Metaphyseal anchoring short stem hip arthroplasty provides a more physiological load transfer: a comparative finite element analysis study

• Published in: Journal of orthopaedic surgery and research Vol. 15; no. 1; pp. 1 - 10
• Main Authors: Yan, Shuang G., Chevalier, Yan, Liu, Fanxiao, Hua, Xingyi, Schreiner, Anna, Jansson, Volkmar, Schmidutz, Florian
• Format: Journal Article
• Language: English
• Published: London BioMed Central Ltd 29.10.2020; BioMed Central; BMC
• Subjects: Biomechanics; Bones; CAT scans; Comparative analysis; Computed tomography; Design; Femur; Finite element analysis; Finite element method; Hip; Hip replacement arthroplasty; Joint replacement surgery; Joint surgery; Laboratories; Mathematical models; Mechanical loading; Medical imaging; Orthopedics; Physiological aspects; Physiology; Prostheses; SHA; Stem; Stress shielding; Total hip arthroplasty; Transplants & implants; Unloading; United States > US; Germany
• ISSN: 1749-799X; 1749-799X
• DOI: 10.1186/s13018-020-02027-4

Background Short stem total hip arthroplasty (SHA) preserves femoral bone stock and is supposed to provide a more natural load transfer compared to standard stem total hip arthroplasty (THA). As comparative biomechanical reference data are rare we used a finite element analysis (FEA) approach to compare cortical load transfer after implantations of a metaphyseal anchoring short and standard stem in native biomechanical femora. Methods The subject specific finite element models of biomechanical femora, one native and two with implanted metaphyseal anchoring SHA (Metha, B. Braun Aesculap) and standard THA (CLS, Zimmer-Biomet), were generated from computed tomography datasets. The loading configuration was performed with an axial force of 1400 N. Von Mises stress was used to investigate the change of cortical stress distribution. Results Compared to the native femur, a considerable reduction of cortical stress was recorded after implantation of SHA and standard THA. The SHA showed less reduction proximally with a significant higher metaphyseal cortical stress compared to standard THA. Moreover, the highest peak stresses were observed metaphyseal for the SHA stem while for the standard THA high stress pattern was observed more distally. Conclusions Both, short and standard THA, cause unloading of the proximal femur. However, the metaphyseal anchoring SHA features a clearly favorable pattern in terms of a lower reduction proximally and improved metaphyseal loading, while standard THA shows a higher proximal unloading and more distal load transfer. These load patterns implicate a reduced stress shielding proximally for metaphyseal anchoring SHA stems and might be able to translate in a better bone preservation. Keywords: Stress shielding, Finite element analysis, Total hip arthroplasty, SHA, Stem