Trauma Animals chewing on bones weathering taphonomic processes etc Impart their energy so suddenly that bone reacts as brittle matter and shatters Judicial system ME s MD s jurors Forensic Anthropologists American Academy of Forensics Sciences Meet every year in various cities across the country Memberships constitutes the top forensic experts from all over the world Presentations Board certi cation exams Antemortem Before death Prosthetics serial numbers can lead to identi cation Postmortem After death Perimortem At or around the time or death Can help investigators evaluate violence against individuals i e force used on individual serious enough to leave evidence on bone Pathologist and Anthropologist Cooperation Correlate skin and soft tissue injury with patterns of skeletal trauma Two major kinds of injury to bone High velocity ballistic Blunt force sharp instrument also a form of blunt force Ex basketball Sharp force injuries combo Appearance of Bone Injury Re ects Shape Area Mass Speed Direction of instrument applying external force but also Intrinsic strength of the bone injured Anatomy of that bone Thickness of that bone Mineral content of that bone Overall health of the bone Function of Bone Support weight Anchor muscles against contracting forces Must be light yet strong for active movement if brittle would shatter If pliable like rope would collapse Visio elastic structure of bone provides adaptive responses to both extremes Lower energy bending forces slower impact deliver a gradual rate of loading Bone reacts more as a ductile material capable of showing plastic deformation Potentially a blend of characteristics incised bone combined with blunt force Trauma Extent of damage amount of energy from impacting object and size of impacted area These two responsible for unique morphology of fractures and defects caused by trauma Outside smooth round circular hole on external table Bullet punches through and creates a ragged cone shaped internal bevel on internal table If enough energy keeps going external table has beveled look Hydroxyapatite crystals and calcium salts are unyielding brittle component and collagen salts are the elastic yielding ductile component Trauma usually means extrinsic forces In general trauma a ects the skeleton in 4 ways Partial or complete break Abnormal displacement dislocation Disruption in nerve and or blood supply An arti cially induced abnormal shape or contour Skull has two tables outer and inner and a layer of spongy or trabecular bone in between diploe like a sandwich Gunshot Wounds Signature patterns Orientation of victim relative to shooter Sequence of wounds Entry and exit characteristics Bullet enters perpendicular to cranial bone 3 distinct fracture types for gunshot wounds Plug and spall Radiating fractures Heaving concentric Bone Beveling Does Not Lie Radiating fractures will continue expanding until pressure subside or energy is dissipated into an existing fracture or suture Fractures that radiate from an entrance wound travel faster than bullet Dixon Example a semicircular exit rather than a complete circle fracture traveled faster absorbed energy result semi circular exit wound Another type of bullet entrance wound a tangential or glancing or angled bullet entry position skips across skull In such a case projectile not only bevels bone inward but also chips it to product an outward bevel What about post cranial projectile wounds Can they be distinguished from blunt force in some cases yes Example Extrinsic Forces Initial impact projectile punches through external table to internal table minimal force may create this Radiating fractures cannot relieve pressure heaving con central fractures result to absorb pressure skull Greater force needed as pressure inside skull increases Fan shaped defect called a keyhole lesion Can result in an atypical exit wound Entry wound Trauma Line Single fracture At an angle Common in long bones Compressing the bone Fibula and tibia example Star Multiple fractures coming out from point of injury Shape weight material of striking object Rates and duration of loading at impact site Relative force of blow As noted earlier initial force bends bone Bone resists due to its structure if force is low rate and compressive and tensile strength are able to resis In this elastic stage bone can return to normal shape when pressure is removed If pressure increases bone enters plastic deformation and can no longer regain its original shape it is at a unique yield point Once extrinsic factors exceed the resisting strength bone fails fracture occurs Butter y fractures Types of fractures Linear Stellate Compression Oblique Compound Pond Hinge Comminuted Greekstick Sharp Force Trauma Blunt force blow delivered by sharp object Easier to determine angle in clothing and soft tissue Injury may never contact bone Blunt trauma to rib may represent force used to stab person without actually incising bone Elastic skin and organs must be considered when trying to assess direction of sharp trauma Maybe be able to suggest single edged blade double edged blade width thickness serrated straight spine features hilt shape Easier to look at the knife and predict the wound it will make than to look at a wound and suggest the type of instrument that made it Radiating circles on fracture Police ashlight Ripples in pond One side broken one just bent Ribs One side broken away similar to greenstick fracture Multiple bones and breaks in same bone Much more challenging in bone Breaking the bone in half Trauma Examples Ante mortem trauma can help ID Button osteoma Benign bony tumor