Investigating the mechanical behavior of the human lumbar spine model by using finite element method

Abstract

Understanding the mechanical behavior of the human lumbar spine is important in spinal disorders and treatment. For this reason, spinal mechanics is examined in many biomechanical studies. The aim of this study is to examine the mechanical behavior of the human lumbar spine with the finite element method and to verify it by comparing it with experimental data in the literature. In addition, by trying different models, it is aimed to determine which structure in the spine functions under which loads and to show new researchers how these processes are applied. The human L1-L5 vertebrae were used. There were two models; one had facets as a single body in each without ligaments and the second one had facets as paired bodies at opposing bones with ligaments. Each intervertebral disc included nucleus pulposus, annulus fibrosus, and two end plates. Flexion, extension, left lateral bending, and right lateral bending loads were applied to the models with 4 Nm moment. The range of motions of each spinal segment in degrees were used as the analysis output and compared to the experimental data in the literature to validate the results. According to the results, modeling the facets as a single body caused excessive stiffness, while modeling them as facet pairs at opposing bones caused excessive movement. It can be said that using a model which, has paired facet joints and ligaments, provided converged range of motion values in each L1-L5 spinal segment under flexion/extension and left/right lateral bending moments.

Keywords

• Lumbar spine
• biomechanics
• finite element method

İnsan lomber omurgasının mekanik davranışının sonlu elemanlar yöntemi ile incelenmesi

Öz

İnsan lomber omurgasının mekanik davranışının anlaşılması, omurga rahatsızlıklarında ve tedavisinde önemli bir yer tutmaktadır. Bu sebeple pek çok biyomekanik çalışmada omurga mekaniği incelenmektedir. Bu çalışmanın amacı, insan lomber omurgasının mekanik davranışını sonlu elemanlar yöntemi ile incelemek ve literatürdeki deneysel veriler ile karşılaştırarak doğrulamaktır. Ayrıca, farklı modeller deneyerek, omurgada hangi yapının hangi yükler altında işlev gördüğünü belirlemek ve bu süreçlerin nasıl uygulandığını yeni araştırmacılara göstermektir. Bu çalışmada insan L1-L5 omurgası kullanılmıştır. İlki, faset eklemlerin tek bir gövde olarak modellendiği ligamentsiz bir omurga modeli ve ikincisi faset eklemlerin karşılıklı kemiklerde iki farklı gövde çifti olarak modellendiği ligamentli omurga modeli olmak üzere iki farklı model incelenmiştir. Her bir intervertebral disk, nükleus pulpozus, anülüs fibrozus ve iki adet end-plate’ten oluşmaktadır. Modellere, fleksiyon, ekstansiyon, sola eğilme ve sağa eğilme yükleri 4 Nm’lik moment ile uygulanmıştır. Her bir spinal segmentin derece cinsinden dönme miktarı analiz çıktısı olarak kullanılmış ve doğrulama için literatürdeki deneysel veriler ile karşılaştırılmıştır. Sonuçlara göre, fasetleri tek bir gövde olarak modellemek aşırı direngenliğe neden olurken, karşıt kemiklerde faset çiftleri olarak modellemek aşırı harekete neden oldu. Fasetlerin karşılıklı kemiklerde faset çiftleri olarak modellendiği ve ligamentleri olan bir modelin, fleksiyon/ekstansiyon ve sola/sağa eğilme momentleri altında her bir L1-L5 spinal segmentinde deneysel verilere yakınsayan dönme miktarı değerleri sağladığı söylenebilir.

Anahtar Kelimeler

• Lomber omurga
• biyomekanik
• sonlu elemanlar metodu

Kaynakça

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