Sanders, Joan ESwanson, Eric C2019-10-152019-10-152019Swanson_washington_0250E_20767.pdfhttp://hdl.handle.net/1773/44723Thesis (Ph.D.)--University of Washington, 2019Skin breakdown is a problem that affects many individuals with lower limb loss. Breakdown is caused most commonly by repetitive mechanical stresses that are imposed on the residual limb at its interface with the prosthetic socket. Skin can adapt to become more tolerant to these stresses, thus reducing the risk of breakdown, yet little is understood about this phenomenon and no methods exist for objectively determining if skin has become more load tolerant. These factors have limited the ability of clinicians to more fully understand the health of their patients’ skin and they have limited the ability of researchers to develop improved rehabilitation strategies and therapeutics to enhance the load tolerance of skin. At the root of these needs is the lack of understanding of how skin adapts to mechanical stress. In order to develop a better understanding, new methods are needed that can safely and accurately probe the cutaneous physiology of individuals with lower limb loss. The objective of this dissertation was to develop noninvasive methods to assess the structure and function of skin and then to determine the utility of the developed tools for the investigation of skin adaptation in individuals with lower limb loss. In Aim 1, novel noninvasive techniques were developed to measure key structural and functional features of the cutaneous microvasculature that may be involved in skin adaptation. In Aim 2, these tools were introduced to investigate skin adaptation to mechanical stress on eight able-bodied participants who wore a modified below-knee prosthetic socket for two weeks. Study results demonstrated good repeatability of the OCT-based measurement methods with the exception of some features. No statistically significant differences were found in any of the OCT measurements taken at different time points throughout the study or between the test site and a location-matched control site on the contralateral limb. It is believed that the limb skin was not stressed enough to induce adaptation in the participants. In Aim 3, a case study of three participants with unilateral transtibial limb loss was performed to investigate the skin of chronically-stressed regions of the residual limb using the measurement methods developed in Aim 1. Measurements were compared between a highly stressed region of the residual limb and a location-matched site on the intact contralateral limb. Notable differences in functional and structural characteristics of the microvasculature were found between the two limbs for each study participant and between the residual limbs of all study participants. The epidermis was also thicker in the residual limb versus the contralateral limb for all participants, a difference that was statistically significant. Taken together, this thesis introduced new noninvasive methods for investigating skin adaptation in users of lower limb prostheses, highlighted advantages and limitations related to the developed methods, and identified potential biomarkers for skin adaptation that are worth further investigation.application/pdfen-USnoneLower limb amputationOptical coherence tomographyProstheticsResidual limbSkin adaptationBiomedical engineeringBioengineeringThesis