Tensile strength for both fused, zero gauge sutures is above the required tensile strength of 80

1
ThermalFuse Suture Katie Good1, Emily
Schaefer1 Advisors Bruce Beyer, M.D. 2, Paul
King, Ph.D.1 1Department of Biomedical
Engineering, Vanderbilt University, Nashville,
TN 2Department of Obstetrics and Gynecology,
Vanderbilt University Medical Center, Nashville,
TN
Materials Methods (cont.)
Results Discussion (cont.)
Tensile strength for both
fused, zero gauge sutures is above the required
tensile strength of 80 100 N.
In effort to make this procedure more compatible
for the operating room, we have designed a
heating element that uses the same basic
principles as a hair straightener. The new
heating element uses coiled stainless-steel wire
as a thermally conductive heat source with a gold
plated aluminum heating surface attached to a
modified hemostat (Figure 2). This heating
element has a smaller heated surface area than
the hair straightener. After the
sutures were fused their tensile strengths were
determined using an Instron Tensometer from the
Skin Disease Research Core Center (SDRCC) at
Vanderbilts Medical Center. To ensure the
strength of the fused sutures was comparable to
traditionally tied sutures, an experienced
surgeon tied three Vicryl sutures of each gauge.
Each suture was placed between the vacuum
activated clamps on the top and bottom of the
suture. The sutures were placed in the
tensometer so that the fused or tied junction was
not in either clamp. The Blue Hill software
captured and calculated the tensile strength of
each suture as the tensometer pulled on opposite
ends. The true tensile strength was then
calculated according to the cross-sectional area
of the suture. Three tests were run for each of
the suture gauges, temperatures, and closing
methods.
Gauge Heat Setting Temperature (oF) Average Tensile Strength (N)
0 7.5 165 186.255
0 9 198 241.811
0 Tied N/A 207.744
2 7.5 165 19.945
2 9 198 58.908
2 Tied N/A 63.375
Table 2. Average tensile strength at break for
all tests
Materials Methods
Results Discussion
Conclusions
Developed suture technology to assist Dr. Beyer
in tying sutures during procedures involving deep
cavity and thick tissue. Applying heat to the
Vicryl sutures did not compromise the integrity
of the material. The fusing technique was shown
to be a feasible method of suture closure at the
higher temperature (198oF). The strength of the
fused suture was also comparable to the strength
of the tied suture. Since the suture strengths
are comparable, the fusing method is advantageous
in cesarean sections and hysterectomies because
it decreases the risk of infection and internal
bleeding caused when a suture opens.
The Dexon sutures did not successfully fuse when
exposed to thermal conduction, however the Vicryl
sutures did fuse together creating a reliable
suture closure method. Since the Dexon sutures
did not fuse, further testing and research was
conducted using only the Vicryl sutures. The
Vicryl sutures fused at 198 oF had a tensile
stress comparable to the tied sutures of the same
gauge. The sutures fused at 165 oF had a lower
tensile stress than the sutures fused at 198 oF
or the tied sutures (Figure 3 and 4). Missing
data was a result of the tensometer not
functioning properly or the suture slipping out
of the clamps. The average tensile strength
across the trials was also calculated and is
listed in Table 2.

• 0 coated, braided, undyed Vicryl (Ethicon,
  Somerville, NJ) sutures
• 2-0 coated, braided, undyed Vicryl (Ethicon,
  Somerville, NJ) sutures
• 3-0 uncoated, braided, undyed Dexon
  (Tyco/Healthcare, Norwalk, CT)
• Vidal Sassoon Hair Straightener (Model VS189C,
  Helen of Troy L.P., El Paso, TX)
• Hemostat
• 13 mm cylinder
• Tensometer (Instron, Canton, MA)
• The suture was wrapped once around a rigid
  cylinder, the ends of the suture were clamped by
  hemostats, and than twisted together. Once the
  twisted suture was flush against the cylinder,
  the twisted suture was clamped by the hair
  straightener and heat was applied (Figure 1).
  Two different temperature settings were used to
  find the optimal fusing temperature (Table 1).
  Higher temperatures were tested, but melted the
  suture material too quickly.
• Coating is polygalactin 370

Future Directions

• Have surgeons perform simulated procedure and
  give feedback
• Develop a heating element enclosed in
  steralizable thermoplastic material
• Test fused sutures in tissue

References Acknowledgements

• Frishman, G.N., Schwartz, T., Hogan, J.W.
  (1997). Closure of Pfannenstiel skin incisions
  Staples vs. subcuticular suture. Journal of
  Reproductive Medicine, 42 (10), 627-30.
• Kolt, J. D. (2003). Use of adhesive surgical tape
  with the absorbable continuous subcuticular
  suture. ANZ Journal of Surgery, 73 (8), 626629.
• "C-Section Rate At All-Time High in U.S."
  Forbes.com. 17 Aug. 2006.
• "Women's Reproductive Health Hysterectomy."
  Centers for Disease Control and Prevetion. 16
  Nov. 2006. Department of Health and Human
  Services. 10 Apr. 2007 lthttp//www.cdc.gov/reprodu
  ctivehealth/WomensRH/Hysterectomy.htmgt.
• Declercq, E., Barger, M., Cabral, H. J., Evans,
  S. R., Kotelchuck, M., Simon, C., Weiss, J.,
  Heffner, L. J.Maternal Outcomes Associated With
  Planned Primary Cesarean Births Compared With
  Planned Vaginal Births, Obstet Gynecol 109,
  669-677, 2007.
• Skin Disease Research Core Center, Dr. Jayastri
  DasGupta
• Vanderbilt Medical Center Hospital Supply
• Aaron Coffey
• Dr. Thomas Harris

Number Gauge Heat Setting Temperature (oF) Exposure Time (s)
3 0 7.5 165 40
3 0 9 198 40
3 2 7.5 165 40
3 2 9 198 40
Table 1. Suture fusing time and temperature