Which Growth Plates Close First? A Timeline

Growth plates don’t all shut at once. They close in a rough sequence across the skeleton, from some elbow plates near the start of the teens to a few that wait until the early twenties. Height growth ends when the last plates in the long leg bones close, so the closing order is really a countdown to adult height. The trigger for that countdown is the same in boys and girls, the hormone estrogen, and the timing differs mainly because girls reach it sooner.1Frontiers in Endocrinology. Factors affecting prepubertal and pubertal bone age progression

What a Growth Plate Is and What Closing Means

A growth plate is a thin disc of cartilage near each end of a long bone. New cells are made there and then turned into bone, which is how the bone gets longer.2Folia Histochemica et Cytobiololgica. Morphology and physiology of the epiphyseal growth plate On a child’s X-ray the plate shows up as a dark line near the end of the bone, because cartilage doesn’t show up the way bone does.

That line is not a crack or a break, and a doctor will often compare the other limb, because the same normal line appears in the same spot on both sides.

Closing is a slow running-out, not a sudden switch. In early puberty the cartilage cells can keep multiplying, but by late puberty that ability fades with age.3PubMed Central. Pubertal growth and epiphyseal fusion When multiplying stops completely, lengthwise growth stops and that bone has reached its adult length.4PubMed Central. Pubertal growth and epiphyseal fusion The plate is then replaced by bone, joining the end of the bone to its shaft.5American Journal of Physical Anthropology. Short Adolescence in Early Hominids: Infantile and Adolescent Growth of the Human Femur Exactly how the last cartilage cells disappear is still unsettled. Ideas include cells dying off, being starved of oxygen, or turning into bone cells.6PubMed Central. The growth plate: a physiologic overview

On an X-ray, an open plate shows a clear gap line. A closing plate shows the gap partly bridged by bone, and as it closes the line gets thinner and then fades. A closed plate may leave a faint scar line for years, which is not an open plate. Different plates can also be at different stages in the same child at the same time.

Each bone stops lengthening when its own plates close, and height depends mostly on the leg bones and spine. A closed elbow plate says little about how much height is left, which is why the order matters more than any single plate.

The Order Growth Plates Close in, From First to Last

So a 13-year-old can legitimately have some elbow plates closed and one still open.

Even one joint follows a sequence. The bone centres around the elbow appear in a set order starting around age 1, 12Royal Children’s Hospital Melbourne. Ossification centres The first appears in infancy, and the others follow over the next decade. Because the order is reliable, a doctor reading a child’s elbow X-ray can tell a normal centre from a broken-off fragment.

The inner collarbone is the classic last-to-close plate. The final stage of its fusion is mostly seen only in people 18 and older.13PubMed. Ossification variation of the medial clavicular epiphysis in children, adolescents and young adults An open collarbone plate in a young adult is normal and doesn’t mean they will keep getting taller.

Humans vary, so the ages in any chart are ranges, not a cutoff. Early or late puberty shifts the whole timeline, and a healthy teen can sit a year or two either side.14PubMed. Heterochrony and post-natal growth in mammals–an examination of growth plates in limbs

The knee matters most for height. It holds two of the most active plates in the body, one at the end of each leg bone. Once both close, leg growth is essentially done, and the spine adds only a little afterwards.

Why Girls Finish About Two Years Before Boys

Girls’ growth plates close about 2 years before boys’.15PubMed Central. A cross-sectional magnetic resonance imaging study of factors influencing growth plate closure in adolescents and young adults The result is that boys often keep growing into their late teens while most girls have stopped.

Many people assume testosterone alone ends male growth. Estrogen is actually the essential signal in both sexes, and it is needed to close growth plates in young men as well as women.16PubMed Central. Effects of estrogen on growth plate senescence and epiphyseal fusion It speeds the use-up of the reserve of resting cartilage cells, exhausting the supply.17PubMed Central. The growth plate: a physiologic overview High estrogen in late puberty is what finally closes the plates and ends growth.18PubMed Central. The role of estrogen receptor-α and its activation function-1 for growth plate closure in female mice In boys, much of this estrogen is made from testosterone in the body. Testosterone still drives the growth spurt itself, and boys close later mainly because puberty starts and finishes later.

For girls, the first period is a useful landmark. Most of a girl’s fastest growth comes before it. Growth slows afterwards as estrogen rises, and most remaining growth comes over the next couple of years.

Hormones and Conditions That Shift the Timeline

Growth hormone, thyroid hormone, estrogen and androgens all speed bone maturing.19Frontiers in Endocrinology. Factors affecting prepubertal and pubertal bone age progression Puberty that starts very early brings estrogen early and can close plates early, cutting adult height.

Signs of early puberty worth raising with a doctor include breast development in girls before about age 8, testicle growth or body hair in boys before about age 9, and a sudden growth spurt well ahead of classmates. Early checking matters because closed plates can’t reopen.

Treatment can buy time. Children with early puberty can be given medicines that switch off sex-hormone production and postpone plate closure.20PubMed Central. Growth plate closure and therapeutic interventions In early puberty this has added about 2 to 10 cm to adult height.21PubMed Central. Growth plate closure and therapeutic interventions In teens with short stature for no known cause, gains were smaller, about 1.7 to 6.7 cm.22PubMed Central. Growth plate closure and therapeutic interventions These treatments are decided by a specialist and aren’t something to seek for a typically growing child.

Some genetic conditions limit plate growth too. Certain gene changes that overactivate a growth signal, as in achondroplasia, slow bone growth at the plates.23PubMed Central. Mutant activated FGFR3 impairs endochondral bone growth by preventing SOX9 downregulation in differentiating chondrocytes

Supplements and stretching don’t keep plates open, and lifting weights with good supervision isn’t known to close them early. Sleep and nutrition support growth but don’t delay closure. Once a plate has fused, it cannot restart growth.

How a Doctor Tells Whether Growth Plates Are Still Open

Doctors usually X-ray the left hand and wrist and compare it to an atlas to estimate bone age, which is how mature the skeleton looks. A bone age behind real age often suggests more growth time left. The most common atlas covers bone ages up to about 19 years.24PubMed Central. Bone age assessment: comparative analysis of Greulich-Pyle and Tanner-Whitehouse 3 by pediatric radiologists and endocrinologists Another scoring system stops at about 15 for girls and 16.5 for boys, so it can’t rate an older teen.25PubMed Central. Bone age assessment: comparative analysis of Greulich-Pyle and Tanner-Whitehouse 3 by pediatric radiologists and endocrinologists

Bone age is an estimate. Two standard methods can disagree by up to about 2 years on the same X-ray.26PubMed Central. Bone age assessment: a large scale comparison of the Greulich and Pyle, and Tanner and Whitehouse (TW2) methods A single bone age is best treated as a rough guide, and trends over time tell more.

Doctors can also use bone age to predict adult height, combining it with current height and the parents’ heights. Predictions carry a margin of a few centimetres. Late bloomers with a young bone age often catch up, and it’s worth asking the doctor what the result means for remaining height.

Radiation-free options exist. Knee MRI can show whether the thigh and shin plates have matured without radiation.27PubMed Central. T2-weighted spoiled gradient echo MRI for forensic age estimation: a study on knee growth plates

Growth Plate Injuries and Overuse in Young Athletes

Breaks through a growth plate are common in children because the cartilage is weaker than the bone around it. Torn tissue can fold into the gap and block normal healing.28Radsource. Salter-Harris Fractures Part of the plate can then close early while the rest keeps growing, bending the plate.29PubMed. Premature partial closure and other deformities of the growth plate: MR imaging and three-dimensional modeling A bone can end up growing crooked or short, which is why follow-up X-rays matter. Doctors may schedule checks for a year or more.

Timing changes the risk. Plates near closure have little growth left to lose, while injuries in younger children carry more risk of uneven growth. The elbow and knee timelines above help gauge this.

Repeated stress can also harm a plate. Repeated weight-bearing on bent-back wrists, as in gymnastics, stresses the wrist growth plate.30PubMed Central. GYMNAST’S WRIST: A RETROSPECTIVE ANALYSIS OF DESCRIPTIVE EPIDEMIOLOGY, CLINICAL & RADIOLOGIC FEATURES, TREATMENT & OUTCOMES In a gymnast with wrist pain, widening of the plate on X-ray points to a stress injury rather than a normal adaptation.31PubMed. Stress changes of the distal radial growth plate. A radiographic survey and review of the literature It can slow or halt growth at the wrist and unbalance the forearm bones.32PubMed. Stress changes of the distal radial growth plate. A radiographic survey and review of the literature Ongoing wrist pain in a young gymnast deserves rest and an exam.

See a doctor for pain right over the end of a bone near a joint, for swelling or refusal to use the limb after a fall, or for pain that returns with every practice. A “sprain” in a child may turn out to be a growth plate injury.

Why Doctors Track Closure for Leg Length and Treatment

For unequal leg lengths, surgeons can close a growth plate on the longer leg on purpose, timed using predicted remaining growth.33PubMed Central. Evaluation of a Mobile Application for Multiplier Method Growth and Epiphysiodesis Timing Predictions The team measures the difference and the child’s growth rate, predicts how much growth each plate has left, and closes the longer leg’s plate when the remaining growth matches the gap. Too late means not enough correction, and too early can overcorrect, so timing is everything.

Radiation treatment in childhood can damage growth plates, so cancer teams map them to limit harm.34Elsevier / PubMed Central. A Road Map for Important Centers of Growth in the Pediatric Skeleton to Consider During Radiation Therapy and Associated Clinical Correlates of Radiation-Induced Growth Toxicity Afterwards, bones in the treated area may grow less, and regular height and limb checks are part of follow-up. Families should ask which plates were in the treatment field.

Do Human Growth Plates Close Late Compared With Animals

Chimpanzees’ thigh bones finish growing at 11 to 12, versus 16 to 18 in humans.35American Journal of Physical Anthropology. Short Adolescence in Early Hominids: Infantile and Adolescent Growth of the Human Femur Relative to lifespan, humans close plates late, while most other animals close them early.36PubMed. Review of growth plate closure compared with age at sexual maturity and lifespan in laboratory animals Forensic experts use which plates have fused to estimate a young person’s age.37PubMed Central. Estimation of age in forensic anthropology: historical perspective and recent methodological advances