What does diastasis refer to?

Diastasis refers specifically to the separation of two bones that are normally connected by a ligament or other tissue. In the context of the provided choices, the correct answer captures this concept accurately, as it highlights the parallel displacement of these bones.

In practice, diastasis is often discussed in relation to certain injuries such as those affecting the pubic symphysis or in cases of separation of the tibia and fibula, where there is a displacement or disjointing that occurs, but still maintains some of the structural integrity of the area involved.

The other options do not accurately reflect the definition of diastasis: a total dislocation refers to a complete displacement of a joint, which is not the same as diastasis; a fracture of a solid joint pertains to a break rather than separation; and calcium depletion in bones relates to conditions such as osteoporosis, having no direct association with the concept of diastasis.