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Sex determination from the femur in Portuguese populations with classical and machine-learning classifiers

Publication . Curate, Francisco; Umbelino, Cláudia; Perinha, A.; Nogueira, C.; Silva, A. M.; Cunha, E.

The assessment of sex is of paramount importance in the establishment of the biological profile of a skeletal individual. Femoral relevance for sex estimation is indisputable, particularly when other exceedingly dimorphic skeletal regions are missing. As such, this study intended to generate population-specific osteometric models for the estimation of sex with the femur and to compare the accuracy of the models obtained through classical and machine-learning classifiers. A set of 15 standard femoral measurements was acquired in a training sample (100 females; 100 males) from the Coimbra Identified Skeletal Collection (University of Coimbra, Portugal) and models for sex classification were produced with logistic regression (LR), linear discriminant analysis (LDA), support vector machines (SVM), and reduce error pruning trees (REPTree). Under cross-validation, univariable sectioning points generated with REPTree correctly estimated sex in 60.0e87.5% of cases (systematic error ranging from 0.0 to 37.0%), while multivariable models correctly classified sex in 84.0-92.5% of cases (bias from 0.0 to 7.0%). All models were assessed in a holdout sample (24 females; 34 males) from the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal), with an allocation accuracy ranging from 56.9 to 86.2% (bias from 4.4 to 67.0%) in the univariable models, and from 84.5 to 89.7% (bias from 3.7 to 23.3%) in the multivariable models. This study makes available a detailed description of sexual dimorphism in femoral linear dimensions in two Portuguese identified skeletal samples, emphasizing the relevance of the femur for the estimation of sex in skeletal remains in diverse conditions of completeness and preservation. (C) 2017 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

2017-11Journal article

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Pediatric chronic osteomyelitis in the outskirts of Al-Ushbuna (Carnide, Lisboa, Portugal)

Publication . Tavares, Ana; Makhoul, Calil; Monteiro, Mario; Curate, Francisco

The skeletal remains of seven individuals (five non-adults and two adults) were recovered during an archeological intervention in the township of Carnide (Lisbon, Portugal). Funerary anthropology strongly suggests that the sample is from the Medieval Islamic period (8th -12th centuries AD). This report presents a case of chronic osteomyelitis in a non-adult individual. The diagnostic is substantiated by the presence of pathognomonic signs of osteomyelitis, including the presence of cloacae and a sequestrum in the left tibia. The bone infection is discussed in the context of inadequate socioeconomic conditions. This case from a relatively unfamiliar chronology and cultural context supplements the uncommon paleopathological descriptions of osteomyelitis in non-adults from historical populations.

2017-09Journal article

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A method for sex estimation using the proximal femur

Publication . Curate, Francisco; Coelho, João; Gonçalves, David; Coelho, Catarina; Ferreira, Maria Teresa; Navega, David; Cunha, Eugénia

The assessment of sex is crucial to the establishment of a biological profile of an unidentified skeletal individual. The best methods currently available for the sexual diagnosis of human skeletal remains generally rely on the presence of well-preserved pelvic bones, which is not always the case. Postcranial elements, including the femur, have been used to accurately estimate sex in skeletal remains from forensic and bioarcheological settings. In this study, we present an approach to estimate sex using two measurements (femoral neck width [FNW] and femoral neck axis length [FNAL]) of the proximal femur. FNW and FNAL were obtained in a training sample (114 females and 138 males) from the Luis Lopes Collection (National History Museum of Lisbon). Logistic regression and the C4.5 algorithm were used to develop models to predict sex in unknown individuals. Proposed cross-validated models correctly predicted sex in 82.5-85.7% of the cases. The models were also evaluated in a test sample (96 females and 96 males) from the Coimbra Identified Skeletal Collection (University of Coimbra), resulting in a sex allocation accuracy of 80.1-86.2%. This study supports the relative value of the proximal femur to estimate sex in skeletal remains, especially when other exceedingly dimorphic skeletal elements are not accessible for analysis. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

2016-09Journal article

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Femoral cortical bone in a Portuguese reference skeletal collection

Publication . Curate, Francisco; Cunha, Eugenia

This study aims to investigate patterns of femoral cortical bone fragility with age (at death) and to evaluate its associations with sex and bone mineral density. Radiogrammetric parameters of the femur and bone mineral density at the proximal femur were assessed in an adult sample (N=98) from the Coimbra Identified Skeletal Collection (Portugal). Diaphysis total width (DTW), femoral cortical index (FEMCI) and bone mineral density (BMD) are significantly higher in males, while medullary width (MW) is not statistically different between sexes. Cortical bone parameters of the femoral diaphysis are associated with age only in women, whereas BMD decreases with age in both sexes. The evaluation of femoral cortical bone reveals sex-specific trajectories of endosteal bone loss and periosteal apposition, stemming from sexual differences in the rate and pattern of bone loss, and in bone size. In females, endocortical bone loss rises with age, particularly in peri- and postmenopausal years, decelerating later in life. Concomitantly, accretion of bone in the subperiosteal surface persists throughout adulthood - partially offsetting bone fragility in women. Strength in the femoral mid diaphysis appears to be pre served throughout most of the life course in both sexes.

2017Journal article

Open Access

A method for estimating gestational age of fetal remains based on long bone lengths

Publication . Carneiro, Cristiana; Curate, Francisco; Cunha, Eugénia

The estimation of gestational age (GA) in fetal human remains is important in forensic settings, particularly to assess fetal viability, in addition to often being the only biological profile parameter that can be assessed with some accuracy for non-adults. The length of long bone diaphysis is one of the most frequently used methods for fetal age estimation. The main objective of this study was to present a simple and objective method for estimating GA based on the measurements of the diaphysis of the femur, tibia, fibula, humerus, ulna, and radius. Conventional least squares regression equations (classical and inverse calibration approaches) and quick reference tables were generated. A supplementary objective was to compare the performance of the new formulae against previously published models. The sample comprised 257 fetuses (136 females and 121 males) with known GA (between 12 and 40 weeks) and was selected based on clinical and pathological information. All measurements were performed on radiographic images acquired in anonymous clinical autopsy records from spontaneous and therapeutic abortions in two Portuguese hospitals. The proposed technique is straightforward and reproducible. The models for the GA estimation are exceedingly accurate and unbiased. Comparisons between inverse and classical calibration show that both perform exceptionally well, with high accuracy and low bias. Also, the newly developed equations generally outperform earlier methods of GA estimation in forensic contexts. Quick reference tables for each long bone are now available. The obtained models for the estimation of gestational age are of great applicability in forensic contexts.

2016-09Journal article

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