Wound severity
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1 + distance of the target + intermediate target Wound severity • Tissue absortion of the KE is the most important and not KE potentialy possessed by the bulet • Characteristic of the missile • Velocity ++ • Mass • Ballistic shape • Design and composition • Yaw • Characteristic of the bones • Elasticity • Cohesiveness • Density • Shape
description
Wound severity. Tissue absortion of the KE is the most important and not KE potentialy possessed by the bulet Characteristic of the missile Velocity ++ Mass Ballistic shape Design and composition Yaw Characteristic of the bones Elasticity Cohesiveness Density Shape. - PowerPoint PPT Presentation
Transcript of Wound severity
1
+ distance of the target
+ intermediate target
Wound severity • Tissue absortion of the KE is the most
important and not KE potentialy possessed by the bulet
• Characteristic of the missile• Velocity ++• Mass• Ballistic shape • Design and composition• Yaw
• Characteristic of the bones• Elasticity• Cohesiveness• Density• Shape
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Extrinsic factors
• Importance : duration, direction and sequence of forces
• Rate of loading
• Stress : internal resistance resulting of the application of an external load
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Intrinsic factors
• Resistance of bone (haversian bone, medullary bone)
• Influence of ageing and pathology (osteoporosis, tumor…)
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FRACTUREPOINT
FRACTUREPOINT
PLASTIC DEFORMATION
PLASTIC DEFORMATION
ELASTIC DEFORMATIONELASTIC DEFORMATION
STRAIN
STRESS
STRESS / STRAIN CURVE FOR BONE
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• Low rate of loading
– Little energy absorbed : creation of linear fractures or no fracture
• High rate of loading
– Absorption of a high rate of energy : concentric fractrures or comminuted
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Distant gunshot wound
Abrasion Ring
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Bone (skull)
Basic mecanism of Ballistic injuries to bones
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Basic mecanism of Ballistic injuries to bones
Bone
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ENTRANCE
Bone
Outer table
Iner table
Round to oval sharp-edge
holeLarge bevelled-
out hole (internal bevelling)
« Cone shape »
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Entrance : exceptions
-Beveling on the outer table (?)
- Peterson, JFS, 1991. External bevelling AND internal bevelling
- Return of gaz through the bullet?
- Tempory cavity?
- Rotation of the bullet?
- Angle of the shot?
- Shape of the bullet?
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Entrance : exceptions
- Irregular:
- Yawing-Tumbling- Re-entrance
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Exemple of exit
Inside Outside
- Sometimes could have blunt trauma shape in case of suture or preexisting fracture
- Minimum beveling
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• Primary fracture
• Secondary fracture
• Tertiary fracture
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Morphology of ballistic fracture
• Primary fractures
– Plug formation– Bevelling
formation– « Petalling » in
thin bones
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Entrance/Exit
• The magitude of entrance associated fractures (radial, concentric) are often greater than exit associated fractures.
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Absence of radial or concentric fractures
KE was totaly absorbed by primary fracture
- long distance shot
- low velocity bullet
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Caliber determination by size of entrance wound ?
• Usualy bigger than the caliber because of the yaw
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Caliber determination
• It may never be possible to identify the specific caliber from a simple measurement of the defect
Berryman, Smith, Symes. JFS 1995
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KEYHOLE
defectBullet strinking
at a very shallow angle produces a
combined entrance/exit
type effect
Fragmentation of the bullet +++
Outside
Inside
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Ballistic injuries to long bones
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« Indirect fractures »?
• HV bullet passes near the bone but does not contact it directly
• Caused by the high pressure due to the expanding cavity
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Need to keep bones
– Evidence for Court
– Understand the mechanism of fractures and the path of the projectile
– Education
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CONCLUSION
• Importance of path/anthropo collaboration
• Importance to compare skin and bones
• Importance of X-ray (3D?)
• Importance to make a meticulous reconstruction
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CONCLUSION
• Mecanism of ballistic trauma are the same on all the bones
• Importance to differentiate HV trauma and LV trauma
• Not realy possible to predict a bullet diameter from the orifice (often smaller than their diameter)
