Growth Plate – Function, Injuries and Disorders
The growth plate is a layer of cartilage near the ends of long bones in children and adolescents that regulates bone length growth.
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The growth plate is a layer of cartilage near the ends of long bones in children and adolescents that regulates bone length growth.
What Is the Growth Plate?
The growth plate, also known medically as the epiphyseal plate or physis, is a specialized zone of cartilage located between the shaft (diaphysis) and the ends (epiphyses) of long bones. It is present exclusively in children and adolescents and is the primary structure responsible for the longitudinal growth of the skeleton. Once growth is complete, the growth plate is fully replaced by bone tissue in a process known as epiphyseal closure.
Structure and Location
Growth plates are found in the long bones of the body, including the femur (thigh bone), tibia (shin bone), humerus (upper arm bone), and the bones of the hands and feet. Anatomically, the growth plate consists of several layers of specialized cartilage cells (chondrocytes) organized into distinct zones:
- Resting zone: Contains stem cells that supply precursor cells for growth.
- Proliferative zone: Cartilage cells actively divide and arrange themselves in columnar rows.
- Hypertrophic zone: Cells enlarge significantly before undergoing cell death.
- Ossification zone: New bone tissue forms and replaces the cartilage.
Function
The primary function of the growth plate is to drive the longitudinal growth of bones. Through continuous cell division and subsequent ossification, the bone grows in length from the plate outward. This process is regulated by several hormones, including:
- Growth hormone (somatotropin): Stimulates cell division in the proliferative zone.
- Insulin-like Growth Factor 1 (IGF-1): Amplifies the effects of growth hormone directly within the plate.
- Thyroid hormones: Support proper bone development and maturation.
- Sex hormones (estrogen, testosterone): Initially promote growth and ultimately trigger epiphyseal closure.
Epiphyseal Closure
Epiphyseal closure refers to the process by which the growth plate is completely replaced by bone at the end of puberty. After closure, no further increase in bone length is possible. The timing of closure varies by bone and by sex -- in girls, it typically occurs between ages 14 and 16, while in boys it generally occurs between ages 16 and 18.
Clinical Significance
Because the growth plate is composed of soft cartilage, it is mechanically weaker than the surrounding bone tissue. This makes it particularly vulnerable to injury in children and adolescents.
Growth Plate Fractures
Injuries to the growth plate, known as epiphyseal plate fractures, are common in children and account for approximately 15 to 30 percent of all fractures in childhood. They are classified according to the internationally recognized Salter-Harris classification, which divides injuries into five types based on the location and extent of damage. Prompt and accurate treatment is essential, as growth plate injuries can lead to growth disturbances, angular deformities, or premature epiphyseal closure.
Diseases Affecting the Growth Plate
In addition to fractures, several conditions can affect the growth plate:
- Blount disease: A growth disorder of the medial tibial growth plate leading to bowleg deformity.
- Slipped capital femoral epiphysis (SCFE): A displacement of the femoral head relative to the neck of the femur, most common in overweight adolescents.
- Osteochondrosis: Disruption of blood supply to the growth plate, potentially causing local bone necrosis (e.g., Perthes disease).
- Rickets: A mineralization disorder caused by vitamin D deficiency that directly impairs growth plate development.
Diagnosis
The growth plate can be assessed using various imaging methods:
- X-ray: The standard method for evaluating growth plate injuries and determining bone age.
- MRI (Magnetic Resonance Imaging): Particularly useful for visualizing cartilage structures and detecting early damage.
- Ultrasound: Can be used as a supplementary tool, especially in infants and young children.
Treatment and Prevention
Treatment of growth plate injuries depends on the type and severity of the injury. Minor injuries (Salter-Harris types I and II) are often managed conservatively with immobilization. More severe injuries (types III to V) frequently require surgical intervention to restore the precise anatomical position of the plate and prevent growth complications. Regular follow-up examinations are important to monitor continued bone development.
References
- Salter RB, Harris WR. Injuries Involving the Epiphyseal Plate. Journal of Bone and Joint Surgery. 1963;45(3):587-622.
- Kronenberg HM. Developmental regulation of the growth plate. Nature. 2003;423(6937):332-336.
- Rockwood CA, Wilkins KE, Beaty JH. Fractures in Children. 8th edition. Philadelphia: Wolters Kluwer; 2015.
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Related search terms: Growth Plate + Growth Plates + Epiphyseal Plate + Epiphyseal Plates + Physis