Abstract

Lower back pain frequently occurs in modern humans for complex reasons. Some aspects of the mechanism are still not fully understood. The primary aim of this research is to analyze the causes of swelling, inflammation and pain in the psoas muscles resulting from intervertebral disc degeneration (L3-L4) using the biomechanical theorem of hoop stress. The secondary aim is to convert these stress data into a pain index using granular computing. We organized and analyzed the psoas muscle stress (hoop stress) across different genders, weights, bending postures and age groups. The pain factors are divided into 10 levels. Each patient's pain factor and condition are assessed after a medical examination. A total of 1400 patients are included in this research. The results show that up to 20 times the body weight acts on the psoas muscles during lumbar flexion. It also indicates that the pain factor (hoop stress) at the L4-L5 intervertebral disc is about 1.3 times larger than at L3-L4 for both males and females. 

Keywords: Psoas muscles, Hoop stress, Intervertebral disc degeneration, Granular computing, Pain factor