Scaffold development for Rotator Cuff repair
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2017-11-17
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The rotator cuff is a functional anatomical unit located in the upper extremity and it is defined, anatomically, as a group of muscles and their tendons that act to move and stabilize the shoulder. (Opsha, 2008) Rotator cuff tendon injuries are frequent and are responsible for substantial morbidity in athletes, and in working and elder population. As our society continues to age and remain active, these conditions not only have an impact on peoples' quality of life and activities of daily living, but also represent significant burden on social, economic and health terms. (Docheva, 2015) Currently used therapies are mainly limited to pain control and/or tissue replacement, without fully restoring tissue functionality. (Morais, 2015) Although there was an increase in volume of rotator cuff surgeries during the last years, re-tear rates remain high, with structural repair failure remaining the main problem. (Docheva, 2015) Hence, there is a need for repair strategies that can augment the repair by mechanically reinforcing it, while at the same time biologically enhancing and optimizing the intrinsic healing potential of the tendon. Ultimately, tissue-engineering based alternatives, have been the target of extensive investigation and several biological, natural, and synthetic scaffolds have been proposed for rotator cuff tendon repair. (Richetti, 2012) However, to develop a structure that properly mimics the mechanical performance of the native tissue remains a challenge. (Morais, 2015) Textile manufacturing techniques have been used in a wide range of engineering applications and have recently attracted great attention as potential biofabrication tools for engineering tissue constructs. The versatility of textile structures allows for tailoring their architecture, being possible to control the resulting physical properties and cellular behavior of the scaffolds. (Aibubu, 2016; Akbari, 2016) In this work, four textile constructs, two three-dimensional (3D) and two planar warpknitted structures were evaluated as potential scaffolds for rotator cuff tendon repair. Polyethylene terephthalate (PET) was the chosen base polymer for the structures because of its biocompatibility and excellent mechanical properties. Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electronic Microscopy (SEM), Porosity tests, Absorption tests, Tensile tests and Suture pull-through tests were performed to characterize the structures under study. All matrices presented regular patterns, with well oriented fibers. The estimated fiber diameter, mean pore size and porosity levels of all structures can be consider adequate for tissue-engineering applications. All structures demonstrated similar liquid absorptive capacity and wicking behavior. Regarding the mechanical characterization, structure D demonstrated failure load, stress at failure and elastic modulus values that can be considered suitable for rotator cuff tendon repair. Although the obtained stiffness and failure strain values were not ideal, pre-tensioning techniques were concluded to be adequate to increase stiffness and lower the overall elongation of the structures. Furthermore, this construct demonstrated a value for maximum suture retention load close to the required. Thus, it was concluded that among all constructs, structure D meets the minimum requirements to serve as a scaffold for rotator cuff tendon repair
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Master Dissertation in Biomedical Engineering