por What is the metaphysis?
The metaphysis It 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 that are in a period of growth, the metaphysis is separated from the epiphysis by a transitional zone called growth platewhich allows bones to lengthen.
Once bone development ends, around 18 years of age for women and 21 years of age for men, the growth plate calcifies and the metaphysis permanently joins the epiphysis. This union is known as epiphyseal line.
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 torrent.
The metaphysis area is richly vascularized and these blood vessels are responsible for irrigating the growth plate that is located near it.
When fracture of the metaphysis occurs, the growth plate may be involved. This type of injury occurs in child athletes 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 lesion.
Histology
The 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 long bones. During growth it is separated from the epiphysis by a specialized cellular cartilage, which is called the growth plate.
In large bones such as the femur, tibia or radius, there are two metaphyses. One at the top, or proximal, and one at the 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 of the trabecular or spongy type. This type of tissue supports rebound impact well and transfers the vibrations of these blows to hard or compact bone tissue. It also has an architecture consisting of small bony partitions within which the bone marrow is found.
Within the bone marrow, blood cells are formed 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 will form the bones begin to differentiate from the 4th week of gestation, however, it is not until the 8th week that an organized formation of what will be the skeleton can be recognized.
Long bones originate between the 9th and 10th week and their process begins with the formation of cartilaginous tissue around which cells that differentiate into osteocytes, or bone cells, are grouped.
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 cartilaginous tissue forms at its junction end with the metaphysis that prevents calcification and adhesion between these parts.
The cartilage found in this area is a specialized tissue and has the property of elongating with growth.
In long bones, the differentiation between the metaphysis and the diaphysis can be clearly observed through a conventional radiological study.
When the child is born, its skeleton is completely formed and the long bones present these sections of cartilage that will allow growth.
functions
During the growth period, the bones are not completely calcified. This means that there are areas that are maintained with a tissue that is softer and more elastic than bone, which allows it to lengthen.
Between the epiphyses and metaphyses is this tissue called growth plate either 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 irrigating this area.
Irrigation is provided 1) intraosseously, through the channels formed inside the spongy tissue, 2) and extraosseously, through the blood vessels found 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 injures the epiphysis.
Another important function of the metaphysis is to absorb the impacts of the joints and transfer them to the diaphysis, which is a stronger and more resistant bone tissue. In this way it prevents the joint complex from being overloaded.
injuries
Metaphyseal lesions are especially important during the growth period. This is due to its relationship with the growth plate.
About 30% of fractures in growing individuals involve the growth plate and, of this percentage, it is extra that 75% have metaphyseal injury.
Fractures of the metaphysis that involve injury 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 its severity.
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 questioning with the physical examination and radiological findings.
Salter type II fractures are easy to manage, with immobilization and rest, and do not interfere with the growth of the child.
These lesions should be evaluated by a specialist, since when the timely diagnosis is not made, the patient may have repercussions on growth that are not reversible.