Bull Vet Inst Pulawy 52, 285-289, 2008
SPONGIOUS MATRIX OF THE TIBIO-TARSAL BONE
OF OSTRICHES (STRUTHIO CAMELUS)
– A DIGITAL ANALYSIS
ANNA CHARUTA, TOMASZ MAJCHRZAK1,
EDWARD CZERWIŃSKI2, AND ROSS G. COOPER3
Vertebrates Morphology Department, Faculty of Agriculture, University of Podlasie, 08-110 Siedlce, Poland
1
Department of Mechanics and Vibroacoustics, Faculty of Mechanical Engineering and Robotics,
AGH University of Science and Technology, 30-059 Kraków, Poland
2
Institute of Bone and Joint Diseases, Faculty of the Physiotherapy,
Jagiellonian University Medical College in Kraków, 31-501 Kraków, Poland
3
Department of Physiology, UCE Birmingham, Perry Barr, Birmingham B42 2SU, UK
[email protected]
Received for publication February 14, 2008
Abstract
A novel diagnostic method was adapted from studies
in horses and humans to postmortal research on ostrich bones.
The research made it possible to determine referential values in
the method of digital analysis of a radiological image for the
tibio-tarsal bone of the ostrich, following exposure to injuries.
In the case of a computer-generated analysis of a radiological
image, the optimal conditions for taking images were selected,
along with their digital record and processing: 0.096 mm/pixel,
256 greyness level (8 bits), and scanning in BMP (a bitmap
that is an open format of raster graphics, a block of bytes,
which describes an image pixel by pixel). The research was
conducted on the rectangular-shaped (160 x 320 points)
spongy bone taken about 80 mm below the articular surface
near the proximal metaphysis. The research allowed defining
parameters of the spongious matrix of the tibio-tarsal bone of
healthy 14-month-old ostriches. The average number of
trabeculae on lines was 10.41 mm2 for both sexes, the average
volume was 2.21 %, the density of the trabeculation (the
percentage of the surface covered with trabeculae) was 47.44
% for both sexes and the average width of the trabeculae was
0.23 mm. On the basis of the conducted calculations, it is
possible to draw a conclusion that the average number of
radiological trabeculae, the volume of the trabeculae, and their
density do not differ significantly for cocks and hens.
Key words: ostrich, tibio-tarsus, radiography,
Trabecula®.
The African ostrich (Struthio camelus australis)
is a popular livestock animal principally due to its
nutritive and dietetic meat and highly valued skin (5, 6,
18, 19, 23). Therefore, ostrich farming has a global
perspective (15, 16). One of the problems facing the
industry are disturbances in skeletal development up to 6
months of age. During this period, various skeletal
problems including leg deformities of the tibio-tarsal
and tarsal-metatarsal bones may be caused by factors
that include improper feeding and unsuitably balanced
diets (6, 7, 8). Younger birds have a bigger proportion of
muscle tissue than skeletal mass leading to excessive
load and fractures of the bones of the pelvis limb (20).
Apart from that, intensive egg production may recruit an
increased demand of calcium mobilised from bones to
form eggshells and limited locomotor activities may also
predispose hens to osteoporosis (27, 29). Considering
the widely reported existence of skeletal aberrations in
ostriches (1, 2, 17), there is a need to carry out a detailed
radiographic analysis of the healthy structure of ostrich
bone tissue.
Currently, there are many methods of intravital
evaluation of the poultry skeletal system, such as
radiography (22), absorptiometry of X-radiation with
double energy (24), digital fluoroscopy (13),
quantitative computer tomography (26, 28), and
quantitative ultrasonography (13). These methods can be
utilised to select animals with optimally developed and
mineralised skeletal systems for breeding programmes.
One of the new methods using digital analysis
of images is Trabecula®. It is a programme describing
many parameters of the bone tissue, such as total
number of trabeculae per mm2, volume, density, and
width and height of trabeculae (9). Trabeculae allow
intravital evaluation of the bone tissue. Using this
programme, probability of fracture can be predicted and
it is possible to take some preventive measures (10, 11).
The method is widely used in diagnostics of fluorine and
osteoporotic changes in humans (3, 14, 21) and in
veterinary medicine to study the structure of horses’
pastern bones (12).
The aim of the current research was to adapt a
new non-invasive method of bone structural analysis in
286
humans to a structural study of the tibio-tarsal bone of
the ostrich; to determine optimal parameters of analysis
using radiological images of ostriches, to show sexual
differences between them, and, finally, to define the
values of some parameters of the spongious matrix of
the tibio-tarsal bone in selected birds.
Material and Methods
The research material consisted of 20
radiographs collected from tibio-tarsal bones of
ostriches (10 males and 10 females) approximately 14month-old. To establish the differences of the studied
quantitative traits associated with sex, the obtained
results were analysed separately for cocks and hens.
The size of the cassettes and radiograms was
15x40 cm. The image on the radiograms was in natural
size. They came from a farm in Stanisławów, located
near Warsaw (52o 17’ N, 21o 32’ E). The ambient
temperature was –8ºC and relative humidity 90%.
Before slaughtering, the birds were weighed precisely
using a TP-1500/4 RPT97262 scale (Lubelskie Fabryki
Wag "FAWAG", Lublin, Poland) and their sex was
determined after laparotomy. Radiographs were made
with an X-ray apparatus EDR 750B, using 50 kVp rays
and radiation rate of 20 mAs, considering a distance of
120 cm between the spot of X-ray tube and a Cawo
cassette (Cawo SE4 blue 400). The X-ray machine
consisted of generator (50 kV, 120kV) and table for
radiography equipped with Bucky grid. Only the small
spot of the X-ray tube was used for the radiography. The
dissected bones were put directly on a cassette without a
Bucky grid usage during radiography. The black and
white Kodak (M35-MX-OMAT) films were then
processed automatically in the Radiodiagnostic unit of a
local hospital (Siedlce).
Only high quality pictures were analysed and
used in the study. The fragment where the whole bone
was seen was scanned. The radiograms were digitalised
using an apparatus with a charge-coupled device CCD:
2560 x1920 pixels. The bitmaps received were recorded
at a resolution of 0.096 mm/pixel and at a 256 greyness
level. The record was made in BMP (a bitmap).
The Trabecula® programme works on the basis
of a compatible algorithm of radiological recognising of
trabeculae according to the formulated definition
focusing on such parameters as the angle and the level
of a microdensitometer curve. A segment of a
densitometer curve in a quadrilateral shape with a rising
stage, a plateau, and a falling arm is seen as a
radiological image of trabecula. A map of trabeculae is
generated and these are described according to quantity,
volume, and density.
The fragments chosen for the analysis of the
structure of the spongious substance of the tibio-tarsal
bone were rectangular-shaped (160 x 320 points),
dissected approximately 80 mm below the articular
surface near the proximal metaphysis (Fig. 1). To
establish which of the parameters were optimal while
analysing, the structure of the tibio-tarsal bones and
number of trabeculae in given horizontal lines on the
marked surface of the radiogram were determined with a
naked eye. Thereafter, the number thereof was compared
with the results achieved using the Trabecula®
programme, which depended on the selection of
individual parameters (vertical angle - 20o degrees, level
– 40%, and width – 200%). The level was measured in
percentages because we analysed radiograms - the
greyness scale digitally (from the darkest point to the
lightest one - the percentage was the threshold value
<gradient> of the difference between the minimum and
maximum of the optical density of the analysed image).
As the resolution of a human eye is similar to the
resolution of the Trabecula® programme, the results
were comparable (10.41 mm2).
According to this algorithm, the programme
automatically analysed the trabeculae surface,
densitometer curves and generated a map of recognised
trabeculae, thereafter calculating their characteristics for
the whole surface as an average from the analysis of the
given 320 horizontal lines on the horizontal image.
Because a rectangle with basis of 160 points and the
height of 320 points were analysed, the scan contained
320 lines and each line had length of 160 points. As the
result, we achieved a list of trabeculae for each line of
the horizontal cross-section of the image, on the basis of
which a map of trabeculae was created. The programme
generated the trabecula map and for the entire area of
the analysis it calculated: the number of radiologically
recognised trabeculae per mm2 of the marked analysis
area; the average volume of the trabeculae as a
percentage of the volume of a cube with the maximal
and minimal basis measured and given in % mm and
density given as a percentage of the surface covered
with trabeculae as well as the width of the trabecula
(Fig. 2).
In order to achieve the objective values of bone
measurements, an arithmetic average was calculated
( x ) marking the minimum and maximum parameters of
the studied bones (number, volume, density, width) as
well as the standard deviation (SD). The results were
analysed statistically by t-Student test using Windows
XP (95% CI) with α =0.05. The temp value was compared
with the tabular value. The averages differed
significantly when:
│temp│>t α,υ; t 0.05, 18,
where: α= 0.05; ν= (n1+n2)-2; and n1, n2 = number of
attempts.
The averages, which differed significantly, were marked
with different letters.
Birds used for the study were routinely
slaughtered and the bones were gained after
slaughtering. Therefore, the approval of Bioethical
Commission was not needed. The research was granted
by the University of Podlasie, Siedlce, Poland (Research
project 1036/07/w). The University received the funds
from the State Committee for Scientific Research
(KBN), Warsaw, Poland.
287
Fig. 1. A scanned fragment of a radiogram of the tibio-tarsal bone of the 14-month-old ostrich
with the marked area of analysis indicated.
Fig. 2. Computer analysis of a radiological image
of the spongious substance structure of the tibio- tarsal bone of one of the ostriches.
The image contains:
-on the left: at the top parameters of the radiographic trabeculae calculated by the programme for the whole marked
area, at the bottom a 3-dimensional image of the bone structure in the form of a graph with microdensitometrical curves.
- on the right: at the top a map of trabeculae discovered in the marked area, below - a fragment of the original image
generated by the computer, at the bottom: the radiological image of the discovered trabeculae on one of the
microdensitometrical curves.
288
Results and Discussion
Determining the parametric values in healthy
ostriches allowed us to compare the above parameters
with those existing in individuals experiencing skeletal
structural disorders or abnormalities. The research was
first conducted among humans (9, 10) and horses (11,
12). The current research showed that the adaptation of
the Trabecula® is a useful tool for studying the structure
of the spongious substance of the tibio-tarsal bone of
ostriches.
A resolution of 0.096 mm/pixel in the form of a
matrix with a 256 greyness level (8 bits) recorded in
Bitmap was recognised as optimal. The most credible
image of trabecula maps in the Trabecula® programme
in relation to the original radiogram for the tibio-tarsal
bone of ostriches was achieved for the following
parameters: an angle of 20o degrees, a level of 40%. The
results of the radiographic analysis using the
Trabecula® programme are shown in Table 1.
The average number of trabeculae analysed
radiologically was 10.42 per mm2 for cocks and 10.40
mm2 for hens. Their volume was 2.29% for cocks and
2.14% for hens, and their density was 47.72% for cocks
and 47.93% for hens. Using these selected parameters,
the average number of trabeculae for 128 measurement
lines were 10.41 for both sexes, the average volume –
2.21%, the average density (percentage of the area
covered with trabeculae) – 47.44 % for both sexes, and
the average width of trabeculae - 0.23 mm.
The results achieved are similar for both sexes
and did not show any statistical differences. The t value
for the average number of radiological trabeculae, their
volume, density, and width were 0.0726; 0.69; 0.766;
and 1.41, respectively.
The results achieved for the skeletal structure
on an example radiogram, depending on various
parameters, are shown in Table 1. The parameters of
bone trabeculae were: angle – 20o degrees, level - 40%,
and width - 200%. On the basis of all the calculations, it
is possible to draw a conclusion that an average number
of radiological trabaculae, their volume and density does
not differ significantly amongst cocks and hens. As it is
the first study of that kind conducted on ostriches, there
are no references in the literature, which would support
or reject our findings. Recently, the research has been
conducted, which allowed us to get to know the
macroscopic structure of the pelvic limb bones of
ostriches as far as length and width of the bones are
concerned (4).
The present study made it possible to determine
referential values in the method of digital analysis of a
radiological image of the tibio-tarsal bone of ostriches
previously subjected to mechanical injuries. The results
achieved can be classified and charted into standard
parameters whilst establishing the structure of the
spongious substance of the bone when using digital
image analysis. The conducted research can be extended
to the analysis and observations of other bones in
ostriches, for example wings and neck.
Table 1
Results of the analysis of the tibio-tarsal bone structure on a radiographic map
1
2
3
4
5
6
7
8
9
10
Min
Max
x
temp
SD
Cocks
n=10
Hens
n=10
Number of
trabeculae
per mm2
Volume of
trabeculae
(%)
Density of
trabeculae
(%)
Width of
trabeculae
(mm)
Number of
trabeculae
per mm2
Volume of
trabeculae
(%)
Density of
trabeculae
(%)
Width of
trabeculae
(mm)
10.43
11.09
11.37
10.18
10.99
10.10
10.80
9.32
9.35
10.58
9.32
11.37
10.42
0.0726
0.696
2.47
2.31
1.75
2.78
1.38
2.53
2.46
1.73
3.06
2.43
1.38
3.06
2.29
0.69
0.516
48.41
49.55
47.67
48.93
45.89
46.84
48.65
44.49
47.79
48.99
44.49
49.55
47.72
0.766
1.575
0.25
0.22
0.20
0.25
0.22
0.25
0.23
0.24
0.26
0.22
0.20
0.26
0.23
-1.41
0.018
10.45
10.85
9.37
10.34
10.40
10.40
10.40
11.15
10.49
10.12
9.37
11.15
10.40
0.0726
0.523
2.59
2.13
2.61
1.38
2.16
2.14
2.14
1.59
2.16
2.49
1.38
2.61
2.14
0.69
0.451
49.46
48.24
46.29
43.77
47.31
47.16
47.16
46.64
48.15
47.41
43.77
49.46
47.16
0.766
1.692
0.24
0.22
0.29
0.22
0.23
0.24
0.24
0.22
0.23
0.26
0.22
0.29
0.24
-1.41
0.024
Note: The averages (comparing cocks and hens) did not differ significantly, which implies that there is no sexual
dimorphism.
289
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