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Title:Computer modelling of the residual limb for the development of prosthetic sockets and liners with the cellular structure : doctoral disertation
Authors:ID Plesec, Vasja (Author)
ID Harih, Gregor (Mentor) More about this mentor... New window
ID Burger, Helena (Comentor)
Files:.pdf DOK_Plesec_Vasja_2023.pdf (3,64 MB)
MD5: 1DFBCB0F71807816566B5761BC126842
 
Language:English
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:The production of lower limb prostheses continues to rely primarily on manual methods, which are outdated and characterized by labour-intensive processes, lengthy time requirements, high costs, and a heavy reliance on the expertise of prosthetists. Achieving a satisfactory fit between the residual limb and socket remains a challenge, often leading to discomfort, pain, and potential wearer tissue damage. However, advancements in computer technology and numerical simulation offer an opportunity to predict stresses and strains experienced by the residual limb during prosthesis usage. This, in turn, aids in the development process by enhancing the design of the prosthetic socket and liner through virtual environments. In this dissertation we developed a generic numerical transtibial model to bridge the gap between clinical practice and numerical simulations. Biomechanically validated, this model generates outcomes applicable to a broader amputee population, facilitating comparative analysis of socket and liner designs and materials under different loading conditions. Furthermore, the dissertation explores the utilization of a 3D-printed socket manufactured through the cost-effective fused filament fabrication process, using polylactic acid filament, aiming to reduce the costs and establish a streamlined production process. The 3D-printed socket was evaluated within the virtual environment using the developed transtibial model. The numerical findings indicate that the 3D-printed socket can effectively withstand the loads encountered during the stages of prosthesis donning, single-leg stance, heel strike, and push-off, thereby presenting a viable alternative to the prevalent composite socket. Additionally, a cellular structure composed of a flexible thermoplastic elastomeric material is proposed as a prosthetic liner to enhance comfort by reducing contact pressure while maintaining the required stability. Numerical results indicate that by manipulating cellular parameters such as unit cell type and relative density of the structure, a customized response can be achieved. This customized response effectively reduces contact pressure for a given scenario without increasing displacement, thereby improving comfort while maintaining stability.
Keywords:lower-limb prosthesis, generic numerical transtibial model, 3D-printed socket, cellular structure liner, finite element method
Place of publishing:Maribor
Place of performance:Maribor
Publisher:[V. Plesec]
Year of publishing:2023
Number of pages:XXXI, 127 str.
PID:20.500.12556/DKUM-84368 New window
UDC:[519.6:539.2]:615.477.2(043.3)
COBISS.SI-ID:172145667 New window
Publication date in DKUM:14.11.2023
Views:922
Downloads:111
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
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Licences

License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:30.05.2023

Secondary language

Language:Slovenian
Title:Računalniško modeliranje krna za razvoj ležišč in vložkov protez iz celičnih struktur : = doktorska disertacija
Abstract:Proizvodnja protez spodnjih udov še vedno v veliki meri temelji na ročnih metodah, ki so zastarele in zahtevajo delovno intenziven proces, veliko časa, visoke stroške ter močno odvisnost od protetikovih izkušenj. Doseganje zadovoljivega prileganja med krnom in ležiščem še vedno predstavlja izziv, ki pogosto vodi v nelagodje, bolečino in potencialno poškodbo tkiva. Vendar pa napredki na področju računalniške tehnologije in numeričnih simulacij ponujajo priložnost za napovedovanje napetosti in deformacij, ki nastanejo v krn med uporabo proteze. To pa pomaga v procesu razvoja za izboljšanje konstrukcije protetičnega ležišča in vložka znotraj virtualnega okolja. V disertaciji je predstavljen generični numerični model za transtibialne proteze, ki poizkuša zmanjšati vrzel med klinično prakso in numeričnimi simulacijami. Biomehansko validiran model generira rezultate, ki se nanašajo na širšo populacijo amputirancev, kar omogoča primerjalno analizo oblik ležišča in vložka ter različnih materialov pri različnih obremenitvenih pogojih. Poleg tega je v disertaciji predstavljena uporaba 3D-natisnjenega ležišča, izdelanega s stroškovno učinkovitim postopkom nalaganja taljenega filamenta (ang. fused filament fabrication), pri čemer je bil uporabljen filament iz polilaktične kisline (ang. polyactic acid), v želji po zmanjšanju proizvodnih stroškov in vzpostavitvijo racionaliziranega procesa izdelave. 3D-natisnjeno ležišče je bilo analizirano v virtualnem okolju s pomočjo predhodno razvitega transtibialnega modela. Numerični rezultati kažejo, da 3D-natisnjeno ležišče učinkovito prenese vse obremenitve med fazami nameščanja proteze, enonožne stoje, kontakta s peto in odriva, s čimer predstavlja potencialno alternativo prevladujočemu kompozitnemu ležišču. Dodatno je v disertaciji predlagana uporaba celične strukture, izdelane iz fleksibilnega termoplastičnega elastomernega materiala, kot vložka za protezo, s ciljem izboljšanja udobja z zmanjšanjem kontaktnega tlaka, pri čemer ne zmanjša stabilnosti proteze. Numerični rezultati kažejo, da je mogoče s spreminjanjem parametrov celične strukture, kot so vrsta osnovne celice in relativna gostota strukture, doseči prilagojen odziv. Ta prilagojen odziv učinkovito zmanjšuje kontaktni tlak v določeni situaciji, ne da bi pri tem povečali pomik, s čimer se izboljšuje udobje ob ohranjanju stabilnosti.
Keywords:proteza spodnjih okončin, generični numerični transtibialni model, 3D-tiskano ležišče, vložek iz celične strukture, metoda končnih elementov


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