In proximal humeral fracture except AO classification 11A1, fixations with a locking plate and nails are recommended. We performed mechanical tests to investigate whether retrograde intramedullary nailing has fixation...In proximal humeral fracture except AO classification 11A1, fixations with a locking plate and nails are recommended. We performed mechanical tests to investigate whether retrograde intramedullary nailing has fixation stability comparable to those of anterograde intramedullary nailing and locking plate which achieve clinically favorable outcomes. In retrograde intramedullary nailing, a nail entry point is made in the diaphysis, for which reduction of stiffness of the humerus is of concern. Thus, we investigated the influence of a nail entry point made in the diaphysis on humeral strength. Retrograde intramedullary nailing had fixation stability against bending and a force loaded in the rotation direction comparable to those of anterograde intramedullary nail and locking plate. Displacement by the main external force loaded on the humerus, compressive load, was less than half in the bone fixed by retrograde intramedullary nailing compared with that in the bone fixed with a locking plate, showing favorable fixation stability. It was clarified that stiffness of the humerus against rotation and a load in the compression direction is not reduced by a nail entry point made by retrograde intramedullary nailing.展开更多
Post cam mechanism of Posterior Stabilized (PS) knee prostheses is useful to realize intrinsic stability for cases with severe degeneration. However, some retrieval studies report severe failure of the polyethylene ti...Post cam mechanism of Posterior Stabilized (PS) knee prostheses is useful to realize intrinsic stability for cases with severe degeneration. However, some retrieval studies report severe failure of the polyethylene tibial post. We thought that severe failures were caused by high loads during daily activities. In the current study, we performed a compression test and a finite element analysis of the mechanical forces produced in the tibial post in posterior-stabilized knee prostheses in order to develop a specification for the tibial posts found in the polyethylene inserts of PS knee prostheses. Anterior tibial post impingement and posterior tibial post impingement were simulated. The surface pressure values detected in the compression test were consistent with those obtained in the FE analysis. Of the three designs, the lowest von Mises stress values were generated inside the round tibial post;therefore, tibial posts should be round. The risk of tibial post failure was low when 500 or 1000 N was loaded onto the knee joint. It was suggested that tibial post failure occurs when the shear strain at the base of the tibial post exceeds 0.1.展开更多
BACKGROUND Despite recent meta-analyses of randomized controlled trials(RCTs),there remains no consensus regarding the preferred surgical treatment for humeral shaft fractures.The fragility index(FI)is an emerging too...BACKGROUND Despite recent meta-analyses of randomized controlled trials(RCTs),there remains no consensus regarding the preferred surgical treatment for humeral shaft fractures.The fragility index(FI)is an emerging tool used to evaluate the robustness of RCTs by quantifying the number of participants in a study group that would need to switch outcomes in order to reverse the study conclusions.AIM To investigate the fragility index of randomized control trials assessing outcomes of operative fixation in proximal humerus fractures.METHODS We completed a systematic review of RCTs evaluating the surgical treatment of humeral shaft fractures.Inclusion criteria included:articles published in English;patients randomized and allotted in 1:1 ratio to 2 parallel arms;and dichotomous outcome variables.The FI was calculated for total complications,each complication individually,and secondary surgeries using the Fisher exact test,as previously published.RESULTS Fifteen RCTs were included in the analysis comparing open reduction plate osteosynthesis with dynamic compression plate or locking compression plate,intramedullary nail,and minimally invasive plate osteosynthesis.The median FI was 0 for all parameters analyzed.Regarding individual outcomes,the FI was 0 for 81/91(89%)of outcomes.The FI exceeded the number lost to follow up in only 2/91(2%)outcomes.CONCLUSION The FI shows that data from RCTs regarding operative treatment of humeral shaft fractures are fragile and does not demonstrate superiority of any particular surgical technique.展开更多
文摘In proximal humeral fracture except AO classification 11A1, fixations with a locking plate and nails are recommended. We performed mechanical tests to investigate whether retrograde intramedullary nailing has fixation stability comparable to those of anterograde intramedullary nailing and locking plate which achieve clinically favorable outcomes. In retrograde intramedullary nailing, a nail entry point is made in the diaphysis, for which reduction of stiffness of the humerus is of concern. Thus, we investigated the influence of a nail entry point made in the diaphysis on humeral strength. Retrograde intramedullary nailing had fixation stability against bending and a force loaded in the rotation direction comparable to those of anterograde intramedullary nail and locking plate. Displacement by the main external force loaded on the humerus, compressive load, was less than half in the bone fixed by retrograde intramedullary nailing compared with that in the bone fixed with a locking plate, showing favorable fixation stability. It was clarified that stiffness of the humerus against rotation and a load in the compression direction is not reduced by a nail entry point made by retrograde intramedullary nailing.
文摘Post cam mechanism of Posterior Stabilized (PS) knee prostheses is useful to realize intrinsic stability for cases with severe degeneration. However, some retrieval studies report severe failure of the polyethylene tibial post. We thought that severe failures were caused by high loads during daily activities. In the current study, we performed a compression test and a finite element analysis of the mechanical forces produced in the tibial post in posterior-stabilized knee prostheses in order to develop a specification for the tibial posts found in the polyethylene inserts of PS knee prostheses. Anterior tibial post impingement and posterior tibial post impingement were simulated. The surface pressure values detected in the compression test were consistent with those obtained in the FE analysis. Of the three designs, the lowest von Mises stress values were generated inside the round tibial post;therefore, tibial posts should be round. The risk of tibial post failure was low when 500 or 1000 N was loaded onto the knee joint. It was suggested that tibial post failure occurs when the shear strain at the base of the tibial post exceeds 0.1.
文摘BACKGROUND Despite recent meta-analyses of randomized controlled trials(RCTs),there remains no consensus regarding the preferred surgical treatment for humeral shaft fractures.The fragility index(FI)is an emerging tool used to evaluate the robustness of RCTs by quantifying the number of participants in a study group that would need to switch outcomes in order to reverse the study conclusions.AIM To investigate the fragility index of randomized control trials assessing outcomes of operative fixation in proximal humerus fractures.METHODS We completed a systematic review of RCTs evaluating the surgical treatment of humeral shaft fractures.Inclusion criteria included:articles published in English;patients randomized and allotted in 1:1 ratio to 2 parallel arms;and dichotomous outcome variables.The FI was calculated for total complications,each complication individually,and secondary surgeries using the Fisher exact test,as previously published.RESULTS Fifteen RCTs were included in the analysis comparing open reduction plate osteosynthesis with dynamic compression plate or locking compression plate,intramedullary nail,and minimally invasive plate osteosynthesis.The median FI was 0 for all parameters analyzed.Regarding individual outcomes,the FI was 0 for 81/91(89%)of outcomes.The FI exceeded the number lost to follow up in only 2/91(2%)outcomes.CONCLUSION The FI shows that data from RCTs regarding operative treatment of humeral shaft fractures are fragile and does not demonstrate superiority of any particular surgical technique.
