There are two basic kinds of bone: cancellous and cortical. Cancellous bone is the softer, spongy bone tissue inside the long bones that are hollow. For example, the femur (thigh bone) and the humerus (upper arm) are long bones.

The inner cavity of these bones is filled with cancellous bone. It has low density and strength but there's a lot of it. Cancellous bone contains the red bone marrow where blood cells are produced. This is also where most of the blood vessels (arteries and veins) to supply the bone with oxygen and nutrients are located.

The outside layer of bone is called cortical bone. It is very hard and more like what we think of when we talk about bone. Osteoporosis has its biggest effect on cortical bone where fractures occur.

Active bone cells called osteoclasts and osteoblasts build up new bone and tear down old bone that needs to be replaced. With osteoporosis, there is an imbalance in this process. Tiny fractures can occur here that don't heal or aren't completely repaired.

If a patient is too osteoporotic for a screw or pin to hold, then medications such as the new bisphosphonates can be used. You may have heard of the most widely known bisphosphonate called Fosamax.

If your father is not already taking this medication, ask his doctor about it. A recent report suggests systemic use of bisphosphonates can help improve the fixation of hardware in osteoporotic bone.