PERIMORTEM AND POSTMORTEM FRACTURE PATTERNS by...
Transcript of PERIMORTEM AND POSTMORTEM FRACTURE PATTERNS by...
PERIMORTEM AND POSTMORTEM FRACTURE PATTERNS
IN DEER FEMORA
by
CATHERINE SUSAN WRIGHT
A THESIS
Submitted in partial fulfillment of the requirements for the degree of Master of Arts
in the Department of Anthropology in the Graduate School of
The University of Alabama
TUSCALOOSA, ALABAMA
2009
Copyright Catherine Susan Wright 2009 ALL RIGHTS RESERVED
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ABSTRACT
A question remains as to whether specific criteria can be used to differentiate perimortem
and postmortem breakage patterns in deer femora. The purpose of this experiment was to
discover if fracture characteristics, such as smooth or rough fracture surfaces, are statistically
correlated with bone condition (old, new) or bone end (proximal, distal). Two experimental
groups were used (postmortem; n = 46; perimortem; n = 41). Dependent variables (DV) were the
presence or absence of (a) right angles, (b) acute angles, (c) jagged edges, (d) curved edges, (e)
smooth bone surfaces, (f) rough bone surfaces, (g) transverse fractures, (h) butterfly fractures, (i)
number of fracture lines, and (j) number of pieces created from the break. Independent variables
(IV) were (a) the condition of the bone (old, new) and (b) end of the bone (proximal, distal). The
study hypothesis was that perimortem fractures would contain more acute than right angles and
more smooth than rough surfaces and that postmortem fractures would contain more right than
acute angles and more rough than smooth surfaces. A significant correlation among variables
may help future researchers to categorize unknown bones.
Bones were fractured using a Dynatup 8250 Drop Weight Impact Test Machine
(DWITM). New bones were tested within 2 days of receipt, and old bones at least 60 days
following receipt. Distal ends were secured in a vice, while proximal ends were placed on a foam
pad. Descriptive statistics, correlational analyses, and analysis of variance tests were conducted,
with an alpha level of p = 0.05 indicating statistical significance (two-tailed). Significant
correlations were observed between bone condition (old, new) and right angles (rho = -.463, p <
.001, old bones tend to exhibit a right angle); acute angles (rho = .415, p < .001, new bones tend
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to exhibit an acute angle); smooth bone surface (rho = .379, p < .001, new bones tend to exhibit a
smooth fracture surface); and rough bone surface (rho = -.420, p < .001, old bones tend to exhibit
a rough fracture surface). Results may be applicable to scientists in the fields of bioarchaeology
and forensic science.
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LIST OF ABBREVIATIONS AND SYMBOLS
df Degrees of freedom: number of values free to vary after certain
restrictions have been placed on the data
f frequency
F Fisher’s F ratio: A ration of two variances
M Mean: the sum of a set of measurements divided by the number of
measurements in the set
p Probability associated with the occurrence under the null hypothesis of a
value as extreme as or more extreme than the observed value
< Less than
= Equal to
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ACKNOWLEDGMENTS
I am pleased to have this opportunity to thank the many colleagues, friends, and
faculty members who have helped me with this research project. I am especially indebted to Dr.
Kathryn Oths, the chairperson of this thesis, for sharing her research expertise and
wisdom regarding research writing, and statistical application. I would also like to thank all of
my committee members, Dr. Sharyn Jones, Dr. Jason Linville, and Dr. Bruce Wheatley for their
invaluable input, inspiring questions, and support of both the thesis and my academic progress. I
would like to thank Dr. Donna Burnett for her assistance in analyzing the statistical data and in
editing the thesis and Wade Rittenberry and Chris Robinson for assistance in editing. I am
especially thankful to Stephie Deitz for the beautiful photographs.
Dr. Alan Eberhardt provided the use of the Dynatup 8250 Drop Weight Impact Test
Machine to conduct the experiment through the Department of Biomedical Engineering at the
University of Alabama at Birmingham. Without his assistance, and that of his laboratory
engineers, this research would not have been possible.
Most of all, I want to thank Dr. Bruce Wheatley of UAB's Anthropology Department for
creating the original methodology for using the drop weight machine to conduct bone breakage
in similar experiments with deer bones. This methodology informed the design of the present
research. I would like to thank Dr. Wheatley's Advanced Physical and Forensic Anthropology
current and former students who, through class assignments, participated in the acquisition and
preparation of the bones for analyses through careful collection, cleaning, and processing.
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Without the diligence of these students in following Dr. Wheatley's methodology, results of Dr.
Wheatley's studies could not be used for comparison with the present study.
Finally, this research would not have been possible without the support of my friends and
fellow graduate students and, of course, my family members, who never stopped encouraging
me.
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CONTENTS
ABSTRACT ............................................................................................................ ii
LIST OF ABBREVIATIONS AND SYMBOLS .................................................. iv
ACKNOWLEDGMENTS .......................................................................................v
LIST OF TABLES ............................................................................................... viii
LIST OF FIGURES ............................................................................................... ix
1. INTRODUCTION ...............................................................................................1
2. LITERATURE REVIEW AND SIGNIFICANCE ..............................................5
3. METHODS ........................................................................................................14
a. Description of Study Sample .............................................................................15
b. Research Design and Procedures .......................................................................16
4. RESULTS ..........................................................................................................21
5. DISCUSSION ....................................................................................................47
6. CONCLUSIONS................................................................................................52
REFERENCES ......................................................................................................55
APPENDIX ............................................................................................................57
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LIST OF TABLES
4.1 Descriptive Statistics for Variables for Bone Characteristics ..........................22
4.2 Frequency and Percentage of Right Angles .....................................................23
4.3 Frequency and Percentage of Acute Angles ....................................................25
4.4 MANOVA Table for Right and Acute Angles ................................................28
4.5 Frequency and Percentages of Jagged Edges ...................................................29
4.6 Frequency and Percentage of Curved Edges ...................................................31
4.7 MANOVA Table for Jagged and Curved Edges .............................................33
4.8 Frequency and Percentage of Rough Surfaces .................................................35
4.9 Frequency and Percentage of Smooth Surfaces ...............................................37
4.10 MANOVA Table for Smooth and Rough Surfaces .......................................39
4.11 Frequency and Percentages of Transverse Fractures .....................................40
4.12 ANOVA Table for Transverse Fractures .......................................................41
4.13 Frequencies and Percentages of Butterfly Fractures ......................................42
4.14 ANOVA Table for Butterfly Fractures ..........................................................42
4.15 Descriptive Statistics for Variable: Radiating Fracture Lines .......................44
4.16 ANOVA Table for Radiating Fracture Lines .................................................45
4.17 Descriptive Statistics for Variable: Number of Pieces ..................................46
4.18 ANOVA Table for Number of Pieces ............................................................46
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LIST OF FIGURES
3.1 Display of distal vs. proximal end of deer femur .............................................14
3.2 Independent variables used in the present study ..............................................15
3.3 Removal of extra flesh from deer femora ........................................................16
3.4 Osteometric board and sliding caliper .............................................................17
3.5 Bones soaking on hot plates at less than 200 degrees Fahrenheit ....................18
3.6 Bones in warm water bath to loosen remaining tissue .....................................19
4.1 Right angles perpendicular to the bone shaft ...................................................23
4.2 Percentage of right angles by bone condition (within group) ..........................24
4.3 Acute angled bone ............................................................................................25
4.4 Percentage of acute angles by bone condition (within group) .........................26
4.5 Right angles .....................................................................................................27
4.6 Acute angles .....................................................................................................27
4.7 Example of jagged edged fracture ...................................................................28
4.8 Jagged edges by bone condition (within group) ..............................................29
4.9 Curved edge .....................................................................................................30
4.10 Percentage of curved edges by bone condition (within group) ......................31
4.11 Jagged edges ..................................................................................................32
4.12 Curved edges ..................................................................................................33
4.13 Rough edge morphology ................................................................................34
4.14 Rough edge morphology ................................................................................34
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4.15 Percentage of rough surfaces by bone condition (within group) ...................35
4.16 Smooth Fracture Surface ................................................................................36
4.17 Percentage of smooth surfaces by bone condition (within group) .................37
4.18 Smooth surfaces .............................................................................................38
4.19 Rough surfaces ...............................................................................................39
4.20 Percentage of transverse fractures by bone condition (within group) ...........40
4.21 Transverse fractures .......................................................................................41
4.22 Radiating fracture line ....................................................................................43
4.23 Curved Radiating fracture line .......................................................................44
4.24 Radiating fracture lines ..................................................................................44
4.25 Radiating fracture lines ..................................................................................45
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CHAPTER 1: INTRODUCTION
Interpersonal violence between and among individuals is a major problem in societies all
over the world today as well as in the past (Aufderheide et al., 1998). Bone breakage analysis is
one way to quantitatively examine a specific aspect of this widespread problem. In
bioarchaeology and in forensic work, there is a problem identifying perimortem from
postmortem breaks in long bones. Aside from the two extremes of green stick fractures in very
fresh bones and perfectly transverse breaks in dry bones, there is no set methodology to
categorize all of the breaks between the two extremes. Therefore, the question remains
unanswered as to whether or not there are specific criteria from which one can differentiate
between perimortem and postmortem breakage patterns in long bones.
Determining cause and manner of death is one of the top priorities in homicide
investigations. It is also important to the archaeologists who piece together human remains to
help reconstruct the individuals of past societies. In the much debated research on the practice of
cannibalism, bone fracture analysis has provided insight into perimortem fracture patterns. For
example, one site in Navatu, Fiji includes a “formal human burial site with a separate,
contemporaneous midden containing commingled fragmentary human and nonhuman bones”
(Degusta, 1999, p. 215) that are thought to have been butchered. An increase in knowledge about
bone fracture patterns may help to accurately determine the cause and manner of a person’s
death (Symes et al., 2005). The results of this study will be applicable to bioarchaeologists and
forensic scientists alike in determining the approximate time that the break took place. Sharp,
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irregular breaks are expected to be common in perimortem fractures because of the high moisture
content within the bone which absorbs and spreads out the stress of the trauma. A transverse
fracture is often seen on an “old” bone because of the lack of moisture in the bone (like a twig
breaking in half).
Actualistic research with human bones is limited by difficulties in obtaining large
samples for experiments that can be controlled and replicated. Fractured bones found in the field
could have been the result of trampling, animal gnawing, as well as natural events such as
landslides. Furthermore, the level of confidence and precision is increased in a controlled
laboratory setting (Villa and Mahieu, 1991). With this being the case, this study will use deer
femora which are easy to obtain in large quantities for a robust study sample.
The experimental study design included two experimental groups (old bones, n = 46; new
bones, n = 41). These groups were further divided, depending on which end of the bone was
analyzed (new distal, new proximal, old distal, old proximal). The purpose of this experiment
was to find out if certain fracture characteristics, such as smooth or rough fracture surfaces and
jagged or curved edges, appear more frequently in one group of bones than other groups.
Additionally, statistical tests were run to compare all groups. The study's 10 dependent variables
were measured and assigned values for the bone characteristics. Descriptive statistics,
correlational analyses, and analysis of variance tests were conducted. For all analyses, a two-
tailed, p = 0.05 alpha level was used to indicate statistical significance. A significant difference
between groups may help future researchers to categorize unknown bones as having either a
perimortem or a postmortem break.
The goals of this research are two-fold. The first is to determine if any variables appear in
one group of broken bones that do not occur in the other, supporting the idea that there is a
methodology to distinguish a perimortem break from a postmortem one. The second goal is to
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establish a more reliable methodology for observing these fracture pattern differences that is
applicable to both the fields of forensic science and archaeology. For example, current methods
for analyzing bones found at a crime scene or archaeological site include taking bones back to a
laboratory for a series of complex analyses. These procedures risk labeling and cataloging
mistakes, breakage, and other errors that would compromise the integrity of the evidence or
artifacts. I hypothesize that perimortem fracture patterns in deer femora will contain more acute
angles and smooth edges at the break site than right angles, which are thought to be more
prevalent in postmortem breaks. By facilitating the identification of perimortem breaks from
postmortem ones, this study has the capacity to make an important contribution to law
enforcement and archaeological sciences.
Current studies of skeletal trauma provide clues that can be used to discover information
about the lives of these deceased individuals, in addition to providing insight into the lives of the
people of ancient populations (Walker, 2001). Archaeologists have explored bone modifications
found in human burial middens to look for evidence of foul play. The discovery of bite marks,
cut marks, and fragmentation have led to theories of dismemberment and cannibalism as
common cultural practices among some ancient groups of people (Degusta, 2000; Villa &
Mahieu, 1991; White, 1992). Because the distribution of missing osteological elements has been
found in some cases to be identical in formal burials as well as in assemblages where there is
clear evidence of traumatic and perimortem dismemberment, it is imperative to look closely at
the fracture surfaces. Studies have recreated bone modifications on bones with varied
perimortem intervals in order to gather more information about the fracture surface
characteristics in relation to the time since death (Blasco et al., 2008).
Specifically, evidence of bone trauma can shed light on interpersonal violence in the field
of forensic science, as well as warfare and other lifestyle behaviors in the archaeological record
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(Aufderheide et al., 1998). Traumatic injuries found in ancient human skeletal remains are one of
the only direct sources of evidence for scientific testing of theories (Walker, 2001). Through the
scientific method, theories of warfare and violence can be objectively tested and are not as
vulnerable to the interpretative difficulties posed by literature, such as historical records and
ethnographic reports. However, all forms of evidence are subject to interpretive difficulties. The
other goal of this experiment is to find a method to differentiate bone fracture patterns in relation
to when they occurred in the life of the deceased individual. Specifically, criteria from which one
can distinguish perimortem and postmortem breakage patterns in long bones are of paramount
importance to the advancement of forensic science and bioarchaeology today (Wheatley, 2008).
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CHAPTER 2: LITERATURE REVIEW AND SIGNIFICANCE
The time around death or “perimortem interval” is important to forensic scientists
because it provides clues as to the cause and manner of a person’s death. It is known that bone
moisture content is strongly associated with fracture morphology (Wieberg and Wescott, 2008).
Bones begin losing moisture and their flexible collagen matrix at death; however, bones lose
moisture and flexibility slowly through decomposition, which complicates assessment of the
perimortem interval. A skeleton offers morphological clues that may aid scientists in determining
events that occurred in a person’s life. Functional implications for postural and locomotory
behavior and evidence for medical treatment were noted by Neri and Lancellotti (2004). An old
male skeleton found circa 1900 in good condition of preservation with known age, sex, and life-
activity is helpful in comparing an unknown skeleton (Neri and Lancellotti).
Wieberg and Wescott’s (2008) fracture study incorporated domestic pig (Sus scrofa)
bones in an effort to differentiate perimortem and postmortem fracture patterns. Fleshed ulnae,
femora, and tibia were fractured in groups of 10 every 28 days over a 141-day period. Their
results suggested an ambiguity in the perimortem interval definition that extended the full length
of the study.
Another issue to consider concerning perimortem and postmortem breakage patterns is
how to distinguish human induced fractures (such as cases involving foul play) from bones
modified by natural (biological and geological) agencies (Johnson, 1985). Villa and Mahieu
(1991) studied the breakage patterns of long bones to explore a cannibalism hypothesis. The site
where cannibalism was suspected had long bones with long and oblique fractures down the
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diaphysis. These bones were found without the rest of the skeleton. In the two sites where
cannibalism is not suspected, the bones were found in situ with the rest of the skeleton; these
breaks were either incomplete or the bone was broken in half.
Villa and Mahieu (1991) investigated three assemblages in Southern France in an attempt
to distinguish intentional breakage of human bones. Features examined were fracture angle,
outline, and edge, as well as shaft circumference, fragmentation, and length. The first assemblage
of bones was broken by pressure and impact of sediment layers on subfossil bone. Incomplete
fracture lines indicated the long-term process acting on progressively weakened and dried bones.
All bones were in contact with their conjoinable counterparts from articulated skeletons or
articulated anatomical segments.
The second group comprised what are thought to be cannibalized fresh long bones that
were broken for extraction of marrow. In all, 156 shafts were studied that were buried 15 cm
deep (3930 ± 130B.C.), indicating that this area was not a formal burial site. Bone breakage by
percussion on green bone was evidenced by multiple factors, most notably that the bone surfaces
are unweathered, uneroded, and had sharp fracture edges. Fragments of the same bone were not
found adjacent to each other (separated by up to 50 cm). Bones found next to each other were
either superimposed or positioned head to tail. It is thought that these bones were broken prior to
being thrown into the pit. In addition, 10 other clusters containing butchered animal bones had
similar sharp horizontal and vertical fracture edges; however, no tooth marks indicating animal
gnawing were present. Cutmarks were found on 30% of bones created by stone tools. These
marks are not recent, because the small trowel marks found at the third site do not mimic those
of stone tools. The location of cutmarks on the bones were similar to those of modern butchery
and comparable to those found in faunal assemblages; the bones were found in pristine
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condition. Cortical surfaces were found to be compact with dense texture and showed evidence
of one breakage cycle (intentional), displaying fresh, sharp edges (Villa and Mahieu, 1991).
The third site was a “collective burial with bones broken by the pick and shovel of the
land owner and amateur archaeologist” (Villa and Mahieu, 1991, p. 28). Bones were found in a
flat burial chamber. The color of the fracture surfaces indicated two cycles of breakage. The first
cycle indicated that either a roof collapsed on the burial chamber or sediment pressure impacted
the bones. The second cycle indicated haphazard and violent excavation methods were used;
these fracture surfaces were white. All species of bones were attributed to the genus Homo (Villa
and Mahieu). Results of this investigation led Villa and Mahieu to the conclusion that the latter
two sites contained bones broken by weathering and sediment layers, whereas the breaks found
at the first site were intentional and occurred during the perimortem interval suggesting the
possibility of cannibalism.
Essential to the study of bone fracture patterns is the understanding of bone as a material,
what physical properties are critical to its response as a material, and how its response is affected
by altering its physical properties. Bone microstructure governs bone failure and the resulting
fracture pattern. Fracture is a localized mechanical failure; therefore, microstructure properties
and mechanics must be acknowledged (Johnson, 1985).
Fresh green bone is bone that contains a high moisture content and fresh marrow in the
medullary cavity. Fresh marrow "greatly increases the ability to absorb stress" (Wheatley, 2008,
p. 1). In contrast to dry bone, fresh bone does not behave in a brittle or inflexible manner, but is
instead visoelastic (flowable and deformable) and ductile, capable of withstanding great amounts
of pressure and deformation before failure. Fresh long bones have a characteristic fracture
response to force known as spiral or curved fracture. A controversy exists in taphonomic and
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bone research over how spiral or curved fracture patterns are induced in fresh bone (Johnson,
1985).
Mammalian bone is a highly complex, multiphased, heterogeneous, composite material
that is visoelastic and anisotropic (having contrasting mechanical properties that respond
differently to an external stimulus but when combined are stronger than either substance alone).
Anisotropic analysis and failure theories for both bone and inorganic composites are based on
stress (local force intensities) and strain (local deformation) in the principal axial direction. Long
bones typically consist of two tissue forms, that of cancellous bone at the epiphyseal ends and
compact bone at the diaphysis. At the microstructural level, cancellous bone consists of an open
network of plates and columns known as trabeculae. Compact bone is a composite of laminated
and haversian bone. It consists of several features such as osteons, interstitial lamellae, lacunae,
and Volkmann's and haversian canals (Johnson, 1985).
Haversian bone contains osteons that surround the haversian canals, which contain blood
vessels. These secondary osteons are oriented longitudinally with the axis of the whole bone and
consist of concentric lamellae of collagen fibers oriented preferentially (longitudinally). This
preferential orientation governs bone reaction when the bone is stressed. Stress is defined as the
local force intensities or internal or intermolecular resistance within a body to the deformation
action of an outside force. Strain is the local deformation or change in the linear dimensions of a
body as the result of an outside application of force (Johnson, 1985).
Moisture content is an important aspect of bone strength. Air dried bone fractures more
easily due to water loss that decreases its ability to absorb stress and increases in stiffness that
makes the bone less flexible. Dry bone, therefore, behaves more as an inorganic material and
becomes brittle. Wet bone behaves in a ductile manner, being able to withstand a large amount of
strain before failure. The presence of moisture in living bone greatly enhances its energy-
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absorbing capacity. Also, because of the differences in structural properties of long bones, waves
of pressure are reflected and diffused in the epiphyses so that fresh bone fracture fronts do not
crosscut epiphyseal ends (Johnson, 1985).
Andrushko et al. (2005) noted trophy taking of enemies’ forearms during battle by
excavating a prehistoric archaeological site in central California. Holes were drilled through both
proximal and distal ends of the ulnae and radii. Interestingly for the current study, oblique
fractures were also found, indicating that the bone was broken around the time of death.
Researchers know this because the bone must have retained a high collagen content to allow for
this oddly shaped fracture. A dry bone would have been too brittle and would have either
shattered or broken off at a right angle. Another indicator of perimortem stress at the California
site is the cutmarks. Morphologically, they were similar in the human remains to the butchery
marks in other mammals commonly used as food. Other factors suggesting perimortem injury at
the site include the facts that no interior cortical bone shattering was observed and that the
interior color of the tool marks was the same as that of the remaining cortical surface (Andrushko
et al.) due to absorption of surrounding environmental pigmentation.
Niven (2007) discovered reindeer and horse bones, containing cut marks on upper long
bone shafts indicating meat removal (not disarticulation) possibly by early modern human groups
during the Pleistocene Aurignacian (31-32 ka.) This discovery was made at the Vogelherd Cave
site in Southwest Germany.
Researchers who excavated a site in Mangaia, in the Cook Islands, have argued that
environmental stressors caused the inhabitants to practice cannibalism between 1390 and 1470
A.D. (Steadman et al., 2000). The stratigraphic layer in question contains an earth oven filled
with human remains. The results of radiocarbon ([sup14]C) dating and accelerator-mass
spectrometer (AMS) analysis of the bones at this site correspond with sociopolitical stress and
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ethnographic records complied by missionaries and colonial officials. The stressors listed are
high-density populations, highly intensified production systems, reduced natural resources,
hierarchical political control and social stratification, and intense competition for land and other
resources. The human remains found in this strata were disarticulated and browned, but not
calcified (such as in the case of cremation). The ethnographic records indicate that “groups or
individuals practiced opportunistic cannibalism of nutritive necessity" (Steadman et al., p. 878).
The bones represent people of all ages and both sexes. Bones found in the stratigraphic layers
both above and below, contained primarily bones of other animals, such as pigs, dogs, and fish
(Steadman et al.).
At the Richards site in the Ohio Valley area, human remains were found commingled
with other faunal remains (such as deer) in midden pits (Edgar and Sciulli, 2006). All remains
had the same man-made butcher marks on the bone, leading the researchers to speculate that both
humans and deer were prepared for human consumption (Edgar and Sciulli). This same
butchering pattern has been found from the remains of the Chaco Anasazi culture in the
American Southwest (Hurlbut, 2000). Altered human bones of all ages and both sexes have been
found in over thirty sites around the area. Bone modification includes fragmentation,
disarticulation, cut marks, percussion fracture, burning, and endpolishing (from boiling). The
human remains in these sites resemble those of previous sites listed in that they were found with
other faunal remains known to be used for human consumption with the same butchery patterns
(Hurlbut).
On the other hand, similar perimortem injuries have been found in archaeological sites of
the prehistoric Puebloan cultures of the American Southwest, but Darling (1999) argues that this
evidence does not necessarily indicate cannibalism. There was evidence of perimortem butcher
marks and burned bones, but the ethnographic data reveals that there was a mass execution of
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witches (or people accused of witchcraft) during that period of time (Darling). Furthermore,
witches were associated with cannibalism, a practice that was repugnant to the Pueblo culture. It
is speculated that witches were dismembered to prevent any evil incarnations. It would not make
sense for this culture to practice the act of cannibalism, since it was considered taboo (Darling).
Criteria have been proposed to distinguish a human cremation site (as opposed to a
human “cooking” site). Because of the high heat required for cremation, the remaining bones
were calcified, warped, cracked and fractured. A true cremation site would contain no
perimortem fractures (unless the cultural standard dictated secondary burial in pots), such as
butcher marks or longitudinal and oblique breaks (Whyte, 2001).
Another use for modifying fresh bone is tool production. Awls and projectile points
produced from bone have been found at the Blombos Cave in Africa. The oldest tools are dated
to the Middle Stone Age (about 70,000 years ago), but most bone tools have been found in
Europe after 40,000 years ago (Henshilwood et al., 2001).
Significant differences have been found between some fracture pattern characteristics; for
example, wet (new or green) bones (postmortem interval < 4 days) have more smooth surfaces
and fracture lines radiating out from the site of trauma, whereas dry (old) bones (postmortem
interval > 2 months) have rougher edges around the site (Wheatley, 2008). These differences
were more likely to be found on the proximal surface of the fracture (bones were held in a vice
by the femoral head). The significant differences found between perimortem and postmortem
samples were on the proximal side of the break. In the current study, the bone was held in a vice
on the distal end. This variation on the previous research may allow researchers to determine
whether or not the differences found are true differences between the two bone groups (old vs.
new), or design-dependent differences.
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Bone weathering has revealed that femora resist outside elements better than other bones,
such as metatarsals (Janjua and Rogers, 2008). Temperature, humidity, sunlight, and
precipitation were all taken into account. The “microenvironment,” such as soil composition,
was taken into account as well. The rate of decomposition was noted over a set of specific time
periods (Janjua and Rodgers). Although this study is not specifically applicable to the current
study, it will be a valuable resource when accounting for environmental variables applicable to
the study.
Fracture shape is arguably the best indicator for exemplifying perimortem trauma (Symes
et al., 2005). Using microscopic analysis, a smooth, shearing fracture pattern can be seen in these
cases. This pattern is not usually seen in postmortem fractures. A continuous fracture line that
traverses the entire break is indicative of a postmortem injury. These fracture lines are also able
to be seen with the naked eye through the use of back-lighting (Symes et al.).
Even though the evidence supporting microscopic analysis is an important contribution to
the scientific community, one of the goals of this experiment is to discover these differences in
fracture patterns macroscopically. The reason for this design is so that a more convenient
methodology can be established and used in more practical situations. Using a methodology
where no equipment is necessary, forensic scientists and archaeologists alike can make
preliminary guesses as to the nature of the fracture while in the field at an archaeological site or
at a forensic crime scene.
Due to the results of previous research on the decomposition rates of different bone
samples (Johnson, 1985; Wheatley, 2008; Wieberg and Wescott, 2008), this experiment will use
a specific bone (deer femora) known to be robust and resistant to environmental variables that
could possibly affect the validity of the results. While femora is robust in both deer and humans,
there is a morphological difference. Deer femora, Odocoileus virginianus, "has both plexiform
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and haversian bone tissue, whereas, plexiform bone may only be present in human fetal or
pathological bone" (Wheatley, 2008, p. 1).
Despite the advances in research over the years in both the fields of forensic science and
archaeology concerning this specific problem, the results are largely inconclusive for a variety of
reasons. Currently, it is still extremely difficult to determine if any fracture characteristics appear
in a group of bones broken around the time of death that do not occur in an older group of bones
(and vice versa) because of large variations in the perimortem interval. More research is needed
to identify methods for distinguishing a perimortem break from a postmortem break. This
methodology will need to be replicable in many different and diverse settings and will need to
establish a more reliable methodology to use in observing fracture pattern differences.
The study hypothesis is that perimortem fracture patterns in deer femora will contain
more acute angles and smooth edges at the break site than right angles, which are thought to be
more prevalent in postmortem breaks. The acute and smooth edged breaks are common in
perimortem fractures because of the high moisture content within the bone, which absorbs and
spreads out the stress of the trauma. In addition, a transverse (or right-angled) fracture is often
seen on a postmortem bone because of the lack of moisture in the bone (like a twig breaking in
half). In the current study I analyzed these bone characteristics, and others, through statistical
tests in an attempt to establish a more convenient methodology for identifying bone fracture
characteristics, as previously discussed.
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CHAPTER 3: METHODS
The design of the present study is an experimental design with two experimental groups
(postmortem; n = 46; perimortem; n = 41). Details about the study population and the
experimental groups are provided in this chapter. The study design includes two independent
variables; the first is the condition of the bone (perimortem vs. postmortem), which refers to the
amount of time that elapsed between the death of the deer and the breaking of the femur.
Perimortem status means that the bones were broken less than two days after the death of the
deer. Postmortem status means the bones were broken at least sixty days after the death of the
deer. The second independent variable is the end of the bone that contains the fracture surface
(proximal vs. distal). The proximal end of the bone contains the femoral head and the distal end
is closer to the knee (Figure 3.1).
Figure 3.1. Display of distal vs. proximal end of deer femur.
Distal ProximalDistal Proximal
15
The significance of this variable relates to the position of the bone during breakage.
Bones were held in a vice on the distal end during breakage while the proximal end rested on a
foam pad. I wanted to determine if results (fracture patterns) could be attributed to bone end
stabilization (distal) vs. bone condition (old vs. new), alone. A diagram showing the study
independent variables is provided in Figure 3.2.
Figure 3.2. Independent variables used in the present study.
Description of Study Sample
Shortly before the end of deer-hunting season in January 2008, a research group
consisting of graduate and undergraduate students at the University of Alabama at Birmingham
gathered and processed bones used in the study. A sample of white-tailed deer (Odocoileus
virginianus) was obtained from two game-processing facilities near Birmingham, Alabama. One
group of deer femora (old) was left outdoors and uncovered on a nearby property to naturally dry
for a period of two months. The other group (new) was taken directly to a plot of land
approximately 20 foot X 30 foot, surrounded by a wooden fence, where the remaining tibiae and
soft tissue were removed from most of the femora; the remaining bones from the new group were
defleshed with scalpels and scissors the day of the experiment (Figure 3.3).
16
Figure 3.3. Removal of extra flesh from deer femora.
Research Design and Procedures
This study's experimental design consisted of two experimental groups (postmortem; n =
46; perimortem = new; n = 41). All femora were scored on a variety of characteristics (Degusta,
2000; Wheatley, 2008) that comprised the dependent variables. The following were used as
dependent variables: the presence or absence of (a) right angled fractures, (b) acute angled
fractures, (c) jagged edges along the fracture surface, (d) curved edges, (e) smooth bone surface
along the fracture line, (f) rough bone surface along the fracture surface, (g) transverse fractures,
(h) butterfly fractures, (i) the number of fracture lines, and (j) the number of pieces created
during the breaking of the bone. The independent variables were (a) the condition of the bone
(old, new) and (b) the end of the bone (proximal, distal; Wheatley, 2008). From the total number
of bones in the new group that were collected (n > 50), only 41 of the new bones broke on
impact; therefore, these 41 bones comprised the sample of new (perimortem) bones used in the
study. From the total number of bones in the old group that were collected (n > 50), only 46 of
17
the old bones broke on impact; therefore, these 46 bones comprised the sample of old
(postmortem) bones used in the study.
The bones used for analysis were taken to the bioengineering lab at The University of
Alabama-Birmingham (UAB) to conduct the experiment. New bones were tested within 2 days
of receipt and old bones were tested at least 60 days following receipt from the deer processing
facilities. In order to ensure and maintain a level of consistency, the same people, techniques,
and instruments were used to provide measurements of the bones. Two instruments were used
for bone measurements: an osteometric board and a sliding caliper. The osteometric board was
used to measure the length of long bones. The sliding caliper was used to measure smaller
increments, such as the anterior and posterior width, as well as lateral width of the deer femora.
All readings were recorded in millimeters. After the measurement was recorded, the bone was
assigned a case number and placed inside a plastic re-sealable bag (Figure 3.4).
Figure 3.4. Osteometric board and sliding caliper.
18
The deer femora were fractured using a Dynatup 8250 Drop Weight Impact Test Machine
(DWITM), which applied approximately 13.63 kg of concentrated and sudden compressive force
to the anterior surface of the mid-shaft of each bone. The striking surface of the drop weight
where it impacted the bone measured 3 in. x 4 in.2. The distal femur ends were secured in a vice.
The proximal ends were placed on a foam pad in an effort to generate a shearing force to cause a
natural fracture pattern.
After each impact, the femur fragments for each bone were gathered and returned to the
bone's numbered re-sealable bag. Each bag was then taken to the processing laboratory, where a
1:1 ratio of baking powder and enzymatic-action detergent was added to water and poured over
the bone fragments in their respective bags. Heat no greater than 200ºF was introduced in two-
hour increments. The heat loosened any remaining soft tissue on the bone and the marrow that
was left inside the bone (Figures 3.5 and 3.6).
Figure 3.5. Bones soaking on hot plates at less than 200ºF.
19
Figure 3.6. Bones in warm water bath to loosen remaining tissue.
The enzymatic-action detergent breaks up the residual oils in and around the bones. By
heating the bones at a temperature of less than 200ºF, the fracture surface retains the integrity of
its shape. Heating bones at higher temperatures than this may cause the structure of the bone to
break down. After each two-hour increment, the bones were removed from the heat and bits of
organic material removed. After three consecutive detergent baths, the bones were given a final
cleaning and placed in a diluted ammonia bath for another 2 hr. Any remaining oils or fats from
the specimens were extracted by the ammonia solution (Fenton, 2007). Bones were then rinsed
and placed under a fume hood to dry.
Tests and Measurements
All 10 of the dependent variables were measured and assigned values along the
fracture surface. Information about the dependent variables is provided in Appendix D. The
operational definitions for the dependent variables follow:
20
1. Right Angle: Does the bone have a right-angled fracture that encompasses at least 25%
of the fracture surface? (The remaining 75% of the fracture surface may reveal other features,
such as an acute angle on the same fracture surface as the right angle.)
2. Acute Angle: Does the bone have an acute-angled fracture that encompasses at least
25% of the fracture surface?
3. Jagged Edge: Does the bone have a jagged edge along the fracture surface that
encompasses at least 25% of the circumference?
4. Curved Edge: Does the bone have a curved edge that encompasses at least 25% of the
fracture surface? (Spiral fractures were classified as curved edges.)
5. Smooth Surface: Does the bone have a smooth surface that encompasses at least 25%
of the fracture surface?
6. Rough Surface: Does the bone have a rough edge that encompasses at least 25% of the
fracture surface?
7. Transverse Fracture: Does the bone have a transverse fracture along the Z-axis on at
least 75% of the circumference? A transverse fracture crosses the diaphysis at right angles to the
long axis of the bone (Byers, 2008).
8. Butterfly Fracture: Does the bone contain a butterfly fracture? (A butterfly fracture is a
bilateral winged-shaped fracture that occurs around the site of impact on the diaphysis; Byers,
2008).
9. Fracture Lines: How many fracture lines does the bone have?
10. Number of Pieces: Into how many pieces did the bone break?
Descriptive statistics, correlational analyses, and analysis of variance tests were
conducted. For all analyses, a two-tailed, p = .05 alpha level was used to indicate statistical
significance. All statistics were calculated using SPSS 15.0 (SPSS Inc., Chicago, IL).
21
Chapter 4: Results
Bones used in the study were examined on 10 dependent variables. Bones were
categorized as old/dry (postmortem) or as new/wet (perimortem) and were further classified
depending on the bone end (proximal, distal) measured. The angles along the fracture line of the
bones were then also measured to specifically look for right and acute angles. The presence or
absence of smooth and rough edges along the Y and Z -axes of the bone was recorded. I noted
the transverse fractures along the Z-axis, as well as jagged edges, curved edges, and butterfly
fractures. I also measured the number of pieces into which the bone broke and the number of
radiating fracture lines from the break site. I observed the bones without a microscope, so that
the methodology could be used and applied to samples in the field, as opposed to transporting the
samples back to a laboratory. To analyze the data, values were assigned to the variables and
entered the data into a statistical program. All statistics were calculated using SPSS 15.0 (SPSS
Inc., Chicago, IL). I then noted the results and their respective levels of significance.
Statistical tests used an alpha level of .05 for significance. A one-way multivariate
analysis of variance (MANOVA) was performed, examining the effects of the independent
variables (IVs) bone condition (old, new) and bone end observed (proximal, distal) on breakage
patterns (DVs) when breaking deer femora with a drop-weight impact machine. Using the
dependent variables as dichotomous data (0, 1) in analysis of variance calculations is supported
in the literature (Lunney, 2005) and was performed in order to compare all categories of
variables. Spearman's rho (similar to Pearson's r used for parametric data) is a nonparametric
22
procedure used to examine the correlation between two variables that are at least ordinal data.
Normal distribution is not needed. (Bone condition and number of occurrences of fracture
patterns were deemed at least ordinal data). The following patterns were analyzed: angles (right
and acute), edges (jagged and curved), surfaces (smooth and rough), transverse fractures,
butterfly fractures, number of fractures lines, and number of pieces created by the break (Table
4.1).
Table 4.1: Descriptive Statistics for Variables for Bone Characteristics
Variable f % of total Right angles Old 59 33.9 New 15 8.6 Acute angles Old 57 32.8 New 79 45.4 Jagged edges Old 64 36.8 New 55 31.6 Curved edges Old 76 43.7 New 70 40.2 Smooth surface Old 17 9.8 New 45 25.9 Rough surface Old 85 48.9 New 46 26.4 Transverse fracture Old 14 8.0 New 12 6.9 Butterfly fracture Old 9 10.3 New 6 6.9
Right angles were present in 33.9% of cases in the postmortem group and 8.6% in the
perimortem group. A Spearman rho correlation coefficient was calculated for the relationship
between the bone condition and right angles (Cronk, 2008). A negative correlation was found
(rho = -.463, p < .001) indicating a significant relationship between the two variables. In this
experiment, old bones tend to exhibit a right angle fracture surface. Note the morphological
23
characteristics in a postmortem bone (Figure 4.1), especially how the fracture surface along the
shaft forms a right angle across the top of the figure.
Figure 4.1. Right angles perpendicular to the bone shaft.
Table 4.2 contains information about the frequency of occurrence and absence of right
angles and their respective percentages. Figure 4.2 displays this data graphically. Table 4.4 and
Figure 4.5 contain results of statistical analyses for right angles.
Table 4.2: Frequency and Percentage of Right Angles
Variable f % within right
angles Right angles present Old proximal 31 41.9 New proximal 3 4.1 Old distal 28 37.8 New distal 12 16.2 Right angles absent Old proximal 30 15.0 New proximal 41 38.0 Old distal 27 18.0 New distal 38 29.0
24
Figure 4.2. Percentage of right angles by bone condition (within group).
Acute angles were present in 32.7% of cases in the postmortem group and 45.4% in the
perimortem group. A Spearman rho correlation coefficient was calculated for the relationship
between the bone condition and acute angles. A positive correlation was found (rho = .415, p <
.001) indicating a significant relationship between the two variables. In this experiment, new
bones tend to exhibit an acute angle fracture surface. Note the morphological characteristics in a
perimortem bone (Figure 4.3), especially how the fracture surface along the shaft dips inward
making a pointy edge with the outside surface, and forming an acute angle rather than a right
angle.
25
Figure 4.3. Acute angled bone.
Table 4.3 contains information about the frequency of occurrence and absence of acute
angles and their respective percentages. Figure 4.4 displays this data graphically. Figure 4.6 and
Table 4.4 contain results of statistical analyses for acute angles.
Table 4.3: Frequency and Percentage of Acute Angles
Variable f % within acute
angles Acute angles present Old proximal 30 22.1 New proximal 41 30.1 Old distal 27 19.9 New distal 38 27.9 Acute angles absent Old proximal 16 42.1 New proximal 0 0.0 Old distal 19 50.0 New distal 3 7.9
26
Figure 4.4. Percentage of acute angles by bone condition (within group). A one-way MANOVA was calculated examining the effect of breaking deer femora with
a drop-weight impact machine on fracture angles (right, acute). The analysis was significant (F =
9.270, df = 6, p < .001). As shown in Table 4.4, Pillai’s Trace value (p < .001) indicates the
significance in the multivariate model. A significant difference was found for right angles (F =
17.868, df = 3, p < .001) and for acute angles (F = 12.404, df = 3, p < .001) depending on bone
condition (old proximal, old distal, new proximal, new distal). Figures 4.5 and 4.6 are provided
to describe the relationships between the fracture angles (right, acute) and bone condition.
27
Figure 4.5. Right angles
Figure 4.6. Acute angles
28
Table 4.4: MANOVA Table for Right and Acute Angles
Effect Source F df Significance Partial Eta squared Right angles Pillai's Trace 17.868 3 < .001 .240 Acute angles Pillai's Trace 12.404 3 < .001 .180
Jagged fracture outlines were frequent and almost evenly distributed between old and
new groups (36.8%, 31.6%). A Spearman rho correlation coefficient was calculated for the
relationship between the bone condition and jagged edges. A correlation was not found (rho = -
.027, p = .726) indicating no significant relationship between the two variables. In this
experiment, old and new bones tend to exhibit a jagged fracture surface at similar rates. Figure
4.7 displays a jagged fracture surface.
Figure 4.7. Example of jagged edged fracture.
29
Table 4.5 contains information about the frequency of occurrence and absence of jagged
edges and their respective percentages. Figure 4.8 displays this data graphically. Figure 4.11 and
Table 4.7 contain results of statistical analyses for jagged edges.
Table 4.5: Frequency and Percentages of Jagged Edges
Variable f % within
jagged edges Jagged edges present Old proximal 28 23.5 New proximal 25 21.0 Old distal 36 30.3 New distal 30 25.2 Jagged edges absent Old proximal 18 32.7 New proximal 16 29.1 Old distal 10 18.2 New distal 11 20.0
Figure 4.8. Percentage of jagged edges by bone condition (within group).
30
Curved edges were present in 43.7% of cases in the postmortem group and 40.2% in the
perimortem group. A Spearman rho correlation coefficient was calculated for the relationship
between the bone condition and curved edges. A correlation was not found (rho = .037, p = .624)
indicating no significant relationship between the two variables. In this experiment, old and new
bones tended to exhibit a curved edge at similar rates. Note the morphological characteristics in
the bone in Figure 4.9, illustrating a curved edge.
Figure 4.9. Curved edge.
Table 4.6 contains information about the frequency of occurrence and absence of curved
edges and their respective percentages. Figure 4.10 displays this data graphically. Figure 4.12
and Table 4.7 contain results of statistical analyses for curved edges.
31
Table 4.6: Frequency and Percentage of Curved Edges
Variable f % within
curved edges Curved edges present Old proximal 43 29.5 New proximal 40 27.4 Old distal 33 22.6 New distal 30 20.5 Curved edges absent Old proximal 3 10.7 New proximal 1 3.6 Old distal 13 46.4 New distal 11 39.3
Figure 4.10. Percentage of curved edges by bone condition (within group).
A one-way MANOVA was calculated examining the effect of breaking deer femora with
a drop-weight impact machine on fracture edges (jagged, curved). The analysis was significant
(F = 3.404, df = 6, p = .003). As shown in Table 4.7, Pillai’s Trace value (p < .001) indicates the
32
significance in the multivariate model. A significant difference was not found for jagged edges
(F = 1.591, df = 3, p = .193) depending on bone condition (old proximal, old distal, new
proximal, new distal); however, for curved edges, a significant difference was found (F = 6.267,
df = 3, p < .001). Figures 4.11 and 4.12 are provided to describe the relationships between the
fracture edges (jagged, curved) and bone condition.
Figure 4.11. Jagged edges.
33
Figure 4.12. Curved edges.
Table 4.7: MANOVA Table for Jagged and Curved Edges
Effect Source F df Significance Partial Eta squared Jagged edges Pillai's Trace 1.591 3 .193 .027 Curved edges Pillai's Trace 6.267 3 < .001 .100
Rough edges were present in 64.9% of cases in the postmortem group and 35.1% in the
perimortem group. A Spearman rho correlation coefficient was calculated for the relationship
between the bone condition and rough edges. A negative correlation was found (rho = -.420, p <
.001) indicating a significant relationship between the two variables. In this experiment, old
bones tend to exhibit rough surfaces around the circumference. Note the morphological
characteristics in two postmortem bones (Figures 4.13 and 4.14), illustrating rough surfaces. If
you were to run your finger around the edges pictured in Figures 4.13 and 4.14, they would feel
rough.
34
Figure 4.13. Rough edge morphology.
Figure 4.14. Rough edge morphology.
Table 4.8 contains information about the frequency of occurrence and absence of rough
surfaces their respective percentages. Figure 4.15 displays this data graphically. Figure 4.18 and
Table 4.10 contain results of statistical analyses for rough surfaces.
35
Table 4.8: Frequency and Percentage of Rough Surfaces
Variable f % within
curved angles Rough surface present Old proximal 41 31.3 New proximal 13 9.9 Old distal 44 33.6 New distal 33 25.2 Rough surface absent Old proximal 5 11.6 New proximal 28 65.1 Old distal 2 4.7 New distal 8 18.6
Figure 4.15: Percentage of rough surfaces by bone condition (within group).
36
Smooth surfaces were present in 9.8% of cases in the postmortem group and 25.9% in the
perimortem group. A Spearman rho correlation coefficient was calculated for the relationship
between the bone condition and smooth surfaces. A positive correlation was found (rho = .379, p
< .001) indicating a significant relationship between the two variables. In this experiment, new
bones tend to exhibit a smooth fracture surface. Note the morphological characteristics in a
perimortem bone (Figure 4.16) illustrating a smooth fracture surface.
Figure 4.16
Table 4.9 contains information about the frequency of occurrence and absence of smooth
surfaces and their respective percentages. Figure 4.17 displays this data graphically. Figure 4.19
and Table 4.10 contain results of statistical analyses for smooth surfaces.
37
Table 4.9: Frequency and Percentage of Smooth Surfaces
Variable f % within
smooth surfaces Smooth surface present Old proximal 14 22.6 New proximal 34 54.8 Old distal 3 4.8 New distal 11 17.7 Smooth surface absent Old proximal 32 28.6 New proximal 7 6.2 Old distal 43 38.4 New distal 30 26.8
Figure 4.17. Percentage of smooth surfaces by bone condition (within group).
A one-way MANOVA was calculated examining the effect of breaking deer femora with
a drop-weight impact machine on fracture surfaces (smooth, rough). The analysis was significant
(F = 14.682, df = 6, p < .001). As shown in Table 4.10, Pillai’s Trace value (p < .001) indicates
38
the significance in the multivariate model. A significant difference was found for smooth
surfaces (F = 29.004, df = 3, p < .001) and for rough surfaces (F = 27.925, df = 3, p < .001)
depending on bone condition (old proximal, old distal, new proximal, new distal). Figures 4.18
and 4.19 are provided to describe the relationships between the fracture surfaces (smooth, rough)
and bone condition.
Figure 4.18. Smooth surfaces.
39
Figure 4.19. Rough surfaces.
Table 4.10: MANOVA Table for Smooth and Rough Surfaces
Effect Source F df Significance Partial Eta squared Smooth surfaces Pillai's Trace 29.004 3 < .001 .339 Rough surfaces Pillai's Trace 27.925 3 < .001 .330
Transverse fractures were present in 8.0% of cases in the postmortem group and 6.9% in
the perimortem group. A Spearman rho correlation coefficient was calculated for the relationship
between the bone condition and acute angles. A correlation was not found (rho = -.008, p = .915)
indicating no significant relationship between the two variables. In this experiment, new and old
bones tend to exhibit transverse fractures at a similar rate. An image of a transverse fracture was
not available for inclusion.
40
Table 4.11 contains information about the frequency of occurrence and absence of
transverse fractures and their respective percentages. Figure 4.20 displays this data graphically.
Figure 4.21 and Table 4.12 contain results of statistical analyses for transverse fractures.
Table 4.11: Frequency and Percentages of Transverse Fractures
Variable f
% within transverse fractures
Transverse fracture present Old proximal 2 7.7 New proximal 2 7.7 Old distal 12 46.2 New distal 10 38.5 Transverse fracture absent Old proximal 44 29.7 New proximal 39 26.4 Old distal 34 23.0 New distal 31 20.9
Figure 4.20. Percentage of transverse fractures by bone condition (within group).
41
A one-way ANOVA was calculated examining the effect of breaking deer femora with a
drop-weight impact machine on transverse fractures. A significant difference was found for
transverse fractures (F = 5.231, df = 3, p = .002) depending on bone condition (old proximal, old
distal, new proximal, new distal). Figure 4.21 is provided to describe the relationships between
the transverse fractures and bone condition.
Figure 4.21. Transverse fractures
Table 4.12: ANOVA Table for Transverse Fractures
Effect Source F df Significance Partial Eta squared Transverse fractures Linear 5.231 3 .002 .085
Butterfly fractures were present in 10.3% of cases in the postmortem group and 6.9% in
the perimortem group. A Spearman rho correlation coefficient was calculated for the relationship
42
between the bone condition and butterfly fractures. A correlation was not found (rho = -.065, p =
.549) indicating no significant relationship between the two variables. In this experiment, new
and old bones tend to exhibit butterfly fractures at a similar rate. An image of a butterfly fracture
was not available for inclusion.
Table 4.13 contains information about the frequency of occurrence and absence of
butterfly fractures and their respective percentages. Table 4.14 contains results of statistical
analyses for butterfly fractures.
Table 4.13: Frequencies and Percentages of Butterfly Fractures
Variable f
% within butterfly fractures
Butterfly fracture present Old 9 19.6 New 6 14.6 Butterfly fracture absent Old
New 37 35
80.4 85.4
A one-way ANOVA was calculated examining the effect of breaking deer femora with a
drop-weight impact machine on creating a butterfly fracture. A significant difference was not
found for creating a butterfly fracture (F = .362, df = 1, p = .549) depending on bone condition
(old, new). Table 4.14 displays the ANOVA statistics for butterfly fractures.
Table 4.14: ANOVA Table for Butterfly Fractures
Effect Source F df Significance Partial Eta squared Butterfly fractures Linear .362 1 .549 .004
43
Descriptive statistics for the number of radiating fracture lines present in each group is
provided in Table 4.15. A Spearman rho correlation coefficient was calculated for the
relationship between the bone condition (old, new) and number of radiating fracture lines. A
correlation was not found (rho = .089, p = .245) indicating no significant relationship between
the two variables. New and old bones tend to exhibit radiating fracture lines at a similar rate.
Figures 4.22 through 4.24 display examples of radiating fractures. Table 4.15 and Figure 4.25
contain statistical information about radiating fracture lines.
Figure 4.22. Radiating fracture line.
44
Figure 4.23. Radiating fracture line.
Figure 4.24. Radiating fracture line.
Table 4.15: Descriptive Statistics for Variable: Radiating Fracture Lines
Variable n M SD Radiating fracture lines Old proximal 46 .98 1.145 New proximal 41 1.34 1.389 Old distal 41 2.61 1.693 New distal 46 2.88 1.860
45
A one-way ANOVA was calculated examining the effect of breaking deer femora with a
drop-weight impact machine on number of radiating fracture lines. A significant difference was
found for radiating fracture lines (F = 15.991, df = 3, p < .001) depending on bone condition (old
proximal, old distal, new proximal, new distal). Figure 4.25 is provided to describe the
relationships between the radiating fracture lines and bone condition. Table 4.16 provides
ANOVA statistics for radiating fracture lines.
Figure 4.25. Radiating fracture lines.
Table 4.16 ANOVA Table for Radiating Fracture Lines
Effect Source F df Significance Partial Eta squared Radiating fractures Linear 15.991 3 < .001 .220
46
Descriptive statistics for the number of pieces resulting from the break are provided in
Table 4.17. The number of pieces ranged from 2 to 14 for the old group (n = 46, M = 5.85; SD =
2.82), and 2 to 20 for the new group (n = 41, M = 6.98, SD = 4.76). The means of the two groups
were similar; however, the standard deviation for the perimortem group was higher than that of
the postmortem group (4.76 and 2.82 respectively). A Spearman rho correlation coefficient was
calculated for the relationship between the bone condition (old, new) and number of pieces. A
correlation was not found (rho = .062, p = .570) indicating no significant relationship between
the two variables. New and old bones tend to exhibit similar numbers of pieces. Tables 4.17 and
4.18 contain statistical information about number of pieces.
Table 4.17: Descriptive Statistics for Variable: Number of Pieces
Variable n M SD Number of pieces Old 46 5.85 2.820 New 41 6.98 4.757
A one-way ANOVA was calculated examining the effect of breaking deer femora with a
drop-weight impact machine on number of pieces resulting from impact. A significant difference
was not found for number of pieces (F = 1.856, df = 1, p = .177) depending on bone condition
(old, new).
Table 4.18: ANOVA Table for Number of Pieces
Effect Source F df Significance Partial Eta squared Number of pieces Linear 1.856 1 .177 .021
47
48
Chapter 5: Discussion
This chapter discusses the interpretations of the study results and how they relate to my
original hypothesis and study goals. I hypothesized that perimortem fracture patterns in deer
femora would contain more acute angles and smooth surfaces at the break site than right angles
and rough surfaces and, conversely, that postmortem fractures would contain more right angles
and rough surfaces at the break site than acute angles and smooth surfaces. The goals of this
research were two-fold. The first was to determine if a methodology could be developed to
distinguish a postmortem bone fracture from a perimortem bone fracture. The second goal was to
establish a more reliable methodology for observing these fracture pattern differences that could
be applicable to both the fields of forensic science and archaeology.
For the variable of right angles, I found highly significant correlations between right
angles and the postmortem group. No differences were seen between proximal and distal ends
with regard to right angles. This indicates that the results (more right angles in the postmortem
group) were due to the actual condition of the bone, and not to the study design (i.e. which end of
the bone was held stationary). It is known from previous research (Johnson, 1985; Villa and
Mahieu, 1991; Wheatley, 2008; Wieberg and Wescott, 2008) that right angles are more prevalent
when very old and dry bones are fractured. The results of the current study support previous
findings, and demonstrate that this postmortem trait can be seen as early as 60 days after death.
Likewise, similar results were found in the variable of acute angles. A highly significant
correlation was found between acute angles and the perimortem group. Acute angles are more
likely to be found in new bones. No differences were seen between proximal and distal ends with
49
regard to acute angles. This result is also supported by the literature discussed in Chapter 2;
specifically, that acute angles are more prevalent when the fracture occurs around the time of
death (Villa and Mahieu, 1991; Wieberg and Wescott, 2008).
For the variable of jagged edges, no significant correlations were found between jagged
edges and the perimortem or the postmortem groups. No significant differences were found
between proximal and distal ends. Jagged edges have been found to be a postmortem trait in
previous research; however, results are dependent on the definition of jagged edges (Johnson,
1985; Villa and Mahieu, 1991). I classified a bone as having a jagged edge if it existed on 25%
of the fracture surface. This means that a bone from the perimortem group could have mostly
curves and smooth surfaces, but also have jagged edges around one 90 degree arc. If I changed
my criteria to 75%, I may have obtained results that agreed with the literature that supports
jagged edges as a postmortem trait (Johnson, 1985; Villa and Mahieu, 1991).
No significant correlations were identified between curved edges and the perimortem or
the postmortem groups. Interestingly, there was a significant difference found between proximal
and distal ends, regardless of bone age. Curved edges were almost always found on the proximal
side of the surface fracture. In the experiment, the proximal side was not secured when impacted
while the distal end was held stationary. This may have important implications when analyzing
the manner of how a bone was broken. With further study, this characteristic may give
researchers insight into the spatial orientation of the bone when broken, and possibly the
surrounding traumatic event.
Concerning the variable of smooth surfaces, a highly significant correlation was found
between smooth surfaces and the perimortem group. Further analysis with MANOVA indicated
that there was a highly significant difference between proximal perimortem and proximal
postmortem bones and between proximal perimortem and distal perimortem bones. Previous
50
research has shown that smooth surfaces are found to be a perimortem trait in general; however,
the findings of the present study lead me to speculate that there is some interaction taking place
among the variables.
A highly significant correlation was found between rough surfaces and the postmortem
group. Further analysis with MANOVA indicated a highly significant difference between
proximal perimortem and proximal postmortem bones and between proximal perimortem and
distal perimortem bones. Furthermore, MANOVA results indicated a significant difference
between proximal and distal bones regardless of bone condition (old, new). This leads me to
further speculate that interactions exist among variables, suggesting the necessity for further
research. While Wheatley (2008) found significant correlations between bone condition (old,
new) on both ends (proximal, distal), the different study designs preclude direct comparison of
statistical results.
No significant correlations were found between transverse fractures and bone condition
(old, new); however, further analysis with ANOVA indicated a significant difference between
proximal postmortem and distal postmortem bones. Since transverse fractures are widely
considered to be a postmortem trait (Wheatley, 2008; Wieberg and Wescott, 2008), especially in
very old bones, it makes sense that they would be found more often in the postmortem group.
However, since transverse fractures were found more often on the distal fracture surface of the
postmortem bones, this leads me to speculate that the difference is due to the design. The distal
end of the bones were held stable; therefore, less impact force could be absorbed and dissipated,
especially in postmortem bones, which have less moisture and elasticity. This finding supports
the theory that the perimortem interval is variable (Johnson, 1985; Wheatley, 2008; Wieberg and
Wescott, 2008).
51
No correlation was found between the number of radiating fracture lines and bone
condition (old, new). Results of ANOVA indicated a significant difference between proximal
and distal bone ends regardless of bone condition (old, new). The distal ends of bones in both
groups (old, new) had the same range (0-7) with respect to number of radiating fracture lines,
and the proximal ends of bones in both groups had similar ranges (0-5 and 0-4 respectively).
This leads me to speculate that radiating fracture lines are less a function of bone condition, and
more a function of study design. Since the distal end of each bone was held stable, the impact
force could not dissipate, causing the bone to fail more often on the distal end than on the
proximal end.
The number of pieces created from the break was not found to be significantly correlated
with bone condition (old, new). Interestingly, the standard deviation in the perimortem group
was 4.76 compared to 2.82 for the postmortem group. This means that perimortem bones are
highly variable with regard to number of pieces created by fracture trauma. New bones contain
more moisture, collagen matrix and bone marrow, which contribute to a more variable break. I
think this would be an intriguing avenue for further research.
Additional variables, such as fusion vs. nonfusion (Wheatley, 2008) might provide
additional information that would help to differentiate bone age. Wheatley used epiphyseal
fusion as a layer-effect variable in his fracture study. Epiphyseal fragments have not been
considered in the present study because epiphyses break differently from diaphyses, and this
study focused only on fracture patterns occurring on the diaphysis of the bone (Villa and Mahieu,
1991). Additionally, the availability of epiphyseal fragments is often restricted due to carnivore
activity. Carnivore-generated features are characterized by the presence of shafts or shaft
segments without their epiphyses (Villa and Mahieu). White (1992) found that femoral shafts are
over-represented relative to the epiphyseal ends at the Mancos study site.
52
Limitations of the present study included that data was gathered through visual
discrimination, which is subjective. The possibility of intra-observer error exists. Another
limitation of the study was that statistical analyses did not factor in size or chronological age of
the bone.
In summary, the study hypothesis was retained and the goals of the study were met.
Perimortem fracture patterns in deer femora did contain more acute angles and smooth surfaces
at the break site than right angles and rough surfaces; conversely, postmortem fractures
contained more right angles and rough surfaces at the break site than acute angles and smooth
surfaces. Based on study results, I believe a methodology could be developed to distinguish a
postmortem bone fracture from a perimortem bone fracture; however, other data would be
needed to triangulate with bone fracture patterns to make a definite determination.
53
CHAPTER 6: CONCLUSIONS
The present study explored some of the factors that may help scientists to accurately
classify a bone fracture as perimortem or postmortem. This research is important to
archaeologists who excavate sites containing osteological remains and to forensic scientists who
investigate crime scenes. Accurately deciphering when a break took place with respect to the
perimortem interval is important because this information can provide clues about interpersonal
violence, animal activity, or breakage that occurred simply due to sediment pressure. Living
bone has high moisture and collagen content; these characteristics begin to slowly decline over
time. Due to the higher moisture and collagen content of new bones, a perimortem break looks
different than a postmortem break.
The goals of this research were two-fold. The first was to determine if a methodology
could be developed to distinguish a postmortem bone fracture from a perimortem bone fracture.
The second goal was to establish a more reliable methodology for observing these fracture
pattern differences that could be applicable to both the fields of forensic science and
archaeology.
Due to the inaccessibility of a sufficient sample of human femora, deer bones were used
for this experiment. The experiment was carried out in a laboratory setting to control for as many
variables as possible. I compared two groups of bones: one group that was broken a few days
after death and another group that was broken approximately two months after death. I then
analyzed the bones for certain fracture patterns.
54
Previous research has explored fracture patterns in human bones, as well as other
mammal long bones in a variety of settings and states of decomposition (Degusta, 1999;
Johnson, 1985; Villa and Mahieu, 1991; Wheatley, 2008; Wieberg and Wescott, 2008). This
study included some variables used by previous researchers. As hypothesized, major findings of
the present study were that (a) perimortem fracture patterns in deer femora contained more acute
angles along the fracture surface, whereas postmortem bones were more likely to contain right
angles and (b) perimortem fractures were also more likely to have smooth surfaces at the break
site, as opposed to the postmortem group, which contained more rough surfaces.
A summary of results follow. Significant correlations were observed between bone
condition (old, new) and right angles (rho = -.463, p < .001, old bones tend to exhibit a right
angle); acute angles (rho = .415, p < .001, new bones tend to exhibit an acute angle); smooth
surface (rho = .379, p < .001, new bones tend to exhibit a smooth surface); and rough surface
(rho = -.420, p < .001, old bones tend to exhibit a rough surface).
Significant differences in curved edges were observed between proximal and distal ends,
regardless of bone condition (old, new). Curved edges were almost always found on the proximal
side of the surface fracture. Highly significant differences in smooth surfaces were observed
between proximal perimortem and proximal postmortem bones and between proximal
perimortem and distal perimortem bones. Highly significant differences in rough surfaces were
observed between proximal perimortem and proximal postmortem bones and between proximal
perimortem and distal perimortem bones. A significant difference in transverse fractures was
observed between proximal postmortem and distal postmortem bones. Finally, a significant
difference in radiating fractures was observed between proximal and distal bone ends regardless
of bone condition (old, new).
55
Results may be applicable to scientists in the fields of bioarchaeology and forensic
science; however, study results must be applied with caution to human cases. Although deer
bones are anatomically similar to human bones, the osteological differences between deer and
human bones may affect interpretation. It was found that certain variables were significantly
correlated with bone age (old, new) and bone end (proximal, distal), therefore supporting the
idea that there is a methodology to distinguish a postmortem bone fracture from a perimortem
bone fracture. Further research is necessary to determine which variables could be used to
accurately classify a fractured bone into perimortem or postmortem categories.
While the correlational statistic used in this study (Spearman's rho) is helpful to
understanding the relationship among variables, logistic regression analyses might allow for the
development of a model that could help to predict whether a bone is classified as perimortem or
postmortem based on the fracture pattern. Further research will be necessary to identify other
variables important to the development of a regression model. Findings of the present study are
applicable to both the fields of forensic science and archaeology. Statistical modeling may be
found to be useful in bridging the science of the present study with application in the field.
56
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Vunda. International Journal of Osteoarchaeology, 10(1), 76-92. Edgar, H. J. H., & Sciulli, P. W. (2006). Comparative human and deer (Odocoileus virginianus)
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Janjua, M. A., & Rogers, T. L. (2008). Bone weathering patterns of metatarsal v. femur and the
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Johnson, Eileen (1985). Current Developments in Bone Technology. Advances in archaeological method and theory, 8, 157-235.
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adaptations: A 20th century example of pre-modern healing. International Journal of Osteoarchaeology, 14(1), 60-66.
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Vogelherd, Germany. [Review]. Journal of Human Evolution, 53(4), 362-382. Steadman, D. W., Anton, S. C., & Kirch, P. V. (2000). Ana Manuku: A prehistoric ritualistic site
on Mangaia, Cook Islands (Cannibalism). Antiquity, 74(286), 873-883. Symes, S. A., Kroman, A. M., Rainwater, C. W., & Piper, A. L. (2005). Bone biomechanical
considerations in perimortem vs. postmortem thermal bone fractures: Fracture analyses on victims of suspicious fire scenes. American Journal of Physical Anthropology, 202-203.
Villa, P., & Mahieu, E. (1991). Breakage patterns of human long bones. Journal of Human
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fracture patterns in deer femora. Journal of Forensic Sciences, 53(1), 69-72. White, Tim D. (1992) Prehistoric Cannibalism at Mancos 5MTUMR-2346. Princeton University
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58
58
APPENDIX A:
DEER FEMORA DATA COLLECTION SHEET
1. Case #________ 2. Condition: ___Wet (Fresh) ___Dry (Old) 3. Time since death: _______<4 days ________ > 60 days 4. Prox. Fract. Angle on Z Axis: ___Right Angles 5. Dist. Fract. Angle on Z Axis: ___ Right Angles 6. Prox. Fract. Angle on Z Axis: ___ Acute Angles 7. Dist. Fract. Angle on Z Axis: ___ Acute Angles 8. Prox. Fract. Surface Morphology: ____Smooth 9. Dist. Fract. Surface Morphology: ____Smooth 10. Prox. Fract. Surface Morphology: ____Rough 11. Dist. Fract. Surface Morphology: ____Rough 12. Prox. Fract. Outline: ___Transverse 13. Dist. Fract. Outline: ___ Transverse 14. Prox. Fract. Outline: ___Curved 15. Dist. Fract. Outline: ___ Curved 16. Prox. Fract. Outline: ___ Jagged 17. Dist. Fract. Outline: ___ Jagged 18. Prox. Edges: ______Sharp Peaks 19. Dist. Edges: ______Sharp Peaks 20. Prox. Edges: ______Spiral Fractures 21. Dist. Edges: ______Spiral Fractures 22. Prox. Fract. Lines: (How Many?)______ 23. Dist. Fract. Lines: (How Many?)______ 24. Butterfly fracture: ______ 25. # of pieces: ______ >10mm. not including epiphyses.
Amendment table
Datum# Notes
59
59
APPENDIX B:
CODEBOOK FOR FRACTURE PATTERN VARIABLES
VARIABLE DESCRIPTION VARIABLE NAME VALUES FORMATCase identification number CASEID 1 TO 174 F3.1 End of bone BONEEND 1. Proximal F1.0
2. Distal
Condition (or age) of bone when broken BONECOND 1. Old Proximal F1.0 2. New Proximal
3. New Distal 4. Old Distal
Does the bone have a right angles that encompass RIGHTANG 0. Absent F1.0at least 25% of the fracture surface? 1. Present Does the bone have a acute angles that encompass ACUTEANG 0. Absent F1.0at least 25% of the fracture surface? 1. Present Does the bone have jagged edges that encompass JAGGEDED 0. Absent F1.0at least 25% of the fracture surface? 1. Present
Does the bone have a curved edges that encompass at least 25% of the fracture surface?
CURVED 0. Absent F1.01. Present
Does the bone have smooth edges that encompass SMOOTHFR 0. Absent F1.0at least 25% of the fracture surface? 1. Present
Is the bone surface along the Z-axis fracture line rough for at least 25% of the circumference?
ROUGHFRA 0. Absent F1.01. Present
Does the bone have a transverse fracture along the Z-axis encompassing at least 75% of the circumference?
TRANSVER 0. Absent F1.0
1. Present Does the bone contain any butterfly fractures? BUTTERFL 0. Absent F1.0 1. Present How many fracture lines does the bone have? RADIATIN Continuous F2.0 Into how many pieces did the bone break? NUMBEROF Continuous F2.0 Descriptive data. Note anomalies here. NOTES
60
60
APPENDIX C:
CORRELATIONAL TABLE
* Correlation is significant at the .05 level (2-tailed) **Correlation is significant at the .01 level (2-tailed)
Variable Correlation/Significance BONE
CONDITIONRIGHT
ANGLES ACUTE
ANGLES BONECONDITION Correlation Coefficient 1.000 -.002 -.073
Sig. (2-tailed) . .981 .342 RIGHTANGLES Correlation Coefficient -.002 1.000 -.614**
Sig. (2-tailed) .981 . .000 ACUTEANGLES Correlation Coefficient -.073 -.614** 1.000
Sig. (2-tailed) .342 .000 . JAGGEDEDGES Correlation Coefficient .156* -.190* .119
Sig. (2-tailed) .040 .012 .117 CURVEDEDGES Correlation Coefficient -.272** -.129 .147
Sig. (2-tailed) .000 .089 .053 SMOOTHFRACTURESURFACE Correlation Coefficient -.290** -.203** .219**
Sig. (2-tailed) .000 .007 .004 ROUGHFRACTURESURFACE Correlation Coefficient .165* .250** -.206**
Sig. (2-tailed) .030 .001 .006 TRANSVERSEFRACTURE Correlation Coefficient .267** .259** -.247**
Sig. (2-tailed) .000 .001 .001 BUTTERFLYFRACTURES Correlation Coefficient -.065 .196 -.255*
Sig. (2-tailed) .549 .069 .017 RADIATINGFRACTURELINES Correlation Coefficient .435** -.046 .006
Sig. (2-tailed) .000 .543 .932 NUMBEROFPIECES Correlation Coefficient .062 -.210 .260*
Sig. (2-tailed) .570 .051 .015 OLDVSNEW Correlation Coefficient .000 -.463** .415**
Sig. (2-tailed) 1.000 .000 .000
61
Correlational table, continued
* Correlation is significant at the .05 level (2-tailed) **Correlation is significant at the .01 level (2-tailed)
Variable Correlation/Significance JAGGED EDGES
CURVED EDGES
SMOOTH FRACTURESURFACE
BONECONDITION Correlation Coefficient .156* -.272** -.290**
Sig. (2-tailed) .040 .000 .000 RIGHTANGLES Correlation Coefficient -.190* -.129 -.203**
Sig. (2-tailed) .012 .089 .007 ACUTEANGLES Correlation Coefficient .119 .147 .219**
Sig. (2-tailed) .117 .053 .004 JAGGEDEDGES Correlation Coefficient 1.000 -.163* -.294**
Sig. (2-tailed) . .031 .000 CURVEDEDGES Correlation Coefficient -.163* 1.000 .326**
Sig. (2-tailed) .031 . .000 SMOOTHFRACTURESURFACE Correlation Coefficient -.294** .326** 1.000
Sig. (2-tailed) .000 .000 . ROUGHFRACTURESURFACE Correlation Coefficient .298** -.251** -.770**
Sig. (2-tailed) .000 .001 .000 TRANSVERSEFRACTURE Correlation Coefficient .112 -.825** -.278**
Sig. (2-tailed) .143 .000 .000 BUTTERFLYFRACTURES Correlation Coefficient -.009 -.045 -.078
Sig. (2-tailed) .937 .678 .472 RADIATINGFRACTURELINES Correlation Coefficient .296** -.222** -.313**
Sig. (2-tailed) .000 .003 .000 NUMBEROFPIECES Correlation Coefficient .121 .173 .128
Sig. (2-tailed) .263 .110 .238 OLDVSNEW Correlation Coefficient -.027 .037 .379**
Sig. (2-tailed) .726 .624 .000
62
Correlational table, continued
* Correlation is significant at the .05 level (2-tailed) **Correlation is significant at the .01 level (2-tailed)
Variable Correlation/Significance
ROUGH FRACTURESURFACE
TRANS-VERSE
FRACTURE
BUTTER-FLY
FRACTURESBONECONDITION Correlation Coefficient .165* .267** -.065
Sig. (2-tailed) .030 .000 .549 RIGHTANGLES Correlation Coefficient .250** .259** .196
Sig. (2-tailed) .001 .001 .069 ACUTEANGLES Correlation Coefficient -.206** -.247** -.255*
Sig. (2-tailed) .006 .001 .017 JAGGEDEDGES Correlation Coefficient .298** .112 -.009
Sig. (2-tailed) .000 .143 .937 CURVEDEDGES Correlation Coefficient -.251** -.825** -.045
Sig. (2-tailed) .001 .000 .678 SMOOTHFRACTURESURFACE Correlation Coefficient -.770** -.278** -.078
Sig. (2-tailed) .000 .000 .472 ROUGHFRACTURESURFACE Correlation Coefficient 1.000 .203** -.019
Sig. (2-tailed) . .007 .858 TRANSVERSEFRACTURE Correlation Coefficient .203** 1.000 .045
Sig. (2-tailed) .007 . .678 BUTTERFLYFRACTURES Correlation Coefficient -.019 .045 1.000
Sig. (2-tailed) .858 .678 . RADIATINGFRACTURELINES Correlation Coefficient .256** .225** -.019
Sig. (2-tailed) .001 .003 .860 NUMBEROFPIECES Correlation Coefficient -.067 -.173 -.230*
Sig. (2-tailed) .538 .110 .032 OLDVSNEW Correlation Coefficient -.420** -.008 -.065
Sig. (2-tailed) .000 .915 .549
63
Correlational table, continued
* Correlation is significant at the .05 level (2-tailed) **Correlation is significant at the .01 level (2-tailed)
Variable Correlation/Significance
RADIATINGFRACTURE
LINES NUMBER
OF PIECES OLD VS
NEW BONECONDITION Correlation Coefficient .435** .062 .000
Sig. (2-tailed) .000 .570 1.000 RIGHTANGLES Correlation Coefficient -.046 -.210 -.463**
Sig. (2-tailed) .543 .051 .000 ACUTEANGLES Correlation Coefficient .006 .260* .415**
Sig. (2-tailed) .932 .015 .000 JAGGEDEDGES Correlation Coefficient .296** .121 -.027
Sig. (2-tailed) .000 .263 .726 CURVEDEDGES Correlation Coefficient -.222** .173 .037
Sig. (2-tailed) .003 .110 .624 SMOOTHFRACTURESURFACE Correlation Coefficient -.313** .128 .379**
Sig. (2-tailed) .000 .238 .000 ROUGHFRACTURESURFACE Correlation Coefficient .256** -.067 -.420**
Sig. (2-tailed) .001 .538 .000 TRANSVERSEFRACTURE Correlation Coefficient .225** -.173 -.008
Sig. (2-tailed) .003 .110 .915 BUTTERFLYFRACTURES Correlation Coefficient -.019 -.230* -.065
Sig. (2-tailed) .860 .032 .549 RADIATINGFRACTURELINES Correlation Coefficient 1.000 .279** .089
Sig. (2-tailed) . .009 .245 NUMBEROFPIECES Correlation Coefficient .279** 1.000 .062
Sig. (2-tailed) .009 . .570 OLDVSNEW Correlation Coefficient .089 .062 1.000
Sig. (2-tailed) .245 .570 .
64
APPENDIX D: DESCRIPTION OF DEPENDENT VARIABLES
Variable Classification Statistic Right Angles: Right angled fractures are thought to be found more frequently in postmortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation MANOVA
Acute Angles: Acute angled fractures are thought to be found more frequently in perimortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation MANOVA
Jagged Edges: Jagged edges along the Z-axis are thought to be found more frequently in perimortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation MANOVA
Curved Edges: Curved edges are thought to be found more frequently in perimortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation MANOVA
Smooth Surfaces: Smooth bone surface along the Z-axis fracture line are thought to be found more frequently in perimortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation MANOVA
Rough Surfaces: Rough bone surface along the Z-axis fracture line are thought to be found more frequently in postmortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation MANOVA
Transverse Fractures: Transverse fractures are thought to be found more frequently in postmortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation ANOVA
Butterfly Fracture: Butterfly fractures are thought to be found more frequently in perimortem breaks
Ordinal: Absent (0) or Present (1) Dichotomous: 0/1
Spearman correlation
Fracture Lines: Number of fracture lineare thought to be found more frequentlyin postmortem breaks
Continuous Spearman correlation ANOVA
Number of Pieces: Number of pieces created during the breaking of the bone are thought to be found more frequently in perimortem breaks
Continuous Spearman correlation