Biomedical subjects

G K Klute

Publications and source records attributed to G K Klute.

4 recordsLinked to original sources

PubMed2005

Comparison of human turning gait with the mechanical performance of lower limb prosthetic transverse rotation adapters.

Given the importance of minimizing transverse plane shear stress on soft tissue, several transverse rotational adapters (TRAs) are available for incorporation in lower limb prostheses. This study compares kinetic and kinematic data from human subjects during straight and turning gaits to the mechanical performance of several TRAs. Physiological data were collected from three individuals walking straight and turning at self-selected speeds around a 1 m radius circle. The average peak torques and range of motion for normal subjects while turning were 8.2 Nm and 26 degrees (outside leg), 11.8Nm and 20 degrees (inside leg), and 11.4 Nm and 20 degrees (right leg) during straight gait. Each TRA was mechanically tested without axial loading in a servo-hydraulic material testing system (MTS) over its rotational range at 0.5 dergrees/s and 60 degrees/s. The TRAs with axial compression were also tested at 0.5 degrees/s under a 736N (75kg mass) axial load. Applying these torques to the different TRAs yielded 3 to 35 degrees rotation, depending on the elastomer installed. Some TRAs had nearly constant stiffness, while others stiffened with rotation. The TRAs also varied in their average maximum stiffness from 0.4Nm/degree to 2.7Nm/degrees. Normal subjects exhibit interior vs. exterior asymmetrical torques and displacements; however, only one of the TRAs is designed to allow asymmetrical stiffness, and none have asymmetric ranges. Prosthetists and physicians can use these data to better interpret amputees' qualitative remarks and to prescribe the correct TRA and/or elastomer. This information also forms a basis for further design and development of novel torque absorbing prosthetic adapters.

Amputees↗

PubMed2004

Modelling the effect of prosthetic feet and shoes on the heel-ground contact force in amputee gait.

Gait laboratory measurements have been widely used to explore footwear and prosthetic effects on intact and amputee gait in spite of the confounding effects of adaptation, acclimation and inherent variability of human subjects. To facilitate understanding of the variables that affect impact forces that arise from heel-ground contact during amputee walking, a lumped parameter model is proposed to simulate the movement of the human body, prosthetic components and footwear during the period immediately following initial contact. Non-linear viscoelastic properties of prosthetic feet have a proportional relationship to both the magnitude of the impact peak and the rate of increase in the ground reaction force (GRF) immediately following initial contact. Footwear, in spite of a larger capacity to dissipate impact energy than a prosthetic foot alone, can actually amplify the magnitude of the impact peak. These results suggest limitations in the ability of conventional prosthetic feet and footwear to attenuate transmission of potential tissue-damaging forces.

Amputees↗

PubMed1992

An optimal controller for an electric ventricular-assist device: theory, implementation, and testing.

This paper addresses the development and testing of an optimal position feedback controller for the Penn State electric ventricular-assist device (EVAD). The control law is designed to minimize the expected value of the EVAD's power consumption for a targeted patient population. The closed-loop control law is implemented on an Intel 8096 microprocessor and in vitro test runs show that this controller improves the EVAD's efficiency by 15-21%, when compared with the performance of the currently used feedforward control scheme.

Computers↗

PubMedDate not supplied

Mechanical properties of prosthetic limbs: adapting to the patient.

Lower-limb amputees have identified comfort and mobility as the two most important characteristics of a prosthesis. While these in turn depend on a multitude of factors, they are strongly influenced by the biomechanical performance of the prosthesis and the loading it imparts to the residual limb. Recent years have seen improvements in several prosthetic components that are designed to improve patient comfort and mobility. In this paper, we discuss two of these: VSAP and prosthetic foot-ankle systems; specifically, their mechanical properties and impact on amputee gait are presented.

Amputees↗