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PubMed1999

Treatment planning and biomechanics of distraction osteogenesis from an orthodontic perspective.

As in traditional combined surgical and orthodontic procedures, the orthodontist has a role in the planning and orthodontic support of patients undergoing distraction osteogenesis. This role includes predistraction assessment of the craniofacial skeleton and occlusal function in addition to planning both the predistraction and postdistraction orthodontic care. Based on careful clinical evaluation, dental study models, photographic analysis, cephalometric evaluation, and evaluation of three-dimensional computed tomographic scans, the orthodontist, in collaboration with the surgeon, plans distraction device placement and the predicted vectors of distraction. Both surgeon and orthodontist closely monitor the patient during the active distraction phase, using intermaxillary elastic traction, sometimes combined with guide planes, bite plates, and stabilization arches, to mold the newly formed bone (regenerate) while optimizing the developing occlusion. Postdistraction change caused by relapse is minimal. Growth after mandibular distraction is variable and appears to be dependent on the genetic program of the native bone and the surrounding soft tissue matrix. A significant advantage of distraction osteogenesis is the gradual lengthening of the soft tissues and surrounding functional spaces. Distraction osteogenesis can be applied at an earlier age than traditional orthognathic surgery because the technique is relatively simple and bone grafts are not required for augmentation of the hypoplastic craniofacial skeleton. In this new technique, the surgeon and the orthodontist have become collaborators in a process that gradually alters the magnitude and direction of craniofacial growth.

Biomechanical Phenomena↗
PubMed1990

[Ilizarov's distraction osteogenesis using the mono-fixator system and initial clinical experiences with the injured lower leg].

Distraction osteogenesis, as developed by Ilizarov, allows the limbs to be lengthened and intercalary defects to be filled by bone transport without the use of bone grafts. In five patients with traumatic sequelae (fractures of the lower leg), unilateral dynamic mono_fixation and a special distraction apparatus were used for application of the Ilizarov technique. With the distraction device, gradual distraction of the osteotomy surfaces (1/3 mm in three steps per day) is easy for the patients to perform. In three cases distraction osteogenesis was used to correct shortening of the lower leg and in two cases for bridging a tibial defect due to an infection in the plate osteosynthesis. In all cases, the course of treatment and bone healing were uneventful. Based on our first clinical experiences, we believe that mono_fixation provides appropriate stability and the distraction apparatus permits appropriate bone transportation for successful distraction osteogenesis in the tibia.

Adolescent↗
PubMed2002

Osteosarcoma around the knee. Intraepiphyseal excision and biological reconstruction with distraction osteogenesis.

In 11 patients juxta-articular osteosarcoma around the knee was treated by intraepiphyseal excision of the tumour and reconstruction of the bone defect by distraction osteogenesis. Preoperative and postoperative chemotherapy was given to eight patients with high-grade tumours. The articular cartilage of the epiphysis and a maximum of healthy soft tissues were preserved. Distraction osteogenesis was then carried out. The mean gain in length was 9.7 cm. Full function of the limb was preserved in all except one patient, with a mean follow-up of 53.8 months. Treatment of juxta-articular osteosarcomas around the knee with joint preservation and biological reconstruction using distraction osteogenesis can give excellent functional results.

Adolescent↗
PubMed2000

Distraction osteogenesis of the ascending ramus for mandibular hypoplasia using extraoral or intraoral devices: a report of 8 cases.

PURPOSE: This report presents the results of distraction osteogenesis using unidirectional extraoral and intraoral devices in 8 patients with different grades of vertical mandibular ramus hypoplasia. PATIENTS AND METHODS: Eight patients with hypoplastic mandibles underwent unilateral lengthening of the ascending ramus using unidirectional extraoral or intraoral devices. Intraoral mandibular distraction was performed on 5 patients with deficiencies of the vertical ramus up to 24 mm. External devices were used in 3 patients with more severe hypoplasias. An intraoral osteotomy was performed, and progressive distraction at rates of 0.5 mm/12 hours was initiated after 5 days. Once the desired length was reached, the device was maintained in place for 8 to 12 weeks. Three-dimensional computed tomography scans were taken in all the patients to plan the procedure and to compare the changes postoperatively. RESULTS: Successful distraction osteogenesis was achieved in all patients. The amount of mandibular lengthening ranged from 17 to 32 mm. Complications with the external devices such as rotation of the proximal bony fragment (2 cases) and loosening of the external screws at the end of the consolidation period (1 case) were observed. CONCLUSIONS: The results suggest that the intraoral device can be used as the method of choice for distraction osteogenesis of the ascending ramus of the mandible in patients with large deficiencies. Preoperative and postoperative 3-dimensional computed tomographic scans are essential in treatment planning.

Bone Screws↗
PubMed2003

Response of Schwann cells in the inferior alveolar nerve to distraction osteogenesis: an ultrastructural and immunohistochemical study.

The biological mechanisms of nerve adaptation to distraction osteogenesis have not yet been elucidated. This study observed response of Schwann cells in the inferior alveolar nerve (IAN) following mandibular lengthening by electron microscopy and immunohistochemistry of S-100 protein, a specific marker of Schwann cells. Unilateral mandibular distraction (10mm elongation) was performed in nine young adult goats. Three animals were sacrificed at 7, 14 and 28 days after completion of distraction, respectively. The distracted IAN specimens and control nerves (from the contralateral sides) were harvested and processed for histological, ultrastructural and immunohistochemical examinations. Wallerian degeneration was observed in the distracted IAN, and Signs of axonal regeneration, as well as many activated Schwann cells were seen in the lengthened nerves. The expression of S-100 protein increased significantly at early stage of distraction osteogenesis, but almost returned to the normal level at 28 days after distraction. This study suggests that Wallerian degeneration caused by mechanical stretching may stimulate Schwann cells to enter a proliferated and activated state. Schwann cells and S-100 protein appear to play crucial roles in axonal regeneration that contributes to nerve adaptation to gradual distraction. Therefore, the IAN injury caused by mandibular gradual distraction was not serious; it seems to recover totally through a complicated repair mechanism.

Adaptation, Biological↗
PubMed2000

Primary resective shortening followed by distraction osteogenesis for limb reconstruction: a comparison with simple lengthening.

Resective distraction osteogenesis is a new approach to treat segmental diaphyseal bone defects by primary limb shortening and secondary distraction osteogenesis from the same site. A rabbit model was introduced to compare the bone-regeneration characteristics of this technique with those of simple lengthening procedures. Twenty-four skeletally mature New Zealand White rabbits were divided into two equal groups. In the test group, limbs were lengthened after a 10-mm segmental diaphyseal bone resection and limb shortening. In the control group, a simple subperiosteal osteotomy for limb lengthening was performed without resection. New bone formation was evaluated mechanically, radiologically, histomorphometrically, and densitometrically. Bone bridging occurred in all animals. Normalized mechanical values for the newly reconstructed tibiae demonstrated similar torsional stiffness (71+/-3.3 compared with 71+/-8.2%; p = 0.95) and strength (64+/-5.3 compared with 68+/-7.3%; p = 0.66) in the two groups. The average normalized callus diameter was significantly greater in the test group than in the control group (p < 0.01). The remodeling index calculated from densitometry, however, showed a significantly less progressed stage of remodeling in the test group (p < 0.05). Histomorphometric analysis of the callus center supported this finding, showing significantly lower values for trabecular thickness (p < 0.05) and total bone volume (p < 0.01) in the test group. The results demonstrated the possibility of new bone formation after resection and monofocal shortening. This suggests a new therapeutic option to treat diaphyseal segmental bone defects.

Absorptiometry, Photon↗
PubMed2003

Histomorphometry of distraction osteogenesis during experimental tibial lengthening.

OBJECTIVES: The aim of the current study was to analyze distraction osteogenesis histomorphometrically to investigate the amount of enchondral ossification adjacent to intramembranous ossification. STUDY DESIGN: Species-specific, longitudinal time study. METHODS Lengthening of 25% of the right tibia was performed in 24 beagle dogs by callus distraction after osteotomy and application of a ring fixator. Distraction was started at the fifth postoperative day with a distraction rate of 0.5 mm twice a day. Twelve dogs were killed at the end of the distraction phase of 25 days (group A) and the remaining 12 dogs after an additional consolidation period of 25 days (group B). The tibia was removed from the distracted right leg and from the left control side of each animal, and longitudinal sections were cut and stained with Pentachrome. In all tibiae, an area of 0.5 x 2.4 cm within the endosteal bone was evaluated histomorphometrically with a Merz grid, and the results were compared between distraction and control side as well as between the dogs of group A and group B. RESULTS: On the distraction side, the typical signs of an increased de novo bone formation with a significant increase of osteoblasts and osteoid in group A, as well as an additional significant increase of bone volume and trabecular thickness in group B, were found. In all distraction cases, islands of cartilage formation, which underwent enchondral ossification, were found, besides membranous ossification. The ratio between membranous and enchondral ossification was found to be five to one. CONCLUSION: Bone formation during distraction osteogenesis results from both membranous and enchondral ossification.

Animals↗
PubMed2005

Reconstruction of mandibular symphyseal defects by trifocal distraction osteogenesis: an experimental study in Rhesus.

Mandibular symphyseal defects caused by tumor surgery, trauma, or congenital misshape can produce maxillofacial deformity and functional handicap. Recently, the technique of distraction osteogenesis has become a valuable reconstructive method for craniofacial bone defects. Four adult rhesus monkeys were used in this study. The anterior mandibulectomy (ranged from canine to canine) was performed, and bilateral transport segments (ranged from first premolar to first molar) were created. Custom-made multiplanar distractors were applied for the reconstruction of the monkeys' artificial mandibular symphyseal defects by trifocal distraction osteogenesis. After a delay period of 7 days, the bilateral transport discs were distracted forward and inward simultaneously. Serial X-ray and three-dimensional CT films were taken within the experimental period. Two monkeys were sacrificed at 8 and 16 weeks, respectively, after the completion of distraction. The distracted calluses and united areas between bilateral transport discs were harvested and processed for histological examination. The mandibular symphyseal defects in all animals were repaired successfully and the anterior mandibular contours were similar to the normal ones. Perfect bone regeneration in the distraction gaps was found, and fibro-bony union between the bilateral transport segments was observed in the midline region at 16 weeks after the end of distraction. The success of distraction osteogenesis for repair of mandibular symphseal defects in monkeys by this distractor may provide an alternative method to reconstruct the anterior part of mandible.

Animals↗
PubMed2006

Transport distraction osteogenesis using nitinol spring: an exploration in canine mandible.

Some experiments in rabbits have presented the potential feasibility of using shape memory alloy spring for continuous distraction osteogenesis. To confirm the effectiveness of such method, we established canine models for the exploratory experiments of transport distraction osteogenesis using nitinol springs. Simple devices, including an internal 60-mm long sinusoid-shaped nitinol springs were used in the study. All dogs needed only one operation. In the operation, osteotomy was performed to create a 40-mm unilateral segmental mandibular body defect and a tooth-bearing transport bone disc. After reconstructive fixation of the remnant mandible, the spring was constricted and anchored across the distraction gap to activate transport distraction immediately. At the second experimental stage, an ePTFE sheet was further fixed to protect the defect and distraction gap before closing the incision. Control dogs underwent the same operation except for anchoring of the spring to examine the spontaneous bone regeneration. Automatic bone transportation, as a gradual slowdown process, was observed under the effect of the spring. The transport disc could get to the opposite side of the defect, or stopped halfway when ePTFE sheet intervened. Mandibular reconstruction was achieved in all these dogs and better in dogs with sheet protection. No integrated bone mass was found in the defect of control dogs. The study further proves that continuous distraction osteogenesis using nitinol springs is a practical technique, although the devices need more improvement for better control of the process of distraction and the quality of regenerated bone.

Alloys↗
PubMed2005

[Quantitative histomorphometric observation of distraction osteogenesis during mandibular lengthening].

PURPOSE: To evaluate the regenerating bone during mandibular distraction osteogenesis by bone histomorphometry combining tetracycline bone labeling fluorescence microscopy. METHODS: Osteotomy was performed on bilateral mandibles in ten goats. A custom-made distractor was applied to lengthen the mandible at a rate of 1 mm/d (0.5 mm/12 hrs) for ten days. Every two animals were sacrificed at 10 d, 15 d, 25 d, 35 d and 45 d postoperatively. Two additional goats were used as normal control. The bony specimens were collected and prepared for bone histomorphometry and tetracycline bone labeling fluorescence microscopy with analysis of variance. RESULTS: From 10 days subgroup to 45 days subgroup, bone volume fraction,trabecular thickness,trabecular number and volume density were gradually increased (P<0.05), while trabecular separation distance and surface density were gradually decreased (P<0.05). Between 15 days subgroup and 45 days subgroup,the index of osteoblast was significantly higher than normal control (P<0.05) and index of osteoclast was increased gradually (P<0.05). Compared with normal control, bone formation rate was accelerated by thousand times between 15 days subgroup and 45 days subgroup (P<0.05). CONCLUSIONS: During the process of mandibular distraction osteogenesis, the bone formation is active, the newly formed bone trabecula gradually become mature, and the remodeling activities of regenerated bone are enhanced gradually. The rate of bone formation within distraction period is faster than consolidation period.

Animals↗
PubMed2000

Rapid orthodontic tooth movement into newly distracted bone after mandibular distraction osteogenesis in a canine model.

Orthodontic tooth movement through recently distracted fibrous bone tissue has not been investigated previously. We hypothesized that a tooth can be moved into the fibrous new bone created by the distraction process at a rapid rate. Four mature beagle dogs were used in this study. An edentulous space was created in 2 weeks by using a bone-borne intraoral distraction device on each side of the mandibular body between the third and fourth premolars. Calibrated elastic threads with 50 g of orthodontic force were applied to move the fourth premolar into the edentulous space for 5 weeks. On one side, the tooth was moved simultaneously with distraction; and on the opposite side, it was initiated immediately after the cessation of distraction. The fourth premolars were moved 1.2 mm per week. The results indicated that the best time to initiate tooth movement was immediately after the end of distraction. With this approach, most of the periodontal support was preserved after orthodontic tooth movement. In contrast, moderate to severe alveolar bone loss was noted in the fourth premolars moved simultaneously with distraction. This is one of the first experimental studies to demonstrate successful rapid orthodontic tooth movement into an edentulous space newly created by distraction osteogenesis. Clinical implications of these results may be applied to relieve severe dental crowding and to correct sagittal or transverse dental arch discrepancies.

Animals↗
PubMed2003

Maxillary anterior segmental advancement by using distraction osteogenesis: a case report.

After the first clinical application of distraction osteogenesis (DO) to correct mandibular deformity was reported in 1992, various applications such as maxillary or midface advancement, temporomandibular joint reconstruction, alveolar augmentation, and mandibular widening have been described in the oral and maxillofacial region. Block et al and Altuna et al first examined anterior segmental DO experimentally in the maxilla and reported successful results. After these studies, DO has been used clinically for the total advancement of the maxilla or midface. But no clinical application of DO for maxillary anterior segmental advancement was found by a review of the literature in English. In this article, we present a case with a skeletal Class III abnormality resulting from a maxillary deficiency, which was treated by using anterior segmental DO.

Adult↗
PubMed1997

Distraction osteogenesis for correction of transverse mandibular deficiency: a preliminary report.

PURPOSE: This article reviews the early results with distraction osteogenesis to correct transverse width deficiencies in the mandible. PATIENTS AND METHODS: Nine patients with congenital/developmental maxillofacial skeletal deformities had distraction osteogenesis performed. All patients had study casts and cephalometric and dental radiographs obtained before and after surgery. Eight of the nine patients also had simultaneous surgical assisted-rapid palatal expansion (SA-RPE). The other patient had nonsurgical RPE. RESULTS: Successful completion of the planned mandibular symphyseal distraction was achieved in eight of nine patients. Four of the nine experienced failure of the distraction appliance because of stripping of the distraction tram. Three of them underwent reoperation. The mean expansion achieved in the anterior mandible measured at the canines was 3.9 mm. CONCLUSIONS: These preliminary results suggest that distraction osteogenesis is a viable option to correct transverse discrepancies of the mandible.

Activator Appliances↗
PubMed1998

Evaluation of the mechanical environment during distraction osteogenesis.

Physical forces have been hypothesized to direct the process of bone regeneration during distraction osteogenesis. However, despite significant clinical experience, relatively little is known about how the mechanics of distraction influence bone formation. This study investigated net fixator forces and strains in the distraction callus during bilateral lengthening of tibiae in New Zealand White rabbits. Distractions yielded a classic viscoelastic response with a sharp increase in fixator force, followed immediately by significant relaxation. Tension acting on mesenchymal gap tissue caused by distraction was estimated to reach more than 30 N by the time full lengthening was achieved. Average maximum cyclic strains within the distraction zone during ambulation were estimated to be 14% to 15% and supported by the results of fluoroscopic imaging. Paradigms for fracture healing have hypothesized that such strains are incompatible with new bone formation. The documented clinical success of distraction osteogenesis at stimulating large volumes of new bone suggests that other mechanisms that warrant additional investigation may be at work during distraction.

Animals↗
PubMedDate not supplied

Distraction osteogenesis versus autogenous onlay grafting. Part II: biology of regenerate and onlay bone.

PURPOSE: Few studies have directly compared the quality of bone generated by distraction osteogenesis with that generated by autogenous onlay grafting. The purpose of this study was to compare rates of bone turnover at 5 months in bone produced by distraction osteogenesis and onlay grafting. MATERIALS AND METHODS: Alveolar defects created in jaws of American foxhounds were augmented with distraction osteogenesis or onlay grafting and allowed to heal for 5 months. The animals were then sacrificed and the jaws were resected and prepared for decalcified and undecalcified histologic examination. RESULTS: Both procedures produced bone containing a mixture of haversian systems and trabecular bone. A significantly greater ratio of osteoblast-covered bone surface to total trabecular bone surface (mean +/- SEM) was noted in distraction bone (0.124 +/- 0.049) compared to onlay bone (0.081 +/- 0.048) or control host bone (0.085 +/- 0.042 microm) (P < .05). In addition, significantly (P <.05) greater numbers of osteoclasts per microm of bone surface were noted in distraction bone (0.939 +/- 0.07) compared to onlay bone (0.605 +/- 0.06) or control host bone (0.725 +/- 0.08). No differences in rates of mineralization were noted between the groups. DISCUSSION: While bone from both experimental groups appeared adequate for implant placement, distraction bone appeared to be remodeling at a higher rate than either onlay or control bone. CONCLUSION: Given that the state of healing of the bone in each of these comparative groups was examined at a static point in time, it is premature to draw conclusions about the efficacy of one procedure over the other.

Acid Phosphatase↗
PubMedDate not supplied

Physiologic weight-bearing and consolidation of new bone in a rat model of distraction osteogenesis.

To evaluate the effect of weight-bearing on consolidation of the regenerate in distraction osteogenesis, unilateral femoral lengthenings were performed in two groups of rats. In the first group (n = 19) unrestricted weight-bearing was permitted postoperatively, while in the second (n = 18) weight-bearing was prevented via a through-knee amputation. In both groups the distraction protocol involved a 3-day latency period, four daily 0.5-mm lengthenings, and 35 days of consolidation. Healing was evaluated with serial radiographs (days 0, 7, 14, 28, and 35) and at sacrifice with measurement of ash weight, quantitative histology, and mechanical testing. Histomorphometry revealed that the callus in the weight-bearing animals was significantly larger than in the non-weight-bearing animals, primarily due to increases in periosteal and interzone new bone; there was no significant increase in cartilage formation. Weight-bearing had no significant effect on the stiffness, strength, or mineral content of the regenerate. These findings suggest that weight-bearing may be capable of influencing consolidation of the regenerate in distraction osteogenesis. Additional studies will be required to determine the optimal loading for new bone formation.

Animals↗
PubMed2003

Mandibular lengthening by distraction osteogenesis for treatment of obstructive sleep apnea syndrome: a case report.

A 31-year-old man who had been diagnosed with obstructive sleep apnea syndrome (OSAS) due to retrognathia was referred to our hospital. Before treatment, the angle of the sella-nasion-point B (SNB) was 67 degrees. The lowest oxygen saturation (SpO2) during sleep was 77%, the longest-running episode of sleep apnea was 128 seconds, and his apnea index (AI) was 29.9. He underwent bilateral horizontal mandibular distraction osteogenesis using intraoral distraction devices. After mandibular distraction, SNB increased to 72 degrees. The lowest SpO2 during sleep increased to 85%, the longest-running episode of sleep apnea decreased to 40 seconds, and his AI decreased to 4.1 (within normal range). No marked recurrence of OSAS was observed even at one year after mandibular distraction. This report suggests that mandibular lengthening by distraction osteogenesis is an effectual method for the treatment of OSAS due to retrognathia.

Adult↗
PubMed1999

Transoral maxillary distraction osteogenesis of an unrepaired bilateral alveolar cleft.

Distraction osteogenesis has gained acceptance as a viable modality for lengthening hypoplastic skeletal structures in the maxillofacial region. A case of the application of this technique to advance the maxilla in an unrepaired bilateral alveolar cleft via a transoral approach is presented. The distraction devices were applied bilaterally to the zygomatic buttress region with the activating arms protruding from the oral cavity. A high Le Fort I osteotomy was performed under general anesthesia and, prior to distraction, the three maxillary segments were unified with an occlusal acrylic splint. Activation was begun 6 days after placement, at a rate of 1 mm per day, until the planned maxillary advancement had been achieved. An 8-week period of consolidation was allowed prior to removal of the devices.

Alveoloplasty↗