External fixation is a limb lengthening technique where an apparatus is mounted to the outside of the body. The two types of external fixators that are used in limb lengthening are:
- Monolateral fixator: This fixator is mounted to one side of the limb (typically the femur and humerus)
- Circular fixator: This fixator or "frame" is mounted around the limb
Monolateral fixators are usually placed on the outer thigh or arm, or the inner leg. Sometimes they are used to treat broken bones, especially if the bone or the skin is badly damaged.
Circular fixators are mounted completely around the limb. The frame is made of at least two carbon fiber or aluminum rings connected by six struts.
For any type of external fixator, either monolateral or circular, the "frame" is mounted to the body by placing special pins or wires through the skin and into the bone. There is a special coating (hydroxyapatite) on the pins to allow them to stick to the bone. This coating decreases, but does not eliminate, the risk of pin infections. Pin infections are common, but preventable. It’s extremely important that the pins are cleaned once or twice a day.
Your child will likely require:
- Weekly doctor visits
- Multiple adjustments to the frame (on a daily basis)
- Physical therapy sessions
- Crutches to help with daily activities
Dressing around the external fixator can sometimes be challenging (particularly if it is on the femur), but your doctor can help guide you and your child through the process.
Before the external fixator is removed, your doctor will likely want your child to be walking without any limitations. The fixator is removed in the operating room under general anesthesia. Once it is removed, your doctor may place your child’s leg in a walking cast for a short period of time or require crutches for three to four weeks, until the bone is stronger.