The technique used to incise the disc during discectomy may play a role in the subsequent healing and change in biomechanical stiffness of the disc. Several techniques of lumbar disc annulotomy have been described in clinical reports. The purpose of this paper was to study the influence of annulotomy technique on motion segment stiffness using a finite element model. Four incision methods (square, circular, cross, and slit) were compared. The analyses showed that each of the annular incisions produced increase in motions under axial moment loadings with circular incision producing the largest change in the corresponding rotational motion. Under shear loading mode, cross and slit-type annular incisions produced slightly larger changes in the principal motions of the disc than square and circular incisions. All other incision types considered in the current study produced negligibly small increase in motion under rest of the loading conditions. In addition to annulotomy, when nucleotomy was also included in the analyses, once again cross and slit incisions produced larger change in motion under shear loading mode as compared to the other two incision types. A comparison between the four types of annular incisions showed that cross incision produced an increase in motion larger than those produced by the other three incisions under flexion/extension and lateral moment loading and both shear force loadings. Circular incision produced the largest increase in motion under axial moment load in comparison to those produced by square, cross, and slit incisions. Sagittal plane symmetry was influenced by the incision injury to the motion segment leading to coupled motions as well as increased facet loads. From the study it can be concluded that the increase in flexibility of the disc due to annulotomy depends on the type of annulotomy, and the annulotomy also produce asymmetrical deformations leading to increased facet loading.

1.
Brinckmann
,
P.
, and
Horst
,
M.
,
1985
, “
The Influence of Vertebral Body Fracture, Intradiscal Injection and Partial Discectomy on the Radial Bulge and Height of Human Lumbar Discs
,”
Spine
,
10
, pp.
138
145
.
2.
Brinckmann
,
P.
,
1986
, “
Injury of the Annulus Fibrosus and Disc Protrusions—An In Vitro Investigation on Human Lumbar Discs
,”
Spine
,
11
, pp.
149
153
.
3.
Seroussi
,
R.
,
Krag
,
M.
,
Muller
,
D.
, and
Pope
,
M.
,
1989
, “
Internal Deformations of Intact and Denucleated Human Lumbar Discs Subjected to Compression, Flexion and Extension Loads
,”
J. Orthop. Res.
,
l7
, pp.
122
131
.
4.
Shia
,
M.
,
Takeuchi
,
T. Y.
,
Wittenberg
,
R. H.
,
White
,
A. A.
, and
Hayes
,
W. C.
,
1994
, “
A Comparison of the Effects of Automated Percutaneous Diskectomy and Conventional Diskectomy on Intradiscal Pressure, Disk Geometry, and Stiffness
,”
J. Spinal Disord.
,
17
, pp.
317
325
.
5.
Panjabi
,
M. M.
,
Krag
,
M. H.
, and
Chung
,
T. Q.
,
1984
, “
Effects of Disc Injury on Mechanical Behavior of the Human Spine
,”
Spine
,
9
, pp.
707
713
.
6.
Goel
,
V. K.
,
Nishiyama
,
K.
,
Weinstein
,
J. N.
, and
Liu
,
Y. K.
,
1986
, “
Mechanical Properties of Lumbar Spinal Motion Segments as Affected by Partial Disc Removal
,”
Spine
,
11
, pp.
1008
1012
.
7.
Holones, H. E., and Rothman, R. H., 1983, “Technique of Lumbar Laminectomy,” AAOS Instruction Course Lecture, C. V. Mosby Co., St. Louis, MO, Vol. 34, pp. 200–207.
8.
Long, D. M., 1987, “Laminotomy for Lumbar Disc Disease,” Lumbar Discectomy and Laminectomy, R. G, Watkins and J. S. Collis, eds., Aspen Publishers, Rockville, MD, pp. 173–178.
9.
Williams, R. W., 1988, “Post-Surgical Lumbar Scarring: A Study of Surgical Morbidity,” Lumbar Discectomy and Laminectomy, R. G. Watkins and J. S. Collis, eds., Aspen Publishers, Rockville, MD, pp. 253–264.
10.
Either
,
D. B.
,
Cain
,
J. E.
,
Yaszemski
,
M. J.
,
Glover
,
J. M.
,
Klucznik
,
R. P.
,
Pyka
,
R. E.
, and
Lauerman
,
W. C.
,
1994
, “
The Influence of Annulotomy Selection on Disc Competence—A Radiographic, Biomechanical, and Histologic Analysis
,”
Spine
,
19
, pp.
2071
2076
.
11.
Ahlgren
,
B. D.
,
Vasavad
,
A.
,
Browser
,
R. S.
,
Lydon
,
C.
,
Herkowitz
,
H. N.
, and
Panjabi
,
M. M.
,
1994
, “
Annular Incision Technique on the Strength and Multidirectional Flexibility of the Healing Intervertebral Disc
,”
Spine
,
19
, pp.
948
954
.
12.
Shirazi-Adl
,
S. A.
,
Shrivastava
,
S. C.
, and
Ahmed
,
A. M.
,
1983
, “
Stress Analysis of the Lumbar Disc-Body Unit in Compression—A Three Dimensional Nonlinear Finite Element Study
,”
Spine
,
l9
, pp.
120
134
.
13.
Kim, Y. E., and Goel, V. K., 1988, “Biomechanics of Chemonucleolysis,” Computational Methods in Bioengineering, R. L. Spilker and B. R. Simon, eds., ASME, New York, pp. 461–471.
14.
Natarajan
,
R. N.
,
Andersson
,
G. B. J.
,
Patwardhan
,
A. G.
, and
Andriacchi
,
T. P.
,
1999
, “
Study of Effect of Graded Facetectomy on Changes in Lumbar Motion Segment Torsional Flexibility Using Three Dimensional Continuum Contact Representation for Facet Joints
,”
ASME J. Biomech. Eng.
,
121
, pp.
215
221
.
15.
Natarajan
,
R. N.
, and
Andersson
,
G. B. J.
,
1999
, “
The Influence of Lumbar Disc Height and Cross-Sectional Area on the Mechanical Response of the Disc to Physiological Loading
,”
Spine
,
24
, pp.
1873
1881
.
16.
ADINA, R&D Inc., Watertown, MA 02172, USA.
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