Abstrakt
The aim of the study was to determine the relationship between implant-associated complications and Dynamic Hip Screw (DHS) placement in the femoral neck, based on a Finite Element (FE) Analysis. Very diverse implant failures and subsequent complications can be encountered after introduction of the DHS.
We evaluated 308 dynamic hip screw osteosyntheses for pertrochanteric fractures in 297 patients. The ABAQUS 6.9 program was used for development of the FE model, and the analyses were performed in 5 modelled situations corresponding to five different screw locations.
Complications occurred in 10% of patients and re-operation was necessary in 3.9%. The highest risk of implant failure was associated with the screw situation in the upper third of the femoral neck.
Placing a dynamic hip screw in the middle third of the neck significantly reduced stresses in the plate and screw. The screw position in the upper third of the neck significantly increased these stresses.
The finite element analysis confirmed our clinical experience that the optimum position of the dynamic hip screw is in the middle third of the femoral neck.