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Introduction
Advances in spine surgery during the past 10 years have
been nothing short of brilliant! In fact, anyone who undergoes
spine surgery today will benefit from new technologies that
have improved imaging, anesthesia, surgical technique and
instrumentation.
One of the greatest advances has been the emergence of image-guided
surgery. Image-guided surgery enables spine surgeons to
see and navigate through the patient's anatomy three-dimensionally
(3D) in real time before and during surgery!
This remarkable development is the result of a combination
of futuristic technologies including computers, sophisticated
software, specialized surgical tools, and precision position-measurement
systems. The use of such technologies results in greater
surgical accuracy and increased ability to apply minimally
invasive surgical techniques. Consequently, the patient
outcome is better!
Image-Guided Spine Surgery: Brief History
To appreciate where we are today - technologically speaking,
we have to take a couple of 'historical' steps backward.
In fact, almost 100 years back when x-rays were first discovered.
You could say that x-rays were the most basic form of image-guided
surgery!
Traditionally, a surgeon examined the patient's x-rays and
relied on his wealth of knowledge and skill to perform the
procedure. The surgeon was limited by 1) what he could see
on the x-ray, and 2) the anatomy exposed by surgically opening
the patient.
This was hardly image-guided surgery, as it is known today.
This might be compared to driving a car. You have been trained
how to drive safely (knowledge, skill), you know the neighborhood
(anatomy), but you don't actually know what is ahead until
you get there (tumor). A map (x-ray) is helpful, but cannot
reveal what is ahead in 'real time three-dimensionally'.
Progress really started to be made when computers came on
the scene as well as the development of ways to measure
the location of an object very precisely. An example of
this is Global Positioning Systems (GPS), originally designed
for military use. These technologies as well as Computed
Tomography (CT Scanning) and Magnetic Resonance Imaging
(MRI) began to combine forces in the 1970's and 1980's.
Another step forward was the development of 'frameless stereotaxy'.
Stereotaxy means a stationary device (frame) assists in
the precise guidance of a surgical instrument (taxy or tactic).
The first forms involved attaching a frame to a patient's
head, taking x-rays (map of the patient's anatomy), and
using the frame as a guidance system to find the location
within the brain. At that time it was called 'framed stereotaxy'.
Bringing it All Together
By the early 1990's scientists, surgeons and other experts
were beginning to draw together the technologies described
above to develop comprehensive frameless image-guidance
systems for surgery. The forerunner in this breakthrough
and a leader in the field today is the StealthStation™.
Let's take a look at the StealthStation™
to better understand how image-guidance helps surgeons.
The components
of the StealthStation™
include a high-performance computer, sophisticated software,
touch-screen monitor, a camera to recognize light emitting
diodes (LEDs), and several specialized instruments fitted
with LEDs. LED technology is similar to your television
remote control. When you press a button to change the channel,
a small red light communicates your request to the television
and the channel changes.
Several days before surgery, the necessary images (CT Scans
and/or MRIs) of the patient's spinal anatomy are prepared.
The images are then 'downloaded' into the StealthStation™
computer and the system creates three-dimensional images
of the spinal anatomy. The 3D images can be rotated, enlarged,
flipped, angled, or manipulated in a variety of other important
ways. This allows the surgeon to accurately pre-plan the
surgical procedure including determining the type and size
of instrumentation (e.g. screws) and implant placement and
trajectory. Such pre-planning is helpful to ensure a successful
surgical outcome, especially for patients with spinal deformity
whose anatomy often does not match that in a textbook.
During surgery the instruments communicate with the computer
and surgeon in real time. This means the spine surgeon can
watch on a computer monitor as he precisely operates on
the spine. Looking at the computer monitor, the surgeon
can see the position of the instrument as it relates to
portions of the patient's anatomy that are beneath the surface
of skin, hidden from the surgeon's direct view.
Additionally,
the advent of image-guidance has enabled greater use of
minimally invasive techniques. For example, the StealthStation™
can help a surgeon see 'through' the skin; therefore, the
surgeon does not need to make a large incision just to expose
and see the anatomy underneath the skin.
Technically Speaking - This is How it Works
The first and most important step is 'registration'. A special
probe fitted with LEDs is used to teach the computer the
exact location of the patient. The camera tracks the LEDs
emitted by the probe as the surgeon touches different points
on the patient's spinal anatomy. This builds a one-to-one
relationship between the computer and patient.
During surgery, the patient's spinal anatomy moves, such
as during breathing. The 'connection' between patient and
computer established during registration enables the StealthStation™
to automatically update images each time the anatomy moves!
Throughout the surgery, the computer can generate images
of the patient's anatomy as it relates to the surgeon's
instrument. All this power is at the surgeon's fingertips
using a touch-screen or a mouse!
Conclusion
Image-guided surgery systems are valuable for spine surgeons
for pre-operative planning, navigating complex spinal anatomy,
surgical precision, injury prevention and patient safety.
Systems such as the StealthStation™
have been used for thousands of patients in the United States
and Europe with successful results proven by a wealth of
data.
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