Classification of forefoot plantar pressure distribution in persons with diabetes : a novel perspective for the mechanical management of diabetic foot?

Background: The aim of this study was to identify groups of subjects with similar patterns of forefoot loading and verify if specific groups of patients with diabetes could be isolated from non-diabetics. Methodology/Principal Findings: Ninety-seven patients with diabetes and 33 control participants between 45 and 70 years were prospectively recruited in two Belgian Diabetic Foot Clinics. Barefoot plantar pressure measurements were recorded and subsequently analysed using a semi-automatic total mapping technique. Kmeans cluster analysis was applied on relative regional impulses of six forefoot segments in order to pursue a classification for the control group separately, the diabetic group separately and both groups together. Cluster analysis led to identification of three distinct groups when considering only the control group. For the diabetic group, and the computation considering both groups together, four distinct groups were isolated. Compared to the cluster analysis of the control group an additional forefoot loading pattern was identified. This group comprised diabetic feet only. The relevance of the reported clusters was supported by ANOVA statistics indicating significant differences between different regions of interest and different clusters. Conclusion/s Significance: There seems to emerge a new era in diabetic foot medicine which embraces the classification of diabetic patients according to their biomechanical profile. Classification of the plantar pressure distribution has the potential to provide a means to determine mechanical interventions for the prevention and/or treatment of the diabetic foot

Input torque balancing using a cam-based centrifugal pendulum: design optimization and robustness

In a companion paper (Input torque balancing using a cam-based centrifugal pendulum: design procedure and example, J. Sound Vib.), the cam-based centrifugal pendulum (CBCP) was introduced as a simple, cam-based, input torque balancing mechanism. The differential equation that governs the CBCP cam design was derived and a methodology for solving it was developed. Furthermore, in a design example, the CBCP was applied to balance the input torque of a high-speed cam-follower mechanism, driving the sley of a weaving loom. The present paper firstly shows how the design parameters for this particular design example can be optimized, so as to obtain a compact and technologically feasible mechanism. The formulation of the optimization problem is based on a parameterization of the CBCP rotor and coupler shape. Because of its nonconvex nature, the optimization problem is solved using a multi-start sequential quadratic programming (SQP) approach. A design chart, based on an exhaustive analysis, is introduced which (i) allows the designer to perform the design optimization in a quick and approximative way, and (ii) gives considerable insight into the behavior of the SQP-algorithm. Secondly, the CBCP is applied to an industrial case study, that is, a weaving loom. The robustness of the CBCP is illustrated by showing that input torque balancing solely the sley movement enhances the overall dynamic machine behavior, despite the presence of the non-balanced shed motion. A particular contribution of this part is the determination of the weaving loom regime behavior in the frequency domain, an approach which is believed to be novel in mechanism literature. © 2004 Elsevier Ltd. All rights reserved.status: publishe

Input torque balancing using a CAM-based centrifugal pendulum

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Application of convex optimization techniques to human motion analysis: a first exploration

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A convex optimization approach to dynamic musculoskeletal analysis

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Digital image processing of life/death staining

The quantification of live and dead cells in a substrate is often an essential step in cell biology research. A staining protocol that acts differently on live and on dead cells is applied and the number of cells visible is counted using a microscope. Often this counting is done manually or only evaluated qualitatively. If the number of samples to be analyzed is large, counting live and dead cells will become a labor intensive, and in some cases an unreliable, process. The manual procedure also discards potentially relevant information on the cells beyond their live or dead classification. For example, cell size, shape and distribution cannot be measured manually. Thus, developing a software routine to replace the counting process can result in an increase of both efficiency and quality of the data gathering process. Whether or not the time and/or money spent on creating a dedicated computer algorithm is worthwhile, depends on a large number of factors of which some are specific to the samples and some to the technical expertise available. In a large percentage of cases, creating a computer algorithm may be easier than expected. In order for the reader to correctly asses the difficulty level of his/her specific case, an outline on how to tackle the problem is presented within this chapter. The basic concepts of digital imaging, explained in a possible step by step approach, is offered. It is important to be able to estimate the difficulty level for each specific case. Based on a series of questions the potential of creating a computer algorithm can be offset by the costs to be expected.status: publishe

An in vitro approach to the evaluation of foot-ankle kinematics: Performance evaluation of a custom-built gait simulator

Despite their well-known limitations, in vitro experiments have several benefits over in vivo techniques when exploring foot biomechanics under conditions characteristic of gait. In this study, we present a new setup for dynamic in vitro gait simulation that integrates a numerical model for generating the tibial kinematics control input, and we present an innovative methodology to measure full three-dimensional joint kinematics during gait simulations. The gait simulator applies forces to the tendons. Tibial kinematics in the sagittal plane is controlled using a numerical model that takes into account foot morphology. The methodology is validated by comparing joint rotations measured during gait simulation with those measured in vivo. In addition, reliability and accuracy of the control system as well as simulation input and output repeatability are quantified. The results reflect good control performance and repeatability of the control inputs, vertical ground reaction force, center of pressure displacement, and joint rotations and translations. In addition, there is a good correspondence to in vivo kinematics for most patterns of motion at the ankle, subtalar, and Chopart’s joints. Therefore, these results show the relevance and validity of including specimen-specific information for defining the control inputs.status: publishe