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Correction of upper airway obstruction in the newborn with internal mandibular distraction osteogenesis.

Tracheostomy for management of neonatal airway obstruction may be life saving but is associated with complications and developmental problems. As an alternative, the effectiveness of internal mandibular distraction osteogenesis was investigated in select neonatal patients with micrognathia and upper airway obstruction. Preoperative tests (sleep study, direct laryngobronchoscopy, and "milk scan" for GI reflux) were used to select appropriate candidates for the procedure. Excluded were patients with 1) central apnea, 2) severe reflux, 3) other airway lesions, and 4) mild to moderate obstruction controlled by positioning. Of 44 newborns (aged <3 weeks) with upper airway obstruction and micrognathia seen in the neonatal intensive care unit, 19 underwent tracheostomy, 10 were discharged with home monitoring and positional instructions, and 15 underwent bilateral mandibular lengthening with microdistractors. Of those who underwent mandibular distraction, a tracheostomy was avoided in 14 of 15 patients. Relative improvement in the posterior airway space was seen on 3D CT scans, cephalograms, and laryngobronchoscopies obtained preoperatively, postoperatively, and during follow-up evaluation. One of these 15 patients required a tracheostomy for postoperative central apnea. In an average of just 4.5 days following completion of distraction, patients were discharged home with improved oral feeding and no feeding tube. This study suggests that for selected newborns, the use of internal microdistractors allows for avoidance of a tracheostomy and improved oral feeding.

Airway Obstruction↗

Development of tensile strength during distraction osteogenesis in a rat model.

These studies were designed to determine the reliability of in vitro tensile testing to measure the temporal development of regenerate bone strength in rats during limb lengthening (distraction osteogenesis, DO). External fixators were placed on the right tibiae of 36 virus-free, 400-450 g male Sprague Dawley rats, and osteotomies (n = 33) were performed. Distraction was initiated the following morning (0 day latency) at 0.4 mm/day and continued to day 20. The 8 mm gap was allowed to consolidate for up to 50 days (day 70 postop). Contralateral unoperated and operated (fixator only) controls were included. On days 20, 30, 50 and 70 postop, the rats were anesthetized, and their tibiae were radiographed prior to undergoing sacrifice for histological or tensile analysis. On day 70, an additional group was tested by three-point bending. Radiodensity measurements demonstrated progressive mineralization of the DO gap, and histology confirmed typical intramembranous ossification of collagen bundles oriented parallel to the distraction force. Tensile stiffness increased significantly between days 20 and 30 postop, this increase correlated with initial radiographic and histologic bridging of the DO gap. Energy to failure and ultimate tensile strength increased progressively to day 70. At day 70, the force to failure for three-point bending was 65% of control tibiae. In conclusion, in vitro tensile testing provides a reliable method to test the development of structural integrity during the early stages of DO. Therefore, the biomechanical effects of postulated modulators of bone repair can be measured during early stages (bone formation, bridging, early consolidation) of DO in a rat model.

Animals↗

[Effect of distraction osteogenesis on circadian rhythm of proliferation index of mandibular osteoblast in goat].

OBJECTIVE: The study was to investigate the circadian rhythm of the proliferation index (PI) of the mandibular osteoblast after distraction osteogenesis (DO) by a comparative study to explain the different rhythm characteristics. METHODS: Forty-eight healthy goats were employed and divided randomly into DO group and control. Four weeks after the right side mandible of DO group was distracted, animals of the both groups were killed at 0:00, 4:00, 8:00, 12:00, 16:00, 20:00 time point subsequently. Samples of 2 cm x 2 cm x 0.5 cm bone tissue were excised from distracted zone of DO group and the right mental foramen zone of the control. Primary cell culture method was employed to isolate the osteoblast from bone tissue and a flow cytometric analysis was used to detect the PI of osteoblast. The data was analyzed with cosinor rhythmometry method and the different rhythm between the two groups were investigated. RESULTS: The PI in the two groups demonstrated cosinor waves. The mesor and amplitude in DO group were significant higher compared with the control(P < 0.05), but there was no significant difference for the acrophase between the two groups (P > 0.05). CONCLUSION: The PI of osteoblast after DO showed significant circadian rhythm. It is suggested that DO is helpful to promote osteoblast proliferation and bone regeneration.

Animals↗

Distraction osteogenesis in the mandible with a motor-driven plate: a preliminary animal study.

Distraction osteogenesis is an established method for lengthening of the mandible and for reconstruction of bony defects. We report on our first experience with a motor-driven 2.7 mm plate which was fixed at the lingual surface of the body of the mandible in Göttingen minipigs following osteotomy of the mandible. The power supply and the timer module were inserted subcutaneously in a neck pocket. A maximum distraction of 13 mm was observed. Further research is necessary before clinical application of a comparable system.

Animals↗

Bone regeneration during distraction osteogenesis: mechano-regulation by shear strain and fluid velocity.

Corroboration of mechano-regulation algorithms is difficult, partly because repeatable experimental outcomes under a controlled mechanical environment are necessary, but rarely available. In distraction osteogenesis (DO), a controlled displacement is used to regenerate large volumes of new bone, with predictable and reproducible outcomes, allowing to computationally study the potential mechanisms that stimulate bone formation. We hypothesized that mechano-regulation by octahedral shear strain and fluid velocity can predict the spatial and temporal tissue distributions seen during experimental DO. Variations in predicted tissue distributions due to alterations in distraction rate and frequency could then also be studied. An in vivo ovine tibia experiment evaluating bone-segment transport (distraction, 1 mm/day) over an intramedullary nail was used for comparison. A 2D axisymmetric finite element model, with a geometry originating from the experimental data, was created and included into a previously developed model of tissue differentiation. Cells migrated and proliferated into the callus, differentiating into fibroblasts, chondrocytes or osteoblasts, dependent on the biophysical stimuli. Matrix production was modelled with an osmotic swelling model to allow tissues to grow at individual rates. The temporal and spatial tissue distributions predicted by the computational model agreed well with those seen experimentally. In addition, it was observed that decreased distraction rate (0.5 mm/d vs. 0.25 mm/d) increased the overall time needed for complete bone regeneration, whereas increased distraction frequency (0.5 mm/12 h vs. 0.25 mm/6 h) stimulated faster bone regeneration, as found in experimental findings by others. Thus, the algorithm regulated by octahedral shear strain and fluid velocity was able to predict the bone regeneration patterns dependent on distraction rate and frequency during DO.

Animals↗

Distraction osteogenesis to treat premature distal radial growth plate closure in a dog.

A 4-month-old Labrador was presented for forelimb lameness and elbow pain. Radiography revealed asymmetric premature closure of the distal radial physis resulting in humeroradial and humero-ulnar subluxation. A four-ring circular external fixator applied to the antebrachium was used to perform distraction osteogenesis. After a 4 day latency period, varying rates of linear distraction were used to lengthen the radius by 50% of its original length, which is significantly longer than has been previously reported. By 69 days after performing the radial osteotomy, the distraction callus had achieved clinical union and the fixator was removed. One year postoperatively, mild lameness was present after exercise and minimal elbow osteo-arthritis was evident radiographically. Complications observed included pin tract drainage, transient carpal contracture and radio-ulnar synostosis.

Animals↗

Rapid orthopedic lengthening of the mandible in primates by sagittal split osteotomy and distraction osteogenesis: a pilot study.

This study proposes the development of an intraoral surgical approach to distraction osteogenesis to treat maxillofacial defects. Bilateral sagittal split osteotomies were made in the ascending ramus and body of the mandible of two adult cynomologus primates, and the dento-osseous segment was completely mobilized. A distraction device was fabricated from a Glen-Ross screw soldered between two mini bone plates. The bone plates were fixed by self-tapping screws to both right and left proximal and distal mandibular segments. Beginning 1 week postoperatively, both distraction plates were opened 1 mm every day until the mandible was advanced a total of 10 mm. Comparison of cephalometric radiographs and study casts prepared preoperatively, at the completion of the mandibular orthopedic advancement, and up to 12 weeks postdistraction, showed that mandibular advancement was successful and stable. There was radiographic evidence of bone filling the osteotomy sites, and there was no scar tissue formation or evidence of relapse.

Animals↗

Patients' responses to distraction osteogenesis: a multi-centre study.

This investigation aimed to compare and contrast practical difficulties experienced by 54 children from three different centres (Mexico City, New York, Paris) treated with either extra-oral or intra-oral distraction devices. The possible effect of distraction osteogenesis on pain/sleeping difficulty, speech and eating problems and disturbance of recreational activities and alteration in sensation were investigated. It was expected that intra-oral devices would reduce the difficulties associated with the distraction process and their psychological effect on the child. Some benefits resulting from the use of intra-oral devices were identified, these included fewer sleeping problems (P = 0.006) and less disturbance of recreational activities (P = 0.002). However, eating and maintaining oral hygiene were more problematic with intra-oral devices the differences between the intra-oral and extra-oral groups was approaching significance at P = 0.07. A major disadvantage of the extra oral device was scarring. In both groups the alteration of lip sensation was temporary, pain was limited to the time of activation of the distraction device. A high level of patients' cooperation was mandatory for successful completion of the treatment.

Adolescent↗

Control of interfragmentary micromotion in Ilizarov distractional osteogenesis.

Growth of the regenerate is affected by various factors during the course of Ilizarov distractional osteogenesis. One of the chief biomechanical factors that influences the quality and rate of bone formation is fixator stiffness. A four-ring Ilizarov apparatus was configured around a synthetic tibia. In a series of trials involving a uniform axial load, different transfixing wire tensions, and the separation of paired proximal and distal rings, fragment displacement was measured. Preliminary results suggest that the effect produced by the distraction of ring pairs on interfragmentary micromotion is as significant as pretensioning of the wires.

Biomechanical Phenomena↗

[Distraction osteogenesis for the repair of cleft palate--an ultrastructural study].

OBJECTIVE: The aim of this study was to explore ultrastructural characters of the newly formed bone in the correction of cleft palate (CP) bone defect by distraction osteogenesis (DO). METHODS: The CP experimental animal models (12 cats) were established surgically, and were divided randomly into the experimental group (10 cats), in which the hard palate bone defects were corrected with DO procedure at the rate of 0.4 mm x 2/day. The specimen retrieval with euthanasia was carried out at 2, 4, 6, 8, 12 weeks after completion of distraction. Ultrastructural study was then performed; the experimental control group (2 cats) was kept for 6 weeks before euthanasia without any correction, the other extra 2 cats were used as the negative control. RESULTS: New bone formation appeared in early 2 weeks. Exclusively intramembranous bone formation was observed in all specimens. The remodeling activities were keep observed throughout the period of study, and the bone structure matured gradually till 12 weeks after the completion of DO. No repair was observed in experimental control group. CONCLUSION: The reconstruction of CP bone defect by means of DO could get active intramembranous bone formation and remodeling, which adapted to normal functional activities.

Animals↗

[Distraction osteogenesis for repair of cleft palate: an experimental study].

OBJECTIVE: To observe the repair of cleft palate (CP) bone defect under the application of distraction osteogenesis (DO); to investigate the correction mechanism in thin bone of palatal shelf and to search a possible new treatment approach for repair of CP. METHODS: 14 cats were assigned randomly to 3 groups: (1) Empty control, 2 cats unoperated with euthanasia at the end of 2 weeks; (2) Experimental control, 2 cats underwent 8 mm x 18 mm palatal osteoectomy in saggital direction as the experimental model of CP with euthanasia in 6 weeks; (3) Experimental group, 10 cats were performed the same palatal osteoectomy as group (2), the newly designed and individual manufactured intraoral distractors were fixed to teeth by brackets and to bilateral palate bone across the defect with titanium miniscrews. 4 weeks later the transport disc (TD) osteotomy were performed and gradual distraction was started after 6 days latency period at the rate of 0.4 mm x 2/day till the TD reached the opposite edge of the CP. Roentgenographic, gross meterage and ultrastructural observation were performed 2, 4, 6, 8, 12 weeks after completion of distraction. RESULTS: All the examinations revealed the TD recombination to the opposite bone edge of the CP, simultaneously, the proportional expansion of overlay mucoperiosteal flap was achieved. The bone defect were filled with de move osteogenesis. Roentgenographically, the new bone mineralization was along the DO vector, developed from the bone cut edges bilaterally to the central translucent zone until turned to thin fissure. Comparison of the plaster casts showed no change in the occlusion or dentomaxillofacial framework. CONCLUSIONS: The intraoral distractor is able to get both effective distraction and steady fixation. The examination results suggest that the CP bone and soft tissue defect could be repaired and acheived functional reconstruction under DO, which could be a new treatment approach for repair of CP.

Animals↗

Maxillary advancement by distraction osteogenesis using osseointegrated implants.

The purpose of this study was to establish a new technique for distraction osteogenesis in the maxilla, using an osseointegrated implant and intraoral device. After extraction of the premolar and molar teeth, four titanium implants were installed in the maxillary alveolar bone. Three months later, the distraction device was connected to the abutments, and osteotomy in the medial portion of maxilla between the implants was performed. Distraction was carried out at the rate of 1 mm per day to obtain a 10-mm elongation, Morphological, radiographic and histological examinations showed that successful maxillary advancement was achieved. New bone was primarily formed by intramembranous ossification and partial endochondral ossification. Titanium implants placed for anchorage of the distraction device remained stable during the course of maxillary advancement. This technique can provide significant advancement of the maxilla with better stability. The treatment system can be applied in any kind of maxillary deformities which need to be corrected surgically by classic osteotomy without bone grafting.

Alveolar Process↗

Distraction osteogenesis using IGF-I after nerve microreconstruction.

The discipline of limb lengthening has undergone numerous advances over the last few years. The neurologic complications surrounding this procedure are well established and described in the clinical setting, and can be deleterious for the patients in distraction osteogenesis protocols. The specific aims of the reported project were: 1) to determine the ability of IGF-I to enhance nerve regeneration in repaired nerves that are subjected to distraction only 4 weeks after nerve repair, and 2) to determine if a low dose of IGF-I applied at the time of the repair is neuroprotective to repaired nerves at this early time window. Forty adult male Sprague-Dawley rats were randomized into eight groups (n=5). Four groups (Groups A to D) underwent distraction of the femoral bone following sciatic nerve repair, and four groups served as controls (Groups E to H). Nerve reconstruction was achieved by end-to-end nerve repair (four groups, two with distraction [A, B] and two without [E, F]) and by interposition nerve grafting (four groups, two with distraction [C, D] and two without distraction [G, H]). A low dose of IGF-I was administered at the time of nerve microreconstruction. Distracted groups, despite the administration of IGF-I, demonstrated no signs of nerve regeneration, as assessed by sciatic functional index (SFI), electrophysiologic studies, and quantitative and qualitative histologic studies. Non-distracted groups showed signs of nerve regeneration. The 4-week time interval between nerve repair and distraction did not provide enough time for nerve regeneration to be completed, even if the repair was exposed to a low dose of IGF-1.

Anastomosis, Surgical↗

Extraoral vs. intraoral distraction osteogenesis in the treatment of hemifacial microsomia.

During hemifacial microsomia (HMF), an important phase of the treatment is elongation of the hypoplastic mandible, mainly the ramus, at an early stage. Twenty-two patients with HFM were treated with distraction osteogenesis: 12 with an extraoral device (10 unidirectional and 2 multidirectional) and 10 with an intraoral device. The mean elongation with the extraoral device was 21 mm, and with the intraoral device was 17 mm, resulting in a more symmetrical facial appearance. The advantages and disadvantages of both methods are presented, based on the authors' experience and a review of the literature. The extraoral device permits elongation of a greater distance, enables extraoral control of the vector of elongation, and conserves the gonial angle by working in many directions. The main disadvantages of the extraoral device are the social inconvenience to the patient and the extraoral cutaneous scars. Conversely, the intraoral device is much more socially convenient to the patient and avoids residual scarring. However, in 2 patients treated with an intraoral device, an undesired contralateral open bite appeared as a result of reduced vector control. The intraoral method should always be considered first because of its previously mentioned advantages. However, in severely hypoplastic patients, when three-dimensional correction and gonial angle control are necessary, or when there is a limited space along the planned distracted bone, the extraoral device has an advantage over the intraoral device.

Adolescent↗

Distraction osteogenesis for lengthening of the hard palate: Part I. A possible new treatment concept for velopharyngeal incompetence. Experimental study in dogs.

Many procedures have been described to correct velopharyngeal incompetence. Significant complications can occur, and the results may not be satisfactory. If the short soft palate has satisfactory muscle function and if it could be moved toward the posterior pharyngeal wall by distraction osteogenesis of the hard palate, an entirely new concept of treatment for velopharyngeal incompetence would be available. The object of the present study was to explore the possibility of osteogenesis occurring in the hard palate in dogs after gradual distraction (callus distraction). Six adult, mix-bred dogs were anesthetized, and the palatal mucosa was elevated. A midpalatal transverse osteotomy and two lateral osteotomies were performed. Tantalum bone markers for cephalometric analysis were placed, and an individually fabricated, orthodontic-like distraction device with an expansion screw in the sagittal direction was inserted. The device was stabilized on the premolars and fixed to the palatal bone with titanium miniscrews. Gradual distraction began after a latency period of 10 to 18 days. The rate of the distraction varied from 0.25 to 0.75 mm per day. The device was left in place for 6 to 8 weeks after expansion to allow for bony consolidation. Assessment was by direct examination, cephalograms, computed tomography, and histology with bone labeling. Impressions of the jaws were taken preoperatively and after device removal to examine plaster cast changes in the dental occlusion. Cephalometric and computed tomographic scan analysis demonstrated a distraction of up to 8 mm. All gaps were filled with de novo osteogenesis. Comparison of the plaster casts revealed no change in the occlusion. At 1 month after distraction, the computed tomographic scan showed the first signs of ossification of the experimental gap from the anterior and posterior bone ends. After 4.5 months ossification was almost complete with a small translucent zone in the middle of the experimental gap. After 7 months ossification was complete.

Animals↗

Distraction osteogenesis of the alveolar ridge: a review of the literature.

One of the principal problems in dental implantation is the lack of sufficient bone height or width. In the case of the alveolar ridge, a very effective technique for resolving this problem is distraction osteogenesis, introduced in this context about a decade ago. This technique is based on the gradual separation of a mobile but fully vascularized bone segment from the basal bone, leading to the formation of an intervening soft callus which gradually transforms to mature bone. A key researcher in the development of this technique was the Russian traumatologist Ilizarov. The present article reviews alveolar ridge distraction procedures and their clinical application. Alveolar ridge distraction may often be preferable to bone grafting or guided bone regeneration for increasing ridge height and width prior to implantation.

Alveolar Process↗

Long-term results of distraction osteogenesis of the maxilla and midface.

Since the beginning of 1998, eight patients have been treated by osteodistraction to correct hypoplasia of the maxilla and midface of various origins. Among them were five patients who were treated by high LeFort I osteotomies and insertion of subcutaneous intraoral distraction devices in the malar region. In the remaining three patients, extraoral distraction devices were applied after LeFort II and III osteotomies. Distraction osteogenesis was successful in all cases, resulting in a mean sagittal bone gain measured parallel to the skull base of 9.0 mm (range 4.5-12.0) in the group treated with intraoral distractors and a mean of 20.3 mm in the extraoral distraction group (range 15.0-25.0). All patients were kept under orthodontic supervision before, during, and after osteodistraction. Long-term cephalometric and clinical evaluation after a mean follow-up period of 24 months in the intraoral distraction group (range 22-26) and 12 months in the extraoral distraction group (range 10-14) show stable results concerning the skeletal and dental relations. Long-term follow-up is necessary.

Adolescent↗