What Is the Growth Plate?
The growth plate, also known as the epiphyseal plate or
physis, is the area of growing tissue near the end of the long bones in
children and adolescents. Each long bone has at least two growth plates:
one at each end. The growth plate determines the future length and shape
of the mature bone. When growth is complete--sometime during
adolescence--the growth plates close and are replaced by solid bone.
Who Gets Growth Plate Injuries?
These injuries occur in children and adolescents. The
growth plate is the weakest area of the growing skeleton, weaker than
the nearby ligaments and tendons that connect bones to other bones and
muscles. In a growing child, a serious injury to a joint is more likely
to damage a growth plate than the ligaments that stabilize the joint. An
injury that would cause a sprain in an adult can be associated with a
growth plate injury in a child.
Injuries to the growth plate are fractures. They comprise
15 percent of all childhood fractures. They occur twice as often in boys
as in girls, with the greatest incidence among 14- to 16-year-old boys
and 11- to 13-year-old girls. Older girls experience these fractures
less often because their bodies mature at an earlier age than boys. As a
result, their bones finish growing sooner, and their growth plates are
replaced by stronger, solid bone.
Approximately half of all growth plate injuries occur in
the lower end of the outer bone of the forearm (radius) at the wrist.
These injuries also occur frequently in the lower bones of the leg
(tibia and fibula). They can also occur in the upper leg bone (femur) or
in the ankle, foot, or hip bone.
What Causes Growth Plate Injuries?
While growth plate injuries are caused by an acute event,
such as a fall or a blow to a limb, chronic injuries can also result
from overuse. For example, a gymnast who practices for hours on the
uneven bars, a long-distance runner, or a baseball pitcher perfecting
his curve ball can all have growth plate injuries.
In one large study of growth plate injuries in children,
the majority resulted from a fall, usually while running or playing on
furniture or playground equipment. Competitive sports, such as football,
basketball, softball, track and field, and gymnastics, accounted for
one-third of all injuries. Recreational activities, such as biking,
sledding, skiing, and skateboarding, accounted for one-fifth of all
growth plate fractures, while car, motorcycle, and all-terrain-vehicle
accidents accounted for only a small percentage of fractures involving
the growth plate.
Whether an injury is acute or due to overuse, a child who
has pain that persists or affects athletic performance or the ability to
move or put pressure on a limb should be examined by a doctor. A child
should never be allowed or expected to "work through the pain."
Children who participate in athletic activity often
experience some discomfort as they practice new movements. Some aches
and pains can be expected, but a child’s complaints always deserve
careful attention. Some injuries, if left untreated, can cause permanent
damage and interfere with proper growth of the involved limb.
Although many growth plate injuries are caused by
accidents that occur during play or athletic activity, growth plates are
also susceptible to other disorders, such as bone infection, that can
alter their normal growth and development.
Additional Reasons for Growth Plate Injuries
- Child abuse can be a cause of skeletal injuries, especially in
very young children, who still have years of bone growth remaining.
One study reported that half of all fractures due to child abuse were
found in children younger than age 1, whereas only 2 percent of
accidental fractures occurred in this age group.
- Injury from extreme cold (for example, frostbite) can also damage
the growth plate in children and result in short, stubby fingers or
premature degenerative arthritis.
- Radiation, which is used to treat certain cancers in children, can
damage the growth plate. Moreover, a recent study has suggested that
chemotherapy given for childhood cancers may also negatively affect
bone growth. The same is true of the prolonged use of steroids for
rheumatoid arthritis.
- Children with certain neurological disorders that result in
sensory deficit or muscular imbalance are prone to growth plate
fractures, especially at the ankle and knee. Similar types of injury
are seen in children who are born with insensitivity to pain.
- The growth plates are the site of many inherited disorders that
affect the musculoskeletal system. Scientists are just beginning to
understand the genes and gene mutations involved in skeletal
formation, growth, and development. This new information is raising
hopes for improving treatment of children who are born with poorly
formed or improperly functioning growth plates.
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Signs That Require a Visit to the
Doctor
- Inability to continue play because of pain following an
acute or sudden injury
- Decreased ability to play over the long term because of
persistent pain following a previous injury
- Visible deformity of the child’s arms or legs
- Severe pain from acute injuries that prevent the use of an
arm or leg.
Adapted from Play It Safe, a Guide
to Safety for Young Athletes with permission of the American
Academy of Orthopaedic Surgeons. |
How Are Growth Plate Fractures
Diagnosed?
After learning how the injury occurred and examining the
child, the doctor will use x rays to determine the type of fracture and
decide on a treatment plan. Because growth plates have not yet hardened
into solid bone, they don’t show on x rays. Instead, they appear as gaps
between the shaft of a long bone, called the metaphysis, and the end of
the bone, called the epiphysis. Because injuries to the growth plate may
be hard to see on x ray, an x ray of the noninjured side of the body may
be taken so the two sides can be compared. Magnetic resonance imaging
(MRI), which is another way of looking at bone, provides useful
information on the appearance of the growth plate. In some cases, other
diagnostic tests, such as computed tomography (CT) or ultrasound, will
be used.
Adapted from Disorders and Injuries
of the Musculoskeletal System, 3rd Edition. Robert B. Salter,
Baltimore, Williams and Wilkins, 1999. Used with the author's
permission. |
Since the 1960’s, the Salter-Harris classification, which
divides most growth plate fractures into five categories based on the
type of damage, has been the standard. The categories are as
follows:
Type I
The epiphysis is completely separated from the end of the
bone or the metaphysis, through the deep layer of the growth plate. The
growth plate remains attached to the epiphysis. The doctor has to put
the fracture back into place if it is significantly displaced. Type I
injuries generally require a cast to keep the fracture in place as it
heals. Unless there is damage to the blood supply to the growth plate,
the likelihood that the bone will grow normally is excellent.
Type II
This is the most common type of growth plate fracture. The
epiphysis, together with the growth plate, is separated from the
metaphysis. Like type I fractures, type II fractures typically have to
be put back into place and immobilized.
Type III
This fracture occurs only rarely, usually at the lower end
of the tibia, one of the long bones of the lower leg. It happens when a
fracture runs completely through the epiphysis and separates part of the
epiphysis and growth plate from the metaphysis. Surgery is sometimes
necessary to restore the joint surface to normal. The outlook or
prognosis for growth is good if the blood supply to the separated
portion of the epiphysis is still intact and if the fracture is not
displaced.
Type IV
This fracture runs through the epiphysis, across the
growth plate, and into the metaphysis. Surgery is needed to restore the
joint surface to normal and to perfectly align the growth plate. Unless
perfect alignment is achieved and maintained during healing, prognosis
for growth is poor. This injury occurs most commonly at the end of the
humerus (the upper arm bone) near the elbow.
Type V
This uncommon injury occurs when the end of the bone is
crushed and the growth plate is compressed. It is most likely to occur
at the knee or ankle. Prognosis is poor, since premature stunting of
growth is almost inevitable.
A newer classification, called the Peterson
classification, adds a type VI fracture, in which a portion of the
epiphysis, growth plate, and metaphysis is missing. This usually occurs
with an open wound or compound fracture, often involving lawnmowers,
farm machinery, snowmobiles, or gunshot wounds. All type VI fractures
require surgery, and most will require later reconstructive or
corrective surgery. Bone growth is almost always stunted.
What Kind of Doctor Treats Growth Plate
Injuries?
For all but the simplest injuries, the doctor may
recommend that the injury be treated by an orthopaedic surgeon (a doctor
who specializes in bone and joint problems in children and adults). Some
problems may require the services of a pediatric orthopaedic surgeon,
who specializes in injuries and musculoskeletal disorders in
children.
How Are Growth Plate Injuries
Treated?
As indicated in the previous section, treatment depends on
the type of fracture. Treatment, which should be started as soon as
possible after injury, generally involves a mix of the following:
Immobilization
The affected limb is often put in a cast or splint, and
the child is told to limit any activity that puts pressure on the
injured area.
Manipulation or Surgery
If the fracture is displaced, the doctor will have to put
the bones or joints back in their correct positions, either by using his
or her hands (called manipulation) or by performing surgery (open
reduction and internal fixation). After the procedure, the bone will be
set in place so it can heal without moving. This is usually done with a
cast that encloses the injured growth plate and the joints on both sides
of it. The cast is left in place until the injury heals, which can take
anywhere from a few weeks to two or more months for serious injuries.
The need for manipulation or surgery depends on the location and extent
of the injury, its effect on nearby nerves and blood vessels, and the
child’s age.
Strengthening and Range-of-Motion Exercises
These treatments may also be recommended after the
fracture is healed.
Long-Term Followup
Long-term followup is usually necessary to monitor the
child’s recuperation and growth. Evaluation includes x rays of matching
limbs at 3- to 6-month intervals for at least 2 years. Some fractures
require periodic evaluations until the child’s bones have finished
growing. Sometimes a growth arrest line may appear as a marker of the
injury. Continued bone growth away from that line may mean that there
will not be a long-term problem, and the doctor may decide to stop
following the patient.
What Is the Prognosis for Growth in the
Involved Limb of a Child With a Growth Plate Injury?
About 85 percent of growth plate fractures heal without
any lasting effect. Whether an arrest of growth occurs depends on the
following factors, in descending order of importance:
- Severity of the injury--If the injury causes the blood
supply to the epiphysis to be cut off, growth can be stunted. If the
growth plate is shifted, shattered, or crushed, a bony bridge is more
likely to form and the risk of growth retardation is higher. An open
injury in which the skin is broken carries the risk of infection,
which could destroy the growth plate.
- Age of the child--In a younger child, the bones have a
great deal of growing to do; therefore, growth arrest can be more
serious, and closer surveillance is needed. It is also true, however,
that younger bones have a greater ability to remodel.
- Which growth plate is injured--Some growth plates, such as
those in the region of the knee, are more responsible for extensive
bone growth than others.
- Type of growth plate fracture--The five fracture types are
described in the section, How
Are Growth Plate Fractures Diagnosed?. Types IV and V are the most
serious.
Treatment depends on the above factors and also bears on
the prognosis.
The most frequent complication of a growth plate fracture
is premature arrest of bone growth. The affected bone grows less than it
would have without the injury, and the resulting limb could be shorter
than the opposite, uninjured limb. If only part of the growth plate is
injured, growth may be lopsided and the limb may become crooked.
Growth plate injuries at the knee are at greatest risk of
complications. Nerve and blood vessel damage occurs most frequently
there. Injuries to the knee have a much higher incidence of premature
growth arrest and crooked growth.
What Are Researchers Trying To Learn About
Growth Plate Injuries?
Researchers continue to develop methods to optimize the
diagnosis and treatment of growth plate injuries and to improve patient
outcomes. Examples of such work include:
- Removal of a growth-blocking "bridge" or bar of bone that can form
across a growth plate following a fracture. After the bridge is
removed, fat, cartilage, or other materials are inserted in its place
to prevent the bridge from forming again.
- The investigation of drugs that protect the growth plate during
radiation treatment.
- Development of methods to regenerate musculoskeletal tissue by
using principles of tissue engineering.
To improve the early diagnosis of growth plate injuries,
the National Institute of Arthritis and Musculosketetal and Skin
Diseases (NIAMS) is supporting a study to evaluate the use of MRI to
visualize young bones and enable prompt, appropriate treatment. In May
1997, the NIAMS, together with the National Institute of Child Health
and Human Development (NICHD), the American Academy of Orthopaedic
Surgeons (AAOS), and the Orthopaedic Research and Education Foundation,
supported a conference on skeletal growth and development. The resulting
publication, Skeletal Growth and Development: Clinical Issues and
Basic Science Advances, can be obtained from the AAOS at the address
listed near the end of this booklet. In March 2000, the NIAMS supported
the First International Conference on Growth Plate.
The NIAMS is working with the NICHD, the National
Institute of Dental and Craniofacial Research, and the National
Institute of Diabetes and Digestive and Kidney Diseases to support a
research initiative in the area of skeletal growth and development. The
purpose of the initiative is to:
- Stimulate research to identify and understand the action of the
genes that regulate skeletal development
- Evaluate factors that affect growth plate function
- Develop animal models to study disturbances in skeletal growth and
development
- Find new ways to correct musculoskeletal deformities.
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