Kinematic response of lumbar functional spinal units to axial torsion with and without superimposed compression and flexion/extension

Abstract

Experimental data suggest that lumbar torsion contributes to lumbar disc degenerative changes, such as instability, spondylolisthesis and spinal canal stenosis. However, some basic mechanical characteristics of the lumbar spine under torsional loading have not yet been reported in detail. For example, the function of the facet joints under combined mechanical loads such as torsion with superimposed flexion or extension postures is an area of interest about which little biomechanical data have been reported. In this study, the kinematic response to axial torsion with superimposed axial compression (200 N), compression-flexion (3 and 6 Nm) and compression-extension (3 and 6 Nm) was investigated in 10 cadaveric lumbar functional spinal units. Range of motion (ROM), and helical axes of motion (HAM), were analyzed. There was no difference in ROM between no preload, pure compressive and flexion-compression preload conditions. The ROM was significantly reduced by both extension-compression preload conditions (11% reduction for 3 Nm and 19% reduction for 6 Nm of extension) compared to the pure compressive preload. For no preload, the average HAM position in the transverse plane of the intervertebral disc was near the posteriormost part of the disc and located laterally on the side contralateral to the applied torsional moment. In the transverse plane, the HAM position showed a discrete trend towards the posterior part of the specimens during extension. Kinematic data were visualized using computer animation techniques and CT-based reconstructions of the respective specimens. This information may be used for identifying and characterizing physiologic and pathologic motion and for specifying conservative and surgical treatment concepts and, thus, may find application to identifying indications for spinal fusion or in evaluating the effect of future semi-flexible instrumentation.

Determination of torque-limits for human and cat lumbar spine specimens during displacement-controlled physiological motions

“…This may have been due to anatomical differences between the two species. In humans, pure axial rotation ceases when the sagittally-oriented facet joints come into contact [28], while the kinematics of lumbar joint segments have not been studied extensively in cats. Lumbar facets in cats have slightly different orientations, with the superior and inferior facets facing medial-posteriorly and lateralanteriorly, respectively [29].…”

How do spinal segments move?

“…But for reasons of physics, such data did not give any indication for segment kinematics. One held a priori that the spinal kinematics would be geometrically simple since the ROM amounted to only few degrees: The upper segment would rotate in relation to the lower around a segmentally fixed rotational axis (Panjabi et al, 1981; or would helically move around a fixed helical axis of motion, the HAM (Zhu et al, 2007;Haberl et al, 2004;Niosi et al, 2006). The position of HAM was calculated from two measured positions of the moved vertebra, which differed nearly by ROM.…”

The relationship between bowling action classification and three-dimensional lower trunk motion in fast bowlers in cricket

“…Chosa et al (2004) found that unilateral pars interarticularis stress was greatest under combinations of compression with lumbar extension, compression with lumbar side-flexion to the same side, and compression with lumbar rotation to the opposite side. Further, it is known that the available ROM of lumbar axial rotation is reduced when the spine is in end range extension (Haberl et al, 2004, Burnett et al, 2006, therefore implying increased stiffening of the spine when it is positioned near the limits of its physiological ROM. Panjabi (1992) terms this zone of high stiffness towards end range the "elastic zone of motion".…”