What condition involves a decrease in bone mass leading to increased fracture risk?

The condition characterized by a decrease in bone mass that significantly increases the risk of fractures is osteoporosis. This disease causes bones to become weak and brittle, making them more susceptible to breaking, even from minor falls or injuries. Osteoporosis develops when the creation of new bone doesn't keep up with the removal of old bone, leading to a reduction in overall bone density and strength.

In contrast, arthritis involves inflammation of the joints, chondromalacia refers to the softening and damage of the cartilage in joints, and osteoarthritis is a degenerative joint disease primarily affecting cartilage. While these conditions can lead to discomfort and mobility issues, they do not directly cause a decrease in bone mass or specifically increase fracture risk in the same manner as osteoporosis.