ALLODERM

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Regenerative Tissue Matrix Protects Against
Radiation-induced Capsular Contracture in a
New In-vivo Model of Silicone Implant Breast
Reconstruction
Ercan CIHANDIDE, MD Adnan UZUNISMAIL, MD,
Prof Elif E. AYDIN, MD Sidika KURUL, MD,
Prof Kayvan SHOKROLLAHI, MD, MSc, LLM
HAYDARPASA NUMUNE TRAINING AND RESEARCH
HOSPITALDEPARTMENT OF PLASTIC, RECONSTRUCTIVE
AESTHETIC SURGERY ISTANBUL, TURKEY
Institute of Oncology, Istanbul University,
Istanbul/ Turkey Department of Plastic
Surgery, Ottawa Hospital, Ottawa, Ontario, Canada
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DISCLOSURE

• Nothing to Disclose.

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PURPOSE OF THE STUDY

• The aim of this study was to assess the effect of
  radiotherapy on encapsulation of AlloDerm
  Regenerative Tissue Matrix-wrapped textured
  silicone implants to test the hypothesis that
  interposition of a biological barrier between the
  implant and tissue pocket may protect against
  capsule formation and severity of contracture.

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MATERIALS AND METHODS

• 20 female Wistar Albino rats weighing 295 grams
  on average were used in the study. Subjects were
  divided into experiment and control groups with
  10 rats in each.
• Group I Control Group 1.5x1 cm silicone
  implants were inserted into subcutaneous pockets
  on the right thoracodorsal areas of the subjects.
  
• Group II Experiment Group 1.5x1 cm silicone
  implants were wrapped in AlloDerm sheets and
  then inserted into subcutaneous pockets on the
  left thoracodorsal areas of the subjects.

AlloDerm sheets were wrapped around the
silicone implants with their epidermal sides
facing to the implant surface and sutured with
5/0 Vicryl.
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PREPARATION OF THE SUBCUTANEOUS POCKETS and
PLACEMENT OF IMPLANTS IN CONTROL EXPERIMENT
GROUPS

• After making a 1.5 cm long incision on the right
  and left thoracodorsal regions of the subjects,
  subcutaneous pockets were prepared under
  panniculus carnosus.
• In experiment group, silicone implants wrapped in
  AlloDerm sheets were placed subcutaneously
  paying attention to bring their textured surfaces
  toward the skin as in control group.

• In control group, naked silicone implants were
  placed subcutaneously paying attention to bring
  their textured surfaces toward the skin.

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RADIOTHERAPY

• The subjects to be radiated were stabilized by
  administering Xylazine hydrochloride (5 mg/kg IM)
  and Ketamin hydrochloride (35 mg/ kg IM).
• Single dose 18 Gy radiation was given with a low
  energy X-ray orthovoltage machine (STABILIPAN
  X). Healthy tissues were protected with use of
  lead blocks.

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MACROSCOPIC FINDINGSCONTROL GROUP

• The implants
• - were easily detected by inspection and
  palpation at 12 weeks postoperatively.
• - revealed a remarkable capsular tissue, fixing
  the implant to the adjacent subcutaneous tissue
  by fibrous bands.
• The skin overlying the implants had a hyperemic
  appearance due to increased neovascularization.
• The capsule surrounding the implant could not be
  released from the subcutaneous tissue.
• In 6 of 10 implants, the implants were found
  folded inside the capsule.

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MACROSCOPIC FINDINGSEXPERIMENT GROUP

• 5 of 10 silicone implants wrapped with AlloDerm
  were hardly seen externally.
• Subcutaneous tissue and fascia were found to be
  thinner when compared to the control group and a
  more fragile capsular tissue was surrounding the
  AlloDerm.
• Macroscopic slicing process revealed that
  AlloDerm and silicone implants were easily
  seperated from each other.
• All implants seemed to preserve their original
  shape.

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HISTOPATHOLOGICAL FINDINGSCONTROL GROUP

• Interfibrillar distances were narrow, fibrosis
  was more extended and the cells of the capsule
  were dyed darker.
• Increased cellularity of myofibroblasts and
  fibroblasts were detected in capsules around the
  implants under light microscope.
• Neovascularization was increased in and around
  the capsular tissue.
• Capsule thicknesses were between 32-59µ (mean
  37µ).

X10 magnification under light microscope
X100 magnification under light microscope
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HISTOPATHOLOGICAL FINDINGSEXPERIMENT GROUP

• Interfibrillary distances were wider than the
  control group. Cells of this group dyed
  relatively lighter.
• Quantity of myofibroblasts and fibroblasts in
  capsule were much lower when compared to the
  control group.
• Capsular tissue could not be distinguished from
  surrounding connective tissue with strict
  borders.
• Capsule thicknesses were between 14-27µ (mean
  20.5µ).

X100 magnification under light microscope
X10 magnification under light microscope
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STATISTICAL FINDINGS-I

• Analysis showed a statistically very significant
  (plt0,01) decrease in the mean capsule thickness
  in the experiment group (mean 20,5 µ)
  when compared to the control group
  (mean 37 µ).

(Statistical analysis and comparison of the
quantitative data were done using Mann Whitney U
test.)
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STATISTICAL FINDINGS-II

• Analysis showed a statistically very
  significant (plt0,01) decrease in myofibroblast
  and fibroblast count in the
  experiment group (mean 58.000) when
  compared to the control group (mean
  99.500).

(Statistical analysis and comparison of the
quantitative data were done using Mann Whitney U
test.)
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STATISTICAL FINDINGS-III

• Inflammatory cell quantities of control and
  experiment groups showed NO statistically
  significant difference (pgt0,05) when compared
  with each other.
• Experiment groups mean inflammatory cell count
  was found to be still less than the control
  groups count and this is an important point that
  deserves attention.

(Statistical analysis and comparison of the
quantitative data were done using Mann Whitney U
test.)
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CONCLUSION-I

• In our first experimental study, we have observed
  positive results about minimizing the capsule
  formation by using fascial grafts and flaps as a
  wrap around fashion, however sufficient amounts
  of fascia to wrap the implants is difficult to
  attain.
• We have seen positive results with usage of
  Alloderm in the second step and
• This third study was designed to examine and
  assess the effect of radiotherapy on capsule
  formation and capsular contracture development on
  AlloDerm wrapped silicone implants.

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CONCLUSION-II

• In accordance with the findings obtained from
  this third stage of our experimental studies, it
  seems that when planning breast reconstruction
  with implants in cases of which postoperative
  radiotherapy is planned, wrapping the breast
  implants with AlloDerm could decrease the
  capsule thickness and as a result might reduce
  the incidence of capsular contracture.

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SIGNIFICANCE

• We demonstrate for the first time a statistically
  significant protective effect of Alloderm
  interposition on radiotherapy-induced capsule
  formation with textured silicone implants. There
  is sufficient weight of evidence to justify
  further studies with Alloderm interposition in
  patients, starting with the small subpopulation
  for whom implant reconstruction has been chosen
  despite the need for radiotherapy or in whom
  future radiotherapy may be a possibility.