Abstract
Objectives: Treating hip intertrochanteric fracture (HIF) with dynamic hip screw (DHS) with two-hole side plate has gained satisfactory clinical results. Biomechanical tests also supported the use of DHS with two-hole side plate in treating HIF. However, complications with screws breakage have been reported; whether the events were related to the length of side plate remained unknown. The purpose of this study was to assess the stress distribution at dynamic hip screws with different length of side plate and movement of fracture fragments fixed by these implants. Methods: Finite element (FE) analysis was used to evaluate the reliability and durability of the implants. FE models of fractured proximal femur implanted with DHS with two, three and four-hole side plate and fractured healed model were built through CT scan images, and loads of single leg in stance and swing phase were applied to the FE models to evaluate the strength of HIF with DHS. Fatigue analysis of the three FE models was also performed. Results: DHS with four-hole side plate provided the best stability but also bore the greatest stress at its most distal screw. DHS with two-hole side plate exhibited the longest period of fatigue life cycle and shared more stress to the femur than the other two FE modes. Stress distribution showed that only the two distal screws of the side plate played major roles in holding the femur. Conclusion: In simple HIF fracture type, fragment of the fractured model fixed with DHS with two-hole side plate had the largest displacement, but not much different from that of three-hole side plate. Nevertheless, DHS with two-hole side plate revealed most life cycles and the lowest stress. Moreover, femoral shaft implanted with DHS with two-hole side plate sustained more even stress than those implanted with the other two implants.
Published Version
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