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Fracture after distraction osteogenesis.

We reviewed 173 patients undergoing distraction osteogenesis to determine the incidence, location and timing of fractures occurring as a complication of the procedure. There were 17 fractures in 180 lengthened segments giving an overall rate of fracture of 9.4%. Unexpectedly, the pattern and location of the fractures were very variable; six were within the regenerate itself, six at the junction between the regenerate and the original bone and five at distant sites in the limb. Of those occurring in the regenerate, five were noted to be associated with compression and partial collapse of the regenerate. In three patients collapse and deformity developed gradually in the distracted segment over the six months after removal of the frame. The method of treatment of these fractures should be chosen to take into account multiple factors, which are additional and often different from those to be considered during management of acute traumatic injuries. Internal fixation appears to be most appropriate for displaced fractures, although in small children, or in those in whom there has been, or is, infection of the screw tracks, a new period of treatment using external fixation may be needed. Fixation by intramedullary nailing was associated with a risk of infection, even if screw tracks were assessed as healthy at the time of insertion of the nail. Internal fixation with the use of plates is safe for displaced, unstable fractures in children.

Adult↗

Systemic regulation of distraction osteogenesis: a cascade of biochemical factors.

This study investigates the systemic biochemical regulation of fracture healing in distraction osteogenesis compared with rigid osteotomy in a prospective in vivo study in humans. To further clarify the influence of mechanical strain on the regulation of bone formation, bone growth factors (insulin-like growth factor [IGF] I, IGF binding protein [IGFBP] 3, transforming growth factor [TGF] beta1, and basic FGF [bFGF]), bone matrix degrading enzymes (matrix-metalloproteinases [MMPs] 1, 2, and 3), human growth hormone (hGH), and bone formation markers (ALP, bone-specific ALP [BAP], and osteocalcin [OC]) have been analyzed in serum samples from 10 patients in each group pre- and postoperatively. In the distraction group, a significant postoperative increase in MMP-1, bFGF, ALP, and BAP could be observed during the lengthening and the consolidation period when compared with the baseline levels. Osteotomy fracture healing without the traction stimulus failed to induce a corresponding increase in these factors. In addition, comparison of both groups revealed a significantly higher increase in TGF-beta1, IGF-I, IGFBP-3, and hGH in the lengthening group during the distraction period, indicating key regulatory functions in mechanotransduction. The time courses of changes in MMP-1, bone growth factors (TGF-beta1 and bFGF), and hGH, respectively, correlated significantly during the lengthening phase, indicating common regulatory pathways for these factors in distraction osteogenesis. Significant correlation between the osteoblastic marker BAP, TGF-beta1, and bFGF suggests strain-activated osteoblastic cells as a major source of systemically increased bone growth factors during callus distraction. The systemic increase in bFGF and MMP-1 might reflect an increased local stimulation of angiogenesis during distraction osteogenesis.

Adult↗

Treatment of craniosynostosis by distraction osteogenesis.

PURPOSE: Craniosynostosis patients treated with one-stage cranioplasty often have bleeding from the dura mater, fluid collection in the extradural space, and poor wound healing due to skin overstretching. To avoid these complications, we began using distraction osteogenesis. To determine the advantages and disadvantages of the procedure, we retrospectively compared distraction osteogenesis with conventional cranioplasty. PATIENTS AND RESULTS: We treated 24 patients with fronto-orbital advancement. Fifteen had one-stage cranioplasty; 9 received distraction osteogenesis. The one-stage operation patients averaged 25.5 months of age at surgery, 289 min of operating time, and 154 ml of intraoperative blood loss. For the distraction group, the average age was 16.6 months, average operating time was 196 min, and average blood loss was 76 ml. CONCLUSIONS: Compared with one-stage cranioplasty patients, distraction osteogenesis patients had significantly less intraoperative bleeding and shorter operating times. The disadvantages of distraction treatment were the need for multiple surgeries, prolonged hospitalization, wound infection, and dislocation of the distraction device.

Blood Loss, Surgical↗

Distraction osteogenesis after irradiation in a rabbit model.

BACKGROUND: The present study was performed to investigate the effects of preoperative irradiation on distraction osteogenesis, as little is known about how preoperative irradiation delays distraction osteogenesis. METHODS: A single dose of irradiation was applied to the right rear legs of rabbits. This was followed by tibial lengthening at a rate of 0.5 mm/day, which was continued for 4 weeks. Bone regeneration was examined radiographically and histologically. RESULTS: In the irradiation group, the radiographs showed little regeneration during the elongation phase. During the maturation phase, the callus appeared slowly, and its formation was spotty. Furthermore, regeneration was not completed until the fourth week of the maturation period. Histological examination at the end of distraction showed a gap in the distraction consisting of loose connective tissue, with part of the fibrous tissue oriented longitudinally. Four weeks after completion of distraction, the major part of the radiolucent region consisted of cartilage. The spotty osteogenesis was identified as enchondral ossification. Immunohistochemical examination of the regeneration area revealed that the blood vessels were extremely localized, and that the level of expression of vascular endothelial growth factor (VEGF) in the osteoblasts was high. Microangiography showed that vascularization at the distracted sites was poor. Distraction osteogenesis was decreased markedly by preoperative irradiation in terms of both rate and process. The results suggested that most of the osteoprogenitor cells were damaged immediately after irradiation. The high level of VEGF in the osteoblasts and the enchondral ossification also suggested a hypoxic state in the distracted region. CONCLUSIONS: Preoperative irradiation interferes with distraction osteogenesis by inducing a state of poor angiogenesis.

Angiography↗

Acceleration of regenerate ossification during distraction osteogenesis with recombinant human bone morphogenetic protein-7.

BACKGROUND: Bone-lengthening can be accomplished by means of distraction osteogenesis. In the present study, we examined the effect of a single dose of recombinant human bone morphogenetic protein-7 (rhBMP-7) on the rate of new-bone formation during distraction osteogenesis in the rat. METHODS: Fourteen Long-Evans rats were randomized into two groups of seven rats each. An external fixator was applied to the left femur, and a transverse osteotomy was performed. One group was treated with rhBMP-7 in an aqueous solvent, and the other group received the solvent alone and served as the control. rhBMP-7 was administered on the day of surgery by means of a single injection into the osteotomy gap. Distraction was started seven days after surgery at a rate of 0.25 mm every twelve hours. Distraction was continued for twenty days, resulting in a total of 10 mm of lengthening. The regenerate was monitored with use of radiographs and bone-mineral-density measurements at the conclusion of distraction and at two and four weeks after the cessation of distraction. The lengthened femora were harvested, and biomechanical studies were carried out to determine the stiffness and maximum torque to failure. RESULTS: Radiographs showed accelerated regenerate ossification in the BMP-7 group, with a larger amount of new bone compared with the control group. The bone-mineral-density values were dramatically enhanced on Day 20 in the BMP-7 group (103.6 +/- 12.6 mg/cm (2) ) compared with the control group (26.2 +/- 15.1 mg/cm (2) ). These differences continued to be greater at two and four weeks after the cessation of distraction. Normalized values of stiffness (percent stiffness) reached 76.5% +/- 5.4% in the BMP-7 group, compared with 6.6% +/- 0.5% in the control group. The percent maximum torque at failure was 81.1% +/- 1.2% in the BMP-7 group, compared with 20.8% +/- 0.3% in the control group. CONCLUSION: A single injection of rhBMP-7 at the time of osteotomy surgery stimulated the rate of regenerate ossification and increased bone-mineral density during distraction osteogenesis. The biomechanical properties of the newly formed bone were also increased by BMP-7 injection.

Animals↗

[Orthognathic surgery and distraction osteogenesis for treatment of obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To discuss the indication and protocol of surgical therapy when treating mandibular micrognathism accompanying obstructive sleep apnea-hypopnea syndrome (OSAHS) using distraction osteogenesis and orthognathic surgery. METHODS: A total of 17 patients with mandibular micrognathism accompanying moderate to severe OSAHS, aged 11 to 59 years, 15 men and 2 women, were reviewed. Four of them were treated with orthognathic surgery, 5 of them were treated with distraction osteogenesis, and the other 8 patients were treated with an integrated procedure combining distraction osteogenesis with orthognathic surgery. Cephalometric analysis and polysomnography studies were obtained pre- and postoperatively. RESULTS: SNB angle changed from 64.6 degrees to 71.9 degrees, post airway space (PAS) from 5.4mm to 13.2 mm, apnea and hypopnea index (AHI) from 58.4 to 7.6, lowest saturation of oxygen (LSAT) from 66% to 87%. All the differences showed statistical significance (P < 0.001). The average mental horizontal advancement (MHA) was 14.3 mm and its correlation coefficients with deltaSNB, deltaPAS, deltaAHI, and deltaLSAT were 0.36, 0.62, 0.34, and -0.14, respectively. CONCLUSIONS: Both distraction osteogenesis and orthognathic surgery can be effectively used to treat patients with mandibular micrognathism accompanying OSAHS with slightly different indications. A combination of these two operations may be preferred.

Adolescent↗

[A histological study of three-dimensional external zygomatic suture distraction osteogenesis].

OBJECTIVE: To explore the histological change in suture of zygomatic bone for the zygomatic suture direct distraction osteogenesis. METHODS: The zygomatic bone was distracted by 3-D external distraction appliance without osteotomy. The specimens were taken 1, 3, 5 and 8 weeks after, and then examined histologically and compared with the blank contralateral side. RESULTS: There were lots of fibroblasts, osteoblasts and capillary vessels in the distracted suture tissues one week after distraction, and the fibers were observed to connect the sides of suture and arranged orderly. The surfaces of the expanded suture were irregular. Bone formation was active in the expanded side. The bone trabeculae were mature and oriented in the direction of distraction in the distracted sides at 3 weeks. A great amount of new woven bones were found in 5-week specimen. New bones were formed completely 8 weeks after the distraction. CONCLUSIONS: New bone formed rapidly in the distracted side of zygomatic bone under suture distraction osteogenesis without osteotomy.

Animals↗

[A histomorphologic and enzyme histochemical study of masticatory muscles affected by distraction osteogenesis of mandible].

OBJECTIVE: The purpose of this study was to study the masticatory muscles affected by distraction osteogenesis of the mandible. METHODS: The distraction osteogenesis (DO) was applied to distract the left mandible of 6 mongrel dogs that were divided into three experimental groups. After different distraction phase and consolidation phase, the masseter and the digastric muscle were taken out. The specimens were stained using hematoxylin/eosin and enzyme histochemistry. Afterwards, the specimens were observed with a light microscope to study the morphologic changes of the muscles. The contents of enzyme in the different groups were measured by VIDAS. RESULTS: The masseter showed consequently atrophy, but the digastric muscle showed a progress of histomorphologic reconstruction, including atrophy and hypertrophy. The changes of the contents of enzyme and histomorphology were identical in the masticatory muscles. CONCLUSION: The digastric muscle parallel to the vector of mandibular distraction adapts the distraction by the way of atrophy, regeneration and hypertrophy. And the contents of enzyme appear to decrease at the beginning, increase afterwards, and return to the normal level finally. But the masseter perpendicular to the vector of mandibular distraction shows consequent atrophy, and the contents of enzyme consequently decrease, which means the metabolism decrease.

Adenosine Triphosphatases↗

[The establishment of an animal model of bilateral mandibular distraction osteogenesis in rabbits].

PURPOSE: To establish an animal model of bilateral mandibular distraction osteogenesis in rabbits. METHODS: 16 adult male white New Zealand rabbits were divided into 4 groups randomly, 4 in each group. Osteotomy was performed on mandible bilaterally before the first premolar. Bone stumps were repositioned and fixed with distractors. After 7 days of latency period, distraction was initiated at a rate of 1mm/d for 7 days. Then distractors were held in place for days. Animals were killed at different time points, and specimens were taken for X-ray and histology examination. RESULTS: The mandibles were lengthened successfully. The distraction gaps were filled with regenerated bone tissue. CONCLUSION: The method in this study is practicable and repeatable which could be used to establish an animal model of mandibular distraction osteogenesis in rabbits.

Animals↗

[Application of low intensity, pulsed ultrasound on distraction osteogenesis of the humerus. Case report].

Low intensity pulsed ultrasound accelerates fracture healing both clinically and experimentally. Based on recently published animal studies, an improvement in regenerative bone maturation after distraction osteogenesis due to low intensity, pulsed ultrasound is also expected. We report on an 18 year-old female patient suffering from an acquired shortening of the right upper arm of 10 cm after humeral osteitis as a baby. The patient was admitted to hospital for corticotomy and distraction osteogenesis at the afflicted humerus. Due to the published experimental results in animals which indicate an improvement in bone regeneration during callotasis with the additional application of low intensity, pulsed ultrasound, we decided to try this procedure. The calculated distraction consolidation index was 21 days/cm, which is below the mean of 30 days/cm reported in the literature for humeral lengthening by distraction osteogenesis. The calculated healing index according to Paley was 0.7 months/cm in our patient. Compared to reference data, in which a range of from 0.87 months/cm to 1.5 months/cm is reported, our patient showed an accelerated maturation of distraction callus. The duration of treatment of the patient was clearly shortened by the additional application of low intensity, pulsed ultrasound. If distraction osteogenesis is correctly indicated, the early use of low intensity, pulsed ultrasound should be considered, since an acceleration of callus formation with consecutive shortening of treatment time could be attained while wearing an external fixator, leading to a decrease in cumulative complications, such as pin tract infections. Further studies from our research group regarding this topic will follow.

Adult↗

[Application of distraction osteogenesis in correction of hemifacial microsomia].

OBJECTIVE: To study the effect of distraction osteogenesis of mandibular ramus in correcting hemifacial microsomia. METHODS: From December 1997 to March 2000 two kinds of mandibular distractors made in Germany and China were used in 11 cases with hemifacial microsomia aged 4.5 approximately 23 years (on average 14.1 years). Orthodontic treatment was given during the distraction. LeFort I osteotomy and genioplasty were performed in 5 cases and 4 cases respectively. RESULTS: The treated mandibular rami were lengthened 15 approximately 30 mm. No infection and dysosteogenesis was found. In only one case, the distractor failed to function at the third day of treatment and was replaced. The distractor was removed after 3 months while new bone was formed in all cases. All of the patients and their family members expressed their satisfaction with the results of treatment. CONCLUSION: Mandibular distraction osteogenesis is the most effective procedure for correcting hemifacial microsomia.

Adolescent↗

Formation of new bone during vertical distraction osteogenesis of the human mandible is related to the presence of blood vessels.

We examined the effect of distraction rate on blood vessel growth in intramembraneous ossification after vertical distraction osteogenesis in the human mandible. Six edentulous patients (aged 60+/-9 years) with a severely atrophic mandible underwent bone augmentation with distraction osteogenesis. Two distraction rates (0.5 and 1 mm/day) were compared and for each group three patients were analyzed. Vascular histomorphometry was carried out in two different areas in the distraction gap: (1) in the first and (2) in the second 1 mm area from the osteotomy line, representing the oldest and younger new-bone area, respectively. Correlation analysis was performed between blood vessel parameters and the amount of new bone formed during distraction. Histological analysis demonstrated the presence of blood vessels throughout the soft connective tissue in the distraction gap. The volume density of blood vessels between the two investigated areas was significantly lower in the 1 mm/day groups, suggesting a delay in angiogenesis in this group of patients. A positive correlation between blood vessel volume and bone volume density was found in the younger new-bone area but not in the oldest new-bone area. This correlation was due to a higher number of blood vessels rather than to a larger size of the blood vessels. Our data suggest that the lower blood vessel density found in the patients with 1 mm/day distraction rate may be related to disruption of angiogenesis in the soft connective tissue of the gap or to a less optimal mechanical stimulation of cells involved in angiogenesis. This probably results in the slower rate of osteogenesis seen at the 1 mm/day distraction rate compared with the 0.5 mm/day distraction rate. The data support the concept that a positive relationship exists between the density of blood vessels and the formation of bone. For distraction of the human mandible in elderly patients, a distraction rate of 0.5 mm/day seems beneficial.

Age Factors↗

The early psychological adjustment of cleft patients after maxillary distraction osteogenesis and conventional orthognathic surgery: a preliminary study.

PURPOSE: To compare the early psychological changes of cleft lip and palate (CLP) and noncleft patients after maxillofacial corrective surgery, including maxillary distraction osteogenesis and conventional orthognathic surgery. MATERIALS AND METHODS: Nine CLP patients were compared with a group of 9 non-CLP patients having similar dentofacial deformities in a prospective longitudinal cohort study. Five of the CLP patients underwent maxillary distraction osteogenesis and 4 underwent conventional orthognathic surgery. A control group of 9 noncleft patients received conventional orthognathic surgery. All patients completed a set of questionnaires to enable their psychological profile to be assessed. The data were collected immediately before surgery (T1), and at 3 weeks (T2) and 12 weeks (T3) after surgery. RESULTS: The CLP patients treated with distraction osteogenesis were happier, but had a higher level of social anxiety and distress than the CLP patients receiving conventional orthognathic surgery. On the other hand, the CLP patients overall were happier, with lower social anxiety and distress, than the noncleft control group. The CLP patients showed a higher level of parental self-esteem than the noncleft patients. CONCLUSION: This preliminary study shows that CLP patients were generally happier, and had a higher level of parental support, than normal patients suffering from dentofacial deformities. Maxillary distraction osteogenesis seemed to induce a higher level of anxiety and distress in CLP patients than conventional orthognathic surgery in both cleft and noncleft patients.

Adaptation, Psychological↗

Effect of distraction osteogenesis of the mandible on upper airway volume and resistance in children with micrognathia.

Children with craniofacial anomalies often have compromise of the upper airway, a condition with potential for morbidity and mortality. In children with microretrognathia, the diminutive size and retruded position of the mandible reduces the size of the oropharynx, thereby predisposing to glossoptosis and airway obstruction. Although several authors have reported successful use of mandibular distraction osteogenesis to alleviate this type of upper airway obstruction, the physiologic relationship between changes in mandibular shape, size, and position and upper airway dynamics remains undefined. The purpose of this study was to develop methodologies to quantitatively evaluate upper airway dynamics in children with micrognathia both before and after mandibular distraction osteogenesis. The patient population consisted of four children with micrognathia who had successfully undergone upper airway stabilization by bilateral mandibular distraction osteogenesis. The data used were digitally archived computed tomographic scan data from high-resolution, thin-slice head computed tomographic scans obtained before and after mandibular distraction. Upper airway evaluation was performed in two ways: static and dynamic. Static analysis consisted of computer quantification of predistraction and postdistraction mandibular and upper airway volumes using Analyze imaging software. Dynamic analysis consisted of fabrication of rigid stereolithographic hollow cast models of the upper airway produced from computed tomographic scan data. Models were used for characterization of upper airway resistance and flow patterns as related to respiration. After distraction osteogenesis, mandibular total volume increased 32, 32, 18, and 25 percent (mean, 27 percent) and upper airway volume increased by 20, 31, 23, and 71 percent (mean, 37 percent). A significant decrease in flow resistance, both inspiratory and expiratory, was observed in the patient with the greatest upper airway volume increase (71 percent) after distraction. After distraction, the inspiratory resistance was diminished by 51 percent and the expiratory resistance diminished by 85 percent. However, the three patients with more modest upper airway volume increases of 20 to 31 percent demonstrated no statistically significant change in flow resistance after distraction. Results of this study support the conclusion that distraction osteogenesis of the micrognathic mandible increases the volume of the upper airway, roughly paralleling the increase in mandibular volume. In the biomechanical airway model studied, upper airway volume expansion has been shown to be able to decrease the flow resistance over the length of the airway, presumably secondary to an increase in the average cross-sectional area. The artificial rigidity of the stereolithographic "airway" compared with the elasticity of the human upper airway may account for the insensitivity of this model to smaller but clinically significant airway changes.

Airway Resistance↗

Bone response to functioning implants in dog mandibular alveolar ridges augmented with distraction osteogenesis.

The specific aim of this study was to determine the response of alveolar bone after it was augmented vertically using distraction osteogenesis and subsequently loaded with implant restorations. Four dogs each had four implants placed horizontally into an edentulous mandibular quadrant and, after integration, a distraction osteogenesis device was fabricated in the laboratory. An osteotomy was made to allow the crest of the alveolar ridge to be distracted vertically. After 10 mm of vertical distraction, the device was stabilized with light cured resin. Following bone fill confirmation of the distraction gap at 10 weeks, two implants were placed into the ridges, one in distracted bone and one in nondistracted bone. After 4 months for implant integration, freestanding prostheses were fabricated. Crestal bone levels were evaluated throughout the period of function. Animals were sacrificed after 1 year of loading, for histologic evaluation of the bone. The vertical ridge augmentation averaged 8.85 +/- 1.05 mm after 10 weeks of healing following distraction, without change over 1 year of implant loading. Histologic examination showed that bone had formed between the distracted segments, creating an augmented ridge. The average thickness of the labial cortex in the distraction gap was significantly thinner than the lingual cortex in distracted bone and the lingual and labial nondistracted cortical bone. The presence of the dental implant did not significantly affect cortical bone thickness. Serial sections showed that implants remained integrated and functional without soft tissue inflammation. Dental implants placed into alveolar ridges augmented with the technique of distraction osteogenesis maintained bone and were functional for the length of this study.

Alveolar Ridge Augmentation↗

Distraction osteogenesis by Ilizarov and unilateral external fixators in a canine model.

We studied distraction osteogenesis in canine experimental model using two types of external fixators, Ilizarov (n=6) or AO unilateral (n=9) external fixator. Distraction started 1 week after surgery (2 x 0.5 mm/day) and lasted for 3 weeks. Specimens were harvested from weeks 7 through 12. The outcome was assessed by X-ray, histology, histomorphometry and microradiography. Bone regeneration as observed by X-rays was satisfactory and similar in both groups. Both endochondral ossification and intramembranous ossification were found simultaneously in both groups. In both groups, bone formation parameters were significantly higher in the area of consolidating bone. No differences in histomorphometric parameters existed between the groups. In the study period, the bone formation was enhanced and prevailed in the distraction area. This study demonstrated the utility of the canine experimental model for the study of distraction osteogenesis.

Animals↗

Reconstruction of mandibular condyle by transport distraction osteogenesis: Experimental study in rhesus monkey.

PURPOSE: This study investigated histomorphologic changes in the newly formed condyle reconstructed by transport distraction osteogenesis through a nonhuman primate model. MATERIALS AND METHODS: Six adult rhesus monkeys were used in this study. Bilateral condyles and articular discs were extirpated, and the technique of transport distraction osteogenesis was carried out to reconstruct the condyles. X-ray and 3-dimensional (3D) computed tomography (CT) scanning films were taken at various intervals. Two monkeys were killed respectively at 4, 12, and 24 weeks after completion of distraction; the transport segments and the distracted calluses were harvested and processed for histologic examination. The original condyles removed at surgery served as normal control. RESULTS: Open bite was seen in all animals postoperatively and diminished at the end of distraction. Bone regeneration was perfect in the distraction gap between the transport disc and the pre-existing mandible. The bony transport disc gradually remodeled to a neocondyle that was similar to the original condyle in the appearances and structures. The head of neocondyle was covered with a fibrous cap, which might play the role of an articular disc. CONCLUSION: A neocondyle with functional shape can be created by transport distraction osteogenesis. This suggests that this technique is an alternative method for reconstruction of the mandibular condyle.

Animals↗

Effect of recombinant human bone morphogenetic protein-2 on mandibular distraction osteogenesis.

The purpose of this investigation was to study the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) on bone formation of mandibular distraction osteogenesis. Six skeletally mature sheep underwent 10 mm of bilateral mandibular distraction osteogenesis via a custom-made distractor. Three micrograms of rhBMP-2 with a collagen carrier was implanted in the osteotomy site of one side of the mandible during the osteotomy phase. The contralateral side was used as the control group, and no material was implanted into the distracted area. At 10 days after the end of distraction, all animals were killed, and the distracted calluses were harvested for radiologic and histologic analysis. New bone was generated in the distracted zone in all groups. Histologic and radiologic examination showed that the new bone formation was greater in the rhBMP-2 group than in the control group. Quantitative computed tomography evaluation, however, did not demonstrate a significantly different mean bone density of the regenerates between the 2 groups. The results indicate that application of a rhBMP-2/collagen implant during the osteotomy phase of distraction osteogenesis increased bone formation but did not have a significant effect on bone density of the regenerates.

Animals↗