To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fracture... more To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fractures. In vitro biomechanical study. Bioengineering research laboratory. Thirty previously frozen human cadaveric tali were osteotomized across the talar neck. A wedge of bone 2 cm long and extending 50% of the medial to lateral and superior to inferior dimension of the talus was removed to create an unstable, comminuted fracture. The specimens were randomized to one of 3 fixation groups. The first group was fixed with 3 anterior-to-posterior screws. The second group was fixed with 2 cannulated screws inserted from posterior to anterior. The third group was fixed with 1 screw from anterior to posterior and a medially applied blade plate. Specimens were embedded in acrylic cement and mounted on an Instron mechanical testing machine. Loading was applied in the dorsal-medial direction to failure. For each specimen, the load-displacement curve, yield point, and 3 mm displacement point were recorded in response to controlled dorsal-medial loading to failure. Stiffness was calculated as the linear portion of the slope of the load (kN) versus displacement (mm) curve. Statistical analysis of the data was conducted using analysis of variance. The mean yield point of each of the fixation techniques tested exceeded 1.4 kN. No statistically significant difference was found between the fixation methods, even when variations in age and sex were considered. The mean yield point of the fixation techniques tested exceeds the theoretical stress across the talar neck during active motion. Anterior plate fixation provided equivalent stability to posterior screw fixation.
Background The purpose of this in-vitro study was to evaluate the effect of dynamic cyclic loadin... more Background The purpose of this in-vitro study was to evaluate the effect of dynamic cyclic loading on screw loosening of retightened abutment screw versus new abutment screw in both narrow and standard implants. Methods Separate acrylic resin blocks containing implant assembly (fixture, abutment, abutment screw, metal tube capping the abutment). Samples were divided into two main groups according to the diameter of implant: group 1 (GI 4.5-mm diameter) and group 2 (GII 3-mm diameter). Each group is subdivided into two subgroups according to the suggested option to manage screw loosening either by retightening (GIA, GIIA) or using new screws (GIB, GIIB). One hundred thousand cycles of eccentric dynamic cyclic loading (DCL) were applied before and after retightening or replacing the screw; then, removal torque loss (RTL) ratio was calculated, tabulated, and analyzed by t-student, ANOVA, pair wise Tukey’s tests. Results There were differences between GI and GII regarding the incidence ...
To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fracture... more To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fractures. In vitro biomechanical study. Bioengineering research laboratory. Thirty previously frozen human cadaveric tali were osteotomized across the talar neck. A wedge of bone 2 cm long and extending 50% of the medial to lateral and superior to inferior dimension of the talus was removed to create an unstable, comminuted fracture. The specimens were randomized to one of 3 fixation groups. The first group was fixed with 3 anterior-to-posterior screws. The second group was fixed with 2 cannulated screws inserted from posterior to anterior. The third group was fixed with 1 screw from anterior to posterior and a medially applied blade plate. Specimens were embedded in acrylic cement and mounted on an Instron mechanical testing machine. Loading was applied in the dorsal-medial direction to failure. For each specimen, the load-displacement curve, yield point, and 3 mm displacement point were recorded in response to controlled dorsal-medial loading to failure. Stiffness was calculated as the linear portion of the slope of the load (kN) versus displacement (mm) curve. Statistical analysis of the data was conducted using analysis of variance. The mean yield point of each of the fixation techniques tested exceeded 1.4 kN. No statistically significant difference was found between the fixation methods, even when variations in age and sex were considered. The mean yield point of the fixation techniques tested exceeds the theoretical stress across the talar neck during active motion. Anterior plate fixation provided equivalent stability to posterior screw fixation.
To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fracture... more To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fractures. In vitro biomechanical study. Bioengineering research laboratory. Thirty previously frozen human cadaveric tali were osteotomized across the talar neck. A wedge of bone 2 cm long and extending 50% of the medial to lateral and superior to inferior dimension of the talus was removed to create an unstable, comminuted fracture. The specimens were randomized to one of 3 fixation groups. The first group was fixed with 3 anterior-to-posterior screws. The second group was fixed with 2 cannulated screws inserted from posterior to anterior. The third group was fixed with 1 screw from anterior to posterior and a medially applied blade plate. Specimens were embedded in acrylic cement and mounted on an Instron mechanical testing machine. Loading was applied in the dorsal-medial direction to failure. For each specimen, the load-displacement curve, yield point, and 3 mm displacement point were recorded in response to controlled dorsal-medial loading to failure. Stiffness was calculated as the linear portion of the slope of the load (kN) versus displacement (mm) curve. Statistical analysis of the data was conducted using analysis of variance. The mean yield point of each of the fixation techniques tested exceeded 1.4 kN. No statistically significant difference was found between the fixation methods, even when variations in age and sex were considered. The mean yield point of the fixation techniques tested exceeds the theoretical stress across the talar neck during active motion. Anterior plate fixation provided equivalent stability to posterior screw fixation.
Background The purpose of this in-vitro study was to evaluate the effect of dynamic cyclic loadin... more Background The purpose of this in-vitro study was to evaluate the effect of dynamic cyclic loading on screw loosening of retightened abutment screw versus new abutment screw in both narrow and standard implants. Methods Separate acrylic resin blocks containing implant assembly (fixture, abutment, abutment screw, metal tube capping the abutment). Samples were divided into two main groups according to the diameter of implant: group 1 (GI 4.5-mm diameter) and group 2 (GII 3-mm diameter). Each group is subdivided into two subgroups according to the suggested option to manage screw loosening either by retightening (GIA, GIIA) or using new screws (GIB, GIIB). One hundred thousand cycles of eccentric dynamic cyclic loading (DCL) were applied before and after retightening or replacing the screw; then, removal torque loss (RTL) ratio was calculated, tabulated, and analyzed by t-student, ANOVA, pair wise Tukey’s tests. Results There were differences between GI and GII regarding the incidence ...
To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fracture... more To compare the mechanical performance of 3 fixation techniques for comminuted talar neck fractures. In vitro biomechanical study. Bioengineering research laboratory. Thirty previously frozen human cadaveric tali were osteotomized across the talar neck. A wedge of bone 2 cm long and extending 50% of the medial to lateral and superior to inferior dimension of the talus was removed to create an unstable, comminuted fracture. The specimens were randomized to one of 3 fixation groups. The first group was fixed with 3 anterior-to-posterior screws. The second group was fixed with 2 cannulated screws inserted from posterior to anterior. The third group was fixed with 1 screw from anterior to posterior and a medially applied blade plate. Specimens were embedded in acrylic cement and mounted on an Instron mechanical testing machine. Loading was applied in the dorsal-medial direction to failure. For each specimen, the load-displacement curve, yield point, and 3 mm displacement point were recorded in response to controlled dorsal-medial loading to failure. Stiffness was calculated as the linear portion of the slope of the load (kN) versus displacement (mm) curve. Statistical analysis of the data was conducted using analysis of variance. The mean yield point of each of the fixation techniques tested exceeded 1.4 kN. No statistically significant difference was found between the fixation methods, even when variations in age and sex were considered. The mean yield point of the fixation techniques tested exceeds the theoretical stress across the talar neck during active motion. Anterior plate fixation provided equivalent stability to posterior screw fixation.
Uploads