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Journal of the Anatomical Society of India

Identification Of Sex Of Sacrum Of Agra Region

Author(s): Mishra, S.R.; Singh, P.J.; Agrawal, A.K., Gupta, R.N.

Vol. 52, No. 2 (2003-07 - 2003-12)

Department of Anatomy, S.N. Medical College Society, Agra U.P. INDIA

Abstract

Various measurements of sacra of Agra region, available in the Department of Anatomy, S.N. Medical College Society, Agra, were taken and the various indices of sacrum were calculated. The demarking points of various parameters were calculated and the percentage of bones identified by D.P. was also recorded. The results were compared with the available literature. It was found that the demarking points of length of sacrum and length of auricular surface among the measurements and the sacral index and the auricular index among the indices were most reliable in sexing of sacra. Though, the Demarking Point (D.P.) of a single parameter may not identify sex in all the bones but the accuracy is 100% in the bones, which are identified.

Key words: Sacral index, Curvature index, Corporo-basal index, Alar index, Auricular index, Sacrum.

Introduction:

It has long been customary among anatomists, anthropologists and forensic experts to judge the sex of the skeletal material by non-metric observations. Lately, sexual divergence has been based upon actual measurements in different bones.

Though sacrum is often considered to be an important bone while dealing with sex differences in skeletal material, there is paucity of metrical data available for this bone. Metrical study of sacrum has been done by various authors (Wilder, 1920; Faweet, 1938; Davivongs, 1963.) Jit and Singh (1966) advocated the demarking point, which identify the sex with 100% accuracy. Singh and Gangrade (1968) have reported that even within the same general population, mean value may be significantly different in bones from different zones.

Singh and Singh (1972) have shown that demarking point should be calculated separately for different regions of population because the mean of a parameter differs in values in different regions.

The available literature clearly shows that the Indian sacra have not been studied widely except by Singh and Raju (1977) and Jana et al (1988). The materials studied by them are from Varanasi region and Burdwan regions respectively. Hence, the present study was undertaken with a view to study the sex-differences in the sacra of Agra region of Uttar Pradesh.

Material and Method:

The material for the present study consisted of 116 adult sacra (74 males and 42 females) of known sex available in the Department of Anatomy, S.N. Medical College, Agra. These sacra were selected after rejecting the bones, having any fractures, pathology or wear and tear. With the help of a stainless steel sliding caliper and flexible steel tape, the following measurements were taken (each linear measurement was recorded to the nearest millimeter ):

1. Maximum length of sacrum (Wilder's mid- ventral Straight length) -measured along the mid-line of sacrum with the sliding caliper from middle of antero-superior margin of promontory to middle of antero-inferior margin of the last sacral vertebra.

2. Maximum breadth of sacrum -measured with the sliding caliper by taking two points at the upper part of auricular surface anteriorly (or lateral most part of alae of sacrum), thus maximum breadth is measured on anterior aspect of sacrum.

3. Curved length of sacrum (Mid-ventral curved length)- measured along the mid line of the anterior surface of the sacrum (from middle of antero-superior margin of promontory to middle of antero-inferior margin of the last sacral vertebra) by the flexible steel tape.

4. Antero-posterior diameter of the body of Ist sacral vertebra - It is the maximum possible diameter of Ist sacral vertebra measured with the sliding caliper by taking one point on antero-superior border and another point on the postero-superior border of Ist sacral vertebral body.

5. Transverse diameter of the body of Ist sacral vertebra- It is the maximum transverse diameter of Ist sacral vertebra measured with the sliding caliper by taking one point on each side of the lateral most point on the superior surface of body of Ist sacral vertebra.

6. Length of alae -It is measured on both sides with the sliding caliper by taking one point on lateral most point of superior surface of body of Ist sacral vertebra and another point on lateral most part of alae. The mean of the length of the two sides is taken as length of alae.

7. Maximum length of auricular surface-It is the straight auricular length measured on lateral aspect of sacrum by means of a sliding caliper by taking one point on the upper most part of auricular surface and another point on the lower most part of auricular surface of sacrum.

By using the above measurements, the following indices were calculated:

1. Sacral index: (Width x 100) / Straight Length

2. Curvature index: (Straight Length x 100) / Mid -ventral curved length

3. Index of body of Ist Sacral vertebra: (AP daimeter of body of S 1 x 100) / Transeverse dia of body of S 1

4. Corporo-basal index: (Transverse diameter of body of S1 x 100) / Width of sacrum

5. Alar index: (Length of ala x 100) / Transverse diameter of body of S1

6. Auricular index: (Length of auricular surface x 100) / Width of sacrum

The demarking points (DP) of all the above parameters were calculated on the line of the work of Jit and Singh (1966) and percentage of bones identified by each parameter were worked out.

Observations:

The range, mean, calculated range (mean ± 3 S.D.) and demarking points (DP)of various parameters and the percentage of bones in which sex could be identified by them, are given in table-1

The mean values of all parameters except the width of sacrum and length of ala of sacrum were higher in males than the females. The mean value of sacral, alar index and the index of body of S1. are higher in females while the other three indices namely curvature index, corpobasal index and auricular index are higher in the males.

The differences in the mean values of males and females were analyzed statistically and their significance is shown in table-1. The width of sacrum and the anteroposterior diameter of body of S1 are the only two parameters, which showed insignificant difference between the males and females.

Table shows that the length of sacrum and sacral index are important parameters as far as the sex determination of sacrum is concerned because 71.6% of male bones and 80.1% of female bones could be identified by using the D.P. for the above parameters.

Discussion:

While teaching sex differences in bones much stress is laid on the importance of sacrum. Actually, very little data is available to test the validity of the number of parameters described to identify the sex of sacra (Davivongs, 1963). To be certain in identification, calculated range has to be considered, which is worked out by adding and subtracting 3 X standard deviations (SD) to and from the mean of any parameter. Jit and Singh (1966) have called the limiting point of such calculated range as demarking points, which identify sex with 100% accuracy (Rao, 1962) from any given region (Raju et al. 1981).

The demarking points of various parameters, if crossed by any sacrum will identify the sex with certainty, which is of paramount importance in medicolegal cases. However, it is not necessary for any bone to cross the D.Ps of all the parameters before sex could be identified. Any single D.P. for any of the parameters, if crossed would detect the sex with 100% accuracy (Singh and Raju, 1977)

The mean length of male sacra of Agra region (107.53mm) is higher than that of Varanasi region (104.96mm) studied by Raju et al. (1981). However, the female sacra of Agra region are shorter than the Varanasi region. Comas & Charles (1960) reported a wide variation between the male and female in the Chinese, Negroes and Bushmen. Devivongs (1963) in his study of Australian aboriginal sacra has reported mean length of sacrum to be 96.52mm and 88.12mm in the male and female respectively, which is much less than the Indian sacra studied so far. Thus there exists a regional and racial difference in the length of sacrum.

Table 1 : Showing various parameters of Sacrum and their statistical analysis.

Sr.No. Parameters Sex Range Mean S.D. 't' value 'p' value Calculated range
Mean ± 3 S.D.
D. P. % of bone identified by D. P.
1 Length of Sacrum (mm) M 92-122 107.53 7.03 14.153 <0.001 86.44-128.62 > 103.84 71.6
F 84-100 90.58 4.42 77.92-103.84 <86.44 23.08
2 Width of Sacrum (mm) M 92-120 105.34 6.22 0.372 >0.05 86.68-124.00 <86.83 0
F 92-118 105.79 6.32 86.83-124.75 >124.00 0
3 Curved length of sacrum (mm) M 96-136 119.56 8.61 7.59 <0.001 86.73-138.39 >120.81 12.2
F 90-115 100.95 6.62 81.09-120.81 <86.73 0
4 Tr. Dia Of body of Ist sacral vertebra (mm) M 42-55 49.12 3.27 10.24 <0.001 39.31 - 58.93 >51.93 28.04
F 40-50 42.81 3.04 33-69-51.93 <39.31 0
5 A-P dia. Of body of Ist sacral vertebra (mm) M 26-37 30.04 2.58 1.60 >0.05 22.30-33.78 >35.74 6.8
F 24-32 29.29 2.15 22.84-35.74 <22.30 0
6 Length of ala of sacrum (mm) M 23-33 28.38 2.67 6.06 <0.01 20.37-36.39 <22.52 0
F 26-39 31.67 3.05 22.52-40.82 >36.39 4.8
7 Length of auricular surface (mm) M 55-74 62.54 3.40 12.26 <0.001 52.34-72.74 >64.47 3.10
F 50-60 54.57 3.30 44.67-64.47 <52.34 38.0
8 Sacral index M 90-108 98.21 4.89 17.68 <0.001 83.54-112.86 <96.84 39.2
F 103-131.25 117.84 7.00 96.84-138.84 >112.88 80.1
9 Curvature index M 90.47-98.33 95.72 1.99 9.88 <0.001 89.75-101.69 >100.23 0
F 83.33-97.77 90.72 3.46 80.34-100.23 <84.75 19.0
10 Corporobasal index M 40-53.06 46.54 3.17 9.81 <0.001 37.03-56.05 >50.25 12.2
F 33.2-46.9 40.47 3.26 30.69-50.25 <37.03 9.5
11 Alar index M 44.23 - 59.56 56.1 7.34   <0.001 34.08-78.12 <47.34 2.7
F 62.0-97.5 72.6 8.42 47.34-97.86 >78.12 38.0
12 Index of body of Ist sacral vertebra M 56-72.09 61.73 4.07 8.09 <0.01 49.52-73.94 <53.84 0
F 60-76.09 68.60 4.92 53.84-83.36 >73.94 14.2
13 Auricular index M 50-67.35 59.78 4.06 10.77 <0.001 47.6-71.96 >62.76 13.5
F 44-58.99 51.69 3.69 40.62-62.76 <47.6 14.3

The mean width of the male sacra of Agra region (105.34mm) is similar to observation made by Raju et al. (1981) in the Varanasi region (105.33mm). However, in the females the Varanasi region showed a lesser value than that of Agra region. In the Australian aboriginal females, the maximum width of sacrum was 101.24mm, which is higher than that of males (99.92mm) of the same race (Davivongs, 1963).

The range of the midventral curved length of female sacra falls within the male range in the present study. This is true in the case of Australian aboriginal studied by Davivongs (1963). In the present study in all the cases the mean transverse diameter of body of S1 of male was higher than that of females, supporting the general rule, that the size of the body of first sacral vertebra, should be larger in males than in females. The male bones of the present series showed a higher measurement than the males of Varanasi region (Raju et al., 1981) and the Australian aborigines (Davivongs, 1963).

The famale ranges of anteroposterior & transeverse diameters of body of S1 are narrower than that of males and fall within the corresponding male ranges. The result is that the separation of any female sacrum from the males by the above measurements alone is impossible.

The differences in the length of auricular surface between the males and females is highly significant statistically and the length was more in male than in female supporting the normal description in the text books of Anatomy that the auricular surface for articulation with ilium is shorter in females than that of males. The available literature does not mention about of length of the auricular surface in any of the sacra.

The mean sacral index of the male sacra of the present series (98.21) falls under dolichohieric group (narow sacrum with sacral index upto 99.9). Similar observation was reported by Jana et al. (1988) in their study of sacra of Budhwan region (West Bengal) (mean sacral index of male being 95.7) and Singh et al. (1988) in Jammu region. However, Davivongs (1963) and the Raju et al. (1981) reported that the male sacra of their study fall under sub-platyhieric group.

The mean sacral index of the female bone of the present series (112.62) falls under plathyhieric group, which is similar to the observations of Raju et al. (1981) and Davivongs (1963). Martin (1928) reported that in the European sacrum both male and female means fall into the plathyhieric group, being 112.4 in the male and 114.8 in the female. Any way an attempt to use the sacral index for ethnic discrimination is very doubtful (Davivongs, 1963). However, its importance in sex determination can not be denied since the differences between the males and females are highly singificant, statistically. The mean curvature index of male sacra of the present study (95.72) is slightly higher than that of the observations of Raju et al (1981) and (Davivongs (1963). The same trend was observed in the female bones also.

The mean corporo-basal index of the males (46.54) in the present series is slightly higher than that of the Varanasi region (44.94) studied by Raju et al (1981), while in the case of females the observations are similar in both the regions. The same trend was observed in both the regions as far as the alar index is concerned also. In contrast to the observation of Davivongs (1963) in Australian aborigines and Raju et al (1981) in Varanasi region, the present study revealed a highly significant difference in the index of body of S in both the sexes. The mean auricular index is more in males than females and the difference is statistically highly significant ('p' value < 0.01). A positive correlation was observed between the length of auricular surface and length of sacrum.

Summary & Conclusions:

The present study shows that certain parameters are insignificant as far as the sex determination of sacrum is concerned while certain other parameters are much useful. However, not a single parameter could identify 100% of the bones. Hence, it can be concluded that for the determination of sex of sacrum, maximum number of parameters should be taken to attain 100% accuracy.

References:

  1. Comas J., Charles C., Manual of Physical anthropology (revised and enlarged English edition) Thomas Springfield, Illinois, USA, pp. 415-416 (1961)
  2. Davivongs, V., (1963) : The pelvic girdle of the Australian aborigines- Sex difference and sex determination. American Journal of Physical Anthropology, 21 : 443-455.
  3. Faweet, E. (138) : The sexing of the human sacrum. Journal of Anatomy London. 72 : 638.
  4. Jana, T.K., Koley, T. K., Saha, S. B., Basu, D., and Basu, S.K. (1988) : Variation and sexing of adult human sacrum. Journal of Anatomical Society of India (Proceeding of the Anatomical Society of India). 37 : pp II-III
  5. Jit I. and Singh S. (1966) : Sexing of the adult clavicle, Indian Journal of Medical Research. 54 : 551-571.
  6. Martin (1928) : Cited by Comas, J : Manual of Physical Anthropology. 2nd Edn. Charles. C. Thomes Springfield, Illnois U.S.A. : p 415 (1960)
  7. Rao, C.R. : In advanced statistical method in biometric research. Johnwiley & Sons, Inc. London, pp. 291-296 (1962).
  8. Raju, P.B., Singh, S. and Padamnabhan, R. (1981) : Sex determination and sacrum. Journal of Anatomical Society of India. 30 : 13-15.
  9. Singh H., Singh J. and Bargotra R.N (1988) : Sacral index as observed anthrpometrically in the region of Jammu. Journal of Anatomical Society of India (Proceeding of Anatomical Society of India). 37 : p.1.
  10. Singh S. and Gangrade, K.C. (1968) : Sexing of adult clavicle verification and applicability of demarking point. Journal of Indian Academy of Forensic Science. 7 : 20-30.
  11. Singh, S.P. and Singh, S. (1972) : Identification of sex from the humerus. Indian Journal of Medical Research. 60 10611066.
  12. Singh, S. and Raju, P.B. (1977) : Identification of sex from the hip bone-demarking points Journal of Anatomical Society of India 26 : 111- 117.
  13. Weist, H. (1954) : The auricular surface of Sacroiliac joint & their relation to movement of sacrum. Acta Anatomica 22 : 1-14
  14. Wilder, H.H. A laboratory manual of anthropometry. P. Blakistons sons & Co. Philadelphia. p. 193 (1920) J. Anat. Soc. India 52(2) 132-136 (2003)
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