Distraction Zone Research Articles

Ilizarov Distraction for Congenital Pseudoarthrosis of the Tibia in Adults.

The clinical evidence on the management for congenital pseudoarthrosis of the tibia (CPT) in adults is limited. The aim of this study is to assess the functional and radiological outcomes of Ilizarov distraction for treating CPT in adults. A retrospective analysis was conducted. Between 2013 and 2022, an Ilizarov distraction technique was performed on 14 adults (14 limbs) with CPT in our limb deformity center. There were seven females and seven males with a mean age of 33.7 (range, 18 ~ 53) years. The diagnosis of NF-1 was confirmed in seven (50.0%) patients. Eight patients had a history of previous surgical failure. The pseudoarthrosis occurred in the middle and lower tibia in all limbs (six left and eight right). The CPT was classified by Crawford classification and Paley classification. The surgical procedures, external fixation time (EFT), and all outcomes and complications were recorded. The Kolmogorov-Smirnov test was performed to test the normality of the data. The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score at the preoperative and final follow-up was compared by using the Wilcoxon's signed-rank test. The limb-length discrepancy (LLD) and a self-made exercise capacity score at the preoperative and final follow-up were compared by using the student's t-test. The clinical and radiological outcomes were assessed by the Inan scale. The mean EFT of Ilizarov fixator was 19.5 months (range, 7.3 ~ 39.1). At a median follow-up of 26.8 months (IQR, 20.2 ~ 34.3), bone union of the pseudarthrosis and consolidation of the distraction zone were achieved in all patients. The mean LLD was decreased from 11.3 cm (range, 3.4 ~ 17.3) preoperatively to 1.1 cm (range, 0.3 ~ 3.7) (p < 0.05). The mean or median AOFAS ankle-hindfoot score was improved from 53.5 (IQR, 26.5 ~ 60.5) preoperatively to 63.9 (range, 53 to 73) at final follow-up (p < 0.05). The mean score for exercise capacity were improved from 4.9 (range, 1 to 8) preoperatively to 9.6 (range, 7 ~ 12) at final follow-up (p < 0.05). According to the criteria described by Inan et al., the clinical results were classified as good in 10 and fair in 4, while the radiological results were classified as excellent in three, good in 8, and fair in 2. The success rate was 92.9%, as refracture was defined as treatment failure and occurred in one patient. Ilizarov distraction provided a suitable treatment option for the CPT in adults, as it could achieve a high rate of bone union, a good correction of secondary deformity, a low risk of refracture, and consequently restore a relatively functional limb.

Effect of transported segment size on the new bone formation of the rabbit femur in the Ilizarov bone transport method.

This study aimed to compare histological and radiological union in the bone transport of 3 segments of different sizes to reconstruct the rabbit femur's bone defects. Thirty rabbits were divided into 3 groups; a 1-cm defect was created in the femur in all rabbits. The length of the segment to be transferred was 10% of the femur length in group 1, 15% in group 2, and 20% in group 3. All defects were reconstructed by applying bone transport. At the end of the consolidation period, the distraction zone was compared radiologically and histologically. While there was no radiological difference between the groups, the highest histological scores were obtained from group 3. Osteocalcin staining revealed similar involvement in groups 2 and 3, butless involvement in group 1. Evidence from this study has shown that as the size of the segment used for bone transport increases, more stable fixation and better histological union tissue can be obtained in the rabbit femoral defect model.

The effect of shock waves on mineralization and regeneration of distraction zone in osteoporotic rabbits

Objective Osteoporotic individuals suffer from various complications such as spontaneous bone fractures due to decreased bone strength and failure in bone healing as a result of decreased bone mineral density and deterioration of bone microstructure. In this study, the effects of Extracorporeal Shock Wave Therapy (ESWT) in a distraction osteogenesis model in osteoporotic rabbits were investigated to prevent these failures and improve bone microstructure. Material and Methods A total of 28 female New Zealand rabbits underwent mandibular distraction osteogenesis and were divided into four groups: non-ovariectomized control (Cont), ovariectomized control (O-Cont), ovariectomized ESWT1 (O-ESWT1) and ovariectomized ESWT2 (O-ESWT2). ESWT was only applied to the ESWT2 group before the osteotomy, and to both the ESWT1 and ESWT2 groups after the osteotomy. Dual-energy x-ray absorptiometry was used to determine bone mineral density on both the 7th and 28th day of the consolidation. Stereological methods were used to identify new bone formation, connective tissue and neoangiogenesis volume. Results According to the dual-energy x-ray absorptiometry examination both at the 7th and 28th day of the consolidation, lower bone mineral density was seen in the ESWT groups. However, the stereological examination showed that shock wave therapy significantly increased new bone formation both ESWT1 and ESWT2 compared with O-Cont, significantly increased neoangiogenesis in O-ESWT1 compared with O-Cont. Conclusions The application of ESWT in these parameters after osteotomy was beneficial for bone regeneration in mandibular distraction in osteoporotics. However, ESWT has been shown to be ineffective in improving bone mineral density. KEY MESSAGES The osteoporotic model can be successfully established in rabbits and the subjects can tolerate the distraction procedures. Stereology is a useful analysis method that can determine the volume of the new bone formation and neoangiogenesis. Extracorporeal shock wave therapy has biostimulatory effects on bone tissue.

Distraction osteogenesis: Clinical applications and biologic principles for orthodontics and dentofacial orthopaedics

Dentofacial Distraction Osteogenesis is the gradual and incremental traction force/ tension to surgically separated bony segments of the stomatognathic system to produce additional bone with regeneration of attendant soft tissue. Distraction Osteogenesis/Histogenesis is a primary example of surgically induced tissue engineering. The distraction causes a cascade of biological factors to generate tissue (bone and soft tissue). It has become a substitute for current techniques of bone grafting and alloplastic materials in Dentofacial surgery. The principles of distraction osteogenesis can be simplified into 4 periods: 1. Creation of a distraction zone; 2. Latency period; 3. Activation period; 4. Consolidation period. The primary purpose of these principles is to shift the bony segment into the defect with regeneration of hard and soft tissues around the space of transported segment. There are 3 common types of distraction osteogenesis: unifocal, bifocal and trifocal depending upon number and direction of distraction devices employed and number of transport segments created. The process by which mechanical forces are converted to cellular signals is termed mechanical transduction. Through the conversion of mechanical (tension stress) signals to biological cascades, the DH method can activate a number of regulatory processes and restart the vigorous regenerating capacity of musculoskeletal tissues. The molecular mechanisms of DH are still expanding as a result of new technologies like next-generation sequencing, proteomics, and metabolomics, despite the fact that, any research have concentrated on them and the surgical concepts of DH have been better defined and perfected. This article explores types, histological stages, cellular and molecular mechanisms & indications.

Hypoxia During the Consolidation Phase of Distraction Osteogenesis Promotes Bone Regeneration.

BackgroundHypoxia is the critical driving force for angiogenesis and can trigger the osteogenic-angiogenic coupling followed by the enhancement of bone regeneration. While lots of studies showed that hypoxia administration can accelerate bone formation during distraction osteogenesis (DO), the therapeutic timing for the osteogenic purpose was concentrated on the distraction phase. The outcomes of hypoxia administration in the consolidation phase stay uncertain. The purpose of this study was to determine the osteogenic effectiveness of hypoxia therapy during the consolidation phase, if any, to enhance bone regeneration in a rat femoral DO model.MethodsA total of 42 adult male Sprague-Dawley rats underwent right femoral mid-diaphysis transverse osteotomy and were randomly divided into Control (NS administration, n = 21) and Group1 (deferoxamine therapy, n = 21) after distraction. During the consolidation phase, Group1 was treated with local deferoxamine (DFO) injection into the distraction zone, while the Control underwent the same dosage of NS. Animals were sacrificed after 2, 4, and 6 weeks of consolidation. The process of bone formation and remodeling was monitored by digital radiographs, and the regenerated bone was evaluated by micro-computed tomography (micro-CT), biomechanical test, and histological analysis. The serum content of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) were measured by enzyme linked immunosorbent assay (ELISA) for further analysis.ResultsBone regeneration was significantly enhanced after hypoxia therapy during the consolidation phase. The digital radiograph, micro-CT, and biomechanical evaluation showed better effects regarding volume, continuity, and mechanical properties of the regenerated bone in Group1. The histomorphological evaluation also revealed the hypoxia treatment contributed to accelerate bone formation and remodeling during DO. The higher positive expression of angiogenic and osteogenic markers were observed in Group1 after hypoxia administration according to the immunohistochemical analysis. The serum content of HIF-1α and VEGF was also increased after hypoxia therapy as evidenced from ELISA.ConclusionHypoxia administration during the consolidation phase of distraction osteogenesis has benefits in enhancing bone regeneration, including accelerates the bone formation and remodeling.

Effect of platelet-rich plasma on bone regenerate consolidation in distraction osteogenesis: An experimental study in rabbits.

The aim of this study was to determine the effect of platelet-rich plasma (PRP) on bone regenerate consolidation in a rabbit model of distraction osteogenesis. In this study, 12 male New Zealand rabbits weighing 1600 to 2000 g were used. All the rabbits were randomly divided into two groups (n = 6 per group): PRP group and control group. A two-ring, circular external fixator was applied to the right tibia of each rabbit in both groups. After corticotomy, all the tibiae were distracted at a rate of 0.5 mm/day for 20 days. PRP was injected to the osteotomy sites on the 7th, 14th, and 21st days postoperatively. Mineral density of the new bone tissue formed in the distraction zone was measured using quantitative computed tomography in the 3rd, 4th, and 5th weeks. At the end of the 6th week, the animals were sacrificed, and the specimens were evaluated biomechanically and histologically. Microcomputed tomography assessment showed significant bone mineral density increase from the 3rd to the 6th week (62.3% and 43.7% for the PRP and control groups, respectively). In the PRP group, the measurements on the 3rd, 4th, and 5th weeks were 416 ± 29, 487 ± 9.9, and 675 ± 37.8 HU (Hounsfield units), respectively, whereas in the control group were 313, 374, and 450 HU, respectively. In the comparison of weekly measurements of the two groups, the increase in bone density in the PRP group was higher than that in the control group (P < 0.001). During the mechanical tests, in the PRP group, the mean torsion was 46.50°and the mean torque 0.53 Nm, while in the control group, the mean torsion was 19.33°and the mean torque 0.65 Nm. The mechanical analysis of the groups revealed significant differences in the mean maximum torsion angles (P = 0.024). The histological examination showed that both groups had external and internal periosteal calli. Callus tissue in four rabbits in the PRP group and two rabbits in the control group was remodeled; normal bone formation occurred and distracted bone ends were completely healed. The results of the present study have indicated that PRP injection can enhance bone regenerate consolidation and increase bone mineral density during the healing process of distraction osteogenesis.

Sema3A accelerates bone formation during distraction osteogenesis in mice

ABSTRACT Distraction osteogenesis (DO) is a bone regeneration technique used to treat maxillofacial disorders, fracture nonunion, and large bone defects. It is well known for its amazing regenerative potential, but an extended consolidation period limits its clinical use. The interaction between the nervous system and bone regeneration has attracted great attention in recent years. Sema3A is a key axonal chemorepellent which has been proved to have bone-protective effects. In this article, we try to improve DO by local administration of Sema3A and explore the possible mechanisms. Forty wildtype, male, adult mice were divided into two groups after tibia osteotomy surgery. Sema3A or Saline was daily injected transcutaneous into the center of the distraction zone during the consolidation period. Micro-CT images were taken at 4, 6,8 and 10 weeks post-surgery; vascular density and biomechanical testing were performed at 10 weeks post-surgery. We also set up in vitro vessel growth assay to evaluate the effect of Sema3A on angiogenesis. Compared with the Saline group, Sema3A treatment significantly accelerated bone regeneration, improved angiogenesis and callus’ biomechanical strength. At 10 weeks post-surgery, compared with the Saline group, the BV/TV, BMD, TMD increased by about 23%, 22%, 18% respectively, vascular density increased by about 49% in the Sema3A group. Histological images and western-blot showed decreased expression of VEGF-A and increased expression of Ang-1 at 4 weeks post-surgery in the Sema3A group. In vitro, Sema3A suppressed VEGF-induced angiogenesis but had little effect on Ang-induced angiogenesis. Conclusion: Sema3A could accelerate bone regeneration and improve angiogenesis during DO.

Accelerated Bone Regeneration by Astragaloside IV through Stimulating the Coupling of Osteogenesis and Angiogenesis.

Both osteoblasts and preosteoclasts contribute to the coupling of osteogenesis and angiogenesis, regulating bone regeneration. Astragaloside IV (AS-IV), a glycoside of cycloartane-type triterpene derived from the Chinese herb Astragalus membranaceus, exhibits various biological activities, including stimulating angiogenesis and attenuating ischemic-hypoxic injury. However, the effects and underlying mechanisms of AS-IV in osteogenesis, osteoclastogenesis, and bone regeneration remain poorly understood. In the present study, we found that AS-IV treatment inhibited osteoclastogenesis, preserved preosteoclasts, and enhanced platelet-derived growth factor-BB (PDGF-BB)-induced angiogenesis. Additionally, AS-IV promoted cell viability, osteogenic differentiation, and angiogenic gene expression in bone marrow mesenchymal stem cells (BMSCs). The activation of AKT/GSK-3β/β-catenin signaling was found to contribute to the effects of AS-IV on osteoclastogenesis and osteogenesis. Furthermore, AS-IV accelerated bone regeneration during distraction osteogenesis (DO), as evidenced from the improved radiological and histological manifestations and biomechanical parameters, accompanied by enhanced angiogenesis within the distraction zone. In summary, AS-IV accelerates bone regeneration during DO, by enhancing osteogenesis and preosteoclast-induced angiogenesis simultaneously, partially through AKT/GSK-3β/β-catenin signaling. These findings reveal that AS-IV may serve as a potential bioactive molecule for promoting the coupling of osteogenesis and angiogenesis, and imply that AKT/GSK-3β/β-catenin signaling may be a promising therapeutic target for patients during DO treatment.

Effects of hyperbaric oxygen on the expression of osteoprotegerin and integrin β1 in rabbit＇s mandibular distraction gap

Objective To investigate the effect of hyperbaric-oxygen therapy on osteoprotegerin (OPG) and integrin β1 (Itgβ1) expression during mandibular distraction osteogenesis. Methods Forty New-Zealand rabbits were used. The animals were randomly divided into two groups (experimental group and control group) with 20 animals each; after accomplished osteotomy and implant distraction devices on mandible bilaterally for 3 days of latency period, the device was activated at the rate of 0.8 mm per day for 10 days. All animals in the experimental group were subjected to hyperbaric oxygen for 90 minutes once a day since the beginning of distraction, and lasted for four weeks. In control group, all the distractors were activated following the same distraction protocol as the experimental group, but without hyperbaric oxygen therapy. Five animals of each group were sacrificed at 10th day after distraction, 7th, 14th and 28th day of consolidation, respectively. The lengthened mandibles were harvested and processed for immunohistochemical examinations to detect OPG and Itgβ1 expression in the distraction gap. Semi-quantitative analysis was carried out by image analysis software. Results OPG staining was mainly located in the membrane and cytoplasm of osteoprogenitor cells and osteoblasts in the distraction zones. The expression of OPG increased after distraction accomplished and reached to the peak at 7th day of consolidation, and then decreased gradually. At every time point, the level of expression of OPG in the experimental group was remarkably higher than those in control group. There were significant differences between the experimental group and control group (P 0.05). Conclusions Hyperbaric oxygen therapy can up-regulate the expression of OPG and Itgβ1 in the distraction gap, which may promote osteoblast differentiation, proliferation, enhance osteoblast function, and new bone formation in distraction gap. Key words: Rabbits; Traction; Mandible; Integrin beta1; Osteoprotegerin; Hyperbaric-oxygen

Clinical research of extensive alveolar cleft treatment with computer assistant distraction osteogenesis

Objective: To evaluate the feasibility and outcome of computer assisted distraction osteogenesis in the treatment of extensive alveolar cleft. Methods: Four patients [1 male and 3 females, aged (15.5±3.7) years] received treatment in the Department of Oral-Maxillofacial Surgery and Plastic Surgery, School of Stomatology, China Medical University from June 2016 to April 2018 were involved in this study. All the patients with extensive alveolar cleft [cleft width (7.64±1.29) mm] were performed orthodontic treatment to expand the dental arch and interdental space between the first molar and premolars. Three-dimensional (3D) model of the maxilla and the osteotomy guider were printed according to the CT data. The fix wings of the distractor were pre-shaped according to the 3D model. The osteotomy was performed at the interdental space and horizontal plate of palate to dissociate the alveolar bone segment. The distractor was fixed on the predetermined position. Distraction (0.4-0.8 mm/day) was performed in 7 days later and stopped when the incision connected with the canine. The distractor was removed after six months. Results: The distraction period was (10.8±2.5) d in four cases. The cleft was completely closed with interdental bone anchored distraction in four cases. The imaging examination in six months showed good new bone structure in the distraction zone and bone connection of the cleft. Conclusions: Computer assisted distraction osteogenesis was effective and feasible to close the extensive alveolar cleft and provide sufficient new bone tissue.

The Effect of Different Doses of Extracorporeal Shock Waves on Experimental Model Mandibular Distraction.

Distraction osteogenesis (DO) is widely used treatment for the bone deformities. In addition extracorporeal shock wave therapy (ESWT) is a new perspective on noninvasive modalities of management of the bone regeneration. We examined the effects of 2 different single doses of ESWT on the consolidation period of DO of the rabbit mandible using stereological, radiological and immunohistochemical methods in the present study. DO was performed unilaterally in the mandible of 18 New Zealand rabbits (6 months' old, weighing between 2.5 and 3 kg). The distraction zone of the mandible has received no treatment as controls. Group 2 (ESWT 500) received ESWT (single dose of 500 impulses 0.19 mJ/mm energy flux intensity and 2155 mJ totally) were applied on the first day of the consolidation. Group 3 (ESWT 1000) treated with ESWT (single dose of 1000 impulses0.19 mJ/mm energy flux intensity and 4310 mJ totally) were applied on the first day of the consolidation period. After the sacrification, radiologically bone mineral density, new bone formation, new fibrous tissue, and new vessel formation were analyzed using unbiased stereological methods. It was found a statistically significant difference between the study groups and control group in the bone mineral density measurements and the highest values were in the ESWT1000 group. In terms of stereological analysis, there was a significant difference between the study groups and control group (P = 0.00). The new capillary volume was highest in the E1000 group. Additionally, significant differences were found in point of the capillary volumes between the groups control and ESWT500 (P = 0.001), control and ESWT1000 (P = 0.000), ESWT500 and ESWT1000 (P = 0.040), respectively. A total of 1000 impulses ESWT may induce the growth factors to enhance the newly formed bone regeneration.

Effects of Local Low-Dose Alendronate Injections Into the Distraction Gap on New Bone Formation and Distraction Rate on Distraction Osteogenesis.

Bisphosphonates that constrain bone resorption have a direct effect on osteoclast function. In this experimental study, the effects of low-dose local alendronate injections on the distraction gap (DG) in rabbit mandible at 2 different rates were evaluated.The experimental study was conducted on 20 male, New Zealand white rabbits. The animals were divided into 3 experimental groups and 1 control group. Group 1 consisted of animals with distraction at the rate of 1 mm/day, receiving postoperative local low-dose alendronate local injections into the DG. Group 2 consisted of animals with distraction at the rate of 2 mm/day, receiving postoperative 0.75 μg/kg of alendronate local injections into the DG. Group 3 consisted of animals with distraction at the rate of 2 mm/day, receiving postoperative 0.2 mL local saline injections into the DG. Group 4 consisted of animals with distraction at the rate of 1 mm/day, receiving postoperative 0.2 mL local saline injections into the DG. All the injections were performed immediately postoperatively and for all groups at 1, 2, 3, and 4 weeks following surgery. The distraction zones were evaluated using dual-energy X-ray absorptiometry and histological analysis.Histologically, bone healing was found to be significantly accelerated in Groups 1 and 4 compared with Groups 2 and 3 (P < 0.05). Bone healing was superior in Group 1 and the difference was statistically significant compared with Group 4. There was a significant increase in mean bone mineral density in the 1 mm daily rate groups (Groups 1 and 4) compared with the 2 mm daily rate groups (Groups 2 and 3) (P < 0.05).Local low-dose alendronate injections could be an effective way for improving bone formation in distraction osteogenesis. Furthermore, the results of this study did not support the hypothesis that injections of local low-dose alendronate may allow 2 mm/day instead of 1 mm/day of elongation in the rabbit mandible.

Reconstruction of large diaphyseal bone defect by simplified bone transport over nail technique: A 7-case series

Reconstruction of large diaphyseal bone defect is complex and the complications rate is high. This study aimed to assess a simplified technique of segmental bone transport by monorail external fixator over an intramedullary nail.A prospective study included 7 patients: 2 femoral and 5 tibial defects. Mean age was 31years (range: 16–61years). Mean follow-up was 62 months (range: 46–84months). Defects were post-traumatic, with a mean length of 7.2cm (range: 4 to 9.5cm). For 3 patients, reconstruction followed primary failure. In 4 cases, a covering flap was necessary. Transport used an external fixator guided by an intramedullary nail, at a rate of 1mm per day. One pin was implanted on either side of the distraction zone. The external fixator was removed 1 month after bone contact at the docking site. Mean bone transport time was 11 weeks (range: 7–15 weeks). Mean external fixation time was 5.1months (range: 3.5 to 8months). Full weight-bearing was allowed 5.7months (range: 3.5–13months) after initiation of transport. In one patient, a pin had to be repositioned. In 3 patients, the transported segment re-ascended after external fixatorablation, requiring repeat external fixation and resumption of transport. There was just 1 case of superficial pin infection. Reconstruction quality was considered “excellent” on the Paley-Marr criteria in 6 cases. The present technique provided excellent reconstruction quality in 6 of the 7 cases. External fixation time was shorter and resumption of weight-bearing earlier than with other reconstruction techniques, notably including bone autograft, vascularized bone graft or the induced membrane technique. Nailing facilitated control of limb axis and length. The complications rate was 50%, comparable to other techniques. This study raises the question of systematic internal fixation of the docking site, to avoid any mobilization of the transported segment. The bone quality, axial control and rapidity shown by the present technique make it well-adapted to reconstruction of diaphyseal bone defect. Level of evidenceFour-case series.

Intra-articular corrective osteotomies combined with the Ilizarov technique for the treatment of deformities of the knee

To present our experience of using a combination of intra-articular osteotomy and external fixation to treat different deformities of the knee. A total of six patients with a mean age of 26.5 years (15 to 50) with an abnormal hemi-joint line convergence angle (HJLCA) and mechanical axis deviation (MAD) were included. Elevation of a tibial hemiplateau or femoral condylar advancement was performed and limb lengthening with correction of residual deformity using a circular or monolateral Ilizarov frame. At a mean follow-up of 2.8 years (1.5 to 4.1), the mean HJLCA improved from 15.6° (10° to 23°) pre-operatively to 0.4° (0° to 2°). The mean MAD improved from 70.0 mm (20.1 to 118.5) pre-operatively to 9.1 mm (3 to 15). The mean tibiofemoral angle improved from 31.0° (8° to 54°) pre-operatively to 4.9° (2° to 8°). The mean limb-length discrepancy decreased from 6.3cm (2.9 to 13.6) pre-operatively to 1.1 cm (0 to 5). All osteotomies and distraction zones healed without complications. The use of intra-articular corrective osteotomies combined with the Ilizarov technique allowed correction of deformities of the knee joint with satisfactory HJLCA and overall mechanical axis in six patients with a good functional and cosmetic outcome in the short term. Cite this article: Bone Joint J 2017;99-B:204-10.

Is it possible to change of the duration of consolidation period in the distraction osteogenesis with the repetition of extracorporeal shock waves?

BackgroundIn this study we examined the effects of two different repeated Extracorporeal Shock Waves (ESW) on the consolidation period of the distraction osteogenesis (DO) of the rabbit mandible using stereological, radiological and immunohistochemical methods.Material and MethodsDO was performed unilaterally in the mandible of 18 New Zealand rabbits (six months old, weighing between 2.5-3 kg). In the consolidation period, rabbits were divided into three groups randomly after the distraction period. The distraction zone of the mandible was received no treatment as controls (E0*2). Group 2 (E 500*2) received ESWT (twice 500 impulses at 14 kV and 0.19 mJ/mm2 energy) in the first and fourth days of the consolidation. Group 3 (E1000*2) treated with ESWT (twice 1000 impulses at 14 kV and 0.19 mJ/mm2 energy) in the first and fourth days of the consolidation period. After the sacrification, radiologically bone mineral density, new bone formation, new fibrous tissue and new vessel formation were analyzed by stereological.ResultsIt was found a statistically significant difference between the study groups and control group in the bone mineral density measurements and the highest value was in the E1000*2 group. In the stereological analysis, new bone formation was highest in the E1000*2 group and there was a significant difference compared to the other groups (E0*2 and E500*2) (p=0.000). The lowest connective tissue volume was found in the E500*2 and there was a significant difference compared to the other groups (E0*2 and E1000*2) (p=0.000). The volume of the new vessel was highest in the E500*2 and lowest in the E0*2 group. It was found statistically significant difference between the values of the study and control groups.ConclusionsInterestingly, we found that repetition of the 1000 impulses ESWT accelerated the consolidation, 500 impulses ESWT extended consolidation period of the DO. Key words:Distraction osteogenesis, extracorporeal shock waves, stereology, rabbit.

Role of distraction osteogenesis in craniomaxillofacial surgery.

In the field of orthopedic surgery, distraction osteogenesis (DO) is well known for limb lengthening procedures or secondary corrective surgery in the fracture treatment of the extremities. The principle of gradual expansion of bone and surrounding soft tissues as originally described by G.A. Ilizarov is also applicable to the craniofacial skeleton when growth deficiency is present, and the patients affected by craniofacial or dentofacial anomalies may require distraction procedures. The surgical management is comparable. After osteotomy and the mounting of a specific craniomaxillofacial distraction device, active distraction is started after a latency phase of several days, with a distraction rate of up to 1 mm/day until the desired amount of distraction has been achieved. Subsequently, distractors are locked to provide appropriate stability within the distraction zone for callus mineralization during the consolidation phase of 3–6 months, which is followed by a further remodeling of the bony regenerate. After 14 years of clinical application, the role and significance of craniomaxillofacial DO are discussed after reviewing the files of all patients who were treated by craniomaxillofacial distraction procedures.

Total reconstruction of mandible by transport distraction after complete resection for benign and malignant tumors.

Distraction osteogenesis (DO) is a recognized technique for the bone lengthening and correction of various mandibular deformities. It has an aided advantage of both osteogenesis and histiogenesis in achieving a bone supported mandibular ridge covered with attached gingiva, forming an appropriate vestibule. The aim of this study was to present our clinical experience in using transport DO technique (TDO) for treating mandibular bony defects following tumor ablation in both benign and malignant tumor cases. This is a retrospective analysis of patients who underwent mandibular TDO for the correction of mandibular segmental defect at authors' center from 2000 to 2014 with the inclusion criteria of segmental bony defect in the mandible with moderate soft tissue defect. After the latency period of 10 days, the distraction was initiated at a rate of 0.25-1 mm/day. The distraction period continued until the segment with the transport disc reached the distal base. The total consolidation periods ranged from 6 to 14 weeks. The study group consists of 9 cases of TDO for reconstruction of segmental defect following tumor resection, of which 5 cases of benign and 4 cases of malignant tumor resection. The mean (standard deviation [SD]) bony defect length was 48 mm (9.8). The mean (SD) distracted bone lengthening was 43 mm (9.7), with a mean (SD) consolidation period of 17.9 (3.4) weeks. The bony defect involved the hemimandibular angle in four patients, hemimandibular body in three patients, with greater involvement of the body, symphysis in two patients, and of the bilateral mandibular body in two patients. Except for two patients who required additional bone grafting to complete union with the residual bone, other seven patients in the distraction zone showed the complete ossification by radiological evaluation. The mean (SD) consolidation period of 13.56 (1.5) weeks ranging from 12-15 weeks with the mean (SD) follow-up years is about 8.7 years (2.95) for the cases. Out of the 9 cases, one case had recurrence in the follow-up period and underwent resection with reconstruction using reconstruction plate in the created bone. The overall success rate of TDO was 88.9% (8 out of 9) in spite of adequate case selection and TDO protocol. TDO potentially benefits patients with segmental bony defects following tumor ablation in mandible. It is an unswerving tool to achieve sufficient bone in mandible in patients who cannot undergo aggressive surgery or poor general health. Bone resorption remains a critical issue for this reconstruction technique, though blood supply is continuously maintained in TDO.

Conditioned media from hypoxic-cultured human dental pulp cells promotes bone healing during distraction osteogenesis.

Distraction osteogenesis (DO) is a surgical procedure used to correct various skeletal disorders. Improving the technique by reducing the healing time would be of clinical relevance. The aim of this study was to determine the angiogenic and regenerative potential of conditioned media (CMs) collected from human dental pulp cells (hDPCs) grown under different culture conditions. CM collected from cells under hypoxia was used to improve bone healing and the DO procedure in vivo. The angiogenic potentials of CMs collected from hDPCs grown under normoxic (−Nor) and hypoxic (−Hyp) conditions were evaluated by quantitative PCR (VEGF‐A, angiopoietin‐1, angiopoietin‐2, interleukin‐6 (IL‐6) and CXCL12), ELISA assays (VEGF‐A, Ang‐2), tube‐formation and wound‐healing assays, using human umbilical vein endothelial cells. The results demonstrated that hypoxic CM had significantly higher angiogenic potential than normoxic CM. Human fetal osteoblasts (hFOBs) were exposed to CM, followed by alizarin red staining, to assess the osteogenic potential. It was found that CM did not enhance the mineralization capacity of hFOBs. DO was performed in the tibiae of 30 mice, followed by a local injection of 20 µl CM (CM–Nor and CM–Hyp groups) or serum‐free DMEM (control group) into the distraction zone every second day. The mice were sacrificed at days 13 and 27. The CM–Hyp treatment revealed a higher X‐ray density than the control group (p < 0.05). Our study suggests that the angiogenic effect promoted by hypoxic culture conditions is dependent on VEGF‐A and Ang‐2 released from hDPCs. Furthermore, CM–Hyp treatment may thus improve the DO procedure, accelerating bone healing. © 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.

Necessity of latency period in craniofacial distraction: Investigations with in vitro microdistractor and clinical outcomes

To determine the need for latency period in membranous bone distraction, we performed 1) in vitro comparison of preosteoblasts suspended in a 3D microdistraction model and 2) a clinical study comparing mandibular distraction cases with/without latency. In the In Vitro study, Preosteoblasts polymerized in 3D-collagen gel were placed in a microdistractor and separated into three groups: 1) distraction with latency, 2) distraction without latency, and 3) static. After 2, 4, 6, and 8 days, cell proliferation, total protein levels, alkaline phosphatase activity, and osteogenic gene expression were assessed through RT-PCR. In the clinical study, patients underwent mandibular distraction in two groups: 1) latency and 2) no latency (n = 45). The rest of the distraction protocol was identical. Outcome was based on clinical examination, radiographs at six months, and 3D CT scans. In the In Vitro study, The distraction without latency group compared to the latency group had delays in: proliferation, total protein count, alkaline phosphatase activity, osteogenic gene expression in CBFA-1 (fourfold vs. eighteenfold), and in osteocalcin (twofold vs. sixfold). The distraction without latency group had higher apoptotic levels during the first four days compared to the latency group (68% vs. 14%). For the clinical study, similar perioperative complications (5% vs. 6%), X-ray mineralization (93% vs. 94%), bone volume, (8.6 vs. 9.1 cc) and bone density of central distraction zone (78% vs. 81%) were observed with or without latency. In vitro studies showed poorer results in cell survival, proliferation and osteogenic activity compared to distraction with latency; yet, clinically, there were no differences in distraction with latency versus without.

Gene expression of osteogenic factors following gene therapy in mandibular lengthening.

This study investigated the effect of gene therapy on the expression of osteogenic mediators in mandibular distraction osteogenesis rabbits. Bilateral mandibular osteotomies were performed in 45 New-Zealand rabbits. After a latency of 3 days, the mandibles were elongated using distractors with a rate of 0.8 mm/d for 7 days. After the completion of distraction, the rabbits were randomly divided into 5 groups: 2 μg (0.1 μg/μL) of recombinant plasmid pIRES-hVEGF165-hBMP-2, recombinant plasmid pIRES-hBMP2, recombinant plasmid pIRES-hVEGF165, pIRES, and the same volume of normal saline were injected into the distraction gap of groups A, B, C, D, and E, respectively, followed by electroporation. Three animals were killed at the 7th, 14th, and 28th day after gene transfected in different groups, respectively. The lengthened mandibles were harvested and processed for immunohistochemical examinations; the mean optic densities (MODs) and integral optical density of bone morphogenetic protein (BMP-2) and transforming growth factor β1 (TGF-β1)-positive cells were measured by CMIAS-2001A computerized image analyzer. The data were analyzed with SPSS (SPSS Inc, Chicago, IL). Bone morphogenetic protein 2 and TGF-β1 staining was mainly located in inflammatory cells, monocytes, fibroblasts, osteoblasts, osteocytes, and chondrocytes in the distraction zones. Their strongest expression reached to the peak at the seventh day and decreased at the 14th day of consolidation stage; at the 28th day, they expressed weakly. Image analysis results show that, at the seventh day, the expression of BMP-2 in group B (0.26 ± 0.03, 0.36 ± 0.02) was the strongest; there was significant difference among them (P < 0.01), whereas the expression of TGF-β1 in group C (0.38 ± 0.06, 1.05 ± 0.19) is strongest followed by group A (0.34 ± 0.05, 0.95 ± 0.16) and B (0.33 ± 0.07, 0.90 ± 0.19). At every time point, the level of expression of BMP-2 and TGF-β1 in gene therapy groups (groups A, B, and C) was remarkably higher than those in non-gene therapy groups(groups D and E). There were significant differences between gene therapy groups and non-gene therapy groups (P < 0.05 or P < 0.001). These results indicated that local gene transfection can up-regulate the expression of osteogenic mediators (BMP-2 and TGF-β1), which may promote cell differentiation and proliferation and stimulate extracellular matrix synthesis and new bone formation in distraction gap.