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Distraction osteogenesis for craniosynostosis.

OBJECT: The authors describe the use of distraction devices and surgical techniques of distraction osteogenesis for the treatment of patients with craniosynostosis. METHODS: Since 1994, the authors have performed distraction procedures in 23 patients with craniosynostosis in whom osteogenesis was achieved. Thirteen of the 23 patients underwent a complete Le Fort III midface osteotomy and distraction. In 10 patients the distraction osteogenesis involved the cranial bone; six underwent combined forehead and midface distraction (Le Fort IV distraction) in which multiple internal devices were used after performing a Le Fort IV osteotomy. An external distraction procedure was used to treat the first two cases. Since 1996, the authors have used internal devices developed in their unit. Distraction was initiated 1 week after the osteotomy at the rate of 0.5 mm per day for the cranium and 1.0 mm per day for the midface. The consolidation phase after distraction was initiated was 2 to 3 months. No major complications such as intracranial infection or neurological deficits were observed during the course of distraction osteogenesis. The osteogenesis generated at the distraction site was considerably satisfactory; and recurrence of the deformity in the follow-up period was minimal. CONCLUSIONS: Distraction osteogenesis for craniofacial deformity has numerous advantages: 1) bone grafting is unnecessary; 2) the procedure is less invasive, has short operating time, and less blood loss occurs than in conventional craniofacial procedures; 3) no intracranial dead space is created; 4) there is a good amount of blood flow to the bone segment; and 5) soft-tissue expansion occurs. The authors believe that distraction osteogenesis is a versatile and stable option for the treatment of patients with craniosynostosis.

Adolescent↗

Assessment of cell proliferation during mandibular distraction osteogenesis in the maturing rat.

INTRODUCTION: The cellular mechanisms controlling distraction osteogenesis are not well understood. The purpose of this study was to examine the role of cell proliferation in the regulation of mandibular distraction osteogenesis. METHODS: Unilateral mandibular ramus osteotomies were performed on 125 3-month-old Sprague-Dawley rats. The rats were randomized into 4 distraction rate groups and distracted for 5 days after 3-day latency. Rats (7 or 8 from each rate group) were killed at 4 time points. The rats received 5-bromo-2-deoxyuridine (BrdU) injections (40 mg per kilogram, i.p.) at day 3 (end of latency). RESULTS: Both intramembranous and endochondral ossification was seen in the osteogenesis area. BrdU+ mesenchymal progenitor cells were significantly higher at day 10 (P <.05) and were found most numerously around the sagittal middle portion of the gap (P <.01). The greatest numbers of BrdU+ osteocytes were seen at day 38 (P <.05). Both BrdU+ osteoclasts and chondrocytes peaked at day 24. CONCLUSIONS: Mesenchymal progenitor cells are mostly recruited in the early consolidation period, but they decrease in the middle and late consolidation periods during mandibular distraction osteogenesis. The rapid rate might suppress or sustain the proliferation and differentiation of mesenchymal progenitor cells during mandibular distraction osteogenesis. BrdU+ cells can survive throughout the entire experimental period of 5 weeks.

Animals↗

The use of distraction osteogenesis to treat hemifacial microsomia: a clinical report.

Distraction osteogenesis is a method of forming bone through osteotomy and sequential stretching of the healing callus. This process is accomplished with the aid of a distraction device, which is secured with screws placed directly into bone for a predetermined length of time. This clinical report describes the use of distraction osteogenesis to treat mandibular asymmetry in a patient with Goldenhar's syndrome, a form of hemifacial microsomia. After treatment, the patient had a more rounded facial contour and corrected occlusal plane.

Bone Screws↗

Mandibular symphyseal distraction osteogenesis: review of three techniques.

Mandibular symphyseal distraction osteogenesis (MSDO) is an alternative strategy to correct mandibular transverse deficiencies and dental crowding. Only a limited number of practitioners have reported their clinical experience and potential complications of this procedure to widen the mandible in a large case series. This study involved retrospective analysis of 40 patients who underwent mandibular symphyseal distraction osteogenesis. Three different types of distractor were used to widen the mandible: tooth-borne in 21 patients, bone-borne in 5 patients and hybrid (both bone and tooth-borne) in 14 patients. The distraction amount ranged from 7 to 11 mm (mean 7.31 mm). While 39 patients underwent successful mandibular symphyseal distraction, there was one failure. Most of the complications were experienced in bone-borne distractors, such as breakage of the distractor rod, gingival recession, secondary infection and ptosis of the chin. In the light of these findings, it is suggested that a lingually placed tooth-borne hyrax appliance is more suitable and reliable than the other distraction devices. Further larger studies are needed in order to better evaluate the effectiveness of bone-borne or hybrid devices.

Adolescent↗

Simultaneous maxillary and mandibular distraction osteogenesis with a semiburied device.

Distraction osteogenesis is a technique utilizing natural healing mechanisms to generate new bone; it is commonly used to lengthen the hypoplastic mandible. Distraction of the maxilla and mandible as a unit is an obvious extension of the technique. We describe the application of a semiburied distractor to simultaneously lengthen the mandible and maxilla and level a canted occlusal plane in three cases. The indications for bimaxillary distraction are reviewed, including its advantages, disadvantages and limitations.

Adolescent↗

Limb salvage using distraction osteogenesis. A classification of the technique.

We report the results of distraction osteogenesis (callotasis) for the reconstruction of extensive defects after the excision of skeletal tumours in the limbs. Bone transport was performed in ten patients (five osteosarcomas and five giant-cell tumours), shortening-distraction in three (two osteosarcomas and one Ewing's sarcoma), and distraction osteogenesis combined with an intramedullary nail to reduce the time of external fixation in six (three osteosarcomas, two chondrosarcomas, and one malignant fibrous histiocytoma). The mean length of the defects after excision of the lesion was 8.4 cm. The mean external fixation index was 39.5 days/cm for the group treated by bone transport, 34.1 days/cm for the shortening-distraction group, and 24.0 days/cm for the group treated by distraction and an intramedullary nail. Functional evaluation gave excellent results in 12 patients, good in five and fair in two. There were ten complications in 19 patients, all of which were successfully treated. We also classified reconstruction using distraction osteogenesis into five types based on the location of the defects after resection of the tumour: type 1, diaphyseal; type 2, metaphyseal; type 3, epiphyseal; type 4, subarticular reconstruction; and type 5, arthrodesis. Our results suggest that reconstruction using distraction osteogenesis provides bone which will develop sufficient biomechanical strength and durability. It is beneficial in patients with an expectation of long-term survival and in growing children.

Adolescent↗

Clinical assessment of 40 patients subjected to alveolar distraction osteogenesis.

Alveolar bone distraction is a technique used to restore vertical defects in the edentulous alveolar ridge. The gradual growth of bone tissue has a predictable result, allowing the placement of an osseointegrated implant in an ideal position. In this study, the effectiveness of the alveolar distraction technique was verified, using an extraosseous device. The bone augmentation average was 9.5 mm in 40 patients, showing a 92.5% success rate.

Alveolar Process↗

Premaxillary distraction osteogenesis with an individual tooth-borne appliance.

Distraction osteogenesis defines a technique of bone generation and osteosynthesis by the distraction of native preexisting bone. The technique offers a promising treatment alternative for patients with maxillary hypoplasia and a retrognathic mandible. In this case report, the steps in the treatment of an 18.2-year-old girl with premaxillary hypoplasia and anterior crossbite are described. The patient was treated with a distraction osteogenesis technique, and premaxillary advancement was performed using an individual tooth-borne distraction device. The surgical operation consisted of a classical segmental maxillary osteotomy carefully respecting the palatal periosteum. The distractor was cemented in the mouth after the surgical procedures. The patient was observed during a seven-day latency period, after which the device was activated 0.5 mm every 12 hours. The anterior crossbite was eliminated in one week, and the treatment was finished with fixed orthodontic appliances.

Adolescent↗

Zoledronic acid prevents osteopenia and increases bone strength in a rabbit model of distraction osteogenesis.

UNLABELLED: Prolonged healing times and stress-shielding osteopenia remain problematic in distraction osteogenesis. In this study of 30 rabbits, zoledronic acid increased regenerate volume, mineralization, and tibial strength and prevented osteopenia over a 6-week period. Translation to the clinical setting, if safe, could improve outcomes in distraction osteogenesis in children. INTRODUCTION: Because the external fixators for limb lengthening and reconstruction are designed to control the positions of bone fragments accurately, they also produce stress-shielding effects on the forming regenerate and surrounding bone. Osteopenia, leading to refracture and limitations on rehabilitation, are common consequences, potentially increasing morbidity and detracting from final clinical outcome. MATERIALS AND METHODS: We examined the effect of zoledronic acid on distraction osteogenesis in 42 immature male NZW rabbits. The model chosen results in reliable regenerate formation and stress-shielding osteopenia. Fourteen animals received either Saline, zoledronic acid 0.1 mg/kg at surgery (ZOL), or another dose 2 weeks postoperatively (Redosed ZOL). Rabbits underwent DXA for bone mineral content and bone mineral density in regenerate and surrounding segments of operated and contralateral tibias. After death at 6 weeks, 30 pairs of tibias underwent quantitative computerized tomography (QCT) and four-point bend testing, and 12 were examined by histomorphometry. The study was powered at 0.8 to show differences of 1.3 SDs for mineral and mechanical parameters. RESULTS: Osteopenia observed in tibias of the Saline group was absent in ZOL and Redosed ZOL tibias, the latter exhibiting higher bone mineral density and bone mineral content over contralateral regions (p < 0.01). Regenerate bone mineral content was higher in ZOL and Redosed ZOL versus Saline groups at 4 and 6 weeks (p < 0.01). Cross-sectional area was 49% and 59% greater at 6 weeks in ZOL and Redosed ZOL regenerates compared with the Saline group (p < 0.01). ZOL and Redosed ZOL tibias were 29% and 89% stronger by four-point bending than the Saline group (p < 0.01). Histomorphometry in the regenerate of ZOL and Redosed ZOL groups revealed higher trabecular bone volume and trabecular number compared with the Saline group (p < 0.001). CONCLUSIONS: Zoledronic acid administration led to significantly greater bone area, mineral content, strength, and trabecular number with reduced stress-shielding osteopenia in this model of distraction osteogenesis. These data suggest that intraoperative and postoperative zoledronic acid administration could improve outcomes in children undergoing limb lengthening.

Animals↗

[Initial outcome of vertical distraction osteogenesis of the atrophic alveolar ridge].

Besides several conventional therapeutic regimens to treat severe forms of alveolar ridge atrophy the distraction osteogenesis is an alternative method. We introduced a new technique for the treatment of alveolar ridge atrophy encouraged by the advantages of distraction osteogenesis in the last decade. A new technique called "vertical distraction osteogenesis (VDO)" has been developed by our study group to move dentolous and edentolous segments of the alveolar process vertically with a device in microplate-design. Vertical distraction osteogenesis was completed successfully in nine patients with segments length ranging from 6.5 mm to 43 mm with an average of 23.7 mm. The vertical distraction rate was 9.9 mm on average in seven mandibular and two maxillar segments. In all cases we found good stability and the predicted movement of the segments. In contrast to bone transplantation an earlier mineralization in the vertically distracted area could be seen by radiological examination and biopsy. Five patients were treated with dental implants 12 weeks after distraction procedure. Main advantages of vertical distraction osteogenesis are: 1. No bone harvesting, 2. decreased resorption tendency, 3. lower morbidity compared with conventional techniques, 4. lower infection rate and 5. feasibility to insert dental implants 12 weeks after distraction procedure, 6. gain of soft tissue.

Adolescent↗

[Biomechanical studies of forces occurring in the Ilizarov and Orthofix apparatuses during limb lengthening by distractive osteogenesis].

The magnitude of the distractive forces occurring in the Ilizarov and Orthofix apparatuses during limb lengthening by distractive osteogenesis has been investigated. Eighteen patients treated between 1995 and 1998 were included in the study. The data obtained were computerized and related to clinical, radiographic and sonographic findings. Typical and repeatable graphs of forces were found during the process of lengthening as well as typical relationships between the callus and the values of distractive forces.

Biomechanical Phenomena↗

Longitudinal results of mandibular distraction osteogenesis in hemifacial microsomia.

The aim of this study was to evaluate mandibular distraction therapy by three-dimensional (3-D) computed tomography (CT) imaging so as to be able to improve the treatment results. The study group consisted of eight children (3 male and 5 female) with hemifacial microsomia. For each child, CT scans of the head were available (Pro Speed S Fast Spiral scanner; General Electric). Longitudinal measurements of the mandible, bony and soft tissue 3-D reconstructions, and masticatory muscles were demonstrated. Three-dimensional CT scans provide important data concerning the results of mandibular distraction therapy and should be used in treatment evaluation. In some patients and for some muscles only, a small increase in the volume of the affected side of the masticatory muscles in comparison to the normal side was found 3 years after mandibular distraction. In around 50% of the cases, there seems to be a relapse occurring 1 year after distraction osteogenesis, and this relapse has a progressive character when seen 3 years after distraction osteogenesis in comparison to 15 weeks after distraction osteogenesis.

Adolescent↗

Distraction osteogenesis for the reconstruction of the temporomandibular joint.

Distraction osteogenesis is the technique of slow bone expansion across an osteotomy site. Most commonly used for orthopedic lengthening of the extremities, it is now being applied to the craniofacial skeleton, including treatment of facial asymmetries, micrognathias and mandibular discontinuity defects. The technique can also be applied for the reconstruction of a neo-condyle. Transport distraction osteogenesis may prove to be a treatment alternative for patients requiring condylar reconstruction.

Adult↗

Changes in parathyroid hormone-related protein and 3-dimensional trabecular bone structure of the mandibular condyle following mandibular distraction osteogenesis in growing rats.

PURPOSE: Distraction osteogenesis (DO) is commonly performed for mandibular reconstruction during the growth period. We tested the hypothesis that parathyroid hormone-related protein (PTHrP) in mandibular condylar cartilage and underlying trabecular bone in growing individuals undergo changes in response to distraction forces. MATERIALS AND METHODS: Forty-eight 6-week-old male Sprague-Dawley rats were used. Animals underwent unilateral mandibular distraction using a distractor that we devised, and unoperated animals were evaluated as controls. DO procedure was performed: 3 days' latency period, 0.4 mm/day rate, total 4.0 mm. Changes in cartilage morphology, PTHrP activity, and 3-dimensional trabecular bone structure changes measured by micro-computed tomography were examined at 0, 2, 4, and 6 weeks of consolidation. RESULTS: A marked irregularity was noted in the superior portion of the distracted side's condylar cartilage that resolved after distraction ceased. PTHrP was more strongly expressed in the hypertrophic layer of condylar cartilage on the distracted side than in controls, up to 6 weeks after the end of distraction. Subchondral trabecular bone volume, percent bone volume, and trabecular number in the superior and posterior regions of the condyle decreased significantly by 2 weeks after distraction. These parameters returned to normal in the posterior condyle, but not in the superior part of the condyle by 6 weeks following distraction. CONCLUSION: These results suggest that unilateral mandibular distraction in growing rats causes temporary morphologic alterations of trabecular bone structure on the distracted side accompanied by increased production of PTHrP in the mandibular condyle.

Animals↗

[Distraction osteogenesis with a fully implantable system. Experimental study].

Distraction osteogenesis using external or intraoral devices is an established method for lengthening the human mandible. In this preliminary study on sheep, a completely implanted device for mandibular lengthening is presented. After osteotomy of the mandible, the electromechanical device was fixed to the mandible and the power and control unit were inserted subcutaneously in the neck region. After a healing period of 5 days, the device was activated magnetically and allowed calibrated distraction steps of 0.04 mm/h, achieving a total of 1.0 mm per day. With this method, it was possible to lengthen the mandible automatically over a period of 14 days without transmucosal activation. In our study, this newly designed internal device was successfully used for distraction osteogenesis, and a maximum mandibular lengthening of 13.6 mm was achieved. Further research is necessary to achieve progression to human clinical application in the near future.

Animals↗

[Intraoral distraction osteogenesis].

OBJECTIVE: To study the application of intraoral distraction osteogenesis in correction of various dentofacial deformities. METHODS: From 1997, 12 cases with various dentofacial deformities were corrected by using 6 kind of intraoral distractor. 3 cases of them were the patients with cleft palate who have severe secondary maxillary hypoplasia. 4 cases with hemifacial microsomia, 2 cases with micrognathia and 3 cases with partial mandibular defect. The maxillae were elongated from 10 mm to 15 mm, the mandibles were elongated from 15 mm to 25 mm, the vertical mandibular distraction was from 10-15 mm. RESULTS: All cases were corrected satisfactorily and have no any complications. In 1 case the distractor did not work during distraction and was replaced. Another case the mandibular margin fractured after distraction, the rigid fixation was performed for it. CONCLUSIONS: The intraoral distraction osteogenesis provides a new method with many advantages for those dentofacial deformities that are difficult correct by using ordinary orthognathic surgery.

Adolescent↗

Rat mandibular distraction osteogenesis: II. Molecular analysis of transforming growth factor beta-1 and osteocalcin gene expression.

Distraction osteogenesis is a powerful technique capable of generating viable osseous tissue by the gradual separation of osteotomized bone edges. Although the histologic and ultrastructural changes associated with this process have been extensively delineated, the molecular events governing these changes remain essentially unknown. We have devised a rat model of mandibular distraction osteogenesis that facilitates molecular analysis of this process. Such information has significant clinical implications because it may enable targeted therapeutic manipulations designed to accelerate osseous regeneration. In this study, we have evaluated the expression of transforming growth factor beta-1, a major regulator of osteogenesis during endochondral bone formation and development, and osteocalcin, an abundant noncollagenous extracellular matrix protein implicated in the regulation of mineralization and bone turnover. The right hemimandible of 36 adult male rats was osteotomized, and a customized distraction device was applied. Animals were allowed to recover and, after a 3-day latency period, were distracted at a rate of 0.25 mm twice daily for 6 days followed by a 2- or 4-week consolidation period. Distraction regenerate was harvested after the latency period, days 2, 4, or 6 of distraction, and after 2 or 4 weeks of consolidation and processed for Northern analysis (n = 4 at each time point) and immunohistochemical localization of TGF-beta1 (n = 2 at each time point). Six sham-operated animals (i.e., skin incision without osteotomy) were also killed (immediately postoperatively), and the mandibles were harvested and prepared in a similar fashion. Equal loading and transfer of RNA for Northern analysis was ensured by stripping and probing membranes with a probe against GAPDH (a housekeeping gene). Our results demonstrate that the spatial and temporal patterns of TGF-beta1 mRNA expression and protein production coincide with osteoblast migration, differentiation, and extracellular matrix synthesis. In addition, we demonstrate that TGF-beta1 production may be an important regulator of vasculogenesis during mandibular distraction osteogenesis. Finally, we have shown that osteocalcin gene expression coincides temporally with mineralization during rat mandibular distraction osteogenesis.

Animals↗

Experimental alveolar ridge augmentation by distraction osteogenesis using a simple device that permits secondary implant placement.

The purpose of this study was to develop an improved technique of alveolar ridge augmentation by distraction osteogenesis using distraction screws, and to investigate tissue reactions to titanium implants at the distraction site. The left mandibular premolars were extracted from 6 adult dogs. After 12 weeks, a box-shaped osteotomy of the alveolar bone was carried out, and distraction devices were placed on the transport and base segments. After a 7-day latency period, the alveolar bone was augmented by 7 mm vertically at a rate of 1.0 mm/day. Just after distraction, these devices were replaced with dental implants for fixation of the transport segment and bone formation of the distraction site. Histologic and radiographic evaluations were made at 8 and 12 weeks after distraction. Vertical augmentation averaged 6.1 mm after 12 weeks of consolidation. It was possible to lengthen the alveolar bone without great difficulty, and good bone formation was recognized in the distraction site. Greater integration between the implant and the distracted bone was observed at 12 weeks after distraction than at 8 weeks. Distraction osteogenesis was successfully applied to alveolar ridge augmentation by this improved technique, and the implants osseointegrated in the augmented ridge.

Alveolar Ridge Augmentation↗