Affiliations: [a] Biomedical Engineering, AMME, University of Sydney, Sydney, NSW, Australia | [b] Specialist Orthopedic Group, Sydney, NSW, Australia | [c] The Australian School of Advanced Medicine, Macquarie University, Sydney, NSW, Australia | [d] Medical Device Research Australia, Sydney, NSW, Australia | [e] Murray Maxwell Biomechanics Laboratory, Kolling Institute, Sydney University, Sydney, NSW, Australia | [f] WorelyParsons Advanced Analysis, Sydney, NSW, Australia
Correspondence:
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Address for correspondence: Elizabeth Kolos, Biomedical Engineering, AMME J07, University of Sydney, Sydney, NSW 2006, Australia. Tel.: +61 411097173; E-mail: [email protected].
Abstract: 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.
