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It has been shown that the interface between the prosthetic socket and residual limb (S-RL) interface is an important factor in determining acceptance and outcomes of upper limb prostheses. [1] Among the most common complaint from amputees is that the prosthesis is uncomfortable due to developing skin irritation which is usually attributed to poor fit (Nielson 1990). In order to understand why skin irritations can and do occur it is imperative to examine the biomechanical properties of the S-RL interface. A primary reason behind the development of skin irritation is instability of the socket upon the residuum. Alley (2009) asserts that excess slip, axial rotation, and translation are the facets of instability that cause skin irritations due to friction and shear. Measuring the motion at the S-RL interface is not commonly done and therefore there is still no valid and reliable method to quantify the motion clinically. A licensed prosthesis fabricated a transhumeral residual limb model to fit within a typical, harness suspended transhumeral prosthesis. A custom testing apparatus was built to hold the residual limb model and prosthesis for testing. Eight infrared markers were placed on the prosthesis and residual limb model: Two each respectively on the "wrist", elbow axis, socket, and on the residual limb model. The model consists of 3 rigid segments, the forearm, socket, and residual limb. Pearson r correlations were done to see how strongly correlated the motion analysis calculated values were to the accepted values. All results were significant with a r < = .95 and p < .05.

A prosthetic socket worn by an amputee must serve a wide variety of functions, from stationary support to the transfer of forces necessary to move. Fit and comfort are important factors in determining the therapeutic effectiveness of a socket. A socket that does not fit the subject well will cause movement problems and potentially long-term health issues. Because a subject's residual limb changes volume throughout the day, it is desirable that the socket adapt to accommodate volume changes to maintain fit and comfort. This thesis presents research to manufacture adaptive sockets using selective laser sintering (SLS). This additive manufacturing process allows freedom to design a socket that has both compliant areas that can adapt to changes to the residual limb, as well as rigid regions to provide necessary support for the limb. A variety of concepts are discussed that are intended for manufacture by SLS, and that feature flexible inner membranes in various configurations. For each concept the membrane will be inflated or deflated to match the limb’s change in volume and the thesis also presents a study to determine SLS machine parameters for optimal build results. A series of experiments was created to understand the ability of SLS manufactured plastics to be inflated and the possible performance. / text

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.