Meeting Abstract
82.2 Sunday, Jan. 6 Pulling in two directions: biaxial material properties of fascia lata ENG, CM*; PANCHERI, FQ; LIEBERMAN, DE; BIEWENER, AA; DORFMANN, A; Harvard University; Tufts University; Tufts University cmeng@fas.harvard.edu
We tested the biaxial material properties of goat fascia lata (FL), a highly organized collagenous tissue that is in intimate connection with the thigh muscles. Previous studies show that lower limb fascia plays a key role in limb stability and force transmission across segments, and recent work measuring muscle and fascia strain in vivo provides evidence that the FL may store and recover limb kinetic energy in locomoting goats. Further investigation is critical in determining how fascia stiffness and hysteresis influence its potential to serve a variety of functions during locomotion. Because FL has a sheet-like structure and attaches to muscles and bones at multiple sites, it must be strained biaxially, and its functional potential cannot be assessed using uniaxial tests. Furthermore, in situ experiments suggest that biaxial strains modulate longitudinal stiffness in aponeuroses, fascia-like structures found at muscle-tendon junctions. We used planar biaxial testing with strain control to investigate the hypothesis that, like aponeuroses, fascia stiffness can be modulated by different biaxial strain conditions. Because the two layers of collagen fibers in the FL are oriented approximately perpendicular to each other, we performed biaxial tests on longitudinal and transversely oriented samples in each goat. Samples were cycled to multiple strain levels while the non-cycling direction was held constant at 0% and 3% strain. Results show that FL stiffness and hysteresis are higher in the longitudinal vs. transverse direction and stiffness does not increase with perpendicular strain in either direction. Differences in material response in the longitudinal vs. transverse direction and in aponeuroses vs. fascia are likely related to collagen fiber content and orientation.
