Elastic stable intramedullary nailing (ESIN) is a well-accepted fixation method of long bone fractures in children.The advantages of ESIN include primary bone union with avoidance of growth plate injury and minimum invasive surgery.The good results of ESIN are obtained when surgeons have a good knowledge of the principle of the correction of the fracture and its stability, especially in the understanding of the unique pathophysiology characteristics of pediatric fractures.This review discussed the biomechanical mechanisms of ESIN, and the principles,indications and contraindications of ESIN in the treatment of pediatric long bone fractures.The article also comprehensively introduced the application of ESIN in femur,tibia,fibula,humerus, ulna, radius,clavicle and metacarpal bone fractures.The technique details of nailing, preoperative planning, positioning of the patient, sizing of the nail, entry points for the nail, reduction maneuvers for safe passage of nails through the fracture site, and postoperative management were also introduced in this review.

[Objective]To study the effects of verapamil on the immediate-early gene(IEGs)expression of bone marrow mesenchymal stimulated by mechanical strain,and deduce the effects of calcium ion channel on the early responses of children bone marrow mesenchymal stem cells(MSCs)to mechanical strain in vitro.[Method]MSCs were isolated and cultured.The 3-6th generational MSCs were stimulated in different time by mechanical and(or)verapamil(20?mol/l).Flow cytometry was applied to measure intracellular free Ca2+ at once.Early-response genes /proteins(c-fos,c-jun and c-myc)were examined by RT-PCR and immunocytochemical stain.[Result]The application of mechanical strain increased intracellular c-fos,c-jun and c-myc mRNA /protein levels.The resulting effect is partially inhibited before MSCs were preincubated with verapamil(P

BACKGROUND: It has been reported that in China, human bone marrow mesenchymal stem ceils are mostly harvested from adults. Studies on bone marrow mesenchymal stem cells in children are few.OBJECTIVE: To isolate and expand bone marrow mesenchymal stem cells from children, and to analyze the biological characteristics of bone marrow mesenchymal stem cells and their potential of differentiating into osteoblasts, adipocytes and neural like cells.DESIGN: Observational comparative study.SETTING: Tongji Medical College, Huazhong University of Science and Technology.MATERIALS: Experiments were performed at the Laboratory of Department of Orthopaedics of Wuhan Tongji Hospital from March to September 2006. Bone marrow mesenchymal stem cells were collected from one boy patient and two girl patients aged 5-8 years, who received pelvis osteotomy for dysplasia of the hip joint. The experimental procedures were approved by the Hospital Ethics Committee and family members of all children patients singed the informed consent.Dexamethasone, vitamin C, β-sodium glycerophosphate, 3-1sobutyl-1-methylxanthine, insulin, indometacin and butylated hydroxyanisole were bought from Sigma Company. Dimethyl sulphoxide was purchased from Amersco Company.METHODS: Bone marrow mesenchymal stem cells were cultured from mononuclear cells isolated over a Percoll gradient.Bone marrow mesenchymal stem cells were observed under an inverted phase contrast microscope. Bone marrow mesenchymal stem cells could differentiate into osteoblasts, adipocytes and neural like cells with osteoblast inductor (β-sodium glycerophosphate, dexamethasone, vitamin C), lipoblast inductor (dexamethasone, 3-isobutyl-1-methylxanthine,bovine insulin, indometacin) and serum-free medium inductor (dimethyl sulphoxide, butylated hydroxyanisole) respectively.Osteoblast marker (alkaline phosphatase, osteocalcin mRNA, calcium node), adipocyte marker (lipid droplet, PPAR γ-2mRNA) and neural ceil-like marker (nissl body, neuron specific enolase, neurofilament protein) were respectively determined by the immunohistochemical method, polymerase chain reaction and immunocytochemical method.MAIN OUTCOME MEASURES: ①Appearance and proliferation of bone marrow mesenchymal stem ceils from children,and ②determination results of osteoblast, adipocyte and neural cell markers.RESULTS: ①Children bone marrow mesenchymal stem cells could easily adhere to the wall, appeared fusiform, had high reproductive activity and arranged vortically after fusing. ②Appearance of bone marrow mesenchymal stem cells changed after receiving inductor. Osteoblast marker, adipocyte marker and neural cell-like marker were positive after chemical staining, polumerase chain reaction and immunocyte staining.CONCLUSION: Children bone marrow mesenchymai stem cells show stable proliferation, passage and multi-direction differentiation towards osteoblasts, adipocytes and neural like cells.

Die Prim?rstabilit?t von Pedikelschrauben im Knochen h?ngt in hohem Masse von der Knochendichte ab. Die Augmentation mit Zement ist ein klinisch einsetzbares Verfahren, um die Schrauben-Verankerung im osteoporotischen Knochen zu verbessern.In dieser Studie wurde eine neuartiges resorbierbares Knochenersatzmaterial (α-BSMTM) für diese Augmentation benutzt. Biomechanische Testungen wurden in vitro bei 16 Lendwirbelkorpern (L3-L5) aus 6 Individuen(75,2±13,7 Jahre) durchgeführt. Vor der biomechanischen Testung wurde bei allen Pr?paraten die trabekul?re Knochendichte mittels pQCT gemessen und beide Pedikel mit USS-Pedikelschrauben (5,0 mm × 45 mm) besetzt, von welchen eine mit α-BSMTM augmentiert war. Beim axialen Auszugstest wurden die maximale axiale Auszugskraft (F-max) sowie die Energieaufnahme bestimmt. Der Medianwert der F-max stieg beim Auszugstest durch die Zementierung mit α-BSMTM um 80 % von 370 N (ohne Zement) auf 665 N (mit Zement). Die Energieaufnahme bis zum Erreichen der F-max (E-F-max) und bei Dislokation bis 2,0 mm (E-2 mm) steigerte sich ebenfalls um 83 % und 68 %. Die Unterschiede waren signifikant. (Wilcoxon′s-Test, P<0,01) Die Ausreisskrafte F-max (ohne oder mit Zement) korrelierten eng mit der Knochendichte (r=0,9056 und r=0,9585). Unsere Resultate zeigen, da eine Augmentation mit dem α-BSMTM die prim?re Stabilit?t von Pedikelschrauben verbessern kann. Der Effekt scheint auf einer Optimierung der Kontaktfl?che und einer Aussteifung der schraubennahen Spongiosa zu beruhen. Das Material konnte geeignet sein, die Verankerung von Pedikelschrauben bei osteoporotischen Patieten zu verbessern.

Die Prim?rstabilit?t von Pedikelschrauben im Knochen h?ngt in hohem Masse von der Knochendichte ab. Die Augmentation mit Zement ist ein klinisch einsetzbares Verfahren, um die Schrauben-Verankerung im osteoporotischen Knochen zu verbessern.In dieser Studie wurde eine neuartiges resorbierbares Knochenersatzmaterial (α-BSMTM) für diese Augmentation benutzt. Biomechanische Testungen wurden in vitro bei 16 Lendwirbelkorpern (L3-L5) aus 6 Individuen(75,2±13,7 Jahre) durchgeführt. Vor der biomechanischen Testung wurde bei allen Pr?paraten die trabekul?re Knochendichte mittels pQCT gemessen und beide Pedikel mit USS-Pedikelschrauben (5,0 mm × 45 mm) besetzt, von welchen eine mit α-BSMTM augmentiert war. Beim axialen Auszugstest wurden die maximale axiale Auszugskraft (F-max) sowie die Energieaufnahme bestimmt. Der Medianwert der F-max stieg beim Auszugstest durch die Zementierung mit α-BSMTM um 80 % von 370 N (ohne Zement) auf 665 N (mit Zement). Die Energieaufnahme bis zum Erreichen der F-max (E-F-max) und bei Dislokation bis 2,0 mm (E-2 mm) steigerte sich ebenfalls um 83 % und 68 %. Die Unterschiede waren signifikant. (Wilcoxon′s-Test, P<0,01) Die Ausreisskrafte F-max (ohne oder mit Zement) korrelierten eng mit der Knochendichte (r=0,9056 und r=0,9585). Unsere Resultate zeigen, da eine Augmentation mit dem α-BSMTM die prim?re Stabilit?t von Pedikelschrauben verbessern kann. Der Effekt scheint auf einer Optimierung der Kontaktfl?che und einer Aussteifung der schraubennahen Spongiosa zu beruhen. Das Material konnte geeignet sein, die Verankerung von Pedikelschrauben bei osteoporotischen Patieten zu verbessern.

Objective:To identify the risk factors for premature proximal femur physeal closure (PPC) in children treated surgically for femoral neck fractures.Methods:Data of 106 children with an open triradiate cartilage who were treated surgically for a femoral neck fracture were retrospectively analyzed. Age, gender, laterality, mechanism of injury, the type of fracture, initial displacement, time to reduction, fixation method, whether the implant crossed the physeal plate, reduction method, reduction quality and development of femoral head avascular necrosis (AVN) were collected. PPC of the proximal femur was assessed through postoperative 6-12 months radiographs.Results:A total of 106 patients with an open triradiate cartilage were followed up, with an average duration of 20.4±13.3 months (range, 6-86 months). The overall rate of PPC following paediatric femoral neck fractures treated surgically was 36.8% (39/106). Among the 39 patients with PPC, 25 were males and 14 were females; the average age at the time of injury was 9.7±3.6 years (range, 3-15 years); 23 patients were involved in left hips and 16 were in right; the mechanisms of injury included motor vehicle accident in 5 fractures, falling injury in 21, sports-related injury in 12 and other causes in 1 fracture; two hips were Delbet type I, and 26 hips and 11 hips were Delbet type II and III, separately; type II and III of initial displacement were involved in 26 and 13 patients, separately; the mean duration from injury to surgery was 3.3±2.8 d (range, 1-14 d); 2 hips were treated with Kirschner wires, 35 hips with screw fixation, and the remaining 2 hips underwent screw and plate fixation; 2 hips had the hardware crossing the proximal femoral growth plate, and the remaining 37 hips didn’t; 15 hips were treated by closed reduction and internal fixation, and the other 24 hips underwent open reduction and internal fixation; anatomical reduction was achieved in 14 patients, acceptable reduction in 24 hips and unacceptable reduction in 1 hip; 24 hips developed AVN at the latest follow-up and the remaining 15 hips didn’t. Statistical analysis indicated that age ( t=3.875, P< 0.001), the severity of initial displacement ( Z=-2.118, P=0.034) and the rate of AVN ( χ2=42.280, P< 0.001) in patients with PPC were significantly higher than those in patients without; Logistic regression analysis confirmed age ( OR=1.288, P=0.011) and AVN ( OR=40.336, P< 0.001) as risk factors for PPC. ROC curve analysis indicated 10 years was the cut off age to significantly increase the rate of PPC. The rate of PPC in patients aged over 10 years (63.6%, 21/33) was significantly higher than that (24.7%, 18/73) in those aged less than 10 years ( χ2=14.848, P< 0.001). Conclusion:Age over 10 years and AVN are risk factors for PPC in children with femoral neck fractures treated surgically.