Spencer P. Lake

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Ligament viscoelasticity controls viscous dissipation of energy and thus the potential for injury or catastrophic failure. Viscoelasticity under different loading conditions is likely related to the organization and anisotropy of the tissue. The objective of this study was to quantify the strain- and frequency-dependent viscoelastic behavior of the human(More)
The objective of this study was to assess the precision and accuracy of a nonproprietary, optical three-dimensional (3D) motion analysis system for the simultaneous measurement of soft tissue strains and joint kinematics. The system consisted of two high-resolution digital cameras and software for calculating the 3D coordinates of contrast markers. System(More)
While collagen is recognized as the predominant mechanical component of soft connective tissues, the role of the non-fibrillar matrix (NFM) is less well understood. Even model systems, such as the collagen-agarose co-gel, can exhibit complex behavior, making it difficult to identify relative contributions of specific tissue constituents. In the present(More)
Rest is a common treatment for overuse injuries, but its effectiveness on gene expression has not been systematically evaluated under controlled experimental conditions. We asked whether genes regulated in the supraspinatus tendon as a result of overuse would return to normal levels after 2 or 4 weeks of rest. We used a rat model of tendon overuse that(More)
A soft tissue's macroscopic behavior is largely determined by its microstructural components (often a collagen fiber network surrounded by a nonfibrillar matrix (NFM)). In the present study, a coupled fiber-matrix model was developed to fully quantify the internal stress field within such a tissue and to explore interactions between the collagen fiber(More)
Structural constitutive modeling approaches are often based on the assumption of affine fiber kinematics, even though this assumption has rarely been evaluated experimentally. We are interested in applying mathematical models to understand the mechanisms responsible for the inhomogeneous, anisotropic, and non-linear properties of human supraspinatus tendon(More)
Variations in properties, active behavior, injury, scarring, and/or disease can all cause a tissue's mechanical behavior to be heterogeneous. Advances in imaging technology allow for accurate full-field displacement tracking of both in vitro and in vivo deformation from an applied load. While detailed strain fields provide some insight into tissue behavior,(More)
Tissue-equivalents (TEs), simple model tissues with tunable properties, have been used to explore many features of biological soft tissues. Absent in most formulations however, is the residual stress that arises due to interactions among components with different unloaded levels of stress, which has an important functional role in many biological tissues.(More)
Although linked to several vitreoretinal pathologies including traumatic retinal tears, breaks, and symptomatic vitreomacular traction, the dynamic material behavior of the vitreous body in response to mechanical loads is not well understood. The purpose of this study was to evaluate spatiotemporal patterns of collagen fiber reorganization and vitreous(More)