Osteology: Estimating Femur Length from the Diameter of the Femoral Shaft

School of Biological & Earth Sciences BIEGN3005 Honours Project March 2010 Student name: Stephen Dempsey Supervisor name: Professor Alan Turner Estimating femur length from the diameter of the femoral shaft Stephen Dempsey BIEGN300 Honours Project Person Number: 343106 Submission Date: 5th March 2010 Abstract Bone lengths can be used to provide stature estimations in case of unidentified skeletal remains, an important tool in forensic and bioarchaelogical cases. Where the bones are broken or fragmented, regression equations can be used to estimate total bone length from its fragments, which in turn can be used to estimate stature.The aim of this study was to test 2 new measurements of the femoral shaft to see if they could be used as predictors of maximum femoral length. The minimum transverse femoral shaft diameter and the minimum anterior-posterior femoral shaft where measured on a small sample of an archaeological population from Poulton, Cheshire, along with the maximum femur len gth for each sample. Simple linear regression analysis was performed and the results showed that the minimum transverse femoral shaft diameter correlated significantly in both males (R2=. 635, p=0. 006) and females (R2=0. 8, p=? 0. 001) with maximum femur length. The minimum anterior-posterior femoral shaft diameter showed no significant correlation with maximum femur length. Subsequently, regression equations were presented for the significant correlations. Further research is needed to validate the results and to improve the accuracy of the method. 1. Introduction The role of a forensic anthropologist in forensic and archaeological cases is to establish demographics (population affinity, age, sex and stature), time since death and cause of death from an individual’s remains (Chibba et al, 2006).The use of stature as a biological characteristic of identity can significantly contribute to the identification of unknown skeletal remains. Numerous areas of the skeleton have been used to try and determine an individual’s living height such as the upper limb bones (Rao et al. 1989), lower limb bones (Trotter and Gleeson, 1952), the metatarsals (Cordiero et al, 2009) and the skull (Ryan and Bidmos, 2007). Hauser et al. (2005) provide a good review of the past research in the area of stature estimation. One of the methods used in the estimation of stature is the formulation of regression equations from measurements of various bone lengths.Pearson (1899) was the first to derive regression equations for estimating stature, and since then it has grown to be the method of choice among most anthropologists. Many of the methods used to approximate stature require complete or near complete bones, so consequently few studies have been done on incomplete or fragmentary bones (Bidmos, 2008). Forensic anthropologists are often confronted with fragmented bones and in these cases it is impossible to derive regression equations directly from bone length (Rao et al. 9 89). Wright and Vasquez (2003) state the problems they faced in Guatemala in which they were often unable to estimate stature from bone length due to the rapid deterioration of bone in the tropical environment. This is only one of many factors that lead to the all too frequent recovery of broken or fragmented remains. Therefore it is beneficial to have equations available for bone length or stature derived from measurements of smaller segments or landmarks on the chosen bone.The femur is the favoured bone of use among anthropologists in estimating stature, due to its high correlation with height in addition to the fact that it is one of bones most often recovered (Simmons et al. 1990). A number of measurements of the femur have already been reported to have good correlations with femur length. Many of these measurements focus on the proximal and distal ends of the femur such as the upper epicondylar length, epicondylar breath, vertical neck diameter and the bicondylar breathe (Braue r, 1988), yet few have focused on measurements of the femoral shaft.This pilot study looks to test the validity of 2 measurements from the femoral shaft as predictors of maximum femoral length. The points of reference chose on the femur are the minimum transverse femoral shaft diameter (TRD) and the minimum anterior-posterior diameter (APD) of the femoral shaft. The samples being used are that of an archaeological population recovered from a medieval cemetery in Poulton, Cheshire. The aim is to use linear regression analysis to test the assumption that there is a significant correlation between these measurements and the maximum femoral length.A further aim is to produce regression equations that can be used on other skeletal remains from the Poulton collection for estimating maximum femur length. 2. Materials and Methods 2. 1 Samples The samples used in this study were obtained from the Poulton collection housed at Liverpool John Morres University. Due to the small size of the coll ection at present and the poor condition of some of the bones, a total number of 18 left sided femora were selected for use in the study. These femora were chosen on the basis of completeness and measurability.All the samples were obtained from adults skeletal remains and the number of male and females femora was 10 and 8 respectively. 2. 2 Measurements The following 3 measurements were taken on each of the 18 samples: i. Maximum length of the femur (MAXL) ii. Minimum anterior-posterior femoral shaft diameter (APD) iii. Minimum transverse femoral shaft diameter (TRD) The MAXL measurement was taken as described by Brauer (1988). The APD and TRD measurements were taken as described by Ziylin and Mursid (2002). The MAXL was measured using an osteometric board.The APD and TRD were measured using a sliding callipers with an accuracy of 0. 1 mm. Linear regression analysis was carried using the SPSS statistic program to see if any correlation existed between the measurements taken of the f emoral shaft (APD and TRD) and the maximum length of the femur. All analysis was carried out separately for males and females on the advice of Trotter and Gleser (1952) who state the specificity of such measurements in relation to sex. 3. Results The descriptive statistics for males and females are shown in Table 1. Males showed the highest mean values of each of the 3 measurements taken.Males also showed the higher standard deviations in respect to MAXL and APD, with females showing a higher standard deviation for TRD. Table 1 Descriptive statistics for measurements of male and female left femora. All descriptive values are given in mm. Measurements| Male| Female| | N| Mean| Std. dev| N| Mean | Std. dev| MAXL| 10| 466. 60| 16. 965| 8| 429. 13| 11. 643| TRD| 10| 27. 910| 1. 365| 8| 24. 725| 1. 752| APD| 10| 28. 190| 2. 497| 8| 27. 138| 1. 840| Table 2 shows the results of the linear regression analysis that was performed. Both APD and TRD were regressed against MAXL according to sex .The analysis showed that the variable APD showed no significant correlation to MAXL for males (R2=0. 154, P=0. 262) or females (R2=0. 044, P=0. 619). TRD provided more positive results showing a moderate significant correlation in respect to males (R2=0. 635, P=0. 006), and a strong significant correlation in respect to females (R2=0. 88, P=0. 01 (Table 2) and the standard error of the estimated being