Growth Plates in Children: A Parent's Complete Guide (Ages, Signs, and How to Support Them)

Growth plates are thin zones of cartilage tissue found near the ends of long bones in children and teens. Also called epiphyseal plates or physes, they are the active sites where bones grow in length. When a child reaches the end of puberty, these cartilage zones harden into solid bone and bone growth stops. This process is called growth plate closure.

If your child is still in their growing years, here is what every parent needs to understand about growth plates, what affects them, and what genuinely supports healthy bone development during this window.

What Are Growth Plates, Exactly?

A growth plate is a layer of developing cartilage tissue positioned near each end of a child's long bones. Unlike the hard, dense bone adults have, growth plate cartilage is softer and more flexible. This is what makes bones in children capable of lengthening during childhood and adolescence.

Every long bone in the body typically has two growth plates, one near each end. As the body produces new cartilage cells, older cells gradually harden into bone through a process called ossification. This continuous cycle is how bones get longer year after year.

The term "long bones" refers to bones that are longer than they are wide. These include:

• The femur (thigh bone)
• The tibia and fibula (lower leg bones)
• The radius and ulna (forearm bones)
• The humerus (upper arm bone)
• The bones in the hands, fingers, and feet

Growth plates are also present at the clavicle (collarbone), which is often the last bone in the body to fully close.

Where Are Growth Plates Located in a Child's Body?

Growth plates are present in every long bone. The ones most relevant to overall height are located at the ends of the femur (near the knee) and the tibia (just below the knee). Together, these two locations account for much of the height gained during the growing years.

Other significant locations include:

• The distal radius (just above the wrist)
• The proximal humerus (near the shoulder)
• The heel bone (calcaneal apophysis)
• The ends of the finger and toe bones

The growth plate locations most often injured in young athletes are the heel (Sever's disease), the knee (Osgood-Schlatter disease), and the elbow (Little League elbow). These injuries happen because the cartilage zone is softer than the surrounding tendons and ligaments, making it the weakest point under repeated stress.

When Do Growth Plates Close By Age?

Growth plates do not all close at the same time. Different bones close at different ages, and the timing varies between girls and boys due to differences in when puberty begins and ends. Girls generally close their growth plates earlier because they enter and complete puberty sooner than boys.

Here is a practical guide to when growth plates typically close by age and stage:

These are general averages. Individual variation is wide. Genetics, nutrition, and health status all influence timing. A pediatric orthopedic specialist can estimate remaining growth using a bone age X-ray, typically taken of the left hand and wrist, which shows how close the growth plates are to fusing.

How Can You Tell If Your Child's Growth Plates Are Still Open?

The only definitive answer comes from an X-ray. Pediatric orthopedic specialists use a bone age X-ray (left hand and wrist) or, in some cases, a pelvic X-ray to assess how much growth remains. This is a routine, low-radiation imaging tool your doctor can order if there is a clinical concern.

That said, there are reliable indicators a parent can observe without imaging:

Signs that growth plates are likely still open:

• The child has measurable height increases over the past 6 to 12 months
• Puberty is still in progress (not yet completed all stages of development)
• The child is within the typical age ranges above for their sex

Signs that growth plates may be closing or already closed:

• Height has not changed in 12 or more months
• The child has completed puberty
• Age is above 17 for boys or 15 for girls (though individual variation always applies)

If your child's growth seems to have slowed or stopped earlier than expected, a conversation with your pediatrician is a good first step. Growth chart monitoring at routine well visits is the standard first line of assessment.

Are Growth Plates Still Open at 25?

For most bones, no. The long bones that contribute to height, including the femur, tibia, and spine, typically close well before age 20. Most boys complete long bone growth plate closure by 17 to 19. Most girls are done by 15 to 17.

The exception is the clavicle (collarbone). The medial end of the clavicle is often cited as the last growth plate to close in the human body, and in some individuals this does not happen until the mid-twenties. However, this closure does not meaningfully affect height or overall bone length in the way the long bone plates do.

For practical purposes: if a young adult is 18 or older and has fully completed puberty, it is reasonable to assume most growth plates have fused. A doctor can confirm with imaging if there is a clinical concern.

What Happens If a Child Breaks a Growth Plate?

Growth plate fractures are more common in children than adults. Because the cartilage zone is softer than the surrounding tendons and ligaments, it is often the weakest point under stress. Published orthopedic estimates suggest that up to 30% of fractures in children involve the growth plate area.

Doctors classify growth plate fractures using the Salter-Harris system:

• Type I: Fracture through the growth plate only. Clean separation, no bone involved.
• Type II: Fracture through the growth plate and into the metaphysis (the wider part of the bone just above the plate). Most common.
• Type III: Fracture through the growth plate and into the epiphysis (the end of the bone).
• Type IV: Fracture through all three zones (epiphysis, growth plate, and metaphysis).
• Type V: Crush injury to the growth plate itself. Least common but most serious.

Most growth plate fractures, especially Types I and II, heal fully without affecting future bone development. More severe fractures may require surgical intervention and can occasionally result in a slight length discrepancy or angular change in the affected bone. If your child has significant pain or swelling near a joint after a fall or sports collision, have it evaluated. Growth plate injuries are often mistaken for sprains.

What Activities Are Safe When Growth Plates Are Open?

The short answer is: most activities are safe. Active play, organized sports, and age-appropriate exercise are genuinely beneficial during childhood and adolescence. Physical activity supports bone density, muscle strength, coordination, and overall development.

The risk area is overuse. Repetitive high-load movements performed without adequate rest can stress the growth plate over time. This is how conditions like Osgood-Schlatter disease (knee), Sever's disease (heel), and Little League elbow develop. They are not caused by activity itself, but by too much of one activity without sufficient recovery.

Practical guidelines for parents of active kids:

• Build in at least one rest day per week from sport-specific training
• Encourage rest between sports seasons where possible
• Watch for persistent pain near joints rather than general muscle soreness, and get it evaluated
• Be cautious about year-round single-sport specialization before age 12

What Nutrients Support Healthy Growth Plate Development?

This is the question most growth plate articles skip entirely. It is also one of the most practical things a parent can know.

Growth plates are cartilage that converts to bone through ossification. For this to work optimally, the body needs specific raw materials delivered in adequate amounts. When any of these nutrients are missing or low, the skeleton cannot build bone matrix as efficiently during the growth window. This is especially relevant for picky eaters, children with restricted diets, or kids who simply do not eat enough variety.

The six nutrients most directly tied to healthy bone development in children are:

Calcium is the primary mineral in bone. It forms the structural matrix of bone tissue as growth plates ossify. Children who avoid dairy or have low calcium intake are at a measurable disadvantage during these years.

Vitamin D3 enables the body to absorb calcium from food. Without adequate D3, a significant portion of the calcium a child consumes passes through without reaching bone tissue. Vitamin D insufficiency is common in children, particularly in northern climates and in kids with limited outdoor time.

Vitamin K2 MK-7 is the least well-known nutrient on this list. K2 acts as a transport protein that directs calcium specifically to bone and away from soft tissue. The MK-7 form is particularly effective because it stays biologically active in the body for up to 72 hours, compared to less than 24 hours for the more common MK-4 form. Most children's diets are very low in K2 because it is found primarily in fermented foods like natto, which most kids never eat.

Zinc is essential for collagen synthesis in bone. Collagen forms the structural scaffolding that calcium fills in during ossification. Low zinc intake is common in children with limited-variety diets who eat little meat or legumes.

Magnesium activates Vitamin D3. Without sufficient magnesium, the body cannot convert D3 into its active, usable form. This means even children who supplement with D3 may not benefit from it if magnesium is depleted. Most processed and packaged foods are low in magnesium.

Omega-3 DHA supports the health of osteoblasts (bone-building cells) and helps reduce low-grade inflammation that can interfere with normal bone formation. Most children's diets are DHA-poor unless oily fish is consumed several times per week, which is uncommon.

One underappreciated factor: most children's supplements contain added sugar. Sugar triggers an insulin response, and elevated insulin is associated with reduced absorption of fat-soluble nutrients including K2 and D3. A supplement that includes the right nutrients but delivers them alongside a sugar spike is working against itself. Choosing a zero-sugar formula matters more than most parents realize.

"My son is 11 and I started giving him Tallori 3 months ago. I've noticed he's been eating better overall. The gummies taste great and he actually reminds ME to give them to him." — Amanda R. (Loox verified review)

What Can Parents Do During the Growth Window?

The growth window is exactly that: a window. Once growth plates fuse, the skeleton is set. The decisions made during the growing years, around nutrition, sleep, and activity, have a real bearing on how well that window is used.

Here are the four areas where parents have the most leverage:

Protect sleep. The large majority of growth hormone is released in pulses during deep sleep. Sleep is not passive during the growing years. It is when the body does a significant portion of its skeletal work. Consistent, quality sleep is one of the highest-leverage factors during the growth window.

Support the nutritional foundation. This does not require a perfect diet. It means identifying the most common gaps, typically D3, K2, zinc, and magnesium, and making sure they are covered. For picky eaters or children with restricted diets, a targeted supplement with a complete, zero-sugar formula can help fill those gaps consistently.

Manage activity load smartly. Encourage sport participation and physical activity. Monitor for overuse patterns. A sports medicine physician or pediatric orthopedist can advise on appropriate training volumes for young athletes, particularly those who specialize early or train year-round.

Use growth chart monitoring. Your child's pediatrician tracks height at every well visit. If growth has significantly slowed or stalled, that conversation is worth having. In some cases, nutritional deficiencies or other treatable factors may be contributing.

You can read more in our complete guide to supporting your child's height potential during the growing years.