The objectives of this study are to present a 2-D optical method for measuring gross kinematics of porcine anterior column units (ACUs) exposed to swelling with no applied load, provide a detailed error analysis of the 2-D optical measurement technique, and present a 2-D radiographic technique for measuring the distribution of x-ray intensity through an axial slice of the disc. The 2-D optical technique was sufficient for detecting the flexion-extension behavior of the ACUs tested. The error analysis concluded that the use of a second camera to quantify out of plane movement of the specimen would greatly improve the accuracy of the measurement of angle. The 2-D radiographic technique provided limited information on changes in intradiscal material. It was also limited in its accuracy and dependability (i.e., only 5 out of 13 specimens provided radiographs suitable for this analysis). The results of this study indicate that a relationship might exist between the flexion-extension behavior observed from swelling and intradiscal shifts of matter. Further work is needed to confirm this relationship.

1.
Urban
,
J. P. G.
, and
McMullin
,
J. F.
,
1985
, “
Swelling Pressure of the Intervertebral Disc: Influence of Proteoglycan and Collagen Contents
,”
Biorheology
,
22
, pp.
145
157
.
2.
Urban
,
J. P. G.
, and
Maroudas
,
A.
,
1981
, “
Swelling of the Intervertebral Disc In Vitro
,”
Connect Tissue Res.
,
9
, pp.
1
10
.
3.
Johnstone
,
B.
et al.
,
1992
, “
The Fluid Content of the Human Intervertebral Disc—Comparison Between Fluid Content and Swelling Pressure Profiles of Discs Removed at Surgery and Those Taken Postmortem
,”
Spine
,
17
, pp.
412
416
.
4.
Bibby
,
S. R.
et al.
,
2001
, “
The Pathophysiology of the Intervertebral Disc
,”
Joint Bone Spine
,
68
(
6
), pp.
537
542
.
5.
White, A. A., and Panjabi, M. M., 1990, “Clinical Biomechanics of the Spine,” 2nd ed., Philadelphia: J. B. Lippincott Co.
6.
Berkson
,
M. H.
,
Nachemson
,
A.
, and
Schultz
,
A. B.
,
1979
, “
Mechanical Properties of Human Lumbar Spine Motion Segments—Part II: Responses in Compression and Shear; Influenc of Gross Morphology
,”
J. Biomech. Eng.
,
101
, pp.
53
57
.
7.
Kazarian
,
L. E.
,
1975
, “
Creep Characteristics of the Human Spinal Column
,”
Orthop. Clin. North Am.
,
6
(
1
), pp.
3
18
.
8.
Schultz
,
A. B.
et al.
,
1979
, “
Mechanical Properties of Human Lumbar Spine Motion Segments—Part I: Responses in Flexion, Extension, Lateral Bending, and Torsion
,”
J. Biomech. Eng.
,
101
, pp.
46
52
.
9.
Gunning
,
J. L.
,
Callaghan
,
J. P.
, and
McGill
,
S. M.
,
2001
, “
Spinal Posture and Prior Loading History Modulate Compressive Strength and Type of Failure in the Spine: A Biomechanical Study Using a Porcine Cervical Spine Model
,”
Clin. Biomech. (Bristol, Avon)
,
16
(
6
), pp.
471
480
.
10.
Shirazi-Adl
,
A.
,
1990
, “
Finite-Element Simulation of Changes in the Fluid Content of Human Lumbar Discs: Mechanical and Clinical Implications
,”
Spine
,
17
(
1
), pp.
206
212
.
11.
McNally
,
D. S.
, and
Adams
,
M. A.
,
1992
, “
Internal Intervertebral Disc Mechanics as Revealed by Stress Profilometry
,”
Spine
,
17
(
1
), pp.
66
73
.
12.
Andersson
,
G. B. J.
, and
Schultz
,
A. B.
,
1979
, “
Effects of Fluid Injection on Mechanical Properties of Intervertebral Discs
,”
J. Biomech.
,
12
, pp.
453
458
.
13.
Wren
,
T. A. L.
, and
Carter
,
D. R.
,
1998
, “
A Microstructural Model for the Tensile Constitutive and Failure Behavior of Soft Skeletal Connective Tissues
,”
J. Biomech. Eng.
,
120
, pp.
55
61
.
14.
Snook
,
S. H.
et al.
,
1998
, “
The Reduction of Chronic Nonspecific Low Back Pain Through the Control of Early Morning Lumbar Flexion: A Randomized Controlled Trial
,”
Spine
,
23
(
23
), pp.
2601
2607
.
15.
Thornton
,
W. E.
,
Hoffler
,
G. W.
, and
Rummel
,
J. A.
,
1977
, “
Anthropometric Changes and Fluid Shifts
,”
Biomedical Results From Skylab, NASA
,
pp.
330
338
.
16.
Styf
,
J. R.
et al.
,
1997
, “
Height Increase, Neuromuscular Function, and Back Pain During 6° Head-Down Tilt With Traction
,”
Aviat Space Environ. Med.
,
68
(
1
), pp.
24
29
.
17.
Wing
,
P. C.
et al.
,
1991
, “
Back Pain and Spinal Changes in Microgravity
,”
Orthop. Clin. North Am.
,
22
(
2
), pp.
255
262
.
18.
Krag
,
M. H.
et al.
,
1990
, “
Body Height Changes During Upright and Recumbent Posture
,”
Spine
,
15
(
3
), pp.
202
207
.
19.
Adams
,
M. A.
et al.
,
2000
, “
Effects of Backward Bending on Lumbar Intervertebral Discs
,”
Spine
,
25
(
4
), pp.
431
437
.
20.
Bass
,
E. C.
et al.
,
1997
, “
Frozen Storage Affects the Compressive Creep Behavior of the Porcine Intervertebral Disc
,”
Spine
,
22
(
24
), pp.
2867
2876
.
21.
Stokes
,
I.
, and
Greenapple
,
D. M.
,
1985
, “
Measurement of Surface Deformation of Soft Tissue
,”
J. Biomech.
,
18
(
1
), pp.
1
7
.
22.
Nachemson
,
A.
,
1960
, “
Lumbar Intradiscal Pressure
,”
Acta Ophthalmol. Scand. Suppl.
, Supplement
43
, pp.
9
104
.
23.
Nachemson
,
A.
,
1963
, “
The Influence of Spinal Movements on the Lumbar Intradiscal Pressure and on the Tensile Stresses in the Annulus Fibrosus
,”
Acta Orth
,
33
(
3
), pp.
183
207
.
24.
Callaghan
,
J. P.
, and
McGill
,
S. M.
,
1995
, “
Frozen Storage Increases the Ultimate Compressive Load of Porcine Vertebrae
,”
J. Orthop. Res.
,
13
(
5
), pp.
809
812
.
25.
Yingling
,
V. R.
, and
McGill
,
S. M.
,
1999
, “
Mechanical Properties and Failure Mechanics of the Spine Under Posterior Shear Load: Observations From a Porcine Model
,”
J. Spinal Disord.
,
12
(
6
), pp.
501
508
.
26.
Yingling
,
V. R.
, and
McGill
,
S. M.
,
1999
, “
Anterior Shear of Spinal Motion Segments
,”
Spine
,
24
(
18
), pp.
1882
1889
.
27.
Yingling
,
V. R.
,
Callaghan
,
J. P.
, and
McGill
,
S. M.
,
1999
, “
The Porcine Cervical Spine as a Model of the Human Lumbar Spine: An Anatomical, Geometric, and Functional Comparison
,”
J. Spinal Disord.
,
12
(
5
), pp.
415
423
.
28.
Smeathers
,
J. E.
, and
Joanes
,
D. N.
,
1988
, “
Dynamic Compressive Properties of Human Lumbar Intervertebral Joints: A Comparison Between Fresh and Thawed Specimens
,”
J. Biomech.
,
21
(
5
), pp.
425
433
.
29.
Pflaster
,
D. S.
et al.
,
1997
, “
Effects of Test Environment on Intervertebral Disc Hydration
,”
Spine
,
22
(
2
), pp.
133
139
.
30.
Adams
,
M. A.
, and
Hutton
,
W. C.
,
1983
, “
The Effects of Posture on the Fluid Content of Lumbar Intervertebral Discs
,”
Spine
,
8
(
6
), pp.
665
671
.
31.
Galante
,
J. O.
,
1967
, “
Tensil Properties of the Human Lumbar Annulus Fibrosus
,”
Acta Ophthalmol. Scand. Suppl.
,
100
, pp.
5
91
.
32.
Wing
,
P.
et al.
,
1992
, “
Diurnal Changes in the Profile Shape and Range of Motion of the Back
,”
Spine
,
17
(
7
), pp.
761
766
.
33.
Wilke
,
H. J.
et al.
,
1999
, “
New in Vivo Measurements of Pressure in the Intervertebral Disc in Daily Life
,”
Spine
,
24
(
8
), pp.
755
762
.
You do not currently have access to this content.