Growth Plates: What They Are and When They Close

What growth plates are and where they sit

Growth plates are areas of cartilage near the ends of bones, says the American Academy of Orthopaedic Surgeons. Most long bones have at least two, one near each end. Each one sits between the wide part of the bone shaft (the metaphysis) and the end of the bone (the epiphysis).

A bone does not grow from its middle outward. It grows at each end, around the growth plate. A review in Orthopaedics and Trauma calls the growth plate a highly ordered structure made of discrete layers.

When a child is fully grown, the plates harden into solid bone. Until then, they are the last part of a child’s bones to harden. That makes them particularly vulnerable to injury.

When do growth plates close

There is no single age. Growth plates close as puberty finishes, and puberty timing differs from child to child. The best data we found is an MRI study of 958 healthy people aged 14.0 to 21.5 years. It checked growth plates in the wrist, knee and ankle.

Girls and boys

	At least 50% fused	At least 90% fused	All closed at every site tested
Girls	Ages 14 to 17	Ages 15 to 18	Age 19 and older
Boys	Ages 15 to 18	Ages 17 to 20	By age 21

The authors found that complete fusion happens about 2 years earlier in girls than in boys. For more on boys, see when do guys stop growing. For the fast phase before plates close, see our guide to the growth spurt.

One limit to keep in mind: the study started at age 14. It says nothing about plates that closed earlier.

Why the closing age varies

In the same study, closing was linked to sex, pubertal development and BMI. Regular physical activity did not predict it.

The American Academy of Pediatrics adds two points. Children who start puberty earlier often have an earlier growth spurt. And extra body weight can sometimes make bones mature faster, which may lead to growth stopping sooner.

Why plates close at different times

Growth plates do not all close together. In the MRI study, they closed in this order:

1. The heel bone (calcaneus)
2. The lower end of the shin bone (distal tibia)
3. The upper end of the shin bone and the lower end of the thigh bone, near the knee
4. The wrist end of the forearm bone (distal radius), last of the sites tested

Can anything keep growth plates open?

Not based on any evidence we found. We found no study showing that a food, exercise or supplement keeps growth plates open or delays closing. Some posts online say otherwise. The MRI study found that regular activity did not predict closure.

Once the plates close, the AAP says a child can no longer grow taller. Good nutrition supports normal growth, and poor nutrition can slow it, the AAP notes. Nothing reopens a closed plate. Our guide on how to grow taller covers what the evidence does and does not show.

How doctors check growth plates and bone age

A review in Frontiers in Pediatrics defines bone age as the age, in years, that matches how mature the bones are. The most used image is an X-ray of the hand and wrist. The AAP says that X-ray may show how much growth your child has left.

A doctor compares the X-ray with a set of reference images, such as the Greulich and Pyle atlas. Current height plus bone age is the most accurate way to predict adult height, according to the AAP.

What to know	Detail
What is X-rayed	The hand and wrist, by convention the left hand
Reader variation	In one study with three readers, results varied by about 0.96 years with Greulich and Pyle and 0.74 years with the Tanner and Whitehouse method
Greulich and Pyle limits	Cannot be used under age 6. The review says it does not apply to African or Asian populations.
Parent height	About 60% to 70% of height differences come from parents’ heights. The parent-based formula can be off by about 4 inches.

A bone age number is an estimate, not a promise. Your pediatrician decides whether your child needs the test.

Growth plate injuries in kids and young athletes

Fractures

A growth plate fracture can come from one event, such as a fall or a car crash, or from repeated stress. The AAOS says they often happen in football, basketball and gymnastics, and also while biking, sledding, skiing or skateboarding.

They happen twice as often in boys as in girls, because girls finish growing earlier. Doctors sort them into Salter-Harris types:

• Type I: the break runs through the bone at the growth plate.
• Type II: the break crosses part of the plate and cracks into the bone shaft. This is the most common type.
• Type III: the break crosses part of the plate and breaks off a piece of the bone end.
• Type IV: the break goes through the shaft, the plate and the bone end.
• Type V: a crushing injury to the plate. It is rare.

Overuse injuries

Growth plates are weaker than nearby ligaments and tendons. Repeated stress can hurt the plate without any single fall. If an X-ray shows a stress reaction, the AAOS says treatment means stopping the aggravating activity for 2 to 3 months.

Condition	Where it hurts	Good to know
Sever’s disease	Heel	One of the most common causes of heel pain in children
Osgood-Schlatter disease	Front of the knee	Symptoms usually end after the growth spurt, around age 14 for girls and 16 for boys
Little Leaguer’s elbow	Inner elbow	Seen in young throwers
Wrist growth plate stress reaction	Wrist	Seen in gymnasts from repeated wrist loading

Signs to call a doctor about

The AAOS lists these signs of a growth plate fracture:

• Pain that does not go away
• A limb that looks bent or out of shape
• Not being able to move the limb or put weight on it
• A limp that does not go away
• Swelling, warmth and tenderness near a joint

Doctors use X-rays, but some fractures do not show up on them. The physical exam is key. Many fractures heal well in a cast, and serious problems are rare. Rarely, a bony bridge forms across the break and can stunt growth of that bone or curve it. The AAOS advises follow-up visits for at least a year after the injury.

Prevention checklist

• Limit the number of teams your child plays on in one season.
• Do not let your child play one sport all year.
• Get medical clearance before your child returns to a sport after an injury.

These tips come from the AAOS overuse guide.

What growing bones need

Food and play support healthy bones. Eating more or adding a supplement does not delay when growth plates close or add height beyond normal growth. Poor nutrition, though, can slow growth, the AAP says. The NIH says bone mass peaks by the mid to late 20s, so the childhood years matter for bone health. Calcium and vitamin D are the two nutrients to watch.

Age	Calcium a day	Calcium upper limit	Vitamin D a day	Vitamin D upper limit
4 to 8	1,000 mg	2,500 mg	600 IU	3,000 IU
9 to 13	1,300 mg	3,000 mg	600 IU	4,000 IU
14 to 18	1,300 mg	3,000 mg	600 IU	4,000 IU

Many children and teens aged 4 to 18 get less calcium than recommended, according to the Office of Dietary Supplements. The NIH also notes that many teens do not get enough vitamin D. Too little of either can lead to rickets, a disease that makes children’s bones soft and weak.

Food first

• Calcium: milk, yogurt and cheese are the main sources. One 8-ounce glass of milk has 300 mg. Canned sardines and salmon with bones, kale, broccoli and bok choy also have calcium.
• Vitamin D: fatty fish such as salmon and trout. Almost all U.S. milk is fortified with about 3 mcg (120 IU) per cup. The body also makes vitamin D when bare skin is in the sun.
• Activity: weight-bearing and resistance exercise is best for bones, says the NIH.

Sources for the food list: calcium, vitamin D and NIAMS.

If you are weighing a growth gummy, see our pick below. The NIH says to talk to your child’s health care provider if you are thinking about giving a supplement. For more, read vitamins for kids and how to read a supplement label. Curious about dairy? See does milk make you taller.

When to talk to your pediatrician

Call your pediatrician if:

• Your child’s growth seems to slow down or stop on the growth chart.
• You see signs of early puberty. The AAP says breast development before age 8 in girls, or other signs of unusually early puberty, should be checked by a doctor.
• Your child has limb pain after a fall, a limp, or swelling near a joint.

The AAP also notes that too few calories, protein or key nutrients can slow growth. A doctor can look at the whole picture. A supplement is not a substitute for that visit.

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