The word wear refers to the loss of the surface structure of a material due to a constant and mechanical interaction with a surface or with an object, the permanent friction between the two structures allows us to appreciate the exponential loss of an element being the result of the action exerted between both bodies, however, this is achieved solely and exclusively with a mechanical action, that is, a constant movement between surfaces of two bodies, thanks to this it is possible to distinguish wear injuries from injuries caused by another degenerative factor, observing the same symptoms or results.

Wear is caused in several stages or phases, such as: primary stage (early), the speed of interaction between both bodies or structures is high or undergoes important changes, secondary stage (medium) the speed of wear or mechanical action between two systems is totally constant, that is to say, it is not subject to change and its disposition is permanent, finally there is the tertiary stage (advanced), where the exercise of interaction between both elements has a prolonged time in use, the speed is constant and reaches a point where the failure or rupture of the relationship is executed abruptly.

At the health level, we can also speak of wear and tear, and this is more directed to the interaction or constant mechanical exercise caused in the mobile joints (sites of union between bone and bone by means of ligaments); An example of this would be knee wear, where there is progressive wear between the joints of the femur with the tibia and fibula, the person presents symptoms such as: pain when in constant movement or standing, difficulty walking surfaces of different levels, pain when getting up from a chair or bed, crackling sounds in the knees when exerting a movement, etc.