The role of the middle lumbar fascia on spinal mechanics: a human biomechanical assessment

Introduction - The aims of this study were to test the effect of fascial tension on lumbar segmental axial rotation and lateral flexion and the effect of the angle of fascial attachment. Tension in the middle layer of lumbar fascia has been demonstrated to affect mechanical properties of lumbar segmental flexion and extension in the neutral zone. However, the effect of tension on segmental axial rotation and lateral flexion has not been investigated. Methods - Seven unembalmed lumbar spines were divided into segments and mounted for testing. A 6 degree of freedom robotic testing facility was used to displace the segments in each anatomical plane (flexion-extension, lateral bending and axial rotation) with force and moment data recorded by a load cell positioned beneath the test specimen. Tests were performed with and without a 20N fascia load and the subsequent forces and moments were compared. In addition, forces and moments were compared when the specimens were held in a set position and the fascia loading angle was varied. Results - A fascial tension of 20N had no measurable effect on the forces or moments measured when the specimens were displaced in any plane of motion (p>0.05). When 20N of fascial load were applied to motion segments in a set position small segmental forces and moments were measured. Changing the angle of the fascial load did not significantly alter these measurements. Conclusions - Application of a 20N fascial load did not produce a measureable effect on the mechanics of a motion segment even though it did produce small measurable forces and moments on the segments when in a fixed position. Results from the current study are inconsistent with previous studies, suggesting that further investigation using multiple testing protocols and different loading conditions is required to determine the effects of fascial loading on spinal segment behaviour.