Loads in the spinal structures during lifting: development of a three-dimensional comprehensive biomechanical model

Abstract

Epidemiological studies have shown that loads imposed on the human spine during daily living play a significant role in the onset of low back pain. The loads applied to the lumbar spine are shared by a number of structures: muscles; posterior elements, including facets and ligaments; and the disc of a ligamentous motion segment. In vivo, it is not practical to determine forces in these structures using experimental techniques. Biomechanical models, based on an optimization technique of electromyographic activities of the trunk muscles, have been proposed to predict forces in the load transmitting structures. The mathematical models reported in the literature are based on information collected from a wide variety of sources, of which the subject that takes part in the experiment is only one. The present study describes techniques developed in our laboratory to collect from the subjects themselves all the data needed for the formulation of a biomechanical model. The results demonstrated that back lifting with 0 N (no load), 90 N, and 180 N in the hands created maximum external flexion moments respectively of 109.6 Nm, 137.9 Nm, and 161.7 Nm, at the L3-4 disc level. The corresponding external axial compression forces on the disc were 469.5 N, 511.8 N, and 601.5 N. The predicted disc compression varied from 3.4 to 5.0 times the body weight. In comparison to the static lifting mode, the dynamic lifting task caused an increase in the disc compression force ranging from 15.8% to 39.4% depending on the load being lifted (e.g., 3256 N for the dynamic mode vs. 2516 N for the static mode when the subject lifted 90 N). The salient features of the entire protocol developed by the authors and the need for further improvements are also presented.

Effect of Supplemental Translaminar Facet Screw Fixation on the Stability of Stand-Alone Anterior Lumbar Interbody Fusion Cages Under Physiologic Compressive Preloads

“…The compressive forces on the interbody cages are thought to be generated by anulus fibrosus tension resulting from disc space distraction, external loads, and trunk muscle forces. In vivo compressive load on the human lumbar spine during supine and recumbent postures is estimated to be 200 N to 300 N, whereas during standing and walking activities, the lumbar spine segments are subjected to estimated loads of up to 1200 N. [25][26][27] It follows that when measuring the stabilizing effect of interbody constructs, the experimental model should involve application of compressive preloads of similar physiologic magnitudes to the lumbar spine.…”

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

“…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.…”

A novel method to estimate the stiffness of the equine back

“…Modeling has become a commonly accepted and widely used means for studying the behavior of biomechanical systems (Yoganandan et al, 2001). Using surface EMG and locomotion data, Han et al (1995) have formulated such a model for the human spine. Van den Bogert et al (1989) have developed models of the whole horse built with different numbers of rigid segments, however these are not realistic enough for in-depth analysis of back motion.…”