Optimisation Of Fixation Methods For Vancouver Type B2 And B3 Periprosthetic Femoral Fracture Treatment

Periprosthetic femoral fractures (PFF) are a complication associated with total hip arthroplasty patients that can be both traumatic and challenging to treat. With the increasing age of the population and increasing prevalence of hip replacement surgery periprosthetic femoral fractures are expected to occur more frequently in the future. The most common type of PFF is the Vancouver Type B fracture that occurs near the tip of the original prosthesis. These fractures can be complicated further by loosening of the primary femoral stem (Type B2 fractures) and poor bone stock (Type B3 fractures). Clinical failures and unclear optimal treatment recommendations for many fractures suggest that further investigation is required.
This study mechanically tested experimental specimens representing the cemented long stem revision treatment of a Type B2 PFF at a range of loading orientations to evaluate their biomechanical response. From these specimens the axial stiffness, medial axial strain, distal lateral axial strain, and relative fracture movement were recorded under semi-physiological loading. These experimental results were also used to validate computational, finite element (FE), models of long stem PFF treatment. The computational models were shown to achieve reasonable agreement with the experimental data, such that they could be used to investigate a wider range of clinical scenarios. The FE models were then used to compare the relative effects of different cement mantle geometries, fracture location, fracture bridging distance, fracture angle, revision femoral stem length and osteoporosis.
The specific location and angle of the fracture appeared to have an effect on the bending response of the femur and the optimal treatment. Long stem revision treatment however seemed to be suitable for achieving stability around an unstable fracture and it may be possible to counter-act the increased risk of fixation failure in osteoporotic patients by selecting a longer bridging distance.