A plasma-sprayed titanium proximal coating reduces the risk of periprosthetic femoral fracture in cementless hip arthroplasty

BACKGROUND: The design of femoral component used in total hip arthroplasty is known to influence the incidence of periprosthetic femoral fractures (PFFs) in cementless hip arthroplasty. OBJECTIVE: This study was undertaken to determine if 2 potential changes to an existing ABG II-standard cementless implant - addition of a roughened titanium plasma-sprayed proximal coating (ABG II-plasma) and lack of medial scales (ABG II-NMS) could decrease the risk of PFF in the intraoperative and early postoperative periods. METHODS: Six pairs of human cadaveric femurs were harvested and divided into 2 groups, each receiving either of the altered implants and ABG II-standard (control). Each implant was tested in a biomechanical setup in a single-legged stance orientation. Surface strains were measured in intact femurs, during implant insertion, cyclic loading of the bone with the implant, and loading to failure. Strains with the ABG II-standard and the altered implants were compared. FINDINGS: ABG II-plasma showed better load-bearing capacity, with an average 42% greater failure load than that of ABG II-standard. The cortical hoop, axial and mean strains ABG II-plasma were less than those of ABG II-standard, demonstrating decreased tensile behaviour and better load transfer to the proximal femur. The final residual hoop strains in ABG II-plasma were closer to those of intact bone as compared to the standard stem. No differences in strains were observed between the standard stem and ABG II-NMS. CONCLUSION: The increased load-bearing capacity and decreased proximal surface strains on femurs implanted with ABG II-plasma stem should reduce the risks of intraoperative and early postoperative PFF.