Strain shielding inspired re-design of proximal femoral stems for total hip arthroplasty.
A large number of hip prosthesis with different designs have been developed. However, the influence of hip implant design changes on the strains induced in the bone remains unclear. The purpose of this study is to better understand the mechanics of short stem total hip arthroplasty. Specifically, it investigates whether strain shielding can be avoided by changing implant shape and/or material properties. It is hypothesized that the re-design of existing implant designs can result in further reduction of strain shielding and thus keep bone loss minimal following total hip replacement. Finite element methods were used to compare healthy and implanted models. The local mechanics strains/stresses in the intact and implanted femurs were determined under patient-specific muscle and joint contact forces. Results suggest that small changes in implant geometry and material properties have no major effect on strain shielding. Furthermore, it was found that improvement depends on a dramatic re-design of the original implant design. Whereas the benefit of this strategy of modification of the original geometry of a given short-stemmed hip consists in reduced bone remodeling, care should be taken with regard to long-term bone anchorage and implant fatigue strength. It is also shown that geometrical and material changes have a limited potential in avoiding strain shielding even in short-stemmed implants. Finally, it is suggested that an understanding of the influence of these changes on the strain distribution within the bone can guide in the process of optimizing the current stem designs toward minimal strain shielding effects. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2534-2544, 2017.
Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Campus - Virchow Klinikum, Augustenburger Platz 1, Institutsgebäude Süd,13353 Berlin, Germany.|Centro Universitario de la Defensa, Academia General Militar, Ctra. Huesca s/n, 50090 Zaragoza, Spain.|Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain.
Myriam
0000-0002-8503-9291
M
Cilla
Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Campus - Virchow Klinikum, Augustenburger Platz 1, Institutsgebäude Süd,13353 Berlin, Germany.|Berlin-Brandenburg School for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany.|Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Sara
S
Checa
Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Campus - Virchow Klinikum, Augustenburger Platz 1, Institutsgebäude Süd,13353 Berlin, Germany.|Berlin-Brandenburg School for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany.|Berlin-Brandenburg Center for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Georg N
GN
Duda
D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D020342:Finite Element Analysis; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design
bone; computational modeling; hip and knee arthroplasty, finite element analysis; hip and knee arthroplasty, mechanics-kinematics; hip, hip and knee arthroplasty