Comparative Analysis of Material Characteristics and Biomechanical Performance in Passive Ankle-Foot Orthoses

Year 2024, EARLY VIEW, 1 - 1

Hamid Asadi Dereshgi , Dilan Demir

https://doi.org/10.2339/politeknik.1586101

Abstract

Passive ankle-foot orthoses (AFOs) provide essential joint stabilization and limit excessive movement, serving as a cornerstone in biomechanical gait analysis. This study innovatively developed three distinct passive AFOs using thermoplastic polyurethane (TPU), high-impact polystyrene (HIPS), and polylactic acid (PLA) materials, along with a silicone sole, demonstrating enhanced mechanical properties and functional performance. The materials were analyzed using Field Emission Scanning Electron Microscopy (FE-SEM), tensile testing, finite element analysis (FEA), and gait analysis. In particular, FE-SEM revealed micrometer-scale surface roughness (<50 μm), confirming the materials' microstructural consistency. The PLA-based AFO outperformed the HIPS and TPU variants, exhibiting a ~73.43% and ~98.93% higher strength, respectively, in tensile tests. Additionally, PLA exhibited a 16.04% lower displacement compared to HIPS and a 99.25% lower displacement compared to TPU in FEA. Moreover, gait analysis quantified a 24.14% reduction in ankle angular displacement for the TPU-based AFO, 40.38% for the HIPS-based AFO, and 52.39% for the PLA-based AFO, all relative to the without AFO condition, with the PLA AFO demonstrating the most significant enhancement in joint stabilization. Ultimately, this study revealed notable progress in passive AFO design, highlighted PLA's superior performance in joint stability, and laid the groundwork for future advancements in orthosis designs.

Keywords

Biomechanics, passive ankle-foot orthosis, joint stabilization, gait analysis, finite element analysis

Ethical Statement

The authors of this article declare that the materials and methods used in this study do not require ethical committee permission and/or legal-special permission.

Supporting Institution

Istanbul Arel University

Project Number

2022-ST-002

Thanks

The authors acknowledge the Artificial Intelligence Studies, Application, and Research Center (ArelMED-I) at Istanbul Arel University for providing essential technical support in digital measurements.

Pasif Ayak-Bilek Ortezinde Malzeme Özellikleri ve Biyomekanik Performansın Karşılaştırmalı Analizi

Abstract

Pasif ayak-bilek ortezleri (AFO'ları), eklemlerin stabilizasyonunu sağlamakta ve gereksiz hareketi sınırlayarak biyomekanik yürüme analizinde temel bir unsur olarak hizmet ederler. Bu çalışma, termoplastik poliüretan (TPU), yüksek darbe polistiren (HIPS) ve polilaktik asit (PLA) malzemeleri ile silikon taban kullanarak üç farklı pasif AFO'yu yenilikçi bir şekilde geliştirmiş, bu ortezlerin mekanik özelliklerini ve fonksiyonel performanslarını iyileştirdiğini belirtmiştir. Malzemeler, Alan Emisyonlu Taramalı Elektron Mikroskobu (FE-SEM), çekme testi, sonlu elemanlar analizi (FEA) ve yürüyüş analizi kullanılarak analiz edilmiştir. Özellikle, FE-SEM, malzemelerin mikro yapısal tutarlılığını doğrulayan ve yüzey pürüzlülüğünü mikrometre ölçeğinde (<50 μm) ortaya koyan bir sonuç elde etmiştir. PLA tabanlı AFO, HIPS ve TPU varyantlarına kıyasla çekme testlerinde sırasıyla ~%73,43 ve ~%98,93 daha yüksek dayanım sergileyerek üstün performans göstermiştir. Ayrıca, FEA sonuçlarına göre PLA, HIPS’e göre %16,04, TPU’ya göre ise %99,25 daha düşük yer değiştirme gerçekleştirmiştir. Bunun yanı sıra, yürüme analizleri, AFO'suz duruma kıyasla TPU tabanlı AFO için %24,14, HIPS tabanlı AFO için %40,38 ve PLA tabanlı AFO için %52,39 oranında ayak bileği açısal yer değiştirmesinde azalma olduğunu ortaya koymuş ve PLA tabanlı AFO, eklem stabilizasyonundaki en belirgin iyileşmeyi sağlamıştır. Sonuç olarak, bu çalışma pasif AFO tasarımında önemli bir gelişme ortaya koymuş, PLA'nın eklem stabilitesindeki üstün performansını vurgulamış ve gelecekteki ortez tasarımlarına zemin hazırlamıştır.

Keywords

Biyomekanik, pasif ayak-bilek ortezi, eklem stabilizasyonu, yürüyüş analizi, sonlu elemanlar analizi

Project Number

2022-ST-002

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