



ORIGINAL ARTICLE 

Year : 2022  Volume
: 71
 Issue : 1  Page : 3033 

Estimation of length of femur from its distal segment
Aswathy Maria Oommen, Suja Robert Joseph Sarasammal, Sheena Kalyani Sukumaran
Department of Anatomy, Government Medical College, Thiruvananthapuram, Kerala, India
Date of Submission  17Sep2020 
Date of Acceptance  27Oct2021 
Date of Web Publication  17Mar2022 
Correspondence Address: Dr. Suja Robert Joseph Sarasammal Ebenezer, JNPRA 76, Jayaprakash Lane, Kudappanakunnu, Thiruvananthapuram, Kerala India
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/jasi.jasi_190_20
Introduction: The stature of an individual, one of the key elements of identification, can be calculated from the length of long bones in the body, of which the femur has the highest correlation with stature. Many a times, forensic anthropologists have to identify unknown dead bodies from fragments of bones that are available. Studies have proven that the total length of a bone can be estimated from fragments using populationspecific regression equations. In the present study, the objective was to estimate the total length of the femur (TFL), in an Indian population, from measurements of its distal segment, using regression equations. Material and Methods: One hundred and twentyone intact adult femurs were studied. The TFL and four variables from its distal segment were measured. Linear regression analysis was performed, and regression equations were derived to calculate the TFL from each of the variables. Results: The mean TFL was 41.9 ± 3.4 cm. All the four parameters of the distal segment showed a significant positive correlation with the total femoral length (P < 0.001), and of these, the width measured between the two epicondyles showed the maximum correlation. Multivariate and univariate regression equations were derived to estimate the TFL from these variables. Discussion and Conclusion: The TFL can be reliably calculated from the measurements of the distal fragments. These measurements can be used by forensic anthropologists for the estimation of the stature of an unknown individual.
Keywords: Distal fragments, femur, linear regression analysis, regression equations
How to cite this article: Oommen AM, Joseph Sarasammal SR, Sukumaran SK. Estimation of length of femur from its distal segment. J Anat Soc India 2022;71:303 
Introduction   
Age, sex, ancestry, and stature are the four elements of forensic anthropology used to establish the identity of an individual.^{[1]} Stature can be estimated from different bones such as the limb bones, vertebrae, sternum, and skull.^{[2],[3],[4],[5],[6],[7],[8],[9]} It is best calculated from the length of long bones of lower limbs, and the femur is the better option.^{[10]} Reconstruction of the length of the femur from fragments of bone that are recovered from scenes of crime, accidents, and burial grounds is an essential step in the estimation of stature in forensic investigations.^{[9]} Physical characteristics of people of different races and ethnicity are different^{[3],[10],[11]} and hence regression formulae used for estimating the length of femur from fragments must be population specific. In this study, we aimed to drive regression equations for the reconstruction of the length of femur from its distal fragments in an Indian population.
Material and Methods   
This study was approved by the Institutional Review Board and Human Ethics Committee of the institution (IEC. No. 11/05/2017/MCT dated November 03, 2017). It was conducted as a crosssectional study using 121 intact adult femora (right54 and left67). Bones with any gross deformities or damages were not included in the study. Age, ethnicity, and sex were not known. The length of femur was measured using an osteometric board, and all other measurements were taken with digital vernier calipers.
Five variables were measured [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d:  Figure 1: (a) The measurement of the distance between the two epicondyles (WE). (b) The measurement of the width of the intercondylar notch (WIC). (c) The measurement of the anteroposterior length of medial condyle (MAP). (d) The measurement of the anteroposterior length of lateral condyle (LAP)
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 TFL  Total length of femur. It was measured from the highest point on the head of femur to the lowest point on the condyles
The other four measurements were taken from the distal end of femur.
 WE  Width of the lower end of femur, measured between the two epicondyles
 MAP  Anteroposterior length of the medial condyle, measured between the most convex points, anteriorly and posteriorly
 LAP  Anteroposterior length of the lateral condyle, measured between the most convex points, anteriorly and posteriorly
 WIC  Width of the intercondylar notch.
Quantitative variables were expressed as a minimum, maximum, mean, and standard deviation. Comparison of quantitative variables between the right and left was analyzed using independent sample ttest. P < 0.05 was considered statistically significant. The relationship between TFL and each of the other four quantitative variables was analyzed by Pearson's correlation analysis. P < 0.05 was considered statistically significant. Linear regression formulae were derived to estimate TFL from measurements of the different variables. Data analysis was performed using trial versions of the IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp.
Results   
The total length and the dimensions of the different variables of 121 femora (54right and 67left) were measured, subjected to statistical analysis, and compared. Comparison of quantitative variables between right and left showed that the difference was statistically insignificant [Table 1]. None of the variables qualified for discriminant analysis. The mean TFL was 41.9 ± 3.4 cm. Pearson's correlation done to analyze the correlation between TFL and each of the other four quantitative variables was statistically significant (P < 0.05). Descriptive statistics of the measurements of the variables of femur are tabulated in [Table 2].  Table 1: Independent sample ttest to compare the quantitative variables of the right and left femora
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Linear regression analysis was done to establish the relationship of TFL with the different variables at the lower end of femur. All the four parameters of the distal segment that were measured showed a significant positive correlation with the TFL (P < 0.001). Of these, WE showed the maximum correlation. Linear regression equations were derived for the estimation of the length of femur from the measured variables. Correlation coefficients ranged from 0.338 to 0.693, with WE showing the highest and WIC the least values [Table 3]. Regression model from multivariate analysis reveals that R^{2} is 0.584, i.e., 58% variation in TFL could be explained by these measurements.  Table 3: Linear regression analysis to estimate the total length of femur from the variables measured from the distal segment of femur
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Multivariate equation: TFL = 12.268+ (1.893 × WE) + (1.356 × MAP) + (1.684 × LAP) − (.226 X WIC)
Univariate equations:
 TFL = 15.672 + (3.767 × WE)
 TFL = 21 + (3.905 × MAP)
 TFL = 19.782 + (3.922 × LAP)
 TFL = 35.15+ (3.125 × WIC).
Discussion   
Estimation of the antemortem stature of an unknown individual is an important aspect of forensic anthropological investigations and was described way back in 1878 by Thomas Dwight in his essay on “Identification of the human skeleton.”^{[12]} Later in 1956, Georges fully developed the “anatomical method” and used all bones from the skull to calcaneum to reconstruct the stature of an individual.^{[13]} Karl Pearson developed the first formal stature regression formula to estimate stature.^{[14]} A method of estimating stature from long bones was also developed by Totter and Glesser.^{[10],[15]} They derived regression equations from the length of long bones and calculated stature (mathematical method). There is the most commonly used method for stature estimation.^{[8],[10]}
Airplane crashes, bomb blasts in crowded locations, mass fatalities and natural disasters, exhumation of skeletonized human bodies or individual parts that are days or even months old are not a rarity nowadays. Usually, an intact skeleton is not obtained from the scene of an accident or crime, and the actual length of bones must be estimated from the fragments of bone that are obtained. Assuming that the height of an individual is dependent on the length of long bones, stature is estimated from the projection of length of long bones using regression formulae specific for that population for identification of the individual.
In the present study, measurements were taken from the distal segment of femur. The TFL was also measured. There is a difference in the lengths of the right and left side bones. However, studies have shown that the difference in length of femur of the right and left sides is statistically insignificant.^{[3],[16],[17]} A comparison between the variables of the right and left sides in the present study also showed that it was not statistically significant. The TFL measured in the present study and other studies are shown in [Table 4]. Steele and McKern studied long bones such as femur, tibia, and humerus in a sample obtained from archaeological sites in the Southeastern United States.^{[18]} Regression formulae were established to obtain the length of the long bones from various fragments. Jubilant Kwame Abledu worked on a Ghanaian population to reconstruct the length of femur.^{[9]} Measurements were taken from both proximal and distal fragments. Of all the segments measured, subtrochanteric transverse diameter measured between the medial and lateral surfaces at the proximal end of the diaphysis just below the lesser trochanter was found to be the best estimator of femoral length. Bidmos MA did a study on complete skeletons obtained from a South African population of European descent to reconstruct stature from fragmentary femora.^{[23],[25]}  Table 4: Comparison of the total length of femur in the different studies
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Studies were also conducted in the Indian population. Sandeep Singh calculated femoral length from measurements of the intertrochanteric crest in a Central Indian population.^{[20]} Solan's work was on femora obtained from a South Indian population.^{[21]} Total femoral length and various dimensions from the proximal and distal end of femur were measured. Parmar et al. study was also on the reconstruction of femoral length from both proximal and distal fragments. The sample was obtained from Rajasthan, India.^{[22]} Regression equations were derived for different variables, including the distance between medial and lateral epicondyles, as in the present study. In all these studies, the length of femur measured was higher than values obtained in the present study, reinforcing the fact that the length of bones is population specific.
Shroff et al. measured the length of the femur from various fragments, and results obtained for the length of femur were comparable to the present study.^{[19]} Mukhopadhyay correlated the maximum length of femur from epicondylar breadth in a population of West Bengal, India. The results were consistent with the present study.^{[24]}
Linear regression equations were derived from the variables to predict the length of femur. There is a significant positive correlation between each of these measurements and TFL. The error estimates of the linear regression equations were low (2.466–3.222) indicating that the difference between the calculated and actual TFL was comparatively low. Compared to all the other parameters, WE were the best parameter to assess TFL. The regression equations of this study and other similar studies that have measured variables from the fragments of femur are shown in [Table 5].  Table 5: Comparison of linear regression equations derived for calculating total length of femur from the epicondylar breadth (measured between the medial and lateral epicondyles of femur)
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Conclusion   
From this study, regression equations were derived to calculate the length of femur from fragments of its distal segment that may be recovered from a scene of crime or accidents. From the calculated length of femur, it is possible to obtain the height of the individual using formulae that are available. It will be quite appropriate to conclude that these formulae will prove to be extremely helpful to forensic anthropologists and archaeologists as well as anatomists everywhere.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
