BACKGROUND:With the increasing demand for orthopedic implants,the search for materials with good biocompatibility and degradability has become a research hotspot.Magnesium-lithium-gadolinium(Mg-Li-Gd)alloy has good degradability,biocompatibility,and mechanical properties,providing ideal supporting conditions for fracture healing.OBJECTIVE:To evaluate the effects of Mg-Li-Gd alloy implants on bone healing in rats.METHODS:A circular half-defect model was made on the lateral side of the right mid-femoral segment in 28 SD rats,and the rats were randomly divided into two groups.The stainless steel group was fixed with a stainless steel intramedullary nail,and the magnesium alloy group was fixed with an Mg-Li-Gd alloy intramedullary nail,with 14 rats in each group.At 2,8,and 14 weeks after surgery,right femur X-ray and Micro-CT examinations,as well as hematoxylin-eosin staining,immunohistochemical staining,and western blot assay were performed.RESULTS AND CONCLUSION:(1)X-ray film:At 2 weeks after surgery,the osteotomy lines of both groups were clear,the density of the intramedullary nail in the magnesium alloy group was close to that of bone tissue,and the density of the intramedullary nail in the stainless steel group was higher than that of bone tissue.At 8 weeks after surgery,the osteotomy lines of both groups were blurred,and the intramedullary nail in the magnesium alloy group had corroded and degraded.At 14 weeks after surgery,the osteotomy lines of both groups disappeared,and the intramedullary nail in the magnesium alloy group further corroded and degraded.(2)Micro-CT:At 2 weeks after surgery,callus began to form in both groups;8 weeks after surgery,the stainless steel group entered the callus remodeling stage,and a relatively dense bone structure was formed at the bone defect site,and the magnesium alloy group showed obvious callus hyperplasia at the bone defect site.At 14 weeks after surgery,the stainless steel group showed a mature bone remodeling process,and thick cortical bone was formed at the bone defect site,and thinner cortical bone was formed in the magnesium alloy group.(3)Hematoxylin-eosin staining:At 2 weeks after surgery,a large number of osteoblasts,osteocytes,a small number of osteoclasts and trabecular structures were observed in the magnesium alloy group,while relatively few osteoblasts and osteocytes were observed in the stainless steel group.At 8 weeks after surgery,a large number of osteoblasts,osteocytes,and mature trabecular structures were observed in the magnesium alloy group,while a large number of osteocytes and lamellar bones were observed in the stainless steel group.At 14 weeks after surgery,lamellar bones were observed in the magnesium alloy group,while mature bone tissue was observed in the stainless steel group.(4)Immunohistochemical staining and western blot assay:At the same time point,the expression levels of bone morphogenetic protein 2,osteocalcin,and RUNX2 proteins in the magnesium alloy group were higher than those in the stainless steel group.(5)The results showed that compared with stainless steel materials,Mg-Li-Gd alloy had no obvious advantage in promoting the formation of fracture healing structure.

BACKGROUND:With the increasing demand for orthopedic implants,the search for materials with good biocompatibility and degradability has become a research hotspot.Magnesium-lithium-gadolinium(Mg-Li-Gd)alloy has good degradability,biocompatibility,and mechanical properties,providing ideal supporting conditions for fracture healing.OBJECTIVE:To evaluate the effects of Mg-Li-Gd alloy implants on bone healing in rats.METHODS:A circular half-defect model was made on the lateral side of the right mid-femoral segment in 28 SD rats,and the rats were randomly divided into two groups.The stainless steel group was fixed with a stainless steel intramedullary nail,and the magnesium alloy group was fixed with an Mg-Li-Gd alloy intramedullary nail,with 14 rats in each group.At 2,8,and 14 weeks after surgery,right femur X-ray and Micro-CT examinations,as well as hematoxylin-eosin staining,immunohistochemical staining,and western blot assay were performed.RESULTS AND CONCLUSION:(1)X-ray film:At 2 weeks after surgery,the osteotomy lines of both groups were clear,the density of the intramedullary nail in the magnesium alloy group was close to that of bone tissue,and the density of the intramedullary nail in the stainless steel group was higher than that of bone tissue.At 8 weeks after surgery,the osteotomy lines of both groups were blurred,and the intramedullary nail in the magnesium alloy group had corroded and degraded.At 14 weeks after surgery,the osteotomy lines of both groups disappeared,and the intramedullary nail in the magnesium alloy group further corroded and degraded.(2)Micro-CT:At 2 weeks after surgery,callus began to form in both groups;8 weeks after surgery,the stainless steel group entered the callus remodeling stage,and a relatively dense bone structure was formed at the bone defect site,and the magnesium alloy group showed obvious callus hyperplasia at the bone defect site.At 14 weeks after surgery,the stainless steel group showed a mature bone remodeling process,and thick cortical bone was formed at the bone defect site,and thinner cortical bone was formed in the magnesium alloy group.(3)Hematoxylin-eosin staining:At 2 weeks after surgery,a large number of osteoblasts,osteocytes,a small number of osteoclasts and trabecular structures were observed in the magnesium alloy group,while relatively few osteoblasts and osteocytes were observed in the stainless steel group.At 8 weeks after surgery,a large number of osteoblasts,osteocytes,and mature trabecular structures were observed in the magnesium alloy group,while a large number of osteocytes and lamellar bones were observed in the stainless steel group.At 14 weeks after surgery,lamellar bones were observed in the magnesium alloy group,while mature bone tissue was observed in the stainless steel group.(4)Immunohistochemical staining and western blot assay:At the same time point,the expression levels of bone morphogenetic protein 2,osteocalcin,and RUNX2 proteins in the magnesium alloy group were higher than those in the stainless steel group.(5)The results showed that compared with stainless steel materials,Mg-Li-Gd alloy had no obvious advantage in promoting the formation of fracture healing structure.

Objective:To construct and validate a risk prediction model for major complications 30 days after surgery in the elderly patients with hip fracture.Methods:A retrospective study was conducted to analyze the clinical data of 276 elderly patients with hip fracture who had been admitted to Department of Trauma and Orthopaedics, The Hospital Affiliated to Chengde Medical University from June 2019 to December 2021. There were 96 males and 180 females with an age of (74.5±9.3) years, and 139 femoral neck fractures and 137 intertrochanteric fractures. The outcome of this study was whether major complications occurred within 30 days after surgery. Multiple logistic regression analysis identified the risk factors for major complications in the elderly patients with hip fracture within 30 days after surgery. The forward step-by-step method and likelihood ratio test were used to screen the best prediction model. A nomogram was constructed to display the model. The stability and effectiveness of the model were evaluated by the receiver operating characteristic curve (ROC), Hosmer-Lemeshow goodness-of-fit test, clinical decision curve and clinical impact curve analysis.Results:Logistic regression analysis showed that decreased preoperative hemoglobin ( P< 0.05), time from admission to surgery >72 hours ( OR=3.001, 95% CI: 1.564 to 5.758, P<0.001), control of nutritional status (CONUT) score >4 points ( OR=3.394, 95% CI: 1.724 to 6.680, P<0.001), and age-adjusted modified frailty index (aamFI) >2 points ( OR=2.875, 95% CI: 1.548 to 5.339, P= 0.001), increased operation time ( OR=1.016, 95% CI: 1.006 to 1.025, P=0.001), and surgical bleeding >60 mL ( OR=2.373, 95% CI: 1.016 to 5.540, P=0.046) were independent risk factors for major complications within 30 days after surgery in the elderly patients with hip fracture. The area under the ROC curve in the logistic risk prediction model was 0.846 (95% CI: 0.799 to 0.889), and the results of Hosmer-Lemeshow goodness-of-fit test showed ( χ2=8.080, P=0.426). The clinical decision curve and clinical impact curve showed that the prediction model was accurate and effective. Conclusion:Based on the patients' preoperative hemoglobin, time from admission to surgery, control of nutritional status score, age-adjusted modified frailty index, operation time and surgical blood loss, this study has constructed successfully a risk prediction model for complications 30 days after surgery in the elderly patients with hip fracture which enables medical staff to predict the occurrence of major postoperative complications.

Objective To evaluate the diagnostic value of radionuclide salivagram in children with pulmonary aspiration.Methods From March 2012 to June 2015,a total of 62 patients (37 males,25 females;age range:2 d-14 years) with suspected pediatric aspiration pneumonia were enrolled in this retrospective study.All patients underwent gastroesophageal reflux (GER) imaging and(or) radionuclide salivagram.Detection rate of pulmonary aspiration by the two imaging techniques was compared with x2 test.Results Of 62 patients,14 were diagnosed as pulmonary aspiration,including 1 detected by GER imaging,and 13 detected by salivagram.The detection rate for pulmonary aspiration by radionuclide salivagram (26.0％,13/50) was significantly higher than that by GER imaging (3.1％,1/32;x2=7.211,P＜0.05).Eight of the 13 cases with pulmonary aspiration diagnosed by radionuclide salivagram underwent upper gastrointestinal radiography,and 5 cases had visible contrast agent in the airway.Conclusion Radionuclide salivagram has a higher detection rate for pulmonary aspiration compared to GER imaging,and has good concordance with the traditional upper gastrointestinal radiography.