Klane White, MD, is the chair of pediatric orthopedics and The Rose Brown Endowed Chair of Pediatric Orthopedic Surgery at Children’s Hospital Colorado in Aurora. He is also vice chair of the Department of Orthopedics at the University of Colorado School of Medicine.
Achondroplasia is a genetic bone growth condition. It affects about 1 in 20,000 live births. Because of a mutation (change) in the fibroblast growth factor receptor 3 (FGFR3) gene, it causes short stature (most people with the condition are about 4 feet), shortened arms and legs, and a larger-than-average head.
Kids with achondroplasia may have some delays in their gross motor development, like walking. That’s usually because their limbs are looser than typical children their age and their bodies have to support a larger head. But they may catch up by the time they are 2 or 3.
Most people with achondroplasia live long, full lives. But it’s important that they get the best medical care that they can to reduce risk of certain complications. We spoke to Klane White, MD, a pediatric orthopedic surgeon at Children’s Hospital Colorado in Aurora — who’s worked with kids and teens with achondroplasia for over 20 years — to get more insights into managing this condition.
Who gets achondroplasia?
Achondroplasia is a genetic condition. It’s caused by a mutation in the fibroblast growth factor receptor 3 (FGFR3) gene. This prevents bone growth, mainly in the arms and legs.
What are the early symptoms of achondroplasia? How is it diagnosed?
Signs of achondroplasia can be spotted sometimes even as early as a prenatal ultrasound. A doctor may suspect it if they see shorter long bones and a large head. Otherwise, it’s usually picked up at birth or shortly thereafter because while the baby has an average size trunk, they have unusually short arms and legs. It can then be confirmed with an X-ray.
We’ve seen babies in our clinic as young as 20 days. Definitely the earlier it’s picked up, the better it is for both the baby and their parents. We can provide information to the family about achondroplasia and start screening the baby for potential health problems.
What are some of the medical problems doctors look for in infants with achondroplasia?
When we see babies with achondroplasia, we like to keep a close eye on them. We ideally want to screen them every three months for the following potential complications:
A small foramen magnum. The foramen magnum is the opening through which your baby’s spinal cord leaves the head to travel down the spinal column. The foramen magnum in some babies is too small for their spinal cord, which can cause weakness, delays in gross motor skills, and central sleep apnea. We work closely with our pediatric neurosurgery colleagues in case one of our patients needs neurosurgery.
Sleep apnea. Babies with achondroplasia are more at risk to develop obstructive sleep apnea, the most common type of sleep apnea. It’s due to a couple of factors, like weak larynx muscles and smaller airways. If they do have sleep apnea, we refer to an ENT to remove their tonsils and adenoids.
Hydrocephalus. While most babies with achondroplasia have a larger head, we’re not concerned unless there’s a big jump in head circumference. In those cases, we have someone from our pediatric neurosurgical team take a look to make sure they haven’t developed hydrocephalus, or increased pressure from fluid in the skull. It’s treated with a shunt to drain out excess fluid from the brain.
What are some of the musculoskeletal issues you watch for in kids with achondroplasia?
As an orthopedic surgeon, I rarely do surgery on a child with achondroplasia before they turn 5. But after that, here are some things we watch carefully because they may require medical intervention:
Bow legs. Most toddlers and preschoolers with achondroplasia have some leg bowing, thanks to loose joints. But if it continues after the age of 5 or 6, it can affect their ability to walk and be active. In these cases, we do guided growth surgery. We use metal plates about the size of a paper clip to lock one side of the growth plate while allowing the other side to grow freely. Over time, this evens out the angle of your child’s knees and draws them back together.
Kyphosis. Some kids with achondroplasia may have a noticeable rounding of their back due to a curvature of their upper spine. It often resolves as they gain the ability to walk. But occasionally, they need surgery. We remove the bent parts of their spine and correct it with permanent screws and rods.
Spinal stenosis. This condition, where the spinal canal narrows and compresses the spinal cord and nerves, can occur in people with achondroplasia at any age. It requires a laminectomy, where part of the bony arch of the spine is removed to relieve pressure on the spinal cord and nerves.
What are some of the most exciting medical advances now in achondroplasia?
I’d say the possibilities with medical management. Historically, there have been very few treatment options for people with achondroplasia. But in 2021, the FDA approved vosoritide (Voxzogo) for use in kids of all ages. It binds to a certain receptor in the body, which reduces the activity of FGFR3. This stimulates bone growth. It appears to improve bone growth by a centimeter or two every year compared to placebo. It also seems to reduce some of the potential musculoskeletal complications like bow legging. There are a couple of other drugs in the pipeline, too.
What are your thoughts about limb lengthening?
Limb lengthening, or surgery to increase the length of arm or leg bones, is controversial. It’s not done routinely in the United States. I personally don’t perform them. These are intense surgeries. My perspective is that it’s not worth the loss of two years of a child’s life to go through limb lengthening so that they can be 10 inches taller. It can also cause complications, like joint stiffness, which limit function. But I do know quite a few adults with achondroplasia who did do limb lengthening between the ages of 10 and 12 and are very happy with that decision.
What advice would you give to the parents of a newborn with achondroplasia?
It’s normal for a parent to have some concerns and worries when their baby is born with achondroplasia. They will grow differently from other kids their own age, and there are some increased health risks, particularly around infancy. But as someone who has taken care of many kids with the condition, I can testify firsthand that virtually all of them grow up to become adults who live happy, productive lives. Yes, they are shorter, but many people with achondroplasia take pride in their short stature.
I still keep in touch with some of my patients who are now adults. They are working, and in relationships, and out just living their lives. None have kids yet, but I expect some will start soon! I’m proud of them all, and grateful that we are still in contact. The future is bright for babies born today with achondroplasia.