Towards Management of Residual Limb Volume: Monitoring the Prosthetic Interface Pressure to Detect Volume Fluctuations—A Feasibility Study

Abstract

(1) Motivation: Variations in the volume of the residual limb negatively impact various aspects of prosthesis use including the prosthetic socket fit. Although volume adjustment systems mitigate corresponding fit problems to some extent, some users still find the management of these systems challenging. With the ultimate goal of creating a feedback system that assists users with the management of their volume adjustment systems, this study demonstrates the feasibility of detecting variations in the volume of the residual limb. (2) Methods: Measurements of the interface force at the bottom of the prosthetic socket were used as indicators of variations in the volume of the residual limb. Force sensitive resistors (FSRs) were placed at the bottom of participants’ prosthetic sockets to monitor the interface limb–socket force as participants walked on a flat surface. Two phases of experiments were carried out: The first phase considered variations simulated by three prosthetic sock plies, established the feasibility of detecting variations in the volume of the limb based on the interface force, and further determined the locations at which the interface force could be used to detect variations in the limb’s volume. Having validated the effectiveness of the proposed method in the first phase, the second phase was carried out to determine the smallest detectable variation of the limb’s volume using the proposed method. In this phase, variations simulated by one and two prosthetic sock plies were considered. Four and three volunteers with transtibial amputations participated in the first and the second phases, respectively. (3) Results: Results of the first phase showed that an increase in the volume of the limb resulted in a decrease in the force measured at the distal location of the prosthetic sockets of all participants; however, the smallest detected variation could not be statistically confirmed.

Adjustable prosthetic sockets: a systematic review of industrial and research design characteristics and their justifications

“…The upper-limb study tests were exclusively carried out in controlled environments (such as a laboratory), and rarely examined the impact of adjustment once the socket was fitted, probably due to the upper limb experiencing much less volume fluctuation when compared to lower limbs [ 80 ]. Importantly, studies were often short-term in duration regardless of whether they focussed on upper or lower limb adjustable sockets, greatly limiting the extent to which the safety and durability of these devices could be tested.…”

Approach for Non-Intrusive Detection of the Fit of Orthopaedic Devices Based on Vibrational Data

“…Due to the high inter- and intravariability of prosthetic sockets, this will also be the case for any other form of characterisation. Any measurement on the patient is only a snapshot of the amputation stump, as it is already known that soft tissue has highly nonlinear and time-dependent behaviour [ 28 , 29 , 33 ]. Nevertheless, the correlation shown between the mode shapes and changes in FRFs clarifies that local contact areas influence the dynamical behaviour of prostheses.…”

Volume Fluctuations in Active and Nonactive Transtibial Prosthetics Users

“…Both amputees' distal ends of the limb underwent an extreme volume fluctuation due to the “unrecoverable” soft tissue situated in this area. Unrecoverable soft tissue will experience deformities and loses fluid volume when load and stress are applied [ 31 ]. A similar report was presented by Youngblood et al (2019), where the study emphasized that an active amputee tends to expect high fluid volume loss at the start and less loss lesser later when carrying out an activity [ 3 ].…”