Purpose: Distraction osteogenesis was first described in 1905 by Codivilla who used this principle to elongate the femur. The Russian surgeon Ilizarov, the “father of modern distraction osteogenesis” repaired complex fractures and nonunions of long bones. In 1992, this priniciple was applied to craniofacial surgery by McCarthy who used distraction to lengthen the mandible via external fixators.

It has been shown that the stimulus of stretching activates the forces of spontaneous healing of the bone, producing new callus as the bone is lengthened. One of the many advantages of distraction is the stimulation of histogenesis in which the surrounding soft tissue is stretched and augmented along with the adjacent bone. The resulting slow change allows for a better adaptation of the soft tissue.

We describe a technique using the principles of distraction osteogenesis to provide sternal coverage in a thoracopagus twin who had failed previous reconstructive attempts.

Materials and Methods: Single-lumen endotracheal anesthesia is used with the patient in supine position. Two transverse incisions are made between the anterior and mid-axillary lines in the intercostal space between ribs three and four and ribs five and six. The skin, subcutaneous tissue and muscles overlying the chest wall are elevated. The ribs are then separated from the surrounding intercostal muscle as well as the underlying rib bed, preserving as much periosteum as possible.

Osteotomies are made approximately three centimeters distal to the costochondral junction. A 30 mm MicroZurich distractor (KLS-Martin, Jacksonville, FL) is then secured to the cut ends of the rib.

Once the device is tested and found to be functional, a drain is placed into the surgical wound that is then primarily closed.

Summary: Thoracopagus twins constitute approximately 74% of all conjoined twins. Infants of this form face one another and have the major junction at the level of the chest, with conjoined hearts and livers, as well as the upper gastrointestinal tract.

A number of techniques have been described to address the resultant defect after the separation of conjoined twins. Many of these utilize a combination of expanded skin and various allogenic materials including methylmethacylate.

This method of closing a sternal defect in a thoracopagus conjoined twin is not likely to be useful at the time of separation; it is a good option for those who have failed repeated efforts at sternal reconstruction. It allows the usage of solely autogenous materials in a young patient.

This technique also has the potential to be applied to conditions of thoracic insufficiency. There are a number of congenital and acquired disorders that result in a deficiency of the thoracic space. Various options have been described to address some of these problems. For those that are strictly a volume issue such as Jeune syndrome, Barnes syndrome and thoracic insufficiency syndrome, vertical expansion using the vertical expandable prosthetic titanium rib (VEPTR) implant is an option. However, this method does not address deficits in a horizontal dimension. Lateral thoracic expansion (LTE) has been described for use in children with Jeune syndrome. This entails dividing the ribs in a staggered fashion, opposing the long ends, and securing them with titanium plates.

Both of these reconstructive options result in the implantation of foreign bodies. Our method of distraction osteogenesis expands the thoracic cavity without the retention of allogenic implants.