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Abstract BACKGROUND There is no agreement on frequency of distractions of magnetically controlled growing rods (MCGRs) but more frequent and smaller amounts of distractions mimic physiological spine growth. The mid- to long-term follow-up and management at skeletal maturity is unknown. OBJECTIVE To analyze patients with mean 6 yr of follow-up and describe the fate of MCGR graduates. METHODS Early onset scoliosis (EOS) patients treated with MCGRs with minimum 4 yr of follow-up and/or at graduation were studied. Parameters under study included Cobb angle, spine and instrumented lengths, and rod distraction gains. Relationship between timing of rod exchanges with changes in rate of lengthening was studied. RESULTS Ten EOS patients with mean 6.1 yr of follow-up were studied. The greatest Cobb angle correction occurred at the initial implantation surgery and was stable thereafter. Consistent gains in T1-12, T1-S1, and instrumented segment were observed. Rate of lengthening reduced after the first year of use but improved back to initial rates after rod exchange. Seven of the ten patients experienced complications with reoperation rate of 40% for rod distraction failure and proximal foundation problems. Only mild further improvements in all radiological parameters were observed pre- and postfinal surgery. No clinically significant curve progression was observed for rod removal only. All postfinal surgery parameters remained similar at postoperative 2 yr. CONCLUSION This study provides an outlook of the end of MCGR treatment. Although this is a fusionless procedure, instrumented segments do experience stiffness limiting further correction and length gain during final surgery whether fusion or rod removal is performed.

Background Distraction osteogenesis (DO) enables gradual bone elongation through controlled osteotomy and distraction. Existing radiographic and index-based assessments face limitations. Callus pattern classification offers predictive value, but its early applicability across age groups and gap lengths remains unclear. Methods We retrospectively reviewed 129 patients (155 bone segments) who underwent lower limb DO between 2003 and 2023. Patients had a mean age of 37.3 years (5.6–77). The mean distraction length was 53.2 mm (11–174). Radiographs were graded monthly using modified Li classification, depicting two callus consolidation routes: Route 1 (no presence of type 5/8) and Route 2 (presence of type 5/8). Patients were stratified by age (younger: < 25 years; middle: 25–49 years; older: 50 years) and distraction length (shorter: < 5 cm; longer: 5 cm). Outcome measures included parameters such as distraction-consolidation time (DCT), healing index (HI), etc., compared by Mann–Whitney test and analysis of variance. Trends of radiographic progress were analyzed by Loess regression. Results Route 1 demonstrated favorable healing with significantly lower DCT (300.4 vs 381.6 days; p  = 0.002) and HI (70.1 vs 89.1 days/cm; p  = 0.021). Younger age patients showed negligible differences between two routes. However, middle and older age groups showed delayed consolidation in Route 2, particularly from the high-intermediate callus density grades, Li classification type 6 and 7, onward ( p  < 0.05). Long distraction gaps further amplified route-based divergence in the trajectory of consolidation. Conclusion Evolution of callus patterns closely correlate with outcomes of DO. Negative patterns (types 5/8) are associated with delayed healing, particularly in older patients and those with longer distraction lengths. These findings support their use as a timely marker for risk stratification and suggest heightened surveillance or protocol adjustment, such as slowdown of distraction, cyclic distraction-compression dynamization, or additional fixation methods, to optimize outcomes. Level of evidence Level III, retrospective cohort study.

Purpose The aim of this study was to compare the efficacy, clinical outcomes, and complications of cable-asisted bone transport (CASt) and circular external fixator-assisted bone transport (CEFt) methods in the management of bone defects of the tibia. Methods A retrospective analysis was conducted on 32 patients who underwent segmental bone transport for tibial bone defects between January 2006 and January 2020 and met the study inclusion criteria. Patients were categorized into two groups: CASt group ( n  = 16) and CEFt group ( n  = 16). The primary outcome measures included radiological parameters (External Fixator Index (EFI), Radiological Consolidation Time (RCT), and Radiological Consolidation Index (RCI)), functional independence (Lower Extremity Functional Index, LEFI) and functional outcomes (ASAMI Bone and Functional Scores). Secondary outcomes included pain levels (Visual Analog Scale, VAS), and complication rates (Paley’s and Checketts-Otterburn classifications). Results The CASt method resulted in significantly reduced pain scores during distraction (VAS: 4.81 ± 0.98 vs. 6.75 ± 0.86; p  = 0.001). Pin-tract infection rates were significantly lower in the CASt group compared to the CEFt group (50% vs. 93.8%; p  = 0.013). There was no significant difference between the groups in radiological (EFI, RCT, RCI) and functional outcomes (ASAMI scores) ( p  > 0.05). Conclusion Both CASt and CEFt methods are effective and reliable options in the management of bone defects of the tibia. However, CASt offers advantages such as lower pin-tract infection rates and less pain during distraction, resulting in greater patient comfort and compliance. Given its less invasive nature, CASt may be preferable in patients at higher risk of infection or with a low pain threshold. However, the technical complexity of this method requires experienced surgical application.

Trans-sutural distraction osteogenesis has been proposed as an alternative technique of craniofacial remodelling surgery for craniosynostosis correction. Many studies have defined the contribution of a series of biological events to distraction osteogenesis, such as changes in gene expression, changes in suture cell behaviour and changes in suture collagen fibre characteristics. However, few studies have elucidated the systematic molecular and cellular mechanisms of trans-sutural distraction osteogenesis, and no study has highlighted the contribution of cell–cell or cell–matrix interactions with respect to the whole expansion process to date. Therefore, it is difficult to translate largely primary mechanistic insights into clinical applications and optimize the clinical outcome of trans-sutural distraction osteogenesis. In this review, we carefully summarize in detail the literature related to the effects of mechanical stretching on osteoblasts, endothelial cells, fibroblasts, immune cells (macrophages and T cells), mesenchymal stem cells and collagen fibres in sutures during the distraction osteogenesis process. We also briefly review the contribution of cell–cell or cell–matrix interactions to bone regeneration at the osteogenic suture front from a comprehensive viewpoint.

Background Distraction osteogenesis (DO) is an effective but lengthy procedure to fully induce bone regeneration in large bone defects. Accumulating evidence supports the role of exosomes secreted by endothelial progenitor cells (EPC-Exos) in stimulating angiogenesis, which is closely coupled with osteogenesis. This study aimed to investigate whether EPC-Exos promote bone regeneration during DO in rats. Methods Exosomes were isolated from the supernatants of rat bone marrow EPCs via ultracentrifugation and characterized via transmission electron microscopy, tunable resistive pulse sensing analysis, and western blot analysis. Unilateral tibial DO models were generated using 68 Sprague-Dawley rats with a distraction rate of 0.5 mm per day for 10 days. After local injection of EPC-Exos into the distraction gaps after distraction, the therapeutic effects of EPC-Exos on bone regeneration and angiogenesis were assessed via X-ray, micro-computed tomography (micro-CT), and biomechanical and histological analyses. Pro-angiogenic effects and the potential mechanism underlying the effects of EPC-Exos on human umbilical vein endothelial cells were subsequently evaluated via in vitro assays including Cell Counting Kit-8, wound healing, tube formation, and western blot assays. Results EPC-Exos were spherical or cup-shaped vesicles ranging from 50 to 150 nm in diameter and expressed markers including CD9, Alix, and TSG101. X-ray, micro-CT, and histological analyses revealed that bone regeneration was markedly accelerated in rats treated with EPC-Exos. The distracted tibias from the Exos group also displayed enhanced mechanical properties. Moreover, vessel density was higher in the Exos group than in the control group. In addition, in vitro analyses revealed that EPC-Exos enhanced the proliferation, migration, and angiogenic capacity of endothelial cells in an miR-126-dependent manner. Further, EPC-Exos downregulated SPRED1 and activated Raf/ERK signaling. Conclusions The present results show that EPC-Exos accelerate bone regeneration during DO by stimulating angiogenesis, suggesting their use as a novel method to shorten the treatment duration of DO.

Purpose The task faced by surgeons becomes significantly more challenging when they encounter lower extremity bone defects due to a variety of causes requiring lengthening. The most discussed and successful approach is the Illizarov technique, or lengthening over a nail (LON):distraction osteogenesis is also widely performed with monoliteral external fixators and intramedullarylengthening nails have increasingly been used in the last decade. Methods The data were collected from PubMed, Cochrane Library, Embase, and the Web of Science for all available studies comparing the outcomes of Ilizarov technique alone and LON technique (from January 1, 1997, to November 30, 2023). The outcomes of interest encompassed the external fixation index (EFI) (month/cm), mean duration of follow-up (MFT) (month), length gained (LG) (cm), consolidation index (CIx) (month/cm), and bone healing index (BHI) (month/cm).Complications include pin tract infection rate (PTI), axial deviation rate (AD), occurrence of intramedullary infection (II), delayed consolidation rate (DC), as well as data categorized into three levels of problems, obstacles, and sequelae based on the severity of complications.Two reviewers independently assessed each study for quality and extracted data. The case–control or respective cohort studies were evaluated using the Newcastle–Ottawa scale (NOS) to determine their techniqueological rigor.The Cochrane Collaboration’s risk assessment tool was employed to perform quality evaluations for randomized controlled trials. Results This review included thirteen studies comprising a total of 629 patients.The external fixation index (month/cm) was significantly smaller in the LON technique compared to the Ilizarov technique alone [Mean Difference(MD) = -29.59, 95% CI -39.68–-19.49, P  < 0.00001].In terms of the mean follow-up time(month) (MD = -0.92, 95% CI -3.49–1.65, P  = 0.57), length gained (cm) (MD = -0.87, 95%CI -2.80–1.07, P  = 0.38), consolidation index (month/cm) (MD = 0.66, 95% CI -3.44–4.77, P  = 0.75), and bone healing index (month/cm) (MD = -3.33, 95% CI -13.07–6.41, P  = 0.5), there were no significant differences observed. The LON technique exhibited a lower incidence of axial deviation [Odds Ratio(OR) = 0.06, 95%CI 0.03–0.16, P  < 0.00001] and pin tract infection (OR = 0.30, 95%CI 0.18–0.50, P  < 0.00001) compared to the Ilizarov technique alone.The remaining complications, such as intramedullary infection rate (OR = 0.93, 95%CI 0.42–2.06, P  = 0.85) and delayed consolidation rate(OR = 0.61, 95%CI 0.20–1.86, P  = 0.38), did not exhibit statistically significant differences.Our findings demonstrated that the LON technique results in lower incidences of problems (38.5%vs.58.6%) and sequelae (16.6% vs.30.9%) when compared to the Ilizarov technique alone. However, the rates of obstacles (32.4% vs.32.3%) were comparable between the two methods. Conclusions Our findings indicate that patients treated with the LON technique experienced significantly shorter external fixation durations and a lower incidence of complications (e.g., pin tract infections and axial deviation) compared to those treated with the Ilizarov technique alone. Other outcome metrics showed no significant differences between the two techniques. However, the LON technique offers substantial benefits, including reduced external fixation times and increased comfort, which enhance patient compliance. In conclusion, the LON technique is a safe, reliable, and effective method for treating tibial and femoral defects.

ObjectiveDistraction osteogenesis maxillary expansion (DOME) is a reliable method to expand the nasal floor and hard palatal vault in adults with obstructive sleep apnea (OSA). DOME results in a reduction in the apnea-hypopnea index (AHI) and subjective report of improved nasal breathing. Using rhinomanometry augmented computational fluid dynamic (CFD) modeling, we propose a mechanism of how DOME reduces upper airway pharyngeal collapse in adults with OSA.Material and methodA retrospective cohort with 20 subjects and mean age of 29.6 ± 8 years who completed DOME at Stanford University from September 2014 to April 2016. Subjects were included if polysomnography, airway morphology, and rhinomanometry were available for use. From the CBCT data, 3D nasal and pharyngeal airway model were generated. Numeric CFD simulation of the airway models were analyzed under the following conditions: (1) the volume of air was flowing at a velocity of 300 cm3/s, (2) the wall surface was not slippery, and (3) the simulations were repeated 1000 times to calculate mean values. Statistical analyses using SPSS v24 software included paired t tests, nonparametric Wilcoxon rank test, Friedman test with Bonferroni correction, and Spearman’s correlation coefficients (p < 0.05).ResultsMean AHI improved from 17.8 ± 17.6 to 7.8 ± 7.1 events per hour (p < 0.001). Mean lowest oxygen saturation improved from 88.2 ± 7.2 to 90.9 ± 4.2% (p < 0.05). Mean airflow velocity within the nasal airway decreased from 15.6 ± 7.3 to 7.4 ± 2.1 m/s (p < 0.001) after DOME. Mean negative pressure of the nasal airway, retropalatal airway, oropharyngeal airway, and hypopharyngeal airway is reduced from − 158.4 ± 115.3 to − 48.6 ± 28.7 Pa, from − 174.8 ± 119.9 to − 52.5 ± 31.3 Pa, from − 177.0 ± 118.4 to − 54.9 ± 31.8 Pa and from − 177.9 ± 117.9 to − 56.9 ± 32.1 Pa (p < 0.001), respectively. AHI positively correlated with nasal flow velocity (p < 0.05) and negatively correlated with pharyngeal airway pressure (p < 0.05). ODI was positively correlated with nasal velocity (p < 0.05) and negatively correlated with nasal airway pressure (p < 0.05), retropalatal airway pressure (p < 0.001), oropharyngeal airway pressure (p < 0.001), and hypopharyngeal airway pressure (p < 0.05).ConclusionAnatomic expansion of the nasal floor with widening of the hard palatal vault from DOME is associated with reduction of nasal airflow velocity and downstream reduction of negative pressure in the pharyngeal airway. This dynamic interaction correlates with a reduction in the apnea-hypopnea index (AHI) and Oxygen Desaturation Index (ODI).

Background Previous designs of internal bone lengthening devices have been fraught with imprecise distraction, resulting in nerve injuries, joint contractures, nonunions, and other complications. Recently, a magnet-operated PRECICE ® nail (Ellipse Technologies, Inc, Irvine, CA, USA) was approved by the FDA; however, its clinical efficacy is unknown. Questions/purposes We evaluated this nail in terms of (1) accuracy and precision of distraction, (2) effects on bone alignment, (3) effects on adjacent-joint ROM, and (4) frequency of implant-related and non-implant-related complications. Methods We reviewed medical and radiographic records of 24 patients who underwent femoral and/or tibial lengthening procedures using the PRECICE ® nail from August 2012 to July 2013 for conditions of varied etiology, the most common being congenital limb length discrepancy, posttraumatic growth arrest, and fracture malunion. This group represented 29% of patients (24 of 82) who underwent a limb lengthening procedure for a similar diagnosis during the review period. At each postoperative visit, the accuracy and precision of distraction, bone alignment, joint ROM, and any complications were recorded by the senior surgeon (SRR). Accuracy reflected how close the measured lengthening was to the prescribed distraction at each postoperative visit, while precision reflected how close the repeated measurements were to each other over the course of total lengthening period. No patients were lost to followup. Minimum followup from surgery was 3 weeks (mean, 14 weeks; range, 3–29 weeks). Results Mean total lengthening was 35 mm (range, 14–65 mm), with an accuracy of 96% and precision of 86%. All patients achieved target lengthening with minimal unintentional effects on bone alignment. The knee and ankle ROM were minimally affected. Of the complications requiring return to the operating room for an additional surgical procedure, there was one (4%) implant failure caused by a nonfunctional distraction mechanism and six (24%) non-implant-related complications, including premature consolidation in one patient (4%), delayed bone healing in two (8%), delayed equinus contracture in two (8%), and toe clawing in one (4%). Conclusions We conclude that this internal lengthening nail is a valid option to achieve accurate and precise limb lengthening to treat a variety of conditions with limb shortening or length discrepancy. Randomized, larger-sample, long-term studies are required to further confirm clinical efficacy of these devices, monitor for any late failures and complications, and compare with other internal lengthening devices with different mechanisms of operation. Level of Evidence Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Fracture healing and distraction osteogenesis have important applications in orthopedic, maxillofacial, and periodontal treatment. In this review, the cellular and molecular mechanisms that regulate fracture repair are contrasted with bone regeneration that occurs during distraction osteogenesis. While both processes have many common features, unique differences are observed in the temporal appearance and expression of specific molecular factors that regulate each. The relative importance of inflammatory cytokines in normal and diabetic healing, the transforming growth factor beta superfamily of bone morphogenetic mediators, and the process of angiogenesis are discussed as they relate to bone repair. A complete summary of biological activities and functions of various bioactive factors may be found at COPE (Cytokines & Cells Online Pathfinder Encyclopedia), http://www.copewithcytokines.de/cope.cgi.

Background The purpose of this study was to report the clinical and psychological outcomes of using a locking compression plate (LCP) as a sequential external fixator following the distraction phase in the treatment of tibial bone defects caused by fracture-related infection (FRI). Methods We retrospectively analyzed the clinical records and consecutive X-ray images of patients with tibial bone defects who were treated with an LCP as a sequential external fixator following the distraction phase, between June 2017 and December 2022. The ASAMI criteria were applied to assess the bone and functional outcomes, and postoperative complications were evaluated by using the Paley classification. The SCL-90-R questionnaire was used to evaluate patients’ psychological symptoms, documented and compared at Time 1 (before bone transport), Time 2 (after distraction phase), and Time 3(final follow-up). Statistical significance was set at P  < 0.05. Results This study included 22 participants with a mean age of 37.72 ± 9.65 years, comprising 17 males (77.2%) and 5 females (22.7%). The mean postoperative follow-up time was 29 ± 2.65 months. The mean number of previous surgical interventions per patient was 5.22 ± 1.26. Twenty-two patients with tibial bone defects caused by FRI were successfully treated using an LCP as a sequential external fixator following the distraction phase, with a mean bone union time of 9.95 ± 1.52 months. Bone union was achieved in all cases (100%) without the use of bone grafts at the docking sites. Following the completion of distraction, the Ilizarov apparatus or monorail fixator was retained for an additional 2.20 ± 0.53 weeks before being exchanged for the external locking compression plate (ELCP). The mean external fixation time (EFT) was 12.29 ± 1.67 months, with a mean external fixation index (EFI) of 1.83 ± 0.22 month/cm (Table 2). At the final follow-up, bone and functional outcomes were evaluated using the ASAMI criteria. Bone outcomes included 10 excellent and 12 good results, while functional outcomes included 12 excellent, 9 good, and 1 fair result. Statistically significant differences in psychological impacts were observed among the three time points (Time 1 vs. Time 2, P  = 0.034; Time 2 vs. Time 3, P  = 0.020; Time 1 vs. Time 3, P  = 0.012). Complications were observed in 6 patients (27.2%), including joint stiffness ( n  = 3), pin-track infection ( n  = 3), and refracture ( n  = 1). All complications were successfully managed. Conclusion LCP used as a sequential external fixator following the distraction phase is an effective method for treating massive tibial bone defects caused by FRI and is also suitable for patients with scars and poor tissue conditions resulting from multiple previous debridement. Furthermore, this combined technique could be more beneficial in alleviating psychological burdens, supporting patients’ engagement in rehabilitation, and facilitating a return to normal life. Clinical trial number Not applicable.