Osteoporosis is a condition in which the bones become fragile and brittle, leading to a higher risk of fractures (breaks or cracks) than in normal bone.
Osteoporosis occurs when bones lose minerals, such as calcium, more quickly than the body can replace them, leading to a loss of bone thickness (bone mass or density). As a result, bones become thinner and less dense, so that even a minor bump or accident can cause serious fractures. These are known as fragility or minimal trauma fractures.
Any bone can be affected by osteoporosis, but the most common sites are bones in the hip, spine, wrist, ribs, pelvis and upper arm. Osteoporosis usually has no signs or symptoms until a fracture happens - this is why osteoporosis is often called the 'silent disease'.