Conception préliminaire d'un câble superélastique pour la stabilisation du grasset des bovins adultes suite à une rupture du ligament croisé crânial

Abstract

Lesions to the Cranial Cruciate Ligament (CrCL) are occasional, but debilitating, in adult cattle. They lead to a degradation of the animal life conditions and to an economical loss for producers, thus requiring surgical interventions. Unfortunately, currently used CrCL surrogates are poorly designed, leading the surgeries to often be ineffective. These deficiencies in designs come, amongst others, from a drastic lack of knowledge on the mechanical properties of the healthy CrCL in cattle. The main objective of this research project was to design a superelastic cable in order to stabilise the stifle joint in adult cattle after a CrCL tearing. Mechanical properties in quasi-static loading of an isolated CrCL have firstly been assessed in order to provide design guidelines. Fourteen specimens harvested from 7 mature cows have been tested. Pre-conditioning was achieved with 30 cycles of loading from 30 to 200 N at a strain rate of 0.02 .s-1. Specimens were then loaded to failure at the same strain rate. The tensile load, maximal elongation and absorbed energy at failure were measured, as well as the stiffness at different levels of elongation (5, 10, 15, 20 and 25 %). Load and elongation at first visual signs of tearing were also recorded. None of these properties were related to the bovine weight, age and side of hind-limb (p > 0.05) and the experimental data suggest that the in-vivo maximal elongation is below 13.5 %. A numerical simulation suggested that a tubular braid of 20 NiTiNOL filaments and internal diameter of 4 mm would replicate these mechanical properties. Each filament has a 0.39 mm diameter and is braided with a 43° angle. A prototype has been manufactured and tested. Its force-elongation diagram was inscribed in the experimental corridor of the tests on CrCL, proving the achievability of such a project. Revision of the surgical technique was also enabled by the current prototype.

Date	18 Dec 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Éric Wagnac (Supervisor) & Yvan Petit (Co-supervisor)