Estimación del sexo con metacarpos y metatarsos para población mexicana / Estimation of gender from metacarpals and metatarsals in a Mexican population

INTRODUCCIÓN: El objetivo de este estudio fue la obtención de funciones discriminantes para estimación del sexo a partir de mediciones directas en metacarpos y metatarsos para contribuir en la identificación de individuos desconocidos. MATERIAL Y MÉTODOS: Se analizaron métricamente los metacarpos y metatarsos de 112 esqueletos adultos contemporáneos (49 femeninos y 63 masculinos) de la Colección-UNAM del Laboratorio de Antropología Física, Facultad de Medicina, UNAM. Empleando un vernier digital se tomaron 5 medidas (longitud máxima y 4 anchuras) en cada uno de los huesos del metacarpo y del metatarso. RESULTADOS: Se desarrollaron 14 funciones discriminantes para los metacarpos, con porcentajes del 79,5% a 85,3% de asignación sexual correcta, siendo el segundo metacarpo el hueso más dimórfico de la muestra. Para el caso de los metatarsos se obtuvieron 5 funciones que van del 77,8% al 83,2% de certidumbre, siendo el primer metatarso el hueso más dimórfico. De manera general, las anchuras en ambas epífisis fueron las medidas más dimórficas. CONCLUSIONES: Las funciones discriminantes de metacarpos y metatarsos obtenidas presentan, de manera general, porcentajes por encima del 80%, lo cual concuerda con lo reportado para otras poblaciones; por lo tanto, pueden ser utilizadas en contextos forenses para la identificación humana, en restos completos o fragmentados, en el caso de no contar con otro elemento óseo, como la pelvis

INTRODUCTION: The aim of this study was to obtain discriminant functions for estimating gender from direct measurements of the metacarpal and metatarsal bones for identification of unknown individuals. MATERIAL AND METHODS: An analysis was performed on metacarpal and metatarsals bones of 112 adult contemporary skeletons (49 females and 63 males). The sample belongs to the Autonomous University of Mexico (UNAM) Collection from the Physical Anthropology Laboratory, UNAM Faculty of Medicine. Five measurements were taken (maximum length and four widths) of each metacarpal and metatarsal bones employing a digital calliper. RESULTS: Fourteen discriminant functions were developed for metacarpals with percentages from 79.5% to 85.3% of correct gender classification. The second metacarpal was the most dimorphic of the sample. For metatarsals, five discriminant functions were obtained, ranging from 77.8% to 83.2% of certainty. In this case the first metatarsal was the most dimorphic. In general terms, the widths of both epiphyses were the most dimorphic measurements. CONCLUSIONS: The discriminant functions of metacarpal and metatarsal bones obtained are generally above 80%, which is similar to reports from other populations. Therefore, it can be used in forensic contexts for human identification with complete or fragmented remains, in the cases where no other bone element is available, such as the pelvis

Anatomía morfométrica de importancia clínica del atlas en relación a la estabilización del complejo atlantoaxial y occipitocervical / Morphometric anatomy of clinical importance of the atlas in relation to the stabilization of the atlantoaxial and occipitocervical complex

RESUMEN: Evaluar de manera integral los parámetros morfométricos de la vértebra atlas (C1) en la población mexicana de relevancia en la realización de procedimientos quirúrgicos de la unión craneocervical con el fin de proveer datos cuantitativos indispensables para su realización. Para este estudio se utilizaron un total de 576 vértebras C1 secas de población mexicana contemporánea. Se realizaron 11 mediciones respecto a la morfología de C1. Las mediciones se efectuaron bilateralmente utilizando un vernier digital milimétrico con una precisión de 0,01 milímetros y se aplicó un análisis estadístico. Un total de 576 vértebras atlas (C1), fueron medidas de manera bilateral, todas nuestras mediciones se reportaron en milímetros. El promedio del ancho de las masas lateral fue de 14,87 mm ± 1,38 mm. El promedio de la altura de las masas laterales fue de 4,05 mm ± 0,93 mm. El promedio del ancho del foramen transverso fue de 5,93 mm ± 0,98 mm. El promedio del largo del foramen transverso fue de 6,96 mm ± 0,98 mm. El promedio de la altura del foramen transverso fue de 5,76 mm ± 1,31 mm. El promedio del ancho del surco de la arteria vertebral fue de 18,87 mm ± 1,3 mm. El promedio de la distancia entre la línea media y el margen medial del surco de la arteria vertebral sobre la superficie anterior del arco posterior de C1 en su cara superior fue de 12,47 mm ± 3,14 mm. El promedio de la distancia entre la línea media y el margen medial del surco de la arteria vertebral sobre la superficie posterior del arco posterior de C1 en su cara superior fue de 18,75 mm ± 3,94 mm. El promedio de la distancia entre la línea media y el margen lateral del surco de la arteria vertebral sobre la superficie anterior del arco posterior de C1 en su cara superior fue de 19,7 mm ± 2,52 mm. El promedio de la distancia entre la línea media y el margen lateral del surco de la arteria vertebral sobre la superficie posterior del arco posterior de C1 en su cara superior fue de 29,52 mm ± 3,23. Nuestro estudio demuestra que las mediciones realizadas en nuestra población presentan diferencias significativas respecto a lo reportado actualmente en la literatura. Es necesario contar con un conocimiento de la morfología vertebral en nuestra población para disminuir la ventana de error al realizar procedimientos quirúrgicos que involucren este segmento.

SUMMARY: To evaluate in an integral way the morphometric parameters of the atlas (C1) vertebra in the Mexican population of relevance in performing surgical procedures of the craniocervical junction in order to provide quantitative and essential data for its realization. For this study, a total of 576 dry C1 vertebrae of contemporary Mexican population were used. Eleven measurements were carried out regarding the morphology of C1. The measurements were made bilaterally using a millimeter digital vernier with an accuracy of 0.01 millimeters and a statistical analysis was applied. A total of 576 atlas vertebrae (C1) were measured bilaterally, all our measurements were reported in millimeters. The average width of the lateral masses was 14.87 mm ± 1.38 mm. The average height of the lateral masses was 4.05 mm ± 0.93 mm. The average width of the transverse foramen was 5.93 mm ± 0.98 mm. The average length of the transverse foramen was 6.96 mm ± 0.98 mm. The average height of the transverse foramen was 5.76 mm ± 1.31 mm. The average width of the groove of the vertebral artery was 18.87 mm ± 1.3 mm. The average distance between the midline and the medial edge of the vertebral artery groove on the anterior surface of the posterior arch of C1 on its superior surface was 12.47 mm ± 3.14 mm. The average distance between the midline and the medial border of the vertebral artery groove on the posterior surface of the posterior arch of C1 on its upper face was 18.75 mm ± 3.94 mm. The average distance between the midline and the lateral border of the vertebral artery groove on the anterior surface of the posterior arch of C1 on its superior surface was 19.7 mm ± 2.52 mm. The average distance between the midline and the lateral border of the vertebral artery groove on the posterior surface of the posterior arch of C1 on its superior surface was 29.52 mm ± 3.23. Our study shows that the measurements made in our population present differences with respect to what is currently reported in the literature. It is necessary to have knowledge of vertebral morphology in our population to reduce the error window when performing surgical procedures involving this segment.

Variations in the Torg-Pavlov cervical ratio with regard to age and sex: a comprehensive anatomical and morphometric study on contemporary cadaveric specimens / Variaciones en el índice de Torg-Pavlov cervical respecto a edad y sexo: un exhaustivo estudio anatómico en una población contemporánea

The Torg-Pavlov ratio is a method used to detect cervical stenosis. A Torg-Pavlov ratio ≤0.80 suggests significant stenosis. This ratio is obtained by dividing the anteroposterior diameter of the cervical canal by the anteroposterior diameter of the vertebral body. The aim of this study was to evaluate these parameters and determine if there are significant differences with respect to sex and age. This is an anatomical and comparative study in which 1020 cervical vertebrae from C2-C7 from an osteological collection were evaluated. We determined the anteroposterior diameter from the vertebral body, the anteroposterior diameter from the vertebral canal and the Torg-Pavlov ratio. The pieces studied were divided into groups according to sex and age, resulting in six groups of study. A statistical analysis was made to determine the significance of the differences between sex and age groups. The size of the vertebral body diminished form C2-C3 and increased from C4-C7. The canal diminished form C2-C4 and increased from C5-C7. The Torg-Pavlov ratio decreased from C2-C7. The body and the canal were higher in men, while the Torg-Pavlov ratio was higher in women. With age, in men, the size of the body increased, the canal maintained its size, and the Torg-Pavlov ratio diminished significantly. In the group of women ≥60 years, the size of the body decreased, and the canal and the Torg-Pavlov ratio increased. In men, the Torg-Pavlov ratio is determined by the vertebral body and canal, because these did not show differences in most of the age groups. While in women, it is determined mostly by the spinal canal because it presented more variability between the age groups.

El Índice de Torg-Pavlov se utiliza para la detección de estenosis del canal cervical. Un resultado ≤0.80 indica estenosis significativa. Se obtiene dividiendo el diámetro anteroposterior del canal cervical entre el diámetro anteroposterior del cuerpo. El objetivo de este estudio fue evaluar estos parámetros y determinar si existen diferencias significativas en relación con el sexo y la edad. Se realizó un estudio anatómico y comparativo, en el que se incluyeron 1020 vértebras cervicales de C2-C7 tomadas de una colección osteológica. Se determinó el diámetro anteroposterior del cuerpo vertebral, el diámetro anteroposterior del canal vertebral y el Índice de Torg-Pavlov. Las piezas evaluadas se dividieron en grupos de acuerdo al sexo y la edad, resultando en seis grupos de estudio. Se realizó un análisis estadístico para determinar si existían diferencias significativas entre estos grupos. El tamaño del cuerpo vertebral disminuyó de C2-C3 y aumentó de C4-C7. El canal disminuyó de C2-C4 y aumentó de C5-C7. El Índice de Torg-Pavlov disminuyó de C2-C7. El cuerpo y el canal vertebral fueron mayores en los hombres, mientras que el Índice de Torg-Pavlov fue mayor en las mujeres. Con la edad, en los hombres, el tamaño del cuerpo vertebral aumentó, el canal mantuvo su tamaño y el Índice de Torg-Pavlov disminuyo significativamente. En el grupo de mujeres ≥60 años, el tamaño del cuerpo disminuyó y el canal y el Índice de Torg-Pavlov aumentaron. En los hombres, el tamaño del cuerpo y el canal vertebral determinan el Índice de Torg-Pavlov, ya que estos no mostraron diferencias en la mayoría de los grupos de edad. Mientras que, en las mujeres, este está determinado principalmente, por el canal vertebral, porque este parámetro presento más variabilidad entre los grupos de edad.

Sex and age morphometric variations in bony nasolacrimal duct and fossa for lacrimal gland in Mexican population / Variaciones morfométricas de sexo y edad en el conducto nasolagrimal óseo y la fosa de la glándula lagrimal en la población mexicana

Primary acquired nasolacrimal duct obstruction is greater in women over 40 years and has been associated with morphometric variations in the osseous nasolacrimal duct, which varies according to age and sex. The objective is to determine variations regarding sex and age of the nasolacrimal duct and osseous fossa for lacrimal gland. One hundred sixteen dry orbits from Mexican population were analyzed; subdivided into four groups based on age and sex. The length, transverse and anteroposterior diameters of the bone entrance of the nasolacrimal duct, and the length and width of the fossa for lacrimal gland were determined. Statistical tests were applied to determine the significance of the differences found between groups. The nasolacrimal duct in women had shorter length than men in both age groups. The entrance had a wider transverse diameter in women than men independently of age and its anteroposterior diameter was shorter in men under 40 years than over 40 years. The fossa for lacrimal gland was larger in women under 40 years than in men of same age group and women over 40 years old. The lower third of the was wider in women under 40 years than in women over 40 years. Our study confirms significant differences between sex and age groups in some of the morphometric measurements of bony nasolacrimal duct and fossa for lacrimal gland in Mexican population. Comparative studies with and without clinical illness are needed to clarify if the bony characteristics of those structures participate in the etiopathogenesis and distribution differences observed in sex, age and ethnicity of thisillness.

La obstrucción de la vía lagrimal inferior es mayor en mujeres mayores de 50 años y se ha asociado a variaciones morfométricas en la entrada ósea del conducto nasolagrimal (CNL), las cuales varían según edad y sexo. El objetivo del presente estudio es determinar las variaciones respecto a sexo y edad de los diámetros de la entrada ósea del CNL, longitud del CNL y fosa de la glángula lagrimal (FL) ósea. Se analizaron 116 órbitas secas de población mexicana, los cuales a su vez fueron subdivididos en dos subgrupos en base a la edad y sexo. Se determinaron los diámetros transverso y anteroposterior de la entrada ósea del CNL, la longitud del CNL y la longitud y anchura de la FL. Se aplicaron pruebas estadísticas para determinar la significancia de las diferencias entre los grupos de estudio. La longitud del CNL fue menor en mujeres que en hombres en ambos grupos de edad. En cuanto a la entrada ósea del CNL, el diámetro transverso de fue significativamente menor en hombres que en mujeres independientemente de la edad y el diámetro anteroposterior fue menor en hombres < 40 que en > 40. La longitud de la FL fue mayor en mujeres < 40 años que en hombres del mismo rango de edad y que en mujeres > 40 años. La anchura de la FL en el tercio inferior fue menor en mujeres > 40 años que < 40 años. El resto de las mediciones de la FL no presentó diferencias significativas por sexo ni grupo de edad. Nuestro estudio confirmó que existen diferencias entre sexo y grupo de edad en algunas mediciones morfométricas del CNL y FL óseas en población mexicana. Se necesitan estudios comparativos entre personas con y sin obstrucción clínica de vía lagrimal inferior para esclarecer si las características óseas de estas estructuras participan o no en la etiopatogenia y las diferencias de distribución en género, edad y etnia de esta enfermedad.

Stature estimation formulae for Mexican contemporary population: A sample based study of long bones.

Stature estimation is an important step to create a biological profile for human identification of unknown individuals in forensic anthropological practice, and it is well known that the long bone length is highly correlated with this feature. The purpose of the present study is to develop formulae for height estimation, based on simple linear regression model for humerus, femur and tibia in Mexican contemporary population. Stature was taken in 56 males and 30 female corpses as well as maximum length of three long bones of the limbs after autopsy following the Menéndez et al. (2014) criteria, at the Facultad de Medicina (School of Medicine) of the Universidad Nacional Autónoma de México. Based on this data, equations for each sex and for the three long bones were developed, obtaining a highly significant (p < .001) linear regression models with correlation coefficients of r = 0.820 for female femur and r = 0.855 for male tibia. In this manner, the new formulae provide better and reliable results of stature estimation for the contemporary population of Mexico.

Análisis de funciones discriminantes para la estimación del sexo con la mandíbula en población mexicana / Gender assessment using the mandible in the mexican population

Introducción. El presente trabajo tuvo como objetivos: conocer el grado de dimorfismo sexual entre una población de la Ciudad de México y otra de Hidalgo, México; y el desarrollo de funciones discriminantes para la estimación de sexo por medio de la mandíbula, para identificación humana. Material y métodos. Se analizaron morfométricamente mandíbulas de dos muestras, una procedente de la Ciudad de México (MEX) (Colección-UNAM) y otra de Santa María Xigui, Alfajayucan, Hidalgo, México (XIG). La muestra MEX consistió en 108 mandíbulas (75 masculinos y 33 femeninos) y en la muestra XIG se utilizaron 56 mandíbulas (33 femeninos y 30 masculinos), con una edad media entre 49,2 y 55,1 años. Se tomaron 18 medidas mandibulares y se desarrollaron cuatro funciones discriminantes para estimar el sexo con cada muestra. Resultados. Se observó el mismo patrón de diferenciación en ambas poblaciones, no obstante se presentaron diferencias entre estas, ya que se demostró que existe mayor grado de diferencias sexuales en XIG. Las funciones discriminantes desarrolladas para ambas poblaciones, alcanzaron entre el 76,4 y 84% de clasificación sexual correcta. Conclusiones. La muestra XIG presentó mayor dimorfismo sexual que la muestra MEX, con mandíbulas más alargadas y mentones altos y alargados. Las funciones discriminantes del presente trabajo presentan porcentajes de clasificación mayores a los de las demás propuestas existentes. Y al ser desarrolladas a partir de población contemporánea, pueden ser utilizadas en contextos forenses para identificación humana con restos completos o fragmentados y/o incompletos (AU)

Introduction. The aims of the present study were to determine the level of sexual dimorphism among two populations, one from Mexico City and the other from Hidalgo, Mexico, as well as the development of discriminant functions for gender assessment using the mandible, for human identification. Material and methods. Two samples of mandibles were analysed morphometrically, one from Mexico City (Colección-UNAM) (MEX), and the other from Santa María Xigui, Alfajayucan, Hidalgo, México (XIG). The sample MEX consisted of 108 mandibles (75 male and 33 female), and XIG sample with 56 mandibles (33 female and 30 male), with a mean age between 49.2 to 55.1 years old. Eighteen measurements were taken to create four discriminant functions for gender estimation for each sample. Results. The differentiation pattern among populations (samples) was the same. Nevertheless, there were differences between them, with a higher degree of sexual difference in XIG. The discriminant functions, developed for both populations, achieved a correct classification in between 76.4 and 84%, respectively. Conclusions. The XIG sample showed greater sexual dimorphism than the MEX sample, with longer mandibles and higher and elongated chins. The discriminant functions generated in this study, present higher classification percentages than the other existing proposals. Furthermore, being developed from the contemporary population, they can be used in forensic contexts for human identification, with complete or fragmented/incomplete remains (AU)

Recalibration of the Klales et al. (2012) method of sexing the human innominate for Mexican populations.

OBJECTIVES: The aim of this study was to test the accuracy of the Klales et al. (2012) equation for sex estimation in contemporary Mexican population. MATERIALS AND METHODS: Our investigation was carried out on a sample of 203 left innominates of identified adult skeletons from the UNAM-Collection and the Santa María Xigui Cemetery, in Central Mexico. The Klales' original equation produces a sex bias in sex estimation against males (86-92% accuracy versus 100% accuracy in females). Based on these results, the Klales et al. (2012) method was recalibrated for a new cutt-of-point for sex estimation in contemporary Mexican populations. RESULTS AND DISCUSSION: The results show cross-validated classification accuracy rates as high as 100% after recalibrating the original logistic regression equation. Recalibration improved classification accuracy and eliminated sex bias. This new formula will improve sex estimation for Mexican contemporary populations.

Shifts in subsistence type and its impact on the human skull's morphological integration.

OBJECTIVE: Here we evaluate morphological integration patterns and magnitudes in different skull regions to detect if shifts in morphological integration are correlated to the appearance of more processed (softer) diets. METHODS: To do so, three transitional populations were analyzed, including samples from groups that inhabited the same geographical region and for which the evidence shows that major changes occurred in their subsistence mode. Ninety three-dimensional landmarks were digitized on 357 skulls and used as the raw data to develop geometric morphometric analyses. The landmark coordinates were divided into several different regions of biomechanical interest, following a three-level hierarchically nested scheme: the whole skull, further subdivided into neurocranium (divided into the vault and basicranium), the facial (divided into the lower and upper facial), and the masticatory apparatus (divided into alveolar, temporal, and temporo-mandibular joint). RESULTS: Our results indicate that the morphological integration and variability patterns significantly vary across skull regions but are maintained across the transitions. The alveolar border and the lower facial are the regions manifesting greater value of morphological integration and variability, while the upper facial, the temporo-mandibular joint, and the basicranium are highly integrated and poorly variable. CONCLUSIONS: The transition to softer diets increased morphological variation across cranial regions that are more exposed to masticatory strains effects.

Clinical and surgical implications regarding morphometric variations of the medial wall of the orbit in relation to age and gender.

The ethmoidal foramens are located on the medial wall of the orbit and are key reference points for intraoperative orientation. Detailed knowledge of the anatomy, bony landmarks and morphometric characteristics of the medial wall of the orbit is essential for various surgical procedures. The aim of this study was to determine the morphometric variations in the medial wall of the orbit and establish significant variations regarding age and gender. A total of 110 orbits were analyzed and subdivided by age (over or under 40 years) and gender. The distances of the medial wall of the orbit between the anterior lacrimal crest, the ethmoidal foramen, the optic canal and the interforamina were determined. Safe surgical areas were sought. Statistical tests were used to determine the differences between groups. In men, there is a safe surgical area proximal to the anterior and posterior ethmoidal foramen. In women, this area is in the posterior third of the medial wall of the orbit between the posterior ethmoidal foramen and the optic canal. Regarding variation according to age, the results of this study suggested that the anteroposterior diameter of the medial wall increases with age. This study showed that the anteroposterior total length of the medial orbit wall is similar between genders of similar age, increases with age, and has significant variations in the distances between the various structures that make up the medial orbit wall with regard to gender and age.

A new morphological classification of the anterior inferior iliac spine: relevance in subspine hip impingement / Nueva clasificación morfológica de la espina iliaca anteroinferior: relevancia en el pinzamiento subespinoso de la cadera

Femoroacetabular impingement syndrome (FAI) is a clinical entity that has been recognized in recent years as a frequent cause of pain and the early development of hip arthrosis. Subspine hip impingement is characterized by the prominent or abnormal morphology of the anteroinferior iliac spine (AIIS), which contributes to the development of a clinical picture that is similar to FAI. The aims of this study were to propose a new morphological classification of the AIIS, to determine the prevalence of the different AIIS morphologies based on this classification and to correlate the presence of said morphologies with different gender and age groups. The sample consisted of 458 hemipelvises from individuals of known age and sex (264 men and 194 women). Each specimen was analyzed to determine the prevalence of each of the different morphologies of the AIIS based on the classification proposed as Type 1: the presence of a concave surface between the AIIS and the acetabular rim; Type 2A: the presence of a flat surface between the AIIS and the acetabular rim; Type 2B the presence of a convex surface between the AIIS and the acetabular rim; and Type 3: the AIIS protrudes inferiorly toward the anterior acetabulum. A prevalence of 69.87% was determined for Type 1 AIIS (320/458). In regard to abnormal morphology, prevalences of 17.90% (82/458), 3.71% (17/458) and 8.52% (39/458) were determined for type 2A, Type 2B and Type 3, respectively. The prevalence of abnormal AIIS morphology was 30.30% (80/264) in male specimens and 29.90% (58/194) in female specimens. This study demonstrates the prevalence of the different morphologies of the AIIS, providing information that will be useful in determining the role of the AIIS in the emergence of subspine hip impingement.

El Síndrome de Pinzamiento Femoroacetabular (PFA) es una entidad clínica reconocida en los últimos años como una causa de dolor y desarrollo de artrosis temprana de cadera. El pinzamiento subespinoso de la cadera se caracteriza por una espina iliaca anteroinferior (EIAI) prominente o con una morfología anormal, lo que contribuye al desarrollo de un cuadro clínico similar al PFA. El objetivo fue proponer una nueva clasificación morfológica de la EIAI y determinar las prevalencias de las distintas morfologías de la EIAI en base a la misma y correlacionarla con los distintos sexos y grupos de edad. La muestra consistió en un total de 458 hemipelvis, de sexo y edad conocidos (264 hombres y 194 mujeres). Cada pieza fue analizada para determinar la prevalencia de variaciones morfológicas de la EIAI en base a la clasificación propuesta. Tipo 1: presencia de una superficie cóncava entre la EIAI y reborde acetabular, Tipo 2A: presencia de una superficie plana entre la EIAI y el reborde acetabular, Tipo 2B: presencia de una superficie convexa entre la EIAI y el reborde acetabular y Tipo 3: la EIAI protruye hacia el acetábulo anterior o inferiormente. Se determinó una prevalencia de 69,87% para la EIAI Tipo 1 (320/458). En cuanto a las morfologías anormales, se determinó una prevalencia de 17,90% (82/458), 3,71% (17/458) y 8,52% (39/459) para los Tipos 2A, 2B y 3, respectivamente. La prevalencia de una morfología anormal en las EIAI de especímenes del sexo masculino fue de 30,30% (80/264) y en el sexo femenino 29,90% (58/194). Se evidencia la prevalencia de las diferentes morfologías que puede tener la EIAI; esta información será de ayuda para determinar el papel de la EIAI en la aparición del pinzamiento subespinoso de la cadera.

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.

Age- and gender-related variations in morphometric characteristics of thoracic spine pedicle: A study of 4,800 pedicles.

Transpedicular spinal fusion is the most commonly used fixation technique for the surgical treatment of vertebral disorders. However, the instrumentation of the thoracic spine using this technique continues to be controversial. The objective of the present study was to determine the morphometric characteristics of the thoracic pedicle and to establish how these characteristics vary with gender and age. Two hundred thoracic spines (4800 thoracic pedicles) from individuals of known gender and age were analyzed (in accordance with the order of vertebrae). The spines were divided into six groups according to age and gender. The horizontal and vertical diameters of the thoracic pedicle were determined for each piece. The mean and standard deviation of each variable were determined, and differences between age groups for each gender were evaluated using parametric correlation tests. The pedicle diameters of men and women differed significantly for most groups (P < 0.05). The horizontal diameters decreased from T1 to T5 and increased up to T12. The vertical diameter followed a cephalocaudal pattern of development from T1-T12. The pedicle diameters decreased with increasing age in women, while the opposite trend was observed in men. In men, the dimensions of the thoracic spine pedicle increase with increasing age; in women, they decrease. These differences should be taken into account when selecting the appropriate pedicle screw.

FGFR1 signaling is associated with the magnitude of morphological integration in human head shape.

OBJECTIVES: The head can be used as a model to study complex phenotypes controlled simultaneously by morphological integration (MI) due to common factors, and modular patterns caused by local factors affecting the development and functional demands of specific structures. The fibroblast growth factor and receptor system (FGF/FGFR) participates in cell communication and pattern formation in osseous tissues, among others, and there is compelling evidence from mouse model studies suggesting a role of the FGF/FGFR pathway as a covariance-generating signaling process in head development. Here we use human data to test if specific genetic variants of another gene of this pathway, the FGFR1 gene, can be associated with differences in the integration of the head. METHODS: We explored whether and how three specific variants on FGFR1, previously associated with human cephalic index, influence the pattern and level of head integration of one Native American and one admixed group from Mexico. MI, measured as the intensity of covariation among head traits, was assessed using data from three-dimensional head landmark coordinates taken on 176 individuals. RESULTS: Individuals carrying the derived allele of the rs4647905:G>C polymorphism present significantly greater levels of head MI, especially in facial structures and on the shape space where the modular portion of the covariation is explicitly removed. CONCLUSIONS: Since FGFR genes present nonconservative and tissue-specific splicing sites, they may have some effect on protein structure and performance likely involved in developmental processes responsible for the magnitude and pattern of MI in the human head.

Technical note: geometric morphometrics and sexual dimorphism of the greater sciatic notch in adults from two skeletal collections: the accuracy and reliability of sex classification.

The greater sciatic notch (GSN) is one of the most important and frequently used characteristics for determining the sex of skeletons, but objective assessment of this characteristic is not without its difficulties. We tested the robustness of GSN sex classification on the basis of geometric morphometrics (GM) and support vector machines (SVM), using two different population samples. Using photographs, the shape of the GSN in 229 samples from two assemblages (documented collections of a Euroamerican population from the Maxwell Museum, University of New Mexico, and a Hispanic population from Universidad Nacional Autónoma de México, Mexico City) was segmented automatically and evaluated using six curve representations. The optimal dimensionality for each representation was determined by finding the best sex classification. The classification accuracy of the six curve representations in our study was similar but the highest and concurrently homologous cross-validated accuracy of 92% was achieved for a pooled sample using Fourier coefficient and Legendre polynomial methods. The success rate of our classification was influenced by the number of semilandmarks or coefficients and was only slightly affected by GSN marginal point positions. The intrapopulation variability of the female GSN shape was significantly lower compared with the male variability, possibly as a consequence of the intense selection pressure associated with reproduction. Males were misclassified more often than females. Our results show that by using a suitable GSN curve representation, a GM approach, and SVM analysis, it is possible to obtain a robust separation between the sexes that is stable for a multipopulation sample.

Fibroblast growth factor receptor 1 (FGFR1) variants and craniofacial variation in Amerindians and related populations.

OBJECTIVES: The polymorphic site rs4647905 of the FGFR1 gene was previously associated with a decrease in cephalic index (CI). Here, we evaluate the relationships between genotypes and cephalometric measurements and indices in one Mexican Native and two mestizo Mexican populations using two haplotype-tag SNPs (rs4647905 and rs3213849) that represent >85% of the FGFR1 variability, plus three other SNPs (rs2293971, rs2304000, and rs930828) situated nearby. In addition, we genotyped five South American natives, two European, one African, and one Siberian populations to evaluate their intra and intercontinental population diversity. METHODS: The five SNPs were tested and the craniofacial measurements and indices were collected using standardized procedures. Principal Component Analysis was used to verify individual/population comparisons. Associations were performed through the generalized linear model (GLM), coefficient of determination R(2) and linear regression tests. RESULTS: We found a tendency for a decrease in CI in individuals homozygous for allele rs4647905C, regardless of the population to which they belong, though the effect is more pronounced in mestizo. When the GLM analyses were performed using the absolute/linear cephalometric measurements, a statistically significant association was found between four SNPs and head length in the mestizo population. CONCLUSIONS: FGFR1 polymorphisms, especially rs4647905, can have an important role in the normal human skull variation, primarily due to their influence in head length, which would affect other cephalometric absolute/linear measures as well as indices like CI as a result of the pervasive nature of the morphological integration that characterizes the human skull.

Comparison of methods to determine sex by evaluating the greater sciatic notch: Visual, angular and geometric morphometrics.

Sex estimation is the first step for biological profile reconstruction of an unknown skeleton (archaeological or contemporary) and consequently for positive identification of skeletal remains recovered from forensic settings. Several tools have been developed using different osseous structures. With the intention to provide an objective method comparison, we reported the analysis of three different methods (visual, metric and geometric morphometrics) for sex assessment of the greater sciatic notch. One hundred and thirty pelvic bones (45.4% females and 54.6% males) from the National Autonomous University of Mexico Skeletal Collection pertaining to the contemporary Mexican population were analyzed. We used the ROC-analysis to test between desired false positive thresholds (1-specificity) and expected true positive rates (sensitivity) in order to predict the best approach to sex assessment. The comparison of the area under the ROC-curves shows significant differences among visual and metric methods. At the same time, the analysis suggested that higher morphological variation among the sexes is independent of the methodological approach. The results indicate that the metric (angle), with a high percent of indeterminate cases (34.6%), and visual, with 26.2% of the cases allocated as intermediate cases, were poorly accurate; we cannot recommend these techniques for sexing an unknown specimen. On the other hand, the geometric morphometrics approach improves sex estimation in 82.3% of correctly classified individuals with more than 95% of posterior probability. In addition to the method comparison, the major sexual variation of the greater sciatic notch was determined to be located on its posterior border.

Sex assessment from carpals bones: discriminant function analysis in a contemporary Mexican sample.

Sex assessment is one of the first essential steps in human identification, in both medico-legal cases and bio-archaeological contexts. Fragmentary human remains compromised by different types of burial or physical insults may frustrate the use of the traditional sex estimation methods, such as the analysis of the skull and pelvis. Currently, the application of discriminant functions to sex unidentified skeletal remains is steadily increasing. However, several studies have demonstrated that, due to variation in size and patterns of sexual dimorphism, discriminant functions are population-specific. In this study, in order to improve sex assessment from skeletal remains and to establish population-specific discriminant functions, the diagnostic values of the carpal bones were considered. A sample of 136 individuals (78 males, 58 females) of known sex and age was analyzed. They belong to a contemporary identified collection from the Laboratory of Physical Anthropology, Faculty of Medicine, UNAM (Universidad Nacional Autónoma de México, Mexico City). The age of the individuals ranged between 25 and 85 years. Between four and nine measurements of each carpal bone were taken. Independent t-tests confirm that all carpals are sexually dimorphic. Univariate measurements produce accuracy levels that range from 61.8% to 90.8%. Classification accuracies ranged between 81.3% and 92.3% in the multivariate stepwise discriminant analysis. In addition, intra- and inter-observer error tests were performed. These indicated that replication of measurements was satisfactory for the same observer over time and between observers. These results suggest that carpal bones can be used for assessing sex in both forensic and bio-archaeological identification procedures and that bone dimensions are population specific.

Discriminant function analysis for sex assessment in pelvic girdle bones: sample from the contemporary Mexican population.

Sex assessment of skeletal remains plays an important role in forensic anthropology. The pelvic bones are the most studied part of the postcranial skeleton for the assessment of sex. It is evident that a population-specific approach improves rates of accuracy within the group. The present study proposes a discriminant function method for the sex assessment of skeletal remains from a contemporary Mexican population. A total of 146 adult human pelvic bones (61 females and 85 males) from the skeletal series pertaining to the National Autonomous University of Mexico were evaluated. Twenty-four direct metrical parameters of coxal and sacral bones were measured and subsequently, sides and sex differences were evaluated, applying a stepwise discriminant function analysis. Coxal and sacra functions achieved accuracies of 99% and 87%, respectively. These analyses follow a population-specific approach; nevertheless, we consider that our results are applicable to any other Hispanic samples for purposes of forensic human identification.