Blunt Force Trauma - Lecture 17 Flashcards
1
Q
What is the most common form of trauma in an autopsy?
A
blunt force trauma
2
Q
What is blunt force trauma referring to?
A
the amount of kinetic energy (energy in motion) transferred to the bone from an object
3
Q
What is velocity referring to? How can velocity effect the amount of deformation to the bone?
A
- it is referring to the movement or displacement of the object overtime
- the higher the velocity the higher the deformation of the bone is
4
Q
What is deformation a factor of?
A
- loading (forces being applied)
- magnitude (amount of displacement)
5
Q
What are the two types of deformation? Explain them.
A
- Elastic deformation
- the collagen resisting the applied forces and once those forces are removed it returns back to its original shape
- temporary and a full recovery - Plastic deformation
- permanent damage
- example is if your bone is if a child how rickets their legs will begin to bow and stay that way
- area where deformation can occur
- not fractured
6
Q
What is the Yield Point?
A
- the transition between the bone being able to resist the applied forces to being permanently modified by those forces
- the point between elastic and plastic deformation
7
Q
What are object characteristics that affect bone deformation?
A
- size
- weight
- speed
- shape
8
Q
What are the types of applied forces (load)
A
- Unloaded
- Tension
- pulling forces that the bone is the least resistant to - Compression
- pushing forces that the bone is most resistant to - Bending
- combination of compression on one side and tension on the other
- side under tension will fracture - Shear
- when the bone goes in two different directions - Torsion
- twisting
9
Q
What are fracture types dependant on?
A
- characteristics of the object
- types of applied forces extended on the bone
10
Q
What are the three types of fractures?
A
- Complete Fractures
- two ends are completely separated - Incomplete Fractures
- portion fractured
- greenstick fracture - Displacement
- a compound fracture where one end of the bone sticks out of your skin
11
Q
What kind of fracture does tension (tensile forces) cause?
A
- a transverse fracture
- an incomplete transverse fracture called a greenstick fracture
- displacement
12
Q
What is an oblique fracture?
A
a fracture at an angle to the bone rather than 90 degrees
13
Q
What is a spiral fracture?
A
- caused by torsion
- moving anteriorly to posteriorly
- a combination of shearing and rotation
14
Q
What is a torus fracture?
A
- from compression
- small incomplete stress fractures
- will create a little bulge on either side of the bone
15
Q
What is a multidirectional fracture?
A
- initial fracture is transverse then the fracture lines follow the path of least resistance
16
Q
What is a comminuted fracture?
A
- bone breaks into many pieces
- can be a result of brittle bone disease
- likely results in displacement
- can be due to high velocity dynamic forces
- multidirectional fracture
17
Q
What is a butterfly fracture?
A
- comminuted and multidirectional fracture
- occurs under bending forces
- area of force is coming from the area with compression
- first point of failure at the area with tension directly opposite of the area of force
- direction of fracture moves around the compression creating oblique fractures around this area
18
Q
What are the types of trauma that occur to the long bones?
A
- transverse
- greenstick
- oblique
- spiral
- torus
- multidirectional
- comminuted
- butterfly fracture
19
Q
What is a concentric fracture?
A
- occurs in cranium
- concentric circles fracture out from point of force
- happens under high velocity
- also under repeated strikes to same location
20
Q
What is wastage?
A
- cortical bone removal (flaking or knapping) at margins of fracture lines
- suggests multiple blows to same area
21
Q
What is cortical delimitation?
A
- flaking of the cortical bone
22
Q
What is a radiating fracture?
A
- fracture lines radiating from the point of impact
- will follow path of least resistance
- size of the fractures indicate the amount of kinetic energy
- indicates the object was wider and the kinetic energy was dispersed
- if there is multiple blows radiating fractures will stop at preexisting fracture lines
23
Q
What is a buttress? Where are the 4 buttresses in the skull?
A
- thick areas of bone in the skull
1. midfrontal
2. midoccipital
3. posterior temporal
4. anterior temporal
24
Q
What is a depressed fracture?
A
- bone bending it at area of contact and bending out at borders of the fracture
- occurs in cranium due to the rounded nature of the cranium which focuses the force on a small point
- useful to calculate object’s size if its less than 16cm2
25
How can depressed fractures operate differently depending on intrinsic factors?
- young bone can result in an incomplete inward bend and no outward bend
- brittle or older bone results in a complete fracture
- weak trabecular bone results in an incomplete fracture
- weak inner table (inner side of the cranium) results in comminuted fracture
26
What is a spiderweb fracture?
- radiating fracture lines radiating from the same point as depressed and concentric fractures
- can create bone wedges
27
What is a hinge fracture?
a complete outward or inward fracture on one side of a depressed fracture
28
What is a LeFort fracture? What are the three different kinds and where are they?
- fractures that fracture around the buttresses of the face
1. LeFort 1
- travels between the alveolar and nasofrontal buttresses
2. LeFort 2
- travels between the nasofrontal and malar buttresses
3. LeFort 3
- travels below the anterior temporal and midfrontal buttresses
29
What is a ring fracture?
- caused by force pushing the spine through or into the skull
- at the base of the skull around the foramen magnum
30
What are the steps to BFT wound analysis
1. wound description
- placement on skeleton and type of fractures
2. estimate size, shape, and weight of instrument
3. estimate direction of blows
4. estimate number of blows
5. estimation of sequence of blows
6. miscellaneous estimations
