Pain in the neck? New surgical method could be game-changing
Researchers develop technique to improve anterior cervical discectomy and fusion by testing variable angle screws

Date:
April 21, 2022
Source:
Florida Atlantic University
Summary:
Anterior cervical discectomy and fusion is widely used to treat
spinal disorders. The fusion involves placing a bone graft or
'cage' and/or implants where the surgically removed damaged disc
was originally located to stabilize and strengthen the area. The
risk factors for cage migration are multifactorial and include
patient, radiological characteristics, surgical techniques and
postoperative factors.



FULL STORY ========================================================================== Anterior cervical discectomy and fusion (ACDF) is a common type of neck
surgery that involves removing a damaged disc to relieve pressure on
the spinal cord or nerve root and thereby alleviate associated pain,
numbness, weakness or tingling. The damaged disc is removed from between
two vertebral bones along with simultaneous fusion surgery. The fusion
involves placing a bone graft or "cage" and/or implants where the disc
was originally located to stabilize and strengthen the area.


==========================================================================
The use of cages for ACDF are important postoperatively to the alignment
of the cervical spine and to maintain the intervertebral disc height. Few studies, however, have examined the impact of the underlying cancellous
or "spongy" bone contact with regards to handling large loads from the
cage. Moreover, it is still not clear whether a cage with or without
screws will be the best choice for long-term fusion as the micromotion
or sliding distance and subsidence or penetration of the cage still take
place repeatedly.

Researchers from Florida Atlantic University's College of Engineering
and Computer Science, in collaboration with Frank Vrionis, M.D., senior
author of the study and director of the Marcus Neuroscience Institute,
part of Baptist Health; and professor of surgery, FAU's Schmidt College of Medicine, are the first to evaluate the effect of the range of motion,
cage migration and subsidence using variable angle screws. Marcus
Neuroscience Institute has its hub on Boca Raton Regional Hospital's
campus and satellite locations at Bethesda Hospital in Boynton Beach
and Deerfield Beach.

For the study, researchers developed five finite element models from
a cervical spine model. The first model was an intact spine model,
and the second model was an altered model with cage insertion and a
2-level static plate. The other three models were altered models with
the same cage insertion and a 2-level dynamic plate. They compared ACDF
cages with and without screws on the biomechanical characteristics of
the human spine, implanted cage, and associated hardware by comparing
the micro motion and subsidence.

Results of the study, published in The Spine Journal,the journal World Neurosurgeryand Asian Spine Journalshowed that the cage-screw and anterior plating combination model has promising potential to reduce the risk
of micro motion and subsidence of implanted cages in two or more level
ACDFs. This method could increase the stiffness of the construct and
reduce the incidence of clinical and fusion failure following ACDF, which
in turn, could decrease the need for revision surgeries or supplemental posterior realignment.

"Anterior cervical discectomy and fusion is widely used to treat patients
with spinal disorders, where the cage is a critical component to achieve satisfactory fusion results. The risk factors for cage migration are multifactorial and include patient factors, radiological characteristics, surgical techniques and postoperative factors," said Vrionis. "Our results showed that the plate used in our study provided directional stability
and obtained excellent fusion, indicating promising clinical outcomes
for patients with degenerative cervical spine disease." Vrionis further explains that because of the biomechanical stability of the current
construct, there has been no need for a rigid cervical collar, which is typically used by other surgeons.



==========================================================================
"In addition, with more than 100 clinical cases, there has been no
evidence of pseudarthrosis or lack of fusion, which is a treated
complication of anterior cervical disc surgery," said Vrionis.

A lower screw rotational angle resulted in superior biomechanical
performance and lower incidence of migration and subsidence compared
with a higher rotational angle in multilevel applications, regardless
of loading. The researchers believe the underlying mechanism may be due
to the cage-screw bonded to the bone and the constrained bottom of C5
vertebra making it more rigid.

"Our research aims to develop a platform for next generation
patient-specific spine surgery by combining intelligent image process,
AI technology/machine learning, finite element simulation and 3D printing
to help surgeons design a surgery plan for each patient, " Chi-Tay Tsai,
Ph.D., study co-author and a professor, FAU Department of Ocean and
Mechanical Engineering, and director, FAU Spine Biomechanical Laboratory.

Researchers demonstrated that the cage-screw was able to prevent
subsidence in all loading scenarios better than the cage without screws.

"Our clinical and biomechanical data have shown that the outcomes with
the rigid static plate are very good. The main reason may be due to
greater contact area between the cortical and cancellous bone in the
cage-screw than that in unanchored cage constructs," said Tsai.



==========================================================================
ACDF is one of the most commonly performed spinal operations in the
United States with an average of 137,000 procedures performed each year.

"The novel methodology developed by our researchers in collaboration
with Drs.

Vrionis and O'Connor of the Marcus Neuroscience Institute holds great
promise to enhance anterior cervical discectomy and fusion and ultimately
help to alleviate the pain and discomfort patients experience from
various disorders of the spine and neck," said Stella Batalama, Ph.D.,
dean, FAU College of Engineering and Computer Science.

Other study co-authors are Erik Engeberg, Ph.D., professor, FAU Department
of Ocean and Mechanical Engineering; Maohua Lin, Ph.D., research
scientist, FAU Department of Ocean and Mechanical Engineering; Stephen
Z. Shapiro, M.D., a neurosurgery resident at Louisiana State University;
and James Doulgeris, Ph.D., both at the Department of Neurosurgery,
Marcus Neuroscience Institute, Boca Raton Regional Hospital, part of
Baptist Health; Rudy Paul, Ph.D., FAU Department of Ocean and Mechanical Engineering; and Timothy E. O'Connor, Ph.D., Department of Neurosurgery,
Marcus Neuroscience Institute.

The research was funded by the Boca Raton Regional Hospital Foundation
awarded to Tsai, principal investigator.

Video: https://youtu.be/Pc76OTtX4d0

========================================================================== Story Source: Materials provided by Florida_Atlantic_University. Original written by Gisele Galoustian. Note: Content may be edited for style
and length.


========================================================================== Journal Reference:
1. Maohua Lin, Stephen Z. Shapiro, Erik D. Engeberg, Chi-Tay Tsai,
Frank D.

Vrionis. Finite Element Analysis of the Effect of Dynamic Plating on
Two- Level Anterior Cervical Discectomy Fusion Biomechanics. World
Neurosurgery, 2022; DOI: 10.1016/j.wneu.2022.02.032 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220421094148.htm

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