Determination of mandibular distraction osteogenesis most suitable parameters. An experimental study.

BACKGROUND: Distraction osteogenesis is a process of induced bone generation. Various protocols have been described for the management of the latency period, distraction speed and consolidation period, with greater or lesser success. OBJECTIVE: To better understand the process of mandibular distraction and establish the determining factors and their optimal times. MATERIAL AND METHODS: Twenty-seven dogs were studied, which had 54 distractors placed and that underwent unidirectional, bilateral mandibular distraction osteogenesis. The distraction processes were applied using six variants, two for each factor: latency period, distraction period and distraction speed. The changes were examined by means of bone biopsies and X-rays of the area at 0, 7, 14, 21, 45 and 55 days of the process. RESULTS: The most efficient osteogenic distraction parameters were a latency period of five days, a consolidation period of six weeks, distraction speed of 1 mm/day for distances of less than 20 mm, and 3 mm/day for longer distances. CONCLUSIONS: The sequential histological study allowed to observe the appearance of cellular elements (osteocytes, osteoclasts, osteoid matrix, trabeculate, etc.) and their participation in granulation tissue, newly-formed bone and compact mature bone.

ANTECEDENTES: Respecto a la distracción osteogénica (generación ósea inducida), con mayor o menor éxito han sido descritos diversos protocolos para el manejo del período de latencia, velocidad de distracción y período de consolidación. ­. OBJETIVO: Entender mejor el proceso de la distracción mandibular y establecer los factores determinantes y sus tiempos óptimos. MATERIAL Y MÉTODOS: Se estudiaron 27 perros sometidos a distracción osteogénica unidireccional, bilateral de la mandíbula. Los procesos de distracción se aplicaron con seis variantes, dos por cada factor (período de latencia, período de distracción y velocidad de distracción). Se estudiaron los cambios mediante biopsias del hueso y radiografías de la zona a los 0, 7, 14, 21, 45 y 55 días del proceso. RESULTADOS: Los parámetros de distracción osteogénica más eficientes fueron período de latencia de cinco días, período de consolidación de seis semanas, 1 mm diario de velocidad de distracción para distancias menores a 20 mm y 3 mm diarios para distancias mayores. CONCLUSIONES: El estudio histológico secuencial permitió observar la aparición de los elementos celulares (osteocitos, osteoclastos, matriz osteoide, trabeculado, etcétera) y su participación en el tejido de granulación, el hueso neoformado y el hueso maduro compacto.

Alternated activation with relaxation of periosteum stimulates bone modeling and remodeling.

Gradual elevation of the periosteum from the original bone surface, based on the principle of distraction osteogenesis, induces endogenous hard and soft tissue formation. This study aimed to assess the impact of alternating protocols of activation with relaxation (periosteal pumping) on bone modeling and remodeling. One hundred and sixty-two adult male Wistar rats were used in this study. Four test groups with different pumping protocols were created based on the relaxation applied. Two control groups underwent an activation period without relaxation or only a single activation. One group was sham-operated. Periosteal pumping without period of activation induced gene expression in bone and bone remodeling, and following activation period enhanced bone modeling. Four test groups and control group with activation period equaled the values of bone modeling at the end-consolidation period, showing significant downregulation of Sost in the bone and periosteum compared to that in the sham group (p < 0.001 and p < 0.001, respectively). When all test groups were pooled together, plate elevation from the bony surface increased bone remodeling on day 45 of the observation period (p = 0.003). Furthermore, bone modeling was significantly affected by plate elevation on days 17 and 45 (p = 0.047 and p = 0.005, respectively) and by pumping protocol on day 31 (p = 0.042). Periosteal pumping was beneficial for increasing bone repair when the periosteum remained in contact with the underlaying bony surface during the manipulation period. Following periosteal elevation, periosteal pumping accelerated bone formation from the bony surface by the modeling process.

Impact of upper airway obstruction management in Robin Sequence on need for myringotomy tubes.

OBJECTIVE: Investigate an association between upper airway obstruction (UAO) management in Robin Sequence (RS) and need for bilateral myringotomy and tubes (BMT). METHODS: Retrospective chart review of RS patients treated at a tertiary free-standing pediatric hospital from 1995 to 2020 was performed. Patients were grouped based on airway management: conservative, tracheostomy, tongue-lip adhesion (TLA), and mandibular distraction osteogenesis (MDO). Demographic data, cleft palate (CP) association, numbers of BMT and ear infections, and audiogram data including tympanograms were collected. One-way ANOVA and Chi-square/Fisher's exact tests were used to compare continuous and categorical data, respectively. Multivariable regression analysis was used to compare BMT rates between treatment groups. RESULTS: One hundred forty-eight patients were included, 70.3 % of which had CP. Most patients (67.6 %) had at least one BMT; 29.1 % required two or more BMT. The rate of BMT was higher in patients with CP compared to those with intact palates (p = 0.003; 95 % CI 1.30-3.57) and those treated with tracheostomy (p = 0.043; 95 % CI 1.01, 2.27). Surgically managed patients were more likely to have hearing loss (67.5 % vs. 35.3 %, p = 0.017) and ear infections (42.1 % vs. 20.0 %, p = 0.014) pre-compared to post-procedure for airway management. CONCLUSION: Most RS patients require at least 1 set of BMT. Those with CP and/or treated with tracheostomy had a higher likelihood of needing BMT. Rate of hearing loss and ear infection was higher in surgically managed RS patients. Patients with RS and overt CP require a statistically higher number of BMTs compared to those with either submucous cleft palate or intact palate.

Semi-focal bone transport versus traditional bone transport technique for the management of large tibial bone defects after trauma.

How to deal with large tibial bone defects is still controversial. The purpose of this research was to compare the semi-focal bone transport (SFBT) technique with traditional bone transport (TBT) technique for treating such patients. Sixty-two patients were included and retrospectively analyzed. In all cases, after radical debridement large tibial bone defects remained. Patients were treated by the SFBT or TBT technique. The distraction, consolidation duration and complications were recorded by the patients' medical files. Based on the Association for the Study and Application of Methods of Ilizarov (ASAMI) standard, the bone and functional results were evaluated. The mean bone defect size was 7.7 ± 1.6 cm and 7.5 ± 2.1 cm for SFBT and TBT patients. The mean external fixation index (EFI) was 1.51 ± 0.14 months/cm and 1.89 ± 0.25 months/cm for SFBT and TBT patients (p < 0.05), respectively. With respect to bone and function results, there was no significant differences between the two groups (p > 0.05). The mean number of complications per patient was 1.1 ± 0.6 and 1.6 ± 0.7 for SFBT and TBT patients (p < 0.05). Compared to the traditional bone transport technique, patients using the semi-focal bone transport technique achieved better clinical effects, including shorter EFI and less complications. Therefore, the SFBT technique could be a new option for patients with large tibial bone defects.

Metatarsal lengthening by distraction osteogenesis for brachymetatarsia in paediatric patients: is it safe and effective?

PURPOSE: The primary aim is to assess the efficacy of the surgical callus distraction technique of the metatarsus in paediatric patients. Secondary objectives are to assess complications and treatment duration. We have also described the details of our surgical technique. MATERIALS AND METHODS: A case series review of paediatric patients who had metatarsal lengthening at our unit between 2014 and 2022. Patient demographics, duration of time in frame, complications and metatarsal length achieved were recorded. The AOFAS Midfoot and the MOXFQ were taken pre-operatively and at final follow-up. RESULTS: Sixteen metatarsals in 8 patients (14 feet) underwent lengthening between 2014 and 2022 using the MiniRail OrthoFix 100 (Orthofix Medical Inc, Lewisville, TX, USA). The mean age was 13.3 (12-17) years. The average duration between surgery and implant removal was 5.2 months. According to Paley's classification, there was one obstacle encountered in a patient who required a revision of their osteotomy and one problem in another patient who had an infected metatarsophalangeal joint stabilising k-wire treated with oral antibiotics. The Mean AOFAS Midfoot score improved from 53.10 to 86.40 (p < 0.0001) and the Mean MOXFQ improved from 32.5000 to 12.1250 (p < 0.05); these were statistically significant. CONCLUSION: Gradual metatarsal lengthening using the MiniRail external fixator is a safe and effective method to treat brachymetatarsia in paediatric patients. This preliminary report describes and supports metatarsal lengthening in appropriate patients. Holistic care in terms of a pre-operative assessment, psychological support and preparation for the extended rehabilitation period are vital.

The Role of Distraction Osteogenesis in Limb Salvage for Tumors.

Modern technology and advances in medicine have facilitated increasing rates of limb salvage in the treatment of sarcomas. Orthopedic oncologists have a wide array of reconstruction options for limb salvage, ranging from allografts to endoprosthesis reconstruction. Limb lengthening is another option available to an orthopedic oncologist faced with bony defects and limb length discrepancies following resection. This review provides a brief history of limb lengthening, the principles of distraction osteogenesis, and current applications in orthopedic oncology. Considering the complications and challenges associated with the lengthening process, appropriate patient selection and thorough patient counseling is key to optimizing outcomes.

Skeletal expansion via craniofacial distraction osteogenesis technique in syndromic craniosynostosis: impact on ophthalmic parameters.

BACKGROUND: This study aims to compare the changes in ophthalmic parameters among syndromic craniosynostosis patients who underwent craniofacial skeletal expansion procedures via distraction osteogenesis (DO). METHOD: A retrospective study was conducted involving syndromic craniosynostosis patients who underwent surgical expansion via the DO technique from the year 2012 to March 2022. Changes in six parameters which consist of visual acuity, refractive error, optic disc health, intraocular pressure, degree of proptosis and orbital volume were measured objectively pre and post-surgery. For categorical parameters, the Chi-square cross-tab test was done. Paired sample T-test was used for normally distributed variables. Wilcoxon signed-rank test was used for non-normally distributed data. RESULTS: Visual impairment was present in 21.4% of eyes before surgery and increased to 28.5% post-surgery. Three patients had changes of refractive error post-surgery with one developed hypermetropia, another developed anisometropia and the last had improvement to no refractive error. Two patients had optic disc swelling which was resolved post-surgery. Intraocular pressure changes were inconsistent post-surgery. All patients achieved a significant reduction in the degree of proptosis post-surgery. Orbital volume calculation using computed tomography (CT) scans shows a significant increase in volume post-surgery for all patients. CONCLUSION: Our study shows a significant increase in orbital volume post-surgery with a reduction in the degree of proptosis. Optic disc and nerve health improved after the surgery. Changes in terms of visual acuity, refractive error and IOP were inconsistent after the surgical intervention.

Soft-tissue, non-osteogenic distraction of the mandible and lower face in bilateral hemifacial microsomia-technical report.

The aim of this study is to present a sequential strategy of soft-tissue, non-osteogenic distraction with a novel device, followed by microvascular bony reconstruction for severe cases of mandibular hypoplasia. The case of a 21-year-old woman with Goldenhar syndrome is presented, whose mandible remained severely hypoplastic despite previous attempts at distraction and was not suitable for further osteogenic distraction. Soft tissue deficiency and pin track scarring prevented free fibular transfers. A personalized distractor, anchored to the cranium and the mandibular symphysis, was designed to expand the soft tissues while allowing for physiological temporomandibular joint (TMJ) movement without compression forces. Internal distractors were placed along the osteotomies to prevent condylar luxation. After completion of the soft tissue distraction, the native mandible was resected except for the condyles and reconstructed with two free fibula flaps. This report represents the proof of concept of a sequential approach to severe lower face soft-tissue and bone deficiency, which preserves TMJ function and avoids the transfer of poorly matched skin to the face.

Changes in mandibular position during midface distraction in patients with syndromic craniosynostosis.

The purpose of this study was to evaluate changes in mandibular position during midface distraction. Midface distraction was performed in patients with syndromic craniosynostosis to increase upper airway volume. Although this treatment resulted in changes in occlusion, the concomitant changes in mandibular position were poorly understood. In this retrospective study, three-dimensional (3D) cephalograms were obtained before and after midface distraction in 15 patients with syndromic craniosynostosis. Perioperative polysomnography scores and changes in maxillary and mandibular position, mandibular volume, and upper airway volume were analyzed. Results showed a significant improvement in apnea-hypopnea index (AHI) (from 20.6 ± 21.3 to 6.9 ± 5.1, p < 0.05) and upper airway volume (from 2951.65 ± 2286.38 to 5218.04 ± 3150.05 mm3, p < 0.001). When the lowest point of the sella turcica was set as the reference point, the mandible moved significantly in an anterior direction (from 47.9 ± 11.5 to 51.9 ± 9.8 mm, p < 0.05). Mandibular volume did not change significantly perioperatively (from 32530.19 ± 10726.01 to 35590.50 ± 14879.21 mm3, p = 0.10). There were positive correlations between the rates of improvement in AHI and the amount of mandibular movement in the anterior and inferior directions (both p < 0.05). Within the limitations of the study, it seems that the mandible moved in the anterior-inferior direction after midface distraction, and the amount of movement correlated with improvement in respiratory function. Therefore, it is important to consider the position of the mandible when determining the direction of midface distraction, as it may influence the therapeutic effect.

Does distraction osteogenesis improve the airway volume and quality of life of obstructive sleep apnoea patients secondary to temporomandibular joint ankylosis?

Temporomandibular joint (TMJ) ankylosis leads to mandibular micrognathia that severely collapses the upper airway causing obstructive sleep apnoea (OSA), resulting in deterioration and compromise in the quality of life (QoL) of patients. In this study, we aimed to calculate airway volume changes, apnoea-hypopnoea index (AHI), and improvement in quality of life before and after distraction osteogenesis (DO). Fourteen Patients with OSA secondary to TMJ ankylosis at a mean (SD) age of 17.5 (5.43) years were enrolled in this prospective study. Multivector mandibular distractors were used in all patients following the standard Ilizarov distraction protocol with a mean (SD) anteroposterior distraction of 16.21 (4.37) mm and a consolidation period of 116.92 (14.35) days. The patients were followed up for six months. A polysomnography test (PSG) was done to quantify AHI and a low-dose computed tomographic scan was done to calculate airway volume using Dolphin medical imaging software pre and post-DO. The QoL of the patients was calculated using the OSA-18 questionnaire. Results analysis depicted that the mean (SD) preoperative AHI was 51.44 (37.99)/h which was improved to 9.57 (9.74)/h (p = 0.001) after DO. Airway volume was calculated on Dolphin software before and after DO showed a significant improvement in airway volume by 121.12% (98.30)%. Similarly, the OSA-18 questionnaire showed significant improvement in QoL from severe to normal. This study suggested that DO increases the corpus length of the mandible, leading to an increment in airway volume, which improves the QoL.

Skeletal stability of inter-molar mandibular distraction osteogenesis in growing patients.

INTRODUCTION: The aim of this retrospective study was to firstly assess the stability of surgical advancement using inter-molar mandibular distraction osteogenesis (IMDO) and secondly to assess the impact of the surgical intervention on subsequent mandibular growth in patients with residual growth. METHODS: The sample consisted of 17 (13F and 4M) consecutively treated patients who underwent IMDO and orthodontic treatment. Cephalometric analysis was performed at three time points: T0 prior to distraction; T1 post-distraction immediately prior to surgical removal of the distractors; and T2 following completion of orthodontic treatment when the final lateral cephalogram was taken (0.86-4.37 years after T1). Statistical comparison of lower facial height, mandibular length, growth, condylar position and anterior mandibular rotation was performed. RESULTS: No association was found between changes in any of the cephalometric measurements and the length of the follow-up interval. The anterior mandibular segment underwent clockwise rotation during distraction and recovered to near its pre-distraction angulation during remodelling. An increase in the lower facial height of 1.88 ± 2.81mm also occurred during distraction (T0-T1) and was maintained during the follow-up period (T1-T2). Post-distraction (T1-T2) growth of lower facial height (p value 0.872) and mandibular length (p value 0.251) showed no association when compared to an untreated control group and an overall reduction in growth was reported. CONCLUSIONS: IMDO was highly stable within a follow-up period of 2.3 ± 0.9 years; however, growth appears to have been inhibited.

Objective and subjective evaluation of the efficacy of trans-sutural distraction osteogenesis: A correlation analysis between computed tomography measurements and FACE-Q scores.

Previous studies on the efficacy of trans-sutural distraction osteogenesis (TSDO) to treat midface hypoplasia caused by cleft lip and palate (CLP) have mainly focused on objective measurements while ignoring the subjective feelings of patients. This study aimed to analyse the changes in and correlation between computed tomography (CT) measurements and FACE-Q scores in patients who underwent TSDO by performing a comprehensive evaluation from both objective and subjective perspectives. This retrospective study included 25 patients with an average age of 10.7 years who had midface hypoplasia caused by CLP and underwent TSDO between August 2018 and December 2022. The average follow-up time was 18.8 ± 7.7 months. Facial morphology and CT measurements, including A-CR, N-A⊥HR, the SNA angle and the L-ZA, indicated significant improvements in midface concavity (all p < 0.0001). All FACE-Q scores (except for facial function) exhibited a significant increase. The ΔA-CR, ΔN-A⊥HR, and ΔSNA angle were strongly correlated with specific aspects of the FACE-Q-Appearance items, including the ΔFACE-Q-Appearance of the cheeks (all p < 0.0001), the ΔFACE-Q-Appearance of the face (all p < 0.0001), the ΔFACE-Q-Appearance of the jaws (all p < 0.01), the ΔSatisfaction with decision (all p < 0.0001) and the ΔSatisfaction with outcome (all p < 0.001). However, the ΔA-CR, ΔN-A⊥HR, and ΔSNA were weakly correlated with other FACE-Q-Health-related quality of life and function items. These findings suggest that both CT findings and FACE-Q scores have their own emphases and advantages. It is necessary to establish an integrated curative effect evaluation model that combines FACE-Q scores with CT measurements to evaluate both the physical health and psychological status of patients.

Enhanced Bone Regeneration through Regulation of Mechanoresponsive FAK-ERK1/2 Signaling by ZINC40099027 during Distraction Osteogenesis.

Background: Focal adhesion kinase (FAK) is activated by mechanical stimulation and plays a vital role in distraction osteogenesis (DO), a well-established but lengthy procedure for repairing large bone defects. Both angiogenesis and osteogenesis contribute to bone regeneration during DO. However, the effects of ZINC40099027 (ZN27), a potent FAK activator, on angiogenesis, osteogenesis, and bone regeneration in DO remain unknown. Methods: The angiogenic potential of human umbilical vein endothelial cells (HUVECs) was evaluated using transwell migration and tube formation assays. The osteogenic activity of bone marrow mesenchymal stem cells (BMSCs) was assessed using alkaline phosphatase (ALP) and alizarin red s (ARS) staining. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence staining were used to assay angiogenic markers, osteogenic markers, and FAK-extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. In vivo, a rat tibia DO model was established to verify the effects of ZN27 on neovascularization and bone regeneration using radiological and histological analyses. Results: ZN27 promoted the migration and angiogenesis of HUVECs. Additionally, ZN27 facilitated the osteogenic differentiation of BMSCs, as revealed by increased ALP activity, calcium deposition, and expression of osteogenesis-specific markers. The ERK1/2-specific inhibitor PD98059 significantly hindered the effects of ZN27, suggesting the participation of FAK-ERK1/2 signaling in ZN27-enhanced angiogenesis and osteogenesis. As indicated by improved radiological and histological features, ZN27 induced active angiogenesis within the distraction area and accelerated bone regeneration in a rat DO model. Conclusion: Our results show that ZN27 targets FAK-ERK1/2 signaling to stimulate both angiogenesis and osteogenesis, and ZN27 accelerates bone regeneration in DO, suggesting the therapeutic potential of ZN27 for repairing large bone defects in the mechanobiological environment during DO.

Evaluation of simultaneous bilateral femoral distraction osteogenesis with antegrade intramedullary lengthening nails in achondroplasia with rhizomelic short stature: a retrospective study of 15 patients with a minimum follow-up of 2 years.

BACKGROUND AND PURPOSE: Bilateral femoral distraction osteogenesis in patients with achondroplasia is insufficiently reported. We aimed to perform the first study that exclusively analyzed simultaneous bilateral femoral distraction osteogenesis with motorized intramedullary lengthening nails via an antegrade approach in patients with achondroplasia focused on reliability, accuracy, precision, and the evolving complications. PATIENTS AND METHODS: In this retrospective singlecenter study we analyzed patients with achondroplasia who underwent simultaneous bilateral femoral lengthening with antegrade intramedullary lengthening nails between October 2014 and April 2019. 15 patients (30 femoral segments) of median age 14 years (interquartile range [IQR] 12-15) were available for analysis. The median follow-up was 29 months (IQR 27-37) after nail implantation. RESULTS: The median distraction length per segment was 49 mm (IQR 47-51) with a median distraction index of 1.0 mm/day (IQR 0.9-1.0), and a median consolidation index of 20 days/cm (IQR 17-23). Reliability of the lengthening nails was 97% and their calculated accuracy and precision were 96% and 95%, respectively. The most common complication was temporary restriction of knee range of motion during distraction in 10 of 30 of the lengthened segments. 1 patient was treated with 2 unplanned additional surgeries due to premature consolidation. CONCLUSION: The method is reliable and accurate with few complications.

Critical size bone defects managed with modern techniques of bone transport: An update.

Bone transport is one of several techniques that has been proven to be effective in addressing critical bone loss. While it was first described over 100 years ago, modifications to this technique coupled with advances in technology have allowed us to perform bone transport with higher success rates and reduced complication rates. Modern techniques of bone transport aim to shorten the duration of time an external fixator is utilized to reduce its associated complications and burden to patients. We present an update on modern techniques of bone transport for critical size defects and methods to shorten the external fixation time.

3D-CT measurements of facial symmetry in severe CFM patients: A comparative study between mandibular ascending ramus distraction osteogenesis and bone grafting.

This study aims to compare the effects of mandibular distraction osteogenesis (MDO) and bone grafting on the facial symmetry of children with Pruzansky-Kaban type IIB and III craniofacial microsomia (CFM). Medical records and three-dimensional computed tomography (3D-CT) data of CFM patients who had primarily undergone MDO and bone grafting were collected. A retrospective analysis of pre-and post-operative 3D imaging data was conducted to compare the improvement rate in facial symmetry between the two groups based on occlusal cant, affected/unaffected ramus height ratio and chin point deviation. The data were tested for normality using the Shapiro-Wilk test. When the data followed a normal distribution, a paired sample t-test was employed for the comparison between preoperative and postoperative data. When the data did not follow a normal distribution, the Wilcoxon signed-rank test for paired samples was used for preoperative and postoperative comparison. The study included 18 children with type IIB and III CFM, 11 in the MDO group and 7 in the bone grafting group. In the MDO group, postoperative Gn-FH and Gn-Cor distances increased significantly, whereas the postoperative Gn-Mid distance decreased significantly. Occlusal cant decreased significantly and ramus height affected/unaffected ratio increased significantly after MDO. In the bone graft group, there was no statistically significant difference in the postoperative ratios of chin deviation, occlusal cant, and ramus height affected/unaffected compared to the preoperative values. Compared to bone grafting, MDO can significantly enhance ramus height ratio, level occlusal plane, and centralize the chin point among patients with CFM. Furthermore, MDO achieves superior enhancements in facial symmetry.

Hemi one-piece distraction osteogenesis for unilateral coronal craniosynostosis.

INTRODUCTION: It 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. METHODS: Two 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. RESULTS: The 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). CONCLUSION: This 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.

Efficacy of navigation system-assisted distraction osteogenesis for hemifacial microsomia based on artificial intelligence for 3 to 18 years old: study protocol for a randomized controlled single-blind trial.

BACKGROUND: Mandibular distraction osteogenesis (MDO) is a major part of the treatment for hemifacial microsomia patients. Due to the narrow surgical field of the intraoral approach, osteotomy accuracy is highly dependent on the surgeons' experience. Electromagnetic (EM) tracking systems can achieve satisfying accuracy to provide helpful real-time surgical navigation. Our research team developed an EM navigation system based on artificial intelligence, which has been justified in improving the accuracy of osteotomy in the MDO in animal experiments. This study aims to clarify the effect of the EM navigation system in improving the MDO accuracy for hemifacial microsomia patients. METHODS: This study is designed as a single-centered and randomized controlled trial. Altogether, 22 hemifacial microsomia patients are randomly assigned to the experiment and control groups. All patients receive three-dimensional CT scans and preoperative surgical plans. The EM navigation system will be set up for those in the experiment group, and the control group will undergo traditional surgery. The primary outcome is the surgical precision by comparing the osteotomy position of pre- and postoperative CT scan images through the Geomagic Control software. The secondary outcomes include mandibular symmetry (occlusal plane deviation angle, mandibular ramus height, and body length), pain scale, and complications. Other indications, such as the adverse events of the system and the satisfactory score from patients and their families, will be recorded. DISCUSSION: This small sample randomized controlled trial intends to explore the application of an EM navigation system in MDO for patients, which has been adopted in other surgeries such as orthognathic procedures. Because of the delicate structures of children and the narrow surgical view, accurate osteotomy and protection of nearby tissue from injury are essential for successful treatment. The EM navigation system based on artificial intelligence adopted in this trial is hypothesized to provide precise real-time navigation for surgeons and optimally improve patient outcomes, including function and aesthetic results. The results of this trial will extend the application of new navigation technology in pediatric plastic surgery. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2200061565. Registered on 29 June 2022.

The Montreal Children's Hospital Experience Managing Robin Sequence: An Analysis of Outcomes and Algorithm for Surgical Technique Selection.

BACKGROUND: The development of mandibular distraction osteogenesis (MDO) and tongue-lip adhesion (TLA) has led to significant improvements in respiratory outcomes for the Robin sequence (RS) population. Despite such advances, there continues to be debate regarding management strategies. The authors present their experience managing the RS population with insights on technique selection. METHODS: A retrospective review of RS patients treated at the senior author's institution from 2003 to 2021 was conducted. Baseline patient demographics and clinical parameters including feeding and respiratory status were recorded. Outcomes included the need for tracheostomy or tracheostomy, decannulation rates, and feeding status. Patients were evaluated through overnight oximetry and drug-induced sleep endoscopy (DISE). Outcomes were stratified according to management technique (MDO, TLA, versus conservative) and compared through statistical analysis. RESULTS: Fifty-nine RS patients were included. Twenty-eight were managed conservatively, 19 underwent MDO, 10 underwent TLA, one underwent both TLA and MDO, and one underwent tracheostomy primarily. Overall, 1.7% of the cohort required a tracheostomy and 86% achieved oral feeding after the procedure. The MDO cohort had lower Apgar scores and mean birth weight compared with the conservative and TLA cohorts ( P < 0.05). There were no statistical differences in respiratory and feeding outcomes across all three cohorts. CONCLUSIONS: A therapeutic algorithm was developed with insight into the use of DISE and risk stratification with overnight oximetry to guide procedural selection. Using this approach, safe and satisfactory respiratory outcomes were achieved with a low tracheostomy rate. Risk stratification is possible without polysomnography, and DISE is a promising tool (that requires further validation) for procedural selection in this population. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.