بررسي اثر طول پيچ پلاك‌هاي قفل‌شونده وولار بر سفتي و پايداري اوليه در تثبيت شكستگي‌هاي ديستال زند زبرين

The impact of Distal Screw Length in Volar Plating on the Stiffness an‎d Initial Stability of Distal Radius Fractures

مهندسي پزشكي

Distal radius fractures are common wrist injuries. These fractures are often caused by falls an‎d can cause decreased function of the forearm an‎d wrist, ligament damage, an‎d pain. Fixing these fractures with a volar plate an‎d locking screws in the distal an‎d proximal areas increases stability an‎d accelerates the healing process. Distal screws in some cases pass bicortically through both layers of dense bone. This can be associated with the possibility of the screw protruding from the dorsal surface an‎d damaging the extensor tendons. These injuries are usually associated with pain, swelling, delayed healing, an‎d infection, leading to patient dissatisfaction. Therefore, shorter screws are recommended if they can provide the necessary stability in the fracture area. The aim of this study was to eva‎luate the effect of two screw lengths equal to 100% of the intercortical distance an‎d 75% of this distance in volar plating for distal extra-articular radius fractures, using the finite element method. In this study, two models of healthy an‎d osteoporotic bone were investigated. For this purpose, a 3D model of the radius was reconstructed based on CT scan images an‎d processed in MIMICS an‎d 3-MATIC software. In the next step, the fracture gap was created in 3-MATIC software. The locking screws were designed in SolidWorks software, an‎d then the screws were placed on the bone in the volar region along with the plate in 3-MATIC software. Then, loading conditions including axial compressive force, joint pressure, simulation of force applied from the wrist joints, dorsal an‎d volar bending forces were simulated in ABAQUS software. The initial stiffness an‎d stability of the fixed models were measured with a volar locking plate. The findings showed that as the screw length decreases, the contribution of force transmission to dense bone an‎d stabilizing segments increases. Also, fracture gap displacement increased when using shorter screws, which at first glance could lead to hesitation in using 75% screws. However, by examining the results of the paired t-test, it can be seen that in the eva‎luated samples in both healthy an‎d osteoporosis models, there is no significant difference between the two screw lengths in the loadings an‎d parameters eva‎luated. These results indicate that screws with a length of 75% can be used as a suitable alternative to screws with a length of 100% of the intercortical distance without significant reduction in stiffness an‎d mechanical stability, reducing the risk of tendon injury.

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