Bone development and regeneration happens throughout our lives and peak during adolescence.
Though the growth of bones occurs from infancy through early adulthood, not all bones in the body grow at the same rate.
Even the same bones grow at different rates in different individuals. Several factors play a role in determining the growth and development of each bone in the body. Let’s learn more about the development of bones and the factors influencing the rate of growth.
Skeletal development: Introduction
Skeletal development is the growth and development of the bones that form the skeletal system. Skeletal development begins during the initial days of pregnancy and continues until the bones are fully developed in late adolescence.
The growth and development of bones
Bone is living tissue and is the hardest among all connective tissues of the body. You might be surprised to know that bones consist of 50% water. The remaining solid part is made of minerals, especially calcium, and other cellular material. [1] [2]
Bones also contain cellular activity products and vascular tissues. The growth of the bones during childhood is highly dependent on the blood supply the bones receive through the vascular tissues as well as hormones that regulate the growth process.
This is why a healthy vascular stricture, as well as an adequate supply of calcium, are vital to the development of healthy bones.
According to the Hormone Health Network, “You may need extra calcium if you:
- Are a post-menopausal woman
- Eat few or no dairy products or leafy green vegetables
- Have a digestive disease that interferes with nutrient absorption” [3]
A lack of proper blood supply to any bone may affect the availability of essential nutrients and thus, reduce the rate of growth. This is one of the reasons why some bones may develop at a slower rate than others.
The bone cells that determine the development of the skeleton
Bone-forming cells called osteoblasts play a critical role in determining the rate of growth of bones. The thickness of the cortical layer and the structural arrangement of the bone tissues is also influenced by these cells.
Osteoclasts, on the other hand, are responsible for slowing down the growth of the bones as they break down the bone tissues. Osteoclasts are usually less active during childhood allowing the bones to grow fully.
The process of bone development occurs in 2 stages:
The process of bone development
Bone development can be divided into 2 processes.
The first process involves the intramembranous ossification. This is when primitive connective tissue, called the mesenchymal tissues (such as the maxilla, mandible, and skull), begin to form.
The second process involves the endochondral ossification during which actual bone tissues replace the existing hyaline cartilage.
Bone development continues all during early adulthood. The healthcare experts at the National Cancer Institute have mentioned, “Bone development continues throughout adulthood. Even after adult stature is attained, bone development continues for the repair of fractures and for remodeling to meet changing lifestyles.” [4]
Differences in the rate of bone development
The growth of different bones in the body may occur at different rates depending on the environmental and genetic factors. Hormones, mechanical factors, and diet can all play a role in reducing or increasing bone growth.
Remember, the growth rate may not always be the same in all parts of the same bone.
For example, the bones tend to grow faster at the proximal ends (nearest your trunk), such as the upper ends of femur or the forearm. The rate of bone growth is slower at the distal, or lower ends, of these bones.
The change in the rate of bone development can be attributed to the unique internal pattern of the bone tissues. Also, the direction in which the bones are formed along the epiphysis plane is influenced by the distribution and direction of the pressure line.
Bones tend to grow faster in the direction of the pressure line which is why the rate of development may differ among different bones in the body. [5] [6]
The growth of bones in terms of their diameter
The bones do not grow just in length, but also in diameter. The growth in diameter may continue even after the vertical growth has stopped. This is known as appositional growth. [7]
Appositional growth occurs as the osteoclasts resorb the old bone cells lining the medullary cavity, and as osteoblasts produce new bone cells just beneath the outer coating of the bone.
The erosion of the old bone cells and the deposition of new cells beneath the periosteum increases the diameter of the bones.
Depending on the activities of the osteoclasts and osteoblasts as well as the efficiency of the bone remodeling processes, the rate of development may vary among different bones of the body. [8] [9]
Factors responsible for different rates of bone development
- Gender: Though girls mature earlier than boys, their bones grow for a shorter duration so they have shorter bone lengths by approximately 7 percent. Adolescent girls are usually shorter-legged than boys of the same age. The proportional difference is more evident in their heights as well as the lengths of the hand and foot bones.
- Race: There are major population differences in the bone sizes, skeletal proportions, and ratios in people belonging to different races. For example; people of African ancestry usually have longer bones in the hands and feet while those of Japanese, Chinese, and Korean ancestry have relatively shorter bones. [10]
- Genetic: The difference in the relative growth rates of bones in different individuals is determined by their genetic makeup. The genetic factor can affect the development of bones in length as well as width.
- Diet: The rate of bone development is higher in people who eat a healthy diet rich in nutrients such as calcium and vitamin D. [11]
- Diseases affecting the bones: The rate of development of bones may be very slow in patients who suffer from disorders such as Gorham-Stout Disease. [12]
Conclusion
The bones grow at a higher rate during childhood. The formation of new bone is also much greater compared to bone loss or bone resorption during these years. Childhood is considered the best time to develop strong and healthy bones and to improve bone health.
https://whenithurtstomove.org/about-orthopaedics/how-bones-develop/
References:
- https://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookMUSSKEL.html
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4602167/
- https://www.hormone.org/your-health-and-hormones/bone-health/vitamin-d-and-calcium
- https://training.seer.cancer.gov/anatomy/skeletal/growth.html
- https://www.intechopen.com/books/osteogenesis-and-bone-regeneration/bone-development-and-growth
- https://www.ncbi.nlm.nih.gov/books/NBK539718/
- https://embryology.med.unsw.edu.au/embryology/index.php/Cartilage_Histology
- https://opentextbc.ca/anatomyandphysiology/chapter/6-4-bone-formation-and-development/
- https://training.seer.cancer.gov/anatomy/skeletal/growth.html
- http://www.healthofchildren.com/S/Skeletal-Development.html
- https://www.nof.org/patients/treatment/calciumvitamin-d/
- https://rarediseases.org/rare-diseases/gorham-stout-disease/
