Successful Distraction Osteogenesis Research Articles

Intramembranous bone formation after callus distraction is augmented by increasing axial compressive strain.

The mechanical environment is a primary factor in the success of distraction osteogenesis. It is known that the interfragmentary movement during the distraction and maturation phase effects the callus formation. In addition to cyclic compression, other movements like shear and bending influence the bone formation process as shown in previous callus distraction studies. Reports of cartilage presence and endochondral ossification in the regenerative zone have been associated with a lack of fixation stability and delayed healing. So far the effects of the direction of interfragmentary movements could not be studied separately. By means of a unique lateral callus distraction model, we investigated the effects of small (0.1 mm) and moderate (0.6 mm), purely axial compression on ossification during callus maturation in sheep. A distraction device incorporating a mobile titanium plate was mounted on the tibia. Following lateral callus distraction, electromechanically controlled movements allowed purely axial cyclic compression of the tissue regenerate. Seven weeks post-operatively, the tissue regenerates were investigated using μCT, histology and immunohistochemistry. The larger amplitude significantly increased bone formation (Fractional bone volume: 19.4% vs. 5.2%, p = 0.03; trabecular thickness: 0.1 mm vs. 0.06 mm, p = 0.006; mean spicule height: 2.6 mm vs. 1.1 mm, p = 0.02) however, no endochondral ossification occurred. The elimination of shear movement, unimpaired neovascularization as well as the tensile strain stimuli during the distraction phase suppressing chondrogenic differentiation may all contribute to the absence of cartilage. In clinical application of distraction osteogenesis, moderate axial interfragmentary movement augments intramembranous ossification provided shear strain is minimized.

Segmental Maxillary Distraction Osteogenesis With a Hybrid-Type Distractor in the Management of Wide Alveolar Cleft.

To investigate segmental maxillary distraction osteogenesis (DO) with hybrid-type distractor in the management of wide alveolar cleft. Six patients underwent segmental DO with a hybrid-type distractor. After the success of DO and 3-month consolidation period, removal of the distractor was accompanied by alveolar bone graft with iliac bone. Panoramic radiograph and computed tomography scanning were taken preoperatively (T0) and the day after distractor removal (T1). The crest distance between the long axis of cleft nearby teeth was measured. All patients completed the DO period, and the succeeding alveolar bone graft healing was uneventful. The mean cleft distance decrease was 12.05 mm (range: 10.1-13.5 mm). As for the mobility degree record of abutment tooth in the transport segment recorded, 6 patients were grading I° at T0, while 5 patients were grading I° and 1 patient was grading II° at T1. Segmental maxillary DO with the hybrid-type distractor is successful to reduce the cleft width in these cases, and it is promising in the treatment of wide dental alveolar cleft, especially for the adult patient.

Significance of distraction osteogenesis of the craniomaxillofacial skeleton – A clinical review after 10 years of experience with the technique

IntroductionDistraction osteogenesis (DO) has been applied to the field of craniomaxillofacial surgery for more than two decades. Although relevant factors for successful distraction osteogenesis are well known there are ongoing controversies about indications and limitations of the method and there is still a lack of evidence based data.Since 2003 the principle of gradual lengthening has been applied to patients affected by different types of skeletal craniomaxillofacial deficiency within individualized treatment protocols at the Campus Virchow Klinikum – Charité Universitätsmedizin Berlin – by the same surgical team. The records of these patients were reviewed in order to assess the significance of the technique within the spectrum of a craniomaxillofacial department.During 10 years DO has been applied in 80 patients representing less than 1% of all patients that have been treated since 2003. Review of the protocols showed a heterogeneous group with a wide variance of parameters, the age ranging from 2½ to 51 years. Internal distraction devices were used in all cases and individually selected with respect to optimal stability during active distraction and consolidation phase. Although distraction related complications occurred the majority of procedures ended up with the favoured result and skeletal stability. However additional reconstructive surgery was required despite successful distraction in the majority of patients.Although DO has a low significance with respect to overall patient counts the method is a powerful tool within individual therapeutic concepts for the surgical correction of craniofacial anomalies that are characterized by skeletal deficiencies and should be seen as addendum to other surgical options. Predictable and stable results can be expected if the basic principles of the method are regarded.

An Isogenic Model of Murine Mandibular Distraction Osteogenesis

The advent of stem cell-based therapies makes current models of mandibular distraction osteogenesis unwieldy. We thereby designed an isogenic model of distraction osteogenesis whose purpose was to allow for the free transfer of cells and components between rats. As immune response plays a significant role in healing and prevention of infection, an immune-competent mode is desirable rather than an athymic rat/xenograft model. The purposes of this study were as follows: (1) to replicate established models of distraction osteogenesis in a rodent model using an isogenic rat strain, and (2) to characterize the differences between inbred, isogenic rats and outbred rats in mandibular distraction osteogenesis via radiomorphometry and biomechanical response analysis. We demonstrated successful distraction osteogenesis to 5.1 mm in all Lewis (isogenic) rat mandibles as well as all Sprague-Dawley (outbred) rat mandibles, with no significant difference in volume-normalized radiomorphometrics, trending difference in non-volume-normalized radiomorphometrics and significant differences in biomechanical response parameters. We attribute the differences demonstrated to the decreased size of the Lewis rat mandible in comparison to Sprague-Dawley mandibles. We also provide information with caring with the additional needs of the Lewis rat. Given these differences, we find that Lewis rats function as an excellent model for isogenic mandibular distraction osteogenesis, but data procured may not be comparable between isogenic and nonisogenic models.

Distractor With Supporting Computer Program for the Reconstruction of Arc Defects in Mandible by Distraction Osteogenesis

Distraction osteogenesis as a technique seems to be a promising method in craniofacial bone lengthening and reconstruction through the process of bone and soft-tissue regeneration under stimulation of gradual tensile stress. Distractor plays a very important role especially in the reconstruction of large, irregular bone defects. We designed a new-type distractor and supporting computer program for the reconstruction of arc defects in the mandible by distraction osteogenesis. This distractor was applied for the reconstruction of the monkeys' artificial mandibular median defects. Owing to computer program, perfect distracting plan was made to finish this task. X-ray files showed that the mandibular defects in all animals were repaired successfully, and the anterior mandibular contours were similar to the normal ones. The success of distraction osteogenesis for repair of mandibular median defects in monkeys suggests that this distractor and supporting computer program met the needs of the reconstruction of arc defects in the mandible by distraction osteogenesis.

Effects of Different Distraction Frequencies on Axon Morphometry Following a Two-Month Consolidation Period in a Rabbit Model

Despite advances in limb lengthening, neurovascular complications still occur. Two key parameters for successful distraction osteogenesis are 1) an adequate period of consolidation and 2) distraction frequency. Several studies have described decreases in soft-tissue resistance and improved nerve conduction with high vs. low frequency distraction. Clinically, a distraction rate of 1 mm/day, to 30% of original length, followed by an appropriate consolidation period is often employed. Most limb lengthening peripheral nerve studies describe nerve morphometry either immediately following distraction termination or following distraction at a rate greater than 1 mm/day. Thus, the impact of clinically physiologic limb lengthening on the peripheral nerve remains unclear. The goals of this study were to determine the effects of clinically appropriate limb lengthening at high and low distraction frequencies on internodal length and nerve morphology (diameter and composition).

The Determinants of Successful Distraction Osteogenesis of the Mandible in Hemifacial Microsomia From Longitudinal Results

The purpose of this study was to investigate sagittal, vertical, asymmetric skeletal characteristics that could determine successful distraction osteogenesis (DO) of the mandible in patients with hemifacial microsomia using longitudinal follow-up data. Lateral and posteroanterior cephalometric radiographs before DO (T0), after DO (T1), and after retention (T2) were analyzed to investigate initial skeletal characteristics, DO effect, and retention. From the measurements at T2, patients were classified into group 1 (good retention results, N = 10) and group 2 (poor results, N = 9). Sagittal, vertical, dental, and asymmetric variables were measured. The differences at each stage and during T0-T1 and T1-T2 between two groups were compared by Mann-Whitney u test, Wilcoxon signed rank test and ANOVA test. Pruzansky type significantly influenced the success or failure of DO. At T0, group 2 showed more retrognathic mandible, smaller ramus height, larger gonial angle, more inward ramus inclination of the affected side, and more chin point deviation to the affected side than did group 1. The major effects of DO on group 1 were lengthening of the ramus height, forward positioning of the mandible, increase of gonial angle, counterclockwise rotation caused by a decrease of the articular angle, increase of ramus inclination of the affected side, and improvement of occlusal canting and chin point deviation. However, by DO, group 2 showed clockwise rotation of the mandible, and less increase of the ramus height than did group 1. After retention, group 2 showed counterclockwise rotation of the mandible and little growth of the ramus height. Group 1 showed reverse tendency. These factors could contribute to the difference in long-term results between two groups.

Internal Distraction Osteogenesis With a Unidirectional Device for Reconstruction of Mandibular Segmental Defects

To present the authors' clinical experience with unidirectional internal distraction devices to reconstruct mandibular defects. Five patients have been treated with mandibular distraction osteogenesis to reconstruct different acquired segmental defects. These mandibular defects (35 to 80 mm in length) were reconstructed by means of internal distraction devices with a transcutaneous activator. All the patients underwent complete resection of the affected bone and immediate placement of the distraction device on the remaining mandible. The results' analysis was based on clinical observation, postoperative radiographs, histopathologic findings and 3-dimensional computed tomographic scans. Successful distraction osteogenesis was achieved in 3 cases. In 1 case, extensive intraoral exposure of the device was observed, resulting in a failure of the procedure. One patient died of distant metastases 4 months after the resective surgery. Because of the limited number of cases, this study is preliminary. However, considering the good experimental and clinical results, this new technique offers an alternative for patients with segmental mandibular defects in which, because of local or general reasons, a more aggressive procedure should be avoided.

“Cat’s Cradle” Midfacial Fixation in Distraction Osteogenesis After Le Fort III Osteotomy

Distraction osteogenesis has provided a powerful technique for the treatment of severe midfacial hypoplasia. Skeletal fixation is a critical component of successful distraction osteogenesis. This is a report on the development of a new approach to bone fixation for distraction osteogenesis of the midface, based on circumferential suspension of the entire midfacial skeleton using surgical wires placed through the soft palate. This technique offers the advantages of (1) complete control of the attitude of the midface in terms of a precise dispersion of forces that can determine the desired pitch, yaw, and roll of this skeletal complex during the active phase of distraction, (2) being compatible with young children in the deciduous dentition stage because it obviates the need for rigid fixation devices on the maxillary lateral walls in the proximity of numerous dental follicles of the unerupted adult dentition, (3) actually serving as the instrument for posterior maxillary "lift" in cases of skeletal open bite malocclusions (frequently seen in the craniosynostoses), thereby allowing the clinician to determine the final occlusal and palatal planes and simultaneously close the open bite. An illustrative case of a 5(1/2)-year-old girl with Apert syndrome is presented wherein her ventilatory obstruction and ocular proptosis were significantly improved.

Bilateral mandibular distraction in adult dogs with an epiperiosteal distractor

We tested the function and efficiency of a new intraoral, bone-borne distraction device for mandibular lengthening, and the effect of bilateral transsection of the inferior alveolar arteries on osteogenesis in adult dogs. Nine adult Beagles had bilateral complete mandibular osteotomies and epiperiosteal placement of the distractor. After 7 days, the mandibles were distracted at 1 x 1mm/day, 1 x 0.5 mm/day or 2 x 0.25 mm/day for 15 or 30 days, respectively. Hemimandibles were harvested after 1, 14, or 42 days consolidation and evaluated clinically, radiographically and histologically. The mean distraction achieved was 11 mm (range 4-16 mm). New bone formation and clinical stability increased with increasing consolidation time and was independent of the distraction protocol used. Osteogenesis at the distal and proximal mandibular fragments did not differ. In 10/18 distraction sites, wound dehiscences compromised osteogenesis. The new epiperiosteal distractor permitted successful distraction osteogenesis despite complete bilateral osteotomy with section of the medullary vessels in adult dogs.

Mechanobiology of mandibular distraction osteogenesis: experimental analyses with a rat model

We analyzed mechanobiological influences on successful distraction osteogenesis (DO). Mandibular distraction surgeries were performed on 15 adult male Sprague–Dawley rats. Animals underwent gradual distraction (GD), progressive lengthening by small increments (5-day latency followed by 0.25 mm distractions twice daily for 8 days followed by 28-day maturation period). Distracted hemimandibles were harvested on postoperative days (POD) 5, 7, 10, 13, and 41. Load-displacement curves were then recorded for ex vivo distractions of 0.25 mm and stresses determined. Histologically, new bone formation appeared in GD specimens on distraction day 2 (POD 7), filling 50–60% of the gap by distraction day 8 (POD 13), with nearly complete bony bridging at end maturation (POD 41). Average tensile strains imposed by each incremental distraction ranged from approximately 10% to 12.5% during distraction days 2–8 and were associated with bone apposition rates of about 260 μm/day. Because this GD protocol was previously determined to be optimal for DO, we conclude that strains within this range provide an excellent environment for de novo bone apposition. Distraction caused tissue damage in distraction day 2, 5, and 8 specimens as evidenced by distinct drops in the load/displacement curves. Taken together, our interpretation of these data is that daily distractions cause daily tissue damage which triggers new mesenchymal tissue formation.

Intraoral mandibular distraction osteogenesis: special attention to treatment planning

Purpose: To demonstrate our experience using internal devices for unidirectional distraction osteogenesis in treating different mandibular hypoplasias (with or without maxillary deformities). An algorithmic table for diagnosis, and treatment planning is presented. Patients and methods: Twenty internal distraction devices were used in 16 patients with mandibular hypoplasia. Deficiency in length of the mandible was calculated on three-dimensional computed tomography scans. The device was activated by a transcutaneous pin on the fifth postoperative day. Distraction was achieved at rates of 0.5 mm/12 h. After a variable period of consolidation the devices were removed. Mean follow-up was 18 months. Results: Successful distraction osteogenesis was achieved in all patients. No premature consolidation or pseudoarthrosis was observed. Improvement of facial aesthetics was produced in all cases. Final occlusion was excellent in those cases where no simultaneous maxillary deformity was present. Orthodontic treatment was applied in all cases. Results remained stable one year postoperatively. Conclusions: The occlusal results obtained in this series show that we can plan distraction as a definitive treatment in cases with isolated mandibular hypoplasia. When an additional maxillary deformity is present, mandibular distraction must be performed first if indicated, but a maxillary procedure will be necessary later.

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 tomography scans are essential in treatment planning.

Successful distraction osteogenesis across a growing cranial suture without an osteotomy.

The application of distraction osteogenesis to the membranous bones of the craniofacial skeleton and its effects on cranial volume and overall skull shape have not been fully studied. This pilot study was designed to compare distraction of a cranial suture in the rabbit model with distraction across an osteotomy and to evaluate the response of the suture both grossly and histologically. Additionally, the need for a period of rigid fixation after distraction was evaluated. Calibrated distraction of either the coronal suture or an osteotomy in the midsection of the parietal bone using an internal distractor (Synthes Maxillofacial, Paoli, Pa.) was studied in juvenile and adult New Zealand White rabbits. Skull growth and distraction were followed by serial cephalograms, and bone biopsies of the distracted sites were obtained after death for histologic evaluation. Craniometric analysis of the skulls was also performed. There was significantly greater mean marker separation in the juvenile suture distraction group (6.6 +/- 0.2 mm; n = 3) than in the control group (2.2 +/- 0.2 mm; p < 0.01). Marker separation was also significantly greater across the parietal osteotomy (6.4 +/- 0.1 mm) than in the sham group (no marker separation). Craniometric data demonstrated the ability of the juvenile skull to distribute the change at the coronal suture throughout the skull to maintain symmetry and minimize disproportion. No distraction was obtained across the adult suture. In the juvenile suture distraction group without a period of stable fixation, a relapse of 17 +/- 6 percent was noted after 1 week, an additional 2.3 +/- 0.5 percent after the second week, and no further change in the third postdistraction week (n = 2; p < 0.01). These results show that in this animal model, distraction osteogenesis can be achieved across a growing cranial suture without an osteotomy or suturectomy and that the degree of distraction and new bone formation is comparable to that across an osteotomy. This suggests that cranial expansion can be obtained in a growing animal without using a more invasive cranial osteotomy. Additionally, the first week after distraction seems to be the most critical time period to maintain stable fixation.