title: Microstructure and mechanical properties of synthetic brow-suspension materials.
abstract: Levator palpebrae superioris (LPS) is a muscle responsible for lifting the upper eyelid and its malfunction leads to a condition called "ptosis", resulting in disfigurement and visual impairment. Severe ptosis is generally treated with "brow-suspension" surgery, whereby the eyelid is cross-connected to the mobile tissues above the eyebrow using a cord-like material, either natural (e.g. fascia lata harvested from the patient) or a synthetic cord. Synthetic brow-suspension materials are widely used, due to not requiring the harvesting of fascia lata that can be associated with pain and donor-site complications. The mechanical properties of some commonly-used synthetic brow-suspension materials were investigated--namely, monofilament polypropylene (Prolene®), sheathed braided polyamide (Supramid Extra® II), silicone frontalis suspension rod (Visitec® Seiff frontalis suspension set), woven polyester (Mersilene® mesh), and expanded polytetrafluoroethylene (Ptose-Up). Each material underwent a single tensile loading to the failure of the material, at three different displacement rates (1, 750 and 1500 mm/min). All the materials exhibited elastic-plastic tensile stress-strain behaviour with considerable differences in elastic modulus, ultimate tensile strength, elastic limit and work of fracture. The results suggest that, as compared to other materials, the silicone brow-suspension rod (Visitec® SFSS) might be the most suitable, providing relatively long-lasting stability and desirable performance. These findings, together with other factors such as commercial availability, cost and clinical outcomes, will provide clinicians with a more rational basis for selection of brow-suspension materials.
authors.affiliation: Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
authors.forename: Kyung-Ah
authors.initials: KA
authors.lastname: Kwon
authors.affiliation: Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Shipley
authors.affiliation: Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK. Electronic address: m.edirisinghe@ucl.ac.uk.
authors.forename: Mohan
authors.initials: M
authors.lastname: Edirisinghe
authors.affiliation: Moorfields Eye Hospital, UCL Institute of Ophthalmology NIHR Biomedical Research Centre for Ophthalmology, 162 City Road, London EC1V 2PD, UK.
authors.forename: Daniel George
authors.initials: DG
authors.lastname: Ezra
authors.affiliation: Moorfields Eye Hospital, UCL Institute of Ophthalmology NIHR Biomedical Research Centre for Ophthalmology, 162 City Road, London EC1V 2PD, UK.
authors.forename: Geoffrey E
authors.initials: GE
authors.lastname: Rose
authors.affiliation: Department of Materials Science and Metallurgy, Cambridge Centre for Medical Materials, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Rayment
authors.affiliation: Department of Materials Science and Metallurgy, Cambridge Centre for Medical Materials, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
authors.forename: Serena M
authors.initials: SM
authors.lastname: Best
authors.affiliation: Department of Materials Science and Metallurgy, Cambridge Centre for Medical Materials, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Cameron
mesh_terms: D040761:Biomimetic Materials / Q000138:chemical synthesis*; D001763:Blepharoptosis / Q000601:surgery; D019245:Compressive Strength; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D009801:Oculomotor Muscles / Q000601:surgery; D013508:Ophthalmologic Surgical Procedures / Q000295:instrumentation*; D011108:Polymers / Q000737:chemistry*; D019736:Prostheses and Implants; D013537:Sutures; D013718:Tensile Strength
chemical_list: D011108:Polymers
keywords: Brow-suspension; Materials; Mechanical properties; Microstructure; Ptosis