How would osteoporosis be defined?

Osteoporosis is primarily characterized by a decrease in bone mass and deterioration of bone tissue, which leads to increased fragility and vulnerability to fractures. The condition results in a significant reduction in bone density, affecting the structural integrity of bones. This decrease in bone substance occurs as a natural part of aging or can be influenced by various factors, including hormonal changes, nutritional deficiencies, and inactivity.

The other options, while related to bone health, do not correctly define osteoporosis. Avascular necrosis refers to the death of bone tissue due to a lack of blood supply, which is a different pathological condition. Pathological fractures can occur as a result of osteoporosis, but they do not define the disease itself. Hyperplasia of osteoblasts would indicate an increase in bone-forming cells, which contradicts the very definition of osteoporosis, where there is a loss of bone density due to reduced activity or number of these cells. Therefore, recognizing the core characteristic of osteoporosis as a decrease in bone substance is essential for understanding the disease's impact on women's health, particularly post-menopause when the risk increases significantly.