title: Mechanical Performance of Poly Implant Prosthesis (PIP) Breast Implants: A Comparative Study.
abstract: BACKGROUND
  There is societal concern regarding potential health problems associated with breast implants. Much of this distrust climate was a reaction to the Poly Implant Prosthesis (PIP) scandal. Studying the mechanisms of implant rupture is an important step for their improvement. The mechanical behaviour of breast implant shells was studied on explanted and virgin implants. Implants from both PIP and another brand (brand X), currently in the market, were considered.
  
  
  METHODS
  To study the mechanical behaviour of the shell, a total of 940 samples from 11 explants and 5 control implants were analysed. The experimental protocol follows the ISO standards for shell integrity and determination of tensile stress-strain properties. Pearson correlation analyses and the multi-factor ANOVA statistical tests were performed using mechanical test data.
  
  
  RESULTS
  Both PIP control and explants had significant variations of stress (P = 0.0001) and shell thickness (P = 0.000) throughout the implant. The stress was directly related to shell thickness. Shell thickness varied significantly for PIP implants, exceeding the manufacturer's specifications. Regarding the other brand, thickness variation was within manufacturer's specifications.
  
  
  CONCLUSIONS
  The heterogeneous nature of PIP implants was confirmed. The implant shell thickness should be considered as a relevant parameter during the manufacturing process, for quality control purposes. These results may contribute to dispel mistrust and doubt surrounding breast implants, among the medical community and patients.
  
  
  METHODS
  This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .
authors.affiliation: INEGI, LAETA, Faculty of Engineering, University of Porto, Campus da FEUP, Rua Dr. Roberto Frias 400, 4200-465, Porto, Portugal.
authors.forename: Nilza Alexandra Gomes
authors.initials: NA
authors.lastname: Ramião
authors.affiliation: INEGI, LAETA, Faculty of Engineering, University of Porto, Campus da FEUP, Rua Dr. Roberto Frias 400, 4200-465, Porto, Portugal. palsm@fe.up.pt.
authors.forename: Pedro Alexandre Lopes de Sousa
authors.identifier: http://orcid.org/0000-0001-9732-4498
authors.initials: PA
authors.lastname: Martins
authors.affiliation: Department of Plastic Surgery, Gaia Hospital Center, Rua Conceição Fernandes, 4434-502, Vila Nova de Gaia, Portugal.
authors.forename: Maria da Luz
authors.initials: MD
authors.lastname: Barroso
authors.affiliation: Department of Plastic Surgery, Gaia Hospital Center, Rua Conceição Fernandes, 4434-502, Vila Nova de Gaia, Portugal.
authors.forename: Diana Costa
authors.initials: DC
authors.lastname: Santos
authors.affiliation: INEGI, LAETA, Faculty of Engineering, University of Porto, Campus da FEUP, Rua Dr. Roberto Frias 400, 4200-465, Porto, Portugal.
authors.forename: Francisco Bulhosa da Rocha
authors.initials: FB
authors.lastname: Pereira
authors.affiliation: INEGI, LAETA, Faculty of Engineering, University of Porto, Campus da FEUP, Rua Dr. Roberto Frias 400, 4200-465, Porto, Portugal.
authors.forename: António Augusto
authors.initials: AA
authors.lastname: Fernandes
mesh_terms: D001672:Biocompatible Materials / Q000009:adverse effects / Q000592:standards; D019928:Breast Implantation / Q000009:adverse effects / Q000295:instrumentation*; D018427:Breast Implants / Q000009:adverse effects / Q000592:standards*; D020878:Device Removal; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008422:Materials Testing / Q000379:methods; D055595:Mechanical Phenomena; D011474:Prosthesis Design / Q000009:adverse effects / Q000592:standards*; D011475:Prosthesis Failure; D012086:Reoperation; D020034:Silicone Gels / Q000009:adverse effects / Q000592:standards*
chemical_list: D001672:Biocompatible Materials; D020034:Silicone Gels
keywords: Breast implant; Implant thickness; Mechanical behaviour; Poly Implant Prosthesis (PIP)