FRACTURED BONES

Problem. How does the body heal fracitured bones ? How well do broken bones heal themselves?

Background. Did you know that your bones are as alive as your skin or any other tissue in your body? Most people think that the bones in the skeleton are made of dead material. A close look would reveal some different information, however. Your bones grow rapidly during your first sixteen to eighteen years. Then they harden to form your adult skeleton. The marrow within some bones forms essential parts of your blood. Broken bones heal so completely that it is difficult to find the healed fracture. This evidence certainly points to the conclusion that bones are alive, in spite of their hardness.

Late in the seventeenth century an English physician, Dr. Clopton Havers, discovered that there are thousands of tiny canals lacing the bones. These canals, called Haversian canals after their discoverer, carry the blood vessels and nerves to the interior of the bones.

Around each canal is a group of cells called osteocytes. These cells form much of the living matter in the bones. One kind of osteocyte, an osteoblast, deposits the minerals that make up bones. This hard mineral content forms about 45 per cent of the weight of the skeleton. The other kind of osteocyte, the osteoclast, dissolves the hard calcium and other minerals in the bones. This dissolving

Explanation. When a bone breaks, whether it has split, broken into many pieces, or only cracked, there is apt to be damage to the blood vessels and nerves in the bone as well as to the bony substance itself. The repair of the break necessitates a repair of these vessels and nerves as well as a new deposit of calcium mixture at the site of the break.

As soon as the bone fragments are set so that they are close to each other, the osteocytes in the area begin to repair the break. The blood vessels grow back and help to carry away the debris dissolved by the osteoclasts. The osteoblasts deposit new calcium between the bones to cement them together. The osteoclasts dissolve away the rough edges and "polish up" the job. Finally, the break is so completely healed that it is not easily distinguished from the original bone.