Pig Breast Implant and Capsular Contracture Model

Duration of study – variable but typically 90 days
Lead time – 30 days
Standard results – microbiology, histology, Baker Grade assessments (capsule contraction)

Model Utility:

In 2007 breast augmentation became the leading cosmetic surgical procedure in the United States. Local complications during the years following implantation include capsular contracture (Adams 2006), which is the most common with incidence as high as 50 to 74% according to some studies (Burkhart, 1986; Ersek, 1991). The cause of capsular contracture is still unknown, although it likely includes a wide range of factors including peri-implant infection (Pajkos 2003) and microbial biofilms, stimulating fibrosis around the implant and (Netscher 2001; Dobke 1994).

Our pig model utilizes small breast implants, placed into the porcine teat using a surgical approach that duplicates human breast implant surgery. The model can be further complicated through inoculation of bacteria, for example, Staph aureus.

A series of incisions are made along the animals' ventral (abdominal) midline immediately adjacent to each implantation site on each teat.
The incision is followed by blunt dissection using the surgeon's finger between the breast tissue and the underlying musculature to create a sub-mammary pocket into which the silicone implant can be placed.
Contaminate the surface with bacteria (optional).
Close the incisions and monitor for 90 days.
Assessment parameters include:
- Terminal assessment of microbial bio-burden at day 90.
- Monthly assessment of implant hardening via tactile assessment. Each animal will be anesthetized IAW original protocol and each implant site will be digitally evaluated by an observer blinded to the study t evaluate capsule formation.
- Monthly visual observation of capsular contracture of all implant sites using Baker Grade standard.
- Histology assessment of implant samples at day 90.
  - Capsule thickness
  - Capsule density (gaps between collagen fiber)
  - Granuloma density
  - Inflammation and fibrous formations

How the Model Works:

Example Data:

In the Figure below we show how the presence of bacteria (in this case Staph epidermidis) increases the amount of capsular contracture assessed using the Baker Grade Classification system and how that contracture increases over the duration of the study (100 days).

advantages and disadvantages of this model:

references:

This model provides an exceptional tool for studying breast implants and capsular contracture. Customers use this model to study a range of interventional strategies including antimicrobial coatings and anti-contracture coatings.

The primary disadvantage to this model is its relatively long duration (typically 100+ days).

Minami E, Koh IH, Ferreira JC, Waitzberg AF, Chifferi V, Rosewick TF, Pereira MD, Saldiva PH, de Figueiredo LF. The composition and behavior of capsules around smooth and textured breast implants in pigs. Plast Reconstr Surg. 2006 Sep 15;118(4):874-84.