The Use of the Gradual Yielding Mechanism During Downhill Walking in Persons With Transfemoral Amputation—A Case Study

Abstract

Introduction To avoid collapsing of the prosthetic knee during loading, some prostheses contain a yielding mechanism, which can also be used for a safe downhill gait. The aim of this case study was to investigate 1) the influence of downhill gradient on the utilization of yielding mechanisms during gait in individuals with UTA, 2) whether the yielding gait is linked to altered spatiotemporal parameters, and 3) if prosthetic ankle components influence the selection of the yielding mechanism. Materials and Methods Two participants with transfemoral amputation (UFT1 and UFT2) walked overground at various slopes (from 0° to −15°) with their habitual knee device using an articulating and a rigid prosthetic ankle component. Kinematic and kinetic data were recorded at self-selected walking speed. Results UTF1 switched to the gradual yielding mechanism at −6° and UTF2 at −12°. UTF2 walked with the yielding mechanism with a decreased speed, step, and stride length. The use of an articulating compared with a rigid ankle component did not influence the yielding pattern. Conclusions First, the gradient at which the UTFs first used the yielding mechanism was found to be individual. Second, the yielding mechanism induced different alterations in spatiotemporal parameters to the participant walking at higher speed when not using the yielding mechanism. Third, using an articulating prosthetic ankle component did not alter the yielding gait pattern in two individuals with unilateral transfemoral amputation. The individual differences highlight the need for individual setups taking the different components of the prosthetic limb into account.

Control Framework for Sloped Walking With a Powered Transfemoral Prosthesis

“…This gradual yielding is due to the passive nature of the device, i.e., the device offers no active resistance to knee flexion. Studies such as Alexander et al (2017) have made similar observations with other microprocessor knees. Additionally, the higher ankle dorsiflexion at the beginning and end of the gait cycle while walking upslope implies terrain adaptation.…”