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PubMed2004

Injected calcium sulfate for consolidation of distraction osteogenesis in rabbit tibia.

This study investigated the effects of calcium sulfate powder injection in a rabbit tibial distraction model. There was one experimental group and two control groups. The calcium sulfate powder, suspended in carboxymethylcellulose (CMC) medium, was injected into the distracted tissue in the experimental rabbit group, whereas only CMC medium was injected into the one control group. The other control group did not undergo any intervention. On radiography and bone mineral density tests, the amount of newly formed bone was greater in the distracted zone of the experimental group than in the two control groups, which showed incomplete bone deposition and calcification. The application of calcium sulfate to distracted tissue increased the rate of osteogenesis and calcification.

Animals↗
PubMed2003

Management of stiff hypertrophic nonunions by distraction osteogenesis: a report of 16 cases.

OBJECTIVE: Hypertrophic nonunions can be managed successfully with distraction. Hypertrophic changes indicate that the tissue at the nonunion site has a biologic healing potential. The missing component is an appropriate mechanical environment to transform a hypertrophic nonunion into solid bone. DESIGN: At our institution, the records of 10 male and 6 female patients treated for stiff hypertrophic nonunion with the Ilizarov distraction method were retrospectively analyzed. The average age of the patients was 42.3 years (range 15-69 years). The nonunion time ranged from 8-48 months. All patients had at least 1 cm shortening, 3 patients had a deformity in one plane, and 13 had a deformity in two planes. The pathology was localized to the upper extremity in 5 patients, to the lower extremity in 11 patients, with a periarticular localization in 11 patients. An Ilizarov-type circular external fixator was applied in all patients to correct shortening, to correct deformity, and to achieve a solid union. RESULTS: All nonunions healed at an average follow-up of 38.1 months (range 24-95 months). The average time spent in the external fixator was 7.1 months (range 5-10 months). The average preoperative length discrepancy was 2.25 cm (range 1-8 cm), which was eliminated in all patients at the time of frame removal. The average coronal plane angulation of 19.7 degrees (range 15-37 degrees) and sagittal plane angulation of 20.8 degrees (range 5-45 degrees), together with translation in one patient, also were corrected to normal anatomic alignment. Complications included minor pin tract infections and hardware problems; recurrence of deformity was observed in one patient who refused to wear a protective brace after frame removal. CONCLUSIONS: Hypertrophic nonunions can be managed successfully with distraction. The Ilizarov device can address every aspect of a stiff hypertrophic nonunion, including shortening and deformity.

Adolescent↗
PubMedDate not supplied

Use of horizontal alveolar distraction osteogenesis for implant placement in a narrow alveolar ridge: a case report.

Although alveolar distraction is a promising method for ridge augmentation involving the atrophic maxilla or mandible for implant placement, techniques of horizontal and oblique alveolar distraction for expanding a narrow alveolar ridge have not been established. A case of horizontal alveolar distraction for implant placement using a titanium mesh plate and a distraction screw is reported. Horizontal alveolar distraction was performed on a patient with an extremely atrophic alveolar ridge in the anterior mandibular region. Two transport segments using horizontal osteotomies were prepared, and 2 horizontal alveolar distraction devices were inserted. After a 7-day waiting period, the devices were activated and alveolar widening was performed labially (0.225 mm twice a day for 14 consecutive days). Three months after consolidation, the distraction devices were removed. The distracted areas were completely filled with newly formed solid bone tissue. Two months after the device was removed, 4 endosseous implants were placed and an implant-supported definitive prosthesis was placed. This method of horizontal alveolar distraction appears to be clinically useful for the placement of implants in atrophic or knife-edged alveolar ridges.

Alveolar Process↗
PubMed2003

[Expression of vascular endothelial growth factor during mandibular distraction osteogenesis in rabbits].

OBJECTIVE: To investigate the expression pattern of vascular endothelial growth factor (VEGF) in the distracted callus during mandibular osteodistraction. METHODS: Bilateral mandibular osteotomies were performed in 12 rabbits. 3 rabbits were sacrificed respectively at 0, 7, 14 and 28 days after completion of distraction. The newly formed calluses were harvested and processed for histology and immunohistochemistry of VEGF. RESULTS: Intense angiogenesis was observed in the regenerated callus after mandibular lengthening, and positive staining for VEGF was mainly noted in vascular endothelial cells and the active osteoblasts. CONCLUSIONS: Mechanical strain created by distraction led to angiogenesis in distraction gap. VEGF may play a critical role in angiogenesis and subsequent osteogenesis during mandibular lengthening.

Animals↗
PubMed2003

[Distraction osteogenesis for correction of maxillo-mandibular deformity].

OBJECTIVE: To study the application of extraoral distraction devices in correction of various maxillo-mandibular deformities. METHODS: From 1997, 11 cases with various maxillo-mandibular deformities were corrected by distraction devices of designed by myself. 7 cases of then were the patients with cleft palate who have severe secondary maxillary hypoplasia. 1 case with micrognathia, 1 case with partial mandibular mentum defect, 1 case with lateral deviation of micrognathia and 1 case with hemimandibular hypertrophy. The mandibles were elongated, from 12 mm to 20 mm, the maxillae were elongated from 7 mm to 22 mm, the vertical mandibular distraction was 15 mm. RESULTS: All cases were corrected satisfactorily and haven't any complications. In 1 cases the 1 Kischners pin had been pull out by loosen during distration. 4 Kischners pin were curved during vertical mandibular distration. Another case the maxillary hypoplasia appeared edge-to-edge and mild open occlusion after 4 weeks fixation. CONCLUSION: The extraoral distration osteogenesis provides a new method with many advantages for those maxillo-mandibular deformities that are difficulty corrected by ordinary orthognathic surgery.

Cleft Palate↗
PubMed2004

Craniofacial reconstruction by transport distraction osteogenesis: corticotomy versus osteotomy--an experimental study.

Transport osteogenesis is a modified technique of callus distraction appropriate for the reconstruction of extended osseous defects of long or flat bones. The aim of this study was to determine the regenerative potential of this technique related to the degree of mobilization of the transport segment. In 10 adult sheep, critically sized defects of the calvaria were treated by gradual movement of a transport segment consisting of calvarial bone. The transport segments were either corticotomized (n = 5) or osteotomized (n = 5). The latency period was 5 days; the rate of distraction was 1 mm/d, extended for approximately 40 days. The consolidation period was 28 days. Specimens were investigated by conventional radiography, computed tomography scans, immunofluorescence, and histological examination. In both groups, transport osteogenesis resulted in a complete closure of the defect. The volume and thickness of newly formed bone at the defect site did not differ significantly between the groups, nor did the extent of vascularization. Bone formation and remodeling occurred during the entire period of distraction and consolidation. Osteotomized transport segments became smaller during distraction, whereas the volume of corticotomized segments remained relatively constant. In conclusion, transport osteogenesis resulted in reliable closure of extended skull defects in adult organisms; corticotomy and osteotomy of the transport segment led to a similar extent of bone formation.

Age Factors↗
PubMed2005

In vivo assessment of regenerate axial stiffness in distraction osteogenesis.

This paper presents an in vivo test for assessment of regenerate axial stiffness after the distraction phase of lengthening therapy. The test result supplements radiography in evaluating bone healing and assists in determining when the regenerate stiffness is sufficient for removal of the external fixator. The test is non-invasive and does not require fixator removal. The theoretical basis for the method is that an externally applied load is shared between the fixator and the regenerating bone. The amount of load carried by the regenerate depends on its axial stiffness, which increases with advanced mineralization. By measuring the force in the fixator while applying a known external load to the limb, the load-share ratio between fixator and limb can be assessed. A load-share ratio of 100% indicates that the entire load is carried by the fixator. The ratio decreases as the regenerate structure gradually stiffens. In a clinical trial of 22 individuals with tibial lengthening, the fixator was removed when the load-share ratio dropped below 10%. None of the patients experienced fracture after removal of the fixator.

Biomechanical Phenomena↗
PubMed2004

The "FAD" (Floating Alveolar Device): a bidirectional distraction system for distraction osteogenesis of the alveolar process.

PURPOSE: The following study illustrates preoperative and perioperative vector management in alveolar distraction using a new distraction system--the "Floating Alveolar Device" (FAD). The FAD is a bidirectional alveolar distractor that allows augmentation of an atrophic alveolar process in several planes, assures easy intraoperative positioning of the planned vector of distraction, and provides correction of the horizontal position of the transported segment during and after vertical distraction. PATIENTS AND METHODS: The FAD is composed entirely of stainless steel and has the following basic components: an upper member, a distraction rod, a lower base plate supporting the vertical force of the distraction rod, a jointed hinge that connects the upper and the lower members, and a tightening rod that provides blocking of the hinge. The clinician can manipulate and adjust the tightening rods, allowing a change in the angle of the hinge, thereby altering the transverse dimension of the vector of distraction. A total of 4 patients aged to 19 to 40 years underwent bidirectional alveolar distraction. All procedures were performed in the mandible. RESULTS: In all treated patients, planned distraction height and direction were achieved. In all cases it was possible to place implants at the planned time. CONCLUSIONS: The most common complication, axial displacement, is easily eliminated by moving the bone with the "floating" rod of the FAD during or immediately after the distraction period, according to the principles of the floating bone concept.

Adult↗
PubMed2005

Quantification of the microstructural anisotropy of distraction osteogenesis in the rabbit tibia.

A longitudinal orientation of fibers and trabeculae has been observed histologically within distracted callus. This study quantified the intensity and angle of orientation of trabeculae within a distracted callus. Sixteen New Zealand white rabbits underwent unilateral tibial callus distraction with an external fixator across a mid-diaphyseal osteotomy. Included were: a seven-day postoperative latency period, ten days of distraction at 0.5 mm every 12 hours, and 20 days of post-distraction consolidation before euthanasia. Tibiae were removed, stripped of soft tissue, sectioned, and processed for decalcified histology. Micrographs of mid-coronal sections of the callus were evenly divided into 12 regions and underwent Fast Fourier Transform (FFT) analysis of the digitized image to determine the angle and intensity of the orientation of the bony trabeculae within the callus. The microstructure of the regenerate callus demonstrated an angle of orientation that uniformly matched that of cortical bone in all of regions of the callus and an intensity of orientation which approached that of cortical bone.

Animals↗
PubMed2002

Characterization of midface maxillary membranous bone formation during distraction osteogenesis.

The purpose of the study was to follow the early events in bone formation and neovascularization during maxillary distraction and after the consolidation period and to define the characterization of the new bone in the distracted area. Maxillary osteotomy was performed in seven sheep. In five animals, an external distraction device was used for maxillary lengthening of 20 mm at a rate of 1 mm/day for 20 days. Another two animals served as controls without distraction. Sequential biopsies were performed. The methods used for analysis were histologic, immunohistochemical, and ultrastructural by transmission electron microscopy. During the 5 days of latency, a fibrin clot was formed that after 5 days of distraction was replaced by granulation tissue, proliferating mesenchyme-like cells, and capillaries. After 10 days of distraction, the regenerated tissue could be divided into three main zones and two transitional areas: a central zone occupied by many polygonal mesenchyme-like cells and spindle-shaped cells that proliferated intensively; two paracentral zones on both sides of the central zone in which many cells showed morphologic signs of apoptosis leading to a decreased number of fibroblast-like cells embedded in wavy collagen fibers; a transitional area from the central to the paracentral zone in which concentric cellular colonies were believed to represent a novel form of vasculogenesis; distal-proximal zones, located on both sides of the paracentral zones and in continuation with the old bone, showed delicate new woven bone trabeculae that grew continuously in the direction of lengthening and gradually became mineralized; and a transitional area from the paracentral to the distal-proximal zones in which there was recruitment of preosteoblasts from the distracted tissue to the trabecular tips. These further differentiated into osteoblasts that contributed to the trabecular growth. The histologic feature pattern was similar after 15 and 20 days of continuous distraction. At the end of lengthening, after 20 days, delicate longitudinally oriented trabeculae continued to grow by recruiting preosteogenic cells from the central distracted tissue, became mineralized, and were rimmed by osteoblasts. After 6 weeks of retention, the trabeculae thickened and consisted of a mixture of lamellar and woven bone. In conclusion, the distraction force creates a pool of undifferentiated mesenchyme-like cells with osteogenic potential and triggers capillary formation, a clear zonation can be observed during active lengthening, and new bone trabeculae begin to form between 5 and 10 days after distraction, soon become aligned with osteoblasts, and continue to grow as long as distraction force is applied. This characterization may help in any exogenous involvement with growth factors to improve bone quality.

Animals↗
PubMed2003

The effects of osteoporosis on distraction osteogenesis: an experimental study in an ovariectomised rabbit model.

The effects of oestrogen deficiency-associated osteoporosis on callus distraction were investigated in rabbits. Twenty-four female New Zealand rabbits 5 to 6 months old were used. Ovariectomy was performed on 12 rabbits, which composed the osteoporotic model group. Six weeks later, osteotomy was carried out and Ilizarov external fixators were applied to the right proximal tibial metaphyses in both the osteoporotic model group and the control group. Beginning one week postosteotomy, the metaphyses were distracted 0.35 mm twice daily for 3 weeks, and the average length increase obtained for both groups was 17.2 mm (minimum: 16.8, maximum: 19 mm). Following a postdistraction waiting period of 6 weeks for newbone formation, the subjects were sacrified and specimens were examined histopathologically. Radiography was carried out at one-week intervals during the distraction period and at 2-week intervals during the waiting period, and scintigraphy was performed at the end of each period. On histopathologic examination, a significant difference in callus remodeling was observed between the control and osteoporotic model groups. On radiologic evaluation it was observed that, while both groups had inadequate callus tissue at the end of the waiting period, callus formation and remodeling occurred later in the model group than in the control group, and the new bone was more osteoporotic. Osteoporosis associated with estrogen deficiency adversely affects the outcome of callus distraction. Nonetheless, radiographic findings in rabbits indicate that the effects may not be so great as to preclude clinical procedures. It was concluded that these results should be supported with clinical studies.

Animals↗
PubMed2001

Tissue differentiation and cytokine synthesis during strain-related bone formation in distraction osteogenesis.

To investigate the contributions of various cytokines that are involved in mechanically related bone formation, we applied defined uniaxial strains in a rabbit model of mandibular elongation and examined the regenerating bone during early stages of dist raction osteogenesis by histomorphometry. We also measured serum concentrations of various cytokines during the distraction. Cell proliferation and differentiation indices correlated significantly (P<0.001) with the extent of load application. Serum concentrations of insulin-like growth factor-1 (IGF-1) decreased after osteotomy whereas transforming growth factor beta1 (TGFbeta1) showed a postoperative increase. Prostaglandin E2 (PGE2) concentrations were constant throughout the experimental period. Collagen degradation decreased slightly postoperatively and increased in samples exposed to higher magnitudes of strain. Our data show that it is the magnitude of mechanical strain that decides tissue response by a characteristic cell proliferation and differentiation. The operative trauma leads to inverse changes in serum concentrations of TGFbeta1 and IGF-1, thereby promoting the recruitment of osteoblastic precursor cells as well as collagen matrix synthesis.

Animals↗
PubMed2001

Vector control in lower jaw distraction osteogenesis using an extra-oral multidirectional device.

PURPOSE: This cephalometric study describes structural changes in facial features and occlusion during distraction of the mandible. PATIENTS: Seven patients aged 7-16 years with severely retrognathic lower jaws were treated by bilateral extra-oral distraction. The direction of the distraction was changed during the distraction period (mean 30 days) using the adjustable hinge in the distractor. Cephalometric follow-up documents were analysed for changes in facial and occlusal structures. The distraction therapy proceeded in two phases. First, horizontal distraction was undertaken to achieve a good incisor relationship. After this, the direction was changed to a more vertical plane with the use of a hinge axis, and the tips of the lower incisors were used as the axis of rotation. RESULTS: The most remarkable changes were in the more anterior position of the lower jaw, the increase in ramus height and good dental overjet. The mandibular occlusal plane became more horizontal, creating a posterior open bite. By guiding the vector of distraction, no anterior open bite or lateral crossbite appeared. CONCLUSION: This study points out the advantages of using extra-oral multidimensional distractors. Severe lower jaw deficiency requires not only a long working length of the device but also precise control of the vector during the active phase of distraction.

Adolescent↗
PubMed1999

Intraoral widening and lengthening of the mandible in baboons by distraction osteogenesis.

PURPOSE: The purpose of this study was to analyze the skeletal and dental positional changes and histomorphology of the distraction regenerates and mucogingival periosteal tissues that occurred after simultaneous widening and bilateral lengthening of the mandible in baboons by a miniaturized intraoral bone-borne distraction appliance. MATERIALS AND METHODS: Distraction appliances were activated 5 days after vertical ramus and symphyseal osteotomies at a rate of 0.9 mm/d for 10 days. The appliances were then stabilized for 8 weeks, after which the animals were killed. The distraction gaps and gingival tissues were analyzed clinically, histologically, and by standardized radiographic studies. RESULTS: Positional changes of the canines and incisor apices were proportional to the skeletal movements. Tipping of both incisors toward the center of the distraction gap was observed. Proportionate movement of the superior and inferior portion of the distracted segments was noted. Newly formed longitudinal trabecular columns parallel to the vector of distraction originated from the intact margins of alveolar bone contiguous with the adjacent teeth. Active histogenesis occurred in the stretched mucogingival periosteal tissues located in the distraction gaps. CONCLUSIONS: The results of this investigation support the clinical use of the miniaturized intraoral bone-borne distraction appliance to selectively widen and lengthen the mandible. The orientation of the mandibular distractors must be parallel to the common vector of distraction, which should be parallel to the maxillary occlusal plane. The formation of a bone regenerate in the alveolar region depends on the presence of an adequate bone interface on either side of the distraction gap.

Alveolar Process↗
PubMed2002

Cubitus varus--correction by distraction osteogenesis.

Cubitus varus deformity in thirty children was corrected by gradual medial opening wedge osteotomy. The osteotomy was stabilized and distracted by simple external fixator-cum-distractor. The patients of both sexes and age from 6 to 14 years, had varus deformity from 17 degrees to 43 degrees. We achieved good to excellent results in 28 cases as regards to correction of deformity and range of motion at elbow joint. None of the cases had neurological deficit or permanent stiffness. One case had fair result due to under-correction and another case had a poor result as osteotomy united before correction. The main complication faced was superficial pin-site infection particularly in summer season and a in fatty children but was managed by good pinsite dressing and care. The technique has been found to be quite effective, technically simple, cosmetically acceptable and with little, if any, lazy S deformity.

Adolescent↗
PubMedDate not supplied

Horizontal alveolar ridge distraction osteogenesis in dogs: radiographic and histologic studies.

PURPOSE: This study was designed to evaluate the healing process in horizontal alveolar ridge distraction of the narrow alveolus in dogs. MATERIALS AND METHODS: Six beagle dogs weighing approximately 9 to 10 kg were used in this experiment. Horizontal alveolar ridge distraction was performed in the right mandible, where the premolars had been extracted 12 weeks previously. Twelve days after the completion of distraction, the lengthening apparatus was removed. The distracted site was evaluated at 12 and 24 weeks after the removal. RESULTS: At 12 weeks, thin woven bone was observed at the distracted site growing from the surface of the original lingual cortical bone toward the transport segment. At 24 weeks, the distracted site had fully changed into new mature lamellar bone, but the transport segments had been almost completely resorbed. DISCUSSION: Horizontal alveolar ridge distraction was performed successfully in beagle dogs even though the apparatus was removed 12 days after the completion of distraction. The most important feature of this technique is the resorption of the transport segment. CONCLUSION: Horizontal alveolar ridge distraction can be a beneficial technique for augmenting the alveolar ridge horizontally in the buccolingually reduced alveolar process before the placement of implants.

Alveolar Process↗