Proof of Concept for the Detection of Local Pressure Marks in Prosthesis Sockets Using Structural Dynamics Measurement

Abstract

The wear comfort of a prosthesis is of great importance for amputee patients. The wear comfort can be affected by changes in the interface between the residual limb and prosthesis socket, which can be caused by time-dependent volume fluctuations of the tissue, leading to unwanted local pressure marks. The basis to ensure time-independent wear comfort of a prosthesis is to identify these changes. Common techniques for identifying these variations have a negative impact on the sensitive interface between the residual limb and prosthesis. The following paper contains a proof of concept for the detection of local pressure marks without affecting the described interface using structural dynamics measurements, exemplarily shown at a prosthetic socket for transfemoral amputees in a test bench scenario. The dynamical behaviour of the investigated system is analysed in the form of frequency response functions acquired for different pressure locations and preloads using an impact hammer for excitation and a triaxial acceleration sensor. The frequency response functions show major changes for the various boundary conditions with respect to their frequency-dependent compositions. The results demonstrate how the utilised method enables the identification of changes in local pressure marks regarding the variation of position and magnitude.

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

“…The test object used in the experiment was an anatomically shaped socket for a transfemoral prosthesis manufactured out of carbon fibre according to current standards. Manufacturing details are reported in [ 20 ]. A pressurised air pocket mimicked the residual limb and its volume fluctuation during the preloading of the socket.…”

“…This study explores the use of structural dynamics measurement methods—specifically, structure-borne sound—as a potential non-intrusive method for analysing local pressure marks in prosthesis sockets. This approach builds on previous research that has demonstrated the transferability of experimental acoustic analysis to medical engineering problems and the acquisition of modal parameters for parameter identification [ 20 , 21 ]. This novel approach comes with new challenges regarding the development of an experimental setup that can offer sufficient transferability to the real prosthesis but allows for enough flexibility to incorporate the latest findings into the configuration of the measurement setup.…”