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Acta Cirurgica Brasileira

Print version ISSN 0102-8650On-line version ISSN 1678-2674

Acta Cir. Bras. vol.18 no.spe São Paulo  2003 



Experimental model of capsular contracture in silicone implants1


Modelo experimental de contratura capsular em implantes de silicone



Érika Malheiros BastosI;Miguel Sabino NetoII;Lydia Masako FerreiraIII; Élvio Bueno GarciaIII; Richard Eloin LiebanoIV; Yuri Anna HanV

IFellow Plastic Surgery Division - UNIFESP-EPM. Brazil.
IIAssistant Professor of the Division of Plastic Surgery UNIFESP / EPM
IIIHead and Chief of the Division of Plastic Surgery UNIFESP / EPM
IVPhD student from de the Division of Plastic Surgery UNIFESP / EPM
VMedical student from UNIFESP/EPM

Correspondence to



ABSTRACT: The breast implant procedure is one of the most performed into Plastic Surgery and the contracture that occurs the capsule formed around the breast implants one of most frequent complication. We describe here one experimental model of capsule contracture in rats.

KEY WORDS: Capsule. Contracture. Silicone. Rats. Model.

RESUMO: O procedimento cirúrgico implante de silicone mamário é um dos mais realizados dentro da Cirurgia Plástica e a contratura que ocorre na cápsula formada ao redor do implante é uma de suas maiores complicações. Descrevemos aqui um modelo experimental de contratura capsular em ratas.

DESCRITORES: Cápsula. Contratura. Silicone. Ratos. Modelo.




Recently, silicone breast implant surgery has become one of the most searched surgical procedures.

Despite the technological progress in the confection of these prostheses, the surgical procedure may lead to complications, such as seroma, hematoma, rupture, leakage or capsular contracture, being the latter one the most common, requiring a new surgical procedure.

In order to study the pathophysiology and possible treatment for capsule contracture, many animal models have been developed. The most reproducible and with the shortest time needed to contracture up growth were those using rats.1, 2, 3, 4, 5, 6, 7, 8, 9

Many authors have not been able to find histological differences in capsules with and without contracture 1, 9, therefore have tried to evaluate the contracture by its reflection on the implanted miniprostheses internal pressure measure. 4, 9



The object of this study is to present an easy, reproducible and low cost model that objectively reflects the appearance or not of capsular contracture around silicone implants (filled with silicone gel, a commonly used material in augmentation mastoplasties and mammary reconstructions), by measuring the implant internal pressure, and correlating it with hystological findings.


Method description

Adult female rats, Wistar type, weighting from 200 to 250g, kept in light-dark cycle (12/12h), with food and water ad libitum are used.

Two cm (diameter), two ml (volume) silicone gel implants, smooth and textured surface, sterile, were used. (Figures 1 and 2)





The implant procedure is made under general anesthesia, using Zolazepam hydrochloride/ Tiletamine hydrochloride, 25 mg/kg (Zoletil™ 50, veterinary use) and non-sterile conditions. Being the rat under anesthesia, the fur is cleared from the incision site by apprehension and removal. (Figure 3)



A 2 cm transversal incision is done in the lumbar-sacral region.



Then, by dissection, a blind tunnel is made underneath the panniculus carnosum onto the shoulder blades, at both sides, so that the tunnels do not communicate. (Figures 5 and 6)





Finally, the implants are introduced: the smooth surfaced at the right tunnel, the textured at the left. (Figures 7 and 8)







The suture is done using inverted subdermic stitches or simple stitches, with incolor 4.0 mononylon, so that traumas from other animals are avoided. This way, up to 5 animals can be kept in the same cage.

The animals are kept for 90 days and then sacrificed (time required for greatest capsular contracture incidence 4, 9).

After sacrificing the animals with overdose of anesthesia (inhalation of ether), the implant internal pressure secondary to capsular contracture, is measured using a strain gauge transducer, compatible with liquids, with normal range values varying from 0 to 10 mmHg.

A number 19 “scalp” is filled with water, connected to the device and inserted into the prostheses inside the animal. Due to the silicone gel viscosity, injection of 0.2 ml of distillate water may be necessary. The internal pressure is then measured.

The capsules are dissected with the surrounding tissue

The specimens are fixed using 10% buffered formalin solution and processed to hystological cuts. The tissues are embedded in paraffin and slices of 4 μm are stained with hematoxilin-eosion and to visualization of reticulin fibers. Furthermore, 4 μm thick cuts are prepared for imunohistochemic study to macrophage through CD 68 antigen, and blood vessels and myofibroblasts through CD34 antigen. The thickness of the capsule is also measured.



The present simple and reproducible experimental model may lead to a better further pathophysiologyic understanding and consequent new research in the treatment of capsular contracture: a difficult to understand and difficult to solve complication in silicon breast implant surgery.



1. Ksander GA , Vistnes LM, Kosek J. Effect of implant location on compressibility and capsule formation around miniprostheses in rats, and experimental capsule contracture. Ann Plast Surg. 1981;6(3):182-93.        [ Links ]

2. Stark GB, Gobel M, Jaeger K. Intraluminal cyclosporine A reduces capsular thickness around silicone implants in rats. Ann Plast Surg. 1990;24(2):156-61.        [ Links ]

3. Vistnes LM, Ksander GA , Kosek J. Study of encapsulation of silicone rubber implants in animals. A foreign-body reaction. Plast Reconstr Surg. 1978;62(4):580-8.        [ Links ]

4. Clugston PA, Perry LC, Hammond DC, Maxwell GP. A Rat Model for Capsular Contracture: The Effects of Surface Texturing. Ann Plast. Surg. 1994,33(6):595-99.        [ Links ]

5. Carpaneda CA. Inflammatory reaction and capsular contracture around smooth silicone implants. Aesthetic Plast Surg. 1997;21(2):110-4.        [ Links ]

6. Smahel J, Hurwitz PJ, Hurwitz N. Soft tissue response to textured silicone implants in an animal experiment. Plast Reconstr Surg. 1993;92(3):474-9.        [ Links ]

7. Ksander GA, Vistnes LM, Fogarty DC. Experimental effects on surrounding fibrous capsule formation from placing steroid in a silicone bag-gel prosthesis before implantation. Plast Reconstr Surg. 1978;62(6):873-84.        [ Links ]

8. Bucky LP, Ehrlich HP, Sohoni S, May JW Jr. The capsule quality of saline-filled smooth silicone, textured silicone, and polyurethane implants in rabbits: a long-term study. Plast Reconstr Surg. 1994;93(6):1123-31; discussion 1132-3.        [ Links ]

9. Peters CR, Shaw TE, Raju DR. The influence of vitamin E on capsule formation and contracture around silicone implants. Ann Plast Surg. 1980;5(5):347-52.        [ Links ]


Conflict of interest: none
Finantial source: none



Érika Malheiros Bastos
UNIFESP-EPM, Plastic Surgery Division, Surgery Division
Rua Napoleão de Barros, 715, 4º andar
04024-900  São Paulo – SP
Tel: (11)557604118 FAX: (11) 55716579



Data do recebimento: 22/ 04/2003
Data da revisão: 18/05/2003
Data da aprovação: 28/07/2003



1 This research was developed at Plastic Surgery Division of Surgery Department - Federal University of São Paulo - Paulista School of Medicine - UNIFESP-EPM. Brazil.

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