Harry Dankowicz and Don Leo. Photo by Michael Kiernan.
Two-dimensional radiographs such as this one show spinal deformity in a scoliotic patient
in various positions and coarse spinal geometry for three-dimensional
reconstruction.
The
software environment makes possible three-dimensional evaluation of
computer-generated three-dimensional reconstruction of the vertebral
column from digital radiographs.
Software developed by researchers with the Virginia Tech-Wake Forest
University School of Biomedical Engineering and Sciences creates
three-dimensional images of the spine that can be manipulated for detailed
examination. The medical team can then communicate with machinery
that will bend a titanium rod to the surgeon's specifications.
A rod, with the precise connection points and shape to correct the curvature of
the spine, is ready before surgery begins. Photo by Michael Kiernan.
A teenager lies unconscious on an operating table, her spinal column
exposed as a surgeon struggles to bend a titanium rod with a hand-held
tool. The rod must be shaped into an angle that will help correct the
patient's severe spinal deformity. After the surgeon wrestles the rod
into an approximate angle, he bolts it to the vertebrae along a section
of the spine.
Corrective surgery for scoliosis — a descriptive term for abnormal curvature
of the spine — has advanced through the past few decades, with increases
in the success rate and decreases in the time and discomfort of recovery.
Surgery can reduce the magnitude of the spinal curvature, limit progression
of the problem, and help shape a well-balanced spine in scoliosis sufferers.
However, certain aspects of the procedure could use a technological boost.
"Shaping and affixing the rods to the patient's spine during scoliosis
surgery can take several hours. The process of shaping rods with a hand
tool is tiring to the surgeon and potentially increases the risk to the
patient," says Harry Dankowicz, an associate professor of engineering
science and mechanics at Virginia Tech. He is leading a collaborative
effort to develop what could become one of the next advancements in the
surgical treatment of scoliosis.
Working with Dankowicz are Don Leo, a professor of mechanical engineering
at Virginia Tech, and Dr. Jeffrey Shilt, an associate professor of pediatric
orthopaedic surgery at the Wake Forest University School of Medicine.
Dankowicz, Leo, and Shilt, all affiliated with the Virginia Tech-Wake
Forest University School of Biomedical Engineering and Sciences, have
created hardware and software that can help surgeons plan and carry out
procedures aimed at correcting each patient's particular spinal deformity.
Scoliosis affects between 2 and 3 percent of the population - an estimated
6 million people in the United States, according to the National Scoliosis
Foundation. The condition usually is idiopathic (the result of unknown
causes) and typically develops during childhood. In 2003, the Virginia
General Assembly passed legislation requiring scoliosis screening in public
schools for grades five through 10. Although the onset of scoliosis affects
about the same number of male and female children, teenage girls are several
times more likely to develop severe curvature of the spine.
Many sufferers are able to forego medical treatments, but scoliosis can
progress to severe spinal deformity, accompanied by chronic pain, limited
mobility, and even difficulty breathing. Each year, the foundation notes,
about 30,000 children are fitted with braces as a corrective measure and
another 38,000 undergo spinal fusion surgery.
The idea for the Virginia Tech-Wake Forest collaboration was launched
in December 2001 during the early days of the establishment of the joint
School of Biomedical Engineering and Sciences, when Dankowicz and Leo
visited Shilt in Wake Forest's Department of Orthopaedic Surgery.
During a discussion of scoliosis treatments, Shilt
described the difficulties in performing corrective surgery and the need
for new technology.
Dankowicz and Leo returned to Blacksburg with a
goal in mind.
Currently, in preparing to operate on a patient with idiopathic scoliosis,
a surgeon inspects two-dimensional X-rays of the spine and then refers
to a classification scheme that helps identify curvature patterns and
determine surgical techniques. The surgeon may be aided by software that
helps measure the two-dimensional curvatures of the patient's spine.
With the objective of advancing the computer-aided technology associated
with scoliosis surgery, Dankowicz, in consultation with Shilt, developed
software that uses two-dimensional X-rays to create three-dimensional
images of a patient's spine. This software is designed to aid a surgeon
in a number of ways.
First, the software's three-dimensional images can be manipulated and
rotated to provide complete and detailed views of a patient's spine, enabling
the surgeon to thoroughly analyze the spinal deformity before surgery
begins.
The software also can search the most sophisticated and commonly used
curvature classification scheme - the Lenke method - and determine the
classification that most precisely matches a patient's particular spinal
deformity. A Lenke method diagnosis, which is based on criteria from all
known curvature types, enables a surgeon to locate the areas of the spine
where rods should be attached and to determine how the rods should be
shaped to most successfully correct the curvature. In addition to finding
a Lenke classification to match a patient's scoliosis, the software Dankowicz
and Shilt created can evaluate the statistical reliability of the classification.
Finally, the software can communicate computer-aided-design information
to a hardware tool that will bend titanium rods to precise specifications
indicated by the Lenke classification and the surgeon's analysis of a
patient's spinal curvature. An initial prototype of the hardware tool
was developed over a period of two years by students advised by Leo and
Dankowicz in the mechanical engineering senior design course. Hosted by
Shilt, several of the students attended spinal fusion surgeries at the
Wake Forest University Baptist Medical Center.
The researchers are now working to perfect the software and hardware
system. Second-generation development and integration of the hardware
tool with a software-based control architecture is being pursued by Dankowicz
and his research group at Virginia Tech. Shilt is testing the software's
effectiveness as a modeling and classification tool from a surgeon's point
of view. "This project is an excellent example of how Virginia Tech
and Wake Forest can work together to advance research goals in biomedical
engineering," says Leo. "It also involved faculty members and
students, who were able to learn some valuable design skills." In
addition to collaborating on the project, Dankowicz and Shilt served together
on the graduate committee for Dean Entrekin, a master's degree student
who was part of the research team. The researchers have provisional patents
on both the software and the hardware tool through Virginia Tech Intellectual
Properties Inc. and are exploring options for licensing of the inventions.
"This proposed software and hardware system could significantly
decrease the time and physical effort required of the surgeon in designing
and shaping the rods used in spinal fusion," Dankowicz says. "Reducing
the time required for surgery could reduce the exposure of a patient to
potential infections."
Dankowicz notes another equally important advantage of the new system.
"The increased accuracy of the computer-aided-design, as compared
to manually shaped rods used as spinal implants, is expected to improve
the likelihood of a successful outcome of spinal fusion surgery."
Dankowicz, who recently received a coveted National Science Foundation
(NSF) Presidential Early Career Award for Scientists and Engineers for
his research in the instability of dynamic systems, has for several years
studied methods of preventing fall-related injuries. Among his goals is
the design of prosthetic and orthotic devices that could reduce instability
for people, such as the elderly, who are at risk of injury from falls.
He also has worked with researchers in the Virginia-Maryland Regional
College of Veterinary Medicine on an exoskeletal device for equine limb
disorders and injuries.
For Leo, the scoliosis treatment technology was the first opportunity
to work in the area of medical devices, but his research in dynamics and
control of active material systems has attracted significant grants, including
an NSF Faculty Early Career Development Program Award. Currently, Leo
is leading a multi-university team of researchers in development of a
new class of materials, using plant protein structures in an attempt to
mimic biological systems.
