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.

Posterior cranial vault distraction in children with syndromic craniosynostosis: the era of biodegradable materials-a comprehensive review of the literature and proposed novel global application

Distraction osteogenesis is utilized to increase intracranial volume in the treatment of restrictive pathologies, most commonly syndromic synostosis. Children too young for open calvarial vault expansion or other systemic or local contraindications to a direct reconstructive approach benefit greatly from distraction osteogenesis, typically addressing posterior vault expansion. Wound infection, cerebrospinal fluid (CSF) leak, device failure, need for a second surgery for removal, and cost, are issues that can limit the use of this approach. These challenges are more pronounced in low- and middle-income countries (LMICs) due to lack of access to the device, the financial burden of the need for a second surgery, and the severity of the implications of infection and CSF leak. Over the last five decades, there has been an increased acceptance of bioresorbable instrumentation in craniofacial surgery. Poly L-lactic acid, polyglycolic acid, and polydioxanone are the most commonly used polymers. New resorbable fixation tools such as ultrasound-activated pins and heat-activated pins are superior to conventional bioresorbable screws in allowing attachment to thinner bone plates. In this paper, we present a review of the literature on cranial vault distraction and the use of bioresorbable materials and propose a novel design of a fully absorbable cranial distractor system using external magnetic distraction control, eliminating the need for external activation ports and a second surgery to remove the hardware. The application of this technology in LMIC settings could advance access to care and treatment options for patients with syndromic synostosis.

Orthopedic mechanism analysis of growing rod distraction for early-onset scoliosis based on 3D morphological parameters

Traditional growing rod (TGR) provides a corrective moment for deformed segments to straighten the spine, whose clinical efficacy has proven positive and growth-friendly. However, an insufficient understanding of orthopedic mechanisms can affect the development of clinical strategies. This research attempts to analyze the spine that has undergone four distraction operations: exploring the spinal orthopedic mechanism, including alignment, growth, and morphology. In this study, the spinal morphology curves were illustrated in three human planes to exhibit the changes in spinal alignment. The spinal growth characteristics were measured to discuss the unsynchronized and diminishing growth rate. The spinal deformations were evaluated to indicate asymmetric growth. As a result, the spinal alignment changes indicated the orthopedic process improved, but the re-unbalance occurred after multiple distractions. Then, unsynchronized growth existed in the superior and inferior segments, and the growth rate over every distraction diminished. Finally, asymmetric growth was indicated as the axial/circumferential growth ratio getting greater and the cuneate level approaching normal. Accordingly, a TGR is growth-friendly, but combining the osteotomy fusion of lumbar segments for severe early-onset scoliosis may be an excellent choice to solve the insufficient corrective stimulation. Regarding the distraction process, reshaping before the final fusion can fix the balance loss, and a prolonged distraction frequency fits the law of diminishing return. In conclusion, studying orthopedic mechanisms based on morphological measurement can guide clinical strategy optimization.

Does Distraction Lower Risk of VPI Compared to Conventional Maxillary Advancement? A Retrospective Cohort Study of Adolescents with Cleft Palate

OBJECTIVE

To determine whether method of maxillary advancement in adolescents with cleft palate with or without cleft lip (CP ± L) influences post-operative velopharyngeal function.

DESIGN

Retrospective cohort.

SETTING

Pediatric Tertiary Care Hospital.

PARTICIPANTS

One hundred and ninety-nine patients with CP ± L after LeFort I osteotomy for maxillary advancement at our institution between January 2007 and June 2019.

INTERVENTIONS

LeFort I osteotomy via distraction osteogenesis (DO) or conventional osteotomy (CO).

MAIN OUTCOME MEASURES

Patients who underwent DO or CO were compared for the presence of new velopharyngeal insufficiency (VPI), as measured by perceptual rating by a craniofacial speech-language pathologist.

Of the 199 patients who underwent maxillary advancement, 126 were available for analysis. The DO group was younger, male, and had more severe maxillary hypoplasia. Following surgery, 17/41 (41.5%) of the DO group had new VPI, compared to just 23/85 (27.1%) of the CO group. After adjusting for cleft type and predicted maxillary advancement, however, there was not sufficient evidence to reject the null hypothesis of no difference in risk of post-operative VPI between the two surgical groups (prevalence ratio [PR] 1.40, 95% CI 0.68-2.90). Increased prevalence of VPI after DO versus CO was primarily observed among patients with a pre-operative velopharyngeal need ratio < 0.8 (PR = 2.01, 95% CI 0.79-5.10) and patients with normal velopharyngeal function pre-operatively (PR = 2.86, 95% CI 0.96-8.50).

Our results suggest an increased rather than decreased risk of VPI following DO relative to CO. This association is primarily seen among those with a smaller velopharyngeal ratio or perceptually normal velopharyngeal function pre-operatively.

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.

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.

LATS1/YAP1 Axis Controls Bone Regeneration on Distraction Osteogenesis by Activating Wnt/β-Catenin

The Hippo signaling pathway inhibits cell growth, and its components and functions are highly conserved in mammals. LATS1 is a core component of the Hippo signaling pathway associated with lymphatic invasion, astrogliosis, apoptosis, and autophagy. Nevertheless, the role of Hippo/LATS1 in osteogenesis remains unclear. In this study, we used ribonucleic acid (RNA) lentiviruses to inhibit the expression of Lats1 in bone marrow-derived stem cells (BMSCs) and distraction osteogenic regions in rats. Increased osteogenic, proliferative, and migratory abilities of BMSCs were observed in Lats1-inhibited BMSCs, while these phenotypes were partially reversed by YAP1 inhibition. In vivo, we found that the LATS1/YAP1 axis promoted osteogenesis during distraction osteogenesis (DO). β-catenin was positively correlated with YAP1 expression in vivo and in vitro. When YAP1 was strongly positive in the nucleus, β-catenin expression was upregulated; when YAP1 expression was inhibited by verteporfin, β-catenin was not expressed in the nucleus. These findings suggest that the LATS1/YAP1 signaling axis promotes DO by activating the Wnt/β-catenin signaling pathway. This study provides insights into the molecular mechanism of osteogenesis and a potential therapeutic strategy for bone regeneration in DO by associating with LATS1/YAP1-β-catenin.

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.

Mid-term effect of mandibular distraction osteogenesis on clinical and polysomnography findings of patients with Robin sequence

The study aimed to evaluate the mid-term effect of MDO in children with Robin sequence (RS). In this case series, 13 patients with RS who underwent MDO were followed up for more than 5 years. Data were collected using clinical history and physical examination. Polysomnography was performed and endoscopic evaluations of the airway was performed if patients still presented obstructive signs of upper airways and/or dysphagia. The patients' clinical signs improved in the mid-term after versus before MDO (inspiratory noise, 92,3% vs 30,8%; apnea, 84,6% vs 7,7%; cyanosis, 76,9% vs 0%; desaturations, 69,2% vs 0%; and suprasternal/intercostal retractions, 61,5% vs 0%; p < 0.05). Statistically significant improvement was noted in the following polysomnographic parameters evaluated in the pre and postoperative mid-term: apnea-hypopnea index, total sleep time and desaturation index (p < 0.05). Within the limitations of the study it seems that MDO is an effective surgical option for children with RS, not only in the short term as previously demonstrated, but also in the mid-term.

Reconstruction of Bony Defects With Motorized Intramedullary Nails After Tumor Resection

Motorized intramedullary lengthening nails allow for transport of a bone segment for limb lengthening, deformity correction, healing of nonunion, and intercalary distraction osteogenesis. Resection of tumors involving the bone can result in substantial defects that require reconstruction. Use of these nails allows for a biologic reconstruction with the incorporation of allograft or by distraction osteogenesis. Limb lengthening after an internal hemipelvectomy where the hip joint is resected can be performed to improve gait, decrease pain, and prevent the need for a custom shoe or shoe lift. Using these nails in compression aids the incorporation of intercalary allografts and prevents stress shielding and stress risers within the graft when compared with plating. It also allows for a subsequent lengthening of the limb using the same implant. Plate-assisted bone segment transport or the use of a bone transport nail allows for a true biologic reconstruction of an intercalary defect using distraction osteogenesis. These implants provide the orthopaedic oncologist with more options for reconstruction and the potential to improve the function and outcomes of their patients.

Developments in circular external fixators: A review

Circular external fixators (CEFs) are successfully used in orthopedics owing to their highly favorable stiffness characteristics which promote distraction osteogenesis. Although there are different designs of external fixators, how these features produce optimal biomechanics through structural and component designs is not well known. Therefore, the aim of this study was to conduct a review on CEFs following the PRISMA statement. A search for relevant research articles was performed on Scopus and PubMed databases providing the related keywords. Furthermore, a patent search was conducted on the Google Patent database. 126 records were found to be eligible for the review. Different designs of CEFs were summarized and tabulated based on their specific features. A bibliometric analysis was also performed on the eligible research papers. Based on the findings, the developments of CEFs in terms of materials, automation, adjustment methods, component designs, wire-clamping, and performance evaluation have been extensively discussed. The trends of the CEF design and future directions are also discussed in this review. Significant research gaps include a lack of consideration towards ease of assembly, effective wire-clamping methods, and CEFs embedded with online patient-monitoring systems, among others. An apparent lack of research interest from low-middle and low-income countries was also identified.

Advances in the Application of Bone Transport Techniques in the Treatment of Bone Nonunion and Bone Defects

Bone nonunion and bone defects frequently occur following high-energy open injuries or debridement surgeries, presenting complex challenges to treatment and significantly affecting patients' quality of life. At present, there are three primary treatment options available for addressing bone nonunion and bone defects: vascularized bone grafts, the Masquelet technique, and the Ilizarov technique. The Ilizarov technique, also known as distraction osteogenesis, is widely favored by orthopedic surgeons because of several advantages, including minimal soft tissue requirements, low infection risk, and short consolidation time. However, in recent years, the application of the Masquelet technique has resulted in novel treatment methods for managing post-traumatic bone infections when bone defects are present. Although these new techniques do not constitute a panacea, they continue to be the most commonly employed options for treating complex large bone nonunion and bone defects. This review evaluates the currently available research on the Ilizarov and Masquelet bone transport techniques applied at various anatomical sites. Additionally, it explores treatment durations and associated complications to establish a theoretical foundation that can guide clinical treatment decisions and surgical procedures for the management of bone nonunion and bone defects.

Factors affecting the relapse of maxilla and soft tissues of nose, upper lip and velopharyngeal structures after maxillary advancement in cleft patients

The objectives of this study were to find the factors affecting the relapses after maxillary advancement in cleft patients. This retrospective study included 25 cleft patients. The serial lateral cephalograms were used for the evaluation of the maxilla and the soft tissue relapses in 1-year post-operative period. The skeletal relapse rate correlated with the amount of skeletal movement only in horizontal direction (r = 0.483, p = 0.015). The patients with significant skeletal relapse did not have different amount of soft tissue relapses when compared to the patients without significant skeletal relapse, except for the A' point. Relapses of the soft tissue parameters of the upper lip and nose were correlated with the upper incisor tip position horizontally and vertically. When comparing the patients who underwent maxillary distraction (DO) with the patients who underwent conventional orthognathic surgery (CO), the DO group had greater NLA relapse and increase of pharyngeal depth than the CO group.

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.

Prevalence and Management of Laryngomalacia in Patients With Pierre Robin Sequence

OBJECTIVE

To characterize the prevalence and presentation of laryngomalacia and efficacy of supraglottoplasty (SGP) in a cohort of patients with Pierre Robin Sequence (PRS).

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care children's hospital.

PATIENTS, PARTICIPANTS

Consecutive patients with PRS born between January 2010 and June 2018.

MAIN OUTCOME MEASURES

Chart review included demographics, comorbid airway obstruction including laryngomalacia, timing of surgical interventions, clinical symptoms, sleep study data, and modified barium swallow study data.

126 patients with PRS were included; 54% had an associated syndrome, 64% had an overt cleft palate, and 22% had a submucous cleft palate. 64/126 were noted to have laryngomalacia (51%). Patients with concurrent PRS and laryngomalacia were significantly more likely to have submucous cleft palate (P = .005) and present with aspiration with cough (P = .01) compared to patients with PRS without laryngomalacia. Patients with concurrent laryngomalacia and PRS showed a significant decrease in apnea-hypopnea index (AHI) and obstructive AHI (OAHI) after mandibular distraction, with a median AHI and OAHI improvement of 22.3 (P = .001) and 19.8 (P = .002), respectively. Patients who underwent only SGP did not show significant improvement in these parameters (P = .112 for AHI, P = .064 for OAHI).

The prevalence of laryngomalacia in our PRS cohort was 51%. Patients with PRS and laryngomalacia are more likely to present with overt aspiration compared to patients with PRS without laryngomalacia. These data support that laryngomalacia does not appear to be a contraindication to pursuing MDO.

Oxycephaly-systematic review, case presentation, and diagnostic clarification

PURPOSE

Oxycephaly is a specific phenotype of multi-suture craniosynostosis that is often misrepresented. This study aims to review the relevant literature, clarify the diagnostic criteria, and present an alternate approach to its management.

METHODS

Published literature regarding oxycephaly was reviewed from 1997, when the largest series was published, until 2022. All cases at a single institution were then retrospectively reviewed.

RESULTS

Over the last 25 years, four studies met the inclusion criteria, none of which specifically defined oxycephaly. One case, in one study, was potentially consistent with the phenotype. An institutional review yielded two patients who met the original diagnostic criteria set forth by Renier and Marchac. Both patients had unexplained speech delays, mild retinal nerve fiber layer thickening, and diffuse inner table scalloping, along with the characteristic oxycephalic phenotype. One patient also had a direct intracranial pressure (ICP) measurement of 25 mmHg, and the other had a Chiari I malformation. Both were treated with posterior vault distraction osteogenesis (PVDO) to alleviate the cephalo-cranial disproportion while simultaneously allowing for turricephaly correction.

CONCLUSIONS

Oxycephaly presents with late onset multi-suture fusion. Patients have patent sutures at birth. Midface hypoplasia and known syndromic associations are absent. Patients demonstrate supraorbital recession, an obtuse fronto-nasal angle, and turricephaly without substantial brachycephaly. Over 60% of patients have symptomatic ICP elevation, the presentation of which ranges from headaches to rapidly progressive blindness. This rare form of craniosynostosis is particularly virulent and likely often missed due to diagnostic ambiguity and its relatively mild phenotype.

Long-term follow-up of a patient diagnosed with Crouzon syndrome who underwent Le Fort I and III distraction osteogenesis using a rigid external distractor system

OBJECTIVE

This case report describes the successful treatment of a patient with Crouzon syndrome with severe midfacial deficiency and malocclusion, including reverse overjet.

MATERIALS AND METHODS

In Phase I treatment, maxillary lateral expansion and protraction were performed. In Phase II treatment, after lateral expansion of the maxilla and leveling of the maxillary and mandibular dentition, an orthognathic approach including simultaneous Le Fort I and III osteotomies with distraction osteogenesis (DO) was used to improve the midfacial deficiency.

RESULTS

After DO, 12.0 mm of the medial maxillary buttress and 9.0 mm of maxillary (point A) advancement were achieved, which resulted in a favorable facial profile and stable occlusion.

CONCLUSION

Even after 8 years of retention, the patient's profile and occlusion were preserved without any significant relapse.

Is physeal distraction osteogenesis a good choice to treat CPT patients with tibial shortening?

The purpose of this study was to evaluate the healing index and complications of distraction osteogenesis through the physis in children with Congenital pseudarthrosis of the tibia (CPT) using Ilizarov external fixation device. Nine children with CPT who underwent distraction osteogenesis through the physis surgery with an Ilizarov external fixation device between June 2018 and August 2020 were included in the study. The average follow-up time was 36.1 months. X-ray examination was performed 1 month after physis lengthening, and the callus quality was evaluated using the Li classification. Any complications and the quality of the callus after tibial lengthening were followed up. The average age at the time of operation was 9.4 years, and the average follow-up time was 36.1  months. The average lengthening length of children with CPT was 6.6 cm. The incidence of good callus morphology was 100%, and the healing index was 51.1 d/cm. The average fixation time of the external fixation device was 316 days. Needle tract infection occurred in one case, ankle stiffness occurred in one case, ankle plantar flexion 20° deformity occurred in one case, angular deformity of the tibial lengthening segment occurred in one case (7°) and limited movement of knee joint occurred in one case (0-20°-70°). The osteogenic quality of the patients of distraction osteogenesis through the physis with tibial shortening and small diameter of the proximal tibia is good, which provides a choice of operation for the children with CPT.

Biomechanical Performance of Biodegradable Screw Fixation in Mandibular Distraction Osteogenesis

Internal distraction devices are commonly used in congenital micrognathia. The eventual need for device and screw removal can be challenging, requiring extensive dissection and disturbance of bone regenerate. Bioabsorbable poly-L-lactide (PLLA) screws, compared to traditional titanium screws, simplify device removal. Previous in vivo studies have found that the maximal compressive force generated by mandibular distraction is 69.4N. We hypothesized that PLLA screws could support these compressive/distraction forces. Ten mandibles were obtained from 5 canine cadavers. Paired mandibles from the same cadaver were each fixated to a mandibular distractor with eight screws (either titanium or PLLA). Devices were each set to 15 and 30   mm of distraction distance. Compression force of 80   N was then generated parallel to the axis of the distraction device. Distractor displacement was measured to detect any mechanical failure during this pre-set load. Finally, if no failure was observed at 80   N, a load-to-failure compression test was done in the PLLA group to determine the mechanical failure point. All distractors in both the titanium and PLLA screw groups withstood 80   N of compression without failure. When the load-to-failure test was performed in the PLLA group, the average device failure point was 172.8   N (range 148-196   N). Review of high-frame-rate video demonstrated that all failures occurred due to the PLLA screws breaking or falling out. Bioabsorbable PLLA screws can withstand compressive forces more than double that of the maximal in vivo forces needed during mandibular distraction. These screws may be an acceptable alternative for the fixation of internal mandibular distractors.

The effect of intermittent parathyroid hormone on bone lengthening: current evidence to inform future effective interventions

PURPOSE

Recent studies have demonstrated the positive effects of parathyroid hormone (PTH) on bone healing, and findings support the use of PTH to accelerate bone healing following distraction osteogenesis. The goal of this review was to compile and discuss the mechanisms potentially underlying the effects of PTH on newly formed bone following a bone-lengthening procedure incorporating all relevant evidence in both animal and clinical studies.

METHODS

This review summarized all evidence from in vivo to clinical studies regarding the effects of PTH administration on a bone-lengthening model. In addition, a comprehensive evaluation of what is currently known regarding the potential mechanisms underlying the potential benefits of PTH in bone lengthening was presented. Some controversial findings regarding the optimal dosage and timing of administration of PTH in this model were also discussed.

RESULTS

The findings demonstrated that the potential mechanisms associated with the action of PTH on the acceleration of bone regeneration after distraction osteogenesis are involvement in mesenchymal cell proliferation and differentiation, endochondral bone formation, membranous bone formation, and callus remodeling.

CONCLUSIONS

In the last 20 years, a number of animal and clinical studies have indicated that there is a prospective role for PTH treatment in human bone lengthening as an anabolic agent that accelerates the mineralization and strength of the regenerated bone. Therefore, PTH treatment can be viewed as a potential treatment to increase the amount of new calcified bone and the mechanical strength of the bone in order to shorten the consolidation stage after bone lengthening.

[External fixation for the correction of complex deformities : From the classic Ilizarov ring fixator to modern software-driven hexapod fixators]

The history and development of circular fixation is closely aligned with the history of limb lengthening. Gavriil A. Ilizarov not only developed his circular fixator, but he also was the first to research and publish on distraction osteogenesis. Progress and dissemination of the method was initially based on individual pioneers; a standardized nomenclature and annual courses led to a wider dissemination. The introduction of the Taylor spatial frame in 1997 was a game changer. Although various groups had already developed Hexapod-fixators, it was the TSF that hit the market and achieved market presence. After the patent for TSF expired, many companies developed hexapod fixators with various modifications. A new version of the TSF, the Smart TSF, which included an intuitive planning software, was introduced in Baltimore in 2021. The introduction of intramedullary lengthening nails at the beginning of the 2000s and the wide dissemination starting approximately 2013 rendered external fixation obsolete for certain indications. However, ring fixators are still the method of choice for complex reconstruction of deformity in traumatology, as well as in pediatric orthopedics in the presence of open growth plates.

[The airway management and treatment of newborns with micrognathia and laryngomalacia]

Objective:To explore the perioperative airway management and treatment of newborns with micrognathia and laryngomalacia. Methods:From January to December 2022, a total of 6 newborns with micrognathia and laryngomalacia were included. Preoperative laryngoscopy revealed concomitant laryngomalacia. These micrognathia were diagnosed as Pierre Robin sequences. All patients had grade Ⅱ or higher symptoms of laryngeal obstruction and required oxygen therapy or non-invasive ventilatory support. All patients underwent simultaneous laryngomalacia surgery and mandibular distraction osteogenesis. The shortened aryepiglottic folds were ablated using a low-temperature plasma radiofrequency during the operation. Tracheal intubation was maintained for 3-5 days postoperatively. Polysomnography（PSG） and airway CT examination were performed before and 3 months after the surgery. Results:Among the 6 patients, 4 required oxygen therapy preoperatively and 2 required non-invasiveventilatory support. The mean age of patients was 40 days at surgery. The inferior alveolar nerve bundle was not damaged during the operation, and there were no signs of mandibular branch injury such as facial asymmetry after the surgery. Laryngomalacia presented as mixed type: type Ⅱ+ type Ⅲ. The maximum mandibular distraction distance was 20 mm, the minimum was 12 mm, and the mean was 16 mm. The posterior airway space increased from a preoperative average of 3.5 mm to a postoperative average of 9.5 mm. The AHI decreased from a mean of 5.65 to 0.85, and the lowest oxygen saturation increased from a mean of 78% to 95%. All patients were successfully extubated after the surgery, and symptoms of laryngeal obstruction such as hypoxia and feeding difficulties disappeared. Conclusion:Newborns with micrognathia and laryngomalacia have multi-planar airway obstruction. Simultaneous laryngomalacia surgery and mandibular distraction osteogenesis are safe and feasible, and can effectively alleviate symptoms of laryngeal obstruction such as hypoxia and feeding difficulties, while significantly improving the appearance of micrognathia.

Effects of anterior maxillary distraction compared to LeFort-1 osteotomy and total maxillary distraction osteogenesis for treating hypoplastic maxilla in patients with cleft lip and palate- A systematic review and meta-analysis

OBJECTIVE

To compare the treatment outcomes and effectiveness of Anterior Maxillary Distraction (AMD) with the LeFort I Osteotomy and Total Maxillary Distraction Osteogenesis (TMDO) to treat cleft maxillary hypoplasia.

METHODS

(PROSPERO CRD42020223345) Thorough electronic search of seven databases, unpublished gray literature, and a hand search of the relevant studies reference lists was done. Studies assessing mid-facial skeletal, dentoalveolar, and soft-tissue outcomes of AMD in patients >8 years of age, hypoplastic cleft maxilla, and with either TMDO/LeFort 1/ both as control groups were included. Seven included articles were assessed for the study characteristics and qualitative synthesis. Three studies were analyzed quantitatively using the RevMan 5.4 software. The quality of studies was assessed using Cochrane ROB2 and the overall certainty of evidence using GRADE.

RESULTS

AMD was performed in 241 subjects, LeFort 1 in 145 subjects, and TMDO in 42 subjects. Maxillary advancement for AMD and LeFort 1 groups showed no statistically significant difference (Mean Difference, MD -0.64°) while TMDO showed statistically significant advancement than AMD (MD -1.44°). Statistically significant upward rotation of anterior maxilla was noted with AMD (MD -6.15 degrees) than Lefort 1. Upper incisor inclination improved in both AMD and TMDO groups (MD 1.5°). Improvement in the maxilla-mandibular relationship, convexity of face, lip and nose, and marked dentoalveolar changes in overjet and upper incisor position were noted in all the three groups. Discernible airway alterations were noted in LeFort 1 and TMDOs. Total relapse was the least with AMD.

CONCLUSION

Distraction osteogenesis exhibited better dento-skeletal outcomes and minor skeletal relapse than LeFort 1. TMDO is a preferred modality in treating severe maxillary hypoplasia associated with CLP than AMD. Further long-term prospective comparative studies are required, possibly involving the patient-centric merits.

Cleft Palate Repair in Robin Sequence following Mandibular Distraction Osteogenesis Compared to Tongue-Lip Adhesion

OBJECTIVE

To evaluate the timing and safety of cleft palate (CP) repair in patients with Robin sequence (RS) treated with mandibular distraction osteogenesis (MDO) or tongue-lip adhesion (TLA) for airway obstruction.

DESIGN

Retrospective cohort study.

SETTING

Tertiary Pediatric Hospital during 2004-2020.

PATIENTS

148 patients with RS underwent MDO, 66 met inclusion by having MDO and followed by palatoplasty. 26 patients with RS underwent TLA, 14 met inclusion by having TLA and followed by palatoplasty.

MAIN OUTCOME MEASURES

Patient characteristics, hospital/operative details, postoperative complications, and polysomnographic (PSG) data were compared.

RESULTS

Groups were well-matched except more patients with syndromes underwent MDO (N = 27, 41%, P ≤ .002). In the MDO and TLA cohorts, mean CP repair age was 12.8 ± 1.9 months and 14.6 ± 1.6 months, respectively (P ≤ .002). Despite the earlier CP repair in the MDO group, there were no differences in peri-operative complication rates after palatoplasty in either group. All sleep respiratory parameters improved after MDO/TLA prior to palatoplasty P ≤ .050. All PSG parameters remained significantly improved after palatoplasty compared to preoperative values, P ≤ .043. Obstructive apnea hypopnea index and Oxygen saturation nadir further improved after palatoplasty within the MDO group, P ≤ .050, while no changes in the TLA group, P ≥ .500.

CONCLUSIONS

MDO was associated with earlier age at palatoplasty than TLA with a similar perioperative risk profile. In those patients with pre- and post-palatoplasty PSG data, palatoplasty was not associated with a deterioration in PSG parameters, and in fact in the MDO group, PSG data improved.

[Surgical treatment of a patient with mandibular micrognathia accompanied by obstructive sleep apnea syndrome using extended genioplasty]

A method for diagnosing, planning and surgical treatment of patients with micrognathia of the mandible with physiological occlusion is proposed, which makes it possible to objectively assess the severity of the anomaly and concomitant functional disorders of external respiration in the nasopharynx and oropharynx, as well as to identify the pathophysiological mechanisms of obstructive sleep apnea syndrome (OSAS) and develop an optimal surgical treatment plan with high functional and aesthetic results.

[Distraction Osteogenesis for Craniosynostosis]

Distraction osteogenesis is the standard surgical procedure for cranioplasty in children over 6 months of age. This technique carries a risk of detachment of the extender and infection during the course, but such troubles can be reduced by accumulating surgical experience. In addition, furing distraction osteogenesis, the cranium can be sufficiently expanded by slowly stretching the scalp, while adjustment ensures that the facial appearance does not change too much. In this paper, I will explain the surgical technique and postoperative management, focusing on FOA(Fronto-orbital advancement)for trigonocephaly or brachycephaly and BPE(Bilateral parietal expansion)for scaphocephaly. The point of surgery in FOA is the osteotomy of the orbital bar. The osteotomy can be performed safely and easily using a wire saw. The aim of surgery in BPE is to extend an osteotomy up to the front of the coronal suture and down to the part near the cranial floor. This allows improvements of the cranial shape while sufficiently increasing the cranial volume.

[Multidirectional Cranial Distraction Osteogenesis for Craniosynostosis]

In this article we explain in detail the Multidirectional Cranial Distraction Osteogenesis(MCDO)procedure for treating craniosynostosis, in which the multiple cranial bone flaps are pulled up in different directions by the external distractor with the helmet-type frame. MCDO has several advantages over conventional procedures such as unilateral cranial distraction osteogenesis(UCDO). First, the design of the osteotomy in MCDO is flexible depending on the deformities. Each bone flap can be moved to the desired direction in MCDO, while being moved only in one direction along the axis of the distractor in UCDO. This enables remodeling of the deformed cranium to the desired shape. Second, compared with UCDO, the distance between each bone flap after distraction is narrower in MCDO, allowing earlier bone formation and fusion, and thus a shorter consolidation period. Third, the expansion efficacy of MCDO is greater than that of UCDO. The maximum defects of MCDO were the large amount of osteotomy and the resulting heavy bleeding. Therefore, we have recently attempted to improve the design and procedure of osteotomy. The MCDO method allows all phenotypes of skull deformity to be reshaped by distraction osteogenesis.

[Effect of freshening technique on docking site in tibial bone transport management]

OBJECTIVE

To study the effect of freshening technique on docking site in tibial bone transport management.

METHODS

Retrospective cohort study was conducted about the effect of freshening technique on docking site in 20 cases(15 males and 5 females) treated with tibial bone transport from January of 2014 to December of 2019. The age of patients ranged from 19 to 62 years old, with an average of (42.3±11.5)years old. Seven patients had infectious bone defect and 13 patients had non-infectious. Application of freshening technique immediately after docking included resection of invaginated skin or soft tissue, removal of closed sclerotic bone, re-apposition, increasing the contact, acute compression of freshened docking site and grafting from adjacent medullary or bone debris, followed by post-operative gradual compression.

RESULTS

The amount of segmented bone defect ranged from 5 to 15 cm, with an average of(9.2±2.9) cm. Time required from osteotomy to contact of butt end ranged from 26 to 243 days, with an average of(109.1±51.1) days. The duration needed from 3 to 7 months with an average of(3.7±1.1) months before reaching radiological healing criterion in docking site. Fourteen out of 15 concurrent fibular osteotomy were united. Consolidation time for distracted callus ranged from 5 to 28 months, with an average of (15.0±6.5) months. Bone healing index(BHI) ranged from 0.8 to 2.8 months/cm, with an average of (1.6±0.5) months. One surgical site infection (5%) in tibial was noted. No refractures were found in follow-up ranged from 12 to 73 months, with an average of(37.6±20.3) months after fixator removal.

CONCLUSION

Freshening technique immediately after docking had advantages of the shorter healing time, avoidance of refracture, and independance of necessity for remote autograft harvest.

[A retrospective controlled study on the treatment effect of distraction osteogenesis and maxillomandibular advancement for severe obstructive sleep apnea hypopnea syndrome patients]

Objective: To compare the treatment effect of distraction osteogenesis (DO) and maxillomandibular advancement (MMA) for severe obstructive sleep apnea hypopnea syndrome (OSAHS) patients and to guide clinical decisions about treatment of OSAHS. Methods: Thirty-seven OSAHS patients which accepted maxillomandibular advancement (MMA) or distraction osteogenesis (DO) in Stomatological Hospital of the Department of Maxillofacial Trauma and Orthognathic Surgery, School of Stomatology, The Forth Military Medical University from June 2017 to June 2019 were collected. Their preoperative and postoperative data of cephalometry, polysomnography (PSG), Pittsburgh sleep quality index (PSQI) and Epworth sleepiness scale (ESS) scores were collected and analyzed. With propensity score matching method, the treatment effect of MMA and DO was analyzed and compared. Results: According to the statistics of MMA group, only AHI was correlated with operative successful rate and cure rate. With the increase of AHI, the treatment effect of MMA on OSAHS patients gradually decreased. The cut-off point of AHI as a predictor of MMA treatment failure was 78.2 n/h. All the matched cases were severe OSAHS patients. Statistical analysis showed that the mandibular elongation of DO patients[(24.00±4.39) mm] was significantly more than that of MMA group [(11.20±1.37) mm] (t=-6.11, P<0.001), the improvement of PSG index [including lowest oxygen saturation (LSpO₂), longest apnea (LA) and longest hypopnea (LH)] in DO group [LSpO₂=(93.40±1.82)%; LA=(18.28±8.32) s; LH=(61.84±32.94) s] was significantly higher than that in the MMA group [LSpO₂=(86.00±4.06)%, LA=(64.08±21.78) s, LH=(172.40±30.70) s](t=-3.72, P=0.005; t=4.39, P=0.003; t=5.49, P=0.004). The PSQI and the ESS scores of DO group (PSQI=4.20±0.83; ESS=3.40±1.52) were also significantly better than that of MMA group (PSQI=8.80±2.39, ESS=9.40±2.88)(t=4.07, P=0.001; t=4.12, P=0.002). Conclusions: For severe OSAHS patients, the objective and subjective indicators of DO treatment group showed a better therapeutic effect than that of MMA.

Long-term follow-up implant site development in the submerged mandibular primary second molars: A case report

Treatment of ankylosed and submerged primary molars without permanent successors is challenging, as normal vertical dentoalveolar growth is compromised. Thus, grafting techniques and distraction osteogenesis are performed for ridge augmentation before implant restoration. However, these techniques are invasive with limited success. Another treatment for implant site development is noninvasive forced eruption. This case report describes long-term follow-up of alveolar ridge augmentation in the submerged mandibular primary second molars using subluxation and orthodontic forced eruption for implant site development. A 19-year old female had Class II molar relationships, upper anterior crowding with large overjet, missing four second premolars and submerged mandibular primary second molars with inadequate vertical development of alveolar bone. For the vertical alveolar bone alterations in the mandible, forced eruption with subluxation of ankylosed lower primary second molars was applied. Treatment outcome was evaluated over 5 years with stable occlusion, healthy periodontal tissues, and successful radiographic results.

Subcranial Midface Advancement in Patients with Syndromic Craniosynostosis

Patients with syndromic craniosynostosis can present with midface hypoplasia, abnormal facial ratios, and obstructive sleep apnea. These symptoms can all be improved with midface advancement, but it is essential to evaluate the specific morphologic characteristics of each patient's bony deficiencies before offering subcranial advancement. Midface hypoplasia in Crouzon syndrome is evenly distributed between the central and lateral midface and reliably corrected with Le Fort III distraction. In contrast, the midface hypoplasia in Apert/Pfeiffer syndromes occurs in both an axial and a sagittal plane, with significantly more nasomaxillary hypoplasia compared with the orbitozygomatic deficiency.

microRNA-146a mediates distraction osteogenesis via bone mesenchymal stem cell inflammatory response

Distraction osteogenesis (DO) is a widely used surgical technique to repair bone defects, partly owing to its high efficiency in inducing osteogenesis; however, the process of osteogenesis is complex, and the precise mechanism is still unclear. Among the factors identified for an effective DO procedure, well-controlled inflammation is essential. We aimed to explore how microRNA(miR)-146a, a negative regulator of inflammation, influences osteogenesis in DO. First, we established canine right mandibular DO and bone fracture models to evaluate the expression level of miR-146a in response to these procedures. Second, bone marrow mesenchymal stem cells (BMSCs) were isolated from healthy puppies and cultured with lipopolysaccharide (LPS) to observe how inflammation affects osteogenesis. Finally, the osteogenesis activity of BMSCs transfected with lentiviral vector either overexpressing (miR-146a-up) or inhibited for miR-146a expression was evaluated. miR-146a-up-transfected BMSCs were injected locally into the distraction gaps of the DO model canines. On days 42 and 56 post-surgery, the bone volume/tissue volume and bone mineral density values were evaluated via using micro-computed tomography, and newly formed tissues were harvested and evaluated via histological staining. The expression of miR-146a in both the DO canine model and LPS-stimulated BMSCs increased. Overexpression of miR-146a enhanced cell proliferation, migration, and osteogenic differentiation. Additionally, the newly formed callus was improved in canine mandibles injected with miR-146a-up-transfected BMSCs. In summary, miR-146a regulates mandibular DO by improving osteogenesis, and can serve as a potential target to shorten the therapy period of DO.

[Perioperative management and complication control of Le Fort Ⅲ osteotomy in children with syndromic craniosynostosis]

Objective: To summarize the preliminary efficacy, perioperative management and complications of Le Fort Ⅲ osteotomy and midface distraction in patients with syndromic craniosynostosis by retrospective analysis, and to provide clinical experience for reference. Methods: From October 2017 to January 2020, 20 patients with syndromic craniosynostosis underwent Le Fort Ⅲ osteotomy and distraction in The Department of Oral and Maxillofacial Surgery of Peking University International Hospital, including 11 males and 9 females, were involved. The median age was 7 years (1.5 to 15 years). Preoperative risk prevention plan was put forward by multidisciplinary evaluation, and preoperative intervention was carried out. The diagnostic data of SNA, airway volume, polysomnography (PSG), ophthalmology and occlusal relationship were obtained through specialized examination, and osteotomy and distraction surgical plan was formulated through virtual surgical planning. CT was taken 1 week and 3, 6, 12 months after operation, PSG and eye protrudence examination were conducted to evaluate the therapeutic effect, syndrome type, multiple disciplinary treatment (MDT) intervention, occurrence and outcome of complications were summarized. Results: There were 15 cases of Crouzon syndrome and 5 cases of Pfeiffer syndrome. Sleep apnea was the first complaint in 18 cases and exophthalmia in 2 cases. Preoperative interventional therapy included 4 cases of adenoid surgery, 2 cases of continuous positive airway pressure and 2 cases of maxillary expansion. The most common surgical complications were accidental fracture (14/20 cases, 70%), cerebrospinal fluid fistula (2 cases), internal carotid cavernous sinus fistula (1 case), postoperative hyponatraemia (5 cases), crying syndrome (2 cases), wound infection (2 cases), trichiasis of lower eyelid (4 cases), and nasal malformation (1 case). Three cases underwent unplanned secondary surgery. SNA, airway volume and mean percutaneous arterial oxygen saturation (SpO₂) six months after operation were significantly higher than those before operation (F=10.09, P=0.001; F=5.13, P<0.001; F=10.78, P=0.001), and the protrusion and apnea hypopnea index were significantly lower than those before surgery (F=6.73, P=0.010; F=18.47, P<0.001). There were no significant differences in SNA, airway volume, mean SpO₂, ophthalmology between 6 months after surgery and 1 year after surgery (P>0.05). Conclusions: Perioperative safety assessment and early intervention of MDT is an effective diagnosis and treatment model of Le Fort Ⅲ osteotomy and distraction for syndromic craniosynosis. The operative complications are mainly local, and systemic complications are controllable.

In vivo and in silico monitoring bone regeneration during distraction osteogenesis of the mouse femur

BACKGROUND AND OBJECTIVE

Distraction osteogenesis (DO) is a mechanobiological process of producing new bone by gradual and controlled distraction of the surgically separated bone segments. Mice have been increasingly used to study the role of relevant biological factors in regulating bone regeneration during DO. However, there remains a lack of in silico DO models and related mechano-regulatory tissue differentiation algorithms for mouse bone. This study sought to establish an in silico model based on in vivo experimental data to simulate the bone regeneration process during DO of the mouse femur.

METHODS

In vivo micro-CT, including time-lapse morphometry was performed to monitor the bone regeneration in the distraction gap. A 2D axisymmetric finite element model, with a geometry originating from the experimental data, was created. Bone regeneration was simulated with a fuzzy logic-based two-stage (distraction and consolidation) mechano-regulatory tissue differentiation algorithm, which was adjusted from that used for fracture healing based on our in vivo experimental data. The predictive potential of the model was further tested with varied distraction frequencies and distraction rates.

RESULTS

The computational simulations showed similar bone regeneration patterns to those observed in the micro-CT data from the experiment throughout the DO process. This consisted of rapid bone formation during the first 10 days of the consolidation phase, followed by callus reshaping via bone remodeling. In addition, the computational model predicted a faster and more robust bone healing response as the model's distraction frequency was increased, whereas higher or lower distraction rates were not conducive to healing.

CONCLUSIONS

This in silico model could be used to investigate basic mechanobiological mechanisms involved in bone regeneration or to optimize DO strategies for potential clinical applications.

Novel approach to estimate distraction forces in distraction osteogenesis and application in the human lower leg

PURPOSE

In distraction osteogenesis (DO) of long bones, new bone tissue is distracted to lengthen limbs or reconstruct bone defects. However, mechanical boundary conditions in human application such as arising forces are mainly based on limited empirical data. Our aim was the numerical determination of the callus distraction force (CDF) and the total distraction force (TDF) during DO in the tibia of adults to advance the understanding of callus tissue behavior and optimize DO procedures.

METHOD

We implemented a mathematical model based on an animal experiment to enable the calculation of forces arising while distracting callus tissue, excluding the influence of surrounding soft tissue (muscles, skin etc.). The CDF progression for the distraction period was calculated using the implemented model and varying distraction parameters (initial gap, area, step size, time interval, length). Further, we estimated the CDF based on reported forces in humans and compared the results to our model predictions. In addition, we calculated the TDF based on our CDF predictions in combination with reported resisting forces due to soft tissue presence in human cadavers. Finally, we compared the progressions to in vivo TDF measurements for validation.

RESULTS

Due to relaxation, a peak and resting CDF is observable for each distraction step. Our biomechanical results show a non-linear degressive increase of the resting and peak CDF at the beginning and a steady non-linear increase thereafter. The calculated resting and peak CDF in the tibial metaphysis ranged from 0.00075 to 0.0089 N and 0.22-2.6 N at the beginning as well as 20-25 N and 70-75 N at the end of distraction. The comparison to in vivo data showed the plausibility of our predictions and resulted in a 10-33% and 10-23% share of resting CDF in the total resting force for bone transport and elongation, respectively. Further, the percentage of peak CDF in total peak force was found to be 29-58% and 27-55% for bone transport and elongation, respectively. Moreover, our TDF predictions were valid based on the comparison to in vivo forces and resulted in a degressive increase from 6 to 125 N for the peak TDF and from 5 to 76 N for the resting TDF.

CONCLUSION

Our approach enables the estimation of forces arising due to the distraction of callus tissue in humans and results in plausible force progressions as well as absolute force values for the callus distraction force during DO. In combination with measurements of resisting forces due to the presence of soft tissue, the total distraction force in DO may also be evaluated. We thus propose the application of this method to approximate the behavior of mechanical callus properties during DO in humans as an alternative to in vivo measurements.

Mandibular Distraction Osteogenesis for Tongue-Based Airway Obstruction Without Micrognathia

PURPOSE

Mandibular distraction osteogenesis (MDO) effectively treats tongue-based airway obstruction (TBAO) in micrognathic patients with Robin Sequence. Mandibular distraction osteogenesis may also address TBAO in certain nonmicrognathic patients who have severe obstructive apnea, although there is no current literature to guide MDO use in these atypical patients. This study describes outcomes of MDO in a series of patients with TBAO without micrognathia.

METHODS

Patients who underwent MDO for TBAO from 2013-20 were reviewed, and patients with micrognathia were excluded. Study subjects received baseline/follow up polysomnography. Polysomnography variables, including Obstructive Apnea Hypopnea Index, oxyhemoglobin saturation nadir (SpO2 nadir), percent sleep time end tidal CO2 greater than 50 mm Hg (%ETCO2 > 50), and respiratory-related arousals were compared before and after MDO. Demographics, syndromic/cleft palate status, airway anomalies, respiratory support, and feeding outcomes were collected.

RESULTS

One hundred and twenty-four patients underwent MDO during this study period; 5 were nonmicrognathic and included in analysis. Sixty percent (n = 3) of the cohort was syndromic: 1 patient each had Trisomy 9, Beckwith Wiedemann syndrome, and duplicated pituitary gland plus syndrome. Forty percent (n = 2) of patients had a cleft palate, 60% (n = 3) had laryngomalacia, and 40% had tracheomalacia. Median (range) age at MDO was 53 days (47-167 days), and median length of distraction was 16 mm (14-20 mm). After MDO, median Obstructive Apnea Hypopnea Index decreased from x̃ = 60.7/h (11.6-109.4) to x̃ = 5.3/h (3.5-19.3) (P = 0.034). SpO2 nadir increased (69% [58-74] to 85% [80-88], P = 0.011), and median %ETCO2 > 50 mm Hg decreased (5.8% [5.2-30.1] to 0.0% [0.0-1.3], P ≤ 0.043). Continuous positive airway pressure was used by all patients immediately after MDO, and at 6 months postoperatively, 1 patient remained on continuous positive airway pressure and 1 patient required supplemental oxygen. At last follow up, no patients had significant residual airway obstruction or required a tracheostomy.

CONCLUSIONS

Mandibular distraction osteogenesis can effectively treat severe TBAO in some patients without micrognathia that would otherwise be candidates for tracheostomy. When used in select patients, MDO significantly improves obstructive sleep apnea and reduces need for ventilatory support, although feeding support is still needed in most patients at 6 months. Further study in a larger cohort will help identify appropriate candidates for MDO and characterize outcomes of unique patient populations.

[Factors associated with the outcome of maxillary distraction osteogenesis in cleft lip and palate patients]

Since distraction osteogenesis had been used in maxillofacial surgery in the 1990s,it has become an important option for treating maxillary hypoplasia in cleft lip and palate (CLP) patients. Numerous domestic and international studies reported that the prognosis of distraction osteogenesis might be affected by various factors, including the design of osteotomy line, type of distractor, advancement of maxillary bone and the age of patients, etc. Therefore, the present article reviewed possible impact factors that affect the effectiveness and outcomes of maxillary distraction osteogenesis of CLP from three aspects: treatment methods, type of patients and adjuvant therapy, which hopefully might benefit the formulation of treatment strategies in clinical work and improve the prognosis of distraction osteogenesis.

The Surgical Treatment of Brachymetatarsia

This article describes the 3 main surgical options for correction of congenital brachymetatarsia in childhood. The one-stage lengthening by lengthening osteotomy and lengthening with graft interposition are suitable for defects less than 10 mm. For the greater defects from 10 mm to more than 20 mm, gradual lengthening by callus distraction with an external or internal fixator is appropriate. Over the last years, callus distraction with an internal minifixator became commonly established because of the significantly improved aftercare with early full weight-bearing and high postoperative comfort for the child. All 3 surgical procedures are presented with comprehensive image material.

Feeding considerations for infants with craniofacial malformations

Approximately 5% of children experience difficulty with the complex coordination of sucking, swallowing and breathing required for feeding. Infants with craniofacial malformations may have anatomic and neurologic contributions to feeding problems. Examples include cleft lip and/or palate, micrognathia, maxillary hypoplasia, and pharyngeal dysfunction. Interventions may facilitate weight gain and avoid failure-to-thrive in these infants. An interdisciplinary approach to address feeding challenges in children with craniofacial differences is necessary. Positional changes, latching maneuvers, specialized feeder nipples, squeezable bottles, and cup feeding can be implemented early. Surgical intervention, including gastrostomy tube placement, tongue lip adhesion, mandibular distraction osteogenesis and tracheostomy, may be required in more severe cases.

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.

Plate-Tensioned-Nail for Salvage of Failed Subtrochanteric Intramedullary Motorized Limb Lengthening: A Case Report

CASE

A 43-year-old insulin-dependent man with a 4.4-cm posttraumatic femoral limb length discrepancy sustained a subtrochanteric femur fracture associated with failure of a motorized intramedullary limb lengthening nail during distraction osteogenesis. The patient requested a single-stage salvage operation. After implant removal, the femur was stabilized and compressed with a plate-tensioned-nail construct consisting of 4.5-mm locking compression plate tensioned and linked to a femoral reconstruction nail through interlocking screws with immediate weight-bearing.

CONCLUSION

A plate-tensioned-nail construct is a single-stage salvage option for a length-unstable subtrochanteric nonunion which permits immediate full weight-bearing.

Evaluation of osteogenic potential of Cissus quadrangularis on mandibular alveolar ridge distraction

BACKGROUND

This randomized clinical trial was designed to evaluate osteogenic potential of Cissus quadrangularis in alveolar distraction to facilitate implant installation.

MATERIAL AND METHODS

Twenty patients with atrophic ridge were treated by alveolar distraction. After completing distractor activation, patients were randomly divided into two equal groups according to administered drug (placebo and Cissus quadrangularis group). After a consolidation period, distractors were removed and implants were inserted. Clinical evaluation was done to assess wound healing, and distractor and implant stability. Histological evaluation was performed at time of implant insertion. Radiographic evaluation was performed to assess bone volume and density after distraction, as well as, density and bone loss around implant.

RESULTS

Radiographic and histological results showed that bone formation and maturation of study group were faster than that of control group. There was a significant increased bone density in distracted area and around implant in study group than control group. A significant bone loss at end of consolidation period, and around implant at end of the study was reported in control group than study group.

CONCLUSION

Cissus quadrangularis administration during the consolidation period is associated with increased osteogenic potential of distracted bone. The histological and radiographic findings of current study proved that Cissus quadrangularis not only enhances rate of new bone formation, but also bone density to withstand the biomechanical requirements of implant placement in a shorter time. Trial registration This study was retrospectively registered on www.ClinicalTrial.gov : NCT04669795-17\12\2020.

Infant mandibular distraction in absence of ascending ramus: case series

BACKGROUND

Severe microretrognathia with the absence of ascending mandibular ramus is a challenging deformity and treatment must aim to avoid tracheostomy or remove it as soon as possible. Although it is not often reported, mandibular distraction osteogenesis represents a valid treatment option in infants affected by hypoplastic mandible Pruzansky-Kaban type IIb and III.

CASE PRESENTATION

The authors describe 3 cases of infants affected by severe respiratory insufficiency due to congenital mandibular hypoplasia, with follow up ranging from 4 to 8 years. Clinical and technical considerations on treatment choices and outcomes are discussed starting from review of the literature and direct clinical experience.

CONCLUSION

Early mandibular distraction, specifically bidirectional distraction, is an effective and repeatable technique that leads to mandible lengthening with counterclockwise rotation, pogonion projection increase, anteropositioning of the tongue base, and expansion of oropharyngeal volume with positive effect on the respiratory problems of the infant. Even in Treacher Collins patients, known to have a low decannulation rate, all of these elements are essential for effective speech and swallowing therapy and for a subsequent attempt of decannulation.

Overexpressed osteoactivin reduced osteoclastic callus resorption during distraction osteogenesis in mice

Distraction osteogenesis is a widely used surgical technique to treat bone deformity and shortening. Several biological treatments have been studied to enhance bone formation during distraction osteogenesis in animals. However, role of osteoactivin in the osseous tissues during distraction osteogenesis remains poorly understood. In this animal experimental study, we investigated the spatiotemporal expression of osteoactivin by immunohistochemistry and real-time PCR using a mouse model for tibial lengthening. Furthermore, to address the role of osteoactivin in bone lengthening, we subjected the osteoactivin-transgenic mice to distraction osteogenesis model. During the lag phase, the fibroblast-like cells (possible progenitors of the osteoblasts or chondrocytes), which mainly express osteoactivin, were infiltrated into the osteotomy site. Osteoactivin was ubiquitously expressed in the lengthened segment during the distraction and consolidation phases. Consistent with the immunohistochemical analysis, the levels of the osteoactivin transcripts in the tibias were significantly increased throughout the distraction osteogenesis process. The bone mineral content in the osteoactivin-transgenic mice calculated using peripheral quantitative computed tomography was also significantly increased at the remodeling zone. The histomorphometric analysis revealed that newly formed callus resorption in the remodeling zone was significantly reduced but bone formation was not altered in the osteoactivin-transgenic mice. We conclude that osteoactivin functions as an inhibitor of callus resorption during the consolidation phase of distraction osteogenesis.

A novel technique for transportation osteogenesis in a severe maxillary post traumatic defect

Bone maxillary post traumatic defects create significant aesthetic and functional handicaps remaining a critical challenge for surgical reconstruction, among all the alternatives that exist, transportation osteogenesis remains a body ally for having satisfactory results. We present a case of 26 mm of maxillary reconstruction with bifocal transportation osteogenesis using a novel technique, with a custom-made device. At the end of the consolidation period, the patient had clinical formation of new tissue corroborated radiographically. We achieve an adequate dentoalveolar arch, upper lip vestibule, gingiva and palatal fibromucosa similar to the adjacent tissue, improvement of facial contour, labial projection, nostril floors and masticatory function.

Three-dimensional soft tissue evaluation after rapid maxillary expansion and mandibular midline distraction osteogenesis

OBJECTIVES

To evaluate the effects of rapid maxillary expansion (RME) and mandibular midline distraction osteogenesis (MMDO) on facial soft tissues using three-dimensional (3D) images.

MATERIALS AND METHODS

A total of 20 patients (average age 15.86 ± 2.17 years) were treated with RME and MMDO using tooth-borne distractors. Three-dimensional photographs of each patient were taken with a stereophotogrammetry system at baseline (T0), at the end of the distraction period (T1), and at the end of the consolidation period (T2). All data were analyzed using a dependent-samples t-test at a significance level of 5%.

RESULTS

Total and lower face height increased after MMDO (P < .05). Nasal and mouth width increased after RME as compared with baseline (P < .05). The labiomental angle increased at T1 and decreased at T2 (P < .05). After MMDO, the convexity angle increased while the mandibular angle decreased (P < .05). Upper and lower lip angles increased after RME (P < .05). The distance from the lower lip to the E plane increased after MMDO and decreased after RME (P < .05).

CONCLUSIONS

The MMDO and RME procedures provide an efficient nonextraction treatment alternative for transverse maxillomandibular deficiency. MMDO may improve the facial soft tissue profile in the transverse and vertical axis of the mandibular region.

Distraction osteogenesis in craniosynostosis

PURPOSE OF REVIEW

Craniosynostosis, a condition of premature cranial suture fusion, can have significantly detrimental effects on development and growth due to sequelae of increased intracranial hypertension (ICP), exophthalmos, and upper airway obstruction. Evolving surgical treatments now include distraction osteogenesis (DO) due to its many benefits relative to standard cranial vault remodeling procedures. This article provides an overview and update of different surgical applications of DO for patients with craniosynostosis.

RECENT FINDINGS

DO has been utilized successfully for single and multisuture craniosynostosis with or without midface hypoplasia to increase intracranial volume, decrease ICP and improve aesthetics. It has been applied in single suture synostosis, posterior vault DO, fronto-orbital advancement, monobloc DO and Le Fort III DO. DO has been applied through modification of traditional surgical procedures with success in maintaining goals of surgery while reducing risk.

SUMMARY

DO is still a relatively new and evolving surgical technique for patients with syndromic and nonsyndromic craniosynostosis. With promising benefits, consideration for each procedure should be weighed until longer-term data is available.