Using Facial Suspension Threads: A Cadaveric StudyUsing Skin Vector Displacement Analysis BACKGROUND Facial suspension threads have been successfully used for facial soft-tissue repositi
Trang 1Using Facial Suspension Threads: A Cadaveric Study
Using Skin Vector Displacement Analysis
BACKGROUND Facial suspension threads have been successfully used for facial soft-tissue repositioning
When using facial suspension threads, it is unclear which technique and/or material has the greatest lifting
effect for the middle and lower face or which technique/material best reduces the appearance of the jowls
Material and Methods Three female and 2 male cephalic specimens of Caucasian ethnicity (65.26 8.3 years;
20.726 2.6 kg/m2) were analyzed in an upright secured position Polydioxanone and polycaprolactone
bidi-rectional barbed facial suspension threads were introduced by an 18 G, 100 mm cannula The single-vector
technique aimed toward the labiomandibular sulcus, and the dual-vector technique aimed toward the
labio-mandibular sulcus and the labio-mandibular angle Computation of vertical lifting, horizontal lifting, and volume
reduction at the jowls and along the jawline were calculated using 3D imaging
RESULTS The dual-vector technique effected a greater vertical lifting effect (4.45 6 2.78 mm vs 2.99 6
2.23 mm) but a reduced horizontal lifting effect (0.336 1.34 mm vs 0.49 6 1.32 mm) The dual-vector technique
effected less volume reduction at the jowls 0.326 0.24 cc versus 0.41 6 0.46 cc and less volume reduction
along the jawline 0.466 0.48 cc versus 0.87 6 0.53 cc (dual-vector vs single-vector)
CONCLUSION This study provides evidence resulting from cadaveric observations for the overall
non-superiority of the dual-vector technique compared with the single-vector technique
The authors declared no potential conflicts of interest with respect to the research, authorship, and publication
of this article S Liew and K Frank contributed equally to this work
Facial suspension threads are specially designed
medical sutures aimed to suspend and lift facial tissue through a minimally invasive approach
They have been shown to create facial soft-tissue
lifting and repositioning with a low risk of
complications, minimal procedure, and recovery
time.1,2This noninvasive modality is expected to have
the fastest growth rate in the aesthetic segment in the
United States over the next 5 years.3One reason for its
increase in popularity is its low costs, less down time,
perceived less invasive nature, and lower costs compared with (invasive) surgical face-lifting procedures.1,2
The material of the suspension threads varies between resorbable and nonresorbable materials, but to date, most of the resorbable materials are either poly-dioxanone (PDO) or polycaprolactone (PCL).4
Another characterizing factor of facial suspension threads is the anchoring modality The thread can be
*Shape Clinic, Sydney, Australia;†Department for Hand, Plastic and Aesthetic Surgery, Ludwig—Maximilian University
Munich, Germany;‡Department of Otolaryngology, University of Toronto, Toronto, Canada;xVancouver Laser & Skin
Care Centre, Vancouver, Canada;║Department of Clinical Anatomy, Mayo Clinic College of Medicine and Science,
Rochester, Minnesota
Supplemental digital content is available for this article Direct URL citations appear in the printed text and are provided
in the HTML and PDF versions of this article on the journal’s Web site (www.dermatologicsurgery.org)
© 2020 by the American Society for Dermatologic Surgery, Inc Published by Wolters Kluwer Health, Inc All rights reserved.
ISSN: 1076-0512·Dermatol Surg 2020;46:1721 –1727·DOI: 10.1097/DSS.0000000000002574
Trang 2barbed unidirectional, bidirectional, or
multidirec-tional or knotted which provides stability for the
anchoring cones.4
These suspension threads are classically positioned at the
level of the superficial muscoloaponeurotic system
(SMAS) A retrospective analysis of 160 patients (136
women and 24 men) underwent facial lifting procedures
using barbed PDO suspension threads reported that the
most frequently observed complication was superficial
displacement with 11.2% (n = 18), followed by erythema
9.4% (n = 15) and skin dimpling 6.2% (n = 10).1The
overall complication rate in that study was 34.4% (n =
55), and it was commented that this could have been due
to the used insertion technique or material sterility.2
Comparing this new but rapidly growingfield in the
aesthetic segment to thefield of soft-tissue filler
injections, it can be observed that experimental or
cadaveric validation studies are missing and that
there is a paucity of data providing robust evidence
for technique effectiveness or complication
management.5 –15To date, it is unclear which
tech-nique and/or material has the greatest lifting effect of
the middle and lower face To address this question,
we conducted an experimental cadaveric split-face
study and compared the single-vector versus
dual-vector insertion technique using PDO and PCL
sus-pension threads for their effectiveness in facial
soft-tissue repositioning
Material and Methods
Study Sample
Three female and 2 male cephalic specimens of
Cauca-sian ethnicity with a mean age of 65.26 8.3 years (range:
55–74 years) and a mean body mass index of 20.72 6
2.6 kg/m2were included in this experimental study The
cephalic specimens were screened and not included into
this analysis if previous facial surgery, trauma, or
dis-eases disrupted the integrity of facial anatomy, especially
the facial soft tissues Each body donor had given
informed consent while alive for the use of his or her
body for medical, scientific, and educational purposes
All aspects of the study conform to the ethical standards
of the country where the study was conducted
Facial Suspension Thread Materials Two different types of absorbable facial suspension threads were used on either the left or the right facial side of the same specimen to investigate the difference
in effectives of the single-vector versus the dual-vector technique On the left side (random choice), a PDO bidirectional barbed facial suspension thread was used, introduced by a 18 G, 100 mm cannula, and on the right side (random choice), a PCL bidirectional barbed facial suspension thread was used, introduced likewise by a 18 G, 100 mm cannula
Insertion Techniques The head of each body donor was positioned and secured in an upright position to account for the effects
of gravity (Figures 1 and 2) The same techniques for the left and for the right side of the face were applied
First, the 2 threads directed toward the labio-mandibular sulcus intended for jowl treatment (ante-rior vector) were positioned on both sides of the face, followed by the 2 threads directed to the mandibular angle (posterior vector) intended for jawline
contouring
The anterior 2 threads were introduced through a dermal access puncture 1 cm anterior and 1 cm supe-rior to the mid portion of the zygomatic arch The 18
G, 100 mm cannula was advanced in the SMAS in the direction of the labiomandibular sulcus The superior (more anteriorly positioned) cannula aimed for a position 2 cm posterior and 1 cm inferior to the corner
of the mouth lateral to the labiomandibular sulcus
The inferior (more posteriorly located) cannula aimed for a point in the SMAS 2 cm posterior and 2 cm inferior to the corner of the mouth also lateral to the labiomandibular sulcus (Figure 1) The average tra-jectory of both threads was measured to be 69°
The posterior 2 threads were introduced through a der-mal access puncture 1 cm superior and exactly at the middle of the zygomatic arch (= 1 cm posterior to the dermal access of the anterior vector) The cannula was advanced in the SMAS in the direction of the mandibular angle The more anteriorly located thread was directed
to a point in the SMAS 2 cm anterior and 1 cm superior to the mandibular angle, whereas the posterior thread was
Trang 3aimed to a point 1 cm anterior and 1 cm superior to the
mandibular angle (Figure 2) The average trajectory of
both threads was measured to be 80°
After anchoring of the distal (inferior) segment of both
threads, the cannula was removed, and the proximal
(superior) segment of the thread was left free and
external to the entry point The anchored distal facial
soft tissues (jowls and jawline) were lifted and engaged
with the proximal (superior) segment of the thread
After the thread was tightly positioned in the facial soft
tissue, the excess material was cut All procedures were
performed by thefirst author of the study (S.L.) to
reduce operator’s dependent and technique variation
Imaging Procedure
The image analysis procedures were conducted as
previously described.16,173D images of the faces were
taken by using a Vectra H1 camera system (Canfield
Scientific Inc., Fairfield, NJ) The first 3D image was
taken at baseline that is before any facial suspension
thread was placed The second 3D image was taken
after the anterior 2 threads directed to the
labio-mandibular sulcus were positioned on both sides of the
face The difference in vertical and horizontal skin
displacement and in volume change at the
labio-mandibular sulcus and along the jawline between the
first and the second 3D image was determined as the
effect of the single-vector technique
The third 3D image was taken after the posterior 2
threads (in addition to the 2 anterior threads) directed
to the mandibular angle were positioned on both sides
of the face The difference to baseline in vertical and
horizontal skin displacement and in volume change of the jowls and along the jawline was determined as the effect of the dual-vector technique
Values for skin displacement are calculated as x-coordinates and y-coordinates comparable to the x-axes and y-axes in a Cartesian coordinate system
The skin displacement in the positive x-axis direction represents skin movement from the chin to the ear (=
horizontal lifting), whereas skin displacement in the positive y-axis direction represents skin movement in the cranial direction (= vertical lifting) All surface analytic procedures were conducted by the same investigator (D.F.) (Figures 3 and 4)
Statistical Analyses Skin displacement of the lateral face and volume changes
of the jowls and along the jawline was computed Dif-ferences in vertical and horizontal skin displacement and volume changes of the jowls and along the jawline were calculated comparing single-vector versus dual-vector effects using a paired t-test and comparing the difference between the used materials (= facial sides) using an independent sample t-test Because of the small sample size (n = 5), paired and independent sample statistic cal-culations were performed using the bootstrapping method based on 1,000 bootstrap samples All analyses were performed using SPSS Statistics 23 (IBM, Armonk, NY), and results were considered significant at a prob-ability level of#0.05 Results are presented with the bias-corrected and accelerated 95% bootstrap interval (BCa 95% confidence interval [CI]).18,19
Results Difference Between Thread Materials Using the Single-Vector Technique
The vertical lifting effect of the PDO threads with the single-vector technique (cranial skin displacement and positive y-axis values) averaged at 4.006 2.69 mm; BCa 95% CI 1.79–6.44, whereas the ver-tical lifting effect using PCL threads was 1.976 1.17 mm; BCa 95% CI 1.04–2.96 with p = 162 (See Supplemental Digital Content 1, Figure S1, http://
links.lww.com/DSS/A431) The horizontal lifting
Figure 1 Photograph showing the vector (black lines) of
the 2 posterior threads (A) A processed 3-dimensional
scan showing the skin displacement vectors, represented
with colored arrows, which were used for the consecutive
analysis (B).
Trang 4effect (posterior skin displacement towards the ear,
positive x-axis values) was for the PDO threads 0.98
6 0.93 mm; BCa 95% CI 0.22–1.79, whereas it was
1.366 0.41 mm; BCa 95% CI 1.05–1.71 for the PCL
threads with p = 426 (See Supplemental Digital
Content 1, Figure S2, http://links.lww
com/DSS/A431) Reduction in volume of the jowls
was 0.516 0.30 cc; BCa 95% CI 0.75–0.22 cc using
PDO threads and was 0.306 0.59 cc; BCa 95% CI
0.29–0.65 cc using PCL threads with p = 499 (See
Supplemental Digital Content 1, Figure S3, http://
links.lww.com/DSS/A431) Volume reduction along
the jawline was 0.966 0.43 cc; BCa 95% CI
0.56–1.26 cc using PDO threads and 0.77 6 0.65 cc;
BCa 95% CI 0.15–1.34 cc using PCL threads with
p = 603 (See Supplemental Digital Content 1, Figure
S4, http://links.lww.com/DSS/A431)
Difference Thread Material Using the
Dual-Vector Technique
The vertical lifting effect of the PDO threads with the
dual—vector technique was 4.08 6 2.60 mm; BCa
95% CI 1.74–6.16 and was 4.83 6 3.20 mm; BCa 95% CI 2.03–7.52 for the PCL threads with p = 694 (See Supplemental Digital Content 1, Figure S1, http://links.lww.com/DSS/A431) The horizontal lifting effect was 1.106 0.01 mm; BCa 95% CI 0.57–1.71 for the PDO threads and 1.08 6 0.94 mm;
BCa 95% CI 0.32–1.85 for the PCL threads with
p = 968 (See Supplemental Digital Content 1, Figure S2, http://links.lww.com/DSS/A431) Volume reduction of the jowls was 0.396 0.17 mm; BCa 95% CI 0.22–0.53 using PDO threads and 0.26 6 0.30 mm; BCa 95% CI 0.03–0.52 using PCL threads with p = 419 (See Supplemental Digital Content 1, Figure S3, http://links.lww.com/DSS/A431) Vol-ume reduction along the jawline was 0.336 0.28 mm; BCa 95% CI 0.10–0.61 using PDO threads and was 0.596 0.63 mm; BCa 95% CI 0.03–1.07 using PCL threads with p = 414 (See Supplemental Digital Content 1, Figure S4, http://
links.lww.com/DSS/A431)
Single-Vector Versus Dual-Vector Techniques Independent of the thread material used, the vertical lifting effect of the single-vector technique was 2.99
6 2.23 mm; BCa 95% CI 1.84–4.44, whereas the vertical lifting effect using the dual vector technique was 4.456 2.78 mm; BCa 95% CI 2.66–5.99 (p = 140) Using the single-vector approach, inde-pendent of the thread material used, horizontal lifting was 0.496 1.32 mm; BCa 95% CI 0.27–1.29, whereas for the dual-vector technique, it was 0.336 1.34 mm; BCa 95% CI 0.46–1.05 (p = 394) Volume reduction of the jowls was 0.41
6 0.46 cc; BCa 95% CI 0.12–0.63 using the single-vector technique and was 0.326 0.24 cc; BCa 95%
Figure 2 Photograph showing the vector (black lines) of 2
anterior threads (A) A processed 3-dimensional scan
showing the skin displacement vectors, represented with
colored arrows, which were used for the consecutive
analysis (B).
Figure 3 A processed 3-dimensional scan showing the
cadaveric specimen after placement of both anterior and
posterior threads (A) The vertical and horizontal
dis-placement was assessed within the blue encircled area (B)
using colored vectors and (C) shows the scatter plot of the
vertical and horizontal skin displacement.
Figure 4 A processed 3-dimensional scan showing the volume change along the jawline (A) and at the marionette line (B).
Trang 5CI 0.18–0.48 using the dual-vector technique
(p = 507) Volume reduction along the jawline was
0.876 0.53 cc; BCa 95% CI 0.58–1.17 using the
single-vector technique and was 0.466 0.48 cc;
BCa 95% CI 0.17–0.74 using the dual-vector
technique (p = 064)
Discussion
The results of this experimental cadaveric split-face
study revealed that none of the outcome measures, such
as vertical lifting, horizontal lifting, and volume
reduc-tion, of the jowls and along the jawline were statistically
significantly influenced by the suspension thread
mate-rial (PDO or PCL) The dual-vector technique that is
combined positioning of suspension threads positioned
toward the labiomandibular sulcus and at the
mandib-ular angle displayed a greater vertical lifting effect of the
middle and lower face as compared with the
single-vector technique that is suspension threads at the
labiomandibular sulcus alone: 4.456 2.78 mm versus
2.996 2.23 mm (dual-vector vs single-vector)
Inter-estingly, the dual-vector technique resulted in less
hori-zontal lifting 0.336 1.34 mm versus 0.49 6 1.32 mm
(dual-vector vs single-vector), less volume reduction of
the jowls 0.326 0.24 cc versus 0.41 6 0.46 cc
(dual-vector vs single-(dual-vector), and less volume reduction along
the jawline 0.466 0.48 cc versus 0.87 6 0.53 cc
(dual-vector vs single-(dual-vector)
A strength of this study is that a standardized
pro-cedure with exactly the same parameters (same
investigator, same material per facial side, same entry
points, and same trajectory of the suspension threads)
was conducted to evaluate the effectiveness of the
procedures Another strength of this study is that study
outcomes were objectively assessed using 3-D surface
scanning.20–26These measurements were based on a
mathematic algorithm and are thus independent of
observer subjectivity Another study strength is the
upright donor positioning to account for gravity A
supine positioning would result in laterally oriented
gravitational effects, thereby reducing generalizability
to real-life clinical scenarios
A limitation of this study, however, is the small
sample size consisting of only 5 cephalic specimens
from 3 female and 2 male Caucasian body donors A larger sample might have provided more robust data and might have eliminated outliers To account for the small sample size, which resulted in not normal distributed data samples, we conducted the boot-strap method based on 1,000 bootboot-strap samples for all calculated statistical analyses This enabled us to resample our data and to obtain normally distrib-uted data samples for the tests performed.18,19,27
Another limitation includes the use of cadavers instead of living patients The cadaveric model was chosen to facilitate more accurate image analysis because the subjects were secured in an upright, fixed position during image acquisition In living individuals, facial expressions and posture changes influence skin position and skin light/shadow rela-tionships, even when using a manual matching algorithm for the alignment of the 3D surface scans
Every patient has different needs when addressing facial aging signs so patient recruitment using a standardized protocol is challenging; a standardized treatment algorithm using the same thread trajec-tory for prescribed facial regions may yield aes-thetically unappealing results In a cadaveric model,
1 protocol (as described above) can be used to obtain objective and standardized results A drawback inherent in cadaveric studies is that cadavers lack blood pressure, muscle tone, regular tissue pressure, have a different temperature than living individuals, and are older than most aesthetic patients (range:
55–74 years)
The basic mechanism of action behind facial suspen-sion threads is primarily mechanic and was repro-duced in this cadaveric model Because of the mechanical material-tissue interaction through the barbed sutures facial tissues arefirst tightly secured to the suspension thread, repositioned to the new loca-tion and then anchored The placement of the thread at the SMAS level is important to improve the suspension capability of the barbs onto afibrous layer, rather than a fatty layer with higher chance of cheese wiring
This tissue repositioning has local and regional effects
Using the single-vector technique, facial soft tissues of the medial and lateral midface are being repositioned closer to the entry point of the suture that is to the zygomatic arch
Trang 6Besides the vertical lifting component, the
single-vector technique also had a horizontal lifting
compo-nent as the suspension thread trajectory was 69°
toward the labiomandibular sulcus As the additional
vector of the dual-vector technique had a trajectory of
80°, no additional horizontal lifting effect was
observed On the contrary, the vertically oriented
lifting effect reduced the horizontal lifting effect of the
single-vector technique because the soft tissues were
moved cranially toward the applied suspension thread
trajectory without having any additional horizontal
lifting component (Figures 1 and 2)
Along with the above described local effects, regional
effects were observed Due to tissue repositioning, a
volume decrease in the lower face that is jowls and
along the jawline was observed The volume
reduc-tion after the single-vector technique was 0.416
0.46 cc of the jowls and 0.876 0.53 cc Interestingly,
after the insertion of the second vector directed
toward the mandibular angle, volume in the lower
face increased and the overall effect after the
dual-vector technique was reduced when compared with
the single-vector technique: increase in jowls volume
by 0.09 cc to 0.326 0.24 cc and along the jawline by
0.41 cc to 0.466 0.48 cc after the dual-vector
tech-nique These results are contradictory to the vertical
lifting effect results, which reveal an additive effect of
both suspension thread vectors However, this effect
can be explained by the assumption that an increased
vertical lifting effect (4.456 2.78 mm vs 2.99 6
2.23 mm [dual-vs single-vector]) results in a cranial
displacement of mandibular soft tissue, which
ulti-mately lead to a reduced volume reduction after the
dual-vector technique It could be hypothesized
that a greater cranial soft-tissue displacement results
in a greater mandibular soft-tissue repositioning
from inferior to superior to the jawline This could
result in the observed volume increase after the
dual-vector technique The jawline soft tissues include the
supraplatysmal jowl fat compartment,28which has
been shown to descend with aging and the
sub-platysmal deep fat located around the facial artery
and vein at their mandibular crossing.13The
repo-sitioning of these fat compartments might have a
beneficial effect when neck contouring is targeted
This was however not the objective of this study
Future studies with a larger cadaveric sample size or conducted in living patients will need to address the emerging additional questions raised from the pre-sented experiments
Conclusion This study provides evidence resulting from cadaveric observations for the overall nonsuperiority of the dual-vector technique compared with the single-vector technique Using an upright cadaveric model and 3D imaging, it was revealed that no statistically significant difference between the used materials was observed
The dual-vector technique had a greater vertical lifting effect (4.456 2.78 mm vs 2.99 6 2.23 mm) but a reduced horizontal lifting effect (0.336 1.34 mm vs 0.496 1.32 mm), less volume reduction of the jowls 0.326 0.24 cc versus 0.41 6 0.46 cc, and less volume reduction along the jawline 0.466 0.48 cc versus 0.87
6 0.53 cc (dual-vector vs single-vector) Future studies will be needed to objectively evaluate the effectiveness
of aesthetic procedures using nonsubjective and reproducible outcome measures
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Address correspondence and reprint requests to: Sebastian Cotofana, MD, PhD, Associate Professor of Anatomy, Department of Clinical Anatomy, Mayo Clinic College of Medicine and Science, Mayo Clinic, Stabile Building 9-38,
200 First Street, Rochester, MN, 55905, or e-mail:
cotofana.sebastian@mayo.edu