Abstract
The current method for prosthetic socket design is a lengthy and costly process which is highly dependent on the experience of the prosthetist. Finite Element (FE) modelling has the potential to improve the efficiency of the socket design process. The aim of this project was to investigate the interaction between the trans-femoral residual limb and prosthetic socket using FE simulations. FE models of the residual limb were created and used to simulate standing and walking loads. The studies were conducted over three separate chapters to allow for objective examination of several novel aspects of the modelling setup. Firstly, the effect of introducing the pelvic bone was examined. The results show that pelvic bone shifted the peak interfacial stresses from the distal end, when the bony geometry was only simulated as the residual femur, to the proximal medial region of the residuum. Secondly, the effect of prosthetic liners was examined in terms of its friction coefficient, thickness, and stiffness values. Experimental testing of prosthetic liners showed that the friction coefficient for all liners decreased in wet conditions compared to dry conditions. Higher peak interfacial stresses were found in the FE models with increase friction coefficient levels at both the residuum-liner and liner-socket interfaces. Furthermore, the results showed that the muscle stiffness, liner stiffness and liner thickness were all statistically significant in terms of the resultant interfacial stresses on soft tissues. Finally, the effect of socket tightness of fit and different socket types was considered. Increased fit tightness for the socket significantly reduced the peak interfacial stress and increased average pressures producing more optimal conditions. With two different prosthetic socket designs the results from bipedal stance were examined against soft tissue damage thresholds. The studies showed that the amount of tissue at risk of viability was related to the socket design.