Do adults have epiphyseal plates, or are they a thing of the past?

By early adulthood, the process of longitudinal bone growth has come to a halt. This is due to a crucial anatomical change, but do adults have epiphyseal plates? The authoritative answer is no; in adults, the cartilaginous growth plates have fused and are replaced by a bony landmark known as the epiphyseal line.

Quick Summary

Adults do not have epiphyseal plates, the cartilage-rich areas responsible for bone lengthening during childhood and adolescence. Instead, these growth plates fully ossify, or turn into bone, leaving behind a faint epiphyseal line that marks where the growth once occurred.

Key Points

• Growth Ends in Adulthood: Adults do not possess epiphyseal plates, as longitudinal bone growth concludes by early adulthood.

• Cartilage Becomes Bone: The epiphyseal plate, a region of hyaline cartilage, fully ossifies and is replaced by solid bone tissue in adulthood.

• Epiphyseal Line is the Remnant: The remnant of the closed growth plate is known as the epiphyseal line, visible as a thin, bony landmark on a long bone.

• Growth Plate Closure Varies: The timing of growth plate closure differs between genders, typically occurring earlier in females than in males.

• Bone Remodeling Continues: Even after growth plates close, bones remain living tissue that continually remodels and can grow in thickness throughout life.

• Injuries Differ in Children: The presence of weaker, active growth plates makes children susceptible to different types of fractures than adults.

• Hormones Signal Closure: The surge of sex hormones during puberty is the primary signal that triggers the final closure of the growth plates.

What are epiphyseal plates?

The epiphyseal plate, also known as the growth plate, is a crucial area of hyaline cartilage located in the metaphysis of long bones in children and adolescents. These plates are essential for bone lengthening and increasing a child's height. The growth process involves chondrocytes that multiply and mature, and osteoblasts that replace the degenerating cartilage with bone tissue in a process called endochondral ossification. This cycle continues throughout growth, pushing the epiphysis away from the diaphysis and lengthening the bone.

The closure of the epiphyseal plates

Skeletal maturity is reached when the epiphyseal plates close. This closure is triggered by hormonal changes during puberty, particularly an increase in sex steroid hormones. The cartilage production slows, and the remaining cartilage is replaced by bone, causing the epiphysis and diaphysis to fuse. Once fused, longitudinal bone growth stops, and the epiphyseal plate is replaced by a thinner bony line called the epiphyseal line.

Timeline of growth plate fusion

The timing of epiphyseal closure is variable and generally occurs earlier in females than in males. Most epiphyseal plates close between the ages of 13 and 15 in girls and 15 and 17 in boys. Genetic factors, nutrition, and overall health can influence this timeline.

Epiphyseal line vs. epiphyseal plate: A comparative view

These two structures represent different stages of bone development.

Feature	Epiphyseal Plate (in children)	Epiphyseal Line (in adults)
Composition	Hyaline cartilage	Osseous (bone) tissue
Function	Responsible for longitudinal bone growth	Marks the location where the growth plate used to be
Location	Between the epiphysis and diaphysis of a long bone	A remnant, or fusion line, between the epiphysis and diaphysis
Appearance	Visible on X-ray as a radiolucent (darker) line due to being cartilage	Visible on X-ray as a radiopaque (lighter), solid line of bone
Active state	Biologically active with ongoing cell division	Biologically inactive; growth has ceased

What happens after the plates close?

While bones stop lengthening, they continue to undergo remodeling throughout life, where old bone is replaced by new bone tissue. Bones can also grow thicker through appositional growth, especially with weight-bearing activities. This continued bone health is particularly important for seniors, as bone density can decline with age, potentially leading to osteoporosis. Proper nutrition with calcium and Vitamin D, along with exercise, is essential for maintaining strong bones in adulthood.

The clinical relevance of growth plates

Growth plates are weaker than surrounding bone and ligaments, making them susceptible to injury in children. Fractures in this area can affect bone growth if not treated properly. In adults, the fused epiphyseal line is visible on imaging and indicates skeletal maturity.

Conclusion: The growth plate is a youthful memory

In summary, adults do not have epiphyseal plates. These growth plates from childhood are replaced by epiphyseal lines, signifying the end of bone lengthening. However, bone remains a dynamic tissue throughout life, requiring care to maintain strength and integrity.

For more detailed information on bone anatomy and the human skeleton, visit AnatomyZone.

Frequently Asked Questions

What is the difference between an epiphyseal plate and an epiphyseal line?

The epiphyseal plate is a layer of hyaline cartilage in children and adolescents that facilitates bone lengthening. The epiphyseal line is the bony remnant that replaces the growth plate once a person reaches skeletal maturity and has stopped growing in height.

At what age do epiphyseal plates close?

Epiphyseal plates typically close during late adolescence. For females, this usually occurs between ages 13–15, and for males, it's generally between ages 15–17, though the exact timing can vary by individual and specific bone.

Can an adult's bone grow longer?

No, an adult's bones cannot grow longer. Once the epiphyseal plates have fused and become epiphyseal lines, longitudinal bone growth ceases. However, adult bones can still grow in diameter in a process called appositional growth.

Why is it important to know that adults have epiphyseal lines and not plates?

Knowing that adults have epiphyseal lines confirms that their growth period is over and provides a reference point for radiologists and orthopedists. In children, the presence of vulnerable growth plates significantly affects how bone injuries are diagnosed and treated to ensure proper healing.

What is endochondral ossification?

Endochondral ossification is the process by which cartilage is converted into bone. This is the primary mechanism for the longitudinal growth of long bones in a child's epiphyseal plate, but it is no longer active in the fused bones of an adult.

Does adult bone remodeling have anything to do with epiphyseal plates?

No, adult bone remodeling is a separate process. While it keeps bones strong and healthy by replacing old tissue with new, it occurs throughout the bone and does not involve the closed epiphyseal plates, which are no longer functional.

What happens if a child injures their growth plate?

Since growth plates are weaker than other parts of the bone, they are more susceptible to injury. A fracture in this area can be serious and, if not treated correctly, could disrupt the bone's normal growth, potentially leading to future deformities or limb length discrepancies.