Mechanical response of lumbar spine motion segments: flexibilities, nuclear pressures, posterior element influences.
Berkson-M; Nachemson-AL; Schultz-AB; Warwick-DN; Galante-JO
NIOSH 1977; :1-486
A NIOSH sponsored study was conducted on the mechanical response of lumbar spine motion segments in relation to flexibility, nuclear pressures and posterior element influences. Sixteen fresh, nondegenerate cadaver lumbar spine motion segments from 11 spines of age 35 to 60 years were mounted on a test fixture. Following a compressive preload of 400n, motion segments were subjected to flexion, extension and lateral bending moments up to 14.5Nm, torsional moments up to 20.4Nm, and anteroposterior and lateral shear forces up to 250N. Forces were applied so as to simulate an in-vivo range of loads. The translation and rotations that resulted from the series of moments were measured and the test sequence was repeated after removal of posterior elements. It was found that the posterior elements did not play a major role in segment mechanical behavior; removal of the posterior elements resulted in 50% increase in flexion, extension, lateral bending and shear, and a 110% increase in torsion. Under the 400N compressive load with posterior elements intact, nuclear pressure had a mean value of 1.46 times the applied load divided by the disc cross-sectional area. Results indicate that nuclear pressure can be related to the magnitude of the load the motion segment experiences when the character of the load acting on the motion is known or its motion is carefully observed.
NIOSH-Grant; Physiology; Physiological-testing; Musculoskeletal-system-disorders; Force
Materials Engineering, University of Illinois Department of Materials Engineering, Box 4348, Chicago, IL 60680
Low Back Disorders; Disease and Injury; Musculoskeletal-system-disorders;
Proceedings of the Twenty-Third Annual ORS (Paper presented at Las Vegas, Nevada, February 1-3, 1977), NIOSH Grant No. R01-OH-00514 page T175
University of Illinois Chicago Circle, Chicago, Illinois