From healthy to osteoporotic: Exploring how bone quality alters implant performance in Pauwels type III fracture

Osteoporosis compromises bone strength, making bone more susceptible to fractures. Decreased bone density heightens susceptibility to femoral neck fractures. The study investigated the impact of bone density on implant performance across three categories of bone quality: healthy, osteopenic, and osteoporotic. The effectiveness of three commonly used implant types (Femoral Neck System, Dynamic Condylar Screw, and Dynamic Hip Screw, where later two equipped with an anti-rotational screw) was evaluated through finite element analysis for treating Pauwels type III fracture. The bone geometry and material properties were based on a subject-specific CT data. The density and Young's modulus of bone elements were adjusted to simulate osteopenic and osteoporotic bone. FE models were developed and the peak loading values for normal walking and stair climbing conditions were considered. Stability and performance of the implant were assessed using bone strain, implant stress, deformation and rotation of the femoral head, micromotion at the interfaces, strain shielding, and risk of implant cut-out. Except for DCS with AR-screw and FNS implants under stair climbing conditions in weaker bone qualities, the implant stress remained within the yield limit of Ti-alloy. The comprehensive assessment identified DHS2 as the preferred implant option for treating such fractures, even in poor bone quality. The risk of cut-out risk was up to 3.9% higher in DCS2 and 6.3% higher in FNS implanted models than in DHS2. The effect of change in bone quality was comparatively less in DHS2 implants than the other two types.