Finite element analysis of anterior ring injuries in unstable pelvic fractures treated by different methods / 中国骨伤

OBJECTIVE@#To compare the biomechanical stability of different fixation methods for anterior ring injury of unstable pelvic fractures, and to provide reference for clinical treatment.@*METHODS@#An unstable pelvic fracture model (Tile C) with one side of the sacroiliac joint dislocation and the pubic rami fracture was constructed via three-dimensional finite element analysis. Five different fixation methods were used in the front, and the rear was fixed with sacroiliac screws. The von Mises stress and strain distributions of different combinations of fixation methods were analyzed under mimicking standing conditions.@*RESULTS@#After being loaded with 500 N vertically, the maximum stress in the anterior fracture was 3.56 MPa in anterior pelvic external fixation (AEF) group, the total displacement and the vertical displacement of the Y axis at the sacroiliac joint and the fracture were not more than 1.5 mm. The maximum stress at fixation, the front of the fracture and sacroiliac joints in the anterior pelvic subcutaneous approach(APA) group and AEF, was significantly higher than anterior modified Stoppa approach(ASA) group, anterior pelvic Ilioinguinal approach (AIA) group, and canulated screw fixation(CSF) group. The total displacement and the vertical displacement of the Y axis at the sacroiliac joint and the fracture in APA group and AEF group were also greater than the other three groups.@*CONCLUSIONS@#Anterior ring injury of unstable pelvic fractures can be significantly improved after the fixation of the implants in the five combined methods. However, overall biomechanical properties of ASA, AIA and CSF group are superior to APA and AEF group.

Vacuum sealing drainage combined with discontinuous windowing technique for repairing large area exposed wound of Achilles tendon / 中国骨伤

<p><b>OBJECTIVE</b>To explore clinical effect of vacuum sealing drainage (VSD) combined with discontinuous windowing technique for repairing large area exposed wounds of Achilles tendon.</p><p><b>METHODS</b>From July 2009 to May 2014, 11 patients with large exposed wounds of Achilles tendon were treated, including 5 males and 6 females with an average age of 43 years old (aged from 7 to 65 years old). Among them, 4 cases were skin necrosis caused by heavy objects abrasion and contusion; 3 cases were caused by distal tibiofibula fractures; 3 cases were caused by bicycle-spoke injuries; 1 case was caused by diabetes. Areas of exposed Achilles tendon were from 6 cmx3 cm to 14 cmx5 cm without tendon rupture or bone exposed. After debridement, discontinuous fenestration on Achilles tendon was made by knife blade parallel with longitudinal axis of Achilles tendon, combined with Vacuum Sealing Drainage (VSD) treatment.</p><p><b>RESULTS</b>After drainage treatment with one VSD cycle (5 to 7 days), abundant fresh granulation tissues were growing on all wounds and survived well after the second phase dermatoplasty. All patients were followed up for 12 to 24 months, the color of skin flap was good, the texture was soft without burst. At 3 to 4 months after operation, subcutaneous fat was appeared under the flap, the skin was sliding, movement of ankle joints was good. No delayed Achilles tendon rupture were occurred.</p><p><b>CONCLUSION</b>Vacuum sealing drainage (VSD) combined with discontinuous fenestration is a simple, safe and effective method for repairing large area exposed wounds of Achilles tendon,which could minimize the secondary damage caused by wounds of skin flap grafting.</p>

Two-dimensional morphology of microleakage between dentin and adhesives / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe the two-dimensional morphology of microleakage between dentin and adhesives.</p><p><b>METHODS</b>The occlusal enamel of human third molar was cut out and the dentin exposed, followed by the application of dental adhesive (Prime & Bond NT, Contax and Adper Prompt), then a composite resin crown was built up. After storage in water (37 degrees C) for 24 h, all teeth were vertically serially sectioned into matchstick-shaped specimens through the bond interfaces. Half of the specimens from one tooth were subjected to thermal cycling and another half was stored in water (37 degrees C). All specimens were then immersed in ammoniacal silver nitrate solution, followed by developing solution. At last all specimens were subjected to microtensile test at a cross-head speed of 1.0 mm/min and their fractured surfaces were observed under scanning electron microscope.</p><p><b>RESULTS</b>The planar contour of all the silver leakage was various branching, treelike shape, spreading from the border of section to the center.</p><p><b>CONCLUSION</b>The planar contour of microleakage is treelike shape and its extent is influenced by adhesives and thermal cycling.</p>