What to Know About Fibular Hemimelia

Medically Reviewed by Poonam Sachdev on May 03, 2022

People with fibular hemimelia are born with certain leg deformities or abnormalities. If your child has fibula hemimelia, they might have trouble walking or standing and will need medical treatments to help them use their legs effectively. 

Keep reading to learn more about fibular hemimelia and how it’s diagnosed and treated, as well as common outcomes for people with this condition. 

What Is Fibular Hemimelia?

Around the seventh week of pregnancy, your baby will develop their lower limb buds, which are small, paddle-like protrusions that will eventually form their legs and feet.

Fibular hemimelia is a type of post-axial hypoplasia of the lower extremities that happens when one of the baby’s limb buds didn’t develop as it should. Babies with fibular hemimelia will be missing part or all of their fibula bone in their lower leg.

Some children have fibular hemimelia in both legs, but often, only one is affected, making it shorter than the other. They might also have other leg or foot deformities like a bowed or bent leg and missing toes.

What Are Fibular Hemimelia Symptoms?

Fibular hemimelia affects each person differently, and symptoms can range from mild to severe. Some symptoms include: 

  • Missing or partially developed fibula
  • Having one leg shorter than the other
  • Ankles or feet that are abnormally formed
  • Knees that bend inward instead of outward
  • Missing or weak knee ligaments
  • Bowed lower legs
  • Missing or malformed toes
  • Shallow hip joints

What Are Fibular Hemimelia Causes?

Fibular hemimelia is congenital, which means that people with the condition are born with it. Developmental problems that cause fibular hemimelia will happen between the 6th and 8th week of pregnancy, when your baby’s limb buds are forming.

Fibular hemimelia happens randomly, and the exact cause is unknown. One theory is that the genes responsible for forming a baby’s leg during pregnancy are activated in the wrong order, causing deformities.

Is Fibular Hemimelia Genetic?

Currently, there's no evidence that fibular hemimelia is an inherited or genetic trait that is passed down. Most children born with fibular hemimelia don't have any family history of birth defects.

The risk of having a baby with fibular hemimelia is about 1 in 40,000. People who have one child with fibular hemimelia are not at any greater risk of having another child with the same condition. Likewise, a person with fibular hemimelia has the same chances of having a child with the condition as someone who does not have it.

How Is Fibular Hemimelia Diagnosed?

Doctors can often diagnose fibular hemimelia before your child is born during prenatal ultrasounds to check your baby’s development. After your baby is born, fibular hemimelia is diagnosed during their newborn examination. Your doctor might want your baby to have imaging tests such as an x-ray or MRI to see how much of their bones, joints, and ligaments are affected.

What Are Fibular Hemimelia Treatment Options?

Treatment for fibular hemimelia depends on how much the condition affects your child. Doctors will work with you to create a care plan that best suits your child’s unique needs.

Children with very mild forms of fibular hemimelia might be given a special shoe insert to help them make up the difference in leg length, or they might not need treatment at all.

If your child has a more moderate or severe form of fibular hemimelia, your doctor might recommend surgery to help them stand, walk, and use their leg as normally as possible. Different types of surgeries can correct the issues fibular hemimelia causes.

Leg-lengthening surgery. Children who have surgery to lengthen their shorter legs will often need multiple surgeries over many years, depending on their needs and goals. Surgery is usually done over the course of 4 to 6 years, with severe cases needing about 3 surgeries in total. The surgery works by attaching a lengthening device to the bone on your child’s shorter leg. Over time, leg-lengthening surgery can help your child’s shorter leg grow an average of 8 inches.

Epiphysiodesis. If your child only has a small difference between the length of their legs and is currently still growing, your doctor might suggest surgery called epiphysiodesis. Rather than trying to lengthen their shorter leg, your doctor will either scrape or compress growth plates in your child’s unaffected leg. Keeping their longer leg from growing can help give their shorter leg time to grow and become more even.

Hip, knee, and ankle surgeries. Fibular hemimelia often affects the joints along with the bones. Surgeries to reconstruct or correct joint issues can help them stand and walk more effectively. Hip and knee surgeries are often done first when your child is around 18 to 24 months old. Ankle surgery can be done 6 to 12 months later or on its own if your child’s hip and knee aren’t affected.

Other corrective surgeries. As your child grows, they might need additional surgeries to straighten crooked bones or correct foot, muscle, and ligament problems.

Amputation. If your child has a very severe form of fibular hemimelia where one leg is significantly shorter than the other, or their deformities are too severe to be corrected with other forms of surgery, your doctor might recommend amputation. Removing part of your child’s foot or leg will allow them to be better fitted with a prosthesis. Prosthetic legs can help your child stand, walk, jump, run and play like other children.

Along with surgery, proper physical therapy plays a vital role in treating and managing fibular hemimelia. Your child will need to attend regular physical therapy sessions and perform home exercises to help them reach their full potential.

What Are Fibular Hemimelia Outcomes?

If your child is born with fibular hemimelia, they will need medical treatment as long as they are still growing. 

While reaching their full potential takes time, children with fibular hemimelia will adapt well. On average, your child will walk by the time they’re 12 to 16 months old, even if they have severely affected bones, ankles, and feet. Most go on to be very active and play sports like other children.

Show Sources


International Center for Limb Lengthening: “What is fibular hemimelia?”

KidsHealth: “Fibular Hemimelia.”

Mayo Clinic: “Fetal development: The 1st trimester.”

Paley Orthopedic and Spine Institute: “Fibular Hemimelia.”

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