Biomechanical and Finite Element Analysis of Compressive Forces on the Lumbar Spine During Lifting Task by Ethiopian Construction Laborers
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Date
2025-12-01
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Addis Ababa University
Abstract
Lower back pain (LBP) is a prevalent issue, particularly in physically demanding occupations like construction work, where heavy lifting and poor ergonomic practices significantly increase injury
risks. In 2020, an estimated 619 million people worldwide were affected by LBP, with projections signifying a rise to 843 million by 2050. The construction sector in Ethiopia reports a high inci dence of work-related lower back pain, yet research quantifying this issue is scarce. The current study aims to assess the biomechanical impacts of different lifting techniques and weight combi nations on the lumbar spine to identify key factors contributing to lower back pain among con struction laborers. To achieve this, the study evaluated 210 scenarios involving various lifted
weights (0 to 125kg), lw - length of moment arm from lifted weight (0 to 0.5 meters), and α - angle between the extensor muscle force with body weight and lifted load (0°to 90°) using finite element analysis (FEA). The methodology involved converting 2D CT scan images into a 3D model for precise simulation of spinal stress under different conditions followed by model validation and FEA. The results revealed a maximum compressive force of 1419.71N when lifting 125kg at a 0° angle with a 0.5m moment arm and minimum compressive force of 126.196N at 90° angle with zero moment arm were obtained. The Von Mises stress result also ranged from 17.44MPa to 542.2MPa, showing peak stress at 0° angle and minimum at 90°. Increased weight and longer
moment arms significantly raised the stress, particularly affecting the facet joints of L3, L4 and L5 of lumbar spine with the anterior part of L5 lumbar spine exhibiting significant stress. Further
analysis indicated that directional deformation results of current study ranged from 0.0000629m to 0.001033m, with higher deformation associated with heavier loads and lower lifting angles.
Despite reduced stress at higher angles, improper lifting techniques still posed risks. This result indicates the importance of minimizing the distance between the body and the lifted weight, as
well as maintaining proper lifting posture as essential strategies for reducing compressive load on the lumbar spine and preventing injures. This study also highlights that heavier loads and upright posture increase compressive force, particularly in the L4-L5 region, posing a higher risk of long term injuries. To mitigate these risks, a proper lifting technique, ergonomic intervention and work place safety protocols that reduce compressive stress on the lumbar spine should be implemented. Reducing manual lifting needs, incorporating mechanical aids, and scheduling rest breaks can mit igate the risks. These measures are crucial for alleviating lumbar spine stress and preventing long term injuries, such as disc herniation.
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Keywords
Lower Back Pain, Construction Laborers, Weight, Finite Element Analysis