Dimensions of cervical vertebral bodies according to age and sex

Sex- and Age-related Differences in Spinal Degeneration: An Anatomical and Magnetic Resonance Imaging Study of the Human Spine

Objectives:

A precise anatomical understanding of the morphology of the spine is indispensable for neck and low back pain therapy including rehabilitation. However, few studies have directly addressed spinal morphology with a focus on the height of the vertebral body and discs. The aim of the current study was to analyze sex- and age-related changes in the spine by measuring the distance between adjacent centers of the intervertebral disc spaces from the posterior aspect in cadavers and by using magnetic resonance imaging (MRI) measurements at the cervical and lumbar vertebral levels.

Methods:

In the cadaveric study, the posterior distance between the adjacent centers of the disc spaces was measured for 58 spinal canals. The equivalent distances were examined using MRI in 370 and 660 subjects who presented with neck pain and back pain, respectively.

Results:

The distance between the adjacent centers of the intervertebral disc spaces in male cadavers was larger than that in female cadavers from C3 to L5/S1. The MRI results showed that the distance between the adjacent centers of the intervertebral disc spaces decreased with age in all spinal areas in men and women. Cadaveric values were significantly lower than the MRI values in men, whereas in women, no significant differences were observed.

Conclusions:

These results suggest that age-related changes in the cervical and lumbar spine are associated with differences between men and women in the degrees of progressive vertebral body and disc degeneration.

Sagittal wedging of intervertebral discs and vertebral bodies in the cervical spine and their associations with age, sex and cervical lordosis: A large-scale morphological study

Many recent studies have focused on the functional and clinical importance of cervical lordosis. However, there is little accurate knowledge of the anatomical parameters that constitute cervical lordosis (i.e., the sagittal wedging angles of intervertebral discs and vertebral bodies) and their associations with age and sex. Standing lateral cervical radiographs of 1020 subjects (424 males, 596 females) with a mean age of 36.6 ± 17.0 years (range 7-95 years) were evaluated retrospectively. Cervical lordosis, the sum of intervertebral disc wedging angles from C2/C3 to C6/C7 and the sum of vertebral body wedging angles from C3 to C7 were measured. The sum of intervertebral disc wedging and the sum of vertebral body wedging were 20.6° ± 14.7° and -12.8° ± 10.3°, respectively. The sum of intervertebral disc wedging increased significantly with age and was significantly greater in males than females, whereas there was no sex-related difference in the sum of vertebral body wedging. The sum of intervertebral disc wedging was negatively correlated with sum of vertebral body wedging. Wedging of discs contributed to C2-C7 cervical lordosis more significantly than wedging of vertebral bodies. There were moderate positive correlations between cervical lordosis and intervertebral disc wedging angles at C3/C4, C4/C5 and C5/C6; weak correlations were observed at C2/C3 and C6/C7. This study constitutes the largest currently available analysis comprehensively documenting the anatomical characteristics of sagittal wedging of intervertebral discs and vertebral bodies in the cervical spine. The findings could improve understanding of the internal architecture of cervical lordosis among clinicians.

Forensic sex estimation using the vertebrae: an evaluation on two European populations

Sex estimation is one of the primary steps for constructing the biological profile of skeletal remains leading to their identification in the forensic context. While the pelvis is the most sex diagnostic bone, the cranium and other post-cranial elements have been extensively studied. Earlier research has also focused on the vertebral column with varying results regarding its sex classification accuracy as well as the underlying population specificity. The present study focuses on three easily identifiable vertebrae, namely T1, T12, and L1, and utilizes two modern European populations, a Greek and a Danish, to evaluate their forensic utility in sex identification. To this end, 865 vertebrae from 339 individuals have been analyzed for sexual dimorphism by further evaluating the effects of age-at-death and population affinity on its expression. Our results show that T1 is the best sex diagnostic vertebra for both populations reaching cross-validated accuracy of almost 90%, while age-at-death has limited effect on its sexual dimorphism. On the contrary, T12 and L1 produced varying results ranging from 75 to 83% accuracy with the Greek population exhibiting distinctively more pronounced sexual dimorphism. Additionally, age-at-death had significant effect on sexual dimorphism of T12 and L1 and especially in the Greek female and Danish male groups. Our results on inter-population comparison suggest that vertebral sex discriminant functions, and especially those utilizing multiple measurements, are highly population specific and optimally suitable only for their targeted population. An open-source software tool to facilitate classifying new cases based on our results is made freely available to forensic researchers.

Intramuscular innervation patterns of the splenius capitis and splenius cervicis and their clinical implications for botulinum toxin injections

INTRODUCTION

The purpose of this study was to clearly characterize the intramuscular nerve distributions of the splenius capitis and splenius cervicis muscles that are both responsible for the onset of a chronic tension type headache and to use this information to identify the effective botulinum toxin (BoNT) injection sites.

MATERIALS AND METHODS

Ten splenius capitis and splenius cervicis specimens were subjected to Sihler's staining to reveal intramuscular nerve arborization patterns and determined the optimal location for BoNT injection.

RESULTS

Nerve distribution patterns in the splenius capitis were identified as nerve pathways that travel down toward the origin point and others that travel up toward the insertion point. This neuromuscular innervation from the central (50%) point was distributed evenly in these two directions. The neural pathways of splenius cervicis traveled vertically from the insertion point to the origin point. If the length from the muscle origin point to the insertion point is normalized to 100%, motor neurons innervate the muscle from around the 30% to the 70% point.

CONCLUSIONS

The safest and most-effective BoNT injection sites for the splenius capitis and splenius cervicis were found at around the 50% point and the 30% to the 70% point, respectively.

Clinical presentation and outcome after anterior cervical discectomy and fusion for degenerative cervical disc disease

Background:

Anterior cervical discectomy and fusion (ACDF) is a well-described surgical approach for symptomatic degenerative cervical disc disease which does not respond to conservative management. In the present study, we assessed clinical presentation and outcomes of ACDF.

Materials and Methods:

The present study was conducted from October 1, 2015, to October 31, 2017, in the Department of Neurosurgery, Narayana Medical College and Hospital, Nellore, Andhra Pradesh, among 100 consecutive adult patients who underwent single- or two-level ACDF for degenerative cervical disc disease.

Results:

The mean age was 47.2 ± 12.8 years (range: 20–74 years). Majority of the patients were male (86/100). Presenting symptoms were neck pain (77%), limb weakness (73%), paresthesias (53%), radicular pain (49%), stiffness in limbs (16%), and bladder involvement (13%). Fusion was done with stand-alone titanium cage/bone graft or titanium cage/bone graft with anterior cervical plate. At the time of discharge, significant improvement in preoperative symptoms (neck pain [47/77-61%], radicular pain [31/49-63%], limb weakness [53/73-72.6%], paresthesias [44/53-83%], stiffness in limbs [13/16-81%], and bladder symptoms [8/13-61%]) was reported by majority of these patients. Majority of these patients also reported improvement in preoperative sensory deficits at the time of discharge. Postoperative complications were hoarseness of voice (22%), dysphagia (16%), deterioration of motor power (8%), and postoperative hematoma (7%).

Conclusions:

A significant proportion of patients with degenerative cervical disc disease show remarkable recovery after ACDF.

Three-dimensional kinematic corridors of the head, spine, and pelvis for small female driver seat occupants in near- and far-side oblique frontal impacts

OBJECTIVES

Analyses of recent automotive accident data indicate an increased risk of injury for small female occupants compared to males in similar accidents. Females have been shown to be more susceptible to spinal injuries than males. To protect this more vulnerable population, advanced anthropomorphic test devices (ATDs) and computer human body models are being developed and require biofidelity curves for validation. The aim of this study is to generate female-specific 3D kinematic corridors in near- and far-side oblique frontal impacts for the head, spine, and pelvis.

METHODS

Eight specimens were procured and prescreened for mass, stature, and quantitative computed tomography bone mineral density and preexisting injuries to minimize biologic variability. Sets of 4 noncolinear retroreflective targets were placed on the back of the head; dorsal spine at T1, T8, and L2; and posterior sacrum. Instrumented computed tomography scans were obtained to measure the orientation and position of the markers relative to anatomic fiducials. The specimens were placed on a buck representative of a generic automotive driver's seat environment designed to minimize lower-extremity and pelvic motion. The buck was oriented such that the buck centerline was seated 30° from the impact vector in either a near- or far-side oblique frontal configuration. Preposition of the occupant was specified to the 50th percentile male H-point location, thigh and tibial angles, and torso angle. Impact was delivered via a servo-acceleration sled to the base of the buck with a 30 km/h 9 g trapezoidal pulse. Occupants were restrained by a standard 3-point belt that had a custom load-limiter device set to 2 kN at the D-ring side of the shoulder belt. Target motion was recorded at 1 kHz using a 3D optical motion capture system. Anatomic motion of the head, spine, and pelvis was calculated relative to the seat, and the average response was determined from 4 near-side and 4 far-side tests. The borders of the corridor were determined by calculating a standard deviational ellipse in the x, y, and z planes at each time step.

RESULTS

Plots of the biofidelity corridors for near- and far-side tests are shown in planes parallel to the seat from the lateral, rear, and overhead directions. Averaged peak excursions in the fore/aft and lateral directions are compared for the near- and far-side corridors. Near-side female and male tests are similarly compared.

CONCLUSIONS

In general, average peak excursions were greater in the far-side configuration than in the near-side configuration. Peak excursion results compared well with similar tests conducted on male postmortem human subjects (PMHS). The kinematic corridors developed in the current study serve as a set of biofidelity corridors for the development of current and future physical and computational surrogates.

Male and Female Cervical Spine Biomechanics and Anatomy: Implication for Scaling Injury Criteria

There is an increased need to develop female-specific injury criteria and anthropomorphic test devices (dummies) for military and automotive environments, especially as women take occupational roles traditionally reserved for men. Although some exhaustive reviews on the biomechanics and injuries of the human spine have appeared in clinical and bioengineering literatures, focus has been largely ignored on the difference between male and female cervical spine responses and characteristics. Current neck injury criteria for automotive dummies for assessing crashworthiness and occupant safety are obtained from animal and human cadaver experiments, computational modeling, and human volunteer studies. They are also used in the military. Since the average human female spines are smaller than average male spines, metrics specific to the female population may be derived using simple geometric scaling, based on the assumption that male and female spines are geometrically scalable. However, as described in this technical brief, studies have shown that the biomechanical responses between males and females do not obey strict geometric similitude. Anatomical differences in terms of the structural component geometry are also different between the two cervical spines. Postural, physiological, and motion responses under automotive scenarios are also different. This technical brief, focused on such nonuniform differences, underscores the need to conduct female spine-specific evaluations/experiments to derive injury criteria for this important group of the population.

Fatigue responses of the human cervical spine intervertebral discs

Numerous studies have been conducted since more than fifty years to understand the behavior of the human lumbar spine under fatigue loading. Applications have been largely driven by low back pain and human body vibration problems. The human neck also sustains fatigue loading in certain type of civilian occupational and military operational activities, and research is very limited in this area. Being a visco-elastic structure, it is important to determine the stress-relaxation properties of the human cervical spine intervertebral discs to enable accurate simulations of these structures in stress-analysis models. While finite element models have the ability to incorporate viscoelastic material definitions, data specific to the cervical spine are limited. The present study was conducted to determine these properties and understand the responses of the human lower cervical spine discs under large number of cyclic loads in the axial compression mode. Eight disc segments consisting of the adjacent vertebral bodies along with the longitudinal ligaments were subjected to compression, followed by 10,000 cycles of loading at 2 or 4Hz frequency by limiting the axial load to approximately 150 N, and subsequent to resting period, subjected to compression to extract the stress-relaxation properties using the quasi-linear viscoelastic (QLV) material model. The coefficients of the model and disc displacements as a function of cycles and loading frequency are presented. The disc responses demonstrated a plateauing effect after the first 2000 to 4000 cycles, which were highly nonlinear. The paper compares these responses with the "work hardening" phenomenon proposed in clinical literature for the lumbar spine to explain the fatigue behavior of the discs. The quantitative results in terms of QLV coefficients can serve as inputs to complex finite element models of the cervical spine to delineate the local and internal load-sharing responses of the disc segment.

Risk factors in cervical spondylosis

BACKGROUND

Cervical spondylosis is essentially a degenerative disorder common after fourth decade. It has been seen that radiological evidence of cervical spondylosis do not necessarily co-relate with clinical findings. This discrepancy has been attributed to the morphometric dimensions of the vertebrae, age, sex, race, occupation, weight and height of the patients.

OBJECTIVE

The objective of this study is to co-relate the variables like age, sex, race, occupation, vertebral body diameter, canal diameter, canal body ratio of cervical spine vertebrae with cervical spondylosis cases with normal population.

METHODS

In this hospital based, case control, consent based, cross-sectional, clinico-radiological study 200 individuals (controls-100, cases-100) who were subjected to lateral projection radiographs of cervical spine. Their age, sex, race, occupation, height, weight and mid-sagittal canal diameter (CD), sagittal vertebral body diameter (VBD) and the canal-body ratio (CBR) of the cervical vertebrae was recorded and analyzed statistically.

RESULTS

There was no relation between vertebral dimensions and clinical groups. In radiculopathy group, age and height showed significance on univariate analysis. While only age remained significant on multivariate analysis. In neck pain group age, sex, and height showed significance on univariate analysis while in multivariate analysis age, sex and occupation were significant risk factors.

Sexual dimorphism in the 7th cervical and 12th thoracic vertebrae from a Mediterranean population

Sex determination is an important task in physical anthropology and forensic medicine. The study sample comprised 121 individuals of known sex, age, and cause of death from San Jose cemetery in Granada (Spain). Eight dimensions were analyzed, and discriminant function analysis was performed for each vertebra to obtain discriminating functions and study the percentage of correct assignations of these functions. The percentage accuracy was approximately 80% for both vertebrae, but varied according to the sex, being higher for the 7th cervical in males and higher for the 12th thoracic in females. As reported in other populations, the greatest dimorphism values were found for the length of the inferior surface of the vertebral body and the width and length of the vertebral foramen of the 7th cervical vertebra and for the length of the inferior surface of the vertebral body of the 12th thoracic vertebra.

Head and neck anthropometry, vertebral geometry and neck strength in height-matched men and women

Women have an increased incidence of whiplash injury and neck pain compared to men. Physical and numerical models represent one avenue to explore and potentially explain these gender differences, but a valid model of the female neck does not yet exist. A fundamental question in the development of a female neck model is whether female necks are simply scaled versions of male necks, or whether there are significant inter-gender geometrical differences. The goal of this study was to quantify differences in head and neck geometry and neck strength in pairs of male and female subjects matched for standing height and neck length. Based on 14 matched pairs of men and women, we found that most head and neck anthropometric parameters were significantly smaller in females compared to males. Moreover, gender differences in a number of neck anthropometry parameters (an average of 9-16% smaller in females) were larger than differences in head anthropometry parameters (an average of 3-6% smaller in females). Female vertebrae between C3 and C7 were significantly smaller than male vertebrae in the anterior-posterior dimension (p < 0.012) but not in the medial-lateral dimension (p > 0.07). Female necks were also significantly weaker than male necks (32% weaker in flexion and 20% weaker in extension; p < 0.001), and these strength differences corresponded well to those predicted solely from the observed geometric differences. These results demonstrate that male and female necks are not geometrically similar and indicate that a female-specific model will be necessary to study gender differences in neck-related disorders.

Costal process of the first sacral vertebra: Sexual dimorphism and obstetrical adaptation

The human sacrum is sexually dimorphic, with males being larger than females in most dimensions. Previous studies, though, suggest that females may have a longer costal process of the first sacral vertebra (S1) than males. However, these studies neither quantified nor tested statistically the costal process of S1. This study compares S1 with the five lumbar vertebrae (L1 to L5) for a number of metric dimensions, including costal process length. Four issues are addressed, the: 1) hypothesis that females have a longer costal process of S1 than males; 2)hypothesis that homologous structures (i.e., costal processes of L1 to S1) differ in their direction of sexual dimorphism; 3) importance of the costal process of S1 to the obstetrical capacity of the pelvis; and 4) evolution of sexual dimorphism in costal process length of S1. One hundred ninety-seven individuals, including males and females of American blacks and whites, from the Hamann-Todd and Terry Collections were studied. Results show that males are significantly larger than females for most vertebral measurements, except that females have a significantly longer costal process of S1 than males. Costal process length of S1 is positively correlated with the transverse diameter and circumference of the pelvic inlet. The magnitude of sexual dimorphism in costal process length of S1 ranks this measure among the most highly dimorphic of the pelvis. Compared with the humans in this study, australopithecines have a relatively long costal process of S1, but their broad sacrum was not associated with obstetrical imperatives.

Sexual dimorphism in degenerative disorders of the spine

Sexual dimorphism is evident during formation, growth, and development of the spine. Pregnancy alters spine physiology and is a risk factor for back pain. The processes of aging and spinal degeneration adversely affect men and women slightly differently. Although degenerative changes are observed at similar rates in both sexes, women seem to be more susceptible to degenerative changes leading to instability and malalignment, structural deterioration, such a stenosis or disc degeneration. Surgical satisfaction is greater in men, which has been attributed to poorer preoperative function secondary to more advanced disease at time of surgery and lower patient expectations for clinical improvement, both observed in women.

Cervical spine geometry in the automotive seated posture: variations with age, stature, and gender

In the mid 1970s, UMTRI investigated the biomechanical properties of the head and neck using 180 "normal" adult subjects selected to fill eighteen subject groups based on age (young, mid-aged, older), gender, and stature (short, medium, and tall by gender). Lateral-view radiographs of the subjects' cervical spines and heads were taken with the subjects seated in a simulated automotive neutral posture, as well as with their necks in full-voluntary flexion and full-voluntary extension. Although the cervical spine and lower head geometry were previously measured manually and documented, new technologies have enabled computer digitization of the scanned x-ray images and a more comprehensive and detailed analysis of the variation in cervical spine and lower head geometry with subject age, stature, and gender. After scanning the radiographic images, 108 skeletal landmarks on the cervical vertebrae and 10 head landmarks were digitized. The resulting database of cervical spine and head geometry was used to study cervical spine curvature, vertebral dimensions, and head/neck orientation as functions of age, gender, and stature. The data were used to characterize neutral posture cervical spine curvatures using two methods: a curvature index and Bézier spline functions. Lateral-view vertebral dimensions were also calculated for each subject, and a cascading series of equations was developed to estimate vertebral size and shape for a selected age, stature, and gender. The orientation of the cervical spine was defined using a neck chord angle, where the neck chord was varied to use different anatomical landmarks and estimates of joint centers for the top and bottom of the neck chord. Results from the study have been incorporated into a MS-Access based software package that allows researchers and modelers to generate cervical spine geometries for occupants of a specified age, gender, and stature. The program allows selection of individual occupants from the database that meet age, stature, gender, or curvature criteria, or creation of a composite cervical spine geometry representative of the selected age, gender, and stature. This tool will allow researchers to configure and vary cervical spine geometry in computer models and experimental test setups used to study head and neck impact response and injury risk.

Morphologic Evaluation of Cervical Spine Anatomy with Computed Tomography

The computed tomography (CT) studies of the cervical spine from 50 males and 50 females were reviewed to provide morphometric data on a variety of anatomic parameters relevant to anterior cervical reconstruction and fixation. Measurements were made of the vertebral body width and midsagittal anteroposterior (AP) diameter and the distance between the medial borders of the longus coli muscles. Distances between adjacent endplates were also measured, both at their midpoint and at the anterior margin. Widths of the vertebral bodies measure 24.6 +/- 2.4 and 23.0 +/- 2.4 mm in males and females, respectively, with the narrowest measuring 17 and 14, respectively. The average midsagittal AP diameter of each vertebral body in males was approximately 17-18 mm, with the smallest AP diameter measured to be 13 mm. The average midsagittal AP diameter of each vertebral body in females was approximately 15-16 mm, with the smallest being 10 mm. CT scanning provides excellent osseous detail for the measurement of such parameters, and with its widespread use in the evaluation of cervical disorders, large numbers of patients can be reviewed.

Medicolegal anthropology in France

Medicolegal anthropology has a very long history in France. Basic studies on human skeletal remains started as early as the 18th century. The 19th century produced many medical theses and research papers on age, sex, as well as stature estimation. The research proliferated in the first 60 years of the 20th century, much of which is still in use in France and abroad. The later half of the 20th century, however, was dormant in research on human skeletal biology at a time when forensic anthropology was becoming an active field worldwide. In the last decade, medicolegal anthropology took a different perspective, independent of its traditional roots. Research and practice have both been in the professional domain of forensic physicians unlike the situation in many other countries. Population based studies requiring large databases or skeletal collections have diminished considerably. Thus, most research has been on factors of individualization such as trauma, time since death, crime scene investigation, and facial reconstruction. It is suggested that there is a need for cooperation between the forensic physician and anthropologist to further research. This also encourages anthropologists to carry out research and practice that can fulfill the needs of the medicolegal system of the country.