In vitro mechanical testing of braided polyurethane elastic fiber and braided polyester for equine laryngoplasty.

Abstract

OBJECTIVES: In vitro comparison of the mechanical properties of braided polyurethane elastomer (Lycra&#xae;) and braided polyester (Ethibond&#x2122;) (1) when inserted into the muscular process of the arytenoid cartilage and (2) as suture loops. STUDY DESIGN: Experimental. ANIMALS: Equine cadaver larynges (n&#x2009;=&#x2009;15). METHODS: The muscular processes (n&#x2009;=&#x2009;30) of the arytenoid cartilages were dissected from each larynx and embedded in a resin base. Lycra&#xae; and Ethibond&#x2122; prostheses were randomly allocated to the left or right muscular process and each underwent cyclic fatigue (25-50&#x2009;N) followed by load-to-failure testing. Isolated suture loops of Lycra&#xae; (n&#x2009;=&#x2009;25) and Ethibond&#x2122; (n&#x2009;=&#x2009;25) also underwent the same cyclic fatigue followed by load-to-failure testing (n&#x2009;=&#x2009;20) or a creep testing protocol (25&#x2009;N for 10&#x2009;min; n&#x2009;=&#x2009;5). RESULTS: Lycra&#xae; prostheses pulled through the cartilage in a significantly greater proportion of cyclic tests (P&#x2009;=&#x2009;.015) and at lower mean (&#xb1;SD) loads, (95.9&#x2009;&#xb1;&#x2009;23.4&#x2009;N) during load-to-failure testing than Ethibond&#x2122; prostheses (155.2&#x2009;&#xb1;&#x2009;24.4&#x2009;N; P&#x2009;=&#x2009;.0041). Lycra&#xae; had a significantly greater displacement with and without a cartilage interface when compared to Ethibond&#x2122; (P&#x2009;<&#x2009;.001, P&#x2009;<&#x2009;.002). The Lycra&#xae; isolated suture loops failed at significantly greater loads (233.0&#x2009;&#xb1;&#x2009;38.7&#x2009;N) during load-to-failure testing than Ethibond&#x2122; loops (201.6&#x2009;&#xb1;&#x2009;47.4&#x2009;N; P&#x2009;=&#x2009;.042). CONCLUSIONS: Lycra&#xae; prostheses embedded in laryngeal cartilage pulled through the cartilage at lower loads than Ethibond&#x2122; prostheses. Lycra&#xae; suture loops were stronger than Ethibond&#x2122; suture loops. Lycra&#xae; had greater displacement than Ethibond&#x2122; in all tests as suture loops or when embedded in cartilage.