Sex estimation using computed tomography of the mandible.

Sex estimation of skeletal parts is of great value even in the DNA era. When computed tomography (CT) facilities were introduced to forensic institutes, new possibilities for sex estimation emerged. The aim of this study was to develop a CT-based method for sex estimation using the mandible. Twenty-five CT-based measurements of the mandible were developed and carried out on 3D reconstructions (volume rendering) and cross sections of the lower jaw of 438 adult individuals (214 males and 224 females). Intraobserver and interobserver variances of the measurements were examined using intraclass correlation coefficient (ICC) analysis. Five discriminant functions were developed using different states of completeness of the mandible. The success rates of these equations were cross validated twice. The measurements were found to be highly reliable (for intraobserver 0.838 < ICC < 0.995 and for interobserver 0.71 < ICC < 0.996). For a complete mandible, the correct classification rate was 90.8%. For incomplete mandibles, the correct classification rates varied from 72.9 to 85.6%. Cross-validation tests yielded similar success rates, for the complete mandible 89% and for the incomplete mandible 67.5 to 89%. We concluded that CT techniques are appropriate for estimating sex based on the mandible size and shape characteristics. Suggested discriminant functions for sex estimation are given with data on the correct classification rates.

The effect of impact tool geometry and soft material covering on long bone fracture patterns in children.

INTRODUCTION: The effect of impact tool geometry and soft material covering on bone fracture patterns plays a major role in fracture patterns. However, the literature is nearly void of such studies and only general correlations between the fracture pattern and the mechanism underlying the insult were reported. PURPOSE: The aim of this study is to reveal the association between the geometry of the impact tool and the presence of soft material covering on bone fracture patterns. The Dynatup Model POE 2000 (Instron Co.) low energy pendulum impact machine was utilized to apply impact loading on fresh pig femoral bones (n = 50). The bone clamp shaft was adjusted to position the bone for three-point bending with additional bone compression simulating a situation occurring in pedestrian road traffic accidents. Five different tests using varying impact tool sizes with and without soft interface covering were carried out. RESULTS: A significant positive correlation was found between the fracture features and the impact tool's geometry. Only bones that were damaged by a rounded impact body result in a "false" butterfly fragment; in all other cases where the impact body is flat and wide, double trapezoid fragments are observed in the area of impact. The impacted aspect is the most affected. All fracture line features were significantly greater in bones subjected to an impact by tools without soft covering. With an impact with soft covering, the impacted aspect exhibits numerous unique fracture lines and a fragmented pattern. Our study clearly shows that impact tool geometry and soft material covering markedly affect the fracture pattern.

The Associations between the Maxillary Sinus Volume, Infraorbital Ethmoid Cells, and the Infraorbital Canal: A CT-Based Study.

This CT-based study aimed to characterize and explain the existence of two anatomical structures positioned near the maxillary sinuses, which are of clinical relevance in rhinology and maxillofacial surgery. A total of 182 head scans (92 males and 90 females) were inspected for infraorbital ethmoid cells (IECs) and for the type (route) of infraorbital canal (IOC). The maxillary sinuses were segmented, and their volumes were measured. Statistical analysis was conducted to reveal the associations between the two anatomical variations, namely, sex and the maxillary sinus volume. Infraorbital ethmoid cells were noted in 43.9% of the individuals studied; they were more frequent in males (53.3%) than in females (34.4%). The descending infraorbital nerve (type 3 IOC) was found in 13.2% of individuals and was independent of sex. Infraorbital ethmoid cells were associated with the IOC types. The maxillary sinus volume was found to be sex-dependent. A large sinus volume is significantly associated with IOC Type 3 (the descending canal) and the presence of IEC. Dentists, radiologists, and surgeons should be aware that individuals with extensive pneumatization of the maxillary sinuses are more likely to display a descending IOC and IEC. These findings should be studied, along with CT scans, before treatment and surgery.

Hyperostosis frontalis interna: criteria for sexing and aging a skeleton.

Estimation of sex and age in skeletons is essential in anthropological and forensic medicine investigations. The aim of the current study was to examine the potential of hyperostosis frontalis interna (HFI) as a criterion for determining sex and age in forensic cases. Macroscopic examination of the inner aspect of the frontal bone of 768 skulls (326 males and 442 females) aged 1 to 103, which had undergone a head computerized tomography scan, was carried out using the volume rendering technique. HFI was divided into two categories: minor and major. HFI is a sex- and age-dependent phenomena, with females manifesting significantly higher prevalence than males (p<0.01). In both females and males, prevalence of HFI increases as age increases (p<0.01). We present herein the probabilities of designating an unknown skull to a specific sex and age cohort according to the presence of HFI (standardized to age distribution in an Israeli population). Moreover, we present the probability of an individual belonging to a specific sex or age cohort according to age or sex (respectively) and severity of HFI. We suggest a valid, reliable, and easy method for sex and age identification of unknown skulls.

3D virtual reconstruction and quantitative assessment of the human intervertebral disc's annulus fibrosus: a DTI tractography study.

The intervertebral disc's (IVD) annulus fibrosus (AF) retains the hydrostatic pressure of the nucleus pulposus (NP), controls the range of motion, and maintains the integrity of the motion segment. The microstructure of the AF is not yet fully understood and quantitative characterization is lacking, leaving a caveat in modern medicine's ability to prevent and treat disc failure (e.g., disc herniation). In this study, we show a reconstruction of the 3D microstructure of the fibers that constitute the AF via MRI diffusion tensor imaging (DTI) followed by fiber tracking. A quantitative analysis presents an anisotropic structure with significant architectural differences among the annuli along the width of the fibrous belt. These findings indicate that the outer annuli's construction reinforces the IVD while providing a sufficient degree of motion. Our findings also suggest an increased role of the outer annuli in IVD nourishment.

A morphological adaptation of the thoracic and lumbar vertebrae to lumbar hyperlordosis in young and adult females.

The lumbar shape in females is thought to be unique, compensating for lumbar hyperlordosis. Yet, the morphological adaptation of various vertebral parameters in the thoracic and lumbar spine to this unique posture in young and adult females has only been partially addressed in the literature. Our aim was to investigate the gender association to vertebral shape in the thoracic and lumbar spine as a possible adaptation to lumbar hyperlordosis in young and adult females. A three-dimensional digitizer was used to measure the vertebral body sagittal wedging, relative spinous process thickness, and relative interfacet width at the T1-L5 level. Two hundred and forty complete, non-pathological skeletons of adults and 32 skeletons of young individuals were assessed. Three major results were found to be independent of age and ethnicity: (a) VB sagittal wedging in females was significantly less kyphotic than males from T9 to L2 (T11 excluded) with a cumulative mean difference of 8.8 degrees ; (b) females had a significantly relatively thinner lumbar spinous processes and (c) females had a relatively wider superior interfacet distance (T9-T10 and L1-L4) than males. We conclude that the combination of less kyphotic VB wedging in the lower thoracic and upper lumbar vertebrae, relatively greater interspinous space and larger interfacet width in the lumbar spine in females are key architectural elements in the lumbar hyperlordosis in females and may compensate for the bipedal obstetric load during pregnancy.

Schmorl's nodes distribution in the human spine and its possible etiology.

Although Schmorl's nodes (SNs) are a common phenomenon in the normal adult population, their prevalence is controversial and etiology still debatable. The objective was to establish the spatial distribution of SNs along the spine in order to reveal its pathophysiology. In this study, we examined 240 human skeleton spines (T4-L5) (from the Hamann-Todd Osteological Collection) for the presence and location of SNs. To determine the exact position of SNs, each vertebral body surface was divided into 13 zones and 3 areas (anterior, middle, posterior). Our results show that SNs appeared more frequently in the T7-L1 region. The total number of SNs found in our sample was 511: 193 (37.7%) were located on the superior surface and 318 (62.3%) on the inferior surface of the vertebral body. SNs were more commonly found in the middle part of the vertebral body (63.7%). No association was found between the SNs location along the spine and gender, ethnicity and age. This study suggests that the frequency distribution of SNs varies with vertebra location and surface. The results do not lend support to the traumatic or disease explanation of the phenomenon. SNs occurrences are probably associated with the vertebra development process during early life, the nucleus pulposus pressing the weakest part of the end plate in addition to the various strains on the vertebrae and the intervertebral disc along the spine during spinal movements (especially torsional movements).

The influence of impact direction and axial loading on the bone fracture pattern.

The effect of the direction of the impact and the presence of axial loading on fracture patterns have not yet been established in experimental 3-point bending studies. PURPOSE: To reveal the association between the direction of the force and the fracture pattern, with and without axial loading. MATERIAL AND METHODS: A Dynatup Model POE 2000 (Instron Co.) low energy pendulum impact machine was utilized to apply impact loading on fresh pig femoral bones (n=50). The bone clamp shaft was adjusted to position the bone for three-point bending with and without additional bone compression. Four different directions of the force were applied: anterior, posterior, lateral, and medial. RESULTS: The impacted aspect can be distinguished from the non-impacted aspects based on the fracture pattern alone (the most fractured one); the impact point can be identified on bare bones (the area from which all oblique lines radiate and/or the presence of a chip fragment). None of our experiments (with and without compression) yielded a "true" butterfly fracture, but instead, oblique radiating lines emerged from the point of impact (also known as "false" butterfly). Impacts on the lateral and anterior aspects of the bones produce more and longer fracture lines than impacts on the contralateral side; bones subjected to an impact with axial loading are significantly more comminuted and fragmented. Under axial loading, the number of fracture lines is independent of the impact direction. Our study presents an experimental model for fracture analysis and shows that the impact direction and the presence of axial loading during impact significantly affect the fracture pattern obtained.

The impact velocity and bone fracture pattern: Forensic perspective.

Studies on bone-energy interaction are meager and revealed only a general correlation between the fracture pattern and the mechanism of the insult. This study has two objectives, to establish a usable fracture analysis method and to reveal the association between the energy of the force and the fracture pattern. Dynatup Model POE 2000 (Instron Co.) low energy pendulum impact machine was utilized to apply impact loading on fresh pig femoral bones (n=30). The bone clamp shaft was adjusted to position the bone for three-point bending with additional bone compression. Three different velocities of the forced applied were carried out. On average, the number, length and the curviness of the fracture lines created under moderate and high-energy impact is significantly higher compared to a low-energy impact. Most fractures lines were located on the impacted aspect in bones subjected to moderate- and high-velocity impact. Four oblique-radial fracture lines running from the point of impact creating a double butterfly pattern were found in bones subjected to moderate and high-velocity impact. Only "false" wedge-shaped (butterfly) fragments were found in the current study. Our results suggest an association between fracture pattern and the velocity of the impact.

Computed tomography-enhanced anatomy course using enterprise visualization.

Rapid changes in medical knowledge are forcing continuous adaptation of the basic science courses in medical schools. This article discusses a three-year experience developing a new Computed Tomography (CT)-based anatomy curriculum at the Sackler School of Medicine, Tel Aviv University, including describing the motivations and reasoning for the new curriculum, the CT-based learning system itself, practical examples of visual dissections, and student assessments of the new curriculum. At the heart of this new curriculum is the emphasis on studying anatomy by navigating inside the bodies of various living individuals utilizing a CT viewer. To assess the students' experience with the new CT-based learning method, an anonymous questionnaire was administered at the end of the course for three consecutive academic years: 2008/2009, 2009/2010, 2010/2011. Based upon the results, modifications were made to the curriculum in the summers of 2009 and 2010. Results showed that: (1) during these three years the number of students extensively using the CT system quadrupled (from 11% to 46%); (2) students' satisfaction from radiologists involvement increased by 150%; and (3) student appreciation of the CT-based learning method significantly increased (from 13% to 68%). It was concluded that discouraging results (mainly negative feedback from students) during the first years and a priori opposition from the teaching staff should not weaken efforts to develop new teaching methods in the field of anatomy. Incorporating a new curriculum requires time and patience. Student and staff satisfaction, along with utilization of the new system, will increase with the improvement of impeding factors.

The epiphyseal ring: a long forgotten anatomical structure with significant physiological function.

STUDY DESIGN: A descriptive study of the epiphyseal ring's structural design along the thoracolumbar spine. OBJECTIVE: To characterize and analyze the shape and size of the epiphyseal ring, to better understand its function. SUMMARY OF BACKGROUND DATA: The literature is lacking in metrical data pertaining to the epiphyseal ring that is usually described as a narrow bony labrum on which the external fibers of the anulus fibrosus are anchored. Most researchers express doubts as to whether the term epiphysis is justified in this case. METHODS: The sample studied included 240 human skeletons (vertebrae T4-L5) from a normal adult population (divided by sex, ethnicity, and age). Measurements of the vertebral body and epiphyseal ring were taken using a digital caliper at four different locations: anterior, posterior, right, left. In addition, each vertebral surface was photographed and the epiphyseal ring area measured (using image analyzer software Image J). RESULTS: We found that relative to vertebral body size throughout the thoracolumbar spine, the anterior section of the ring was the widest and the posterior section the narrowest. The lateral parts presented intermediate values. Relative to the discal area, the epiphyseal ring area gradually decreased from T7 to T12 and increased from T12 to L4. The area of the inferior ring was always larger than the superior ring (significant only for lumbar vertebrae), regardless of sex, ethnicity, and age. CONCLUSION: The epiphyseal ring varies largely in size and shape along the thoracolumbar spine. Much of its metrical properties are dictated by the applied mechanical stress regime during various movements, and/or the general anatomic structure of the spine.

Hyperostosis frontalis interna and androgen suppression.

Although hyperostosis frontalis interna (HFI) has been documented in the medical literature for over 300 years, its etiology remains undetermined. It is generally assumed to be associated with hormonal disturbances of the gonads. The aim of this study was to examine the association between androgen deprivation and development of HFI in males. Two groups of males over 60-years old were compared: a control group that included 180 healthy males, 45 suffering from benign prostatic hypertrophy (BPH) and a study group of 127 males with prostate cancer: 67 who received complete androgen block treatment, and 60 who received different treatments or none at all. CT head scans were used to identify and classify HFI (Brilliance 64, Philips Medical Systems, slice thickness 3 mm x 1.5 mm). It was found that males who received a complete androgen block manifested significantly higher prevalence of HFI compared to healthy males. However, no significant difference in HFI prevalence was found between males suffering from BPH and healthy males or males with prostate cancer who had not received a complete androgen block. A positive association between length of hormonal treatment and manifestation of HFI was shown. It can be concluded that BPH does not promote development of HFI; males who are hormonally treated for prostate cancer are at a higher risk of developing HFI compared to healthy males; the longer the duration of hormonal treatment, the higher the risk of developing HFI.

Ligamentum flavum thickness in normal and stenotic lumbar spines.

STUDY DESIGN: A descriptive computed tomography (CT) study of the ligamentum flavum (LF) thickness in individuals with normal and stenotic lumbar spines. OBJECTIVE: To establish standards for normal and pathologic range of LF thickness and its asymmetry as indicated in CT images and to examine its association with vertebral body size, age, and gender. SUMMARY OF BACKGROUND DATA: LF lines a considerable part of the posterior and lateral walls of the spinal canal and is a major role contributor to spinal canal stenosis. Due to methodologic deficiencies (e.g., small sample size, lack of control for vertebral body size, gender, and age), the normal range of LF thickness is still controversial. Furthermore, data on important aspect of LF thickness such as left-right differences are missing. METHODS: Two groups of individuals were studied. The first group included 65 individuals with lumbar spinal stenosis (LSS) (mean age: 66 +/- 9.7 years) and the second, 150 individuals (mean age: 52 +/- 19 years) without LSS-related symptoms. LF thickness was measured on CT images (Philips Brilliance 64), obtained from axial plane scan at the intervertebral disc level. Measurements were performed at the levels of L3-L4, L4-L5, and L5-S1. Analysis of variance and t test were carried out to evaluate the association between LF thickness and demographic factors. RESULTS: Absolute and relative LF thickness were significantly greater in the LSS group at the levels of L3-L4 and L4-L5 on both sides, compared to control group (P < 0.05). LF thickness was independent of gender (absolute and relative thickness). Even though LF thickness at all levels significantly increases with age, significant changes after the age of 60 occurred only at L3-L4. Significant asymmetry in LF thickness was found at L3-L4 (2.9 +/- 0.90 mm on the right vs. 2.76 +/- 0.90 mm on the left) and L5-S1 (3.42 +/- 1.1 mm on the right vs. 3.22 +/- 1.22 mm on the left) (P < 0.05). CONCLUSION: LF thickness is an age-dependent and gender-independent phenomenon. LF is significantly thicker on the right side. The borderline between normal and pathologic LF thickness should not be set at 4 mm.

Facet asymmetry in normal vertebral growth: characterization and etiologic theory of scoliosis.

STUDY DESIGN: The shape and orientation of the thoracic and lumbar zygapophyseal facets at the T1-L5 level in children were measured and analyzed. OBJECTIVE: To detect the pattern of zygapophyseal facet asymmetry in the thoracic and lumbar spines in children. SUMMARY OF BACKGROUND DATA: Whereas many studies have defined the pattern of zygapophyseal facet asymmetry in adults, there is insufficient data in children. METHODS: A 3-dimensional digitizer was used to measure zygapophyseal facet size, topography (length, width, concavity, convexity, and lateral interfacet height), and orientation (transverse and sagittal facet angles) at the T1-L5 level. Thirty-two complete, nonpathologic skeletons of children (age range from 4 to 17 years), housed at the Hamman-Todd Human Osteological Collection (Cleveland Museum of Natural History, Cleveland, OH) were assessed. Statistical analysis included paired t tests and analysis of variance. RESULTS: In general, zygapophyseal facet asymmetry in children exists only in the superior facets of the thoracic spine and is independent of age: The right superior facet is significantly shorter than the left in all thoracic vertebrae T1-T12 (up to -2.91 mm at T1), and significantly wider than the left in thoracic vertebrae T1-T9 (T8 excluded) (P < 0.003). The right superior transverse and sagittal facet angles are significantly greater than the left in thoracic vertebrae T1-T11, indicating a lesser inclination (in the sagittal plane) and more frontally positioned facet (in the transverse plane) (P < 0.003). Facet asymmetry was not evident in the superior or inferior facets of the lumbar vertebrae. CONCLUSION: Facet asymmetry in thoracic vertebrae appears in early childhood. The pattern of this asymmetry differs from that reported for adults and may be considered as a possible contributing etiological factor in the development of different types of idiopathic scoliosis.

Orientation of the human sacrum: anthropological perspectives and methodological approaches.

Discovering the nature of sacral orientation is of considerable anthropological importance. Therefore, this study aims at presenting a new anthropologically based definition for sacral anatomical orientation (SAO) angle, establishing standards of SAO for human population; examining the relationship between pelvic incidence (PI) and SAO; and associating SAO with demographic parameters. The study population consisted of 424 adult and 14 sub-adult (13-18 years, for SAO only) pelvises. Sacral orientation was measured using two different definitions: a) SAO is the angle created between the intersection of a line running parallel to the superior surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior edge of the symphysis pubis; b) PI is the angle created between the perpendicular to the sacral plate at its midpoint and the line connecting this point to the middle of the axis of the acetabulum. SAO was measured using a specially designed mechanical measurement tool and a 3D digitizer. PI was measured via the 3D digitizer. The methods developed by us for measuring SAO and PI in skeletal material are valid and reliable. SAO and PI measures were highly correlated (r = -0.824, P < 0.001). The average SAO was 49.01 degrees (SD = 10.16), and the average PI 54.08 degrees (SD = 12.64). SAO was independent of ethnicity and sex, yet age dependent. This study establishes a methodology for estimating SAO and PI in skeletal material and furnishes the anthropological milieu with base line data regarding these parameters. Future studies in human evolution can greatly benefit from this study.