The lower leg has two bones: the tibia and fibula. The tibia is the larger bone. It supports most of your body weight and is an important part of both the knee joint and the ankle joint.

Tibial hemimelia means that part or all of the tibia, the larger bone in the lower leg, is missing. 

Tibial hemimelia is a congenital condition, which means it is present at birth.

• In the mildest cases, the tibia may be only a little shorter than normal.
• In the most severe cases, the tibia may be completely missing.

Tibial hemimelia usually affects only one leg. But in about one-third of cases, both legs are affected. When only one leg is affected, it is usually the right leg, although doctors do not know why.

A baby boy with tibial hemimelia affecting both legs.

Reproduced from Krajbich IJ: Lower limb deficiencies and amputations.  J Am Acad Orthop Surgeons 1998; 6:358-367.

Types of Tibial Hemimelia

Doctors usually divide tibial hemimelia into four types. The types are based on how much of the tibia is missing. Knowing the type helps your child's doctor choose the best treatment plan for your child.

• Type I. In this type, the tibia is completely missing. Because of this, the child's knee and ankle joints usually do not work.
• Type II. In this type, the lower half of the tibia is missing. The knee joint usually works somewhat normally, but the ankle joint does not work.
• Type III. In this type, the upper half of the tibia is missing. The knee joint usually does not work, but the ankle joint may work somewhat normally. This type of tibial hemimelia is extremely rare.
• Type IV.  In this type, the child has a short tibia, and the lower ends of the tibia and fibula near the ankle joint are separated from each other. This makes the ankle joint very abnormal.

Other Medical Problems

Many children with tibial hemimelia are also born with other problems in their feet and legs, such as:

• A short femur (thighbone)
• A bifid femur (the lower end of the thighbone is split into two parts)
• An absent extensor mechanism (the muscles, ligaments, and other parts that help the knee straighten are missing)
• Clubfoot (the foot turns inward)
• Missing or extra toes

Some children with tibial hemimelia may also have conditions that affect their arms.

X-ray shows a healthy 7-month-old boy with tibial hemimelia of both legs. On the right side, the bottom end of his femur is split into two (bifid femur) and his tibia is missing. On the left side, his femur appears relatively normal, but the bottom half of his tibia is missing.

Most of the time, doctors do not know exactly why a baby is born with tibial hemimelia. Sometimes, however, the condition can be passed down in a family.

Sometimes tibial hemimelia is linked to a medical condition or syndrome that affects several parts of the body, such as:

• Werner's syndrome
• Langer-Giedion syndrome
• CHARGE syndrome (coloboma, heart defects, atresia chonae, growth retardation, genital abnormalities, ear deformities)

Severe cases of tibial hemimelia are usually found before birth during a prenatal ultrasound. Milder cases may not be noticed until after birth, when parents see a difference in leg length as their child grows.

Medical History and Physical Examination

Tibial hemimelia can sometimes be inherited. Your child's doctor will ask if your family has any known medical syndromes.

During the exam, your child's doctor will measure the length and width of your child's arms and legs. The doctor will move your child's legs and feet in different ways to learn more about the knee and ankle joints. The exam will not be painful.

Tests

Tests help your child's doctor confirm the diagnosis and plan treatment.

X-rays. X-rays provide images of bone. The doctor may order X-rays from your child's hips down to their feet to see which bones are present and which are missing. X-rays also help the doctor estimate the difference in the length of your child's legs.

X-rays can be done as soon as your child is born. Even though not all of the bone can be seen during infancy, doctors can still learn a lot about the shortened tibia from this first set of X-rays.

Magnetic resonance imaging (MRI) scans. Your child's doctor may order an MRI to learn more about your child’s knee and ankle joints. The condition of these joints is very important when making treatment recommendations.

Genetic testing. The doctor may recommend an evaluation by a genetic specialist.

The goals of treatment are for the child's leg to work as well as possible, to be pain free, and be as close as possible in length to the other leg by the time the child is fully grown.

Treatment for tibial hemimelia involves a team of medical specialists. The team may include an orthopaedic surgeon, a pediatrician, therapists, and a brace maker.

Your child's treatment plan will depend on many things, including:

• How much of the tibia is missing
• How well the knee and ankle joints work
• The difference in leg length
• Your child's overall health
• Your family's preference for a certain procedure

Nonsurgical Treatment

Almost all children with tibial hemimelia will eventually need surgery to help them function better. In very mild cases, however, nonsurgical treatment may sometimes be used until surgery is needed.

Nonsurgical treatment may include:

• Wearing a shoe lift. If the child's foot fits in a shoe, a shoe lift can help even out a small difference in leg length. 
• Prosthetics. For a larger difference in leg length, an artificial device can be fitted over the shorter limb so the child's foot can rest flat on the floor. These "accommodative" prostheses become harder to make over time. Then, some kind of surgery is almost always needed to help the child walk and stand better.

Surgical Treatment

The surgeries most often used to treat tibial hemimelia are:

• Limb reconstruction and lengthening
• Limb amputation

Limb reconstruction and lengthening. For children with less severe tibial hemimelia, limb reconstruction and lengthening may be a good treatment choice.

Reconstruction usually includes one or more surgeries to repair the bones, muscles, and joints affected by the hemimelia. After that, the leg is slowly lengthened by using an external fixator. 

The external fixator is worn until the lengthened bone is strong enough to safely support the patient.

Limb lengthening usually requires several operations over a number of years.

Limb amputation. For many children with tibial hemimelia, limb reconstruction and lengthening may not give the best results — for example, if the child does not have a working ankle joint or cannot actively straighten their knee. If the parts that help the knee straighten are missing, reconstruction and lengthening are more difficult.

In these cases, the best chance for the child to have an active life often involves amputation of the affected limb. After the limb is amputated, a prosthetist (brace maker) will fit the child with a prosthetic limb. As the child grows, the prosthetist will adjust the prosthesis or make a new one.

Choosing whether to have an amputation is, understandably, very hard for parents. Your child's surgeon and the other medical specialists on your child's care team will give you and your family support and information. This will help you decide which treatment is best for your child.

Living with tibial hemimelia and getting treatment for it can be hard for a child and their family. Meeting other children with limb differences and their families can remind you that you are not alone. It can also be very helpful source of information and support.

You can find online support and discussion groups for families of children with limb deficiencies.

Your child's doctor or a hospital social worker may be able to put you in touch with families like yours so that you can meet and talk with them about their experiences.

Thanks to advances in prosthetics and limb reconstruction, most children with tibial hemimelia are eventually able to participate in almost any activity. It is important to help your child by being supportive and encouraging a positive self-image. If your child is struggling with either the emotional or physical aspects of treatment, be sure to share your concerns with your child's doctor.

For more information about treatment for conditions like tibial hemimelia, please visit the Limb Lengthening and Reconstruction Society.