Osteoporotic proximal femur fractures are on the rise due to demographic change. The most dominant surgical treatment option for per/subtrochanteric fractures is cephalomedullary nailing. As it has ...been shown to increase primary stability, cement augmentation has become increasingly popular in the treatment of osteoporotic per/subtrochanteric femur fractures. The ultimate goal is to achieve stable osteosynthesis, allowing for rapid full weight-bearing to reduce possible postoperative complications. In recent years, bioresorbable bone cements have been developed and are now mainly used to fill bone voids. The aim of this study was to evaluate the biomechanical stability as well as the micro-structural behaviour of bioresorbable bone cements compared to conventional polymethylmethacrylate (PMMA)-cements in a subtrochanteric femur fracture model. Biomechanical as well as micro-computed tomography morphology analysis revealed no significant differences in both bone cements, as they showed equal mechanical stability and tight interdigitation into the spongious bone of the femoral head. Given the positive risk/benefit ratio for bioresorbable bone cements, their utilisation should be evaluated in future clinical studies, making them a promising alternative to PMMA-bone cements.
Purpose
Osteoporosis-related proximal femur fractures continue to increase significantly due to demographic change. This study was designed to evaluate the biomechanical stability of two different ...fixation methods (cerclage vs. screw) for refixation of a trochanter minor fragment in the pertrochanteric fractures in cadaveric bones.
Methods
Artificial bones (
n
= 14) and human bones (
n
= 16) were treated with a DHS and the trochanter minor fragment was reduced by cerclage wiring or direct screw fixation. After preloading the simulated iliopsoas with 10 N, a tensile test was performed, ending with either a 70% loss of strength or avulsion of the fragment. The mean values of the avulsion force and the surface strain were recorded.
Results
All tensile tests showed no significant differences between refixation using a direct screw or wire cerclage, for both artificial bones and human specimens. Absolute values showed higher avulsion forces after direct screw fixation than refixation with a wire cerclage. The surface tension of specimens treated with direct screw fixation was lower than that of specimens treated with wire cerclage. An opposite effect was seen in artificial bones. Both effects were not statistically significant.
Conclusion
Based on the equal stability after lag screw placement compared to cerclage wiring, we promote the placement of a lag screw into the lesser trochanter fragment in pertrochanteric femur fractures when using a dynamic hip screw.
Level of evidence
Level III.
Purpose Osteoporosis-related proximal femur fractures continue to increase significantly due to demographic change. This study was designed to evaluate the biomechanical stability of two different ...fixation methods (cerclage vs. screw) for refixation of a trochanter minor fragment in the pertrochanteric fractures in cadaveric bones. Methods Artificial bones (n = 14) and human bones (n = 16) were treated with a DHS and the trochanter minor fragment was reduced by cerclage wiring or direct screw fixation. After preloading the simulated iliopsoas with 10 N, a tensile test was performed, ending with either a 70% loss of strength or avulsion of the fragment. The mean values of the avulsion force and the surface strain were recorded. Results All tensile tests showed no significant differences between refixation using a direct screw or wire cerclage, for both artificial bones and human specimens. Absolute values showed higher avulsion forces after direct screw fixation than refixation with a wire cerclage. The surface tension of specimens treated with direct screw fixation was lower than that of specimens treated with wire cerclage. An opposite effect was seen in artificial bones. Both effects were not statistically significant. Conclusion Based on the equal stability after lag screw placement compared to cerclage wiring, we promote the placement of a lag screw into the lesser trochanter fragment in pertrochanteric femur fractures when using a dynamic hip screw.
Density functional theory computations at the B3LYP/SDDp//B3LYP/Lanl2DZ level were performed on model complexes derived from (Me(2)C(2)S(2))Mo(O)(2)-S-CuSMe(2-) or its oxo protonated form to gain ...insight into the reaction steps involved in substrate oxidation of a Mo-/Cu-dependent CO dehydrogenase. Only the bisoxo but not the hydroxo oxo complex was found to oxidize CO exothermically. A thiocarbamate complex structurally characterized as the reaction product of the enzyme with the inhibitor n-butylisonitrile corresponds to a thermodynamic well on the potential energy surface. For the formation of the analogous thiocarbonate complex from CO oxidation, however, we do not find a significant thermodynamic driving force. In the protein matrix of the enzyme this species should be further destabilized, as it requires the metal centers to move apart considerably from each other.
