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BACKGROUND: Ulnar osteotomy is firstly recommended for the therapy of Monteggia fracture in children. But,there is still a lack of biomechanical evidence to confirm its efficacy and safety. OBJECTIVE: To analyze the stress distribution on the humeroradial joint after ulnar osteotomy and to provide evidence for confirming the angular size and mechanism for ulnar osteotomy. METHODS: Nine elbow joints were subjected to different positions of physiological, posterior 15° and posterior 30° osteotomy, followed by loaded at different flexion angles in the neutral, pronation and supination positions, respectively, and then the detailed stress distribution and area in the humeroradial joint were obtained using I-Scan Stress Distribution Test system. One elbow joint was scanned by three-dimensional reconstruction CT and the three-dimensional finite element model was established by ANSYS software. The model was loaded with the same conditions based on the I-Scan Test RESULTS AND CONCLUSION: (1) I-Scan Test system showed that the stress concentration area was in the medial side of humeroradial joint when elbow joint extended after the posterior osteotomy. Following the buckling angle of elbows increased, the area of stress concentration was changed to posterior and stress and contact area of humeroradial joint decreased correspondingly. An increase of stress and decrease of contact area appeared after posterior osteotomy compared with physiological osteotomy. (2) According to the finite element analysis, after posterior 15° and 30° osteotomy, pressure of humeroradial joint concentrated in medial-posterior region and the stress was increased. (3) To conclude, ulnar posterior 30° osteotomy is superior to 15° in reducing the incidence of radial head redislocation of Monteggia fracture, but may induce osteoarthritis of humeroradial joint.
RESUMEN
Objective To determine the inhibitory effect and mechanism of metformin ( MF) on photo-damage of human skin fibroblasts ( HSF) induced by UVA .Methods Human skin fibroblasts were randomly divided into con-trol group, UVA group and UVA+MF group.The proliferation of HSF was detected by CCK-8 assay kit.SA-β-gal staining was performed to evaluate the senescence state .The level of ROS was examined by fluorescence probe DCF-DA staining using flow cytometry .Real-time PCR was used to determine mRNA expression of senescence -asso-ciated signals of MMP 1 and MMP3.The protein expression of MMP 1, MMP3, SOD1 and SOD2 were measured by Western blot .R esults To the proliferation of HSF , 0.01 mmol/L Metformin had no significant effect , but 0.1 and 1 mmol/L Metformin depressed significantly ( P<0.05 ) .Compared with the Control group , it showed that UVA irradiation increased the positive rate of SA-β-gal staining ( P<0.01 ) , the level of ROS ( P<0.05 ) , mRNA and protein expression of MMP1 and MMP3 significantly(P<0.01);Also decreased the expression of SOD1 and SOD2 ( P<0.01) .Compared with the UVA group , it showed that metformin decreased the positive rate of SA-β-gal staining (P<0.05), the level of ROS(P<0.05), mRNA and protein expression of MMP1 and MMP3 significantly(P<0.05);Also increased the expression of SOD 1 ( P<0.01 ) and SOD2.Conclusions Metfomin can inhibit photo-damage of human skin fibroblasts induced by UVA via decreasing ROS and metal matrix protease generation , also the improvement of cellular antioxidant capacity .