Exploring Thermal Discomfort Amongst Lower-Limb Prosthesis Wearers

Thesis: Firstly, the research provides a methodological contribution showing how to conduct mixed-methods research to obtain rich insights into complex prosthesis phenomena. Secondly, the research highlights the need to appreciate psychological and contextual factors when researching prosthesis wearer thermal comfort. The research contributions are also converted into an implication for prosthesis design. The concept of 'regaining control' to psychologically mitigate thermal discomfort could be incorporated into technologies by using 'on-demand' thermal discomfort relief, rather than 'always-on' solutions, as have been created in the past.

Amongst lower-limb prosthesis wearers, thermal discomfort is a common problem with an estimated prevalence of more than 50%. Overheating does not just create discomfort to the user, but it has been linked to excessive sweating, skin damage caused by a moist environment and friction. Due to impermeable prosthetic components and a warm moist environment, minor skin damage can result in skin infections that can lead to prosthesis cessation, increased social anxiety, isolation and depression. Despite the seriousness of thermal discomfort, few studies explore the issue, with research predominantly constrained to controlled laboratory scenarios, with only one out of laboratory study. In this thesis, studies investigate how thermal discomfort arises and what are the consequences of thermal discomfort for lower-limb prosthesis wearers. Research studies are designed around the principles of presenting lived experiences of the phenomenon and conducting research in the context of participants' real-life activities. A design exploration chapter investigates modifying liner materials and design to create a passive solution to thermal discomfort. However, this approach was found to be ineffective and unfeasible. Study 1 presents a qualitative study which investigates the user experience of a prosthesis, thermal discomfort and related consequences. Study 2 explores limb temperature of male amputees inside and outside the laboratory, with the latter also collecting perceived thermal comfort (PTC) data. Finally, Study 3 investigates thermal discomfort in the real-world and tracks limb temperature, ambient conditions, activities, and experience sampling of PTC. While there were no apparent relationships presented in sensor data, qualitative data revealed that in situations where prosthesis wearers perceived a lack of control, thermal discomfort seemed to be worse. When combined, the studies create two knowledge contributions. Firstly, the research provides a methodological contribution showing how to conduct mixed-methods research to obtain rich insights into complex prosthesis phenomena. Secondly, the research highlights the need to appreciate psychological and contextual factors when researching prosthesis wearer thermal comfort. The research contributions are also converted into an implication for prosthesis design. The concept of 'regaining control' to psychologically mitigate thermal discomfort could be incorporated into technologies by using 'on-demand' thermal discomfort relief, rather than 'always-on' solutions, as have been created in the past.