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Skeletal Dysplasia / Dwarfism

Skeletal dysplasia is not just one disorder—it’s a group of more than 300 disorders. It occurs when a child’s bones don’t develop the way they’re supposed to, usually causing short stature.

One type of short stature is called dwarfism. It’s a condition where a child’s bones can’t grow to an average length. This results in the bones being short and sometimes crooked. A person is considered a dwarf when his adult height is 4 feet 10 inches or less.   

Types

Dwarfism can be classified in two ways:

DISPROPORTIONATE DWARFISM

A person with disproportionate dwarfism has body parts that are not proportionate to each other—they can be several different sizes.

In most cases, the trunk is average-sized and the limbs are short. However, it’s also possible that a person could have a very short trunk, and limbs that are technically “short” but appear large compared to the trunk. Either way, the head usually seems disproportionately large when compared to the rest of the body.

Some of the most common types and symptoms of disproportionate dwarfism include:

Achondroplasia

  • Is the most common type of dwarfism, causing about 70% of cases.
  • Occurs when cartilage—the tissue that makes up most of a fetus’s skeleton during development—doesn’t convert to bone the way normal cartilage does.
  • Usually involves average-sized trunk with small arms and legs.
  • May cause a child to have weak muscles, dental problems, flat feet, or bowed (curved) legs.

 

Spondyloepiphyseal dysplasia congenita (SEDc)

  • Affects the bones in the spine, legs, and arms.
  • May cause problems with vision and hearing.
  • Involves scoliosis (curve in the spine) that worsens over time.
  • Involves possible changes in facial features, like cleft palate (opening at the roof of the mouth).
  • Comes with a likelihood of developing arthritis early in life.
  • Involves possible deformities in the feet, legs, back, or chest.

 

Diastrophic dysplasia

  • Involves very short arms and legs.
  • Comes with a likelihood of early-onset osteoarthritis and joint pain.
  • Involves cleft palate in about 50% of newborns with this condition.
  • Presents possible swelling of the outside of the ears, leading to thickened, deformed ears.

 

Pseudoachondroplasia

  • Often causes joint pain.
  • Probably will not appear at birth— the child’s growth rate will slow down by age two.
  • Involves joint laxity (looseness), early-onset arthritis, and joint pain.
  • May involve scoliosis.

 

Hypochondroplasia

  • Causes disproportionately small hands, feet, arms, and legs.
  • Involves bowed legs that improve over time.
  • Can cause a prominent forehead.
  • Is not always obvious. The child’s short stature may not be recognized until early to mid-childhood years—and sometimes, not until adulthood.
  • Involves mild intellectual disability in about 10% of cases.

 

Osteogenesis imperfecta (OI)

  • Involves bones that do not form well and become brittle. They can break easily from a mild trauma or for no reason at all.
  • May appear in a fetus before birth in the form of fractures (broken bones).
  • Could cause problems with hearing, breathing, or tooth development.

 

Turner syndrome

  • Affects development in females.
  • Usually involves normal growth until about age five.
  • Causes the ovaries to stop functioning correctly when the girl is still young, usually causing infertility.
  • Prevents puberty in most girls, unless they receive hormone therapy.
  • Can cause extra folds of skin on the neck, puffy and swollen hands or feet, kidney problems, or heart defects.
  • Involves a small risk of learning disabilities, developmental delays, or behavioral problems.

 

PROPORTIONATE DWARFISM

Less frequently, a person may have a head, limbs, and trunk that are short but still proportionate to one another. This type of dwarfism can affect other parts of the body, like the heart.

 

Causes

Most cases of skeletal dysplasia and disproportionate dwarfism are caused by a defective gene—one that stops bones from growing normally. Although dwarfism can be passed on from parent to child, it’s usually due to a random mutation (change) in a gene.

Proportionate dwarfism is often caused by another medical condition that limits growth and development. One of the most common causes is growth hormone deficiency—a condition where a child’s pituitary gland doesn’t produce enough growth hormone to help her body grow.

Diagnosis

Physical appearance is often enough to alert a physician to the child’s dwarfism. Once he suspects dwarfism, he may run a number of tests:

  • Imaging tests: Tests like X-rays and magnetic resonance imaging (MRI) can help the physician see abnormalities of the head and body in more detail. They can also show problems with the hypothalamus or pituitary gland—body parts associated with growth hormone.
  • Hormone tests: These tests check levels of hormones that are needed for proper development, like growth hormone.
  • Family history: Since dwarfism often runs in families, getting a family history can help the physician determine whether the child’s short stature is the average size for her family.

 

Even if the physician can’t see signs of dwarfism, he may still be able to make a diagnosis. All children get height, weight, and head circumference measurements at well-child visits. The physician can use these measurements to look for signs of dwarfism, like abnormal growth patterns or a large head.

 

Treatment

Treatment for disproportionate dwarfism usually doesn’t make a child taller. However, there are treatments for complications caused by dwarfism. These may include:

  • Surgery: A surgeon may be able to take steps such as correcting a spine that isn’t forming in the normal shape, or bones that aren’t growing in the right direction.
  • Growth hormone therapy: A child with dwarfism caused by abnormal hormone levels may receive injections of growth hormone. This can only correct short stature in a child with proportionate dwarfism.
  • Estrogen therapy: This treatment may be given to a female child with Turner syndrome. Estrogen will initiate puberty, and can stimulate growth of her sex organs. This therapy can also help her pay attention, plan tasks, and have a better sense visual or spatial relationships.

Prevention

Currently, there is no known way to prevent dwarfism.

 

The OIC Skeletal Dysplasia Team

OIC has a broad range of specialists who can help your child with his or her skeletal dysplasia. Based on your child’s condition your team could include:

The Pediatric Orthopaedist specializes in the musculoskeletal system of children. They provide surgical interventions when necessary such as tendon lengthening.

The Pediatrician reviews medical issues and coordinates the general healthcare of the patient, in addition to working with the orthopaedic surgeon for pre-operative assessments if surgery is indicated and overseeing medical issues for hospitalized patients.

The Nurse Coordinator assists in making sure all medical orders are carried out, and provides case management and nursing assessment for the patient. 

You may also work with physical therapists who will help plan, develop, implement and monitor a physical therapy plan to help reduce pain, or improve or increase mobility.