The biomechanics of vibration and low back pain

Abstract

This work is a review of the mechanical factors related to low back pain production in a vibration environment. The sitting posture is an extreme orientation for the lumbar intervertebral disc that 1) increases its internal pressure, 2) increases its anteroposterior shear flexibility, while: 3) decreasing its resistance to buckling instability and 4) stressing the posterior region of the disc. Vibration is an additional mechanical stressor. Several studies suggest that the following preventive measures be taken to reduce the risk of low back pain due to driving: 1) minimize the vibration reaching the driver, 2) avoid lifting or bending immediately following driving, and 3) walk around for a few minutes following driving.

Dynamic stiffness and damping of human intervertebral disc using axial oscillatory displacement under a free mass system

“…The main one is that fluid flow causes variations in volume [2, 7,21] and in the mechanical properties of the disc [23]. Maintaining hydration during the experiments is therefore important [1,3,16,24].…”

“…They are linked to lifestyle and in particular to the widespread operation of automobiles [3, 18,24], heavy industrial machinery and buses, and to the effort involved in lifting [9]. Many authors have studied back complaints, and have foregrounded the influence of vibrations [7] as a source of these complaints.…”

“…Many authors have studied back complaints, and have foregrounded the influence of vibrations [7] as a source of these complaints. To improve vehicle seats and to filter vibrations better [24], it is planned to design biomechanical models of the human body. To achieve these models, it is necessary to know the mechanical properties of the different structures of the human body, and we have focused first on the intervertebral disc.…”

Rheumatic effects of vibration at work

“…As evidenced by cadaver experiments, mechanical damage and interference with tissue nutrition may lead to degeneration and microfractures of the vertebral endplates, increased intradiscal pressure, and rupture of disc fibres [66,67], with resultant development disc herniation [68,69]. Additionally, electromyographic studies have shown than WBV can induce fatigue in the paravertebral muscles of the lower back [65]. Thus, a degree of biological plausibility exists for a causal relationship between WBV and low back complaints, assuming that fatigue is a cause of back discomfort.…”

“…When WBV is measured on vehicle seating, it tends to show peaks of acceleration at frequencies of 2-6 Hz, which corresponds to the resonant frequency of the lumbar spine in a seated subject exposed to vertical vibration [64,65]. It is thought that such resonance can cause large relative displacements between the lumbar vertebrae, with extra compressive load and shear stress on tissues of the spine.…”