Lecture 3: Pathology and Trauma of my Forensics course.
When FA's refer to age of deceased, they mean:
the age of the person at time of death (biological age), not how long they've been dead!
Age is more easily determined in children than adults. T or F?
Changes in bone occur slowly, constantly, and at specific points in a sequence. T or F?
True (e.g. Dental Eruption, Epiphyseal Fusion)
In the arm, growth is away from...
Humeral head and ulna are first to unite; distal radius and ulna are last. T or F?
In the leg, growth is towards...
Distal femur and fibula are first to unite; proximal tibia and fibula last to unite. T or F?
There are 2 phases of skull "growth":
1st phase: skeletal/ dental development (error range 1-3 years) until 18-25yo
2nd phase: a slow process of deterioration (less accurate)
Of the two sexes, which begins ossification/epiphyseal fusion earlier?
There is a known age range for postcranial fusion. However, it varies according to 3 factors:
1. the individual 2. sex 3. population
The age variance in epiphyseal fusion is observed in long bones especially (see slide 8)
a.Newborn has no epiphyses, just main bone without joint attachments b.3 year old child with epiphyses separate from main bone c.Adult who has completed growth; all epiphyses fused to form one single bone
For each long bone, how many areas of ossification are there, which fuse when growth's completed?
For long bones, the growth rate is...
different at each end.
At what age do deciduous teeth develop and roots form?
What is "occlusion" and at what age does it occur?
When teeth are completely erupted & when upper/lower jaws come together - teeth connect. Occurs ~3yo.
As the mandible growths, the teeth...
Around what age does the first permanent molar erupt?
1st permanent molar erupts ~6 yrs old.
Around what age does the second permanent molar erupt?
~ 12yrs old - not in occlusion until ~15 yrs.
After dentition is fully erupted, other methods are used to determine an individual's age. For an adult, age is determined by observing:
When aging adults, there's a very large error range of:
S.D of 12 yrs, even for bone histomorphometry.
Aging adults is largely based on:
1. Deterioration/degeneration of skeleton 2. Use as many methods as possible to improve reliability of estimates.
The plates of the cranial vault are --- at birth?
1. Have jagged lines where they attach over time 2. Fuse progressively with age 3. BUT there is variability in the timing of fusion 4. So, this reduces the value of suture closure patterns for age estimation - useful when other criteria not available
There are 4 Cranial Sutures Closure Grades (0-3). They comprise of:
Grade 0 - open sutures; no evidence of cranial suture closure.
Grade 1 - minimal (but some) closure; this score assigned to any 'minimal to moderate' closure.
Grade 2 - Significant closure; marked degree of closure but dome portion of the suture is still not completely fused.
open sutures, with no evidence of cranial suture closure.
Cranial Suture Closure Grade '1' entails:
minimal (but some) closure; is assigned to any 'minimal to moderate' closure.
Cranial Suture Closure Grade '2' entails:
significant closure; a marked degree of closure but dome portion of suture is still not completely fused.
Cranial Suture Closure Grade '3' entails:
complete obliteration; complete suture fusion.
Describe the pubic symphysis (3 points):
1. The pubic symphysis is a little bone that connects the two hip bones join in front, like a belt-buckle-effect. 2. Fibrocartilaginous joint that ossifies with age 3. Surface morphology changes with age
With age, changes occur to the pubic symphyses (bone connecting two hip bones at front). How does it change with age?
Furrows on face in youth, which smooth out, then become pitted (imagine seed-scraped-out melon) in old age.
The ventral margin becomes angled + dorsal plateau.
Determining a person's height, basically, involves measuring individual bones of people of known stature. This process is known as the:
•Stature correlates with limb bone length across all ages •Change over time - stature in 1900's vs present day •Imperfect - sex, age & ancestry
Stature correlates with limb bone length across all ages. T or F?
What 3 things influence people's stature?
Sex, age, and ancestry
When measuring for height, it's important to...
...landmarks for long bone measurements.•
E.g. femur - maximum length or physiological length
Strong correlation between lengths of individual long bones - e.g. humerus, radius, ulna
Do males overestimate in stature?
Are left and right sides of the skeleton completely symmetrical generally, or asymmetrical?
Generally, minor asymmetry between left and right sides only. •Strong correlation between lengths of individual bones
Two ways to determine height include: 1. full skeleton technique 2. individual long bone length measurements What are the values of each?
1. the full skeleton approach is more accurate 2. measuring long bone lengths is easier to do, and thus, is most often used.
Important: Do the lower limb bones provide stronger stature estimates?
Yes! Yes! Yessss!
Because people lose stature with age, what must be adjusted?
Stature estimates for individual 45+ need to be adjusted to reflect their loss of stature.
•Dry bone length should be corrected upward - fresh bone is 1.5% larger •There is always an error range associated with estimating stature - you must always report this
Dry bone length should be corrected upward (when determining stature) because...
... fresh bone is 1.5% larger.
You must always report error ranges when determining stature of individuals, because...
...stature determinations are always estimates only.
Evidence of trauma & pathology is useful for (2p):
• identifying cause & manner of death •Potentially useful for victim identification
Pathology refers to...
Many illnesses leave physical traces on your bones. Around how many types of illnesses can leave these traces?
There are around 14 types of illnesses that can leave traces on bones.
What are the 14 types of illnesses (pathologies) which leave traces on bones?
•Leukaemia -Marrow cavity & vascular system get clogged with leukaemic cells -Body increases the number of red blood cell making sites (ie more red marrow sites)
Pathology #6, Neoplastic (Cancer), includes:
• Benign, or • Malignant (2 types): -Primary -Secondary metastases
Pathology #7, Hormonal, involves:
• High cortisol which breaks down bone collagen -Adrenal Adenoma, Pituitary tumor, Lung tumor excreting hormones • Excess Growth Hormone -Gigantism in children -Acromegaly in adults • Osteoporosis after menopause
Pathology #8, Metabolic, involves:
•Scurvy - Vitamin C deficiency •Rickets - Vitamin D deficiency •Renal Rickets - Kidney failure causes lack of activated Vitamin D •Iron Deficiency Anaemia •Gout - Uric acid crystals deposited in joints •Fluorosis - Excess of fluoride (eg Palmyra) •Stones - Kidney, bladder, calcified cysts, faecoliths, lithopedion.
Pathology #9, Drugs, include:
•Tetracycline •Corticosteroids •Thalidomide
Pathology #10, Psychogenic, includes:
•Bone and tooth modification •Plastic surgery and implants
Pathology #11, Idiopathic, involves:
•Peculiar to you •No specific cause •Diffuse Idiopathic Skeletal Hyperostosis - (D.I.S.H.)
Pathology #12, Iatrogenic, involves:
• "Caused by healers" • Amputation of wrong limb • Cosmetic surgery gone wrong • Severe medical treatments causing death of patient
• Being able to identify the type of fracture & its location, which will help you to: - Determine how trauma was incurred - Accidental or intentional - Direction of force - Sequence of blows or shots • Careful examination & reconstruction of fractured bone
Interpretation of fracture patterns (trauma) includes:
1. Reconstructing events surrounding injury & death 2. Sequencing of the blows or events 3. Direction of bullets or force 4. Object characteristics
How can the interpretation of trauma help with identification?
1. It depends on your ability to find signs of previous disease, trauma or infection - link to individual 2. It can also be used to help with assessing the sequence of events at mass graves & massacres
It's extremely important to preserve any unique characteristics present in the remains during recovery. Examples:
1. Knife & cut marks 2. Beveling around gun shot entry & exit wounds 3. Fracture edges / bone remodeling
•Creation of new fractures problematic •Vital to recover every fragment of bone for accurate reconstruction of bone, fracture patterns & sequences
In your bone micro-structure, strength is derived from ----------- crystals, and flexibility/elasticity from ------- fibres (protein).
1. Strength derived from hydroxyapatite crystals embedded in collagen
2. Flexibility/elasticity from collagen fibres (protein)
When bones are strong and flexible (hydroxyapatite crystals in collagen & collagen fibres, respectively), they become:
fracture resistant, which increases durability and function.
What are the 2 different types of bone?
1. Compact 2. Spongy or cancellous
A bone's structure has 3 parts, made up of 2 types of bone:
Fracture patterns reflect, A. Bone Morphology (3):
•Bone morphology: - Configuration of compact & cancellous bone - Differential bone density - Suture location
Fracture patterns also reflect, B. The shape & structure of bone & areas of buttressing:
The shape & structure of bone + areas of buttressing: - Controls the path through which the fracture propagates - Fracture takes path of least resistance
The likelihood of a bone fracturing, and the extent/patterning of a fracture is determined by 2 main factors:
1. Extrinsic factors: direction of force, magnitude & duration of force, rate of force 2. Intrinsic factors: bone's capacity to absorb energy, bone stiffness, density, & fatigue strength.
Bone is a viscoelastic material, which means:
...it is twice as strong under compression as under tension. *Compression - the action of being pressed in *Tension - the state of being stretched tight
When bone is angulated, it will fracture how first?
When bone is angulated it will fracture under tension first. Fracture initiates under tension - as it progresses to concave side it changes direction (shear forces).
For a bone to be angulated, it has:
Top side under tension, and bottom side under compression.
Bone has a significant elastic component, which means that...
1. it initially deforms with applied load 2. when the load is removed it can resume its original shape
The more slowly a load is applied to bone....
...the greater the load that bone can withstand.
If a load causes bone to exceed its elastic limit
...it enters the plastic phase of deformation. •Once bone enters this phase it will always be deformed.
Once plastic deformation of bone occurs, we cannot...
...accurately reconstruct the bone to determine the fracture pattern or pre-fracture characteristics.
If a load is applied to bone rapidly, e.g. a high-velocity bullet, bone behaves like a...
...like a brittle material • Imparts so much energy into the skull & soft tissues that there is failure of the bone & extensive fracturing. • A different gun & slower-velocity bullet will result in much less damage.
While a high-velocity bullet will cause immediate bone failure, due to the rapid load applied, a slower-velocity bullet will result in...
...much less damage.
"Blunt Force Trauma" refers to ? And is caused by ?
Blunt force trauma refers to trauma caused by a blunt object: - E.G. baseball bat, the floor, a dashboard, bumper bar Is caused by: - E.G. car accidents, pedestrian accidents, falls, assaults, workplace accidents.
Bone biomechanics determine how it fractures. As such, fracture won't always occur at the point of impact. For example:
If blunt force applied to top of cranium, then fractures appear further down parietal - peripheral. (imagine cracks forming on side of a pie you're squishing from the top).
A blunt object, as a weapon to skull, will cause...
...in-bending/ compression at the point of impact - out-bending/ tension in peripheral areas
Once a load is lifted, bone
•Once load is lifted - bone rebounds in the elastic stage •In region of tension - encourages peripheral fractures - towards & away point of impact
A fracture will take the path of ----- resistance...
A fracture will take the path of LEAST resistance, and will propogate until it's energy is dissipated.
In the skull, some regions are more prone to fracture than others. T or F?
Which type of curvature - gradual or sharp, is LESS resistant to violence?
Gradual curvature = less resistant to violence
Why are sutures involves in many skull fractures?
Sutures involved in many fractures because they are weak regions in the skull (fibrous).
Fractures will tend toward areas of ---- curvature?