Fibular hemimelia—also known as fibula deficiency or longitudinal deficiency of the fibula—is a congenital (present at birth) condition in which part or all of the fibula (calf bone) is missing. The fibula is the smaller, outer bone of the lower leg. In this condition, the leg is also thinner and shorter. Most of the time, fibular hemimelia affects only one leg, but it may affect both sides. There are several other physical defects that may be associated with fibular hemimelia.

Children with prosthetic legs playing together

Signs and symptoms of fibular hemimelia may include:

  • Partial or complete absence of the anterior cruciate ligament (ACL) in the knee
  • Congenital femoral deficiency (CFD or PFFD)
  • Tarsal coalition, which means the talus and calcaneus bones are "stuck together" in an abnormal position
  • Complete or partial absence of some of the outer toes
  • Dimpling of skin and crookedness of the tibia bone

Symptoms of this condition are typically noticeable at birth, as the lower portion of one leg is visibly smaller and thinner compared to the other leg. The foot may also rest in an abnormal position—often pointing down and out—and some of the toes may be missing. We may use X-rays to confirm the diagnosis.

The ultimate goal of treatment, as with other congenital limb deficiencies, is to have a leg that functions well and is nearly equal in length to the opposite limb by the time your child is fully grown. Many children with fibular hemimelia are candidates for limb lengthening surgery.  There may be some cases were the child’s limb is too short, muscles are not present, or the ankle and foot are too involved requiring an amputation. Your child’s doctor will help guide you on which treatment method is best for your child.


This is a surgery to remove a limb. The loss of a limb can be scary, but our pediatric-trained specialists can help children who face this option realize an amputation will only briefly slow them down. Advancements in prosthetic technology have improved patient function and autonomy after surgery. There are also a wide range of adaptive sports and activities available to these patients. To help families make what can be a difficult decision, we connect them with patients and families who have been through the same procedures and recoveries.

Limb Lengthening Surgery

This is a procedure to lengthen or straighten a limb. Prior to the first lengthening surgery, the foot is usually corrected so it sits in line with the rest of the leg. Lengthening is done with either an external fixator or internal lengthening device. Internal lengthening devices cannot be used until your child is a teenager. This is due to size limitations of the nail and the fact that one of the growth plates of the leg is affected by the way the nail is inserted.