Abstract-Text (inkl. Referenzen und Bildunterschriften)
Introduction
Textile processes allow for the fabrication of scalable, 3d-porous scaffolds with adjustable strength and stiffness to match the properties of the native tendons or ligaments. Besides primary stability and strength retention during biodegradation, the elastic properties of the scaffold during multiple loading cycles are a crucial but rarely investigated aspect. In this study, several high-strength long-term biodegradable fibers from different Polycaprolactone (PCL)-materials are investigated in terms of their elastic properties over the duration 36 weeks of in vitro hydrolytic degradation.
Materials and Methods
Filaments were melt spun from five different PCL (see Table) as well as from a PCGL copolymer using a single-screw spinning plant (Fourné Maschinenbau, Germany). The fibers were produced at the highest macromolecular orientation achievable. Segments of the fibers were placed in Phosphate Buffer Solution (PBS) at 37°C for up to 36 weeks in order to mimic the hydrolytic degradation in the human body. At discrete time points of 0, 8, 12, 16, 24, 36 weeks samples were subjected to mechanical characterization. Cyclic uniaxial tensile tests were performed at a strain rate of 200%/min with 180 loading cycles with a load derived from the force within the ACL during running.
Results
A pronounced dependence of the elastic behavior from the base material was observed. Fibers from PC08 and CG955 already failed after 8w of degradation followed by PC12 after 24w while the high-molecular weight PCL candidates mostly maintained their elastic properties throughout the 36 weeks. The elasticity retention after 24w of degradation (compared to prior degradation) varied between 0% (failed samples) to 98% for C100 and 99% for both Sigma 80 and Capa6800, respectively.
Conclusion
Elasticity retention during degradation is an important aspect of a functional tendon or ligament replacement. The choice of the material highly affects whether this can be fulfilled.