shape of the implant. The cavity
Robodoc creates is up to 10 times more precise than that
created by surgeons with hammers and broaches, according to
a report in the journal Clinical Orthopedics.
"The robot can cut with far greater accuracy than any human
hand. We looked at radiographs taken just before patients
left the hospital and, over the implant's surface, we didn't see
any gaps, unlike with hand tools," Bargar says.
Now that 10 surgeries are done, Bargar says, Integrated
Surgical Systems, the company formed to develop Robodoc,
plans to ask FDA for permission to conduct full-scale clinical
trials at five or six medical centers around the country,
including Shadyside Hospital in Pittsburgh and New England
Baptist Hospital in Boston. The results of the clinical trials
will be compared with results of surgeries using traditional
methods.

Brain Cancer Surgery
Robodoc isn't the only robot used in the operating room.
Neurosurgeon James Drake at the Hospital for Sick Children
in Toronto uses a robotics device to remove previously
inoperable brain tumors in seriously ill children, as well as in
epilepsy and vascular malformation surgeries.
He and the three other neurosurgeons on the hospital's staff
use the ISG Viewing Wand--an imaging computer and a
jointed arm with a probe attached to the end. The device,
currently under FDA review, "is calibrated like a robot but it
doesn't move under any of its own power," Drake says.
In preparing for surgery using the device, the doctor takes CT
scans or MRI images of the patient's brain. These images,
which  outline the tumor boundaries, are then fed into a
computer, which reformats the pictures into a "three-
dimensional picture that looks just like the patient," he says.
The robot arm holds the 5-inch to 10-inch probe. With the 3-
D pictures on a computer screen during the operation, the
surgeon directs the robot arm to slide the probe into the
patient's brain. The position of the arm in space is relayed to
the computer, which "shows you on the reconstructed images
[on the computer screen] exactly where you are in the brain.
"Without the ISG Viewing Wand, some of these kids would
not have been operated on or the surgery would not have
been as successful in removing tumors," Drake says.

Prostate and Abdominal Surgeries
Prostate surgery using robots is being tested in Great Britain
although this technology has not yet been tried in the United
States.
Brian Davies, senior lecturer in the Department of
Mechanical Engineering's Robotics Center at London's
Imperial College, is working with the Institute of Urology to
test a computer-driven robotics device that removes diseased
prostate glands.
It has a special-purpose framework consisting of a tiny ring
that rotates 360 degrees. The ring holds a small sliding
carriage that carries an endoscope (an instrument for viewing
inside a hollow organ) and cutter.
The entire system is attached to a thin, flexible catheter,
which is motorized and computer controlled.
"We preoperatively image the size of the gland using
transrectal [through the rectum] ultrasound and then program
into the computer control system the size of the gland,"
Davies says. The computer system automatically generates
the shape and sequence of cuts.
Watching the progress on a nearby video monitor, the
surgeon inserts the catheter with instruments into the
patient's penis until the computerized system reaches the
correct place.
At this point, the surgeon turns the operation over to the
robot, which performs the necessary preprogrammed cuts,
according to Davies.
So far, the procedure has been used on only five patients,
Davies says, and it's too early to draw any conclusions about
the device's safety.
In addition to the prostate device, the Robotics Center is
designing rehabilitative robots, as well as those to machine
the ends of bones for prosthetic implants in knee surgery.
Another area in which robotics may soon take on a role is
that of laparoscopy used in surgery.
To perform laparoscopy, the surgeon threads a fiber-optic
cable that holds a tiny video camera and cutting tool on the
end through a small incision in the patient's abdomen. The
surgeon monitors the operation by images on the monitor.
The video camera is usually operated by an assistant.
Though these procedures are less traumatic for the patient
than traditional surgery with its larger incisions, they are
more difficult for the surgeon.
Some U.S. companies are working on devices that would
make these procedures easier for the surgeon. For example,
IBM Corp. is currently developing a robot to move and
manipulate the tiny camera  and cutting tool. The camera
would be guided by the surgeon's voice.
While it may be some time before patients see something as
friendly as R2-D2, the famous "Star Wars" movie robot, in
the operating room, less dramatic-looking robots have begun
to assist surgeons with a good number of surgical procedures.
Kevin L. Ropp is a staff writer for FDA Consumer.
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