Adapting to change : influence if a microprocessor-controlled prosthetic knee on gait adaptations

Abstract

Advancement in prosthetic knee design have led to the introduction of microprocessor-controlled prosthetic knees (MPKs). MPKs incorporate sensors that are able to measure prosthetic loading, the knee angle, and knee angular velocity. Based on the sensor information, MPKs determine the optimal level of knee damping. This is in contrast to non-microprocessor-controlled prosthetic knees (NMPKs) whose levels of knee damping are more or less fixed. Because of the variable knee damping, MPKs are thought to be beneficial for individuals with a transfemoral amputation or knee disarticulation. To increase our understanding of the influence of a transfemoral amputation or knee disarticulation on the gait pattern, we performed a systematic review focusing on the adaptation strategies of the intact and prosthetic leg. We found several adaptation strategies that seem to be related to the absence of active ankle function of the prosthetic ankle and foot. In addition, we quantified muscle activation pattern during walking. The results of this experiment are in line with the results of the systematic review. In the second part of the thesis we tested the hypothesis that the use of an MPK is beneficial. We tested this in a randomized cross-over trial. Ten participants were measured twice, once with their own NMPK and once with the Rheo Knee II (an MPK). In addition, we included a control group of non-amputees. The measurements included biomechanical analysis of several tasks including level walking at different walking speeds, starting and stopping of gait and recovery strategies after evoked balance perturbations. The results showed a limited impact of the Rheo Knee II on level walking at different speeds and the starting and stopping of gait. On the balance perturbation experiments, we found that the use of the Rheo Knee II enabled participants to use strategies that are also used by individuals without an amputation to cope with the balance disturbances. We also investigated the influence of the Rheo Knee II on quality of life, balance confidence and functional status which was limited. We believe that future research could focus on complex tasks using ambulant sensors.