Distraction Osteogenesis Technique Research Articles

Bone Regenerate Evaluation Methods.

Since its introduction by Ilizarov, the distraction osteogenesis technique has been used to treat trauma-related conditions, infections, bone tumors, and congenital diseases, either as methods of bone transport or elongation. One of the major dilemmas for the orthopedic surgeon who performs osteogenic distraction is establishing a reproducible method of assessing the progression of the osteogenesis, enabling the early detection of regenerate failures, in order to effectively interfere during treatment, and to determine the appropriate time to remove the external fixator. Several quantitative monitoring methods to evaluate the structural recovery and biomechanical properties of the bone regenerate at different stages, as well as the bone healing process, are under study. These methods can reveal data on bone metabolism, stiffness, bone mineral content, and bone mineral density. The present review comprehensively summarizes the most recent techniques to assess bone healing during osteogenic distraction, including conventional radiography and pixel values in digital radiology, ultrasonography, bone densitometry and scintigraphy, quantitative computed tomography, biomechanical evaluation, biochemical markers, and mathematical models. We believe it is crucial to know the different methods currently available, and we understand that using several monitoring methods simultaneously can be an ideal solution, pointing to a future direction in the follow-up of osteogenic distraction.

EXPERIENCE OF THE SEGMENTAL BONE DEFECTS' TREATMENT FOR PATIENTS WITH COMBAT TRAUMA USING THE METHOD OF DISTRACTION OSTEOGENESIS

Upper and lower limb injuries resulting from battlefield trauma is a complex multidisciplinary problem. Efficacy of the treatment of segmental bone defects in patients with combat trauma is a subject of analysis for improving its results. Purpose. An analysis of the modern treatment strategies of the segmental bone defects in patients with battlefield trauma under conditions of distraction osteogenesis (based on data available in the literature and own clinical experience). Methods. Analytical review of scientific works and analysis of treatment results of 39 patients with segmental bone defects associated with battlefield trauma and treated using distraction osteogenesis were conducted. Results. Patients with segmental limbs defects require special attention of a multidisciplinary team of specialists to identify reconstructive opportunities to save the limb. Distraction osteogenesis — is an effective method of treating of segmental fractures and shortening of the limbs, infectious complications that led to bone defect formation. Bone transport with ring external fixator (ExFix) is considered as a classical method. Authors analyzed and illustrated with three clinical cases their own results of application of different distraction osteogenesis technique. Conclusions. Different types of ExFix can be applied independently or in combination with internal fixators. The use of an intramedullar nail along which distraction osteogenesis is carried out allows to provide better control of the axis of the limb and transported fragment, reduce the residence time in the ExFix, and, moreover, external fixation devices with a simpler configuration can be used. Transport along the plate allows to maintain proper axial relationships in the presence of short periarticular fragments and improve the quality of fixation but it also increases the risks of FRI and re-operations.

Hemi one-piece distraction osteogenesis for unilateral coronal craniosynostosis

IntroductionIt was the aim of the study to assess the efficacy of the hemi one-piece distraction osteogenesis and to compare it to the traditional one-piece distraction osteogenesis technique. MethodsTwo different surgical techniques were used; the one-piece distraction and the hemi one-piece distraction. The principal distinction between the two techniques is that in the hemi style approach, the intact sutures on the contralateral side were left undisturbed, with no osteotomy performed. ResultsThe hemi one-piece group had a significantly lower median value of plastic surgery time, total operation time, and transfusion rate (plastic surgery time 69 min (range 65–120) vs. 20 min (range 17–32.5), p < 0.001; transfusion 80 mL (range 0–150) vs. 0 mL (0–60), p = 0.1. Nasofrontal advancement was successful with no major complications. Median endocranial angulation improved (one-piece: 166.1°–176.0°, hemi: 162.9°–173.0°, p = 0.023 & p = 0.012 respectively). ConclusionThis study reveals less invasive, highly effective techniques for craniosynostosis treatment, notably a unilateral osteotomy with distraction method. Nevertheless, to confirm their long-term efficacy and durability, more studies with longer follow-ups are essential.

Distraction osteogenesis versus induced membrane technique for infected tibial non-unions with segmental bone loss: a systematic review of the literature and meta-analysis of available studies.

Infected tibial non-unions with associated bone loss can be challenging to manage. At present, the two main methods utilized in the management of these fractures include the Ilizarov technique of Distraction Osteogenesis (DO) using external fixator devices, or alternatively, the Induced Membrane Technique (IMT), devised by Masquelet. As there is a paucity of data directly comparing the outcomes of these techniques, there is no universal agreement on which strategy a surgeon should choose to use. This systematic review and meta-analysis aimed to summarize the outcomes of both DO and IMT, in terms of primary outcomes (bone union and infection elimination), and secondary outcomes (complication rates and functional outcomes). A PRISMA strategy was used. Medline, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar library databases were interrogated using pre-defined MeSH terms and Boolean operators. Quality of evidence was evaluated using OCEBM and GRADE systems. Thirty-two studies with 1136 subjects met the inclusion criteria. With respect to the primary outcomes of interest, union was observed in 94.6% (DO method) and 88.0% (IMT method); this difference, however, was not significant between the two techniques (p = 0.45). In addition, infection elimination rates were also higher in the Ilizarov DO group when compared to Masquelet (Mq) IMT (93.0% vs 80.4% respectively). Again, no significant difference was observed (p = 0.06). For all secondary outcomes assessed (unplanned re-operations, re-fracture rates amputation rate), no statistically significant differences were documented between the treatment options. This study demonstrated that there is no clinical difference in outcomes for patients treated with Ilizarov DO versus Mq IMT techniques. The evidence base at present is relatively sparse and, therefore, we would recommend for further Level I studies to be conducted, to make more meaningful conclusions.

Management of Craniosynostosis in Lethal Perinatal Hypophosphatasia.

Although perinatal lethal hypophosphatasia (HPP) was once a disease with a universally poor prognosis, it has now become a rare but treatable condition with the advent of enzyme replacement therapy with asfotase alfa. As a result, a greater population of patients with perinatal HPP are presenting with abnormal head shape and craniosynostosis. The authors present here 3 cases of perinatal lethal HPP, 1 treated with traditional open cranial vault remodeling and 2 treated utilizing distraction osteogenesis techniques. All patients demonstrated outcomes comparable to those previously reported with traditional observation or open cranial vault repair. Thorough consideration and discussion between the surgical team and patient's family is needed to determine a treatment plan that best addresses the goals of patient and family in light of recent advances in medical treatment in this rare patient population in which surgical interventions were previously nearly impossible. This article further supports the safety and efficacy of surgical intervention and explores the utility of distraction osteogenesis to address craniosynostosis in this patient population.

Mono-Focal Distraction Osteogenesis in Management of Traumatic Bone Loss (Systematic Review of Literature)

Background Traumatic bone loss poses a serious problem for orthopedic surgeons added to the long standing risk of infection implied by open type fractures. Aim of the Work This study aims to assess the efficacy of distraction osteogenesis in compensating bone defects using the Paley score for functional and radiological outcomes. Methodology We searched the literature through PubMed database with publication date restricted to 10 years range from 2009-2019 English literature of prospective studies only were selected with strict inclusion criteria where repeated articles were excluded unless they presented follow up with functional outcome data about cases. Seven studies were included satisfying the predetermined inclusion criteria with total of 242 cases. Patients’ data were collected and analyzed with only: 176 cases mentioned demographic data with average age of ‘37’ and no comorbidities to decrease the risk of bias in our results. 125 patients had fractures in tibia without soft tissue loss and 51 patients needed skin grafting, 3.4% of total cases underwent late amputation, 14.2% experienced pin tract infection. Results Our results appear to demonstrate the efficacy of mono-focal distraction osteogenesis technique in compensating long bone defects of the lower limbs in traumatic events. We isolated studies reporting exclusively on either proximal tibia or distal tibia bone defects compared the respective outcomes of interest in the absence of statistical heterogeneity. The only significant difference that could be established was a four-fold decrease of the likelihood of fair functional results in the ‘distal tibia’ subgroup compared with the ‘proximal tibia’ subgroup. In distal tibial defects, we explored the impact of the size of a bone defect and duration of external fixation on outcomes of interest. We noticed a 3.7-times increase in the odds of re-fracture when the size of the distal tibial defect exceeded 8 cm Conclusion Mono-focal distraction osteogenesis (Ilizarov method) is effective in managing bone defects larger than 3 cm² however for defects larger than 8cm² there’s increased risk of re-fracture.

Role of Stem Cells in Transport Distraction Osteogenesis for Reconstruction of Mandibular Defects after Segmental Mandibulectomy

Purpose: to restore the continuity and functions of the mandible after segmental mandibulectomy for mandibular defect reconstruction by using a technique of transport distraction osteogenesis with stem cells injection. Subjects and methods: Clinical study was conducted on eight patients suffering from mandibular deficiency after tumor resection. All steps of manufacturing of the transport distractor, tumor resection and segmental mandibulectomy of transport disc were guided by Stereolithographic (STL) model. Stem cells sample was prepared to be injected along the soft callus at the end of the activation period. Patients were followed up postoperative clinically every week and radiographically by Panoramic x-ray and computed tomography (CT) at immediate postoperatively, then by panoramic x-ray monthly along the periods of distraction and finally by multi slice CT at the end of the consolidation to evaluate the time consuming for treatment. Results: seven cases out of eight cases recorded excellent distraction regenerate and excellent soft tissue coverage and one case out of these eight cases in the control group failed at the first week of activation. Multi slice CT showed a significantly higher value in the mean of the regenerated bone density at the end of the consolidation (1163.76±111.38) in the study group than the control group (747.67±268.6). Conclusion: From our study, stem cells injection in the distraction regenerate for reconstruction of mandibular defect cases achieved short consolidation period and high regenerated bone density.

Role of Stem Cells in Transport Distraction Osteogenesis for Reconstruction of Mandibular Defects after Segmental Mandibulectomy

Purpose: to restore the continuity and functions of the mandible after segmental mandibulectomy for mandibular defect reconstruction by using a technique of transport distraction osteogenesis with stem cells injection. Subjects and methods: Clinical study was conducted on eight patients suffering from mandibular deficiency after tumor resection. All steps of manufacturing of the transport distractor, tumor resection and segmental mandibulectomy of transport disc were guided by Stereolithographic (STL) model. Stem cells sample was prepared to be injected along the soft callus at the end of the activation period. Patients were followed up postoperative clinically every week and radiographically by Panoramic x-ray and computed tomography (CT) at immediate postoperatively, then by panoramic x-ray monthly along the periods of distraction and finally by multi slice CT at the end of the consolidation to evaluate the time consuming for treatment. Results: seven cases out of eight cases recorded excellent distraction regenerate and excellent soft tissue coverage and one case out of these eight cases in the control group failed at the first week of activation. Multi slice CT showed a significantly higher value in the mean of the regenerated bone density at the end of the consolidation (1163.76±111.38) in the study group than the control group (747.67±268.6). Conclusion: From our study, stem cells injection in the distraction regenerate for reconstruction of mandibular defect cases achieved short consolidation period and high regenerated bone density.

Application of 3D printed patient-specific instruments in the treatment of large tibial bone defects by the Ilizarov technique of distraction osteogenesis.

The Ilizarov technique of distraction osteogenesis is an effective treatment for tibia defect. However, repeated attempts to reduce due to the complexity of the bone defect during the operation will increase the operation time and iatrogenic injury, and excessive radiation exposure. Three-dimensional (3D)-printed patient-specific instrument (PSI) for preoperative 3D planning and intraoperative navigation have the advantages of accuracy and visualization. The purpose of this study is to investigate whether 3D-printed PSI is helpful to correct tibial bone defects accurately and effectively. From May 2019 to September 2022, 19 patients with tibial bone defects were treated, including 9 males and 10 females, aged 37 to 64 years. There were 4 cases in proximal tibia, 9 in midshaft tibia and 6 in distal tibia. All were treated with Ilizarov technique of distraction osteogenesis. 3D-printed PSI was used in 9 cases, while traditional surgery was used in 10 cases. All patients underwent computed tomography before surgery. Computer software was used to analyze the measurement results, design and print PSI. During the operation, PSI was used to assist in reduction of tibia. Operation times were recorded in all cases, the number of fluoroscopy during the operation, and the varus/valgus, anteversion/reversion angle after the operation were measured. All measurement data were expressed by means ± SD, and Student's t test was used to examine differences between groups. The chi square test or Fisher's precise test was used to compare the counting data of the two groups. All PSI matched well with the corresponding tibia bone defect, and were consistent with the preoperative plan and intraoperative operation. The affected limb had a good reduction effect. The operation time from the beginning of PSI installation to the completion of Ilizarov ring fixator installation was 31.33 ± 3.20 min, while that in the traditional operation group was 64.10 ± 6.14 min (p < 0.001). The times of fluoroscopy in the PSI group during operation was 10.11 ± 1.83, and that in the traditional operation group was 27.60 ± 5.82. The reduction effect of tibia in PSI group was better than that in traditional operation group, with the average angle of PSI group is 1.21 ± 0.24°, and that of traditional operation group is 2.36 ± 0.33° (p < 0.001). The PSI simplifies procedures, reduces the difficulty of the operation, improves the accuracy of the operation, and provides a good initial position when used in distraction osteogenesis to treat the tibial defects.

Anterior Maxillary Osteotomy Distraction Osteogenesis (Amodo) in the Treatment of Maxillary Hypoplasia in Unilateral Cleft Lip and Palate-A Case Report

Distraction osteogenesis defines a technique of bone generation by distraction of native bony segments. The technique offers a promising treatment alternative for patients with maxillary or midfacial hypolasia. In this case report, the various steps in the treatment of an 18 year old boy with premaxillary hypoplasia and anterior crossbite are described. Patient was treated with a distraction osteogenesis technique and premaxillary advancement was performed using individual tooth - borne distraction device. The surgical procedure involved an anterior segmental maxillary osteotomy respecting the palatal periosteum. Distractor was cemented in the mouth after the surgical procedures. The patient was observed during a seven day latency period after which the device was activated 0.4mm every 12 hours. The anterior crossbite was eliminated and the occlusal correction and settling was achieved with fixed orthodontic appliances.

Surgical bone augmentation procedures for oral rehabilitation of patients with oligodontia: A review with a systematic approach

Oligodontia is a developmental dental anomaly defined by the absence of 6 or more permanent teeth, excluding the third molars. We performed a review with a systematic approach and proposed a guideline for the choice of the bone augmentation surgery. The different bone augmentation technique terms were searched in the PubMed and Science Direct database. Clinical studies were eligible if they reported on pre-implant surgery in patients with oligodontia. The database search yielded 400 studies after duplicates removed. Thirty studies were finally included, involving 410 patients. Sixty-three sinus lifts were performed in 37 patients with no failure. Thirteen out of 33 patients with iliac bone transplantation and two out of 24 with parietal bone transplantation had resorption, one out of 4 patients who received allogeneic bone block had complete failure. Seventy-eight patients underwent guided bone regeneration, none had bone loss. No failure was found with the alveolar distraction osteogenesis technique. Four out of thirteen patients developed permanent hypoesthesia after inferior alveolar nerve transposition. The cumulative implant survival rate was 94.4% after bone augmentation procedures. Extensive edentulous areas should be grafted with parietal bone, as iliac grafts present a greater risk of resorption. Smaller edentulous areas should be treated by endobuccal harvesting or guided bone regeneration. Osteogenesis distraction and nerve transposition are effective surgeries for medium-to-large mandibular edentulous spaces. The implant survival rate is not significantly different between implants placed in grafted and nongrafted bone, the appropriate choice of bone augmentation technique can reduce the risk of peri‑implant bone resorption.

Rotation Advancement Distraction Osteogenesis Technique is Attributed to Unilateral Lambdoid Synostosis and is Used to Correct Posterior Plagiocephaly.

Unilateral lambdoid synostosis is the rarest form of craniosynostosis. Surgical correction is technically challenging from a morphological standpoint and is used to decompress intracranial pressure. Herein, the authors present a "rotational advancement bone flap" technique for the repair of posterior plagiocephaly. A bicoronal skin incision was performed, to expose the occipital region. The rotational advancement bone flap was designed to hinge off the nonsynostotic side, and it was set up to include an occipital protrusion on the normal side. On the premature side, an advancement bone flap was set up to include the flattened and deformed occipital bone. A titanium cranial distractor, which was attached between the bone flap and the anterior bone. An absorbable plate, which would later become a hinge due to the movement of the bone flap, was attached to the area for reinforcement. The authors technique was able to decompress intracranial pressure with satisfactory esthetic outcomes.

Two-Axis Continuous Distractor for Mandibular Reconstruction.

The application of Distraction Osteogenesis (DO) techniques in the reconstruction of skeletal deficiencies is a relatively new topic in the fields of oral and maxillofacial surgeries. In many reconstruction applications, using DO is the preferred technique, as opposed to conventional reconstruction techniques, as there are more advantages and fewer side effects when it is used. The first generation of DO devices is made up of manual distractors that can apply an intermittent distraction force to the bone segment during the distraction process. Manual DO techniques have shown the functionality of the DO technique. Further research has recently been performed on the development of automatic devices for generating a controlled continuous force. However, the existing automatic techniques have limitations, and are yet to be used in reconstruction applications in humans. There is still a gap between the developed techniques and an ideal distractor to be used in mandibular reconstruction surgeries. In this research, a two-axis continuous distractor is proposed for use in mandibular reconstruction applications. The proposed distractor can generate two continuous distraction forces that can be applied to two independent distraction vectors. The proposed device can perform the standard distraction process using the predetermined distraction factors. The control system has a high positioning accuracy and resolution in controlling the position of the intra-oral end effectors while applying two continuous forces for moving the bone segment. The proposed two-axis continuous distractor meets the current requirements, and can be used as an ideal continuous DO device for different mandibular reconstruction applications.

Use of Mandibular Distraction Osteogenesis to Correct Micrognathia and Airway Obstruction in Newborn Female with Pierre Robin Sequence and Neonatal Abstinence Syndrome in Rural Appalachia

We present a case of Pierre Robin sequence and Neonatal Abstinence Syndrome (NAS) in a newborn female patient to highlight the surgical technique of mandibular distraction osteogenesis to correct airway obstruction due to micrognathia. The patient presented as a transport after delivery due to respiratory distress. She was noted to have a cleft palate and micrognathia. The absence of other dysmorphic features diagnosed her with non-syndromic Pierre Robin sequence. To solve her upper airway obstruction, mandibular distraction osteogenesis was performed. This procedure allowed the patient to be weaned from all respiratory support and nasogastric tube feeds by the end of her hospitalization. She was able to be discharged home weeks before her internal hardware was surgically removed. Mandibular distraction osteogenesis was previously unavailable in rural Appalachia, making this case novel to the area. The patient also developed NAS during her hospitalization, highlighting the ongoing substance abuse epidemic in Appalachia.

Nine-year-long complex humeral nonunion salvaged by distraction osteogenesis technique: a case report and review of the literature

BackgroundHumeral nonunion with significant bone loss or shortening is uncommon and poses a complex clinical problem. We present a case of humeral nonunion with a large segmental bone defect treated with the distraction osteogenesis technique and remedy the radial nerve palsy produced during distraction osteogenesis by forearm tendon transfers. The reconstruction of upper limb function was achieved with satisfactory results. This case provides a referenceable alternative method for repairing large segmental bone defects due to complex nonunion of the upper extremity, as well as a remedy in the unfortunate event of radial nerve palsy, providing a reference and lessons learned for the treatment of similar cases and the management of possible complications.Case presentationA 31-year-old male patient experienced 9 years of hypertrophic nonunion due to an unreliable internal fixation. The radiographs showed the absence of bone bridging between the two fragments, loosening of the screws, and extensive osteolysis around the internal screws. The patient was treated with distraction osteogenesis. At the end of the distraction period, the patient unfortunately developed right radial nerve paresis, which was salvaged by forearm tendon transplantation, and finally reconstructed hand function and achieved bone union of the humerus.ConclusionDistraction osteogenesis, although not a panacea for all humeral nonunions with significant segmental bone loss, does offer a viable salvage procedure in this unusual and often complex clinical problem. When irreversible radial nerve palsy occurs during distraction, forearm tendon transfers can have a good clinical effect.

A new treatment strategy for hemifacial microsomia: Auricular reconstruction with an expanded two-flap method and simultaneous mandibular distraction osteogenesis

Owing to the complex clinical manifestations of hemifacial microsomia (HFM), multidisciplinary cooperation is required to achieve better therapeutic effects in terms of function and aesthetics. This study aimed to explore the efficacy of the expanded two-flap auricular reconstruction combined with mandibular distraction osteogenesis in the treatment of HFM. This surgical strategy was performed in three stages. In the first stage, the retroauricular skin was expanded with a tissue expander and a mandibular distraction device was installed. In the second stage, the traditional expanded two-flap method for auricular reconstruction was adapted, and the framework was fabricated with costal cartilage and wrapped with the expanded skin flap, retroauricular fascia flap, and full-thickness skin graft. In the final stage, the tragus and lobule were rebuilt, the concha cavity deepened, and the mandibular distraction device removed. From January 2014 to November 2018, 166 HFM patients underwent auricular reconstruction with the expanded two-flap method and simultaneous mandibular extension in our hospital. The median follow-up period was 9.3 months. Of the 166 patients, 154 patients and their families were satisfied with the results, and only 16 patients experienced complications. This three-stage technique of simultaneous auricular reconstruction and mandibular distraction osteogenesis is safe and effective in achieving facial symmetry, improving occlusal contact, shortening treatment course, and relieving patient's suffering, especially for HFM patients.

An Unoperated Crouzon Family Treated with Monobloc Distraction: Challenges and Lessons.

Background:Crouzon syndrome (CS) is a rare form of craniosynostosis characterized by bicoronal craniosynostosis and facial features including severe midface hypoplasia, exophthalmos, and hypertelorism. Most patients are diagnosed and treated in early childhood; however, there are a few reports of Crouzon patients treated as adults with monobloc facial advancement. To our knowledge, this is the first report of a family affected by CS treated sequentially with monobloc facial advancement using combined internal and external distraction osteogenesis (rigid external distraction).Methods:We present a family from Jamaica (mother 47 years old, older daughter 17, and younger daughter 9) who were brought to our craniofacial clinic with stigmata of CS and no previous surgical intervention. Patients had bicoronal craniosynostosis and exorbitism, with varying severity, sequelae, and comorbidities. Here, we delineate our technique of monobloc distraction osteogenesis with advancement osteotomies using dual “push–pull” method, elevation of a split anteriorly based tunneled pericranial flap to seal off nasal cavity, and internal and external distraction.Results:Our patients had favorable outcomes after reconstruction to reduce ocular symptoms and improve midface hypoplasia and aesthetic appearance. No intracranial injury, hardware/soft-tissue infection, hardware failure, or (new) loss of vision were encountered in 10 months follow-up.Conclusions:Dual “push–pull” monobloc distraction is safe and effective for a range of ages in CS; it allows good vector control, accommodates patient compliance, and allows early rigid external distraction device removal with sufficient time for consolidation. This surgery can be performed with highly satisfactory results.

Sutural fibroblasts exhibit the function of vascular endothelial cells upon mechanical strain

Midfacial hypoplasia is a type of facial dysplasia. The technique of trans-sutural distraction osteogenesis promotes midface growth so as to ameliorate this symptom. In the process of distraction osteogenesis, the fiber matrix in the suture acts as a mechanical sensor. Compared with osteogenesis, the formation of collagen fibers by fibroblasts is significant in the early stage of sutural distraction. However the transformation of fibroblasts during sutural bone formation induced by tensile force is poorly characterized. Here, we used single-cell RNA sequencing to define the cell classification of the zygomatic maxillary suture and the changes of cell clusters in the suture before and after seven-day distraction. We identified twenty-nine cell subsets spanning monocyte/macrophages, neutrophils, red blood cells, B cells and fibroblasts. Compared with the control group, Monocle analysis revealed the emergence of a unique fibroblast subset (Cdh5+, Col4a1+, Fat1−, and Acta2−) (cluster 27) that expressed vascular endothelial cell genes within the distracted zygomatic maxillary suture. We constructed the differentiation trajectories of the fibroblast population (cluster 23, 27) in the suture before and after distraction. In addition, we clarified that a subset of fibroblasts (cluster 27) lost expression of Fat1, an upregulator of the Hippo pathway, and upregulated Cyr61, a downstream gene of the Hippo pathway, during the distraction process. Further enrichment analysis suggests that cells of the new subset (cluster 27) are undergoing conversion of their identity into a vascular endothelial cell-like state in response to mechanical stimulation, associated with upregulation of angiogenesis genes along the single-cell trajectory. Further immunofluorescence staining confirmed this phenomenon. A combined general transcriptome RNA sequencing data analysis demonstrated that the fibroblasts expressed a number of extracellular matrix-related genes under mechanical strain. These data together provide a new view of the role of fibroblasts in tension-induced sutural angiogenesis via interaction with the Hippo pathway.

Polarized M2 macrophages induced by mechanical stretching modulate bone regeneration of the craniofacial suture for midfacial hypoplasia treatment.

The underlying mechanism of the trans-sutural distraction osteogenesis (TSDO) technique as an effective treatment that improves the symptoms of midfacial hypoplasia syndromes is not clearly understood. Increasing findings in the orthopedics field indicate that macrophages are mechanically sensitive and their phenotypes can respond to mechanical cues. However, how macrophages respond to mechanical stretching and consequently influence osteoblast differentiation of suture-derived stem cells (SuSCs) remains unclear, particularly during the TSDO process. In the present study, we established a TSDO rat model to determine whether and how macrophages were polarized in response to stretching and consequently affected bone regeneration of the suture frontal edge. Notably, after performing immunofluorescence, RNA-sequencing, and micro-computed tomography, it was demonstrated that macrophages are first recruited by various chemokines factors and polarized to the M2 phenotype upon optimal stretching. The latter in turn regulates SuSC activity and facilitates bone regeneration in sutures. Moreover, when the activated M2 macrophages were suppressed by pharmacological manipulation, new bone microarchitecture could rarely be detected under mechanical stretching and the expansion of the sutures was clear. Additionally, macrophages achieved M2 polarization in response to the optimal mechanical stretching (10%, 0.5Hz) and strongly facilitated SuSC osteogenic differentiation and human umbilical vein endothelial cell angiogenesis using an indirect co-culture system in vitro. Collectively, this study revealed the mechanical stimulation-immune response-bone regeneration axis and clarified at least in part how sutures achieve bone regeneration in response to mechanical force.

A Single-Center Retrospective Review of Perioperative Complications and Reoperation Rates Between Open Cranial Vault Remodeling and Distraction Osteogenesis for Unilateral Coronal Craniosynostosis.

Unilateral coronal craniosynostosis (UCS) is the third most prevalent form of craniosynostosis. Traditional treatment of UCS has been achieved with fronto-orbital advancement and cranial vault remodeling (FOAR), but utilization of cranial distraction osteogenesis (DO) techniques has increased. This study aims to compare perioperative complications and reoperation trends in FOAR versus DO techniques at a single institution. An Institutional Review Board-approved retrospective review was performed from January 1999 to November 2018 at a single institution. Patients were those that have undergone FOAR or DO with an anterior rotational flap technique as previously described. Indications for secondary procedures included: contour deformities, relapse, surgical site infection, and persistent cranial defects. Eighty-one patients with UCS were identified, 64 patients underwent FOAR and 17 patients underwent DO. When perioperative characteristics were compared, patients who underwent DO were younger in age, however, there was no significant difference in transfusion requirement or length of stay between patient cohorts. Surgery time was increased in DO patients. When perioperative complications were compared, more intraoperative dural tears were observed in the FOAR cohort. When unplanned reoperation rates were compared, patients who had undergone FOAR had a statistically significant higher reoperation rates at 5 years of follow up. When including routine distractor removal as a reoperation, reoperative rate was increased in the DO cohort. No difference in reoperation rates was noted at 5 years following index operation. The safety profile of DO is similar to that of traditional FOAR techniques for treatment of UCS. Longer-term follow-up studies are needed to elucidate whether outcomes are durable, but the unplanned reoperation rate in DO is less than that of FOAR at 5 years and presents several advantages that warrants its use in patients with UCS.