HAYDARPAŞA NUMUNE TRAINING AND RESEARCH HOSPITAL

DEPARTMENT OF PLASTIC, RECONSTRUCTIVE & AESTHETIC SURGERY

ISTANBUL, TURKEY

Regenerative Tissue Matrix Regenerative Tissue Matrix Protects Against Radiation-Protects Against Radiation-

induced Capsular Contracture in a induced Capsular Contracture in a New In-vivo Model of Silicone New In-vivo Model of Silicone Implant Breast ReconstructionImplant Breast Reconstruction

Ercan CİHANDİDE, MDAdnan UZUNİSMAİL, MD, ProfElif E. AYDIN, MDSıdıka KURUL, MD, Prof*Kayvan SHOKROLLAHİ, MD, MSc, LLM**

* Institute of Oncology, Istanbul University, Istanbul/ Turkey** Department of Plastic Surgery, Ottawa Hospital, Ottawa, Ontario, Canada

• Nothing to Disclose.

DISCLOSUREDISCLOSURE

PURPOSE OF THE STUDYPURPOSE 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.

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.

MATERIALS AND METHODSMATERIALS AND METHODS

*AlloDerm® sheets were wrapped around the silicone implants with their epidermal sides facing to the implant surface and sutured with 5/0 Vicryl®.

• 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.

PREPARATION OF THE PREPARATION OF THE SUBCUTANEOUS POCKETS and SUBCUTANEOUS POCKETS and PLACEMENT OF IMPLANTS IN PLACEMENT OF IMPLANTS IN

CONTROL & EXPERIMENT GROUPSCONTROL & EXPERIMENT GROUPS

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

RADIOTHERAPYRADIOTHERAPY

• The subjects to be radiated were stabilized by administering Xylazine hydrochloride (5 mg/kg İM) and Ketamin hydrochloride (35 mg/ kg İM).

• 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.

MACROSCOPIC FINDINGSMACROSCOPIC FINDINGSCONTROL GROUPCONTROL 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.

• 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.

MACROSCOPIC FINDINGSMACROSCOPIC FINDINGSEXPERIMENT GROUPEXPERIMENT 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).

HISTOPATHOLOGICAL FINDINGSHISTOPATHOLOGICAL FINDINGSCONTROL GROUPCONTROL GROUP

X10 magnification under light microscope X100 magnification under light microscope

• 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).

HISTOPATHOLOGICAL FINDINGSHISTOPATHOLOGICAL FINDINGSEXPERIMENT GROUPEXPERIMENT GROUP

X100 magnification under light microscopeX10 magnification under light microscope

• Analysis showed a statistically very significant (p<0,01) decrease in the mean capsule thickness in the experiment group (mean 20,5 µ) when compared to the control group (mean 37 µ). 0

10

20

30

40

Control Group

ExperimentGroup

Capsule Thickness (µ)

STATISTICAL FINDINGS-ISTATISTICAL FINDINGS-I

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

• Analysis showed a statistically very significant (p<0,01) decrease in myofibroblast and fibroblast count in the experiment group (mean 58.000) when compared to the control group (mean 99.500).

STATISTICAL FINDINGS-IISTATISTICAL FINDINGS-II

0

20000

40000

60000

80000

100000

Control Group

ExperimentGroup

Myofibroblast and Fibroblast Cell Count

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

• Inflammatory cell quantities of control and experiment groups showed NO statistically significant difference (p>0,05) when compared with each other.

• Experiment group’s mean inflammatory cell count was found to be still less than the control group’s count and this is an important point that deserves attention.

STATISTICAL FINDINGS-IIISTATISTICAL FINDINGS-III

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

CONCLUSION-ICONCLUSION-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.

CONCLUSION-IICONCLUSION-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.

• 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.

SIGNIFICANCESIGNIFICANCE