A novel experimental setup for evaluating the stiffness of ankle foot orthoses

Abstract

ObjectiveThe purpose of this study was the construction of a new semi-automated experimental setup for the evaluation of the stiffness of ankle foot orthoses (AFOs) around an axis aligned to the anatomical ankle joint during the second rocker of the gait. The setup, developed in close collaboration with the orthopedic device company V!GO NV (Wetteren, Belgium), allows measurement of plantarflexion and dorsiflexion in the sagittal plane for a maximal range of motion of 50° (− 25° plantarflexion up to 25° dorsiflexion) in a non-destructive way.ResultsThe mechanical properties of four 3D printed AFOs are investigated, based on the ranges of motion derived from the gait assessment of the patients when they walked with their AFO. The reliability of the stiffness measures was studied by the evaluation of the test–retest repeatability and the intra-tester and inter-tester variability. These studies revealed that the ankle stiffness can be measured with high reliability (ICC = 0.94–1.00). The obtained outcomes indicate that the experimental setup could be applied to measure the ankle stiffness of any topology of AFOs and, in the future, help finding the correlation with the information coming from the gait assessment of the patients.Electronic supplementary materialThe online version of this article (10.1186/s13104-018-3752-4) contains supplementary material, which is available to authorized users.

A validated computational framework to evaluate the stiffness of 3D printed ankle foot orthoses

“…The loads and boundary conditions used in the FE models correspond to a dedicated experimental setup (Figure 2 A and B) specifically designed for the evaluation of the ankle stiffness of AFOs during the second rocker of the gait (Ielapi et al 2018). The fixation of the AFOs in the device is via a custom made clamping system which makes use of medium density fiberboard (MDF) replica blocks of the patients' leg, which contain anatomical landmarks for allowing the alignment of the test rig axis with the anatomical ankle axis.…”

“…In this context, the present study proposes a new standardized framework for the creation of FE models of 3D printed patient-specific AFOs in order to quantify the ankle stiffness and the stress distribution during the second rocker of the gait. More specifically, the aim is the validation of these models through the utilization of a dedicated in-house developed mechanical testing rig (Ielapi et al 2018), that establishes the AFO conditions replicated in the FE simulations. This represents an important step for the future application of the FE models in the prediction of the AFOs behavior in case of pathological conditions.…”

Computational and experimental evaluation of the mechanical properties of ankle foot orthoses

“…In the majority of the articles of this category, the main focus is on measuring the stiffness of the AFOs in the sagittal plane through either a manual 4,5–7,10,13,15 – 18,20,22,24,27 – 29 or automated test rig. 8,11,12,14,19,25,26,31 A definition of the term stiffness was provided by Bregman et al 6 as the moment around the ankle joint exerted by the AFO per degree of ankle joint rotation (Figure 2) and it is measured in N m/°. While AFO stiffness is the most common focus, some authors refer to other mechanical properties such as strain or resistive force (Table 1).…”

“…Some of the articles presented in Table 1 were included in a previous literature study, 50 which only includes studies until 2010. The current literature review considers 11 more articles, realized before and after 2010, including new test rig applications 5,11,12,15 – 17,26,29 and functional analyses 21,23,30 and investigating important parameters which were not covered before, such as the alignment of the AFOs. 11,12,29 In particular, a novel study from Ielapi et al 12 experienced that aligning the AFOs in the setup to their anatomical ankle joint, location of which is derived from the previous gait assessment on the patients, is important for obtaining reliable and repeatable stiffness measures.…”

Efectos en el equilibrio y confort de un calcetín estabilizador en pacientes con diferentes alteraciones neurológicas

“…Los más utilizados son los hechos a medida porque proporcionan una sujeción más segura. Los DAFO limitan menos el movimiento de la articulación que los AFO; esto puede ayudar prevenir la debilidad muscular y aumentar el confort de uso ortopédico 15,16 .…”