The metaphysis is the area of the long bones that is located between the epiphysis (upper and lower part) and the diaphysis (central part). In the bones of children and adolescents who are growing, the metaphysis is separated from the epiphysis by a transitional area called the growth plate, which allows the bones to lengthen.
Once bone development ends, around age 18 for women and age 21 for men, the growth plate calcifies and the metaphysis is permanently attached to the epiphysis. This union is known as the epiphyseal line.
By OpenStax College - Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, commons.wikimedia.org
Histologically this part of the bone is made up of trabecular or spongy bone tissue, that is, it contains bone marrow, which is responsible for the development of blood cells and their release into the stream.
The area of the metaphysis is richly vascularized and these blood vessels are responsible for supplying the growth cartilage that is near it.
When metaphysis fracture occurs, the growth plate may be involved. This type of injury occurs in sports children or in the case of severe trauma.
Treatment is simple, but the diagnosis can go unnoticed, so the patient should be seen by a specialist if they have a long bone injury.
Histology
Long bones consist of three parts, the epiphyses that are located at the ends, the diaphysis, which forms the middle part of the bone, and the metaphysis that is located between these two portions.
The metaphysis is an area found in the long bones. During growth it is separated from the epiphysis by a specialized cellular cartilage, which is called growth cartilage.
X-ray of the lower end of the tibia and fibula. The red arrow indicates the location of the growth plate of the tibia. From Modified from Gilo1969 - WIKIMEDIA COMMONSFile: Tib fib growth plates.jpg, CC BY-SA 4.0, commons.wikimedia.org
In large bones such as the femur, tibia or radius, there are two metaphyses. One at the top, or proximal, and one bottom or distal. Smaller long bones, such as the interphalangeal or metacarpal bones, have a single metaphysis.
The bone tissue that forms the metaphysis is trabecular or spongy. This type of tissue withstands rebound impact well and transfers the vibrations from these impacts to hard or compact bone tissue. It also has an architecture that consists of small bony partitions within which is the bone marrow.
Bone tissue according to the parts of the bone. From OpenStax College - WIKIMEDIA COMMONSFile: 603 Anatomy of Long Bone.jpg, CC BY-SA 4.0, commons.wikimedia.org
Blood cells are formed within the bone marrow that will be released into the circulation.
The metaphysis is a fundamental part of the bone that contains a complicated network of blood vessels that are responsible for nourishing the nearby cartilage.
Embryology
The cells that form bones begin to differentiate from 4 to week of gestation, however, is not until 8 a week you can recognize an organized formation of what will be the skeleton.
Long bones originate from 9 to 10 a week and the process begins with the formation of cartilaginous tissue around which cells are grouped to differentiate into osteocytes, or bone cells.
The diaphyses are the first structures to calcify while the epiphyses and metaphyses have a more complex formation process.
The diaphysis is made up of bone tissue, but at its junction with the metaphysis, a cartilaginous tissue is formed that prevents calcification and adhesion between these parts.
The cartilage found in this area is a specialized tissue and has the property of lengthening with growth.
In long bones, the differentiation between the metaphysis and the diaphysis can be clearly observed through a conventional radiological study.
X-ray of the hand. Note the growth plate separating the metaphysis from the epiphysis on the radio By Internet Archive Book Images - flickr.com
When the child is born, its skeleton is fully formed and the long bones have these sections of cartilage that will allow growth.
Features
During the growth period, the bones are not completely calcified. This means that there are areas that are maintained with a softer and more elastic tissue than bone, which allows it to lengthen.
Between the epiphyses and metaphyses is this tissue called growth plate or growth plate.
The growth plate does not contain blood vessels. In young children it is nourished by the vasculature of the epiphysis, but in adolescents and adults the vascular network of the metaphyses is responsible for supplying this area.
The irrigation is given in a 1) intraosseous way, through the channels that are formed inside the spongy tissue, 2) and extraosseous, by the blood vessels that are on the surface of the metaphysis.
This type of irrigation prevents the growth plate from losing its blood supply in the event of a trauma that damages the epiphysis.
Another important function of the metaphysis is to absorb the impacts of the joints and transfer them towards the diaphysis, which is a stronger and more resistant bone tissue. In this way it prevents the joint complex from being overloaded.
Injuries
Lesions of the metaphyses are especially important during the growth period. This is due to its relationship to the growth plate.
About 30% of fractures in growing individuals involve the growth plate and, from this percentage, it is extrapolated that 75% have a metaphysis injury.
Fractures of the metaphysis that involve damage to the growth plate are called Salter-Harris fractures. These are divided into five types, depending on the elements that are involved in the injury and the severity of it.
Types of Salter-Harris fractures. By SalterHarris.png: Dr Frank Gaillard (MBBS, FRANZCR) (http://www.frankgaillard.com). The original uploader was Benweatherhead at English Wikipedia.derivative work: Zerodamage - This file was derived from:, CC BY-SA 3.0, commons.wikimedia.org
This type of fracture occurs in very active children, usually athletes. The most common are called Salter type II; they are linear ruptures that partially separate the metaphysis and the growth plate of the epiphysis.
In some cases it is difficult to see them clearly on a conventional radiograph. The diagnosis is made by correlating the history with the physical examination and radiological findings.
Salter-Harris type II fracture. By Gilo1969 at English Wikipedia, CC BY 3.0, commons.wikimedia.org
Type II Salter fractures are easy to manage, with immobilization and rest, and do not interfere with the child's growth.
These lesions must be evaluated by a specialist, since when the timely diagnosis is not made, the patient can have repercussions on growth that are not reversible.
References
- Lorincz, C., Manske, SL, & Zernicke, R. (2009). Bone health: part 1, nutrition. Sports health. Taken from: ncbi.nlm.nih.gov
- Hairstyle, L; Garzón, D; Cárdenas, R. (2009). Biological process of epiphyseal development: appearance and formation of the secondary center of ossification. Cuban Journal of Orthopedics and Traumatology. Taken from: scielo.sld.cu
- Mirtz, T. A; Chandler, J. P; Eyers, CM (2011). The effects of physical activity on the epiphyseal growth plates: a review of the literature on normal physiology and clinical implications. Journal of clinical medicine research. Taken from: ncbi.nlm.nih.gov
- El Sayed, S. A; Nezwek, T. A; Varacallo, M. (2019). Physiology, Bone. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
- Garzón, D; Roa, M; Ramírez, AM (2008). Factors that influence endochondral growth: experiments and models. Cuban Journal of Orthopedics and Traumatology. Taken from: scielo.sld.cu
- Tanck, E; Hannink, G; Ruimerman, R; Buma, P; Burger, E. H; Huiskes, R. (2006). Cortical bone development under the growth plate is regulated by mechanical load transfer. Journal of anatomy. Taken from: ncbi.nlm.nih.gov
- Levine, R. H; Foris, L. A; Nezwek, TA (2019). Salter Harris Fractures. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov