Hybrid structures for Achilles' tendon repair

Abstract

The management of extensive tendon injuries poses a considerable challenge. These cases typically require a partial replacement of the tissue, and conventional treatment options, either grafts or synthetic constructs, present disadvantages. Synthetic constructs may be produced with either non-biodegradable or biodegradable polymers. However, while the former lacks biointegration, the latter requires a compromise between tissue ingrowth and biodegradability, frequently malfunctioning due to inadequate mechanical properties. The present work presents a textile medical device designed to repair the Achilles tendon (AT). This device is based on a core/shell design that mimics the multiscale organization of the native tissue. The core comprises several hybrid braids based on poly(ethylene terephthalate) (PET) and poly(lactic acid) (PLA) yarns, and the shell consists on braided PET yarns surrounding the core. Different PET/PLA compositions of the core braids were studied to optimize biodegradability without compromising mechanical performance. The morphology and mechanical properties of the structures were studied. The hybrid structures presented a non-linear force-strain curve comparable to a representative curve described for a native tendon. A decrease in force and stiffness was observed as the PLA content in the structure increased. Nevertheless, the obtained values for the hybrid structures are promising for AT replacement. Besides, these hybrid structures demonstrated appropriate resistance to cyclic loading and a beneficial creep behavior. The results obtained in the present work fall within the range of values reported for the native AT.

Amination of Polymeric Braid Structures to Improve Tendon Healing: An Experimental Comparison

“…An innovative medical device produced from hybrid textile braids based on PET and PLA yarns was developed in a previous work. [8,9] The designed device presents a core-shell architecture (several hybrid braids surrounded by an exterior shell of braided PET yarns) that mimics the hierarchical morphological features and fulfills the high mechanical demands of tissues such as tendons and ligaments. During the first phase of the repair process, the non-degradable component (PET) protects the cells and newly formed tissue from excessive strains by withstanding physiological loads and providing mechanical support, allowing the body's natural healing process to take place.…”

“…Hybrid braids with a higher PET to PLA ratio demonstrated suitable mechanical properties for the intended purpose. [8,9] As such, the primary purpose of this work was to surface modify the PET yarns, which are present in higher number in the hybrid medical device. PLA was also functionalized to evaluate the impact of the surface modification process on the performance of the hybrid medical device.…”

“…It is known that the primary factor of PLA degradation is hydrolysis, which is influenced by temperature conditions and results in the weakening of mechanical properties. [42] Nevertheless, as already shown in a previous work, [8,9] PET yarns are the primary providers of tensile strength for the produced hybrid braids and, consequently, for the final medical device. As such, the mechanical properties of the previously optimized hybrid braids are main- tained after both treatments and can still fulfill the high mechanical demands of tissues such as tendons or ligaments.…”

“…[7] An innovative medical device produced from hybrid textile braids based on PET and PLA yarns was developed in previous work. [8,9] This device mimics the hierarchical morphological features and fulfills the high mechanical demands of tissues such as tendons and ligaments. The superior tensile properties and creep/fatigue resistance of PET allow this medical device to provide adequate physical support for cell proliferation and differentiation.…”