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AN INVESTIGATION OF STAGES OF EPIPHYSEAL UNION
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MELISSA ANN TORPEY

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5/08 KLIProglAccaPres/CIRC/DateDue Indd

AN INVESTIGATION OF STAGES OF EPIPHYSEAL UNION IN THE CERVICAL
VERTEBRAE OF YOUNG ADULT SKELETONS

By

Melissa‘Ann Torpey

A THESIS
Submitted to
Michigan State University

in partial fiilfillment of the requirements
for the degree of

MASTER OF SCIENCE
Department of Forensic Science

2006

ABSTRACT

AN INVESTIGATION OF STAGES OF EPIPHYSEAL UNION IN THE CERVICAL
VERTEBRAE OF YOUNG ADULT SKELETONS

By
Melissa Ann Torpey

This research explored epiphyseal union of the cervical vertebral centra using a
previously developed aging technique for the thoracic and first two lumbar vertebrae. In
forensic anthropology, age estimation is an important aspect of developing a biological
profile in cases of unknown identity. The timing and rate of epiphyseal union for the
cervical vertebrae is studied to determine its relationship to known age of the decedents
in the sample. Results from cervical vertebral ring epiphyseal union are compared to
results of thoracic and first two lumbar vertebrae from a previous study to determine if
the rate and pattern of epiphyses of the centra are similar or different. This study
demonstrates that aging an individual through observations of cervical vertebral centra
epiphyseal union is as accurate and reliable as using thoracic and first two lumbar
vertebrae. Observations about the extent to which the union has progressed are important
in understanding the amount of time it takes for complete fusion to occur and any pattern
in how the fusion occurs. Observational and statistical analyses of the rate and pattern of
the progress of epiphyseal union of the cervical vertebral centra are performed. Results
from the analyses are significant and indicate an overall correlation of .781. The findings
are important in skeletal age estimation both forensically and archaeologically in that
they will help narrow what would otherwise be a broad age range, can be used to
corroborate findings from other skeletal sites, and can be helpful in the absence of other

key skeletal indicators of age.

Cepyright by
MELISSA ANN TORPEY
2006

Dedicated to:
My family who have proved to be

my sole support, comfort, and love throughout the years.

iv

ACKNOWLEDGMENTS

I would like to thank Lyman J ellema in the Physical Anthropology section of the
Cleveland Museum of Natural History for his assistance in collecting the data for this
research. I would also like to thank Dr. A. Midori Albert for her constant motivation and '
inspiration to complete my research, follow a dream, and persevere. A special thanks to
Dr. Christina DeJong for her guidance in the statistical analysis for this research.
Moreover, my gratitude extends to Drs. Norman J. Sauer and Todd Fenton for enabling
me to expand, as well as fine tune, my knowledge of anthropology and forensic science

in the classroom, and for supervising my research.

TABLE OF CONTENTS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LIST OF TABLES ................................................................................. viii
LIST OF FIGURES ................................................................................. ix
Chapter 1: Introduction - 1
Aging 2
Vertebral Aging 3
Chapter 2: An Overview of Skeletal Age Estimation Methods for Young Adults ..... 5
Third Molar Development 5
Long Bone Epiphyses 6
Pubic Symphysis 7
Sternal Rib Ends 7
Radiographic vs. Anthroposcopic Techniques 8
Chapter 3: Vertebral Ossification 11
Primary Centers of Ossification 11
Secondary Centers of Ossification 13
Chapter 4: Vertebral Ring Epiphyseal Union 15
Chapter 5: Methods 21
Sample 21
Scoring the Progress of Vertebral Ring Union 2]
Analyses 23
Chapter 6: Results 24
Statistical Analyses 24
Observational Analyses 26
Stages ......................................................................................................................... 26
Patterns .............................................................................................. 29
Chapter 7: Discussion 31
Chapter 8: Conclusion- 34

 

vi

 

APPENDIX A

APPENDIX B

 

REFERENCES

 

vii

37

45

58

LIST OF TABLES

Table l —- Sample Demographics ................................................................. 21
Table 2 -— Statistical Analyses: Correlation Results ............................................ 26
Table 3 — Summary Observations of Vertebral Ring Epiphyseal Union Stages. . ..........29
Table 4a - Vertebral Ring Epiphyseal Union Data for Females .............................. 54
Table 4b — Vertebral Ring Epiphyseal Union Data for Females .............................. 55
Table 5a — Vertebral Ring Epiphyseal Union Data for Males ................................. 56
Table 5b — Vertebral Ring Epiphyseal Union Data for Males ................................. 57

viii

LIST OF FIGURES

Figure 1 — Cervical Aspect of the Vertebral Column .......................................... 38
Figure 2 — Characteristics of the Second Cervical Vertebra ................................... 39
Figure 3 — Characteristics ofa Typical Cervical Vertebra (C3-C7). . ..........40
Figure 4 — Primary Centers of Ossification of the Second Cervical Vertebra ............... 41
Figure 5 — Primary Centers of Ossification of a Typical Cervical Vertebra ................ 41
Figure 6 — Secondary Centers of Ossification of a Typical Cervical Vertebra ............. 42
Figure 7 — Correlation between Mean Stage of Vertebral Ring Epiphyseal Union and

Age for Females and Males ........................................................... 43
Figure 8 — Overall Correlation of Mean Stage of Vertebral Ring Epiphyseal Union and

Age ....................................................................................... 44
Figure 9 — Example of Stage 0 Vertebral Ring Epiphyseal Union (C7-S) ................... 46
Figure 10 — Stage 0 Vertebral Ring Epiphyseal Union (C4-I) ................................. 46
Figure 11 — Stage 0 Vertebral Ring Epiphyseal Union (C5) .................................. 47
Figure 12 — Example of Stage 1 Vertebral Ring Epiphyseal Union (C6-I) .................. 48
Figure 13 — Stage 1 Vertebral Ring Epiphyseal Union (C7-I) ................................. 48
Figure 14 — Stage 1 Vertebral Ring Epiphyseal Union (C6) .................................. 49
Figure 15 — Example of Stage 2 Vertebral Ring Epiphyseal Union (CS-I) .................. 50
Figure 16 - Stage 2 Vertebral Ring Epiphyseal Union (C3-S) ................................ 50
Figure l7 — Stage 2 Vertebral Ring Epiphyseal Union with Persistent Line between

Epiphyses and Centrum (C7) ........................................................ 51
Figure 18 — Example of Stage 3 Vertebral Ring Epiphyseal Union (C3-I) .................. 52
Figure 19 — Stage 3 Vertebral Ring Epiphyseal Union (C2-I) ................................. 52
Figure 20 — Stage 3 Vertebral Ring Epiphyseal Union; Full Adult Vertebra (C3) ......... 53

ix

Chapter 1

Introduction
“Science is, at its best, self-correcting and relentlessly self-critica ” (Marks, 2002).

The field of physical anthropology is continuously changing, and for its subfield,
forensic anthropology, change, correction, and improvement are of utmost importance.
One of the goals of a forensic anthropologist working on a case of unknown identity is to
develop, from skeletal analyses, a biological profile consisting of information on age, sex,
ancestry, and stature. The biological profile is often imperative in establishing a positive
identification for an unknown individual. One aspect of the biological profile that is
especially important for the process of identification is age estimation. There are
essentially two aspects to the methods for estimating age: (1) those based on skeletal
growth and dentition and (2) those based on the deterioration of the skeleton (Byers,
2005). Methods based on skeletal growth and dentition are associated with aging
children, generally 18 years and younger. Due to the rapid and regular growth of the
skeleton and changes in dentition and the tighter genetic control over these grth and
maturation processes throughout the subadult years, age ranges based on these methods
are usually narrower in subadults, and broader in adults. The deterioration of the skeleton
which begins in adulthood, or around 18 years of age produces larger estimated age
ranges due to the wide range of human variation. Age ranges must be decided upon
carefully because if the age range is too broad, it may be too inclusive, thereby being of
little use. If the age range is too narrow, it may exclude likely candidates for a positive

identification by eliminating the individual. The age estimation research in forensic

anthropology is often driven by efforts to arrive at the narrowest possible age ranges
within the scope of normal human variation.
Aging

Morphological changes in the skeleton are important indicators of age and are
used extensively in both forensic and archaeology casework in physical anthropology.
Generally, aging techniques revolve around the pelvis and the ribs for adults and long
bone growth and tooth development in subadults. Although teeth form and erupt in the
mouth at generally predictable ages, the third molar (Solari and Abramovitch, 2002) has
become less predictable, due to its greater genetic instability, highlighting the need for an
improved method to distinguish young adults and teenagers. The investigation of sex
differences in age-related morphological changes has important implications in forensic
anthropology, as well. Females generally develop and mature earlier than males (Pryor,
1923). Without information on skeletal development in females, criteria based solely on
males are often substituted to estimate age at death for females. Not knowing whether
growth or aging patterns in females and males are similar could be detrimental in the
identification of an individual because ages may be over or underestimated.

In order to help narrow otherwise broader estimated age ranges, past studies have
examined vertebral ring epiphyses because they fuse after long bone epiphyses and are
active in the early to mid 205. Investigated here are the stages and timing of the
epiphyseal union of the cervical vertebral ring epiphyses. Examining the cervical
vertebrae is unique in that no other study has previously focused solely on the timing and
rate of the epiphyseal union of the cervical vertebrae and its comparability to the rest of

the vertebral column. This study explored the epiphyseal rings of the cervical vertebrae

i and whether fUSiOIl occurs simultaneously or at different rates compared to the rest of the
vertebral column.
Vertebral Aging

The scoring method of epiphyseal union for the thoracic and first two lumbar
vertebrae developed by Albert and Maples (1995) was used in this study of cervical
vertebral aging. Utilizing this method enabled a unique look at the applicability,
consistency, and reliability of the Albert and Maples (1995) method as well as a general
comparison throughout the vertebral column. The presacral vertebral column consists of
seven cervical, 12 thoracic, and five lumbar vertebrae. Refer to Figure l on page 38 that
depicts the cervical aspect of the vertebral column. Each typical cervical vertebra (C3-
C7) possesses five epiphyses: one for each of the superior and inferior rings of the
centrum, one for each tip of the transverse process, and one for the spinous process. This
study focuses on epiphyseal rings. Due to the lack of a vertebral body for the first
cervical vertebrae or C1 and the superior surface of the second cervical vertebrae or C2,
the areas that are examined for this research are the inferior surface of the second and
both surfaces of the last five cervical vertebrae or C3-C7. The epiphyses appear around
puberty and the progression of union of the epiphyses can be used for the purpose of
skeletal aging. Previous research (Albert and Maples, 1995) has concentrated on
epiphyseal union of the centra of the thoracic and first two lumbar vertebrae due to the
older age maturation of vertebral rings. This is important for aging individuals beyond
age 18-20 where long bone epiphyses may be complete, but before skeletal maturation is
reached enabling the distinction between early and mid 208 and beyond. It should be

noted that a juvenile vertebral centrum is not equivalent to an adult vertebral body. The

adult vertebral body encompasses the centrum in addition to a small portion of the neural
arch on either side of the centrum (Scheuer and Black, 2004). This terminology will

become important in later discussions of growth and development.

Chapter 2

An Overview of Skeletal Age Estimation Methods for Young Adults

Age estimation of subadults and young adults is usually based on dental
development due to the strong correlation of human tooth development and eruption with
specific chronological ages (Pfau and Sciulli, 1994). When teeth are not available, other
methods are used such as long bone lengths and an analysis of epiphyseal fusion.
“Physiological age of the immature human skeleton must be assessed from one or more
of the following systems: appearance and union of epiphyses, bone size, the loss of
deciduous teeth, the eruption of teeth, and dental calcification” (Ubelaker, 1987; 1254).
However, these techniques can be more environmentally sensitive than dental
development causing more variation in the data and assessment of age. Methods of aging
subadults can involve either an anthroposcopic analysis or a radiographic analysis as
presented by Pfau and Sciulli (1994).

Third Molar Development

As an individual ages and possesses a full set of permanent teeth, tooth
development obviously becomes less helpful in an age assessment. The accuracy of tooth
development in determining age is best achieved when many teeth are undergoing growth
and development. Solari and Abramovitch (2002) report that age estimation becomes
increasingly difficult after age 14 due to most of the dentition being completely
developed at this time. However, the development of the third molar can still provide
evidence of chronological age. The third molars are the last teeth to erupt in human

development, but they are many times the most variable tooth in regards to time of

I formation and eruption. As a standard, third molar eruption denotes an age of 18 years or
more, but this assessment is continually becoming more unreliable (Mincer, et al., 1993).
Long Bone Epiphyses

The two most common methods of aging young adults are the development of the
third molar and long bone epiphyseal union, both of which are sufficient for estimating
an age of younger or older than 18 years. Although the timing of epiphyseal union varies
among different individuals, the epiphyses throughout the skeleton typically follow a
general sequence of union with the epiphyseal rings of the vertebral centra among the
later fusing of the epiphyses (Byers, 2005). Another of the later fusing epiphyses is the
medial end of the clavicle, but the clavicle is quite variable (Byers, 2005). Since, in
general, long bone epiphyses complete union by the age of 20 years, the later fusing
epiphyses such as the vertebral ring epiphyses can provide information on age beyond the
third molar and most other epiphyses (Byers, 2005). That the vertebral ring epiphyses
remain active later into the early to middle 205 extends the age range for which
epiphyseal union as a method of age estimation can be useful. As a later fusing
epiphysis, the vertebral ring epiphysis can provide narrower age ranges such as late teens,
early 203, and mid 208 rather than over or under 18 years of age (Byers, 2005).

Beyond the young adult years, age estimation of adult individuals is usually based
on skeletal indicators representing degeneration or remodeling. These changes are most
reliably observed on the pubic syrnphysis, fourth stemal rib end, and auricular surface.
However, the auricular surface is more complicated and challenging to employ, and

therefore, it is used less frequently.

Pubic Symphysis

The pubic symphyseal face, one of the most frequently used feature in the
estimation of age in adults, is effective in that changes occurring at this site better
correlate with chronological age than do other sites. It is most frequently used because
the pubic symphysis is considered the most reliable due to wide variation in other
methods such as dental wear or attrition and cranial suture closures. Also, the pubic
symphysis is used most frequently because of the apparent clarity in its age-related
changes thanks to important studies by T. Wingate Todd (1920, 1921), Brooks (1955),
and McKem and Stewart (1957). Todd’s studies revealed important findings and resulted
in the development of four phases correlating changes in the pubic symphysis to age
assessment. Phase one, denoting the earliest ages, begins with an age assessment of 25
years. After later statistical analyses, Todd’s ten-phase system was merged into the
Suchey-Brooks six—phase system. However useful these methods are in adult age
estimation, the beginning phases only begin at the age of 25 years, and are therefore, not
applicable to teenage and young adult skeletons.
Stemal Rib Ends

Another common adult aging technique was developed by Iscan and Loth (1986)
using the fourth stemal rib end. Iscan and Loth studied the changes in form, shape, and
texture over time to estimate an age progression. Four features of the stemal rib end
change over time: surface bone, surface contour, rim edge, and rim contour. These
features are used to describe the age phases established by Iscan and Loth to result in a
reliable age technique for adults. Using the changes in morphological features to develop

phases, Iscan, Loth, and Wright (1984, 1985) further developed these into age ranges for

white females and white males. The first four phases developed for either white females
or white males can be used with late teens and young adults. For white females, phase
one begins at age 14, phase two encompasses 16 to 20 year olds, phase three represents
20 to 24 year olds, and phase four stretches fi'om 24 to 40 years old. The results of this
study show rapid changes in the early phases that taper off around 30 years old. In the
study for white males, the findings are only slightly different and the rapid changes are
still seen most often in the first four phases. For white males, phase one represents 17 to
18 year olds, phase two characterizes 18 to 25 years of age, phase three represents 19 to
33 year olds, and phase four is observed in 22 to 35 year olds. These age ranges, while
not as broad as some techniques, still overlap from the late teens to the late 205.
Radiographic vs. Anthroposcopic Techniques

Prior to extensive research on human skeletal remains, radiology was a primary
source of gathering information about human bone growth. The most notable early
studies on vertebral development are those performed by means of roentgenology in
which living subjects of known age are studied and compared. Flecker (1942) provides
an overview of the timing and sequence of ossification centers similar to that of
Stevenson (1924). However, Stevenson studied dry human remains, whereas Flecker
uses the roentgenographic method. Flecker’s research discusses the influence to the
timing of ossification centers of outside factors, such as health and endocrine factors. For
each sex, Flecker provides the ages of the youngest and oldest individuals with no
epiphyseal union, with at least half of the ossification centers present, and with complete
union. F lecker does not differentiate between beginning union and nearly complete

union; he only differentiates between fusion and non-fusion. In reference to the vertebral

column, Flecker notes the lack of roentgenographic study in this area. The only mention
of the fusion of the epiphyses of the vertebral bodies is noted on the lower thoracic and
lumbar vertebrae. These epiphyses were observed in two individuals aged 12 years and 5
months and 13 years and 5 months.

Girdany and Golden (1952) also present a study on ossification centers based on
roentgenograms. The authors report that the annular epiphyses of the vertebrae appear
around puberty (defined as 16 years), but could appear by seven years of age. There is
complete fusion of all of the centers of the vertebrae by 25 years of age. Girdany and
Golden make special note of the sex difference in the time of appearance of ossification
centers stating, “The time of appearance of centers of ossification differs considerably in
the two sexes, and even in the same sex normal individual variation is great. An
evaluation of the ossification age of any individual must take into account these
variables” (923). Girdany and Golden do not discuss the progress of union between
appearance and complete fusion because the progress of union on bones, such as the
vertebrae, is not visible on radiographs.

Bick and Copel (1958) provide a radiographic and histologic study on the annular
ring epiphyses of the vertebrae. The authors conclude that the epiphysis begins to fuse to
the centrum around 17 years of age. By 18 years of age the fusion is apparently complete
and at 20 years, the epiphyseal ring cannot be identified histologically. Hindman and
Poole’s (1970) research concurs with the age estimations of Girdany and Golden (1952)
in that the epiphyses for the vertebral bodies appear around 16 years of age and fuse at
approximately 25 years. However, the authors note several cases in which the vertebral

body epiphyses are visible radiographically as early as two years of age. Although these

studies are usefiil in observing the normal variation in time of appearance and fusion of
the vertebral ring epiphyses, the radiographs cannot show the progress of union as the
bone matures.

An evaluation of the studies based solely on radiographs show that x-rays are not
detailed enough to show the progress of union. Radiographs are good for observing
primary centers of ossification, but observing the progress of union is best accomplished
by anthroposcopy. Utilizing anthroposcopic methods allows for detailed observations not
obscured by features on a radiograph. Observations about how far along union has
progressed is important in understanding the amount of time it takes for complete fusion
to occur and any pattern in how the fusion occurs. Noting the progress of union also
enables the researcher to accurately document what occurs between the appearances of
the epiphyses and when the union is complete. Therefore, although radiographs could
have provided a larger and more modern sample, dry bone of known individuals from a

skeletal collection were used despite the limitation in sample size and ages.

10

Chapter 3

Vertebral Ossification

Primary Centers of Ossification

Bone development, or ossification, follows a predictable pattern in humans.
There are two modes of ossification: intramembranous and endochondral (White, 2005).
The vertebral column is formed through endochondral ossification, which occurs when a
cartilage precursor or model is present before the bone is calcified and hardened (White,
2005). Although ossification begins before birth, it is not complete until many years
afterward. The ossification centers that appear before birth are referred to as primary
centers of ossification, while the ossification centers that appear after birth are known as
secondary centers of ossification (Scheuer and Black, 2004). The vertebrae begin as
cartilage models penetrated by a plethora of blood vessels. The marks of these blood
vessels are visible on immature vertebrae as the billowed appearance on the superior and
inferior surfaces of the juvenile centrum and occasionally the adult vertebral body
(Scheuer and Black, 2004). The vertebrae grow both interstitially and appositionally.
There are seven cervical vertebrae, the first two of which are unique, even from each
other. The first cervical vertebra is formed by three primary ossification centers, the
second cervical vertebra is formed by four primary ossification centers, and the last five
cervical vertebrae are formed by three ossification centers (Scheuer and Black, 2004).
Unlike the thoracic and lumbar regions of the vertebrae, the primary ossification centers
of the neural arches appear before the ossification centers for the centra in the cervical

vertebrae (Scheuer and Black, 2000). Refer to Figures 2 and 3, on pages 39 and 40,

ll

which display the general anatomical characteristics of C2 and a typical vertebra (C3-
C7).

The first cervical vertebra, or the atlas, is formed by three primary ossification
centers: one anterior arch and two neural arches, or lateral masses (Scheuer and Black,
2004). These neural arches later form the posterior arch. Other than an increase in size,
there is relatively little morphological change in the atlas during the first year after birth.
The two neural arches usually appear around the seventh fetal week. The neural arches
fuse together between ages three and five (Scheuer and Black, 2004). The anterior arch
is visible around one year of age. The anterior arch fuses with the neural arches between
five and seven years of age (Scheuer and Black, 2004). The completion of the transverse
foramina of the transverse process occurs around three to four years. By four to six years
of age the atlas has grown to its final adult size (Scheuer and Black, 2004).

The second cervical vertebra, or the axis, is formed by five primary ossification
centers: two neural arches, one centrum, and one for each half of the dens (Scheuer and
Black, 2004). The dens, or odontoid process, a unique feature of the axis, actually forms
from two separate ossification centers that appear between four and six fetal months and
fuse around seven or eight fetal months or by birth (Scheuer and Black, 2004). In
juveniles, the dens appears forked at the apex until the fusion of the secondary epiphyses
at around twelve years of age (Scheuer and Black, 2004). The neural arches appear
between seven and eight fetal weeks and fuse together between two and four years. The
ossification center for the centrum appears around four or five fetal months. The centrum
fuses with the dens at the dentocentral junction and with the neural arches at the

neurocentral junction between the ages of four to six years (Scheuer and Black, 2004).

12

The dentocentral junction fuses with the paired neurocentral junctions between three and
six years of age. A fusion line at this junction site may remain, but usually disappears by
age nine or ten. The completion of the transverse foramina occurs between the ages of
three and five years (Scheuer and Black, 2004).

Five cervical vertebrae, C3-C7, are each formed by three primary ossification
sites: one centrum and two neural arches (Scheuer and Black, 2004). The appearance of
the neural arches occurs first and commences at the end of the second fetal month. The
ossification sites for the centra appear in the third and fourth fetal months beginning with
C7 and progressing cranially until the last centra appear in C3 (Scheuer and Black, 2004).
The neural arches usually fuse around two or three years of age. The centrum fuses with
the neural arch at the neurocentral junction between three and four years of age. The
transverse foramina are complete around three or four years of age (Scheuer and Black,
2004). Refer to Figures 4 and 5 on page 41 for a representation of the primary
ossification centers of C2 and a typical cervical vertebra.

Secondary Centers of Ossification

In general, each cervical vertebra has five secondary centers of ossification, or
epiphyses. Three of the secondary ossification centers are found on each tip of the two
transverse processes and the tip of the spine. The last two secondary ossification centers,
found in all vertebrae except Cl and the superior surface of C2, are flat, ring-like
epiphyses, or growth plates, that encompass both the superior and inferior surfaces of the
vertebral centrum (Scheuer and Black, 2004). Many of the research studies and anatomy

textbooks state that the secondary epiphyses of the vertebrae fuse during early or young

13

adulthood. However, the term “young adulthood” is subject to varying interpretation and
can many times be defined differently or not at all depending on the source.

The secondary ossification centers for C3-C7 that appear later in childhood,
including the tips of the transverse processes and spinous process, and on both the
superior and inferior surfaces of the centrum (Scheuer and Black, 2004). The epiphyses
of the transverse and spinous processes may persist until early in the third decade of life.
The epiphyses on the superior and inferior surfaces of the centrum fuse in early
adulthood. This is important because it extends the time period in which epiphyseal
union can be used as an aging method. Since these are later fusing epiphyses, forensic
anthropologists can utilize this method for narrowing age ranges to within early to middle
20$ rather than 20 plus years. Figure 6 on page 42 displays a representation of the

secondary centers of ossification of a typical cervical vertebra.

l4

Chapter 4

Vertebral Ring Epiphyseal Union

Past studies of vertebral ring epiphyseal union from skeletal remains include
Stevenson (1924), McKem and Stewart (1957), Buikstra (1980, 1984), Steele and
Bramblett (1988), and Albert and Maples (1995). What is known from these studies
concerning vertebral ring epiphyseal union is presented below.

In 1924, Stevenson pioneered an in-depth study into the order of epiphyseal union
and the correlation of age to this order. Stevenson’s sample consisted of 128 individuals
of known age between 15 and 28 years. Stevenson established four distinct phases of
epiphyseal unionf The first stage was that of no union, characterized by a centrum with
rough edges and a billowy surface. The second stage is that of beginning union,
characterized by the change in the space between the epiphyses and the centra being
replaced by a fine line, an increase in new bone deposition on the once billowed surface,
and a smoothing out of the rough edges. The third stage is that of recent union and is
characterized solely by the retention of a line of demarcation that can persist into the
fourth stage as an epiphyseal scar. The fourth stage is that of complete union with the
sole remaining characteristic at this point being the epiphyseal scar. Stevenson applies
these stages of union to 28 epiphyses on 10 bones in order to draw a conclusion of a
sequence of the union of epiphyses in the human body. Although Stevenson did not
include any vertebrae in his study, the general results and conclusions regarding
epiphyseal unions are significant. Stevenson notes that the period between 15 and 20
years is distinguished as the period of epiphyseal union. Also, Stevenson’s results depict

a fusion curve in which relatively few epiphyses begin the process of uniting prior to the

15

age of 18 years. Throughout his study, Stevenson stresses that “At the outset it may be
stated that the determination of age depends not so much upon the condition of any one
or two epiphyses as upon the general condition of all epiphyses of the body” (1924; 82).
Anatomy textbooks have generally stated that the epiphyseal ring of the vertebral
body fuses by the age of 25 years. McKem and Stewart were the first to examine the
progression of union fi'om epiphyseal early attachment to ages of final fusion. McKem
and Stewart’s 1957 publication encompassed a series of aging methods for young
American males in response to the need for establishing positive identifications during
the Korean War. McKem and Stewart studied skeletal indicators of age in 259 racially
mixed males between the ages of 17 and 25 years. McKern and Stewart emphasized that
the progression of union of all of the epiphyses of the vertebrae are important in skeletal
aging. For the superior and inferior surfaces of the thoracic vertebrae, McKem and
Stewart developed a scoring method using five stages (0-4) representative of the progress
of union. McKem and Stewart reported that stages 2 and 3 appear most commonly
between 19 and 21 years of age. The last stage, stage 4, is reportedly always present by
24 years. McKem and Stewart found no significant difference in the rate of union
between superior or inferior rings. Regarding the sequence of epiphyseal union across
various thoracic vertebrae, a consistent delay in union was found on the centrum surfaces
between T2 and T7, especially T4 and T5, until the age of 24 years when compared to
other thoracic vertebrae. By the age of 20 years, complete union was seen exclusively in
T1 and T8-T12. Complete union in T2-T7 was achieved during the ages of 20-24 years.
McKem and Stewart described the appearance of the superior and inferior surfaces of the

vertebral centrum and developed a scoring method to estimate the amount of epiphyseal

l6

I union. Five stages (0-4) were developed to score the superior and inferior surface of each
vertebral centrum in the sample. These stages represented no union, beginning, active,
recent, and complete union respectively. One of the observations McKern and Stewart
noted was the billowing or striations that appeared on the immature surfaces of the
centrum. According to the study, over time, the striations disappear and the surfaces
become pitted and irregular. However, McKem and Stewart emphasize the persistence of
the striations with age and ultimately state that human variation hinders the results of this
study as assisting in age identification

Whereas McKem and Stewart studied thoracic vertebrae, Buikstra, et al. (1980,
1984) focused on cervical vertebrae. During a case that called into question whether or
not two vertebrae, a third and fourth cervical vertebra, were of the same individual, a
black female. To answer this question, a study was conducted using a small sample of
black females between 17 and 25 years from the Terry Collection housed at the
Smithsonian Institute in Washington DC. Epiphyseal ring union was observed for the
second, third, and fourth cervical vertebrae. Epiphyses of each superior and inferior
surface, as well as the posterior (dorsal) and anterior (ventral) halves, were scored based
on McKem and Stewart’s (1957) five stage scoring method where stage 0 represented no
union and stage 4 represented complete fusion. Of several results, Buikstra found that the
epiphyseal rings are generally fused to the centra by the age of 25 years. Buikstra stated
that “By age 23 epiphyseal rings for most upper cervical vertebrae should show at least
Stage 3 fusion” (1984, 131). The results also suggest that an advanced stage of

maturation is found at any given age on the cervical vertebrae that are closer to the skull

l7

rather than that of the lower cervical vertebrae. Also, in general, the ventral half appears
more advanced in maturation than the dorsal aspect.

In addition to McKem and Stewart and Buikstra, ct al., Steele and Bramblett, in
their textbook The Anatomy and Biology of the Human Skeleton, the grth and
development of the vertebral column is described. The authors reported that the
epiphyses of the cervical vertebral centra of males appear to begin fusion around the age
of 17 years with fusion being complete around 25 years of age. Steele and Bramblett
state that the sequence of vertebral ring fusion of epiphyses generally proceeds from the
two ends (cranial and caudal) toward the middle (thoracic) (Steele and Bramblett, 1988).
The cervical vertebrae are further broken down into the atlas (Cl), axis (C2), and the true
cervical vertebrae (C3-C7). The axis is described as the strongest of the cervical
vertebrae because of the combination of the dens and the body, and it carries a unique
statement by the authors denoting that the inferior surface of the axis unites by young
adulthood, qualified as 19-20 years. There are two spans of time differentiated by Steele
and Bramblett (1988) that are important in the fusion of the vertebral ring epiphyses. The
first is adolescence, spanning ages 13 to 24 years, and second is young adulthood, {tom
25 to 49 years. In adolescence, the vertebral ring epiphyses appear and begin to fuse to
the primary centers of ossification. By the end of adolescence, the vertebral ring
epiphyses are completely firsed to the vertebral bodies. Young adulthood is characterized
by the complete fusion of the epiphyseal rings of the vertebral bodies, typically occurring
around the age of 25 years. Steele and Bramblett report that during early adulthood, the
vertebral bodies exhibit radiating striae, but as adulthood progresses and bone is

deposited over the surface, the striae are gradually obliterated. In the later stages of

18

adulthood and senescence, the striae become completely obliterated. Also, the distinction
between the epiphyseal rings and the surface of the vertebral bodies will disappear
(Steele and Bramblett, 1988). That the ages correlating with these stages of young, later,
and old adulthood are not defined specifically prohibits any informative comparison to
the conclusions of other studies.

One study that focused on the stages of progress of union of the vertebral ring
epiphyses was Albert and Maples (1995), who studied the stages of epiphyseal union of
the vertebral centra of the thoracic and first two lumbar vertebrae. This study took
McKem and Stewart’s stages one step further to explore sex and race differences in
epiphyseal union, and to see if any secular changes might have occurred since it was
about 40 years since McKem and Stewart (1957) published their results. While McKem
and Stewart’s sample consisted only of males, Albert and Maples included females into
their sample. Also, Albert and Maples were able to expand the investigated ages to
earlier than 17 and later than 25 to explore how early the epiphyseal ring union begins
and if it extends beyond 25 year olds. Albert and Maples collected vertebrae from 55
individuals during autopsy for a sample that included American males and females, of
Afiican American and European ancestry. McKem and Stewart’s original five stages
were modified into four stages to better account for the last signs of union. This change
enabled the stages to have early and late phases to better represent the progression of the
epiphyseal union. Albert and Maples found that McKem and Stewart’s stages did not
account for the time fi'ame in which the skeletal changes seem to occur. For example,
beginning union and progressing union were placed in the same stage (Stage 1), but

defined as an early and late phase because this skeletal modification occurs over the

19

period of only a few months. Progression slows toward the completion of union and can
continue for several years. The results showed that for the earliest or youngest age
complete union was 24 to 25 years old, although the youngest to show complete union of
all epiphyses was 18 years old. Also, Albert and Maples found no statistically significant
sex or race differences in the timing or rate of the epiphyseal union. The first two lumbar
vertebrae also followed a rate of union comparable to the thoracic vertebrae. In addition,
the superior and inferior surfaces of the vertebrae showed no significant differences in the
sequence of union. Although occasionally one surface of a vertebra either the superior or
inferior epiphyses would show a more advanced phase of union than the other, the
differences were not systematic. The superior and inferior epiphyses generally
demonstrated the same stage of union.

As is evident from the above literature review, there have been no rigorous efforts
to explore skeletal maturation of the cervical vertebral centra. Buikstra, et al.’s (1980,
1984) severed skull study was an attempt to apply to the cervical vertebrae McKem and
Stewart’s thoracic vertebral ring epiphyseal union aging method. However, this was a
case that required aging only two cervical vertebrae, and was not an in-depth research
study. Therefore, Buikstra’s case did not involve comparisons of maturation among all
cervical vertebral ring epiphyses or between cervical and thoracic and lumbar vertebral
ring epiphyses. Data on cervical vertebral ring epiphyseal union can lead to a better
understanding of the pattern of vertebral union in general. This in turn would aid skeletal
age estimation efforts in that (1) it would help narrow what would otherwise be a broad
age range, (2) could be used to corroborate findings from other skeletal sites, and (3) can

be helpful in the absence of other key skeletal indicators of age.

20

Chapter 5
Methods

Sample

The cervical vertebrae of 77 individuals of known age, sex, and ancestry between
the ages of 12 and 27 years were studied. The sample consisted of 11 white females, 27
black females, 15 white males, and 24 black males aged 12 to 27 years at death from the
Harnann-Todd Osteological Collection housed in the Physical Anthropology section of
the Cleveland Museum of Natural History in Cleveland, Ohio. Epiphyseal union data
were collected from the inferior surface of the centrum of C2, and from the superior and
inferior surfaces of the centrum of C3 through C7. The first cervical vertebra (Cl) has no

centrum, and the superior surface of C2 does not have a ring epiphysis, so they were

 

 

 

excluded from this study.
Table 1 — Sample Demographics.
Blacks Whites
Males 24 l 5
Females 27 ll

 

 

 

 

 

Scoring the Progress of Vertebral Ring Union

Epiphyseal union is a continuous process; however, the points at which key
changes occur can be represented by using a basic scoring system. The scoring method
utilized in this study was based on the method Albert and Maples (1995) modified for
their study of the thoracic and first two lumbar vertebrae. The stages are described

below.

21

Stage 0 — This stage is characterized by no union, where there is no attachment of
the ring epiphysis of the centrum. The superior and inferior surfaces of the centrum may
be billowed or striated due to the radiating vascular channels stemming from the anterior
and posterior central perforating arteries. The edges of the centrum are dull and rounded
until they become sharper right before union begins. The surface of the centrum is rough
and usually has a bare appearance. There is clearly no evidence of epiphyseal ring
adhesion on the centrum (Albert and Maples, 1995). (See Figures 9, 10, and 11)

Stage 1 — This stage indicates beginning union of the epiphysis and the vertebral
centrum. In the early phase of this stage, the epiphyseal ring is attached in only a small
area to the vertebral centrum. The epiphyseal ring is described as thin and fragile. The
late phase is represented by progressing union. At this point, the epiphysis is more
solidly attached to the centrum and has less open spaces, but in less than half of the
centrum. Essentially, more than half of the area of union is open and unfused (Albert and
Maples, 1995). (See Figures 12, 13, and 14)

Stage 2 — This stage feature almost complete union in the early phase and recently
complete union in the late phase. In the early phase, where there is almost complete
union, the epiphysis has united with more than 50% of the vertebral centrum surface.
Therefore, there is a smaller space between the epiphysis and vertebral centrum. In some '
areas where union has occurred, a distinct, indented line or groove appears between the
epiphysis and the centrum. In the late phase, where there is recent union, there are no
spaces left and there is a distinct and uniform line or groove between the epiphysis and

the centrum (Albert and Maples, 1995). (See Figures 15, 16, and 17)

22

Stage 3 — This stage represents a completely mature vertebral body, where the
epiphysis is fully fused to the centrum and the vertebra and appears as one piece. Also,
the line or groove seen in previous stages that marks the epiphyses from the centrum is
completely obliterated. However, a scar may persist where the line demarcating the
epiphysis fiom the centrum has remained. A scar is described as a smooth, shallow
depression, whereas the line seen in the recent union phase is wider, deeper, rougher, and
coarser (Albert and Maples, 1995). (See Figures 18, 19, and 20)

Analyses

Both statistical and observational analyses were conducted. Statistical analyses
were performed to calculate the mean value stage for each individual to correlate the
known age and assessed stage. Statistical analyses were also carried out to calculate the
mean stage for each individual in the sample and correlating this number with the known
age to determine the reliability of the method.

Observations beyond classifying each vertebra to an epiphyseal stage were
described. The youngest and oldest individuals to exhibit each stage of epiphyseal union
were noted between the sexes to show progression of growth and variation. Patterns in
the sequencing of the epiphyseal union along the cervical vertebrae were observed, as
well as any differences in the stages of the superior or inferior surface of any given
vertebra. The sequence of epiphyseal union throughout the cervical vertebrae and other
significant patterns are crucial to understanding the growth and development of not only

the cervical vertebrae, but the entire vertebral column.

23

Chapter 6

EMS.
Statistical Analyses

Statistical analyses were performed on data collected on 77 individuals. Eleven
surfaces, superior and inferior aspects of five centra (C3-C7), as well as inferior C2, were '
observed. Of the 77 individuals, five individuals had vertebral epiphyses omitted because
a particular vertebra was missing, too damaged, or fused to a neighboring vertebra.

These individuals were not removed from the study, but less than 11 surfaces were
appropriately scored. Because the study focused on the maturation of the cervical
vertebra, the stages of each surface are not necessarily the same for a given individual
since growth is in progress. A way to simplify each individual represented by 11
numbers was needed and therefore statistical analyses were performed.

Since there were as many as 11 variables (stages of union) recorded for each
individual in the sample, mean values representing the overall progress of union were
calculated. The mean represents the average stage number for each individual in the
sample. Mean epiphyseal union values for individuals in the overall sample were
correlated with their known age at death. Further, mean values of females and males
were correlated with known age separately to test for sex differences. Therefore, the
correlation of means and the age of 38 females were calculated and subsequently for the
39 males, and for 51 blacks and 26 whites.

Also worthy of consideration were calculations of the maximum number and
mode of epiphyseal union for each individual in the sample. The maximum number is the

most advanced stage recorded on any cervical vertebrae for each individual in the sample

24

representing the most advanced progress in each individual. The mode is the stage most
frequently observed on the cervical vertebrae of each individual in the sample
representing the overall progress of the cervical vertebrae as a whole. These calculations
are encompassed within the results of the observational analyses.

The maximum number, while it may be a sign of stage progression or
development, and the mode, while it shows the stage of greatest frequency, fails to
represent the individual’s stage as a whole. The average, or mean, for each individual
allows all stages to be accounted for equally. Also, the mean is used in this analysis due
partly to its usage in the original Albert and Maples (1995) thoracic and first two lumbar
vertebrae study.

An overall correlation of .781 was found between mean values computed from the
stages of epiphyseal ring union of all vertebrae for each individual in the study, and
known age at death, for the overall pooled sample. This was calculated using the mean
value stage for each individual in the study. The calculations indicate a positive
correlation meaning that as the mean stage increases, age increases. Correlations were
also calculated separately for males and females. The correlation between mean stage of
vertebral ring epiphyseal union and age for females was higher at .854 than males who
showed a correlation of .688. The correlation suggests that this scoring method for
vertebral ring epiphyseal union is stronger and more accurate for females than males.
Refer to Table 2 below for a summary of the correlation between the mean stage value
and the known age of an individual. Scatter plot graphs depicting the correlations
between mean stage of vertebral ring epiphyseal union and age listed in Table 2 can be

referenced on pages 43 and 44 (Figures 7 and 8).

25

Table 2 — Statistical Analyses: Correlation Results.

 

 

 

 

 

Correlations R Significance
Overall (n=77) .78 l <.000
Female (n=3 8) .854 <.000

Male (n=39) .688 <.000

 

 

 

 

Observational Analyses

While results of the correlation analyses were informative, observational results
of the progression of union — from the time of onset to the time of complete union —
provided information beyond what statistical analyses was able to reveal. Results are
presented for females and males, by stage of union. The sample was not broken down
into ancestry because the diversity in the sample was too small and there were no
differences found. Observations for the early and late phases of each stage are discussed
below, as well as any results based on sequencing and patterns.

Upon tabulation of the collected data, several key observations were made and are
described below. Refer to Table 3 for a summary of the observations for stages of
vertebral ring epiphyseal union. Also, refer to Tables 4 and 5 on pages 54 — 57 for
complete scoring data for each individual in the sample.

m
Stage 0

The early phase of stage 0 is characterized by no attachment of epiphyseal rings in

any vertebrae. The youngest female to show this phase was 12 years old. The youngest

male to exhibit this early phase was 17 years old.

26

The late phase of stage 0 is characterized by the oldest individual to show no
union in any vertebrae. The oldest individual to show non union on any vertebrae is 18
years in females (C5, superior; C6, superior; C7, superior) and 19 years in males (in all
vertebrae).
Stage 1

The early phase of stage 1 is beginning union. There are two females who are the
youngest to show beginning union on any vertebrae at the age of 12 years (the first
female: C3, superior and inferior; C4, superior and inferior; the second female: C3,
inferior; C4, superior and inferior). The youngest male to show beginning union is 16
years of age (C2, inferior; C7, inferior).

The oldest female to show beginning union on any vertebrae is 23 years of age
(C5, superior; C6, superior; C7, superior). There are two males who are the oldest to
exhibit Stage 1 on any vertebrae at the age of 21 years (the first male: C2, inferior; C3,
superior and inferior; C4, inferior; C6, superior and inferior; C7, superior and inferior; the
second male: C4, inferior; C5, inferior; C7, inferior).
Stage 2

The early phase of stage 2 is almost complete union. There are two individuals
who are the youngest females to exhibit almost complete union at the age of 16 years (the
first female: C3, superior; the second female: C2, inferior; C3, inferior). There are three
males at the age of 18 years who are the youngest to show almost complete union on any
of the vertebrae (the first male: C2, inferior; the second male: C2, inferior; C3, superior
and inferior; C4, superior; C5, inferior; the third male: C3, inferior; C4, inferior; C6,

inferior; C7, inferior).

27

The late phase of stage 2 is recent union. The oldest individuals to exhibit recent
union on any vertebrae are 27 years of age for both males and females, in which there are
three males (all three males: in all vertebrae) and three females (the first female: C7,
inferior; the second female: in all vertebrae; the third female: in all vertebrae except C2,
inferior).

Stage 3

The early phase of stage 3 is complete union in any vertebrae. The youngest
female to show complete union on any vertebrae is 19 years of age (C4, superior). The
youngest male to show Stage 3 on any vertebrae is 18 years of age (C2, inferior; C3,
superior; C4, superior; C5, superior and inferior; C6, superior; C7, superior).

This phase of Stage 3 is usually described as the youngest individuals to show
complete union of the epiphyseal rings in all of the vertebrae. However, none of the

individuals in the study exhibit complete union in all of the vertebrae.

28

Table 3 — Summary Observations of Vertebral Ring Epiphyseal Union Stages.

 

 

 

 

 

 

Females Males

Earliest Stage 0 12 years 17 years
Latest Stage 0 18 years 19 years
Earliest Stage 1 12 years 16 years
Latest Stage 1 23 years 21 years
Earliest Stage 2 16 years 18 years
Latest Stage 2 27 years 27 years
Earliest Stage 3 19 years 18 years
Latest Stage 3' Unavailable Unavailable

 

 

 

 

Em

Observational analyses shows no significant differences regarding the sequence of
union between the superior and inferior ring epiphyses for either a particular vertebra or
among any vertebrae for a given individual. Out of 385 vertebrae observed, only 71
vertebrae or 18% revealed different stages for either the superior or inferior surfaces.
The second cervical vertebrae were excluded from this analysis due to the lack of a
superior surface. Among C3-C7 there is a relatively even distribution of the number of
vertebrae (between 12 and 17) that exhibit different stages on either the superior or
inferior surface of one vertebra. Of the 71 vertebrae that showed different stages, 46
vertebrae exhibited a more advanced stage on the superior surface than on the inferior
surface while only 25 showed a more advanced stage on the inferior surface than on the
superior surface. In general, the superior and inferior ring epiphyses stage only differs

within one stage. No particular sequences of stages (stage 0 — stage 1; stage 1 — stage 2;

29

stage 2 — stage 3) were over-represented to suggest a significant delay between any
specific stage. However, there was one individual, 16 years of age, which exhibited a
stage 2 on the superior surface and stage 0 on the inferior surface. This is the only

anomalous vertebra found in this study.

30

Chapter 7

Discussion

Results of this study of the vertebral ring epiphyseal union of cervical vertebrae
are significant, especially when compared with what is also known about the thoracic and
first two lumbar vertebral ring epiphyseal union. The observations and stages recorded in
this study show that although McKem and Stewart (1957) only look at the thoracic
vertebrae of males from age 17 to 25, when the sample age is expanded in either
direction, more information can be gleaned about the maturation of the vertebrae in
regards to the vertebral ring epiphyseal union. Not only was the age of the sample
expanded, but sex and ancestry were also evaluated. This variation was unavailable in
McKem and Stewart’s sample.

The results found in this study and the original Albert and Maples (1995) results
are remarkably close. Albert and Maples (1995) report an overall correlation of 52
individuals at .78 (.7754). Likewise an overall correlation of .78 (.781) was found for the
overall combined sample between mean values from the stages of epiphyseal ring union
of all vertebrae for each individual in this study, and known age at death. The correlation
results of this study were consistent with findings from the thoracic and first two lumbar
vertebrae, which demonstrates the efficacy of this aging method as well as its
applicability to the cervical vertebrae (McKem and Stewart, 1957; Albert and Maples,
1995).

Although the demographics of this study did not allow for sufficient analysis of
ancestral differences, sex differences were evaluated. Sex differences were found based

on the calculated correlations between the mean stage of vertebral ring epiphyseal union

31

and age. There are 38 females and 39 males in the sample allowing for an equal
comparison between sexes. Females were found to have a higher correlation at .854,
while males in this sample show a correlation of .688. The higher correlation for females
suggests a higher reliability and effectiveness in the method when used to evaluate
females. However, both correlations are significant and suggest an overall efficacy for
both sexes.

While Albert and Maples (1995) reported the youngest age to show beginning
union on any vertebrae as 14 years in females and 16 years, 4 months in males, beginning
epiphyseal union was found in the cervical vertebrae of this sample as early as 12 years
of age. This supports the notion that epiphyseal union initiates at either end of the
vertebral column and progresses toward the middle (Steele and Bramblett, 1988).
However, at this time, only the cervical, thoracic, and first two lumbar vertebrae have
been investigated. Further research would be necessary on the lower lumbar vertebrae or
the entire vertebral column to better corroborate these findings.

Secular changes in skeletal growth and maturation were reviewed recently by
Schaefer and Black (2005). The authors compared the rate of epiphyseal union on ten
skeletal sites between a Bosnian population from the 19905 and the rates previously
reported by McKem and Stewart from an American population in the 19408 and 19503.
Schaefer and Black (2005) reported some populational differences at the time of
complete union of some of the epiphyses. Although McKem and Stewart’s (1957)
sample, Albert and Maples’ (1995) sample, and the sample from the Harnann-Todd
Osteological Collection used for this study are all from the American population, the

sample for each study originate in different time periods. The Hamann-Todd

32

Osteological Collection was acquired over the course of many years between the 19003
and 19203, McKem and Stewart’s sample was acquired from the 19403 and 19503, and
Albert and Maples collected their samples in the 19903. Due to the consistency in the
results that can be compared in this study, it can be noted that although there were secular
changes between populations, there were no secular changes observed within the
American population spanning through the 20th century with regards to vertebral ring

epiphyseal union.

33

Chapter 8

Conclusion

Aging techniques in forensic anthropology inherently possess several limitations.
The initial downfall is the challenge presented by human variation and its effect on the
progression of age on the bone. Human variation produces age ranges that can be broad,
spanning several decades at times and decreasing the utility of the method. So the aim is
to continue research efforts into revealing, which, if any, skeletal sites show less variation
and therefore, lead to narrower estimated ranges which result in greater utility, especially
in forensic cases. Studies in the area of vertebral aging are important for the field of
forensic anthropology because it can provide information that can help distinguish late
teens to early 203 and from early 203 to mid 203. Current methods of aging provide a
wide age range such as the methods developed for the pubic symphysis and the ribs, but
by using the vertebral aging method in combination with other methods of aging, the age
range can be narrowed down. Essentially, vertebral ring epiphyseal union aids skeletal
age estimation by narrowing otherwise broad age ranges, corroborating findings from
other skeletal sites, and using the method in the absence of other key skeletal indicators
ofage.

The results of this study indicate that the same staging methods developed by
Albert and Maples (1995) for the thoracic and first two lumbar vertebrae can be applied
to the cervical vertebrae. The similarity between the correlations found in the original
Albert and Maples (1995) study and those found in this study show a consistency in the
scoring method throughout the vertebral column, its reliability in correlation with age,

and its repeatability among different observers. As the results have shown a consistency

34

in age and vertebral ring epiphyseal union, it is important to note that the data collected
can be used in both a forensic and archaeological setting.

Future research could focus on scoring every surface of the centrum on the entire
vertebral column of an individual and comparing that correlation with the ones found
here and for the thoracic and first two lumbar vertebrae. Also, although the sample size
in this study was sufficient for statistical analyses, there were a low number of whites,
especially white females, available for this study. Further research utilizing a comparable
sample size of whites and blacks, and males and females could yield important results
regarding sex and race differences. As is evident by the overview of previous research in
the area of vertebral ring epiphyseal union, there is a need to further explore the
maturation of the vertebral column more thoroughly, to not only continue to utilize this
information for age estimation, but to better understand the general maturation of the
vertebral column and its significance to the overall maturation of the entire skeleton.

It is the responsibility of a forensic anthropologist to utilize as many parts of the
human skeleton as possible to appropriately acquire an estimation of age. The vertebral
column as a whole has largely been ignored. While many other aspects of the skeleton
can assist in developing an age estimation, it is important that all aspects of the skeleton
be explored for its potential in not only age, but sex, ancestry, stature, pathology, and any
other information it could potentially yield. Exploring the potential of the entire skeleton
can be especially important in a few specific situations. We have the opportunity as a
global society to be prepared for mass disaster situations like we have never been able to
prepare before. Part of that preparation includes adjusting every method necessary to,

when the time comes, be prepared to handle, analyze, and identify human remains. In

35

cases where bodies are commingled, the ability to associate the remains with each other
is paramount in ultimately making a positive identification. While the field of forensic
anthropology, skeletal analysis, and human identification is not perfect and never will be,
the world’s tragedies continue and the best methods and techniques we can provide is the

least we can do as human beings and responsible forensic science professionals.

36

APPENDIX A

37

Figure l — Cervical Aspect of the Vertebral Column

 

38

C1

C2

C3

C4

C5

C6

C7

Figure 2 — Characteristics of the Second Cervical Vertebra

Anterior Articular Facet
Dens
\

 
 
  
   
  
   

Superior

Articular Facet Interarticular Part

Inferior Body Transverse Process
Articular Facet

Axis (C2): Anterior View
Dens Posterior Articular Facet

Superior
Articular Facet

Interarticular Part ransverse Process

Spinous Process
Inferior Articular Facet

Axis (C2): Posterosuperior View

(Netter, 2003)

39

Figure 3 — Characteristics of a Typical Cervical Vertebra (C3-C7)

Anterior Tubercle Body Transverse Process
Groove for Spinal Nerve

  

Posterior Transverse Forarnen
Tubercle
Pedicle

Superior Articular Facet

Inferior Articular Process
\ Vertebral Forarnen
- Spinous Process

4"1 Cervical Vertebra: Superior View

Transverse Process Body

Groove for Spinal Nerve Anterior Tubercle

    
  
 
    
 

Transverse Forarnen Posterior Tubercle

Pedicle 7‘

Superior Articular Facet -
Inferior Articular Facet ___.'
Vertebral Forarnen
Spinous

Process

7’" Cervical Vertebra: Superior View

(Netter, 2003)

40

Figure 4 — Primary Centers of Ossification of the Second Cervical Vertebra

 
   

F approx. yr 12 ——_—
F by birth \.
F yrs 3-4
F yrs 4-6 ‘

F yrs 4-6

 

 

A mths 4-5 (prenatal)

A wks 7-8 (prenatal)

F yrs 3-4 .5

Figure 5 — Primary Centers of Ossification of a Typical Cervical Vertebra

[/ererpuberty
Fyr2

 

A mths 2-3 (prenatal)

A mths 3-4 (prenatal)

 

A - Time of Appearance
F — Time of Fusion

41

Figure 6 — Secondary Centers of Ossification of a Typical Cervical Vertebra

Spinous Process \\

Transverse
Process

Superior Ring Epiphysis
of the Centrum \

 
   

 

. - .- Transverse Process
/
a (I. “

  
  

Inferior Ring
Epiphysis of the Centrum

42

Figure 7 — Correlation between Mean Stage of Vertebral Ring

Epiphyseal Union and Age for Females and Males

Correlation Between Mean and Age for Female: and Male:

 

3.000 -‘

2.500 -i

2.000 -'

Mean
i

LOW-i

0.500 '1

0.000 "‘

 

 

 

 

I 1 T— l I
12 14 16 13 20
Age

43

//ue
3‘2“

R Sq Linear = 0.473

P ‘31.] Linear = 0.729

Mean

Figure 8 — Overall Correlation of Mean Stage Vertebral Ring

Epiphyseal Union and Age

Overall Correlation of Means and Age:

 

 

 

 

 

APPENDIX B

45

 

Figure 9 — Example of Stage 0 Vertebral Ring Epiphyseal Union (C7-S)

Images in this thesis are presented in color.

 

Figure 10 — Stage 0 Vertebral Ring Epiphyseal Union (C4-I)

46

 

Figure 11 — Stage 0 Vertebral Ring Epiphyseal Union (C5)

47

 

Figure 12 — Example of Stage 1 Vertebral Ring Epiphyseal Union (C6-I)

 

Figure 13 — Stage 1 Vertebral Ring Epiphyseal Union (C7-I)

48

 

Figure 14 — Stage 1 Vertebral Ring Epiphyseal Union (C6)

49

 

Figure 15 — Example of Stage 2 Vertebral Ring Epiphyseal Union (CS-I)

 

Figure 16 — Stage 2 Vertebral Ring Epiphyseal Union (C3-S)

50

 

Figure 17 — Stage 2 Vertebral Ring Epiphyseal Union with Persistent Line between

Epiphyses and Centrum (C7)

51

 

Figure 18 — Example of Stage 3 Vertebral Ring Epiphyseal Union (C3-I)

 

Figure 19 — Stage 3 Vertebral Ring Epiphyseal Union (C2-I)

52

 

Figure 20 — Stage 3 Vertebral Ring Epiphyseal Union; Full Adult Vertebra (C3)

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62

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