BACKGROUDS:Developmental dysplasia of the hip (DDH) represents the most prevalent hip disorder in children. A variety of methods for spica cast immobilization have been described using specialized equipment. This study attempts to explore an effective tool for spica cast immobilization. METHODS:We retrospectively analysed a total of 216 children who were diagnosed with DDH and underwent spica cast immobilization in our hospital from January 2018 to December 2023. They were divided into the group A (use of a bamboo stick) and group B (use of the hip spica table). The statistical analysis was conducted on preoperative data, procedure time, and major complications following spica cast immobilization. RESULTS:A total of 101 children in group A and 115 children in group B underwent spica cast immobilization. There was no statistically significant difference in general preoperative data (gender age, weight, medical history, or affected side) and procedure time. The mean number of polymer bandages consumed in group A was 7.8 ± 0.4 rolls, and 7.9 ± 0.5 rolls in group B. There was no statistically significant difference between the two groups. There was no statistical difference in complications (including superficial skin injury, extensive rash, and cast contamination). CONCLUSION:The bamboo stick represents a portable, safe, and cost-effective alternative to the hip plaster operating table. This method can be applied in spica cast immobilization in children.

Abstract Objective: Differentiating septic arthritis from transient synovitis in children is challenging. This study aimed to determine the diagnostic value for distinguishing these two conditions and to develop an effective clinical prediction model based on multi-center clinical data. Methods: We retrospectively analyzed data of children aged under 18 years who were hospitalized in eight specialized children's hospitals in China from 2013 to 2021. To ensure the prediction model's reliability, we established three clinical prediction models. Results: This study collected data of 819 children from 8 tertiary children's hospitals, including 265 patients with septic arthritis and 554 patients with transient synovitis. We established three clinical prediction models. For septic hip arthritis, a retrospective study based on six clinical predictors was a history of prodromal respiratory tract infection (HRTI), temperature>37.5 C, ESR>20 mm/h, CRP>10 mg/L, red blood cell distribution width (RDW)>50%, and WBC>11*109 /L. When these six factors were present, the probability of septic hip arthritis was 99.99%. For septic knee arthritis, a retrospective study based on three clinical predictors, the predictors were ESR>20 mm/h, CRP>10 mg/L, and absolute monocyte count (AMONO)>0.74*109/L. When these three factors were present, the probability of having septic knee arthritis was 94.68%. For septic arthritis (septic hip arthritis or septic knee arthritis), a retrospective study based on six clinical predictors, the predictors were male children, history of HRTI), temperature>37.5C, ESR>20 mm/hr, PC > 407*109/L and CRP>10 mg/L. When these six factors were present, the probability of septic arthritis was 99.65%. Conclusion: This study used multi-center clinical data to construct a new clinical prediction model for children with septic arthritis. In addition we identified new clinical predictors such as sex, history of HRTI, RDW, PC and AMONO. Translational potential: A clinical prediction model, built on multi-center data, is capable of effectively making high-precision predictions for septic arthritis. Furthermore, based on the microbial characteristics of septic arthritis in children, we aim to develop diagnostic kits that can accurately and quickly detect infections caused by pathogens such as bacteria. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Protocols ### Funding Statement This study was supported by Sanming Project of Medicine in Shenzhen (SZSM202011012) and Guangdong High-level Hospital Construction Fund. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee/IRB of Shenzhen Childrens Hospital gave ethical approval for this work(Refnumber:2020091) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data sets used and analysed during the current study are available from these corresponding authors on reasonable request.

Objectives Floating elbow is a rare injury type in pediatric fractures. This study compared the differences in injury mechanisms, treatment modalities, complications and prognosis between floating elbow injury and supracondylar humerus fractures (SHF) in children. Methods The retrospective analysis included patients with floating elbow and SHF treated at our hospital between May 2016 and May 2023. Sex, age, body mass index (BMI), mechanism of injury, affected limb, fracture displacement, presence of neurovascularinjury, type of injury, Gartland classification, and acute compartment syndrome (ACS) were analyzed. Elbow function was evaluated using the Mayo Elbow Performance Score (MEPS). Results A total of 113 children were enrolled, including 27 in the floating elbow group (22 males, 5 females, median age 8 years [interquartile range (IQR) 6–11 years]), and 86 in the SHF group (58 males, 28 females, median age 8 years [IQR 5–10 years]). Mechanism of injury (p = 0.001), fracture type (p = 0.003), and preoperative nerve injury (p = 0.001) differed significantly between the floating elbow and SHF group. ACS incidence differed significantly between open and closed fractures in the floating elbow group (p = 0.028). Conclusion The prognosis of elbow function in children with floating elbow was similar to that in children with SHF. Open fractures resulted in a higher incidence of ACS in floating elbows than in SHF. Level of Evidence: III

Ginsenoside Rg1 is a principal bioactive component of Panax ginseng and Panax notoginseng. Accumulating evidence indicates that ginsenoside Rg1 exerts pro-osteogenic effects; however, the underlying molecular mechanisms related to this function remain elusive. Our previous research demonstrates that leucine-rich repeat-containing G protein-coupled receptor 4 (LGR4) facilitates osteogenic differentiation in mesenchymal stem cells. Nevertheless, the potential association between LGR4 and ginsenoside Rg1 has not been elucidated. In the present study, we investigated the regulatory role of LGR4 in ginsenoside Rg1-induced osteogenic differentiation and delineated the underlying molecular mechanism. First, we validated the pro-osteogenic effect of ginsenoside Rg1 in mesenchymal stem cells. Subsequently, single-cell RNA sequencing was employed to evaluate the involvement of LGR4 in this process. Furthermore, a comprehensive set of experimental approaches was utilized to dissect the interaction between ginsenoside Rg1 and LGR4. Our data demonstrated that ginsenoside Rg1 significantly promoted osteogenic differentiation in mesenchymal stem cells and led to a marked increase in LGR4 and β-catenin. The pro-osteogenic effects of ginsenoside Rg1 were substantially abrogated by either LGR4 or β-catenin knockdown. Mechanistically, ginsenoside Rg1 directly binds to histone deacetylase 1 (HDAC1) and inhibits its acetylation modification. This interaction reduces HDAC1 level while increasing histone H4 lysine 16 acetylation levels, which in turn strengthens Lgr4 expression. Collectively, our findings reveal that ginsenoside Rg1 can activate the Wnt/β-catenin signaling pathway to stimulate osteogenic differentiation, which is mediated by LGR4 up-regulation via HDAC1 deacetylation and H4K16ac hyperacetylation. This study provides a novel mechanistic basis for the application of ginsenoside Rg1 in accelerating bone fracture healing.

This study aimed to investigate the efficacy of partial resection of the sternocleidomastoid muscle (SCM) in the treatment of congenital muscular torticollis (CMT) in children. A total of 149 patients (76 males and 73 females, mean age 3.40 ± 3.58 years) with CMT who underwent partial resection of the SCM at our hospital from December 2011 to July 2021 were retrospectively analyzed, among whom 67 patients presented with right-sided involvement and 82 with left-sided involvement. A total of 109 patients aged 1–4 years were allocated to Group 1, while 40 patients aged 5–16 years were assigned to Group 2. Postoperative efficacy was evaluated using the Cheng and Tang scales, and the average follow-up duration was 5.34 ± 2.43 years. According to the Cheng and Tang scale, 109 patients achieved an excellent score, 34 patients attained a good score, and six patients received a fair score. The operation time was longer in Group 2 than in Group 1 (P < 0.001). Postoperative complications included recurrence in five patients, wound infection in one patient, and hematoma in one patient, whereas no other significant permanent complications occurred in any patient. Our findings demonstrate that partial SCM resection represents an effective treatment option for pediatric CMT.

Osteoporosis, a common orthopedic disease predominantly caused by estrogen deficiency in postmenopausal women, continues to pose a significant public health challenge due to the poorly understood molecular mechanisms. While cuproptosis has been implicated in various pathological conditions, its concrete role in the pathogenesis of osteoporosis remains unknown. Equally ambiguous remains the functional role of Sirtuin 5 (SIRT5), a mitochondrial deacylase with well-characterized involvement in aging and bone formation, in estrogen deficiency-associated osteoporosis. In the present study, we identified a novel potential Estrogen/SIRT5/Ferredoxin 1 regulatory axis that modulates both cuproptosis and the lineage commitment of mesenchymal stem cells. Using an ovariectomized mouse model, we observed that serum copper levels were reduced, whereas copper accumulation was elevated in bone tissue. Estrogen deficiency down-regulated SIRT5 expression, promoted cuproptosis, and induced obvious bone loss. Cuproptosis directly impaired the osteogenic differentiation in mesenchymal stem cells, while SIRT5 overexpression partially rescued this lineage commitment defect. Mechanistically, we showed that estrogen up-regulated SIRT5 expression, which in turn mediated Ferredoxin 1 demalonylation and enhanced its lysosomal degradation. This dual regulatory mechanism may effectively suppress cuproptosis and restore the osteogenic potential of mesenchymal stem cells. Our findings suggest that the novel Estrogen/SIRT5/FDX1 axis may function as a key regulator of bone homeostasis, and identify SIRT5 as a potential therapeutic candidate for postmenopausal osteoporosis, likely through its capacity to reduce the cuproptosis-like features of mesenchymal stem cells.

Background: We sought to investigate whether growth hormone (GH) treatment increases the risk of scoliosis in children with short stature and analyse a dose-response relationship. Methods: A retrospective cross-sectional and cohort study design was used. The cross-sectional study included 1160 children with short stature (355 and 805 in the GH-exposed and non-exposed groups, respectively). The scoliosis prevalence was compared. A total of 313 short stature children without scoliosis at baseline were enrolled in the cohort study (158 and 155, respectively, in the GH and non-GH groups). The median follow-up time was approximately 4.5 years. The relationship between risk factors and GH dose and the occurrence of scoliosis was evaluated with the outcome of new-onset scoliosis. Results: The incidence of scoliosis in the GH exposure group was significantly higher than that in the non-exposure group (5.40% vs. 2.40%, p=0.008). The risk of scoliosis in the GH group was 2.726 times higher than that in the non-GH group (HR=2.726, 95%CI: 1.326-5.605, p=0.006). The total GH dose was positively correlated with scoliosis risk, and there was a dose-response relationship between the total GH dose and the risk (HR=1.002, 95%CI: 1.001-1.003, p<0.001). A dose-response relationship was confirmed, with the predicted probability of scoliosis increasing continuously with cumulative GH dose. Conclusions: GH therapy is an independent risk factor for scoliosis in children with short stature, with a significant dose-response relationship. The cumulative GH dose can be used as a preliminary reference indicator for risk stratification and personalized monitoring.

Traditional paradigms classify prematurity and multiple gestation as risk factors for developmental dysplasia of the hip (DDH). However, recent evidence suggests prematurity may reduce DDH risk via reduced intrauterine mechanical stress. To examine whether prematurity and multiple gestation are independently associated with acetabular morphology in infants referred for Graf ultrasonography. This retrospective cohort study included 5,255 infants (1,230 preterm, 4,025 term) referred for hip ultrasonography from three clinical sources (neonatal ward, child health outpatient clinic, and paediatric orthopaedic clinic) between January 2022 and October 2024. Infants with genetic syndromes, neuromuscular diseases, or congenital malformations were excluded. Abnormal acetabular morphology was defined as Graf ≥IIb using standardised techniques. Three nested multivariable logistic regression models were adjusted for prematurity, sex, multiple gestation, foetal presentation, and delivery mode. Sensitivity analyses verified robustness. Abnormal acetabular morphology frequency was lower in preterm versus term infants (13.3

To solve the difficulty in early differential diagnosis between pediatric osteomyelitis and soft tissue infection (STI), this study aimed to analyze the clinical and ultrasound characteristics of both diseases, screen independent differential risk factors, and explore the correlation between disease course, white blood cell (WBC) count and osteomyelitis risk. A retrospective analysis was performed on 236 pediatric patients (162 cases of osteomyelitis and 74 cases of STI) admitted to a single center from January 2018 to June 2025. Clinical data and ultrasound indicators were collected, and univariate and multivariate logistic regression were used to screen differential factors. Restricted cubic spline (RCS) analysis was applied to explore the nonlinear correlation of key indicators. Compared with the STI group, children with osteomyelitis had significantly longer symptom duration, higher erythrocyte sedimentation rate (ESR), and higher proportions of deep bone tenderness with refusal to bear weight/limp, cortical bone irregularity (CBI), increased periosteal blood flow (IPBF), and subperiosteal abscess (SA) (all P < 0.05). Conversely, the STI group presented with significantly higher levels of white blood cell (WBC), neutrophils, eosinophils, and monocytes. Multivariate logistic regression identified CBI, IPBF, and elevated ESR as independent risk factors for osteomyelitis, while neutrophils and eosinophils were independent protective factors against osteomyelitis. Restricted cubic spline analysis demonstrated that symptom duration and ESR were positively correlated with osteomyelitis risk, and the probability of osteomyelitis decreased significantly when WBC exceeded 12.996 × 10⁹/L. The clinical thresholds of symptom duration > 6 days and WBC > 12.996 × 10⁹/L achieved areas under the receiver operating characteristic curve (AUCs) of 0.617 and 0.579 for differentiating osteomyelitis from STI, respectively. Targeted ultrasound signs combined with clinical indicators can effectively differentiate pediatric osteomyelitis from STI. The nonlinear negative association between WBC and osteomyelitis risk provides a preliminary exploratory clue for clinical bedside rapid diagnosis.

BACKGROUND:Bone cysts are common benign bone tumour-like lesions in children and adolescents. Postoperative wound healing complications significantly affect patient outcomes. Current research primarily focuses on cyst recurrence and bone healing, while studies targeting risk factors for poor postoperative wound healing in children are relatively scarce. METHODS:This single-center retrospective cohort analysis included 99 children with bone cysts who were hospitalized and underwent surgical treatment between January 2021 and September 2025. We analyzed these data in November 2025. Univariate analysis and multivariate logistic regression were used to assess the association of demographic, lesion characteristics and surgery-related variables with poor wound healing. RESULTS:Among the 99 children, 13 (13.1%) experienced poor wound healing. Multivariate analysis revealed that no or single-dose preoperative antibiotic prophylaxis (OR = 9.808, p = 0.031; OR = 34.161, p = 0.010), physeal involvement of the lesion (OR = 7.764, p = 0.023) and operative time ≥90 min (OR = 8.597, p = 0.026) were independent risk factors for poor surgical wound healing. CONCLUSION:Inadequate perioperative antibiotic prophylaxis (either no administration or a single preoperative dose only), physeal involvement of the lesion and prolonged operative time are independent risk factors for poor postoperative wound healing in children. Standardizing antibiotic protocols and identifying high-risk patients based on lesion anatomical characteristics are crucial for reducing the risk of complications.

Osteofibrous dysplasia (OFD) is a rare disease that may lead to tibial lesions. Currently, no gold standard method exists for the treatment of OFD. Recurrence is the most severe complication in OFD. Autogenous iliac bone grafting may reduce postoperative recurrence rates in children with tibial OFD. We aimed to evaluate the clinical effects of subperiosteal hemicortical resection in patients with OFD. We included 21 patients who were diagnosed with OFD. Retrospective clinical data were analyzed from our hospital between November 2009 and October 2016. All the tibial lesions were removed with a subperiosteal hemicortical resection, and bone grafts were implanted. Patient age, sex, symptoms, lesion site, imaging, surgical methods, and histopathological data were analyzed. Local recurrence, postoperative recovery, and postoperative function were evaluated. The postoperative function was evaluated using the Musculoskeletal Tumor Society score (MSTS). OFD recurrence postsurgery occurred in eight patients; seven had no further recurrence after a second procedure, while one patient did not undergo another procedure. There were statistical differences in postoperative recurrence rates between the autogenous and other graft groups ( P = 0.046). The median MSTS was 28 (27–30) and 30 (29.5–30) in the nonautologous ( n = 15) and autologous graft groups ( n = 6), respectively. The function of the nonautologous graft group was significantly worse than that of the autologous group ( P = 0.029). We recommend that patients with tibial OFD undergo subperiosteal hemicortical resection plus autogenous iliac bone grafting. Our study findings showed that these patients experience reduced postoperative recurrence rates and improved prognostic function. Level of Evidence: IV.

BACKGROUND:Glucocorticoid (GC) is the first-line treatment for immune kidney diseases; long-term or excessive use of GC can lead to steroid-induced osteonecrosis of the femoral head (SONFH). We analysed the clinical prognosis and associated factors of SONFH in children with immune kidney disease treated with GC. MATERIALS AND METHODS:We conducted a retrospective analysis at our hospital between January 2012 and December 2022. Clinical data included sex, age, and body weight at the time of the first GC treatment, and GC dose associated with GC treatment. Hip joint function during the last follow-up was used as prognostic outcome. Participants were divided into poor (MDP hip score, <8 points) and medium-excellent groups (9-18 points), and nonparametric test and Spearman correlation analysis were performed. RESULTS:We included 15 children with SONFH. The median age and weight at initial GC treatment were 12.67 (10.75, 14.83) years and 40.00 (37, 50) kg, respectively. The average follow-up time was 4.45 ± 2.54 years, and at last follow-up, 14 patients had bilateral SONFH Nonparametric tests revealed that age at initial GC treatment was older for children with poor hip joint scores (14.83 [12.5-16.4] years) than for those with medium-to-excellent scores (11.50 [10.5-13.8] years) (p = 0.05), and their first-month GC dose (0.127 [0.1-0.2] g) was also higher compared to that of medium-to-excellent group (0.081 [0.0-0.1] g) (p = 0.037); the differences were significant. CONCLUSIONS:SONFH primarily manifests as bilateral onset, and the age at initial GC treatment and first-month GC dose were associated with hip joint prognosis of children with SONFH.

Objective:To investigate the risk factors for steroid-induced osteonecrosis of the femoral head (SONFH) after glucocorticoid (GC) therapy in children with immune kidney diseases. Methods:This retrospective study included patients (1-18 years) diagnosed with immune kidney disease treated with GCs from January 2012 to July 2022 in our hospital. Data, such as sex, age and body weight at the first GC treatment, and the GC dose, were collected. Patients were divided into SONFH and non-SONFH groups based on the occurrence of SONFH. According to the International Classification of Diseases, Tenth Revision, the disease diagnosis was searched on the clinical data webpage of our hospital. The descriptive statistics and binary logistic regression analyses were performed. A nomogram was constructed to predict the risk of SONFH in children with immune kidney disease after GC treatment. The predictive ability of the nomogram was evaluated using the concordance index and calibration plots. Results:The SONFH and non-SONFH groups included 18 and 90 patients, respectively. Age at first GC treatment, 6-month cumulative [oral (po) plus intravenous (iv)] GC dose, total cumulative prednisone (po) dose, total cumulative methylprednisolone (iv) dose for pulse therapy and total cumulative GC (po plus iv) dose significantly differed between the two groups. Age at the initial GC treatment, total cumulative prednisone (po) dose and total cumulative methylprednisolone (iv) dose for pulse therapy were independent risk factors for SONFH in the multivariate analysis. Conclusions:This study identified specific risk factors for developing SONFH during GC treatment. Thus, children with immune kidney disease undergoing GC treatment should be monitored closely based on these risk factors, with the aim to avoid irreversible damage to the femoral head.

Legg–Calvé–Perthes disease (LCPD) is characterized by avascular necrosis of the femoral head (FH) in children. FH blood supply restoration is important for understanding LCPD’s pathophysiology. We used gadolinium-enhanced magnetic resonance imaging (MRI) to clarify the early-stage FH vascular status in patients with stage I Waldenström LCPD. This retrospective study included 23 patients diagnosed with unilateral LCPD using gadolinium-enhanced MRI between January 2017 and September 2024. The vascular evaluation of ossification centers was categorized into visible and invisible levels. Additionally, the axial FH cartilage was classified into medial, lateral, anterior, and posterior parts. Compared with the contralateral normal side, each part’s vascularity on the lesion side was categorized into reduced, comparable, and increased grades. Proportions of grades across parts were compared using Fisher’s exact test with Bonferroni correction. Blood vessel thickness was also assessed. On the affected side, the FH vascular distribution was mainly concentrated within the cartilage, with the ossification center vessels observed in only seven cases. The proportions of patients with increased cartilaginous vessels in the medial, lateral, anterior, and posterior parts were 65.2

BACKGROUND:Elbow fractures are among the most common types of fractures in children; an incision is inevitable when open surgery is performed. Prophylactic antibiotics was widely used in paediatric elbow fractures. This study is to investigate factors associated with postoperative infection in children undergoing open reduction and internal fixation with percutaneous pin fixation of supracondylar humeral fractures (SHFs). All patients did not receive prophylactic antibiotics during perioperative period. METHODS:The clinical data of children with SHF who underwent open reduction and percutaneous pin fixation at our hospital between January 2020 and September 2021 were retrospectively analysed. All patients were divided into no infection (n = 660) and infection (n = 17) groups. Age, sex, duration of surgery, and infection sites were analysed. RESULTS:Open reduction and percutaneous pin fixation were performed in 677 patients with SHFs. The frequency of infection was 2.51% (n = 17). The results of the chi-square test showed that the frequency of infection was significantly related to age (OR = 0.305, 95% CI; 0.106-0.876, p = 0.020) and operation time (OR = 3.731, 95% CI: 1.412-9.859, p = 0.012), but not to sex (OR = 2.440, 95% CI: 0.787-7.561, p = 0.111) or postoperative hospital stay (OR = 1.887, 95% CI: 0.536-6.639, p = 0.464). CONCLUSION:Infection is a rare complication of SHF. Children under 5 years of age with a duration of surgery above 1 h have higher infection rates. Wound and pin care should be strengthened to reduce the risk of postoperative infection. LEVEL OF EVIDENCE:III.

BACKGROUND:Calcium gluconate is widely used to treat neonatal hypocalcemia, severe hyperkalemia, and convulsions. However, extravasation of calcium gluconate can lead to iatrogenic calcinosis, causing symptoms such as local redness and swelling, cutaneous plaque, soft tissue calcification, and cutaneous tissue necrosis. Therefore, this study retrospectively analyzed the conservative treatment results of neonatal iatrogenic calcinosis. METHODS:Data of neonates diagnosed with iatrogenic calcinosis cutis caused by calcium gluconate exudation between December 2012 and June 2021 were analyzed retrospectively. The clinical data included medical history, physical examination, laboratory findings, and radiographs. All the patients were conservatively treated, and the curative effect and prognosis were followed up by evaluating radiographs and limb function. Patients with complications, such as recurrence or limb dysfunction, were further followed up. RESULTS:Overall, 16 neonates (sex: 10 male and 6 female infants; age: 17.5 ± 7.8 days) were included. Iatrogenic calcinosis cutis was located around the left wrist, right wrist, left ankle, and right ankle in four, one, six, and five patients, respectively. Calcification healed within 1-3 months (mean: 1.6 ± 0.6 months). After a follow-up of 0.5-8.5 years (mean: 3.5 ± 2.8 years), the appearance, joint function, local growth, and development of the lesion of the neonates with iatrogenic calcinosis cutis were consistent with those of the healthy ones. CONCLUSION:For neonatal iatrogenic calcinosis cutis without cutaneous and subcutaneous tissue necrosis, symptomatic support treatment is effective and does not affect the limbs' appearance and function.Level of evidence: IV.

Bone defects and non-union are prevalent in clinical orthopedy, and the outcomes of current treatments are often suboptimal. Bone tissue engineering offers a promising approach to treating these conditions effectively. Bone morphogenetic protein 9 (BMP9) can commit mesenchymal stem cells to osteogenic lineage, and a knowledge of the underlying mechanisms may help advance the field of bone tissue engineering. Leucine-rich repeats containing G protein-coupled receptor 4 (LGR4), a member of G protein-coupled receptors, is essential for modulating bone development. This study is aimed at investigating the impact of LGR4 on BMP9-induced osteogenesis in mesenchymal stem cells as well as the underlying mechanisms. Bone marrow stromal cells from BMP9-knockout mice exhibited diminished LGR4 expression, and exogenous LGR4 clearly restored the impaired osteogenic potency of the bone marrow stromal cells. Furthermore, LGR4 expression was increased by BMP9 in C3H10T1/2 cells. LGR4 augmented the benefits of BMP9-induced osteogenic markers and bone formation, whereas LGR4 inhibition restricted these effects. Meanwhile, the BMP9-induced lipogenic markers were increased by LGR4 inhibition. The protein levels of Raptor and p-Stat3 were elevated by BMP9. Raptor knockdown or p-Stat3 suppression attenuated the osteoblastic markers and LGR4 expression brought on by BMP9. LGR4 significantly reversed the blocking effect of Raptor knockdown or p-Stat3 suppression on the BMP9-induced osteoblastic markers. Raptor interacts with p-Stat3, and p-Stat3 activates the LGR4 promoter activity. In conclusion, LGR4 boosts BMP9 osteoblastic potency in mesenchymal stem cells, and BMP9 may up-regulate LGR4 via the mTORC1/Stat3 signal activation.

Background:The shape of the labrum is strongly correlated with outcomes of developmental dysplasia of the hip (DDH). Magnetic resonance imaging (MRI) is the generally preferred imaging technique for observing the labrum.Purpose:We aimed to find a correlation between the labrum shape and anterior-posterior (AP) pelvic measurements in children with DDH.Methods:Preoperative AP pelvic x-ray radiographs and MRI of patients with DDH from January 2019 to December 2021 were retrospectively collected and divided into three groups by labrum shape on MRI: everted, partly inverted, and inverted. The acetabular length ratio (RAL) in patients with unilateral DDH and the ratio of acetabular length to interpedicular distance (RALI) in all patients were calculated. T-tests were used to analyze differences between the groups. Receiver operating characteristic curve (ROC) analysis was performed between the everted group and the partly inverted and inverted groups.Results:We found significant differences in RAL between the everted and partly inverted groups, everted and inverted groups, and everted and combined groups. The ROC analysis showed that the best cutoff value for RAL was 0.945 between the everted and combined groups, with an area under the curve (AUC) of 88.4%. The sensitivity at the best RAL value was 0.783, and the specificity was 0.887. Moreover, we observed a significant difference in RALI between the everted, partly inverted, and inverted groups, as well as between the everted and combined groups. The optimal cutoff value for RALI between the everted and combined groups was 0.575, with an AUC of 74.5%. The sensitivity at the best RALI value was 0.765, and the specificity was 0.674.Conclusion:The RAL or RALI values on pelvic AP radiographs can be used to predict the shape of the labrum.Level of Evidence:III.

Elastic stable intramedullary nailing (ESIN) internal fixation is used clinically to treat pathological fractures of bone cysts in children. However, one of the most important complications was removal difficulty. In this study, we aim to analyse the factors which can influence ESIN removal in healed bone cysts in children. From April 2014 to November 2020, the clinical data of 49 children who underwent elastic stable intramedullary nail removal for pathological fractures of the bone cysts in our hospital were retrospectively analysed. The following data, including age, sex, pathological fracture site, with bone graft, number of ESINs, ESIN indwelling time, and extraosseous length of ESIN were collected, and univariate analysis and logistic regression analysis was performed. The frequency of difficulty in ESIN extraction was 44.90% (22/49). The univariate logistic regression analysis showed that age,ESIN indwelling time,with bone garft and extraosseous length of ESIN may be correlated with the difficulty in removing ESIN (P < 0.05), while sex, pathological fracture site, number of ESIN may not be correlated with the difficulty in removing ESIN (P > 0.05).The multivariate logistic regression analysis showed that the ESIN indwelling time was the independent influencing factor for difficulty in removing ESIN (P < 0.05). The factors influencing the ESIN removal in healed bone cysts in children include over 11.79 years old, the long indwelling time of the ESIN(over 10.5 months),with bone graft and short extraosseous length of ESIN(≤ 0.405 cm). These factors influencing ESIN removal in healed bone cysts in children should be considered.

Humeroradial joint fixation (HJF) has been employed during elbow surgery to maintain stability. Kirschner wire (K-wire) fixation is the most commonly used method in children; however, there are valid concerns regarding complications such as breakage. In this study, we retrospectively analyzed the safety of humeroradial fixation using K-wires in children. In total, 249 patients diagnosed with Monteggia fractures underwent HJF at our institute from January 2013 to November 2021. All relevant clinical data were collected after applying the inclusion and exclusion criteria. Skin irritation, incision infection, elbow instability, and ulnar healing were followed up. The elbow function was evaluated using Mackay standards. There were 81 females and 168 males (average age, 6.6 ± 2.8 years). Of these patients, 67 did not have ulna fixation, whereas 127 were fixed with K-wires after osteotomy of the proximal ulna or correction of the deformity. The K-wire sizes used for HJF were 1.6, 1.8, and 2 mm in 6, 125, and 118 patients, respectively. The duration of K-wire fixation of the humeroradial joint was 6.6 ± 2.5 weeks on average. Two patients suffered from K-wire breakage and underwent reoperation. There were three patients with K-wire end irritation. According to Mackay standards, the elbow function score was excellent, good, and poor in 188, 41, and 20 patients, respectively, at 6 months postoperatively. No bone bridge was found at the capitellum and radial head fixation sites in any patient. HJF using K-wires combined with a cast is a safe method with a low incidence of complications in children and should be considered a reliable option when humeroradial joint fixation is required. LEVEL OF EVIDENCE: IV.