How do your bones grow

You can also help your child's bones get stronger by encouraging your child to do weight-bearing exercise. National Institute of Health Publications on bone health, osteoporosis and osteogenesis imperfecta.

College of Family Physicians of Canada Osteoporosis information for patients. International Osteoporosis Foundation Bone health brochures. When we think of bones, a lifeless skeleton usually comes to mind, but our bones are a living organ that grows and changes shape throughout our life.

Much of this shaping results from forces which press, pull and twist the skeleton as we move, and the biggest of these forces is caused by our muscles. Bones experience huge forces during movement. In fact, because muscles normally attach close to joints, muscular forces are even greater than these impact forces in the same way that you have to push harder to lift someone on a see-saw the closer you get to the middle.

As a result bones also experience huge impact and muscle force during daily tasks, totalling more than five times body weight even during walking. These forces squash, twist and bend bones. The shin bone briefly becomes nearly a millimetre shorter as your foot hits the ground when running. The bone senses these small changes, and can grow dramatically — in the months after starting exercise — in order to reduce the risk of breaking. Later, usually after birth, secondary ossification centers form in the epiphyses.

Ossification in the epiphyses is similar to that in the diaphysis except that the spongy bone is retained instead of being broken down to form a medullary cavity.

When secondary ossification is complete, the hyaline cartilage is totally replaced by bone except in two areas. A region of hyaline cartilage remains over the surface of the epiphysis as the articular cartilage and another area of cartilage remains between the epiphysis and diaphysis.

This is the epiphyseal plate or growth region. Bones grow in length at the epiphyseal plate by a process that is similar to endochondral ossification. The cartilage in the region of the epiphyseal plate next to the epiphysis continues to grow by mitosis. The chondrocytes, in the region next to the diaphysis, age and degenerate.

Osteoblasts move in and ossify the matrix to form bone. This process continues throughout childhood and the adolescent years until the cartilage growth slows and finally stops.

Your bone mass may stabilize or start slowly declining as bone loss overtakes bone buildup. Natural bone loss accelerates at mid-life. This is especially true for menopausal women , ages 55 to 65, as levels of protective estrogen decline. But by age 65, the rate of bone loss evens out for men and women. For the rest of your life, bone mass gradually wanes. If bone thinning makes your bone density drop below normal, you have osteopenia.