Kinematics of Trauma

Learning Objectives Define energy in the context of injury production. Describe relationship of injury and energy exchange. List phases of assessment and their characteristics Describe the mechanical principles of trauma Identify types of injuries and their kinematics

Kinematics of Trauma It can help explain the type of injury, outcomes and injury combinations. It indicates the need for additional diagnostic workup and reassessment. It is related to the type of injuring force and subsequent tissue response. The effect of injury depends on personal and environmental factors. Crash: is the energy exchange that occurs when an energy force (usually solid object) impacts the human body.

Phases of Assessment and Management Precrash phase: include the events that precede the incident E.g.: alcohol ingestion, past Hx, drugs,

Phases of Assessment and Management Crash phase: begins at time of impact between one moving object and a second object. Considerations include: The direction of energy exchange The amount of energy exchanged The effect of force on the patient

Phases of Assessment and Management Postcrash phase: begins as soon as energy from crash is absorbed. Information gathered about crash and precrash is used to manage patient.

General Principles To understand the effects of force on body it is important to understand two components (Energy and Anatomy) Laws of Energy and Motion: Newton’s first law of motion Conservation of energy Force = mass x acceleration (deceleration)

Factors Affecting Energy Exchange between Solid Object and Human Body Tissue Density Air filled organs Fluid filled organs Solid organs Contact area Cavitation

Mechanical Principles Blunt Trauma Penetrating Trauma

Blunt Trauma Forces involved are shear (changing speed) and compression (squeezing). Multiple injuries are common with blunt trauma They are more life threatening than penetrating injuries It includes MVCs, falls, assaults and contact sports, blast injuries

Types of MVCs Frontal impact Rear impact Lateral impact Rotational impact Rollover

Phases of pedestrian injuries The initial impact to the legs and sometimes the hips. The torso onto the hood of the vehicle. The victims falls off the vehicle and onto the ground, usually head first, with possible cervical spine trauma.

Falls kinematics assessment An estimation of height of the fall The surface on which the victim landed (compressibility) Part of body struck first

Sports injuries Mechanisms associated are too numerous General principles are the same as for MVCs

Blast injuries Primary injuries: caused by the pressure wave of the blast Secondary injuries (fragmentation) Tertiary injury: caused by hitting with object or object propelled by explosion.

Penetrating Trauma Injury produced by foreign object penetrating the tissue Penetrating objects are: Low Energy Weapons i.e. knife High Energy Weapons i.e. firearms Severity of injury is related to the structure damaged Mostly contaminated

Factors Affecting Severity of Penetrating Injury Profile: initial size of penetrating object. Tumble: angle or direction of entry Fragmentation