Shear mechanical properties of human lumbar annulus fibrosus

Journal of Orthopaedic Research - Tập 17 Số 5 - Trang 732-737 - 1999
James C. Iatridis1, Sanjay Kumar2, Robert J. Foster3, Mark Weidenbaum3, Van C. Mow3
1Department of Mechanical Engineering, University of Vermont, Burlington 05405-0084, USA.
2Department of Orthopaedic Surgery, Mayo Clinic, Rochester, Minnesota, New York, U.S.A.
3Orthopaedic Research Laboratory, Columbia University, New York, New York, U.S.A.

Tóm tắt

AbstractFunction, failure, and remodeling of the intervertebral disc are all related to the stress and strain fields in the tissue and may be calculatd by finite element models with accurate material properties, realistic geometry, and appropriate boundary conditions. There is no comprehensive study in the literature investigating the shear material properties of the annulus fibrosus. This study obtained shear material properties of the annulus fibrosus and tested the hypothesis that these properties are affected by the amplitude and frequency of shearing, applied compressive stress, and degenerative state of the tissue. Cylindrical specimens with an axial orientation from seven nondegenerated and six degenerated discs were tested in torsional shear under dynamic and static conditions. Frequency sweep experiments over a physiological range of frequencies (0.1‐100 rad/sec) at a shear strain amplitude of 0.05 rad were performed under three different axial compressive stresses (17.5, 25, and 35 kPa). At the largest compressive stress, shear strain sweep experiments (strain amplitude range: 0.005‐0.15 rad at a frequency of 5 rad/sec) and transient stress‐relaxation tests (shear strain range: 0.02‐0.15 rad) were performed. The annulus fibrosus material was less stiff and more dissipative at larger shear strain amplitudes, stiffer at higher frequencies of oscillation, and stiffer and less dissipative at larger axial compressive stresses. The dynamic shear modulus, |G*|, had values ranging from 100 to 400 kPa, depending on the experimental condition and degenerative level. The shear behavior was also predominantly elastic, with values for the tangent of the phase angle (tanδ) ranging from 0.1 to 0.7. The annulus material also became stiffer and more dissipative with degenerative grade; however, this was not statistically significant. The results indicated that nonlinearities, compression/shear coupling, intrinsic viscoelasticity, and, to a lesser degree, degeneration all affect the shear material behavior of the annulus fibrosus, with important implications for load‐carriage mechanisms in the intervertebral disc. These material complexities should be considered when choosing material constants for finite element models.

Từ khóa


Tài liệu tham khảo

10.1097/00007632-199512150-00010

Andersson GBJ, 1996, Low Back Pain: A Scientific and Clinical Overview, 7

10.1097/00007632-199401001-00017

Bodine AJ, 1982, Viscoelastic shear modulus of the human intervertebral disc, Trans Orthop Res Soc, 7, 237

Fujita Y, 1996, Anisotropic shear behavior of the annulus fibrosus: effect of harvest site and tissue prestrain, Trans Orthop Res Soc, 21, 271

10.3109/ort.1967.38.suppl-100.01

10.1097/00007632-199503150-00010

10.1002/jor.1100150224

10.1016/S0021-9290(98)00046-3

Krag MH, 1993, Effect of denucleation and degeneration grade on intervertebral disc stress relaxation, Trans Orthop Res Soc, 18, 207

10.1097/00007632-199201000-00011

10.1097/00007632-198802000-00008

10.1148/radiology.152.1.6729099

Mow V, 1992, Knee Meniscus: Basic and Clinical Foundations, 37

10.2106/00004623-196446050-00012

10.1097/00007632-199402000-00001

10.1016/0021-9290(93)90019-B

10.1016/0021-9290(89)90050-X

10.1016/0268-0033(89)90017-X

10.1097/00007632-199406000-00002

10.1115/1.3138575

10.1097/00007632-199401001-00020

10.1097/00007632-199005000-00012

10.1097/00007632-198802000-00009

10.1097/00007632-199904150-00005

Zhu W, 1994, Anisotropic viscoelastic shear properties of bovine meniscus, Clin Orthop, 306, 34

10.1002/jor.1100110602

Thông tin
Thông tin xuất bản

Journal of Orthopaedic Research

Tập 17 Số 5

732-737

Thông tin tác giả