Reconstruction of large mandibular bone and soft-tissue defect using bone transport distraction osteogenesis

Cranial Bone Transport Promotes Angiogenesis, Neurogenesis, and Modulates Meningeal Lymphatic Function in Middle Cerebral Artery Occlusion Rats

BACKGROUND

Ischemic stroke is a leading cause of death and disability worldwide. However, the time window for quickly dissolving clots and restoring cerebral blood flow, using tissue plasminogen activator treatment is rather limited, resulting in many patients experiencing long-term functional impairments if not death. This study aims to determine the roles of cranial bone transport (CBT), a novel, effective, and simple surgical technique, in the recovery of ischemic stroke using middle cerebral artery occlusion (MCAO) rat model.

METHODS

CBT was performed by slowly sliding a bone segment in skull with a special frame and a speed of 0.25 mm/12 hours for 10 days following MCAO. Morris water maze, rotarod test, and catwalk gait analysis were used to study the neurological behaviors, and infarct area and cerebral flow were evaluated during CBT process. Immunofluorescence staining of CD31 and Nestin/Sox2 (sex determining region Y box 2) was performed to study the angiogenesis and neurogenesis. OVA-A647 (ovalbumin-Alexa Fluor 647) was intracisterna magna injected to evaluate the meningeal lymphatic drainage function.

RESULTS

CBT treatment has significantly reduced the ischemic lesions areas and improved the neurological deficits in MCAO rats compared with the rats in the control groups. CBT treatment significantly promoted angiogenesis and neurogenesis in the brain of MCAO rats. The drainage function of meningeal lymphatic vessels in MCAO rats was significantly impaired compared with normal rats. Ablation of meningeal lymphatic drainage led to increased neuroinflammation and aggravated neurological deficits and ischemic injury in MCAO rats. CBT treatment significantly improved the meningeal lymphatic drainage function and alleviated T-cell infiltration in MCAO rats.

CONCLUSIONS

This study provided evidence for the possible mechanisms on how CBT attenuates ischemic stroke injury and facilitates rapid neuronal function recovery, suggesting that CBT may be an alternative treatment strategy for managing ischemic stroke.

Reconstruction of Mandibular Segmental Detects Using Transport Disk Distraction Osteogenesis

BACKGROUND

Distraction osteogenesis (DO) has become an important alternative for bone defect reconstruction. The study aims to investigate the clinical feasibility and efficiency of transport disc DO (TDDO) for reconstruction of segmental defect of mandible and further dental implant treatment.

METHODS

A serial of 6 patients diagnosed with ameloblastoma or keratocystic odontogenic tumor were included in this study. Computed tomography (CT) scanning and panoramic radiograph were performed for preoperative evaluation and surgery planning. Transport disc DO was applied simultaneously with tumor resection for reconstruction of mandibular defects. The postoperative panoramic radiographs and CT scans were taken for evaluation of the ossification level. Then a second surgery was performed for removal of the distraction apparatus. Bone graft and rigid internal fixation were also used to fill the gap between the transport disc and the stump of the residual ramus. Further dental implant treatment was also finished or in progress.

RESULTS

All patients finished the whole treatment period, and no distraction device failure or tumor recurrence occurred. The distraction length ranged from 35 to 48 mm and the whole treatment period of TDDO ranged from 21 to 33 weeks. High degree of ossification was confirmed at the end of treatment by postoperative radiographs and intraoperative observation. Infection occurred in 1 of the 6 patients, and the symptom was controlled by surgical dressing change and flushing. Results of final facial profile in all patients were good. Three patients finished dental implant treatment with good occlusion.

CONCLUSION

Results in this study suggest the clinical feasibility and efficiency of TDDO for reconstruction of segmental defect of mandible and further dental implant treatment.

Is Distraction Osteogenesis of the Irradiated Craniofacial Skeleton Contraindicated?

BACKGROUND

Craniofacial distraction osteogenesis (DO) is a common treatment modality today. Despite its numerous advantages, however, concerns have been expressed regarding the use of DO in the irradiated setting.

METHODS

A systematic review was performed to identify all published reports of patients who underwent DO of the irradiated craniofacial skeleton. The following parameters were of particular interest: postoperative complications, specifically, insufficient bone formation, fracture, and hardware exposure (intraoral and cutaneous), as well as the need for additional bone grafting.

RESULTS

The initial search retrieved a total of 183 articles of which 20 articles (38 patients) met predetermined inclusion criteria. The most common site of distraction was the mandible (76.3%). The median radiation dose was 50.7 Gy (range, 30-70 Gy). Bone defects ranged from 30 to 80 mm (median, 42.5 mm). Complications were encountered in 19 patients (50%), with insufficient bone formation being most common (9 patients; 23%). The overall incidence of complications was not significantly associated with radiation dosage (P = 0.79). The remaining procedural and demographic variables also failed to meet statistical significance when compared against the overall complication rate (P = 0.27-0.97).

CONCLUSION

The complication rate associated with craniofacial DO of the irradiated skeleton does not appear to be substantially higher than what is reported for DO in the nonirradiated setting. As such, patients should be offered this treatment modality, particularly in light of the fact, that it offers the option to decrease patient morbidity as well as treatment complexity.

Nonvascularized Free Transport Distraction Osteogenesis to Reconstruct the Mandibular Defect of a Patient With an Ossifying Fibroma: A Case Report

We report on a case in which trifocal distraction osteogenesis was applied in a patient with a mandibular defect caused by resection of an ossifying fibroma. During the surgical procedure, we accidentally dissected the surrounding periosteal tissue of the left transport completely in the process of transport disc preparation and made the disc into a free bone graft. However, we still used this transport and successfully completed the distraction osteogenesis. The patient's facial and occlusal function were regained after treatment.

Distraction histogenesis of the maxillofacial region

The changes in the surrounding soft tissues during long bone distraction in orthopedic surgery have been the subject of several reports, studies on changes in the craniofacial region, in which various tissues, including the skin, muscle, tendon, blood vessel, and gingiva are rare. Therefore, there is a need for studies on the soft tissue aspects of bone lengthening of the craniofacial region. The aim of this review was to address this issue by reviewing the literature about the distraction histogenesis of various tissues, including skin, muscle, blood vessel, nerve, and gingiva.

Dentate transport discs can be used to reconstruct large segmental mandibular defects

PURPOSE

This study tested the use of a dentate transport segment for the reconstruction of a large U-shaped defect in the anterior segment of the canine mandible using a novel curved reconstruction plate. The quality and quantity of bone regenerate formed by dentate versus edentulous transport segments were compared.

MATERIALS AND METHODS

In 5 adult foxhound dogs, a defect of 70 to 75 mm was created in the canine mandible by excising the mandible anterior to the right and left fourth premolars. Reconstruction was performed by trifocal distraction osteogenesis using a bone transport reconstruction plate (BTRP-02), with 2 transport units being activated simultaneously, one on either side of the defect, 1 dentate and 1 edentulous. Bilateral distraction proceeded at a rate of 1 mm/day until the segments docked against each other in the midline. After 39 to 44 days of consolidation, the animals were euthanized. The quantity and quality of bone regeneration on the 2 sides were compared using micro-computed tomography.

RESULTS

The defect reconstruction was successful. The amount and quality of bone formed by the transport segments were similar on the 2 sides. There were no major differences in the bone volume fraction and density of the regenerate bone formed by the 2 transport segments. The bone volume fraction and density of the regenerate bone were considerably lower than those of the host bone in the distal segments, likely owing to the short consolidation period.

CONCLUSIONS

Bone transport remains a viable option in reconstructing anterior segmental defects in the mandible. The use of dentate or edentulous transport segments for reconstruction provides options for the surgeon in often highly compromised patients requiring these surgeries.

Alveolar ridge augmentation for implant fixation: status review

This literature review was performed to illustrate and compare different alveolar ridge augmentation procedures before dental implant placement. The review was based on clinical and research studies listed in Pubmed. There is not enough evidence to support any single method as gold standard for any given condition, and choice seemed to be based on personal preferences. There is a lack of long-term survival data or success rates of grafting materials regarding donor and recipient sites. Although ridge splitting and distraction osteogenesis techniques eliminate donor site morbidity, circumvent the use of grafting materials, and reduce the operation time, some disadvantages and limitations should be considered. More studies are needed to compare the fate and characteristics of new bone obtained by these different procedures, as well as subsequent implant survival rates.

Restoration of critical-size defects in the rabbit mandible using porous nanohydroxyapatite-polyamide scaffolds

Composite nanohydroxyapatite/polyamide (n-HA/PA) biomaterials have been indicated for bone defect reconstruction, where PA is added to enhance the toughness of n-HA. However, a comprehensive understanding of the biological performance of this implant material remains to be determined. In this study, the biological activity of n-HA/PA biomaterials was characterized in vitro by assessing the growth of bone marrow stromal cells (BMSCs), and in an in vivo rabbit model. To evaluate the n-HA/PA performance under different osteogenic conditions in vivo, implants were inserted to critical-size bone defects in the angle and body of the rabbit mandible. To determine the necessity of ectogenic BMSC-n-HA/PA hybrids at different implantation sites, both raw n-HA/PA materials and BMSC-seeded n-HA/PA hybrids were implanted. Bone formation was detected by radiology and histological studies. The results showed that n-HA/PA composites had great bioactivity, demonstrating significant BMSC proliferation, active alkaline phosphatase secretion, and stimulating the expression of osteogenic proteins (bone morphogenetic protein 2 [BMP2], osteoprotegerin [OPG], osteopontin [OPN], collagen type I [Col I], and osteocalcin [OCN]), in comparison to the control (polyethylene). At marrow-rich implantation sites (mandibular body), the amount of new bone formation was significant, but was not enhanced by the presence of BMSCs in the BMSC-n-HA/PA hybrids. However, the BMSC-n-HA/PA hybrids were essential for promoting bone formation in marrow-poor sites (mandibular angle). In conclusion, n-HA/PA biomaterials, which offer the advantage of enhanced mechanical performance over n-HA, exhibit significant bioactivity, including the capacity for bone regeneration at marrow-poor sites when implanted in combination with BMSCs.

Three-dimensional evaluation of mandibular bone regenerated by bone transport distraction osteogenesis

The purpose of this study was to evaluate the structure and material properties of native mandibular bone and those of early regenerate bone, produced by bone transport distraction osteogenesis. Ten adult foxhounds were divided into two groups of five animals each. In all animals, a 3- to 4-cm defect was created on one side of the mandible. A bone transport reconstruction plate, consisting of a reconstruction plate with an attached intraoral transport unit, was utilized to stabilize the mandible and regenerate bone at a rate of 1 mm/day. After the distraction period was finished, the animals were killed at 6 and 12 weeks of consolidation. Micro-computed tomography was used to assess the morphometric and structural indices of regenerate bone and matching bone from the unoperated contralateral side. Significant new bone was formed within the defect in the 6- and 12-week groups. Significant differences (P ≤ 0.05) between mandibular regenerated and native bone were found in regard to bone volume fraction, mineral density, bone surface ratio, trabecular thickness, trabecular separation, and connectivity density, which increased from 12 to 18 weeks of consolidation. We showed that regenerated bone is still mineralizing and that native bone appears denser because of a thick outer layer of cortical bone that is not yet formed in the regenerate. However, the regenerate showed a significantly higher number of thicker trabeculae.

Bone regeneration and docking site healing after bone transport distraction osteogenesis in the canine mandible

PURPOSE

Bone transport distraction osteogenesis provides a promising alternative to traditional grafting techniques. However, existing bone transport distraction osteogenesis devices have many limitations. The purpose of this research was to test a new device, the mandibular bone transport reconstruction plate, in an animal model with comparable mandible size to humans and to histologically and mechanically examine the regenerate bone.

MATERIALS AND METHODS

Eleven adult foxhounds were divided into an unreconstructed control group of 5 animals and an experimental group of 6 animals. In each animal, a 34-mm segmental defect was created in the mandible. The defect was reconstructed with a bone transport reconstruction plate. Histologic and biomechanical characteristics of the regenerate and unrepaired defect were analyzed and compared with bone on the contralateral side of the mandible after 4 weeks of consolidation.

RESULTS

The reconstructed defect was bridged with new bone, with little bone in the control defect. Regenerate density and microhardness were 22.3% and 42.6%, respectively, lower than the contralateral normal bone. Likewise, the anisotropy of the experimental group was statistically lower than in the contralateral bone. Half the experimental animals showed nonunion at the docking site.

CONCLUSION

The device was very stable and easy to install and activate. After 1 month of consolidation, the defect was bridged with new bone, with evidence of active bone formation. Regenerate bone was less mature than the control bone. Studies are underway to identify when the regenerate properties compare with normal bone and to identify methods to augment bone union at the docking site.

Two-step transport-disk distraction osteogenesis in reconstruction of mandibular defect involving body and ramus

One-step transport-disk distraction osteogenesis (TDDO) is effective for repairing segmental mandibular defects. The authors studied whether it was effective for reconstructing angled large mandibular defects using a two-step TDDO procedure in seven patients suffering from neoplasm. In the two-step TDDO procedure, the first distraction (horizontal distraction) was initiated immediately after mandibulectomy, aimed at restoring the mandibular body. It was followed by the second distraction, which was obliquely vertical and aimed at restoring the height of the ramus. The distraction rate was set at twice 0.4mm/day. The treatment lasted for 14-18 months. The horizontal distraction length ranged from 48 to 55mm, and the vertical one from 33 to 43mm, with full ossification in the distraction area. No obvious shift of mandible, malocclusion or mouth opening limitation was observed. Patients had a regular diet and spoke clearly. In conclusion, the two-step TDDO is still an option for the reconstruction of large angled mandibular defects when patients are prudently selected, despite the long treatment period required.

Reconstruction of canine mandibular bone defects using a bone transport reconstruction plate

OBJECTIVES

Reconstruction of mandibular segmental bone defects is a challenging task. This study tests a new device used for reconstructing mandibular defects based on the principle of bone transport distraction osteogenesis.

METHODS

Thirteen beagle dogs were divided into control and experimental groups. In all animals, a 3-cm defect was created on one side of the mandible. In 8 control animals, the defect was stabilized with a reconstruction plate without further reconstruction and the animals were killed 2 to 3 months after surgery. The remaining 5 animals were reconstructed with a bone transport reconstruction plate, comprising a reconstruction plate with attached intraoral transport unit, and were killed after 1 month of consolidation.

RESULTS

Clinical evaluation, cone-beam CT densitometry, three-dimensional histomorphometry, and docking site histology revealed significant new bone formation within the defect in the distracted group.

CONCLUSION

The physical dimensions and architectural parameters of the new bone were comparable to the contralateral normal bone. Bone union at the docking site remains a problem.