When does mechanical failure of tissue typically occur?

Mechanical failure of tissue typically occurs when the elastic limit of the tissue is exceeded. This point is crucial for understanding the biomechanics of tissue responses to stress and strain. Each type of tissue, whether it be muscle, ligament, or tendon, has a specific threshold for how much it can stretch and deform elastically without sustaining damage.

When the tissue is subject to forces beyond this elastic limit, it can undergo plastic deformation or even complete failure, such as tearing or rupturing. This makes option C the most accurate description of when mechanical failure occurs, as it directly addresses the relationship between applied stress and the tissue's structural integrity.

The other options misinterpret the conditions for mechanical failure. For example, fully healed tissue can still be subject to mechanical failure if forces are applied that exceed its capacity, and stretching tissue within its limits would typically not result in failure but rather predictably elastic deformation. Additionally, inflammation is a process that can weaken tissue but does not specifically define the moment of mechanical failure regarding elastic limits.