Validation of a radiographic method to establish new fetal growth standards: radio-anatomical correlation

In forensic medicine, specialists might face difficulties when estimating age at death from fetal remains. Depending on the state of preservation, this age assessment is essentially based on the diaphyseal size of long bones. In a previous work, for the measurement of fetal femoral ossified shafts, we already established a simple and reliable method using a radiographic protocol. Since we previously stated that radiographic measurement values were closer to real anatomical size than ultrasonographic ones, in the present study we decided to check the importance of the difference between radiographic and anatomical measurements. Therefore, we dissected 30 pairs of fetal femurs and compared the difference between the two kinds of measurements (in percentages). This difference seemed to be slight (4.027%), but it was large enough to entail significant differences (p < 0.001). In order to provide a correction factor for radiographic measurements, we established a linear regression formula, which was tested on another sample of 30 pairs of dissected femurs. As a consequence of the good results, we improved the linear regression using a powerful statistical tool: the bootstrap. Finally, we obtained a simple equation that allowed us to figure out the real anatomical size with an R2 of 99% and a mean relative difference of 0.153% (with a standard error of 0.252 mm, and therefore a 95% confidence interval with limits of -0.35 and 0.657 mm). This difference did not entail any significant differences (p = 0.498), and therefore, we concluded that with the proposed correction, radiographic measurements can easily be used by forensic specialists in their daily tasks or to establish new growth standards in order to best fit their population of interest.     

Fetal visceral maturation: a useful contribution to gestational age estimation in human fetuses

With regard to the law, estimating fetal age is essential to assess viability (after 20 weeks according to the WHO) and the proposed methods generally use long bone measurements. Here, we evaluated the accuracy of soft tissue maturational stage and compared it with long bone measurements. First, eight kinds of tissues or organs from 448 fetuses with known medical history were studied (macroscopically or histologically). We clearly demonstrated that adrenal glands and skin were very good age indicators, because some characteristics appeared only after 20 weeks. We established a linear regression with a 95% confidence interval of +/- 2.9 weeks. Second, we applied our original formula using femur measurement and we combined soft tissues and bones in a multiparametric regression. The confidence interval was reduced to +/- 2.5 weeks. We conclude that the pathologist must use both histological and anthropometric data to determine fetal age as accurately as possible.     

Is the length of the sternum reliable for estimating adult stature? A pilot study using fresh sterna and a test of two methods using dry sterna

Stature estimation is one of the four attributes of the biological profile obtained from human skeletal remains. The length of the long bones has been consistently used to estimate stature from regression equations, but these may be useless when dealing with fresh or decomposed mutilated remains. Until recently, there was no consistent assessment of the reliability of measurements of the sternum for stature estimation. The purpose of this paper is to test previously developed regression formulae for stature based on measurements of the dry sternum and to assess the reliability of measurements of the fresh sternum in estimating stature. The formulae developed by Menezes et al. and Singh et al. were applied to a sample of 5 known stature skeletons from the identified human skeletal collection curated at the National Museum of Natural History, in Lisbon, Portugal. Testing of these formulae showed that estimated stature confidence intervals do not allow discrimination between individuals with similar stature. The length of the fresh sternum was measured on a sample of 45 male individuals autopsied at the National Institute of Legal Medicine - North Delegation (Porto, Portugal). Cadaver length was regressed on sternum length and a simple linear regression formula was obtained. The regression model provided a 95% confidence interval of 13.32 cm and a correlation coefficient of only 0.329. Compared to other studies, regression formulae based on the length of the sternum provided considerably larger standard errors than that based on long bone lengths. These results suggest that the length of the sternum has limited forensic value and relatively low reliability in estimating stature from mutilated human skeletal remains, either skeletonized or fresh.     

Fetal Age Estimation Using Orbital Measurements: 3D CT-Scan Study Including the Effects of Trisomy 21

Abstract:  This study evaluates a new method of fetal age estimation based on orbital measurement and including the potential trisomy 21 of the fetus. Six orbital and one facial CT-scan measurements were taken on 71 fetuses ranging from 14 to 41 weeks of gestational age. Forty-eight fetuses were "normal" and 23 fetuses presented the Down syndrome (trisomy 21). The anatomy/imagery correspondence was evaluated comparing our results to those obtained by direct bone measurements on the same fetuses and revealed no significant differences between the two kinds of measurements. Moreover, a multiple linear stepwise regression was realized to estimate fetal age and showed that the "trisomy 21 parameter" is not conserved in the final determination model. Therefore, we conclude that the good radio-anatomical correspondence offers an interesting alternative to direct bone measurement (necessitating dissections) and allows a reliable fetal age determination, whatever is the trisomy 21 condition of the fetus.     

Postmortem assessment of fetal diaphyseal femoral length: validation of a radiographic methodology

Depending on the general condition of fetal remains, forensic specialists might face difficulties concerning age estimation. Reference tables and regression equations are helpful devices in this task, although they are generally applied for complete fetuses or fetal remains including soft tissues. However, the problem of age estimation stays for osseous remains, both for entire bones and ossified parts, since most of the reference tables come from ultrasonographic measurements, which are not easily reproducible on fetal osseous remains. Furthermore, the ultrasonographic measurements contain slight errors in comparison to the real anatomical ones. This study describes a radiographic protocol and a measurement technique that facilitate and improve bone measurements, and therefore, facilitate age estimation, too. A qualitative criterion, namely a clear-cut bony endplate, was defined and tested. Its reliability (repeatability and reproducibility) turned out to be good, showing nonsignificative differences to the threshold of 0.05, with average errors of 0.26 and 0.44 mm respectively. Moreover, concerning the test of eventual size differences between the right and left femurs showed a P value < 0.0001. The test of the qualitative criterion was based on the comparison of the radiographic in situ femur measurements and the radiographic measurements of the same bones after dissection. The results were satisfactory, since an average error of 0.58 mm was obtained, which did not give any significant differences to the threshold of 0.05. It was concluded that this methodology provides an easy and precise new measurement tool for forensic practice, and can allow us to establish some nonultrasonographic tables, which fit our population.     

Developing permanent tooth length as an estimate of age.

Developing teeth are widely used to predict age in archaeology and forensic science. Regression equations of tooth length for age is a direct method, however, data for permanent teeth is incomplete. The aims of this study were: (a) to calculate regression equations predicting age from tooth length of all permanent teeth from birth to maturity, and (b) to evaluate the difference between radiographic and actual tooth length. The sample studied (N = 76, age range 0 to 19 years) was the Spitalfields juveniles of recorded age-at-death. Tooth length was measured from incisal tip to developing edge of crown or root of 354 dissected teeth. Data for upper and lower teeth were combined except for the lateral incisor. The least squares regression method was used to analyze the data for each tooth type; age being regressed against tooth length for prediction. For most tooth types, growth followed an S-shaped (polynomial) curve with initial fast growth and a further growth spurt around the time of mid root formation. No difference was found between radiographic and true tooth length. These regression equations provide an easy method of predicting age from any developing permanent tooth by measuring tooth length from isolated teeth or from unmagnified, undistorted radiographs.     

Bidimensional Data Allow for Better Age Estimation on Immature Specimens than Unidimensional Data: A Preliminary Study on the Ilium

Most biometric age estimation methods used in anthropological and forensic science for juveniles are based on unidimensional measurements (length or width). Here, a new method using bidimensional data was tested. A 3D morphometric analysis was performed on 108 CT scans of ilium bone of juveniles (from 20 gestational weeks to 12 years old). The sample was divided into training and validation groups. Best predictors were determined by comparing the efficiency of each variable (length, width, area, and module: a product of length and width). We established linear and polynomial regressions for each parameter for both sides. Applying the equations to the validation sample showed no significant difference between real and predicted ages. For age estimation, the area and module parameters yielded better results than unidimensional measurements. The results from this preliminary study were highly conclusive, and it would be interesting to extend the work, covering larger samples, and other bones.     

Dental age estimation and third molars: a preliminary study

The aim of the present investigation was to reconstruct the chronological age based on the dental developmental stages of third molars evaluated on orthopantomograms. A total of 1175 orthopantomograms were assembled from patients of Caucasian origin between 16 and 22 years of age. Each third molar present was scored by two observers according to a 10-stage developmental scale. The kappa statistics measured the intra- and inter-observer reliability. The general statistical analysis was based on multiple regression analysis in order to obtain multiple regression formulas for dental age estimation based on the number of third molars present on the evaluated orthopantomogram. No regression models were statistically significant when there was only one-third molar present because of the relatively small number of orthopantomograms that fitted this criterion. A strong agreement was found between the intra- and inter-observer measurements. The statistical analysis revealed both for males and females high Pearson correlation coefficients between contralateral third molars and smaller coefficients between antimeres. The obtained multiple regression formulas are only applicable in certain specified conditions, for instance when four third molars are present the following formulas should be used in a Caucasian male "age=10.2000+0.5122UL+0.5273LL" (developmental stage of upper and lower left third molars) or in case of a female "age=13.6206+0.1933UR+0.5080LR" (developmental stage of upper and lower right third molars). This investigation revealed that the chronological age of a Caucasian individual may be estimated based on regression formulas with a S.D. of 1.52 or 1.56 years for males and females, respectively, when all four third molars are present.     

Age estimation of adults from dental radiographs

Previous studies have shown that with advancing age the size of the dental pulp cavity is reduced as a result of secondary dentine deposit, so that measurements of this reduction can be used as an indicator of age. The aim of the present study was to find a method which could be used to estimate the chronological age of an adult from measurements of the size of the pulp on full mouth dental radiographs. The material consisted of periapical radiographs from 100 dental patients who had attended the clinics of the Dental Faculty in Oslo. The radiographs of six types of teeth from each jaw were measured: maxillary central and lateral incisors and second premolars, and mandibular lateral incisors, canines and first premolars. To compensate for differences in magnification and angulation on the radiographs, the following ratios were calculated: pulp/root length, pulp/tooth length, tooth/root length and pulp/root width at three different levels. Statistical analyses showed that Pearson's correlation coefficient between age and the different ratios for each type of tooth was significant, except for the ratio between tooth and root length, which was, therefore, excluded from further analysis. Principal component analyses were performed on all ratios, followed by regression analyses with age as dependent variable and the principal components as independent variables. The principal component analyses showed that only the two first of them had significant influence on age, and a good and easily calculated approximation to the first component was found to be the mean of all the ratios. A good approximation to the second principal component was found to be the difference between the mean of two width ratios and the mean of two length ratios, and these approximations of the first and second principal components were chosen as predictors in regression analyses with age as the dependent variable. The coefficient of determination (r²) for the estimation was strongest when the ratios of the six teeth were included (r² = 0.76) and weakest when measurements from the mandibular canines alone were included (r² = 0.56). Measurement on dental radiographs may be a non-invasive technique for estimating the age of adults, both living and dead, in forensic work and in archaeological studies, but the method ought to be tested on an independent sample.     

Age-related factors in the relationship between foot measurements and living stature and body weight

The measurements of feet and footprints are especially important in forensic identification, as they have been used to predict the body height and weight of victims or suspects. It can be observed that the subjects of forensic-oriented studies are generally young adults. That is to say, researchers rarely take into consideration the body's proportional changes with age. Hence, the aim of this study is to generate equations which take age and sex into consideration, when stature and body weight are estimated from foot and footprints dimensions. With this aim in mind, we measured the stature, body weight, foot length and breadth, heel breadth, footprint length and breadth, and footprint heel breadth of 516 volunteers (253 males and 263 females) aged between 17.6 and 82.9 years using standard measurement techniques. The sample population was divided randomly into two groups. Group 1, the study group, consisted of 80% of the sample (n = 406); the remaining 20% were assigned to the cross-validation group or Group 2 (n = 110). In the first stage of the study, we produced equations for estimating stature and weight using a stepwise regression technique. Then, their reliability was tested on Group 2 members. Statistical analyses showed that the ratios of foot dimensions to stature and body weight change considerably with age and sex. Consequently, the regression equations which include these variables yielded more reliable results. Our results indicated that age and sex should be taken into consideration when predicting human body height and weight for forensic purposes.     

Sex estimation in a modern American osteological sample using a discriminant function analysis from the calcaneus

Reliable methods for sex estimation during the development of a biological profile are important to the forensic community in instances when the common skeletal elements used to assess sex are absent or damaged. Sex estimation from the calcaneus has potentially significant importance for the forensic community. Specifically, measurements of the calcaneus provide an additional reliable method for sex estimation via discriminant function analysis based on a North American forensic population. Research on a modern American sample was chosen in order to develop up-to-date population specific discriminant functions for sex estimation. The current study addresses this matter, building upon previous research and introduces a new measurement, posterior circumference that promises to advance the accuracy of use of this single, highly resistant bone in future instances of sex determination from partial skeletal remains. Data were collected from The William Bass Skeletal Collection, housed at The University of Tennessee. Sample size includes 320 adult individuals born between the years 1900 and 1985. The sample was comprised of 136 females and 184 males. Skeletons used for measurements were confined to those with fused diaphyses showing no signs of pathology or damage that may have altered measurements, and that also had accompanying records that included information on ancestry, age, and sex. Measurements collected and analyzed include maximum length, load-arm length, load-arm width, and posterior circumference. The sample was used to compute a discriminant function, based on all four variables, and was performed in SAS 9.1.3. The discriminant function obtained an overall cross-validated classification rate of 86.69%. Females were classified correctly in 88.64% of the cases and males were correctly classified in 84.75% of the cases. Due to the increasing heterogeneity of current populations further discussion on this topic will include the importance that the re-evaluation of past studies has on modern forensic populations. Due to secular and micro evolutionary changes among populations, the near future must include additional methods being updated, and new methods being examined, both which should cover a wide population spectrum.     

Application of Kvaal et al.'s age estimation method to panoramic radiographs from Turkish individuals

Age estimation of living adult individuals can be accomplished with limited methods. Radiographic dental methods based on the pulpal narrowing with secondary dentin formation have been presented. In the present study, Kvaal et al.'s method, one of the radiographic dental age estimation methods, was applied to panoramic radiographs from Turkish individuals. The correlation between chronological and estimated ages was examined and the feasibility of length and width measurements of pulp cavity was evaluated for age estimation. The study population consisted of 123 patients with ages ranging from 14 to 57 years. The measurements of the length and width of six types of teeth on digitized panoramic radiographs were performed, and the ratios between tooth and pulp cavity measurements were calculated. Age was estimated using the linear regression models presented by Kvaal et al. and Paewinsky et al. High differences were observed between chronological and estimated ages. Measurement ratios showed no significant or weak correlation with age. The linear regression models were derived using variables that were significantly correlated with age. The determination coefficients of the models varied from 0.035 to 0.345. In conclusion, a difference of more than 12 years in the chronological and estimated ages derived using regression models in literature was found on panoramic radiographs in Turkish individuals. The length and width of the pulp cavity, measured according to the method of Kvaal et al. using panoramic radiographs, were insufficient to precisely estimate the age of Turkish individuals.     

Long Bone (Humerus,Femur, Tibia) Measuring Procedure in Cadavers

In this work, we present a measuring methodology for long bones of the limbs (humerus, femur, and tibia) of human corpses. Measurements of cadaveric height and long bone lengths were conducted on 72 corpses (20 females and 52 males) from the School of Medicine at the National Autonomous University of Mexico. Additionally, these measurements were compared with those taken from dry bones of a subsample of individuals. Our results show marginal differences (TEM% = 0.59) between cadaveric and dry bone measurements, resulting from different osteometric technical procedures. This note outlines the measuring methodology, which will be subsequently used to create regression formulas for stature estimation.     

Stature estimation from fragmentary femora: a revision of the Steele method

The skeletal remains presented to forensic anthropologists are often fragmentary. Previously described methods of estimating stature from segments of long bones have not proved satisfactory because of the difficulty involved in identifying the precise anatomical landmarks by which they are defined. This study represents an assessment of the feasibility of stature estimation from fragmentary femora. A sample of 200 males and females, blacks and whites (total sample = 800), was obtained from the Terry Collection. New regression equations for the estimation of maximum femur length and stature from three well-defined and easy-to-measure segments of the femur are presented. This technique represents an improvement over methods currently in use for estimating stature from femur fragments; the location of the anatomical landmarks and the accuracy of the prediction are enhanced. The applicability of these formulae to a modern forensic sample is addressed with regard to secular trends in stature increase and changes in body segment proportions.     

Estimation of stature in children from radiographically determined metacarpal length

Whether radiographically determined second metacarpal diaphyseal length could provide a reliable estimator of stature in children was investigated. The data consist of measurements of stature and 1597 left hand-wrist radiographs of children from 1 to 7 years of age from rural Guatemala. The errors in estimating stature in children from metacarpal length are comparable to those from equations estimating stature from long bones. It is concluded that second metacarpal length may be a reliable and practicable referent for the estimation of stature in children.     

On the applicability of secondary dentin formation to radiological age estimation in young adults

The literature provides linear regression formulas for dental age estimation that is based on radiological two-dimensional measurements of the pulp size. The aim of the present study was to explore whether the previously presented regression formulas could lead to statistically sound results and to appropriate repeatability when applied to young individuals. Orthopantomograms (OPGs) of 44 Austrian individuals, aged between 13 and 24 years, were selected at random. In accordance with the reported method, six teeth on each OPG were chosen to carry out the measurements. Statistical analysis was performed in order to assess the difference between the estimated and the true chronological age. The regression formulas reported by Kvaal et al. (1995) led to a consistent underestimation; the regression formulas reported by Paewinsky et al. (2005) resulted in a constant overestimation of age. The statistical analysis of intraobserver and interobserver variation revealed a variation width below 2%, respectively.     

Mandibular morphology as an indicator of human subadult age: interlandmark approaches

The dentition is widely recognized as the set of developmental markers that appear to show the least variability against chronological age; these markers are thus widely used in forensic anthropological investigations. As a possible alternative, we investigate here the potential of mandibular morphology as a developmental marker for estimating age at death in subadults. The sample analyzed comprises 79 known age and sex subadult individuals of South African Bantu and African American origin. Linear measurements of ramus height were obtained from the mathematical conversion of three-dimensional landmark data. A series of regression analyses were then performed to predict age by using the measurement of ramus height; results were cross-validated using a jackknife procedure. Our results show that ramus height can be used to predict age in the subadult skeleton with accuracy, closely approaching that of standards based on the dentition (standard error rates are between +/-1.1 years and +/-2.4 years).     

Gestational age discrepancies due to acquisition artifact in the forensic fetal osteology collection at the National Museum of Natural History, Smithsonian Institution, USA

Previously, numerous techniques have been used to assess either lunar or gestational age from fetal remains, such as from the external dimensions of the fetus, presence or absence of external features and ossification centers. One of the largest fetal collections in the U.S. is assessed with regard to errors in its biologic profile (ancestry, sex and age), the nature of the collection process, the methods of collection and the subsequent considerations for usage. Hrdlicka recorded the age, ancestry, sex and external measurements on card catalogs in the early 1900s for future use. For the purpose of this pilot study, measurements on 38 suitable fetuses stored at NMNH were used to calculate lunar age and compare with the recorded age in the card catalog. The differences between the age assessments are as follows: 20 showed no difference, 11 were discrepant by one month, 6 varied by 2 months and 1 diverged by 5 months. The average difference between lunar ages is 0.74 months, reflecting a nearly three-week difference. The purpose of this paper is to demonstrate that such discrepancies exist and to confirm specimens with accurate ages, which can be marked for future research. Moreover, it is also the purpose of this paper to demonstrate that such bias artifact exists in museum collections, and that this artifact needs to be eliminated from the sample materials prior to study.     

Estimation of fetal age from dimensions of atlas and axis ossification centers

The atlas and axis ossification centers of 106 human fetal and neonate skeletons were measured. The skeletons belong to the collection in the Department of Forensic Medicine of the Albert Szent-Gy?rgyi Medical University, Szeged, Hungary. The age of the skeletons ranged from 4 to 10 lunar months. Nine linear measurements on the atlas, seven on the axis neural arches ossification centers and three on each one of the axis centra ossification centers were taken. We did simple and multiple linear regression analysis to estimate the age of fetuses. The results show that it is possible to use regression equations to estimate the fetal body length and age from atlas and axis ossification centers measurements during the whole period of development studied. The study of size and shape of the ossification centers using factorial analysis (principal component analysis) shows that the shape of the dens of the axis might be useful to estimate fetal viability.     

Postnatal ontogenesis of the tibia. Implications for age and sex estimation

The growth of five variables of the tibia (diaphyseal length, diaphyseal length plus distal epiphysis, condylo-malleolar length, sagittal diameter of the proximal epiphysis, maximum breadth of the distal epiphysis) were analysed using polynomial regression in order to evaluate their significance and capacity for age and sex determination during and after growth. Data were collected from 181 (90♂ and 91♀) individuals ranging from birth to 25 years of age and belonging to three documented collections from Western Europe. Results indicate that all five variables exhibit linear behaviour during growth, which can be expressed by a first-degree polynomial function. Sexual significant differences were observed from age 15 onward in the two epiphysis measurements and condylo-malleolar length, suggesting that these three variables could be useful for sex determination in individuals older than 15 years. Strong correlation coefficients were identified between the five tibial variables and age. These results indicate that any of the studied tibial measurements is likely to serve as a useful source for estimating sub-adult age in both archaeological and forensic samples.