Background: AO type C3 distal radius fracture (DRF) is the most difficult-to-treat fracture type because of a tendency to shorten and collapse. The purpose of this study is to investigate the clinical and radiographic...Background: AO type C3 distal radius fracture (DRF) is the most difficult-to-treat fracture type because of a tendency to shorten and collapse. The purpose of this study is to investigate the clinical and radiographic outcomes of comminuted intra-articular DRFs treated with a dynamic external fixator combined with a volar locking plate (VLP). Methods: Eleven patients (mean age, 61 years) with comminuted intra-articular DRFs were treated with a dynamic type of external fixator combined with a VLP. Following reduction and fixation with a VLP, the dynamic external fixator was applied and the distal ball joint of the fixator was aligned with the lunate-capitate line. The ball joint was unlocked approximately 2 weeks after surgery to allow wrist mobilization. The fixator was removed 3 - 6 weeks (mean, 5 weeks) after surgery. Consequently, clinical and radiographic assessments were carried out at the final follow-up. Results: At the final follow-up, the mean range values of wrist extension and flexion were 76°and 64°, respectively. Compared with the contralateral side, the mean grip strength was 84%. The mean Modified Mayo Wrist Score and the Disabilities of the Arm, Shoulder and Hand score were 88 and 9, respectively. No significant differences in the radiographic parameters exist between after surgery and final follow-up. Conclusions: This study indicated that the dynamic wrist fixator combined with a VLP is effective for the treatment of AO type C3 DRFs.展开更多
Objective To evaluate effects of manipulative reduction,dynamic external fixator combined with limited internal fixation for the treatment of Pilon fractures.Methods From January 2007 to June 2009,manipulative reducti...Objective To evaluate effects of manipulative reduction,dynamic external fixator combined with limited internal fixation for the treatment of Pilon fractures.Methods From January 2007 to June 2009,manipulative reduction,dynamic external展开更多
One of the assumptions of previous research in evolutionary game dynamics is that individuals use only one rule to update their strategy. In reality, an individual's strategy update rules may change with the envir...One of the assumptions of previous research in evolutionary game dynamics is that individuals use only one rule to update their strategy. In reality, an individual's strategy update rules may change with the environment, and it is possible for an individual to use two or more rules to update their strategy. We consider the case where an individual updates strategies based on the Moran and imitation processes, and establish mixed stochastic evolutionary game dynamics by combining both processes. Our aim is to study how individuals change strategies based on two update rules and how this affects evolutionary game dynamics. We obtain an analytic expression and properties of the fixation probability and fixation times(the unconditional fixation time or conditional average fixation time) associated with our proposed process. We find unexpected results. The fixation probability within the proposed model is independent of the probabilities that the individual adopts the imitation rule update strategy. This implies that the fixation probability within the proposed model is equal to that from the Moran and imitation processes. The one-third rule holds in the proposed mixed model. However, under weak selection, the fixation times are different from those of the Moran and imitation processes because it is connected with the probability that individuals adopt an imitation update rule. Numerical examples are presented to illustrate the relationships between fixation times and the probability that an individual adopts the imitation update rule, as well as between fixation times and selection intensity. From the simulated analysis, we find that the fixation time for a mixed process is greater than that of the Moran process, but is less than that of the imitation process. Moreover, the fixation times for a cooperator in the proposed process increase as the probability of adopting an imitation update increases; however, the relationship becomes more complex than a linear relationship.展开更多
Background： We aimed to use the animal model of dynamic fixation to examine the interaction of the pedicle screw surface with sun＇ounding bone, and determine whether pedicle screws achieve good mechanical stability ...Background： We aimed to use the animal model of dynamic fixation to examine the interaction of the pedicle screw surface with sun＇ounding bone, and determine whether pedicle screws achieve good mechanical stability in the vertebrae. Methods： Twenty-four goats aged 2-3 years had Cosmic pedicle screws implanted into both sides of the L2-L5 pedicles. Twelve goats in the bilateral dynamic fixation group had fixation rods implanted in L2-L3 and L4-L5. Twelve goats in the unilateral dynamic fixation group had fixation rods randomly fixed on one side of the lumbar spine. The side that was not implanted with fixation rods was used as a static control group. Results： In the static control group, new bone was formed around the pedicle screw and on the screw surthce. In the unilateral and bilateral dynamic fixation groups, large amounts of connective tissue formed between and around the screw threads, with no new bone formation on the screw surlhce; the pedicle screws were loose after the fixed rods were removed. The bone mineral density and morphological parameters of the region of interest （ROI） in the unilateral and bilateral dynamic fixation group were not significantly different （P 〉 0.05）, but were lower in the fixed groups than the static control group （P 〈 0.05）. This showed the description bone of the ROI in the static control group was greater than in the fixation groups. Under loading conditions, the pedicle screw maximum pull force was not significantly different between the bilateral and unilateral dynamic fixation groups （P 〉 0.05）： however the maximum pull force of the fixation groups was significantly less than the static control group （P 〈 0.01 ）. Conclusions： Fibrous connective tissue formed at the bone-screw interface tinder unilateral and bilateral pedicle dynamic fixation, and the pedicle screws lost mechanical stability in the vertebrae.展开更多
文摘Background: AO type C3 distal radius fracture (DRF) is the most difficult-to-treat fracture type because of a tendency to shorten and collapse. The purpose of this study is to investigate the clinical and radiographic outcomes of comminuted intra-articular DRFs treated with a dynamic external fixator combined with a volar locking plate (VLP). Methods: Eleven patients (mean age, 61 years) with comminuted intra-articular DRFs were treated with a dynamic type of external fixator combined with a VLP. Following reduction and fixation with a VLP, the dynamic external fixator was applied and the distal ball joint of the fixator was aligned with the lunate-capitate line. The ball joint was unlocked approximately 2 weeks after surgery to allow wrist mobilization. The fixator was removed 3 - 6 weeks (mean, 5 weeks) after surgery. Consequently, clinical and radiographic assessments were carried out at the final follow-up. Results: At the final follow-up, the mean range values of wrist extension and flexion were 76°and 64°, respectively. Compared with the contralateral side, the mean grip strength was 84%. The mean Modified Mayo Wrist Score and the Disabilities of the Arm, Shoulder and Hand score were 88 and 9, respectively. No significant differences in the radiographic parameters exist between after surgery and final follow-up. Conclusions: This study indicated that the dynamic wrist fixator combined with a VLP is effective for the treatment of AO type C3 DRFs.
文摘Objective To evaluate effects of manipulative reduction,dynamic external fixator combined with limited internal fixation for the treatment of Pilon fractures.Methods From January 2007 to June 2009,manipulative reduction,dynamic external
基金Project supported by the National Natural Science Foundation of China(Grant Nos.71871171,71871173,and 71832010)
文摘One of the assumptions of previous research in evolutionary game dynamics is that individuals use only one rule to update their strategy. In reality, an individual's strategy update rules may change with the environment, and it is possible for an individual to use two or more rules to update their strategy. We consider the case where an individual updates strategies based on the Moran and imitation processes, and establish mixed stochastic evolutionary game dynamics by combining both processes. Our aim is to study how individuals change strategies based on two update rules and how this affects evolutionary game dynamics. We obtain an analytic expression and properties of the fixation probability and fixation times(the unconditional fixation time or conditional average fixation time) associated with our proposed process. We find unexpected results. The fixation probability within the proposed model is independent of the probabilities that the individual adopts the imitation rule update strategy. This implies that the fixation probability within the proposed model is equal to that from the Moran and imitation processes. The one-third rule holds in the proposed mixed model. However, under weak selection, the fixation times are different from those of the Moran and imitation processes because it is connected with the probability that individuals adopt an imitation update rule. Numerical examples are presented to illustrate the relationships between fixation times and the probability that an individual adopts the imitation update rule, as well as between fixation times and selection intensity. From the simulated analysis, we find that the fixation time for a mixed process is greater than that of the Moran process, but is less than that of the imitation process. Moreover, the fixation times for a cooperator in the proposed process increase as the probability of adopting an imitation update increases; however, the relationship becomes more complex than a linear relationship.
文摘Background： We aimed to use the animal model of dynamic fixation to examine the interaction of the pedicle screw surface with sun＇ounding bone, and determine whether pedicle screws achieve good mechanical stability in the vertebrae. Methods： Twenty-four goats aged 2-3 years had Cosmic pedicle screws implanted into both sides of the L2-L5 pedicles. Twelve goats in the bilateral dynamic fixation group had fixation rods implanted in L2-L3 and L4-L5. Twelve goats in the unilateral dynamic fixation group had fixation rods randomly fixed on one side of the lumbar spine. The side that was not implanted with fixation rods was used as a static control group. Results： In the static control group, new bone was formed around the pedicle screw and on the screw surthce. In the unilateral and bilateral dynamic fixation groups, large amounts of connective tissue formed between and around the screw threads, with no new bone formation on the screw surlhce; the pedicle screws were loose after the fixed rods were removed. The bone mineral density and morphological parameters of the region of interest （ROI） in the unilateral and bilateral dynamic fixation group were not significantly different （P 〉 0.05）, but were lower in the fixed groups than the static control group （P 〈 0.05）. This showed the description bone of the ROI in the static control group was greater than in the fixation groups. Under loading conditions, the pedicle screw maximum pull force was not significantly different between the bilateral and unilateral dynamic fixation groups （P 〉 0.05）： however the maximum pull force of the fixation groups was significantly less than the static control group （P 〈 0.01 ）. Conclusions： Fibrous connective tissue formed at the bone-screw interface tinder unilateral and bilateral pedicle dynamic fixation, and the pedicle screws lost mechanical stability in the vertebrae.
