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Proliferation of masseter myocytes after distraction osteogenesis of the porcine mandible.

PURPOSE: Long-term success of distraction osteogenesis depends on the ability of the surrounding soft tissues to tolerate distraction forces and to adapt to the resulting increase in skeletal length and volume. The hypothesis tested in this study was that mandibular elongation by distraction induces myocyte proliferation. MATERIALS AND METHODS: Unilateral mandibular angle osteotomies were performed in 16 Yucatan minipigs. The hemimandibles were lengthened using semiburied distraction devices (Synthes Maxillofacial, Paoli, PA) with 0-day latency, 1, 2, or 4 mm/d distraction rates, and a neutral fixation period of twice the gap size in days. In 2 additional animals, the dissection and osteotomies were performed, and distraction devices were placed without activation (sham control). At the end of neutral fixation, tissues were taken from masseter muscle overlying the osteotomy and the equivalent region on the unoperated side (contralateral control). Proliferation of myocytes was estimated using immunohistochemical localization with antibodies against proliferating cell nuclear antigen (PCNA). RESULTS: Muscle overlying the distracted mandible showed 6-fold more PCNA-positive myocytes (16.8% +/- 11.3%) than the contralateral control side (2.8% +/- 1.1%, P < .0001). In the 2 sham-control animals, there was a low index of PCNA-positive myocytes on both the osteotomy (2%, 5%) and the contralateral sides (1%, 2%). CONCLUSIONS: The results of this study suggest that distraction of the porcine mandible by the protocol described induces myocyte proliferation in the masseter muscle. A proliferative response may contribute to improved long-term stability of mandibular expansion by distraction osteogenesis.

Animals↗

Distraction osteogenesis of costochondral bone grafts in the mandible.

Costochondral grafting for reconstruction of the Pruzansky type III mandible has given variable results. Lengthening of the rib graft by means of distraction had been advocated when subsequent growth of the grafted mandible is inadequate. This retrospective study reviews a series of patients with mandibular costochondral grafts who underwent subsequent distraction osteogenesis of the graft. A retrospective review identified two patient groups: group 1 consisted of individuals (n = 9) who underwent costochondral rib grafting of the mandible followed by distraction osteogenesis several months later at a rate of 1 mm/day. Group 2 consisted of patients with Pruzansky type II mandibles who had distraction osteogenesis without prior rib grafting (n = 9). The biomechanical parameters, orthodontic treatment regimens, and complications were examined versus patient age and quality of the rib graft. Distraction osteogenesis was successfully performed in six of the rib graft patients (group 1) and in all of the group 2 individuals. On the basis of the Haminishi scale, the computed tomographic scan appearance of the regenerate was classified as "standard or external" in six of the group 1 patients and as either "agenetic" or "pillar" (fibrous union) in the remaining three patients. In group 1, the average device was expanded 23 mm (range, 20 to 30 mm). Group 2 mandibular distraction results were all classified as either standard or external, and there was an average device expansion of 22.4 mm (range, 16 to 30 mm). The length of consolidation averaged 12.6 weeks in group 1, compared with 8.5 weeks in the traditional mandibular distraction patients (group 2). The mean shift of the dental midline to the contralateral side was 2.5 mm in group 1 versus 4.0 mm in group 2. Complex multiplanar and transport distractions were successfully performed on grafts of adequate bony volume. All four patients in group 1 with tracheostomies were successfully decannulated after consolidation. Rib graft distraction complications included pin tract infections in two patients, hardware failure with premature pin pullout in one patient, and evidence of fibrous nonunions in three young patients with single, diminutive rib grafts. In group 2, there were no distraction failures. Distraction osteogenesis can be successfully performed on costochondral rib grafts of the mandible; however, the complication rate is higher than in non-rib-graft patients. Performing the technique on older, more cooperative individuals seems to reduce this risk. In addition, placement of a double rib graft or an iliac bone graft of sufficient volume to create a neomandible with greater bone stock is an absolute requirement to decrease the risk of fibrous nonunion and provide a bone base of sufficient size for retention of the distraction device and manipulation of the regenerate.

Bone Transplantation↗

[Application of distraction osteogenesis in severe maxillary hypoplasia secondary to cleft palate].

OBJECTIVE: To evaluate the effect of distraction osteogenesis in correction of severe undeveloped maxilla secondary to cleft palate and to evaluate the selection of distraction modality. METHODS: Distraction osteogenesis was performed upon 8 patients, 6 males and 2 females, aged 11 to 25 years, one with incomplete cleft palate, 4 with unilateral complete left palate, and 3 with bilateral complete cleft palate, all accompanied with severe maxillary hypoplasia. The 7 adult patients were treated by modified high-stepped Le Fort I osteotomy, the other patient, a child, was treated by Le Fort I osteotomy followed by rigid external distraction. X-ray films of skull in lateral, frontal, or panoramic positions, and X-ray film of temporomandibular joint in Schiller's position were taken pre- and postoperatively. In model surgery the accurate distraction distance was measured and the direction of distraction designed. Orthodontic therapy was started immediately after the distraction was completed and the distractor was removed after a period of 4 months' consolidation. RESULTS: The designed distraction was achieved in a11 8 patients. Except in one case with a bone defect 1 cm x 0.5 cm at the osteotomy line in the lateral wall of the right maxillary sinus, dense new bone was formed in the area of distraction in the other cases. The postoperative occlusal relationship was good and stable. No infection and other complication was found. During an average of 20 months' follow-up, the maxilla and occlusion were stable, and no relapse was found. The distance of forward distraction of the maxilla reached an average of l2 mm (5 approximately 15 mm). The SNA angle increased from 71 degree on average preoperatively to an average of 79 degree postoperatively. Both the facial appearance and occlusal relationship returned to normal in a11 the patients. CONCLUSION: Without need of bone grafting and with a stable effect and little influence on platatopharyngeal competence, distraction osteogenesis is an effective method of correcting maxillary hypoplasia secondary to cleft palate and is worthy of spreading.

Adolescent↗

[Mandibular distraction osteogenesis in the treatment of obstructive sleep apnea syndrome in children with micrognathia].

OBJECTIVE: To evaluate the treatment of obstructive sleep apnea syndrome (OSAS) in children with congenital micrognathia using mandibular distraction osteogenesis and to discuss the advantages and disadvantages of this approach. METHODS: 6 patients (4 males, 2 females) had undergone mandibular distraction osteogenesis, 12 distraction devices were placed through extraoral incision for bilateral distraction. The mean age of treatment was 1 year and 9 months (range 4 months to 9 years). Every patient had been evaluated pre and postoperatively with cephalometry. The period of consolidation was 4 - 11 weeks. The period of follow-up was from 2 to 10 months. RESULTS: The average distraction distance was 19.2 mm (range 15 to 25 mm). The osteotomy and distraction processes were smooth in all the cases, the osteogenesis was good, without infection and other complications. The posterior airway space was increased from averaged 4.5 mm preoperatively to 10. 1mm after surgery. Five children had normal respiration and sleep restored with naso-pharyngeal airway removal or tracheostomy decannulation. One patient is to receive a planned second stage of distraction with a horizontal vector. The results were stable without relapse during a follow-up period of 2 to 10 months. CONCLUSIONS: Application of mandibular distraction osteogenesis is an important component and effective in the treatment of OSAS and permits mandibular advancement in the younger child. As more experience is gained with distraction osteogenesis in the treatment of children with OSAS, the role of distraction will become better defined.

Child↗

Expression of osteotropic growth factors and growth hormone receptor in a canine distraction osteogenesis model.

Osteotropic growth factors play an important role in bone metabolism. Nevertheless, knowledge about their expression in relation to distraction osteogenesis remains limited. The aim of the present study was to determine the expression of growth hormone (GH), growth hormone receptor (GHR), insulin-like growth factor I (IGF-I), insulin-like growth factor II (IGF-II), and bone morphogenetic protein 2 (BMP-2) in distraction-induced bone regeneration. Expression of these factors was assessed during the consolidation phase, comparing distraction osteogenesis with osteotomy-induced bone formation. Real-time PCR was performed as a semiquantitative measurement of mRNA, and the relative expression levels of these factors were determined. In addition, plasma GH profiles and plasma concentrations of IGF-I, IGF-II, and insulin-like growth factor-binding protein 4 and -6 (IGFBP-4 and -6) were measured to assess their potential systemic role during bone formation. Expression of GHR, IGF-I, and BMP-2 had significantly increased in comparison with the expression of these factors in mature bone. Expression of GHR was significantly higher in distraction-induced bone regenerate than in osteotomy-induced bone. No significant differences were found for the expression of IGF-I and BMP-2 between distraction and osteotomy. Plasma concentrations of GH, IGF-I, IGF-II, IGFBP-4, and IGFBP-6 did not demonstrate any significant differences between treatment groups and controls. Upregulation of GHR expression in distraction osteogenesis may enhance sensitivity to endogenous systemic GH and thus promote consolidation of the regenerated bone. Changes in the systemic osteotropic growth factors GH, IGF-I, IGF-II, IGFBP-4, and IGFBP-6 do not seem to be of importance during distraction osteogenesis.

Animals↗

Transplantation of marrow-derived mesenchymal stem cells and platelet-rich plasma during distraction osteogenesis--a preliminary result of three cases.

Clinical results of distraction osteogenesis with transplantation of marrow-derived mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) were reviewed in three femora and two tibiae of the two patients with achondroplasia and one patient with congenital pseudarthrosis of the tibia. MSCs derived from the iliac crest were cultured with osteogenic supplements and differentiated into osteoblast-like cells. PRP, which is known to contain several growth factors and coagulate immediately by a minute introduction of thrombin and calcium, was prepared just before transplantation. Culture-expanded osteoblast-like cells and autologous PRP were injected into the distracted callus with the thrombin-calcium mixture so that the PRP gel might develop within the injected site. Transplantation of MSCs and PRP was done at the lengthening and consolidation period in each patient. The target lengths were obtained in every leg without major complications and the average healing index was 23.0 days/cm (18.8-26.9 days/cm). Although these results are still preliminary, transplantation of osteoblast-like cells and PRP, which seemed to be a safe and minimally invasive cell therapy, could shorten the treatment period by acceleration of bone regeneration during distraction osteogenesis.

Adolescent↗

Expression of connective tissue growth factor/hypertrophic chondrocyte-specific gene product 24 (CTGF/Hcs24/CCN2) during distraction osteogenesis.

To investigate the localization and expression of connective tissue growth factor/hypertrophic chondrocyte-specific gene product 24/CCN family member 2 (CTGF/Hcs24/CCN2) during distraction osteogenesis in the rat femur, we studied a total of 54 male rats (11 weeks old). We performed osteotomy in the midshaft of the right femur. After 7 days (lag phase), distraction was started, at the rate of 0.25 mm/12 h for 21 days (distraction phase) by using a small external fixator, and this was followed by a 7-day consolidation phase. Localization and expression of CTGF/Hcs24 during distraction osteogenesis in the femur were examined by immunostaining, in situ hybridization, and reverse transcriptase polymerase chain reaction (RT-PCR). Immunostaining showed the localization of CTGF/Hcs24 in various cells located in the bone-forming area around the osteotomy site. During the distraction phase, in situ hybridization showed that CTGF/Hcs24 mRNA was expressed not only in hypertrophic chondrocytes and osteoblasts but also in fibroblast-like cells and mesenchymal cells at sites of end-ochondral ossification, and not only in osteoblasts but also in pre-osteoblasts and fibroblast-like cells at sites of intramembranous ossification. RT-PCR showed higher level expression of CTGF/Hcs24 mRNA in the distracted group than in the nondistracted group. These results revealed an elevated pattern of CTGF/Hcs24 mRNA expression during distraction osteogenesis, and suggest that CTGF/Hcs24 may play some roles in the endochondral and intramembranous ossification processes that occur during distraction osteogenesis.

Animals↗

Experimental and clinical experience with distraction osteogenesis.

G.A. Ilizarov's clinical insights and experimental biology have developed into what is known today as distraction osteogenesis. Initially used for the treatment of fractures and nonunions, his methods have proven successful for limb lengthening and bone transportation. A brief history of the development of distraction osteogenesis, definition of terms, methods, and monitoring techniques are described. The primary mechanism, intramembranous ossification, is direct bone formation in uniform gradients of mineralization from a central fibrous interzone. New bone is produced from the local host surfaces and quickly remodels to the equivalent macro and microstructure. Blood supply at the focus of distraction, dependency on a latency period, different rates, and rhythms of distraction are all tested and discussed. Data from experimental tibial lengthening in more than 125 animals (dogs, rabbits, and rats) show that distraction osteogenesis provides unlimited new bone formation that remodels at daily rates ranging from 200 to 400 microns. In over 100 clinical cases, patients ranging in age from 18 months to 49 years have regenerated bone at an average rate of 213 microns in adults and 385 microns in children. Approximately 10% of these cases required supplemental bone grafts. The article proposes that distraction osteogenesis might be successfully applied in craniofacial surgery.

Adolescent↗

[Distraction osteogenesis in the treatment of hemifacial microsomia].

PURPOSE: This report presents the results of distraction osteogenesis using an extra oral device in 28 patients with different grade of vertical mandibular ramus hypoplasia. MATERIAL AND METHOD: 28 patients (aged 2 to 15 years) with hemifacial microsomia underwent unilateral lengthening of the ascending ramus using unidirectional extraoral devices (Molina distractor). 3D-CT and cephalometric radiographs were analysed to determine the placement of the mandibular osteotomy and select the appropriate placement of the distraction device. RESULT: On the basis of one-year follow-up we can conclude that excellent, stable and functional mandibular lengthening was achieved with external distraction osteogenesis with minimal complications in all our patients. Coordinated growth between maxillary and mandibular arches with stable occlusion is observed. CONCLUSION: Mandibular distraction osteogenesis has proved to be an excellent technique for the treatment of mandibular deficiency. Careful and comprehensive planning of treatment, coupled with control of the distraction vector can bring about predictable results with minimal morbidity. Nevertheless. It is our conclusion that good and effective orthodontics within the period of consolidation is the key to achieve satisfactory stability results.

Adolescent↗

Successful management of complications from distraction osteogenesis after osteosarcoma resection: a case report.

We report a complicated case of osteosarcoma of the proximal tibia. A 15-year-old boy was referred to us and underwent distraction osteogenesis reconstruction. We administered preoperative chemotherapy for five cycles. Clinical response was determined to be complete by radiography. Marginal excision was then performed with preservation of the proximal tibial epiphysis. Metaphyseal reconstruction (type 2) was performed with distraction osteogenesis. Postoperative chemotherapy also was administered for five cycles. Two years later, the patient developed a deep infection. He underwent curettage and a pedicle peroneal flap transfer, which did not cure the infection. Infected tissues were excised, and shortening-distraction was carried out with the Ilizarov frame. The infection was cured; however, a leg length discrepancy and deformity resulted from frame instability. Four years after the initial operation, the patient fractured his reconstructed leg in a traffic accident. We performed osteosynthesis, deformity correction, and lengthening with the Ilizarov method. We were able to correct the defects using distraction osteogenesis, eventually restoring normal function. Epiphyseal preservation and reconstruction by distraction osteogenesis can provide an excellent outcome, resulting in a stable reconstruction that functionally restores the native limb. Distraction osteogenesis avoids some complications but may involve others, which require detection and appropriate management.

Adolescent↗

Distraction osteogenesis may promote periodontal bone regeneration.

Distraction osteogenesis has numerous applications in the treatment of conditions affecting the dentofacial complex, from midface advancement to orthodontic tooth movement produced by transversal distraction of the periodontal ligament. The purpose of this study was to test the hypothesis that periodontium can be consistently distracted toward the tooth crown to promote periodontal bone regeneration. After the surgical production of periodontal defects in maxillary canines of 5 mongrel dogs, periodontal bone distraction was performed. Light microscopy was used for histopathological and morphometric analysis. Periodontal bone regeneration occurred in all animals. Periodontal bone regeneration in the distraction sites (Mean +/- SD: 5.45 +/- 2.01 mm) differed from that in control sites (0.008 +/- 0.67 mm; p < 0.0001). Periodontal bone distraction resulted in periodontal bone regeneration. This finding may establish periodontal bone distraction as a new treatment alternative for periodontal defects.

Alveolar Process↗

Vertical alveolar distraction osteogenesis with complications in a reconstructed mandible.

We report here a case of vertical alveolar distraction osteogenesis with many complications that required further surgical interventions. A 54-year-old man underwent mandibular resection followed by iliac bone grafting as the result of large mandibular odontogenic keratocyst. Eleven months later, alveolar vertical distraction osteogenesis was applied to the patient for prosthetic rehabilitation. Fracture of the basal bone occurred in the consolidation period, and the fracture was fixed by the titanium miniplate system. Radiographic examination after completion of distraction osteogenesis confirmed a radiolucent area in half of the distracted area between the basal bone and the transport segment, and when the distractor was removed the radiolucent area was filled with fibrous granulation tissue. The granulation tissue was removed and endosteal implants were inserted together with a bone graft. Ultimately, all implants were osseointegrated, and adequate esthetics and function of the implant-supported prosthesis were achieved.

Alveolar Bone Loss↗

Distraction osteogenesis in functional reconstruction of mandible--report of 6 cases.

OBJECTIVE: To study the application of distraction osteogenesis in mandibular function reconstruction. METHODS: Three types of mandibular distractors were used in 6 patients with different mandibular defects due to tumor resection. For 2 cases with ramus defects, specially designed distractors were used to restore the normal height of the ramus. In 1 case, the trifoci distraction principle was used and a trifoci distractor was designed. In 3 cases, vertical distractors made in Germany or China were used. The patient average age was 31.5 years old (ages ranged from 8 to 54). RESULTS: In 5 cases the mandibular lengthenings were successful according to the direction and distance chosen before distraction. In 1 case, the trifoci distraction principle was applied and a proximal 23 mm mandibular defect was successfully corrected; however, the 23 mm distal mandibular defect was not corrected because the screws for fixation of the transport block were loosened. Infection and dysosteogenesis did not occur in any cases. CONCLUSION: Distraction osteogenesis can successfully be used in mandibular functional reconstruction and is more advantageous than traditional techniques. The most favorable time for distraction osteogenesis in mandibular reconstruction is at the time of tumor resection.

Adult↗

Lengthening of muscle during distraction osteogenesis.

Chronic lengthening of immobilized, neurally intact muscle leads to the addition of sarcomeres in series. Confirmation of a similar adaptation during distraction osteogenesis is crucial for providing a rationale for a successful outcome of the intervention. When distraction osteogenesis (at < or = 1.4 mm/day) is done in skeletally immature animals, muscle adapts by creating a longer and functionally intact muscle. This is achieved through muscle growth, the proliferation of myogenic cells ultimately leading to serial addition of sarcomeres. When distraction osteogenesis is done in skeletally mature animals, however, the same distraction regimen leads to a lengthened muscle that has significant fibrosis and weakness, the latter possibly a result of partial denervation. Despite a modest but significant elevation of local insulinlike growth factor-1 in the lengthened muscles from adult animals, muscle growth is not adequate and leads to a loss of function. In adult animals, the distraction osteogenesis-induced increase in insulinlike growth factor-1 is insufficient to facilitate muscle growth during lengthening. Muscle can be targeted for future therapeutic use of insulinlike growth factor-1; however, such a therapy also may lead to increased fibrosis.

Adaptation, Physiological↗

Alveolar distraction osteogenesis for the correction of vertically deficient edentulous ridges: a multicenter prospective study on humans.

PURPOSE: The purposes of this prospective multicenter study were to evaluate the use of vertical distraction osteogenesis in the correction of vertically deficient alveolar ridges and to evaluate whether the vertical bone gained by distraction osteogenesis was maintained over time when dental implants were placed in the distracted areas. MATERIALS AND METHODS: Thirty-seven patients presenting vertically deficient edentulous ridges were treated in 4 different centers by means of distraction osteogenesis with an intraoral alveolar distractor. Two to 3 months after consolidation of the distracted segments, 138 dental implants were placed in the distracted areas. Four to 6 months later, abutments were connected and prosthetic loading of the implants began. RESULTS: The mean follow-up after initial prosthetic loading was 34 months (range 15 to 55 months). The mean bone gain obtained by distraction was 9.9 mm (range 4 to 15 mm). The cumulative success rate of the implants 4 years after the onset of prosthetic loading was 94.2%, while the implants' cumulative survival rate was 100%. No statistically significant differences were found between the different centers as far as survival and success rates of implants were concerned. DISCUSSION AND CONCLUSION: The results of this study appear to demonstrate that distraction osteogenesis is a reliable technique for the correction of vertically deficient edentulous ridges. The regenerated bone appeared to withstand the functional demands of implant loading. The survival and success rates of the implants placed in the distracted areas were consistent with those reported in the literature regarding implants placed in native bone in this patient population.

Adolescent↗

Pediatric mandibular distraction osteogenesis: the present and the future.

Pediatric mandibular distraction osteogenesis (MDO) has become a mainstay of treatment for patients with micrognathia and retrognathia. As craniofacial surgeons have gained experience with MDO, the technique has become a safe and durable means of mandibular lengthening that avoids the significant morbidity of conventional surgical treatments. The full impact of this technique has not yet been realized for pediatric patients. Although studies have confirmed durable reconstruction of mandibular length with MDO, the range of applications of this technique is currently limited. As innovative clinicians continue to apply MDO to pediatric clinical craniofacial problems not easily treated with conventional means, the field of MDO will continue to mature. This article discusses current uses and examples of potential future applications of pediatric MDO. The development of novel and creative applications of MDO will advance the management of complex craniofacial anomalies, taking the field of craniofacial surgery into the future.

Child, Preschool↗

Distraction osteogenesis for knee arthrodesis in infected tumor prostheses.

Three patients had distraction osteogenesis as a salvage method for infected endoprostheses. At the first operation, the infected prosthesis was removed and stabilization was achieved with an external fixator to preserve limb length. An additional external fixator was applied later for distraction osteogenesis after ensuring that there was no infection. Osteotomy was done at two sites on the femur, or tibia and femur, respectively, as a second operation. A third surgery was done at the docking site at the edge of the transported bone fragments. Curettage, refreshing, and soft tissue release were done to enhance bone union. The healing index was 18.3 days/cm in Patient 1, 17.7 days/cm in Patient 2, and 33.0 days/cm in Patient 3. All patients walk without a cane. It has been shown that patients can obtain a long-lasting and weight-bearable leg with our method, because their viable bone establishes biomechanical stability. Loss of knee function, a longer treatment period, and pin site treatment are the weaknesses of our method. Our method is indicated for patients in whom systemic disease can be controlled well and who have longer life expectancy.

Adolescent↗

Distraction osteogenesis of the mandible.

PURPOSE OF REVIEW: Airway obstruction and craniofacial deformities resulting from mandibular deficiency are challenging and complex clinical problems. Mandibular distraction osteogenesis is playing a rapidly expanding role in the treatment of these children and has supplanted traditional management techniques in many centers. Several recent studies have reviewed clinical experience, described technical refinements, and addressed issues in patient selection and preoperative workup. RECENT FINDINGS: The extension of mandibular distraction osteogenesis to newborns with Pierre Robin sequence or craniofacial syndromes associated with micrognathia and airway obstruction has radically altered treatment protocols at several institutions. Early bilateral mandibular distraction has obviated tracheostomy in most newborns, with low operative morbidity. In addition, early decannulation and resolution of obstruction has occurred when mandibular distraction osteogenesis was applied to selected micrognathic children. Some of these patients were tracheotomized and others presented with severe obstructive symptoms. Studies have described success with external and internal distraction techniques. Recent publications have also demonstrated the surgeon's ability to mold the regenerate safely, the dynamic characteristics of the consolidation phase, and success with secondary and tertiary distraction. SUMMARY: After 15 years of clinical use in children for craniofacial deformities, recent advances in distraction osteogenesis have obviated tracheostomy in most newborns with micrognathia and severe airway obstruction. Applications of this technique to children with airway issues related to micrognathia or retrognathia have been rapidly expanding. In addition, refinements in distraction technique have advanced treatment of nonairway-related mandibular deformities.

Airway Obstruction↗