ORIGINAL ARTICLE Year : 2016  Volume : 2  Issue : 4  Page : 222228 Estimation of Maximum Tibia Length from its Measured Anthropometric Parameters in a Nigerian Population Esomonu Godfrey Ugochukwu, Lukpata Philip Ugbem, Omamuyovwi M Ijomone, Okem Theresa Ebi Department of Anatomy, Faculty of Basic Medical Science, Cross River University of Technology, Okuku Campus, Calabar, Cross River, Nigeria Correspondence Address: Reliable estimation of stature from skeletal remains will continue to play an important role in assessing a variety of forensic anthropological and archaeological issues. In the present study, we studied and collated data on the morphometry of the tibia as well as analyzing its segment that shows significant correlation with its maximum length and consequently formulating linear regression equations for estimating maximum tibia length (MTL) which is specific for the Nigeria population. A total number of 68 intact adult human tibia bones were used (35 right and 33 left). Thirteen anthropometric parameters were measured including the MTL. The mean differences between right and left bones of all the measured parameter were not statistically significant except for the mean shaft circumference. The correlation coefficient between MTL and the bicondylar tibial width (BTW), anteriorposterior intercondylar diameter (APID), anteriorposterior diameter of medial condyle (APDMC), midshaft transverse diameter (MSTD), and distal articular surface length (DASL) were seen to be significant (P < 0.05) only in the right tibia; therefore, the linear regression equations for estimation of MTL from these parameters for the right tibia were also significant (P < 0.05). The results of our study concluded that it is possible to estimate the maximum length of the right tibia from the BTW, APID, APDMC, MSTD, and DASL with relative accuracy. Our study may be useful for forensic investigations for the identification of the remains of unknown bodies in a Nigerian population.
Introduction Estimation of stature from various body parameters has always been of great interest in the field of forensic science and physical anthropology because stature is a major component of the human biological profile which is necessary in the identification of persons who might have fallen victim of mass disaster, mass burial, or even in crimerelated forensic cases. Furthermore, in situ ations involving the profiling of individuals that are missing, the knowledge of stature of the individual is also of great importance. The positive correlation between stature and length of long bones of the human body made it feasible to employ the maximum length of these bones in reconstructing and estimating the stature of unknown individuals.[1],[2],[3] The estimation of bone length from segments of long bones or data obtained from the morphometric parameters of these long bones have also been studied by many researchers. The knowledge of the measurements of these segments has also been employed in determining the maximum length of long bones such as humerus, femur, tibia, and fibula.[4],[5],[6],[7] From these previous studies, it was shown that stature can reliably be estimated from those morphometric features of long bone fragments that correlated well with the long bones length, especially if a linear regression equation has previously been derived for that particular long bone. Although intact long bones are most ideal in estimation of the stature of unidentified individual, in forensic cases where natural disasters present bone fragments, researchers have deemed it necessary to develop regression equations from these bone fragments to use it to estimate the length of the intact long bone from which the stature of the individual can be further derived.[4],[7] Several anthropological reports have always reiterated that estimation of stature is more accurate if regression formulae are population specific. Populationspecific linear regression equations for stature estimation using various body parameters and morphometric study of various long bones have been documented in several studies for the Nigerian population.[5],[8],[9],[10],[11],[12],[13],[14] Esomonu et al., in 2013, presented regression equations for estimation of the length of the humerus from its morphometry in a Nigerian population.[4] In deriving the regression equations for the length of the humerus of the right and left sides, they revealed that both the anatomical neck circumference (ANC) and the midshaft diameter were found to be significant in estimating the maximum length of the humerus; they further reported that on the right side, only the ANC exhibited significant correlation, while on the left side, both the ANC and the most distal point of trochlea humeri exhibited significant correlation.[4] In the present study, we studied and collated data on the morphometry of the tibia as well as analyzing its segment that shows significant correlation with its maximum length and consequently formulating linear regression equations for estimating maximum tibia length (MTL), which are specific for the Nigerian population. Estimating MTL using the linear regression formulae that were derived in the present study will be the most appropriate formulae available at present for the Nigerian population since literature is yet to be available for such estimation in a Nigerian population. The tibia is one of the long bones of the leg. It is the larger of the two leg bones, lying medial to the fibula bone. It is composed of two extremities and a shaft. The proximal extremity articulates with the femur to form the knee joint while the distal extremity and the distal end of the fibula articulate with the talus of the foot to form the ankle joint. Materials and Methods Method of collection of data The tibia bones were obtained from the Anatomy Department Museum of the following universities in Nigeria: Cross River University of Technology, Okuku Campus Enugu State University of Science and Technology Ebonyi State University, Abakaliki. In this study, a total number of 68 intact adult human tibia bones (35 right and 33 left tibia bones) were selected for the study. The rejected bones were either incomplete or had pathological conditions, deformations, or fractured or had parts that were putrefied and disintegrated and so did not make them suitable for this study. The bones that were selected for the study had completely closed epiphyseal plates indicating that they belonged to adults. They were also identified as right or left bones before measurements were taken. Measurement procedures Measurements for the MTL were taken using the osteometric board. Anthropometric tape was used to measure all circumferences, while Digital Vernier Caliper (Sealey Professional Tools TM, United Kingdom; accurate to 0.01 mm) was used to measure the distance between two bony landmarks. Thirteen morphometric parameters were taken into consideration as shown in [Figure 1]. Measurements were made based on standardized methods.[15],[16] The following measurements were obtained:{Figure 1} MTL is measured as the maximum distance from the highest point of the upper part of the tibia to the lowest point of the tibia using the osteometric board Bicondylar tibial width (BTW) is measured as the maximum transverse distance from the lateral side of the lateral condyle to the medial side of the medial condyle using the Digital Vernier Caliper Anteriorposterior intercondylar diameter (APID) is measured as the maximum distance from the anterior intercondylar area to the posterior intercondylar area Anteriorposterior diameter of medial condyle (APDMC) is measured as the maximum anteriorposterior distance of the medial condyle Transverse diameter of medial condyle (TDMC) is measured as the maximum distance from the medial side of the medial condyle to the medial intercondylar tubercle of intercondylar eminence Anteriorposterior distance of lateral condyle (APDLC) is measured as the maximum anteriorposterior distance of the lateral condyle Transverse diameter of lateral condyle (TDLC) is measured as the maximum distance from the lateral side of the lateral condyle to the lateral intercondylar tubercle of the intercondylar eminence Intercondylar distance (ID) is measured as the maximum distance from the medial intercondylar tubercle to the lateral intercondylar tubercle Proximal shaft diameter (PSD) is measured as the maximum transverse distance of the proximal part of the shaft just inferior to the tibial tuberosity Midshaft transverse diameter (MSTD) is measured as the maximum transverse distance of the midpoint of the shaft Mid shaft circumference (MSC) is measured as the maximum circumference at the mid length of the shaft Distal shaft diameter (DSD) is measured as the maximum transverse distance of the lower end of the shaft Distal articular surface length (DASL) is measured as the maximum transverse distance of the inferior surface of the tibia. Statistical analysis Data obtained from anthropometric measurements were analyzed by descriptive statistics and expressed as mean ± standard deviation (SD). A comparison of differences between left and right tibia was performed using Student's ttest. Pearson's correlation coefficient (r) was used to express the relationship between the maximum length of the tibia and other parameters. Furthermore, linear regression analysis was performed and regression equation formulated for the prediction of the maximum length of the bone from the other parameters. Statistical significances in all cases were noted at P < 0.05. GraphPad Prism 5 (version 5.03 GraphPad Inc., USA) was the statistical software used for analysis. Results The results of this study are presented as descriptive statistics (mean ± SD), with their respective standard errors of estimate (SEE) for the 13 different anthropometric parameters for the right and left tibia separately [Table 1] whereas [Table 2] shows the morphometric values of the tibia parameter irrespective of the side of the Tibia bone. The mean maximum length of the right tibia was 40.30 ± 4.32 cm while that of the left tibia was 40.80 ± 3.91 cm. The mean differences of all the measured anthropometric parameters were not statistically significant except for the MSC. All SE of estimates were well below 1.0 [Table 1].{Table 1}{Table 2} The correlation coefficient between MTL and other tibia morphometric parameters is shown in [Table 3]. For the right tibia, MTL was significantly (P < 0.05) correlated with the BTW, APID, APDMC, MSTD, and DASL. However, for the left tibia, the MTL showed no significant correlation at P < 0.05. When the values were pooled irrespective of sides, BTW, APID, APDMC, MSTD, and DASL correlated significantly with MTL (P < 0.05).{Table 3} The linear regression equations for estimation of MTL from its measured parameters are shown in [Table 4]. For the right tibia, the parameters which showed significant correlation with MTL also presented significant (P < 0.05) linear regression equations for the estimation of the MTL. These parameters include BTW, APID, APDMC, MSTD, and DASL. For the left tibia, since none of the corresponding tibia anthropometric parameters significantly correlated with its MTL, none of the linear regression equations derived was statistically significant at P < 0.05. Irrespective of the side, the same tibia parameters that showed significant correlation with the right tibia MTL also correlated significantly (P < 0.05) with the pooled MTL value. Thus, the linear regression equation derived from the pooled values irrespective of the side for the BTW, APID, APDMC, MSTD, and DASL was statistically significant.{Table 4} Discussion The tibia is one of the long bones of the human body whose role in anthropological research cannot be overemphasized due to its resistance to disintegration and its ability to still retain its anatomical form long after death.[17],[18],[19] Tibia bone morphometric parameters are also considered in forensic cases where stature is needed to confirm the identity of unknown and unclaimed human remains; this is carried out by establishing linear regression equations in relation to the maximum length of the tibia.[20],[21],[22] In the present study, the morphometric tibia parameters were correlated with the MTL with the view of establishing a linear regression equation which can be employed in forensic cases whereby the tibia bone retrieved is fragmentary. Regression analysis is an ideal method for establishing the relationship that exists between the length of the long bones and the stature of individuals and between the measured anthropometric parameters of the long bone fragments and their maximum length.[23] It is a known fact that the importance of the linear regression formulae that were designed by Trotter and Gleser for the estimation of an individual stature cannot be overemphasized [24] Nevertheless, it has been reported that all regression formulae employed in stature estimation should be populationspecific.[25],[26] As such, the regression formulae generated in the present study are meant only for the Nigerian population although their application and comparison with that of other population are relevant for comparison purposes in forensic anthropology and human anatomy. In forensic cases, long bone length is also employed in the estimation of an unknown individual's stature which is very essential in the assessment of health, sexual dimorphism, and the general body size that trends along with given populations.[27] The estimation of living stature using linear regression equation has successfully been done with the tibia bone length.[20] Thus, the estimation of the stature of an unknown individual from the bones can help in the identification of missing persons from recovered bony remains.[28] In our study, the data obtained from the morphology of the tibia were sexpooled although it has been advocated by anthropologists that the sex of the individual must always be considered to obtain higher accuracy in stature estimation.[29],[30] Petersen's study revealed that on the contrary, the differences of the femur lengths were not dependent on sex;[31] hence, based on his report and the fact that the gender of the available tibia was not known, the present study was carried out on tibia bones of unknown gender. Several authors have derived linear regressions to estimate the maximum length of long bones from the measurement of its fragments in different populations.[4],5,[32],[33],[34] In the present study, regression equations were derived to estimate the maximum length of the tibia from the measured parameters of the right tibia and the pooled values irrespective of the side from the BTW, APID, APDMC, MSTD, and DASL values of the parameters. These parameters showed significant correlation with the MTL but the maximum length of the left tibia showed no significant correlation with any of the measured parameters as such none of the linear regression equations derived for the left tibia from its measured parameter was statistically significant, and therefore, none of the equations can be relied on for the estimation of its maximum length in a Nigerian population. For the Kenyan population, Mandela et al. derived regression equations to measure the length of the tibia from dimensions of its distal articular facets using the right and left sides separately. Their study did demonstrate moderate correlations between the dimensions of the distal tibia and its length whereby positive correlation was noted when the tibia length was compared to the width of the tibial plafond, the breadth of the medial malleolus, and the height of the fibular incisura.[35] However, these morphometric parameters were not considered in the present study. The MTL was estimated from the linear regression equations and compared with the observed mean MTL in the present study [Table 5] and it was observed that the difference between the estimated MTL from the observed MTL was not significant (P< 0.05). It implies that the estimation of MTL from the BTW, APID, APDMC, MSTD, and DASL using linear regression equations can only be reliable with the right tibia or when the tibia is considered irrespective of the side. Thus, the present study provides regression formulae for estimation of the maximum right tibia length from its measured parameters. This suggests that when either of the BTW, APID, APDMC, MSTD, and DASL are available in any fragmentary tibia bone in a Nigerian population, then the formulae can be used to establish the MTL.{Table 5} From the statistical analysis of the morphometry of the tibia, the mean length of the right side tibia is 40.30 ± 4.32 cm and that of the left side tibia is 40.80 ± 3.91 cm [Table 1]. When both sides were considered irrespective of sides, the mean was found to be 40.50 ± 4.08 cm [Table 2]. These values are higher than the reported value for the Kenyans tibia length.[35] In that study, the authors revealed a mean value of 38.2 ± 2.75 cm for the MTL. A study on the Central Indian population also revealed a value of 371.30 ± 23.20 mm for the right tibia and a value of 379.41 ± 18.90 mm for the left tibia. Both values were lower than the reported values for the right and left tibia in the present study.[22] No statistically significant difference was found in the mean MTL between the right and left. In addition, of the other 12 parameters measured, only the MSC showed statistically significant difference between the right and left tibia. This similarity between the right and left tibia values was also noted for the Central Indian population.[22] Of the three anthropometric indices calculated by these authors, which include crosssectional index, cnemicus index, and lengththickness index, only the variation in the crosssectional index values showed statistically significant difference when compared between sides. Conclusion Reliable estimation of stature from skeletal remains will continue to play an important role in assessing a variety of forensic anthropological and archaeological issues. Most investigators rely on regression techniques to estimate stature from long bones because of their simplicity; however, if skeletal remains are in fragments, stature estimation can still be obtained by first deriving the length of the bones from the available fragments. The results of our study concluded that it is possible to estimate the maximum length of the right tibia from the measures of its BTW, APID, APDMC, MSTD, and DASL with relative accuracy. Our study may have direct applications in forensic, anthropometric, and also archaeological investigations for the identification of the remains of unknown bodies using linear regression equations in a Nigerian Population. Further study should be encouraged as these are just preliminary data formulae available for the Nigerian population as no other literature exist for estimation of the MTL for the Nigerian Population. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. References


