Bone Density and Brittleness - Equally to Blame for Fractures as We Age
Bones are considered a connective tissue and are composed mostly of a specialized form of calcium phosphate. They are rigid, but have some slight elasticity due to also being partially composed of collagen. Some of their main functions within our bodies are to protect our organs, support our muscles, allow movement and to store minerals. What we don’t often think about, and one of their most important functions, is that red and white blood cells are also both produced within our bones. Without healthy bones, there can be any number of health problems.
Due to their construction, bones are more likely to be injured from a pulling motion than a pushing motion. Weight bearing exercise and healed or healing breaks will cause thickening in areas of bones. Apart from their usefulness and necessity, they store lots of important information. Forensic anthropologists can tell where a person lived, about their general health and any injuries they suffered by studying their bones. Though we are born with 270 bones, by the time we reach adulthood that number is reduced to 206 due to the fusing together of several bones including those within our skulls.
As We Age and the Natural Order of Things
Bones go through a constant process of cell turnover called remodeling. Within this process, cells called osteoclasts destroy old bone cells and other cells called osteoblasts create new bone cells, or osteocytes. In osteoporosis, the mineral density is reduced, causing a “thinning” of the bones’ mass. There are several therapeutic drugs on the market to try to combat this. They are typically bisphosphonates. Their function is to stop the cycle of turnover and kill the osteoclasts so that the bone is no longer destroyed, thus protecting and retaining as much mineral density as possible.
Along with reduced mineral density, it has recently been found that bones also deteriorate on a microscopic level, becoming far more brittle and therefore, more likely to fracture. This is considered a loss of quality of the bone tissue. Changes in the physical structure of the bones cause them to be weaker and less elastic. What was once able to stave off brittleness and weakness eventually fails to do so as our bones decline in quality. One comparison to this process would be to consider kiln dried wood. If all of the moisture is removed, when pressure is applied over time, it will splinter and break. The same principle can be considered with bones when their quality is compromised due to aging, only instead of splinters, bones develop cracks. As our bodies age, our bones are not able to repair these cracks and are left more vulnerable to fractures.
Each of these conditions alone would lead to increased risk of fracture. Coupled together and fractures are almost guaranteed. Each condition is independent of the other even though both are typically associated with aging. Calcium supplements with vitamin D to aid in absorption will assist with bone density, but there doesn’t appear to be a way to combat brittleness separately as of yet. Keeping muscles strong through low impact exercise will help to support bones and also protect them. It is well known that weight bearing exercise helps to keep our bones strong, but when faced with aging bones, the same rules may not apply.