Functioning in prosthetic users provided with and without a microprocessor-controlled prosthetic knee – relative effects on mobility, self-efficacy and attentional demand

Abstract: Background: To undergo a lower limb amputation is a traumatic experience affecting the individual on physical as well as psychological levels and often leading to limitations in a person´s daily life. Following an amputation individual often receive a prosthesis to address impairments in mobility and functioning. The mechanical properties of the prosthesis can vary, and the choice of specific components to include in the device has been demonstrated to influence patient outcomes. Studies investigating the relative effects of different prosthetic knee components have generally focused upon physical and biomechanical outcomes, providing a rather narrow view of health-related states in prosthetic users. There is a need to view health and wellbeing of prosthetic users from a broader perspective by evaluating outcomes that reflect a variety of different factors that can influence their functioning.Aim: The overall aim of this thesis was to describe and compare functioning in individuals with a trans-femoral amputation or knee disarticulation and to evaluate the relative effects of using non-microprocessor-controlled prosthetic knees (non-MPK) or microprocessor-controlled prosthetic knees (MPK).Methods: The four studies presented in this thesis used a cross-sectional, quantitative design with different types of data collection methods. These included self-report measures, capacity tests, a survey with two questionnaires and a measure of cortical brain activity during normal level waking and while performing a secondary task. One group of 42 individuals with lowerlimb amputations, using a prosthetic knee with or without microprocessor-control was included in the survey study. Another group of 29 individuals with a lower limb amputation, using a prosthetic knee with or without a microprocessor-control and a control group (n=16) participated in the remaining studies. Statistical tests were used to compare differences between groups using different knee joints, between prosthesis users and controls.Results: Individuals using a non-MPK had lower self-reported mobility and balance confidence as well as poorer results on mobility tests compared to those using an MPK. Results revealed no significant differences in self-rated health, daily step count or general self-efficacy. Increased cortical brain activity was seen in frontal cortex in individuals using a non-MPK in single-task walking compare to the MPK group and controls. A significant increase in brain activity was also seen in prefrontal cortex in dual-task walking compared to single-task walking in those walking with an MPK and controls.Conclusion: Combined results of all four studies suggest that persons provided with an MPK had better mobility, both self-rated and objectively evaluated, and better self-rated balance confidence than those who were using a non-MPK. Results also showed that an individual’s belief in their own ability was associated with the number of hours they use their prosthesis per week. Participants using a non-MPK had higher levels of cortical brain activity in the frontal cortex during walking, suggesting that the attentional demand required to walk was greater than for individuals using an MPK. Of particular interest for health professionals involved in prosthetic rehabilitation was the finding that significant increases in attentional demand were not always reflected in temporospatial gait parameters. This suggests that cognitive demands may not always be reflected in variables that are commonly evaluated in the clinical setting.