چكيده لاتين
Fracture of the humerus shaft is one of the most common injuries of the upper limb, usually caused by accidents, severe trauma, or sports activities. One of the common and effective methods in treating these types of fractures is the use of bone fixation plates. In recent years, magnesium-based alloys have been considered as a promising option for the manufacture of temporary orthopedic implants due to their good mechanical properties, high biocompatibility, and biodegradability. Magnesium alloy WE43, due to its good strength, low weight, favorable biological behavior, and controllable degradation rate, can be a suitable alternative to permanent metal implants such as stainless steel and titanium alloys, and reduce the need for secondary surgery for implant removal. In this study, a biodegradable bone fixation plate made of WE43 magnesium alloy was designed, modeled, and analyzed for the treatment of diaphyseal fractures of the humerus. The geometric design of the plate was appropriate for the anatomy of the humerus and included six holes for installing six fixation screws. Geometric modeling was performed using SolidWorks software. Then, mechanical analyses were performed using Abaqus software under physiological loading conditions. In this regard, three types of loading were applied to the model, including an axial force of 500 Newtons, a torsional torque of 15 Newton meters, and a bending load of 25 Newtons. In order to simulate the biodegradable behavior of WE43 alloy in the body environment, a uniform degradation rate of 0.5 mm/year was considered and the geometric changes of the plate were investigated over a six-month period at time intervals including month 0, month 1.5, month 3, month 4.5 and month 6. During this time interval, a gradual decrease in the length, width and thickness of the plate was considered and stress analyses were performed for each stage. The results of the analyses showed that the maximum stresses generated at all time stages were lower than the yield stress limits of the humerus (100 to 140 MPa) and also lower than the yield stress of the WE43 magnesium alloy (210 MPa). Based on the results obtained, the WE43 alloy fixation plate, while maintaining mechanical stability during the bone healing process, exhibits controlled destructive behavior and meets the clinical requirements for the treatment of humeral shaft fractures in terms of strength and safety. This research can be considered an effective step towards the development of biodegradable implants, reducing dependence on permanent metal implants, and promoting new technologies
