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ANATOMICAL IRONY:
To mend difficult fractures // and correct deformities // bones are being wrenched apart // to help them heal.

Filling the Gap

By Anita Slomski // Illustrations by Daniel Chang // Summer 2008
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Distraction osteogenesis

In the realm of scientific discovery, distraction osteogenesis qualifies more as happenstance than intentional innovation. Who knows whether anyone would ever have tried to pull a fractured bone apart to get it to heal if a patient hadn’t accidentally reversed the tightening rod that was supposed to push together the ends of his fractured femur. And if the doctor who noticed the result—new bone filling in the gap between the separated segments—hadn’t been Gavriil Abramovich Ilizarov, surgeons might not have practiced this revolutionary tissue-engineering technique until decades later, if ever. “I might have told the patient, ‘Don’t do that again,’ but the genius of Ilizarov was that he wondered, ‘How can I get this to happen again?’” says J. Tracy Watson, chief of orthopedic traumatology at the St. Louis University School of Medicine.

Most of the world didn’t hear of Ilizarov’s technique, which he named distraction osteogenesis in 1951, for more than 30 years. A general practitioner, and a Jew, Ilizarov had been ordered off to the industrial city of Kurgan in Siberia to tend to the wounds of soldiers returning from the Second World War.

With so many patients suffering from bone infections and missing bone from bullet wounds, Ilizarov became an orthopedist by necessity. And with resources severely constrained, his distraction apparatuses were primitive. The external frame that encircled the outside of fractured bones was made from head gaskets cut from old tanks; the pins that he drilled through the fractured bone and affixed to the external frame were fashioned from bicycle spokes. By tightening the spokes, Ilizarov would slowly force the bone segments apart.

Experimenting on dogs, Ilizarov found that new bone would spontaneously form if broken bone was distracted at the rate of one millimeter per day—coincidentally, the same rate at which stretched nerves will regenerate. Distracting just 0.25 millimeters at a time, four times a day, worked even better and caused less pain. But the Cold War and a repressive medical bureaucracy kept Ilizarov’s discovery buried until 1967, when he cured the badly broken and infected tibia and fibula of Valery Brumel, a Soviet high jumper and Olympic gold medalist. Then, more than a dozen years later, Ilizarov used distraction to mend the infected tibia of the Italian mountaineer Carlo Mauri. That finally attracted the attention of European surgeons, and during a trauma fellowship in Switzerland, in 1986, Watson saw distraction osteogenesis being performed.

“I sneaked over to Germany and saw surgeons sticking piano wires into skin to pull apart bone,” he recalls. “I couldn’t believe what I was seeing. At first look, you had to say it was insane.”

For years, that was the consensus among Western doctors—that distraction osteogenesis was the antithesis of rational medical practice. In 1987, when Watson, then at the Cleveland Clinic, used the technique to save the leg of a patient whose badly fractured tibia had refused to heal, a senior doctor termed the procedure “the tool of the devil.” But Watson and other orthopedists, including James Aronson, director of the Laboratory for Limb Regeneration Research and chief of pediatric orthopedics at Arkansas Children’s Hospital in Little Rock, pursued the technique. Ilizarov (accompanied by KGB agents) eventually traveled to the United States, and two dozen American doctors, including Watson and Aronson, visited his institute in the USSR, where they operated on Soviet patients. Slowly the approach gained acceptance, and today distraction osteogenesis is used to treat some of the most challenging orthopedic conditions: fractures that won’t mend, limb deformities and bone defects from trauma, infection or cancer.

Theoretically, any bone can be distracted, and in Russia, surgeons actually distract the skull after a stroke with something “that looks like a medieval torture device,” Watson says. “Distraction causes microcapillaries to form and creates a new blood supply to the area. So by freeing up small sections of bone over the area of the brain that has sustained the stroke, you increase the blood flow. But of course, we’d be probably thrown out of the hospital if we tried that treatment here.”

For defects elsewhere in the head, however, maxillofacial and plastic surgeons have enthusiastically embraced distraction. “It has revolutionized and simplified craniofacial surgery,” says Joseph McCarthy, professor of plastic surgery and director of the Institute of Reconstructive Plastic Surgery at New York University Langone Medical Center. McCarthy performed the first craniofacial distraction procedure in 1989 and now does at least 50 a year to correct such defects as cleft palate, malformed jaws that interfere with breathing and Crouzon syndrome, in which premature fusion of skull bones prevents the skull and facial bones from developing normally. “For children with Crouzon syndrome, for example, we can use distraction to move the upper jaw, the cheekbones, the nose and the eye sockets in one block,” McCarthy says.

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Making Bone Grow Faster

Speeding up distraction’s consolidation phase would make the procedure easier to bear. Several approaches seem promising.

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hed-dossier

1. “Basic Science and Biological Principles of Distraction Osteogenesis,” by James Aronson, in Limb Lengthening and Reconstruction Surgery, eds. S. Robert Rozbruch and Svetlana Ilizarov (New York: Informa Healthcare, 2006). In this textbook chapter, Aronson describes a variety of his discoveries, including the fact that speeding up the rate of distraction beyond two millimeters per day led to poor bone formation.  

2. “Mandibular Advancement by Distraction Osteogenesis for Tracheostomy-Dependent Children With Severe Micrognathia,” by Derek M. Steinbacher, Leonard B. Kaban and Maria J. Troulis, Journal of Oral and Maxillofacial Surgery, August 2005. Study demonstrates that distracting the jawbone with a semi-buried device can eliminate the need for an artificial airway.

3. “Craniofacial Bone Tissue Engineering,” by Derrick C. Wan, Randall P. Nacamuli and Michael T. Longaker, Dental Clinics of North America, April 2006. Reviews research into enhancing distraction osteogenesis as well as advances in cell-based tissue engineering for cases in which bone cannot be reconstructed with distraction.

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