Dwarfism and Skeletal Dysplasias

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What are dwarfism and skeletal dysplasias?

In skeletal dysplasias, like dwarfism, a child’s bones do not grow in the usual way. Often, children with skeletal dysplasias are much shorter than average, or their bones may be more fragile than is typical.

Dwarfism is a type of short stature that happens when a child’s bones cannot grow to a typical length. Instead, the bones are short and sometimes crooked. Your child’s arms, legs or trunk may be short compared with the rest of their body. The most common type of dwarfism is called achondroplasia (ay-con-druh-PLAY-zhuh).

How common are skeletal dysplasias?

There are more than 400 types of skeletal dysplasia. Together, these conditions affect 1 in 5,000 children. Achondroplasia affects 1 in 15,000 children.
What causes skeletal dysplasias?

Most of the time, skeletal dysplasia is caused by a problem with a involved in bone growth. Sometimes this gene is passed on from a parent to a child. Other times, a baby has a new random change in a gene, and they are the first in the family to have skeletal dysplasia. The gene change is not caused by something parents did or didn’t do before or during the pregnancy.
What are other reasons a child may have short stature?
Children can be shorter than others their age for many reasons. They may not have any form of skeletal dysplasia. They may have:
- Parents with short stature
- A problem with hormones that help control growth
- A disease that affects the kidneys, heart or intestines
- A problem with nutrition or digestion that stops calcium and vitamin D from working well in their bodies

Orthopedics and Sports Medicine at Seattle Children's

Seattle Children’s pediatric orthopedics team partners with researchers around the world to make sure we are using the latest treatment approaches and technologies.

What are the symptoms of dwarfism and skeletal dysplasias?

Children with dwarfism are very far below average height for their age. They may not have full motion in their joints. Sometimes, they have bowlegs or knock-knees. Often, their arms, legs or trunk are short compared with the rest of their body compared with other children of their age. They may have facial features that help doctors diagnose the condition. For example, their head may be larger or the middle of their face may be flatter than is typical.

How are dwarfism and skeletal dysplasias diagnosed?

Children usually come to us after their parents, caregiver or doctors notice things like these:

They are not growing as quickly as other children their age.
Their arms and legs, trunk or face look different from other children’s.
They get scoliosis before age 10.
They break their bones more easily than usual, such as in .

We will ask about your child’s growth and medical history and examine them. We may take and suggest other tests that can give us more details.

Growth and medical history
When you come to our clinic, we ask about:
- Your child’s growth history
- The height of members of your child’s family
- How the pregnancy went
- Any health conditions your child has
- If your child has met common
- If anyone else in your child’s family has symptoms or features like theirs
Physical exam and X-rays

Next, we examine your child. We measure their height, the length of their arms and legs and the distance around their head. We take X-rays of their arms, legs, pelvis, spine and skull. This is called a skeletal survey. It helps us find out which bones may not be growing the way they usually do.
Other tests your child may have
- Blood and urine tests. We may take blood and urine samples from your child to test for levels of hormones and other chemicals. This may help us understand how your child is growing.
- MRI or CT scan. Children may have other conditions that sometimes go along with skeletal dysplasias. So, we may ask your child to have an MRI (magnetic resonance imaging) scan or a CT (computed tomography) scan to check for signs of these conditions.
- Sleep study. Often, children with dysplasias have trouble breathing at night (obstructive sleep apnea or central sleep apnea). We may ask your child to have a sleep study. This is a test to check how well your child sleeps and what happens in their body during sleep, like their brain waves, heartbeat and how well they breathe.
Genetic counseling

Our staff includes experts called who can help explain genetic conditions and the chance of having a child with a skeletal dysplasia.

How are dwarfism and skeletal dysplasias treated?

Our goal is to help children, teens and adults with skeletal dysplasias do everything they want or need to do and thrive in life. This means we are ready to provide treatment and support for every aspect of the condition, from limb and spine problems to social and family concerns. Our Skeletal Health Program is here to help with a wide range of needs.

We manage all parts of your child’s care. This may include medicines to strengthen their bones, visits to check their growth and development and supportive or medical care to treat other health issues. We also offer surgery to make limbs straighter, for families who may want this option, and surgery to treat spinal curves.

Medicines for skeletal dysplasia

Medicines like these may help protect your child’s bones:

Pamidronate. This belongs to a group of medicines called bisphosphonates. They slow normal bone breakdown so bone mass can increase. We may use pamidronate in children with low bone mineral density and fractures. This includes children with osteogenesis imperfecta. Read more about pamidronate (PDF) (Spanish).
Zoledronic acid. This is another bisphosphonate, used to make bones stronger. Read more about zoledronic acid (PDF) (Spanish).
Vitamin D. Supplements of vitamin D may be important to building strong bones. This matters most if your child’s body has trouble absorbing or using enough vitamin D from their diet alone.
Calcium. Supplements of calcium may help strengthen bones in children with low calcium in their diet.
Burosumab-twza. This medicine may help strengthen bones in children with a condition called X-linked hypophosphatemia. They have weak bones because their bodies do not hold onto enough of the mineral phosphorus.

If you are interested in medicine that may help your child grow taller, we offer vosoritide. It may increase height in children with achondroplasia.

Limb-straightening surgery

In children with skeletal dysplasias, sometimes the arms and legs grow crooked. This can cause hip or knee pain. It can also make walking and running difficult. In some cases, surgery to realign the joints may be helpful.

The options include:

Putting metal plates and screws into the (tethering the growth plate) in 1 or more bones to change the way a limb is growing
Cutting a bone, straightening it and then fixing it in place with metal plates and screws

Scoliosis or kyphosis surgery

Children with dwarfism often have a sideways curve in the spine (scoliosis). They may also have a forward curve in the middle of the spine (kyphosis) that is larger than typical. If your child has severe scoliosis or kyphosis, you and your child’s doctor may talk about doing surgery. Surgeons can use metal rods and screws to help straighten the spine. Some children need .

Experts in our Spine Program treat all types of spine problems, including those linked with dwarfism and skeletal dysplasias.

Spinal stenosis surgery

Spinal stenosis often affects people with dwarfism. In stenosis, the is narrower than usual. This can put pressure on the . Pressure may cause pain and weakness in your child’s arms and legs. It may also cause breathing trouble.

In these cases, you and your child’s doctor may talk about surgery. Surgeons can open up the spinal canal to take pressure off the spinal cord and nerves.

Other care tailored to your child

Your child’s team in the Skeletal Health Program will involve as many specialists as your child needs. For example, skeletal dysplasia can affect the skull, ears, jaw and teeth as well as the limbs and spine. So, we often work closely with experts from Audiology and Dentistry. For children with sleep apnea, our Sleep Medicine team provides expert care.

Support for your child and family

We understand the social and physical challenges your child and family may face. We offer social, medical and psychological support services at Seattle Children’s. We also connect you with services in your community. We encourage families to connect with groups like Little People of America, Inc., the Osteogenesis Imperfecta Foundation and Camp Korey.

Why choose Seattle Children’s for dwarfism and skeletal dysplasia treatment?

Seattle Children’s Skeletal Health Program cares for babies, children, teens and some adults with dwarfism, other types of skeletal dysplasias and metabolic bone diseases. We see many children each year with these conditions.

The experts you need are here
- The Skeletal Health Program brings together , endocrinologists, geneticists, , , nurses and nurse practitioners to provide comprehensive care for your child.
- Medical centers that do not specialize in skeletal dysplasias rarely see these conditions. At Seattle Children’s, we see many children with skeletal dysplasia. Our team is highly skilled and very experienced in the treatments your child may need.
- Our doctors and nurses are known worldwide for their expertise in dwarfism and skeletal dysplasias. We have written widely on the subject.
Comprehensive care for your whole child
- We begin by taking care to make the correct diagnosis and understand all the ways your child’s condition affects them. Careful diagnosis helps us make sure your child gets the right treatment — and that they avoid treatment they do not need.
- Dwarfism and skeletal dysplasia can affect more than a child’s bones, muscles and joints. That’s why we connect you and your family with any expert your child may need across Seattle Children’s. For example, we often work with Neurosurgery, Sleep Medicine, Otolaryngology, Audiology, the Heart Center and Dentistry, as well as social services.
- Experts in our Spine Program treat spine problems linked with dwarfism and skeletal dysplasias. We have the largest pediatric spine center in the Pacific Northwest. Our spine team cares for even the most complex spinal problems in children of all ages.
We treat infants through adults
- For some families, our work begins even before their baby is born. If a prenatal (before birth) ultrasound suggests that your developing baby may have a skeletal dysplasia, we work with Seattle Children’s Fetal Care and Treatment Center. Together, our experts provide diagnostic and counseling services to you and your family.
- After birth, we tailor care to your child’s age and developmental stage. Our focus is always on your child’s long-term health and wellness. We help you learn what to expect during your child’s life, from birth to adulthood.
- For young adult patients who are ready to move to adult care, we can guide you in finding local experts.
Support for your whole family
- We know it can be stressful to have a child with a skeletal condition and to find the treatment they need. Everyone at Seattle Children’s works to make your experience here as easy as we can on your whole family.
- Your child’s team does more than plan and provide care for your child. We also make sure you and your child understand your child’s condition and treatment options.
- Seattle Children’s supports your family with a range of resources. Our Child Life specialists, Family Resource Center and Guest Services are here to help.
- For more support beyond our walls, the Skeletal Health Program has close relationships with:
  - Little People of America, Inc., the advocacy and support group for families with dwarfism
  - Osteogenesis Imperfecta Foundation
  - Camp Korey, which offers camps for children with skeletal dysplasia and metabolic bone diseases
Research and advances to improve care
- Our team has done research to expand medical knowledge about dwarfism and skeletal dysplasias and to improve care and quality of life for patients everywhere.
- Seattle Children’s doctors helped to found the Skeletal Dysplasia Management Consortium. This international panel of experts developed guidelines on how to diagnose and treat skeletal dysplasias.
- Our doctors were part of an international panel of experts that developed evidence-based guidelines to diagnose and treat in babies with achondroplasia.
- Our team did research on the medicine pamidronate (which slows bone breakdown) for children with severe . It showed they were better able to take part in sports and other physical activities after using this medicine for a year.
- We are involved in studies to check the results of 2 medicines that may help children with genetic conditions that affect bone health. They are vosoritide to increase height in children with achondroplasia and burosumab-twza to strengthen bones in children with X-linked hypophosphatemia (low levels of phosphorus in the blood).
- Learn more about current orthopedics research at Seattle Children’s.