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Distraction of the mandible and craniofacial skeleton
4 Journal of Cranio-MaxillofacialSurgery be described. Long-term clinical and cephalometric findings in 23 fetuses who underwent the fetal cleft lip procedure, were bom alive and survived until completion of growth will be reviewed. The surgically created cleft lip created and repaired in fetal rabbits resulted in healing without scar formation. The deformity varied from an incomplete to a severe complete cleft, assembling the clinical human spectrum of cleft lip. Cephalometric studios indicated that there were no statistically significant differences in premaxillary width, anterior maxillary length or anterior and posterior maxillary width among control, unrepaired, and repaired animals. Preliminary data from the craniosynostosis, calvarial bone defect and hemifacial microsomia models will be presented.
Distraction of the Mandible and Craniofacial Skeleton McCarthy J.G. Institute of Reconstructive Plastic Surgery, New York University Medical Center, New York, USA Distraction osteogenesis was pioneered by Professor Ilizarov of Russia. Over several decades, he practiced the technique extensively in the reconstruction of various defects and deformities of the long bones of the upper and lower extremities. Based on his contributions in the enchondral bones of the extremities, my colleagues and I at the Institute of Reconstructive Plastic Surgery of the NYU Medical Center began a series of experiments with the technique on the membranous bones of the canine craniofacial skeleton. In our preliminary experiment, an osteotomy was made at the angle of the mandible on one side. A mini lengthening device was then applied across the osteotomy and distraction initiated at postoperative day number 7. In a series of dogs, we demonstrated that the technique was effective in lengthening the mandible and this was documented by the development of a cross bite and radiographic findings of new bone formation. In a second experiment we conducted a serial study at the distraction site and documented that there were four temporal zones of distraction. The first zone (fibrous tissue) was characterized by the laying down of collagen in a linear fashion, parallel to the long axis of the distracted bone. In the second zone (bone formation) osteoblasts were demonstrated in close contact with the fibroblasts in the above mentioned collagen. New bone formation could readily be detected. In the third zone (bone remodelling) there was evidence of remodelling of the newly formed bone by the appearance of multi-nucleated osteoclasts. Finally, in the fourth zone (mature bone) there was the formation of dense, compact bone, indistinguishable in appearance from the adjacent non-distracted bone. Based on these laboratory experiments in the dog, we commenced a clinical programme of distraction of the human mandible in May, 1989. Since that time, we have successfully distracted 36 mandibles. The technique has been applied on 19 males and 17 females. The average age at the time of distraction was 5.9 years with a range in age from 1.5-21 years. The technique was applied unilaterally in 23 patients and bilaterally in 13 patients. The average amount of distraction was 23 mm. The diagnoses were craniofacial microsomia, developmental micrognathia, Treacher Collins syndrome and Nager syndrome, What we quickly learned was that we were achieving a multidimensional type of augmentation of the mandible, a type of reconstruction which is not achieved by traditional
orthognathic techniques. There are two unique properties of distraction osteogenesis. The technique is applied in a gradual fashion (1 ram/day) unlike the rapid expansion which occurs in traditional surgical techniques. Secondly, there is concomitant lengthening of the associated soft tissues including muscles, nerves and skin ('functional matrix'). Consequently, in our longitudinal follow-up studies, we have documented no evidence of relapse, a finding which stands in contrast to the experience in traditional orthognathic surgical mandibular advancement. We have also conducted experiments on distraction of other components of the craniofacial skeleton. In a canine experiment, osteotomies were made at two points in the zygomatic arch. A specially designed distraction device was placed on the adjacent components of the zygomatic complex and the intervening osteotomized segment was distracted at right angles to the longaccess of the bone. This experiment proved that the membranous bones of the craniofacial skeleton can be distracted at right angles to the long axis and that the zygomatic complex is amenable to surgical distraction. The findings were documented by photographs, cephalograms and three dimensional computer tomography scans. In immature dogs, distraction devices were placed across the nasofrontal and zygomaticomaxillary sutures without osteotomies. Active distraction was commenced on the day following surgery and the dogs demonstrated evidence of bilateral enopthalmos and anterior crossbite. These experiments demonstrated that the entire midface complex is amenable to distraction and that in immature animals osteotomies are not necessary. in a follow-up canine experiment, we have recently documented that Le Fort IIi osteotomy could be performed through limited incisions via an endoscope and distraction devices applied, The osteotomies were not completed through the medial orbital wall and nasal bones in order to reduce blood loss and obviate the need for blood transfusions. These experiments documented that Le Fort III osteotomies could be performed through small incisions via the endoscope without attendant wide dissection and blood loss. In addition, incomplete osteotomies also reduced the amount of blood loss. These are techniques that will eventually be applied to the human, significantly reducing the length of hospitalization and operating time. Distraction osteogenesis is a new craniofacial surgical technique which holds considerable promise in simplifying craniofacial surgical reconstruction, in reducing the length of hospitalization and attendant morbidity and in giving superior surgical results with reduced relapse rates.
References 1. Karp, N.S., CH. Thorne, J.G. McCarthy, H.A. Sissons Bone lengthening in the craniofacial skeleton. Ann. Plast. Surg. 24 (1994) 231 2. Karp, N.S., J.G. McCarthy, J.S. Schreiber et al. Membranous bone lengthening: a serial histologic study. Ann. Plast. Surg. 29 (1992) 2 3. McCarthy, J.G, J.G. Schreiber, N.S. Karp et.al. Lengthening of the human mandible by gradual distraction. Plast. Reconstr. Surg. 89 (1992) 1 4, Glat. P.M., D.A. Staffenberg, NS. Karp , P~A. Holliday, J. G McCarthy Multidimensional distraction osteogenesis: the canine zygoma. Plast. Reconstr. Surgl 94 (1994) 753 5. Staffenberg. D.A., R.J. Wood, J. G McCarthy et al. Midface distraction or advancement in the canine without osteotomies. Ann. Plast. Surg. 34 (1995) 512 6. McCarthy, J.G., Unpublished material, 1996.
Distraction of the Mandible and Craniofacial Skeleton McCarthy J.G. Institute of Reconstructive Plastic Surgery, New York University Medical Center, New York, USA Distraction osteogenesis was pioneered by Professor Ilizarov of Russia. Over several decades, he practiced the technique extensively in the reconstruction of various defects and deformities of the long bones of the upper and lower extremities. Based on his contributions in the enchondral bones of the extremities, my colleagues and I at the Institute of Reconstructive Plastic Surgery of the NYU Medical Center began a series of experiments with the technique on the membranous bones of the canine craniofacial skeleton. In our preliminary experiment, an osteotomy was made at the angle of the mandible on one side. A mini lengthening device was then applied across the osteotomy and distraction initiated at postoperative day number 7. In a series of dogs, we demonstrated that the technique was effective in lengthening the mandible and this was documented by the development of a cross bite and radiographic findings of new bone formation. In a second experiment we conducted a serial study at the distraction site and documented that there were four temporal zones of distraction. The first zone (fibrous tissue) was characterized by the laying down of collagen in a linear fashion, parallel to the long axis of the distracted bone. In the second zone (bone formation) osteoblasts were demonstrated in close contact with the fibroblasts in the above mentioned collagen. New bone formation could readily be detected. In the third zone (bone remodelling) there was evidence of remodelling of the newly formed bone by the appearance of multi-nucleated osteoclasts. Finally, in the fourth zone (mature bone) there was the formation of dense, compact bone, indistinguishable in appearance from the adjacent non-distracted bone. Based on these laboratory experiments in the dog, we commenced a clinical programme of distraction of the human mandible in May, 1989. Since that time, we have successfully distracted 36 mandibles. The technique has been applied on 19 males and 17 females. The average age at the time of distraction was 5.9 years with a range in age from 1.5-21 years. The technique was applied unilaterally in 23 patients and bilaterally in 13 patients. The average amount of distraction was 23 mm. The diagnoses were craniofacial microsomia, developmental micrognathia, Treacher Collins syndrome and Nager syndrome, What we quickly learned was that we were achieving a multidimensional type of augmentation of the mandible, a type of reconstruction which is not achieved by traditional
orthognathic techniques. There are two unique properties of distraction osteogenesis. The technique is applied in a gradual fashion (1 ram/day) unlike the rapid expansion which occurs in traditional surgical techniques. Secondly, there is concomitant lengthening of the associated soft tissues including muscles, nerves and skin ('functional matrix'). Consequently, in our longitudinal follow-up studies, we have documented no evidence of relapse, a finding which stands in contrast to the experience in traditional orthognathic surgical mandibular advancement. We have also conducted experiments on distraction of other components of the craniofacial skeleton. In a canine experiment, osteotomies were made at two points in the zygomatic arch. A specially designed distraction device was placed on the adjacent components of the zygomatic complex and the intervening osteotomized segment was distracted at right angles to the longaccess of the bone. This experiment proved that the membranous bones of the craniofacial skeleton can be distracted at right angles to the long axis and that the zygomatic complex is amenable to surgical distraction. The findings were documented by photographs, cephalograms and three dimensional computer tomography scans. In immature dogs, distraction devices were placed across the nasofrontal and zygomaticomaxillary sutures without osteotomies. Active distraction was commenced on the day following surgery and the dogs demonstrated evidence of bilateral enopthalmos and anterior crossbite. These experiments demonstrated that the entire midface complex is amenable to distraction and that in immature animals osteotomies are not necessary. in a follow-up canine experiment, we have recently documented that Le Fort IIi osteotomy could be performed through limited incisions via an endoscope and distraction devices applied, The osteotomies were not completed through the medial orbital wall and nasal bones in order to reduce blood loss and obviate the need for blood transfusions. These experiments documented that Le Fort III osteotomies could be performed through small incisions via the endoscope without attendant wide dissection and blood loss. In addition, incomplete osteotomies also reduced the amount of blood loss. These are techniques that will eventually be applied to the human, significantly reducing the length of hospitalization and operating time. Distraction osteogenesis is a new craniofacial surgical technique which holds considerable promise in simplifying craniofacial surgical reconstruction, in reducing the length of hospitalization and attendant morbidity and in giving superior surgical results with reduced relapse rates.
References 1. Karp, N.S., CH. Thorne, J.G. McCarthy, H.A. Sissons Bone lengthening in the craniofacial skeleton. Ann. Plast. Surg. 24 (1994) 231 2. Karp, N.S., J.G. McCarthy, J.S. Schreiber et al. Membranous bone lengthening: a serial histologic study. Ann. Plast. Surg. 29 (1992) 2 3. McCarthy, J.G, J.G. Schreiber, N.S. Karp et.al. Lengthening of the human mandible by gradual distraction. Plast. Reconstr. Surg. 89 (1992) 1 4, Glat. P.M., D.A. Staffenberg, NS. Karp , P~A. Holliday, J. G McCarthy Multidimensional distraction osteogenesis: the canine zygoma. Plast. Reconstr. Surgl 94 (1994) 753 5. Staffenberg. D.A., R.J. Wood, J. G McCarthy et al. Midface distraction or advancement in the canine without osteotomies. Ann. Plast. Surg. 34 (1995) 512 6. McCarthy, J.G., Unpublished material, 1996.