Dwarfism and Skeletal Dysplasias

Skeletal dysplasias affect 1 in 5,000 children. Achondroplasia is less common and affects 1 in 15,000 children.

Most skeletal dysplasia is caused by a defective gene that stops bone from growing in the usual way. Sometimes this gene is passed on from a parent to a child (genetic). Much more often, though, the condition arises from a new random change in a gene (spontaneous genetic mutation), and the baby is the first in the family to be affected.

Children can be shorter than others their age for many reasons but not have any form of skeletal dysplasia. They may have:

• Short parents
• A lack of the 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 properly in their bodies and promoting growth

The Skeletal Health Program brings together orthopedic doctors, endocrinologists, pulmonologists, geneticists, radiologists, nurses and nurse practitioners to care for your child.

Our doctors and nurses have a great deal of experience and are known internationally for their expertise in dwarfism and skeletal dysplasias. We have also written widely on the subject and are active with Little People of America, Inc., the advocacy and support group for families with dwarfism, and Camp Korey, which offers camps for children with skeletal dysplasia and metabolic bone diseases.

Based on your child’s needs, the Skeletal Health Program team will involve specialists from other areas of Seattle Children’s, like Neurosurgery, Pulmonary and 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.

For some families, our work begins even before their baby is born. If a pregnant woman’s ultrasound suggests that her developing baby may have a skeletal dysplasia, we work with Seattle Children’s Fetal Care and Treatment Center to provide diagnostic and counseling services to her and her family.

After birth, we tailor care to your child’s age and developmental stage, always with a focus on their long-term health and wellness.

The Skeletal Health Program also provides evaluation, genetic counseling, prenatal consultation and medical management for adults with dwarfism and rare bone conditions. If adult patients need surgery, we work with surgeons from UW Medicine.

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. Recently Seattle Children’s doctors helped to found the Skeletal Dysplasia Management Consortium, an international panel of experts that developed evidence-based guidelines for diagnosing and treating skeletal dysplasias. Learn more about current orthopedics research at Seattle Children’s.

When you come to our clinic, we ask about your child’s growth history. We also ask about the height of members of your child’s family and how the mother’s pregnancy went.

We will want to know about any medical conditions your child has and any similar problems in the rest of your family.

Next, we examine your child. We measure their height and the length of their arms and legs. 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 in children.

• Blood tests. We may take blood samples from your child to test for levels of hormones and other chemicals that can help us understand how your child is growing.
• MRI or CT scan. Because children may have other conditions that come along with skeletal dysplasias, we may ask your child to have an MRI (magnetic resonance imaging) scan or a CT (computed tomography) scan to check for other problems.
• Sleep study. Often children with dysplasias have trouble breathing at night (obstructive sleep apnea or central sleep apnea), so we may ask them to have a sleep study.

Sometimes, pregnant women have an ultrasound that raises concerns about the growth of the baby in their womb. In these cases, we take specific ultrasound images that can help identify skeletal dysplasias before birth.

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

In children with skeletal dysplasias, sometimes the arms and legs grow crooked. This can cause hip or knee pain and 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 growth plate (tethering the growth plate) in one or more of your child’s bones to correct the way a limb is growing
• Cutting a bone, straightening it and then fixing it in place using metal plates and screws

Sometimes arms and legs are so short that it is difficult for a child to manage daily activities like cleaning themselves. In these cases, you and your child’s doctor may consider limb lengthening.

In this surgery, the doctor cuts the child’s bone and attaches one of these devices to the bone on both sides of the cut:

• A frame called a distractor, which is outside the body and goes through the skin into the bone
• A rod that is placed into the bone and can be adjusted with magnets

Over time, doctors adjust the device to gradually pull the pieces of bone away from each other. New bone forms in between, making the healed bone longer.

In children with dwarfism, common problems include a sideways curve in the spine (scoliosis) and a forward curve in the middle of the spine (kyphosis) that is larger than normal. If your child has severe scoliosis or kyphosis, you and your child’s doctor may consider surgery that uses metal rods and screws to help straighten the spine. Some children need growing rods.

Experts in our Spine Program treat spine problems linked with dwarfism and skeletal dysplasias.

Spinal stenosis is another condition that often affects people with dwarfism. The canal that the spinal cord runs through is narrower than usual, which can put pressure on the spinal cord. This causes 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 consider surgery to open up the spinal canal to take pressure off the spinal cord and nerves.

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

• Pamidronate. This belongs to a group of medicines called bisphosphonates. These medicines allow bone mass to increase by slowing normal bone breakdown. Pamidronate is used in children with low bone mineral density and fractures, including children with osteogenesis imperfecta. Read more about pamidronate (PDF).
• Enzyme replacement therapy. Some types of skeletal dysplasia occur when the body is missing an enzyme or the enzyme does not work the way it should. Medicine to provide enough working enzyme may reduce the effects of the disease.
• Vitamin D. Supplements of vitamin D may be important to building strong bones, especially if your child’s body has trouble absorbing or using enough vitamin D from their diet alone.

Your child’s team in the Skeletal Health Program will involve as many specialists your child needs, based on how your child is affected. We often work closely with experts from Audiology and Dentistry, for example, because skeletal dysplasia can affect the skull, ears, jaw and teeth as well as the limbs and spine.

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