A condition in which bones gradually loose their mineral content and become weak and brittle?

This can happen for several different reasons: Parathyroid hormone (PTH) can be pulling calcium out of your bones to keep it "normal" in your blood... this will result in osteopenia (lack of bone) and eventually in osteoporosis, where your bones are somewhat like a honeycomb inside (lace like) instead of solid bone tissue. Many people with osteoporosis have bones that cannot support the body weight and will break.

There are other conditions that can result in loss of bone density, and/or making bones brittle.

Please have your physician diagnose your condition, and then once you have a diagnosis, you can research how to remedy it (or manage it). For example: Weight bearing exercises help build up bone, and several vitamin and mineral deficiencies can result in the loss of bone.