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Introduction: A spiral clavicle plate has been accepted for its superior multidirectional compatibility in the treatment of midshaft clavicle fractures from a biomechanical perspective. However, the influence of the sextant angle (spiral level) definition on biomechanical performance has not been clarified. A conceptual finite element analysis was conducted to identify the advantages and drawbacks of spiral clavicle plates with various sextant angle definitions. Methods: Conventional superior and three different conceptual spiral plates with sextant angle definitions ranging from 45 to 135 degrees were constructed to restore an OTA 15-B1.3 midshaft clavicle fracture model. Three major loading scenarios (cantilever downward bending, axial compression, and axial torsion) were simulated to evaluate the reconstructed structural stiffness and the stress on the clavicle plate and bone screws. Results: The spiral clavicle plate demonstrated greater capability in resisting cantilever downward bending with an increase in sextant angle and showed comparable structural stiffness and implant stress compared to the superior clavicle plate. However, weakened resistance to axial compression load was noted for the spiral clavicle plate, with lowered stiffness and increased stress on the clavicle plate and screws as the spiral level increased. Conclusion: The spiral clavicle plate has been reported to offer multidirectional compatibility for the treatment of midshaft clavicle fractures, as well as geometric advantages in anatomical matching and reduced skin prominence after surgery. The current study supports that remarkable cantilever bending strength can be achieved with this plate. However, users must consider the potential drawback of lowered axial compression resistance in safety considerations. [ABSTRACT FROM AUTHOR]

Second-generation headless compression screws (HCSs) are commonly used for the fixation of small bones and articular fractures. However, there is a lack of biomechanical data regarding the application of such screws to radial head fractures. This study evaluated the mechanical properties of the fixation of radial head fractures using a single oblique HCS compared with those obtained using a standard locking radial head plate (LRHP) construct and a double cortical screw (DCS) construct. Radial synbone models were used for biomechanical tests of HCS, LRHP, and DCS constructs. All specimens were first cyclically loaded and then loaded to failure. The stiffness for the LRHP group was significantly higher than that for the other two groups, and that for the HCS group was significantly higher than that for the DCS group. The LRHP group had the greatest strength, followed by the HCS group and then the DCS group. The HCS construct demonstrated greater fixation strength than that of the commonly used cortical screws, although the plate group was the most stable. The present study revealed the feasibility of using a single oblique HCS, which has the advantages of being buried, requiring limited wound exposure, and having relatively easy operation, for treating simple radial head fractures., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)

Headless compression screws (HCSs) are commonly utilized devices for small bone fracture fixation. The Mini-Acutrak 2 and headless reduction (HLR) screws are the newer version types, in which both have fully threaded and variable pitch design. Specifically, the HLR is characterized by two thread runouts to facilitate implantation. With the thread runouts, the holding strength of the screw may be compromised. To the best of our knowledge, no study has examined the pullout force of the global sizes of a HCS. We sought to determine the pullout strength of the HLR and compare the strength of this screw with that of the Mini-Acutrak 2. Synthetic bone blocks with simulated transverse fractures were used to conduct the tests. Four commonly used sizes of the HLR were examined, and one Mini-Acutrak 2 was employed for comparison. Five screws of each size were tested. The pullout force of all screws that were tested in this study ranged from 45.23 to 233.22 N. The results revealed that the pullout force increased as the screw diameter increased. Interestingly, we found that one small screw outperformed the Mini-Acutrak 2, which has a larger diameter. This study provided extensive knowledge regarding the pullout strength of fully threaded HCSs of different sizes. An unexpected finding is that a small screw has higher holding power than a large one because of its increased number of threads. Therefore, we suggest that the thread number should be a critical consideration for the design of size distribution of HCSs.

Medial migration or cutout of the neck helical blade has commonly occurred in the treatment of trochanteric fracture of the femur. The position of the helical blade within the femoral head is one of the influencing factors that cause the blade to perforate the intact joint surface; however, the ideal placement of the helical blade is not currently known. A finite element model of a femur/nail construct was utilized to analyze five possible blade positions in the femoral head. Normal strain at the fracture surface, the minimum principal strain in the cancellous bone, and the von Mises stress in the implant itself were calculated and compared between different blade positions. The results showed that a large area of normal compressive strain at the fracture surface was observed in the inferior and posterior blade positions. The volume of cancellous bone strained to yielding in the femoral head and neck was lower for the inferior and posterior positions, whereas it was the highest for the superior position. The inferior and posterior positions had lower von Mises stress in the implant itself. The inferior and posterior positions may be the ideal position for the intramedullary nail with a helical neck blade.

Adequately shaped femoral plate is critical for the fixation of fracture in the pertrochanteric regions. Lateral aspect of greater trochanter is an important region where the proximal femoral plate anchored. However, little is known regarding the morphology of greater trochanter. The objective of this study was to measure main dimensions of greater trochanter and other regions in the proximal end of the femur to provide an anatomical basis for the design of the proximal femoral plate. Anthropometric data on the proximal femur were performed utilizing three-dimensional computational modeling. Computed tomography images of healthy femurs in 53 women and 47 men were contributed to three-dimensional femur modeling. All data were compared between male and female femora. The results showed that mean values for male group were found to be greater in most of measured femoral dimensions. Oppositely, females demonstrated higher neck-shaft angle on anteroposterior view and femoral anteversion angle. The anthropometric data can be used for the anatomical shape design of femoral plates for osteosynthesis of fractures in the trochanteric regions. A distinct plate design may be necessary to accommodate differences between the genders.