When do human bones stop growing

Newborn babies have large amounts of cartilage in their bones, particularly at the ends of the bones in areas known as "growth plates. The cartilage continues to grow as the bones grow. The presence of a growth plate indicates that the bone is still growing. The ossification process is typically complete by the time a person reaches his or her mids , when their bones are as long as they will ever be.

Bone continues to change over the course of a person's lifetime. While they do not grow longer, for example, bones can become thicker during adulthood. Bone thickening is often in response to increased muscle activity, such as weight training. Bones can also heal and repair themselves. After bones stop getting longer, they continue to produce new bone tissue to replace old bone tissue.

In fact, the adult body replaces its skeleton every 7 to 10 years. Bones contain living tissue that renews itself regularly in a process known as bone turnover. The process happens in two stages. First, osteoblasts draw calcium from the bloodstream to build new bones. Next, cells known as osteoclasts dissolve the bone and return the calcium to the bloodstream. Bone turnover continues throughout life, but the process slows down with age.

During childhood through the teen years, the body adds new bone more quickly than it removes old bone, which helps to build bone mass. After the age of about 20, the body adds new bone more slowly. Eventually, the body removes old bone more than quickly than it adds bones, which causes us to lose bone mass.

When it comes to bone growth, fractures, and overall bone health, doctors use radiology in a number of ways. A radiologist can use x-rays to look for a broken bone, for example, and bone scans to detect diseases and tumors that affect bones. X-rays are also helpful in bone age studies, in which the radiologist looks at x-ray images of the growing plates of a child's left hand to estimate the maturity of a child's skeletal system. A radiologist can also perform densitometry to measure calcium and evaluate the density of a patient's bone.

This test is helpful in the diagnosis of osteoporosis and the prediction of bone fractures. Microscopic exams show these changes, which can indicate adult age to within 5 to 10 years. Younger adults have fewer and larger osteons. Older adults have smaller osteons and more osteon fragments, as new ones form and disrupt older ones. The bones that enclose the brain grow together during childhood along lines called cranial sutures.

During adulthood, bone "remodeling" may gradually erase these lines, at variable rates. Closure of cranial sutures gives general information about a person's age. It is best used with additional indicators to estimate age, or when other age indicators are unavailable.

Wear and tear on a body throughout a lifetime affects the skeleton. Arthritis of the spine and joints can reflect increasing age. Scientists also recognize many other clues to aging, such as the appearance of the rib ends and the cartilage that joins them to the sternum. 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. When cartilage growth ceases, usually in the early twenties, the epiphyseal plate completely ossifies so that only a thin epiphyseal line remains and the bones can no longer grow in length.

Bone growth is under the influence of growth hormone from the anterior pituitary gland and sex hormones from the ovaries and testes. Even though bones stop growing in length in early adulthood, they can continue to increase in thickness or diameter throughout life in response to stress from increased muscle activity or to weight.

The increase in diameter is called appositional growth. Osteoblasts in the periosteum form compact bone around the external bone surface. At the same time, osteoclasts in the endosteum break down bone on the internal bone surface, around the medullary cavity. These two processes together increase the diameter of the bone and, at the same time, keep the bone from becoming excessively heavy and bulky.