Effect of trim line on stiffness in dorsi- and plantarflexion of posterior leaf spring ankle-foot orthoses.

[Purpose] This study aimed to objectively clarify the effect of the trim line setting on the stiffness of posterior leaf spring ankle-foot orthoses. [Participant and Methods] Posterior leaf spring ankle-foot orthoses were fabricated with two thickness levels and three trim line conditions for the posterior upright width and the dorsi- and plantarflexion moments and stiffness exhibited by the orthoses were measured using an evaluation tester. [Results] The trim line of the posterior upright width affected the dorsiflexion moment generated by the orthoses in plantarflexion. [Conclusion] A strong linear correlation was found between posterior upright width and orthotic stiffness, suggesting that it is highly feasible to standardize orthotic settings according to individual conditions of patients after stroke, even for posterior leaf spring ankle-foot orthoses.

Analysis of Pressure Distribution in Transfemoral Prosthetic Socket for Prefabrication Evaluation via the Finite Element Method.

In this study, we estimated and validated the pressure distribution profile between the residuum and two types of prosthetic sockets for transfemoral amputees by utilizing a finite element analysis. Correct shaping of the socket for an appropriate load distribution is a critical process in the design of lower-limb prosthesis sockets. The pressure distribution profile provides an understanding of the relationship between the socket design and the level of subject comfortability. Estimating the pressure profile is important, as it helps improve the prosthesis through an evaluation of the socket design before it undergoes the fabrication process. This study focused on utilizing a magnetic resonance imaging (MRI)-based three-dimensional (3D) model inside a predetermined finite element simulation. The simulation was predetermined by mimicking the actual socket-fitting environment. The results showed that the potential MRI-based 3D model simulation could be used as an estimation tool for a pressure distribution profile due to the high correlation coefficient value (R2 > 0.8) calculated when the pressure profiles were compared to the experiment data. The simulation also showed that the pressure distribution in the proximal area was higher (~30%) than in the distal area of the prosthetic socket for every subject. The results of this study will be of tremendous interest for fabricators through the use of a finite element model as an alternative method for the prefabrication and evaluation of prosthetic sockets. In future prosthetic socket fabrications, less intervention will be required in the development of a socket, and the participation of the subject in the socket-fitting session will not be necessary. The results suggest that this study will contribute to expanding the development of an overall prefabrication evaluation system to allow healthcare providers and engineers to simulate the fit and comfort of transfemoral prosthetics.