Which of the following statement(s) is/are true concerning the biomechanics of blunt trauma?

b. Shear strain injuries result from rapid acceleration or deceleration

c. Tensile strain results from direct compression of tissues

d. The tolerance of biologic tissue to trauma injury is directly proportional to the elasticity of the organ

The severity of any injury is directly proportionate to the amount of kinetic energy transferred to the tissues and the properties of that tissue which accept and dissipate the energy. Kinetic energy (KE) is a function of the mass (M) of an object and its velocity (V):

 KE = M x V^2 /2

It is clear from this relationship that changes in velocity alter the kinetic energy transferred more significantly than changes in mass. Therefore, a small child and a large adult, though significantly different in size and weight, are subjected to similar levels of energy transfer in a high-speed vehicular collision, the primary determinant being velocity rather than mass. The tolerance of a biologic tissue to traumatic injury is directly proportional to the elasticity of the organ—that is, its ability to return to its original shape and position. Elasticity is directly affected by the rate of loading, or the rate at which strain is applied to the tissues. Applying the force more rapidly increases the likelihood of exceeding tolerance. Blunt trauma results in two types of forces during impact. First, changes in speed (acceleration or deceleration) create shear strain, and second, deformity changes (stretch or compression) creates tensile strain.