Hemifacial Microsomia: Treatment

The Jaws
There are two basic approaches to centering and balancing the face. Currently, the most commonly recommended technique is to use distraction. I typically do not recommend the distraction technique at my center for a number of reasons which are listed below. The distraction technique involves making an osteotomy (cut in the bone) across the mandible (lower jaw) and attaching a metallic screw driven device to either side of this osteotomy. Pins are usually put through the skin into the bone, and the expansion device is attached to these pins. By turning a screw on the expansion device, a little each day, the bone slowly gets longer. There are also devices that are completely buried under the skin, except for a small metal bar, which pokes outside so that the screw can be turned. These distraction devices have been proven to successfully lengthen bone, and many doctors treating hemifacial microsomia recommend them. However, these devices are never used at the Craniofacial Center in Dallas for treating children affected on just one side, and only vary rarely for bilateral cases. There is a long list of reasons why I chose not to use these distraction devices:

  1. The overall complication rate for using these devices is about 1 out of 3 cases, as published in a survey of doctors. The complication rate was over 50% for doctors who had done fewer than 10 patients! Surveys typically underestimate complication rates, so that the actual complication rate may even be higher.
  2. These devices leave scars on the child's face that cannot be removed, and remain for a lifetime. Many doctors say that the scars will fade away and not be noticeable. I recommend seeing another child's scars first (in person, scars tend to not show up in photographs) before allowing this procedure to be done. There is an internal distraction device that does not leave facial scars, but this device has an even higher complication rate than the external device.
  3. The lower jaw may be lengthened in one direction with distraction, but distraction cannot widen the face. So, after distraction is done, the chin will line up nicely in the center of the face, but the side of the face will be even flatter. I believe that the use of distraction causes more children to require adding additional soft tissue to the face to help balance it. Rebuilding the facial skeleton (described below) reduces the need for additional operations to build up the soft tissues of the face.
  4. The teeth usually fit together fairly normally before using a distracter. However, after distraction, with one side of the lower jaw longer, the teeth will not line up with the other teeth. The result is that extensive orthodontia will be required, and eventually surgery may be needed to correct this problem.
  5. In order to attach the distracter to the jaw, it is necessary to use metal pins or screws. It is very likely that the front pins or screws will go through the child's un-erupted permanent teeth. The result is that the permanent tooth will not come up and the child will need an artificial tooth (or multiple artificial teeth).
  6. The upper jaw is not treated by distraction. This means that after the two operations are finished, one to put on the distracter and one to take it off, the upper jaw is still too small on the affected side, and will frequently need surgery to correct it.

The alternative to the use of distraction is a single-staged orthognathic procedure. From inside the mouth (so there are no scars on the face except for a short scar just in front of the ear) the upper and lower jaws may be cut and moved into a better position and, if necessary, an absent TMJ can be rebuilt using the child's own rib. It is best to delay this surgery until the child is older and wants to have the surgery done. This operation is longer and more complicated than putting on a distracter, and not every doctor is able to do this procedure; but the final result is that both jaws are aligned in the middle of the face in just one operation.

This single-staged operation is not a "perfect" operation. There is a possibility for an infection afterwards (about 10% chance) that may require a small operation to treat. If this operation is done at a very young age, there is a good chance that it may need to be repeated when the face is finished growing sometime around 16 to 18-years old. Overall, weighing all the positives and negatives, the single-staged correction is the best treatment, at the lowest risk.