Keywords
spinal pedicle - multidetector CT scan - morphometry - lumbar spine
Introduction
Backache and neck pain has been the scourge of mankind ever since it assumed the erect
posture. The pain has troubled patients and treating doctors alike. Pinpointing the
cause of backache and neck pain and treating it successfully has been their constant
endeavor.
The sole bridge between the posterior, middle, and anterior columns is pedicle. Hence,
pedicle screws traverse all three columns and can rigidly stabilize both the ventral
and dorsal aspects of the spine. Performing pedicle screw fixation is technically
challenging.[1] The key to successful surgery involves possessing clear knowledge of intracanal
anatomy and the location of the pedicle.[2] A detailed knowledge of pedicle size and dimensions is crucial while using the pedicle
to gain hold and strength of the vertebra. The sizes of the screws used in surgery
must take pedicle dimensions into consideration.[3]
Intraoperative complications for the pedicle screw fixation include screw misdirection
and pedicle fracture.[4] The stability of the pedicle screw and its pullout strength depend on the integrity
of the pedicle and the vertebral body even though larger screw sizes are preferred
as they are stronger and give better results. The deciding factor in screw selection
is the minimum width of the pedicle.
The morphometric characteristics of the vertebral pedicle are valuable for preoperative
procedure planning and in the design and manufacture of pedicle screws.[5] Knowledge of such morphometric characteristics is important for the surgeon to prevent
injuries to the pedicle cortex, meninges, nerve roots, joint facets, viscera or adjacent
vascular structures due to misplacement or improper orientation of the screws.[6]
[7]
Previous studies have resorted to the use of axial slices in CT to determine the cortical
and endosteal pedicle widths of lumbar pedicles. However, recently, it has been established
that due to the oval morphology of the lumbar pedicle in the coronal section and the
normal vertebral pedicle inclination in relation to the horizontal plane, the pedicle
width results obtained from these studies may not match the actual minimum pedicle
diameter and may lead to inadequate identification of the morphometric features of
the pedicle.[8]
The present study was done at our tertiary care institute to assess the spinal pedicle
morphometry (pedicle width, height and angulation) of lumbar spine using multidetector
CT (MDCT) scan, so as to develop a standard value for the Indian population.
Aim
To study the morphometry of lumbar spine pedicles for neurosurgical intervention by
using noninvasive MDCT, in order to standardize the size of pedicle screws at various
lumbar levels and across different age groups.
Objectives
-
To study the spinal pedicle width and height of lumbar spine, using MDCT, among the
Indian population.
-
To study the spinal pedicle angulation of lumbar spine, using MDCT, among the Indian
population.
Materials and Methods
a) Patient Population
After being approved by the ethical committee board at our institution, we prospectively
included patients who were referred to us for lumbar spine pedicle morphology evaluation
using 16 slice scanner (Brilliance 16, Philips; Netherlands) at our institution over
a period of 2 years, extending from May 2017 to May 2019.
A total of 321 cases were included in the study. The inclusion of cases was on the
basis of referral from neurosurgical outpatient and patients who were planned for
surgery. All these patients were scanned after obtaining an informed consent, and
all patients who had undergone noncontrast CT abdomen were also included in the dataset.
All the cases of lumbar spine operated or fracture were excluded from the study.
b) Data Collection
Data was evaluated and reconstructed at our CT workstation as per the protocol. The
study was done at our tertiary care hospital set up to assess the spinal pedicle morphometry
(pedicle width, height and angulation) of lumbar spine, so as to develop a standard
value for the Indian population. The aim was to standardize the size of pedicle screws
that is required at various lumbar vertebra levels and vary it as per the sex and
age of the patient. All patients who presented with features of spondylolysis on radiograph
and planned for pedicle fixation screws were included in the study. Each scan was
evaluated by a radiologist with experience of more than 10 years after being evaluated
by a final-year radiology resident who was well-trained to calculate the morphometric
values of pedicle.
The transverse diameter and angulation of each side of pedicle was measured as depicted
in [Figs. 1] and [2]. The height of each pedicle and the sagittal angulation was measured as depicted
in [Figs. 3] and [4]. For sagittal angulation, on each side, images were reconstructed in oblique sagittal
plane, where the maximum height of pedicle was observed. This was done to provide
the most anatomic orientation to the pedicle in relation to the vertebral body.
Fig. 1 Showing the measurement of inner cancellous axial diameter of L2 vertebra.
Fig. 2 Showing the axial angle formed by the longitudinal trajectory of the right- and left-sided
pedicles at the axis of the L2 vertebra.
Fig. 3 Showing the inner cancellous pedicle height of L2 vertebra.
Fig. 4 Showing the pedicle body lateral angulation of the right sided pedicle of the L2
vertebra.
The data was taken from the workstation. Comparison was made separately between each
subgroup.
Statistical Method
Descriptive analysis was performed by mean and standard deviation for quantitative
variables, ad frequency and proportion for categorical variables. Data was also represented
using appropriate diagrams like bar diagram, pie diagram, and box plots.
Results
Among the study population (n = 321), 34 (10.6%) participants were aged between 10 to 20 years, 49 (15.30%) participants
were aged between 21 to 30 years, 44 (13.7%) participants were aged between 31 to
40 years, 51 (15.9%) participants were aged between 41 to 50 years, 54 (16.8%) participants
were aged between 51 to 60 years, 45 (14%) participants were aged between 61 to 70
years, 30 (9.3%) participants were aged between 71 to 80 years, and 14 (4.4%) participants
were aged between 81 to 90yrs. Our study comprised of 67.6% male and 32.4% female
patients.
In the 10 to 20 Years Age Group
In the 10 to 20 Years Age Group
In the age group of 10 to 20 years (n = 34), the mean axial diameter of the pedicle
varied from 6.18 to 11.46 mm on the right and 5.81 to 11.67 mm on the left side. The
mean height of pedicle varied from 9.42 to 9.26 mm on the right and 9.22 to 9.14 mm
on the left side [Table 1].
Table 1
Descriptive analysis of pedicle diameter (mm) and height (mm) in study population
(N = 34)
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
6.18 ± 0.62
|
5.96
|
6.39
|
9.42 ± 0.2
|
9.34
|
9.49
|
|
L2 right
|
5.98 ± 0.58
|
5.78
|
6.18
|
9.82 ± 0.22
|
9.75
|
9.90
|
|
L3 right
|
8.21 ± 0.65
|
7.99
|
8.44
|
9.75 ± 0.16
|
9.70
|
9.81
|
|
L4 right
|
8.43 ± 0.1
|
8.39
|
8.46
|
8.11 ± 0.16
|
8.05
|
8.16
|
|
L5 right
|
11.46 ± 0.3
|
11.36
|
11.57
|
9.26 ± 0.22
|
9.18
|
9.33
|
|
L1 left
|
5.81 ± 0.48
|
5.64
|
5.98
|
9.29 ± 0.21
|
9.22
|
9.36
|
|
L2 left
|
5.65 ± 0.42
|
5.510
|
5.80
|
10.36 ± 0.25
|
10.27
|
10.44
|
|
L3 left
|
7.92 ± 0.65
|
7.70
|
8.15
|
8.94 ± 0.37
|
8.81
|
9.07
|
|
L4 left
|
8.26 ± 0.16
|
8.21
|
8.32
|
7.67 ± 0.33
|
7.55
|
7.79
|
|
L5 left
|
11.67 ± 0.27
|
11.58
|
11.76
|
9.32 ± 0.5
|
9.14
|
9.49
|
In the age group of 10 to 20 years (n = 34), the mean transverse angulation of the
pedicle varied from 21.27 to 34.69 degrees on the right and 20.9 to 35.29 degrees
on the left side. The mean sagittal angulation of pedicle varied from 19.02 to 18.56
degrees on the right and 18.38 to 18.69 degrees on the left side [Table 2].
Table 2
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal (degree)
in study population (N = 34)
|
Parameter
|
Axial mean ± SD (mm)
|
95% CI
|
Lateral mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
21.27 ± 1.07
|
20.90
|
21.64
|
19.02 ± 0.53
|
18.84
|
19.20
|
|
L2 right
|
20.99 ± 0.82
|
20.70
|
21.28
|
18.9 ± 0.81
|
18.61
|
19.18
|
|
L3 right
|
24.4 ± 1.05
|
24.03
|
24.76
|
18.39 ± 1.33
|
17.93
|
18.86
|
|
L4 right
|
26.69 ± 0.7
|
26.45
|
26.93
|
17.69 ± 1.01
|
17.33
|
18.04
|
|
L5 right
|
34.69 ± 0.37
|
34.56
|
34.81
|
18.56 ± 1.92
|
17.89
|
19.23
|
|
L1 left
|
20.92 ± 1.05
|
20.55
|
21.28
|
18.38 ± 0.86
|
18.08
|
18.68
|
|
L2 left
|
21.39 ± 0.64
|
21.16
|
21.61
|
17.87 ± 1.37
|
17.39
|
18.35
|
|
L3 left
|
23.83 ± 1.07
|
23.45
|
24.20
|
18.03 ± 1.67
|
17.45
|
18.61
|
|
L4 left
|
26.27 ± 0.95
|
25.94
|
26.60
|
17.63 ± 1.02
|
17.27
|
17.98
|
|
L5 left
|
35.29 ± 0.24
|
35.20
|
35.37
|
18.69 ± 1.58
|
18.14
|
19.24
|
In the 21 to 30 Years Age Group
In the 21 to 30 Years Age Group
In the age group of 21 to 30 years (n = 49), the mean axial diameter of the pedicle
varied from 5.59 to 11.41 mm on the right and 5.54 to 11.63 mm on the left side. The
mean height of pedicle varied from 10.7 to 9.13 mm on the right and 10.45 to 8.99
mm on the left side [Table 3].
Table 3
Descriptive analysis of pedicle diameter and height in study population (N = 49)
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
5.59 ± 0.91
|
5.33
|
5.85
|
10.7 ± 1.3
|
10.33
|
11.07
|
|
L2 right
|
5.58 ± 1.13
|
5.25
|
5.90
|
10.48 ± 1.05
|
10.18
|
10.78
|
|
L3 right
|
6.92 ± 1.28
|
6.55
|
7.29
|
9.99 ± 0.9
|
9.73
|
10.25
|
|
L4 right
|
8.08 ± 1.35
|
7.69
|
8.47
|
9.12 ± 1.12
|
8.80
|
9.44
|
|
L5 right
|
11.41 ± 0.36
|
11.02
|
11.80
|
9.13 ± 1.02
|
8.84
|
9.42
|
|
L1 left
|
5.54 ± 0.93
|
5.27
|
5.80
|
10.45 ± 1.18
|
10.11
|
10.79
|
|
L2 left
|
5.62 ± 1.02
|
5.33
|
5.91
|
10.35 ± 1.06
|
10.05
|
10.65
|
|
L3 left
|
7.01 ± 1.1
|
6.7
|
7.33
|
10.04 ± 0.82
|
9.80
|
10.27
|
|
L4 left
|
8.08 ± 1.19
|
7.74
|
8.42
|
9.16 ± 1.31
|
8.78
|
9.54
|
|
L5 left
|
11.63 ± 0.35
|
11.24
|
12.01
|
8.99 ± 1.07
|
8.68
|
9.30
|
In the age group of 21 to 30 years (n = 49), the mean transverse angulation of the
pedicle varied from 22.47 to 34.66 degrees on the right and 22.37 to 34.75 degrees
on the left side. The mean sagittal angulation of pedicle varied from 21.13 to 19.94
degrees on the right and 21.01 to 19.65 degrees on the left side [Table 4].
Table 4
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal in study
population (N = 49)
|
Parameter
|
Axial mean ± SD
|
95% CI
|
Lateral mean ± SD
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
22.47 ± 1.31
|
22.10
|
22.85
|
21.13 ± 2.41
|
20.43
|
21.82
|
|
L2 right
|
22.91 ± 1.35
|
22.52
|
23.29
|
20.43 ± 1.92
|
19.88
|
20.98
|
|
L3 right
|
24.93 ± 1.61
|
24.47
|
25.39
|
21 ± 3.38
|
20.03
|
21.97
|
|
L4 right
|
28.44 ± 1.55
|
27.99
|
28.88
|
19.67 ± 2.82
|
18.86
|
20.48
|
|
L5 right
|
34.66 ± 2.29
|
34.00
|
35.32
|
19.94 ± 2.77
|
19.15
|
20.74
|
|
L1 left
|
22.37 ± 1.36
|
21.98
|
22.76
|
21.01 ± 2.45
|
20.31
|
21.71
|
|
L2 left
|
22.81 ± 1.23
|
22.46
|
23.16
|
20.38 ± 2.09
|
19.78
|
20.98
|
|
L3 left
|
24.91 ± 1.59
|
24.45
|
25.37
|
21.22 ± 3.5
|
20.22
|
22.23
|
|
L4 left
|
28.42 ± 1.65
|
27.94
|
28.89
|
19.29 ± 2.93
|
18.45
|
20.13
|
|
L5 left
|
34.75 ± 2.22
|
34.12
|
35.39
|
19.65 ± 3.03
|
18.77
|
20.52
|
In the Age Group of 31 to 40 Years
In the Age Group of 31 to 40 Years
In the age group of 31 to 40 years (n = 44), the mean axial diameter of the pedicle
varied from 5.89 to 12.67 mm on the right and 6.01 to 12.74 mm on the left side. The
mean height of pedicle varied from 11.01 to 9.16 mm on the right and 10.85 to 9.28
mm on the left side [Table 5].
Table 5
Descriptive analysis of pedicle diameter and height in study population (N = 44)
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
5.89 ± 0.83
|
5.64
|
6.14
|
11.01 ± 1.31
|
10.61
|
11.41
|
|
L2 right
|
5.89 ± 0.74
|
5.66
|
6.11
|
10.18 ± 1.35
|
9.77
|
10.59
|
|
L3 right
|
7.21 ± 0.91
|
6.93
|
7.49
|
10.21 ± 0.93
|
9.93
|
10.49
|
|
L4 right
|
8.93 ± 1.68
|
8.41
|
9.44
|
9.86 ± 1.56
|
9.39
|
10.34
|
|
L5 right
|
12.67 ± 2.12
|
12.02
|
13.31
|
9.16 ± 0.87
|
8.89
|
9.42
|
|
L1 left
|
6.01 ± 0.82
|
5.76
|
6.26
|
10.85 ± 1.12
|
10.51
|
11.19
|
|
L2 left
|
6.14 ± 0.73
|
5.92
|
6.36
|
10.06 ± 1.26
|
9.67
|
10.44
|
|
L3 left
|
7.13 ± 0.96
|
6.84
|
7.42
|
10.2 ± 0.97
|
9.90
|
10.49
|
|
L4 left
|
8.93 ± 1.49
|
8.48
|
9.39
|
9.74 ± 1.46
|
9.30
|
10.19
|
|
L5 left
|
12.74 ± 2.04
|
12.12
|
13.36
|
9.28 ± 0.89
|
9.01
|
9.55
|
In the age group of 31 to 40 years (n = 44), the mean transverse angulation of the
pedicle varied from 22.97 to 35.89 degrees on the right and 22.92 to 35.78 degrees
on the left side. The mean lateral angulation of pedicle varied from 22.24 to 21.9
degrees on the right and 22.06 to 21.23 degrees on the left side [Table 6].
Table 6
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal in study
population (N = 44)
|
Parameter
|
Axial mean ± SD (mm)
|
95% CI
|
Lateral mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
22.97 ± 1.21
|
22.60
|
23.34
|
22.24 ± 2.93
|
21.35
|
23.13
|
|
L2 right
|
23.45 ± 1.48
|
23.00
|
23.90
|
21.45 ± 1.67
|
20.95
|
21.96
|
|
L3 right
|
25.3 ± 1.53
|
24.83
|
25.76
|
21.36 ± 2.13
|
20.71
|
22.01
|
|
L4 right
|
28.61 ± 1.37
|
28.19
|
29.03
|
20 ± 2.25
|
19.32
|
20.68
|
|
L5 right
|
35.89 ± 2.89
|
35.01
|
36.77
|
21.9 ± 2.78
|
21.05
|
22.74
|
|
L1 left
|
22.92 ± 1.2
|
22.56
|
23.29
|
22.06 ± 2.56
|
21.28
|
22.83
|
|
L2 left
|
23.18 ± 1.5
|
22.72
|
23.63
|
21.56 ± 1.76
|
21.02
|
22.09
|
|
L3 left
|
25.46 ± 1.71
|
24.94
|
25.98
|
21.16 ± 2.13
|
20.51
|
21.81
|
|
L4 left
|
28.68 ± 1.33
|
28.27
|
29.08
|
20.1 ± 2.29
|
19.40
|
20.79
|
|
L5 left
|
35.78 ± 3.05
|
34.85
|
36.71
|
21.23 ± 2.58
|
20.44
|
22.01
|
In the Age Group of 41 to 50 Years
In the Age Group of 41 to 50 Years
In the age group of 41 to 50 years (n = 51), the mean axial diameter of the pedicle
varied from 5.4 to 11.89 mm on the right and 5.29 to 11.49 mm on the left side. The
mean height of pedicle varied from 10.8 to 8.57 mm on the right and 10.98 to 8.51
mm on the left side [Table 7].
Table 7
Descriptive analysis of pedicle diameter and height in study population (N = 51)
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
5.4 ± 0.93
|
5.14
|
5.66
|
10.8 ± 0.9
|
10.55
|
11.05
|
|
L2 right
|
5.71 ± 0.84
|
5.47
|
5.94
|
10.2 ± 0.8
|
9.97
|
10.42
|
|
L3 right
|
6.89 ± 1.08
|
6.59
|
7.20
|
10.47 ± 1.04
|
10.18
|
10.77
|
|
L4 right
|
8.67 ± 1.08
|
8.37
|
8.98
|
9.55 ± 1.16
|
9.22
|
9.87
|
|
L5 right
|
11.58 ± 1.48
|
11.16
|
12.00
|
8.57 ± 0.85
|
8.33
|
8.81
|
|
L1 left
|
5.29 ± 0.97
|
5.02
|
5.57
|
10.91 ± 0.92
|
10.65
|
11.17
|
|
L2 left
|
5.74 ± 0.85
|
5.50
|
5.98
|
10.17 ± 0.79
|
9.94
|
10.39
|
|
L3 left
|
6.76 ± 1.1
|
6.45
|
7.07
|
10.2 ± 1.01
|
9.92
|
10.49
|
|
L4 left
|
8.31 ± 1.22
|
7.96
|
8.65
|
9.24 ± 1.04
|
8.95
|
9.54
|
|
L5 left
|
11.49 ± 1.46
|
11.08
|
11.90
|
8.58 ± 0.88
|
8.33
|
8.83
|
In the age group of 41 to 50 years (n = 51), the mean transverse angulation of the
pedicle varied from 22.78 to 36.08 degrees on the right and 22.7 to 36.18 degrees
on the left side. The mean lateral angulation of pedicle varied from 22.71 to 22.47
degrees on the right and 21.48 to 21.38 degrees on the left side [Table 8].
Table 8
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal in study
population (N = 51)
|
Parameter
|
Axial mean ± SD (mm)
|
95% CI
|
Lateral mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
22.78 ± 2.36
|
22.11
|
23.44
|
21.71 ± 3.4
|
20.76
|
22.67
|
|
L2 right
|
23.46 ± 2.43
|
22.77
|
24.14
|
19.98 ± 2.9
|
19.17
|
20.80
|
|
L3 right
|
25.15 ± 1.97
|
24.59
|
25.70
|
20.86 ± 2.63
|
20.11
|
21.60
|
|
L4 right
|
28.38 ± 2.46
|
27.68
|
29.07
|
20.13 ± 2.37
|
19.47
|
20.80
|
|
L5 right
|
36.08 ± 5.05
|
34.66
|
37.50
|
22.47 ± 3.1
|
21.60
|
23.34
|
|
L1 left
|
22.7 ± 2.39
|
22.03
|
23.37
|
21.48 ± 3.15
|
20.59
|
22.36
|
|
L2 left
|
23.48 ± 2.41
|
22.81
|
24.16
|
20.1 ± 2.86
|
19.30
|
20.91
|
|
L3 left
|
25.11 ± 2.1
|
24.52
|
25.70
|
20.46 ± 2.24
|
19.83
|
21.09
|
|
L4 left
|
28.27 ± 2.57
|
27.54
|
28.99
|
19.31 ± 2.55
|
18.59
|
20.03
|
|
L5 left
|
36.13 ± 5.2
|
34.67
|
37.60
|
21.38 ± 3.46
|
20.41
|
22.36
|
In the Age Group of 51 to 60 Years
In the Age Group of 51 to 60 Years
In the age group of 51 to 60 years (n = 54), the mean axial diameter of the pedicle
varied from 5.88 to 11.92 mm on the right and 5.84 to 11.53 mm on the left side. The
mean height of pedicle varied from 11.01 to 9 mm on the right and 10.89 to 8.85 mm
on the left side [Table 9].
Table 9
Descriptive analysis of pedicle diameter and height in study population (N = 54)
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
5.88 ± 1.35
|
5.51
|
6.25
|
11.01 ± 1.78
|
10.52
|
11.49
|
|
L2 right
|
6.52 ± 1.66
|
6.07
|
6.98
|
10.46 ± 1.68
|
10.00
|
10.92
|
|
L3 right
|
7.89 ± 1.88
|
7.37
|
8.40
|
10.12 ± 1.59
|
9.69
|
10.56
|
|
L4 right
|
9.1 ± 1.94
|
8.57
|
9.63
|
9.53 ± 1.56
|
9.10
|
9.95
|
|
L5 right
|
11.92 ± 2.74
|
11.18
|
12.67
|
9 ± 1.77
|
8.52
|
9.48
|
|
L1 left
|
5.84 ± 1.33
|
5.47
|
6.20
|
10.89 ± 1.64
|
10.45
|
11.34
|
|
L2 left
|
6.5 ± 1.75
|
6.02
|
6.97
|
10.23 ± 1.48
|
9.83
|
10.64
|
|
L3 left
|
7.88 ± 1.87
|
7.37
|
8.39
|
9.85 ± 1.3
|
9.49
|
10.20
|
|
L4 left
|
8.97 ± 2.13
|
8.39
|
9.55
|
9.33 ± 1.19
|
9.01
|
9.66
|
|
L5 left
|
11.53 ± 2.07
|
10.97
|
12.10
|
8.85 ± 1.7
|
8.38
|
9.31
|
In the age group of 51 to 60 years (n = 54), the mean transverse angulation of the
pedicle varied from 23.2 to 32.88 degrees on the right and 23.21 to 32.39 degrees
on the left side. The mean sagittal angulation of pedicle varied from 18.27 to 19.1
degrees on the right and 18.34 to 20.09 degrees on the left side [Table 10].
Table 10
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal in study
population (N = 54)
|
Parameter
|
Axial mean ± SD
|
95% CI
|
Lateral mean ± SD
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
23.2 ± 1.97
|
22.66
|
23.73
|
18.27 ± 2.66
|
17.54
|
18.99
|
|
L2 right
|
23.03 ± 1.71
|
22.57
|
23.50
|
17.99 ± 2.96
|
17.18
|
18.80
|
|
L3 right
|
25.13 ± 2.19
|
24.54
|
25.73
|
17.75 ± 2.91
|
16.96
|
18.55
|
|
L4 right
|
27.83 ± 2.55
|
27.14
|
28.53
|
18.17 ± 3.07
|
17.33
|
19.01
|
|
L5 right
|
32.88 ± 4.74
|
31.59
|
34.17
|
19.1 ± 5.25
|
17.67
|
20.53
|
|
L1 left
|
23.21 ± 1.91
|
22.69
|
23.73
|
18.34 ± 2.72
|
17.59
|
19.08
|
|
L2 left
|
23.39 ± 1.56
|
22.97
|
23.82
|
18.22 ± 2.93
|
17.41
|
19.02
|
|
L3 left
|
25.16 ± 2.1
|
24.59
|
25.73
|
17.73 ± 2.73
|
16.98
|
18.48
|
|
L4 left
|
27.64 ± 2.65
|
26.92
|
28.36
|
18.44 ± 3.04
|
17.60
|
19.27
|
|
L5 left
|
32.98 ± 4.72
|
31.69
|
34.27
|
20.09 ± 4.7
|
18.80
|
21.39
|
In the Age Group of 61 to 70 Years
In the Age Group of 61 to 70 Years
In the age group of 61 to 70 years (n = 45), the mean axial diameter of the pedicle
varied from 5.87 to 11.09 mm on the right and 5.95 to 10.79 mm on the left side. The
mean height of pedicle varied from 10.59 to 8.7 mm on the right and 10.46 to 8.52
mm on the left side [Table 11].
Table 11
Descriptive analysis of pedicle diameter and height in study population (N = 45)
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
5.87 ± 0.79
|
5.64
|
6.11
|
10.59 ± 1.72
|
10.07
|
11.10
|
|
L2 right
|
6.24 ± 1.03
|
5.93
|
6.54
|
10.21 ± 1.64
|
9.72
|
10.70
|
|
L3 right
|
7.47 ± 1.73
|
6.95
|
7.99
|
9.99 ± 1.54
|
9.52
|
10.45
|
|
L4 right
|
8.88 ± 1.74
|
8.36
|
9.40
|
9.36 ± 1.21
|
9.00
|
9.72
|
|
L5 right
|
11.09 ± 1.58
|
10.62
|
11.57
|
8.77 ± 1.06
|
8.45
|
9.09
|
|
L1 left
|
5.95 ± 0.76
|
5.72
|
6.18
|
10.46 ± 1.56
|
10.00
|
10.93
|
|
L2 left
|
6.19 ± 1.03
|
5.88
|
6.50
|
9.93 ± 1.36
|
9.52
|
10.34
|
|
L3 left
|
7.42 ± 1.58
|
6.95
|
7.90
|
9.68 ± 1.48
|
9.24
|
10.13
|
|
L4 left
|
8.75 ± 1.92
|
8.17
|
9.33
|
9.4 ± 1.04
|
9.09
|
9.71
|
|
L5 left
|
10.79 ± 1.54
|
10.33
|
11.25
|
8.52 ± 1
|
8.21
|
8.82
|
In the age group of 61 to 70 years (n = 45), the mean transverse angulation of the
pedicle varied from 23.73 to 31.94 degrees on the right and 23.87 to 32.32 degrees
on the left side. The mean sagittal angulation of pedicle varied from 17.95 to 17.4
degrees on the right and 17.95 to 17.57 degrees on the left side [Table 12].
Table 12
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal in study
population (N = 45)
|
Parameter
|
Axial mean ± SD (mm)
|
95% CI
|
Lateral mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
23.73 ± 1.71
|
23.21
|
24.24
|
17.95 ± 3.3
|
16.96
|
18.94
|
|
L2 right
|
23.05 ± 1.65
|
22.55
|
23.55
|
17.52 ± 3.24
|
16.54
|
18.49
|
|
L3 right
|
24.8 ± 1.67
|
24.30
|
25.31
|
16.75 ± 1.99
|
16.15
|
17.34
|
|
L4 right
|
27.81 ± 2.18
|
27.16
|
28.47
|
16.6 ± 2.62
|
15.81
|
17.39
|
|
L5 right
|
31.94 ± 4.99
|
30.44
|
33.44
|
17.4 ± 4.91
|
15.93
|
18.88
|
|
L1 left
|
23.87 ± 1.54
|
23.41
|
24.34
|
17.95 ± 3.1
|
17.02
|
18.88
|
|
L2 left
|
23.44 ± 1.52
|
22.98
|
23.90
|
17.57 ± 3.22
|
16.60
|
18.53
|
|
L3 left
|
24.89 ± 1.59
|
24.41
|
25.37
|
16.88 ± 1.97
|
16.28
|
17.47
|
|
L4 left
|
27.43 ± 2.58
|
26.65
|
28.20
|
16.68 ± 2.83
|
15.83
|
17.53
|
|
L5 left
|
32.32 ± 5.03
|
30.80
|
33.83
|
17.57 ± 4.9
|
16.10
|
19.04
|
In the Age Group of 71 to 80 Years
In the Age Group of 71 to 80 Years
In the age group of 71 to 80 years (n = 30), the mean axial diameter of the pedicle
varied from 4.9 to 10.37 mm on the right and 4.7 to 10.49 mm on the left side. The
mean height of pedicle varied from 10.03 to 7.7 mm on the right and 10.1 to 7.73 mm
on the left side [Table 13].
Table 13
Descriptive analysis of pedicle diameter and height in study population (N = 30).
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
4.9 ± 0.98
|
4.54
|
5.27
|
10.03 ± 1.39
|
9.52
|
10.55
|
|
L2 right
|
5.64 ± 1.01
|
5.26
|
6.02
|
10.2 ± 1.4
|
9.68
|
10.73
|
|
L3 right
|
6.05 ± 1.63
|
5.44
|
6.65
|
9.77 ± 1.24
|
9.30
|
10.23
|
|
L4 right
|
7.03 ± 1.75
|
6.37
|
7.68
|
8.27 ± 1.45
|
7.72
|
8.81
|
|
L5 right
|
10.37 ± 2.12
|
9.58
|
11.16
|
7.77 ± 1.7
|
7.13
|
8.40
|
|
L1 left
|
4.7 ± 1.09
|
4.29
|
5.10
|
10.1 ± 1.45
|
9.56
|
10.64
|
|
L2 left
|
5.65 ± 1.02
|
5.27
|
6.03
|
10 ± 1.41
|
9.47
|
10.53
|
|
L3 left
|
6.52 ± 1.46
|
5.97
|
7.06
|
9.81 ± 1.09
|
9.40
|
10.22
|
|
L4 left
|
7.13 ± 1.91
|
6.42
|
7.84
|
8.23 ± 1.34
|
7.73
|
8.73
|
|
L5 left
|
10.49 ± 2.24
|
9.65
|
11.33
|
7.73 ± 1.59
|
7.13
|
8.32
|
In the age group of 71 to 80 years (n = 30), the mean transverse angulation of the
pedicle varied from 22.6 to 31.99 degrees on the right and 22.07 to 32.45 degrees
on the left side. The mean sagittal angulation of pedicle varied from 18.44 to 15.56
degrees on the right and 18.77 to 15.83 degrees on the left side [Table 14].
Table 14
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal in study
population (N = 30).
|
Parameter
|
Axial mean ± SD (mm)
|
95% CI
|
Lateral mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
22.6 ± 1.53
|
22.02
|
23.17
|
18.44 ± 1.44
|
17.90
|
18.98
|
|
L2 right
|
22.02 ± 0.92
|
21.68
|
22.36
|
16.54 ± 1.52
|
15.97
|
17.11
|
|
L3 right
|
23.84 ± 1.72
|
23.20
|
24.48
|
16.04 ± 1.29
|
15.56
|
16.52
|
|
L4 right
|
28.48 ± 1.35
|
27.98
|
28.99
|
17.36 ± 1.82
|
16.68
|
18.04
|
|
L5 right
|
31.99 ± 2.33
|
31.12
|
32.86
|
15.56 ± 3.14
|
14.39
|
16.74
|
|
L1 left
|
22.07 ± 1.56
|
21.49
|
22.65
|
18.77 ± 1.47
|
18.22
|
19.32
|
|
L2 left
|
22.05 ± 1.35
|
21.54
|
22.55
|
17.03 ± 1.46
|
16.48
|
17.57
|
|
L3 left
|
23.45 ± 1.83
|
22.77
|
24.14
|
16.46 ± 1.38
|
15.94
|
16.98
|
|
L4 left
|
28.72 ± 1.47
|
28.17
|
29.26
|
17.43 ± 1.81
|
16.76
|
18.11
|
|
L5 left
|
32.45 ± 2.4
|
31.55
|
33.35
|
15.83 ± 2.79
|
14.79
|
16.87
|
In the Age Group of 81 to 90 Years
In the Age Group of 81 to 90 Years
In the age group of 81 to 90 years (n = 14), the mean axial diameter of the pedicle
varied from 4.66 to 10.21 mm on the right and 4.46 to 10.29 mm on the left side. The
mean height of pedicle varied from 9.78 to 7.49 mm on the right and 9.49 to 7.38 mm
on the left side [Table 15].
Table 15
Descriptive analysis of pedicle diameter and height in study population (N = 14)
|
Parameter
|
Diameter mean ± SD (mm)
|
95% CI
|
Height mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
4.66 ± 0.89
|
4.14
|
5.17
|
9.78 ± 1.25
|
9.06
|
10.50
|
|
L2 right
|
5.71 ± 1.35
|
4.93
|
6.50
|
10.15 ± 1.16
|
9.48
|
10.82
|
|
L3 right
|
5.79 ± 1.64
|
4.84
|
6.73
|
9.44 ± 0.45
|
9.19
|
9.70
|
|
L4 right
|
6.84 ± 1.83
|
5.78
|
7.89
|
7.95 ± 0.73
|
7.53
|
8.37
|
|
L5 right
|
10.21 ± 1.93
|
9.09
|
11.32
|
7.49 ± 1.63
|
6.55
|
8.43
|
|
L1 left
|
4.46 ± 0.95
|
3.91
|
5.02
|
9.49 ± 1.2
|
8.80
|
10.19
|
|
L2 left
|
5.62 ± 1.28
|
4.88
|
6.36
|
9.89 ± 1.06
|
9.28
|
10.51
|
|
L3 left
|
5.89 ± 1.66
|
4.93
|
6.85
|
9.44 ± 0.38
|
9.22
|
9.66
|
|
L4 left
|
6.91 ± 1.89
|
5.81
|
8.00
|
7.56 ± 0.91
|
7.03
|
8.08
|
|
L5 left
|
10.29 ± 2.23
|
9.00
|
11.58
|
7.38 ± 1.57
|
6.47
|
8.29
|
In the age group of 81 to 60 years (n = 14), the mean transverse angulation of the
pedicle varied from 22.94 to 32.27 degrees on the right and 22.64 to 32.57 degrees
on the left side. The mean sagittal angulation of pedicle varied from 18.44 to 16.12
degrees on the right and 18.69 to 16.4 degrees on the left side [Table 16].
Table 16
Descriptive analysis of pedicle body angulation transverse (TA) and sagittal in study
population (N = 14).
|
Parameter
|
Axial mean ± SD (mm)
|
95% CI
|
Lateral mean ± SD (mm)
|
95% CI
|
|
Lower
|
Upper
|
Lower
|
Upper
|
|
L1 right
|
22.94 ± 0.85
|
22.45
|
23.43
|
18.44 ± 0.88
|
17.93
|
18.95
|
|
L2 right
|
22.41 ± 1.67
|
21.45
|
23.38
|
16.81 ± 1.89
|
15.71
|
17.90
|
|
L3 right
|
24.14 ± 2
|
22.98
|
25.29
|
16.13 ± 1.52
|
15.25
|
17.01
|
|
L4 right
|
29.13 ± 1.19
|
28.44
|
29.82
|
17.4 ± 0.98
|
16.84
|
17.96
|
|
L5 right
|
32.27 ± 1.8
|
31.23
|
33.31
|
16.12 ± 3.21
|
14.27
|
17.98
|
|
L1 left
|
22.64 ± 1.06
|
22.03
|
23.25
|
18.69 ± 0.81
|
18.22
|
19.15
|
|
L2 left
|
22.27 ± 1.6
|
21.35
|
23.20
|
17.42 ± 1.73
|
16.42
|
18.42
|
|
L3 left
|
23.91 ± 2.11
|
22.69
|
25.13
|
16.4 ± 1.38
|
15.60
|
17.20
|
|
L4 left
|
29.38 ± 0.84
|
28.89
|
29.86
|
17.64 ± 1.04
|
17.05
|
18.24
|
|
L5 left
|
32.57 ± 1.77
|
31.55
|
33.59
|
16.4 ± 2.8
|
14.78
|
18.02
|
Discussion
Low-back pain is the second most common complaint encountered by primary care physicians.
After the invention of CT scan in 1991, there was a sudden revolutionary change in
the medical management of low backache. It changed the perspective of the surgeons
in terms of spinal surgeries and augmented the method of study of the lumbar spine
anatomy noninvasively, making the decisions in terms of spinal instrumentation. For
safe pedicle screws placement, knowledge of pedicle morphometry is compulsory because
inconsistency between pedicle width and the screw diameter may lead to severe complications
like nerve, vessel or visceral injuries.
Multidetector CT is the modality of choice for evaluation of detailed morphometry
of spinal pedicles. The available lumbar morphometric normograms are of few parameters
which are based on radiographs or cadaver and cannot be directly applied to plan surgical
treatment. There has been reported data available from European countries using cadaveric
measurements, but these measurements do not necessarily apply to the spine in the
normal Indian population.[9] Very few studies of CT morphometry are available in the Indian literature. Normal
values for various pedicle dimensions by CT scan are lacking among the Indian population.
Pedicle morphometric parameters show significant variations in different studies,
which can be due to different characteristics of different populations studied.
Our study reveals pedicle dimension at all lumbar levels varying with age and heterogeneous
ethnicity. It also shows that pedicles width in axial plane varies from 4.46 to 11.32
mm at L1–L5 levels in different age groups. The pedicles heights in the sagittal plane
in our sample vary from 7.38 to 12.01 mm among the 10 to 90 years age group. Pedicles
angulation in axial plane varies from 22.27 to 36.08 degree and lateral pedicle angulation
in sagittal plane varies from 16.12 to 22.47 degree at L1–L5 levels among the 10 to
90 years age groups, respectively.
In the present study, the mean pedicle dimensions were greater than those mentioned
by Signel et al and Arora et al at all lumbar levels. This difference between our
study and that described by Signel et al and Arora et al study was due to large sample
size, population of different age group, and inclusion of population of different
ethnicity or racial difference. In our study, there was no statistically significant
difference in the measured values in right and left side in both genders.[10]
[11]
[12]
Kang et al comparing pedicle diameter between the plain radiographs and CT scans in
the lower thoracic and lumbar spinal levels (from T9 to L5) found that underestimation
of the pedicle diameter in plain radiographs because of the fact that the maximum
radiologic density of the pedicle is well within the true cortical margin of the pedicle
due to complex transverse and sagittal pedicle angles at each spinal level.[14]
[15]
In a study by Chadha et al, the subset of patients was from the Indian subcontinent,
where they have calculated morphometry values from T9 till S1. Our study differs from
this study in the sense that all our parameters were evaluated on work station and
not on films which may not be the correct methods of measurement. Furthermore, to
calculate the sagittal angulation oblique, images were created at the workstation.
Our study tries to bring out the data for spinal pedicle morphometry at L1 to L5 levels
and at different age groups.[16]
In a study by Acharya et al, the authors included lower thoracic and all lumbar vertebrae.
In their study, a total of 50 patients were included. In our study, a total of 321
participants were included and hence the accuracy of data, as per age stratification,
is likely to be more accurate.[17]
Transpedicular spinal fixation has gained importance these days throughout the world
but there is requirement of precise knowledge of morphology of pedicles and its relation
with neural structures for safe and efficient surgery. The strength of the stabilized
segment will depend upon the soundness of the screw fixation within the pedicles and
the design of the fixation system.
Lee et al showed 98% accuracy in transpedicular screw fixation using the intraoperative
CT navigation system in stabilizing unstable thoracolumbar spine fractures. A misplaced
transpedicular screw could be revised immediately during real-time confirmation of
the transpedicular screw position, hence preventing second revision surgery. The intraoperative
CT navigation system provided an accurate and safe alternative for management of unstable
thoracolumbar spine fractures.[18]
Presently, CT is the modality of choice for computing various measurements for transpedicular
fixation. Hence, based on all observations, preoperative CT imaging with as thinner
slices as possible is recommended for more accurate assessment of the morphometric
characteristics of the lumbar pedicle and the placement of the screws.
Conclusions
-
Multidetector CT imaging is the noninvasive modality of choice for evaluation of detailed
morphometry of spinal pedicles and helps in making the decisions in terms of spinal
instrumentation.
-
Our study is the first of its kind based on a large population with different age
groups (18–90 years), as per the review of literature, to provide details of lumbar
spinal pedicle morphometry from the Indian subcontinent.
Table 17
Comparison of various lumbar spine pedicle parameters (mm) (literature comparison
with present study)
|
Vertebra
|
Amonoo-Kuofi[11]
|
Singel et al[9]
|
Arora et al[10]
|
Present study
|
|
Male
|
Female
|
Male
|
Female
|
Male
|
Female right
|
Left
|
|
|
L1 width
|
10.3
|
8.7
|
8.2
|
8.5
|
7.51
|
7.49
|
5.88
|
5.84
|
|
L1 height
|
19.4
|
16.3
|
14.7
|
15.5
|
14.79
|
14.34
|
11.01
|
10.89
|
|
L2 width
|
10.7
|
9
|
8.5
|
8.75
|
7.95
|
7.91
|
6.52
|
6.50
|
|
L2 height
|
18.9
|
15.3
|
15
|
14.5
|
15.42
|
15.04
|
10.46
|
10.23
|
|
L3 width
|
12.1
|
10.5
|
10.4
|
10.6
|
8.75
|
8.7
|
17.89
|
7.88
|
|
L3 height
|
19.3
|
15.9
|
14.7
|
14.8
|
16.42
|
15.6
|
10.12
|
9.85
|
|
L4 width
|
13
|
11.1
|
13.5
|
13.8
|
13
|
12.97
|
9.10
|
8.97
|
|
L4 height
|
19.9
|
16.1
|
14
|
14
|
17.48
|
17.11
|
9.53
|
9.33
|
|
L5 width
|
–
|
–
|
–
|
–
|
–
|
–
|
11.92
|
11.53
|
|
L5 height
|
–
|
–
|
–
|
–
|
–
|
–
|
9.00
|
8.85
|
