Together, cleft lips and palates are the most common birth defects in the United States, requiring repair by plastic surgeons. Cleft lip repairs are typically successful at reproducing a normal facial appearance, but 25% of cleft palate surgeries fail to enable normal speech production, resulting in speech impediments. This computer simulation study shows that palate muscle overlap has a huge effect on the function of the soft palate following surgery and may be one of the most powerful surgical tools for eliminating failures. This conclusion is strongly supported by recent clinical results. Our collaborating surgeon Dr. Kant Lin, the Chief of Craniofacial Surgery at the University of Virginia, has modified his technique based on this research.

1. Helping plastic surgeons improve cleft palate surgery
Josh Inouye, PhD
Biomedical Engineering
Mechanical and Aerospace Engineering
University of Virginia
Postdoc Research Day
May 2nd, 2014
mayo.com

2. Cleft lip
Cleft
palate
mayo.com
INTRODUCTION
Together, cleft lips and palates are the most common birth
defects in the US, requiring repair by plastic surgeons

3. INTRODUCTION
Cleft lip repairs are typically successful at reproducing
a normal facial appearance
Before After

4. INTRODUCTION
However, 25% of cleft palate surgeries fail to enable
normal speech, resulting in speech impediments
The palate might be closed, yet 25% of children do not develop
normal speech, leading to progressive re-repair surgeries and
negative psychological effects from teasing by peers.

5. Perceived by peers as:
Speech impediment effects
More vulnerable to:
- Less intelligent
- Less confident
- Less pleasant
- Less honest
- Less attractive
Lallh & Rochet, 2014
- Bullying
- Teasing
- Learning disabilities
INTRODUCTION

6. Of principal importance in establishing normal speech is uniting the
clefted halves of the main palate muscle at the midline of the palate
INTRODUCTION
Clefted muscle halves
unrepaired
Muscle halves united at
midline
Unrepaired cleft palate Repaired cleft palate

7. INTRODUCTION
The existence and extent of muscle overlap at the midline varies
widely among surgeons and the various surgical techniques
- However, no studies have been published examining the
mechanism and effects of various amounts of overlap!
No muscle overlap
present
Muscle overlap present,
but amount varies
Overlap

8. METHODS
We created a computer simulation to reflect actual palate anatomy
and systematically evaluate the effects of changing muscle overlap
Palate
muscle
Computer simulation
Soft palate
Anterior di-
rection
Palate anatomy
Inouye
et
al.
2015,
Journal
of
Craniofacial
Surgery

9. METHODS
We calculated closure force produced by the palate muscle when
contracted to estimate the risk of impaired speech, with higher
forces being more beneficial
Closure force
calculated
F
Muscle at rest
Midline plane
(cutaway view)
Muscle contracted
Inouye
et
al.
2015,
Journal
of
Craniofacial
Surgery

10. RESULTS
Our simulations show that closure force varies widely with varying
overlap percentages, suggesting that overlap is a crucial element to
surgical success
Separation No overlap Optimal
overlap
Too much
overlap
Closure force (N)
Higher forces suggest
greater probability of
surgical success
−20 −10 0 10 20 30
0
0.2
0.4
% overlap
Inouye
et
al.
2015,
Journal
of
Craniofacial
Surgery

11. Our simulation results are supported
by clinical results
DISCUSSION
Nguyen
et
al.
2014,
Plas3c
and
Reconstruc3ve
Surgery
Least overlap Most overlap

12. Our collaborating surgeon has modified his
procedure because of our modeling work
DISCUSSION
“The
work
has
absolutely
influenced
how
I
do
surgery
for
wide
cle@
palates.
Before
this
work,
I
used
to
suture
the
muscle
end
to
end
during
my
repair.
Since
this
work
has
defined
the
op3mal
physics
of
the
muscle,
I
now
try
to
overlap
the
muscles
by
at
least
20%.”
-­‐Kant
Lin,
MD
President,
American
Society
of
Maxillofacial
Surgeons
Chief,
Division
of
Craniofacial
Surgery
Department
of
PlasNc
Surgery
University
of
Virginia

13. CONCLUSION
Contrary to popular opinion of many plastic surgeons,
muscle overlap (as shown by our simulations) has a
huge effect on the function of the soft palate following
surgery and may be one of the most powerful surgical
tools for eliminating failures of cleft palate repairs.

14. Acknowledgements
Co-authors:
• Kant Lin, MD
• Katie Pelland
• Kathleen Borowitz, CCC-SLP
• Silvia Blemker, PhD
Lab members:
• Geoffrey Handsfield, PhD
• Xiao Hu, PhD
• Kelly Virgilio
• Katie Knaus
• Shawn Russell, PhD
• Nic Fiorentino, PhD