Background: Locked plating of displaced proximal humerus fractures is a reliable fixation method. Greater tuberosity (GT) failure is a known complication that may occur in the early post-operative period. Despite post...Background: Locked plating of displaced proximal humerus fractures is a reliable fixation method. Greater tuberosity (GT) failure is a known complication that may occur in the early post-operative period. Despite postoperative immobilization, the rotator cuff continues to exert significant forces on fracture fragments. Our hypothesis is that suture augmentation will provide greater stability of the GT than locked plating alone. To prove this we developed a three-part proximal humerus fracture model to test fracture fixation. Methods: A biomechanical study was performed on nine fresh frozen cadaveric humeri, simulating a three-part proximal humerus fracture (Neer Classification). Rotator cuff tendon insertions were preserved to physiologically load the proximal humerus. The fracture was reduced and fixed with a locked plate alone or a locked plate with suture augmentation of the GT to the rotator cuff tendons. Biomechanical testing utilized a materials testing machine and a three-dimensional motion capture system to quantify interfragmentary motion under torsional loading as a function of fixation type. Results: Greater torsional stability was observed in the suture-augmented group compared to the plate only group (p = 0.0012). There were two catastrophic failures in the plate only group while none of the suture reinforced constructs failed. Conclusions: In our model, suture-augmentation of the GT to the rotator cuff provided greater stability than locked plating alone. The current study provides a biome-chanical basis for reinforcing locked plate constructs with sutures. The added stability afforded by suture-augmentation may mitigate rotator cuff forces in the clinical setting, avoiding fracture displacement in the early postoperative rehabilitation period.展开更多
An optimal design method for two materials based on small amplitude homogenization is presented. The method allows to use quite general objective functions at the price that the two materials should have small contras...An optimal design method for two materials based on small amplitude homogenization is presented. The method allows to use quite general objective functions at the price that the two materials should have small contrasts in their relevant physical parameters. The following two applications are shown: Stress constrained compliance minimization and defect location in elastic bodies.展开更多
文摘Background: Locked plating of displaced proximal humerus fractures is a reliable fixation method. Greater tuberosity (GT) failure is a known complication that may occur in the early post-operative period. Despite postoperative immobilization, the rotator cuff continues to exert significant forces on fracture fragments. Our hypothesis is that suture augmentation will provide greater stability of the GT than locked plating alone. To prove this we developed a three-part proximal humerus fracture model to test fracture fixation. Methods: A biomechanical study was performed on nine fresh frozen cadaveric humeri, simulating a three-part proximal humerus fracture (Neer Classification). Rotator cuff tendon insertions were preserved to physiologically load the proximal humerus. The fracture was reduced and fixed with a locked plate alone or a locked plate with suture augmentation of the GT to the rotator cuff tendons. Biomechanical testing utilized a materials testing machine and a three-dimensional motion capture system to quantify interfragmentary motion under torsional loading as a function of fixation type. Results: Greater torsional stability was observed in the suture-augmented group compared to the plate only group (p = 0.0012). There were two catastrophic failures in the plate only group while none of the suture reinforced constructs failed. Conclusions: In our model, suture-augmentation of the GT to the rotator cuff provided greater stability than locked plating alone. The current study provides a biome-chanical basis for reinforcing locked plate constructs with sutures. The added stability afforded by suture-augmentation may mitigate rotator cuff forces in the clinical setting, avoiding fracture displacement in the early postoperative rehabilitation period.
基金supported by the project FONDECYT provided by the Chilean Commission for Scientific and Technological Research(No.1090334)
文摘An optimal design method for two materials based on small amplitude homogenization is presented. The method allows to use quite general objective functions at the price that the two materials should have small contrasts in their relevant physical parameters. The following two applications are shown: Stress constrained compliance minimization and defect location in elastic bodies.
