Höfundar:
Anna Ármannsdóttir, Kristin Briem, Sigurður Brynjólfsson, Christophe Lecomte
Introduction: Changes in the design and function of prosthetic devices may lead to measurable changes in lower limb biomechanics that are not necessarily perceived by prosthetic users. The purpose of the study was to explore participants’ perceptions to alterations of prosthetic foot stiffness in light of measurable biomechanical changes.
Methods: A novel variable-stiffness ankle unit was built on a commercially available prosthetic foot and used for this study. Kinetic and kinematic data were collected with an 8-camera motion analysis system and an instrumented treadmill while five male participants with trans-tibial amputation walked up a 7.5° incline with each of three stiffness settings. Documentation of their perceptions were analysed, as were sagittal plane biomechanical variables.
Results: The participant’s perception of functional performance was influenced by prosthetic stiffness. Statistically significant effects were only observed for biomechanical variables directly related to prosthetic ankle kinematics and kinetics, i.e. peak prosthetic ankle dorsiflexion, peak prosthetic foot power and dynamic joint stiffness during controlled dorsiflexion (DJS-CD). Analyses of each participant’s data revealed both varied perceptions and kinematics among participants.
Conclusions: Although altering prosthetic stiffness influenced the amputees’ experience, immediate effects on the gait pattern were minimal. The diverse movement strategies used by participants, and variability in their perceptions indicates that physical characteristics and personal habits may influence the effects that discrete changes to the prosthetic foot will induce. This is important to acknowledge and account for as a more personalised approach is being emphasised in the design and prescription processes of prostheses, and in rehabilitation guidelines.