A team of engineers and pediatric orthopedic surgeons are using 3D
printing to help train surgeons and shorten surgeries for the most
common hip disorder found in children ages 9 to 16.
Shortening Surgery Times
In a recent study, researchers showed that allowing surgeons to prep on a
3D printed model of the patient’s hip joint cut by about 25 percent the
amount of time needed for surgery when compared to a control group.
The team, which includes bioengineers from the University of California
San Diego and physicians from Rady Children’s Hospital, detailed their
findings in a recent issue of the Journal of Children’s Orthopedics.
Dr. Vidyadhar Upasani, pediatric orthopedic surgeon at Rady Children’s and UC San Diego and the paper’s senior author, said:
“Being able to practice on these 3D models is crucial.”
In this study, Upasani operated on a total of 10 patients. For five of
the patients, he planned the surgeries using 3D printed models. He
didn’t use models to plan the other five. In addition, two other
surgeons operated on a different group of five patients without using
models. In the group where Upasani used 3D printed models, surgeries
were 38-45 minutes shorter compared with the two control groups. These
time savings would translate into at least $2700 in savings per surgery,
researchers said. By contrast, after the one-time cost of buying a 3D
printer for about $2200, physicians can make a model for each surgery
for about $10.
The results of the study were so positive that Rady Children’s
orthopedics department has acquired its own 3D printer, Upasani said.
“I’ve seen how beneficial 3D models are,” he said. “It’s now hard to
plan surgeries without them.”
Slipped capital femoral epiphysis is a condition that affects about 11 in 100,000 children in the United States every year.
In this condition, the head of the patient’s femur slips along the
bone’s growth plate, deforming it. The main goal of the surgery is to
sculpt the femur back into its normal shape and restore hip function.
This is difficult because during the surgery, the bone and its growth
plate are not directly visible. So the surgeons can’t visualize in 3D
how the growth plate is deformed. The condition is associated with
obesity and hormonal dysfunction and has become more common as obesity
increases among young people.
Traditionally, before the surgery, physicians study X-rays of the
surgery site taken from different angles, which they use to plan the
bone cuts. During surgery, an X-ray fluoroscopy beam also shines
periodically on the surgery site to help guide the physician. These
methods are time consuming and expose the child to radiation. In
addition, physicians don’t have a physical model to educate patients or
practice the surgery beforehand.
How the 3D Printed Models Were Made
In this study, two UC San Diego students, Jason Caffrey, pursuing a
Ph.D. in bioengineering, and Lillia Cherkasskiy, pursuing an M.D. and
conducting her Independent Studies Project, teamed up with Upasani,
bioengineering professor Robert Sah, and their colleagues. They used
commercially available software to process CT scans of the patients’
pelvis and create a computerized model of bone and growth plate for 3D
printing. The models allowed surgeons to practice and visualize the
surgery before they operated in the real world.
One of the biggest obstacles was getting the right texture for the 3D
prints, so that they mimic bone. If the texture was too thick, the model
would melt under the surgeon’s tools; if too thin, it would break. The
engineers finally settled on a honeycomb-like structure to mimic bones
for their models. The printing process itself took four to 10 hours for
each print.
The 3D printing effort was led by Caffrey, in the lab of professor Sah
at the Jacobs School of Engineering at UC San Diego. The inspiration and
foundations for the study came from BENG 1, a hands-on engineering
class that Sah, among the world leaders in tissue engineering and
cartilage repair, co-taught in 2015 and Caffrey helped set up. Students’
3D printed models of complex ankle bone fractures from CT scans of UC
San Diego patients. BENG 1 continues to be a part of the “Experience
Engineering” initiative introduced by Albert P. Pisano, dean of the
Jacobs School of Engineering at UC San Diego.
Caffrey is now working on his medical degree at the UC San Diego School
of Medicine. He is still collaborating with Upasani at Rady Children’s
to use 3D printed models to evaluate the best way to surgically correct
hip dysplasia, a developmental deformation or misalignment of the hip
joint found in infants.
Source: University of California San Diego
