title: Mechanical and structural characterization of tibial prosthetic interfaces before and after aging under simulated service conditions.
abstract: Prosthesis interface is one of the most important components to promote individual׳s health and comfort, as it establishes direct contact with the skin and transfers loads generated during gait. The aim of this study was to mechanically characterize, three commercial interfaces (block copolymer, silicone gel and silicone elestomer), under static and dynamic conditions, before and after undergoing a process of chemical aging in synthetic sweat for periods up to 90 days. Static mechanical compression tests were performed on the materials, as well as fatigue tests to assess their static and dynamic mechanical behaviors, respectively. For the second, a sinusoidal load was applied with an appropriate range of deformation for each material. Several analytical techniques were also used to characterize the materials, namely Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and morphology characterization by Scanning Electron Microscopy (SEM). All the tested materials have strong viscoelastic behavior, showing a linear response for small deformations, followed by a nonlinear behavior for higher deformation. The block copolymer and the silicone gel are affected by aging in synthetic sweat in a similar way, with a significant increase of their rigidity after 30 days, followed by a progressive reduction. The silicone elastomer displays a continuous increase of rigidity along the 90 days of storage, being the most sensitive to aging affects. It also exhibits the lowest stiffness value, being suitable for uses that require maximum comfort. All materials demonstrate chemical and structural stability under service simulated conditions.
authors.affiliation: CIEPQPF, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal; ESSUAlg, School of Health, University of Algarve, Avª. Dr. Adelino da Palma Carlos, 8000-510 Faro, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Cavaco
authors.affiliation: CEMUC, Department of Mechanical Engineering, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Ramalho
authors.affiliation: ESSUAlg, School of Health, University of Algarve, Avª. Dr. Adelino da Palma Carlos, 8000-510 Faro, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Pais
authors.affiliation: CIEPQPF, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal. Electronic address: luisa@eq.uc.pt.
authors.forename: L
authors.initials: L
authors.lastname: Durães
mesh_terms: D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D019736:Prostheses and Implants; D012826:Silicone Elastomers; D013499:Surface Properties; D013542:Sweat; D013977:Tibia; D013997:Time Factors; D016474:Weight-Bearing
chemical_list: D012826:Silicone Elastomers
keywords: Aging in sweat; Dynamic-mechanical characterization; Elastomeric interface materials; Tibial prosthesis