Influence of stem geometry on mechanics of cemented femoral hip components with a proximal bond.
Nonlinear, three-dimensional, finite element models of cemented femoral hip components with a proximal stem-cement bond were developed with use of a Charnley stem geometry and a modified Charnley stem geometry that had a cylindrical cross section over the distal two-thirds of the stem (Distal-Round). Peak tensile stresses in the proximal cement mantle increased 63 and 74% for the Charnley and Distal-Round stems, respectively, when the proximal stem-cement interface was debonded. The shear stresses over the stem-cement interface with a proximal bond were 29% larger for the Distal-Round stem than for the Charnley stem. After the proximal stem-cement interface was debonded, the peak tensile stresses in the cement mantle were 15% larger for the Distal-Round stem than for the Charnley stem. The results illustrate that stresses within the proximal cement mantle could be substantially reduced for both Charnley and Distal-Round stems through use of a proximal stem-cement bond. However, the risk of debonding may be higher for the Distal-Round stem because of increased shear stresses, and once debonded the risk of further loosening due to failure of the cement mantle would also be higher for the Distal-Round stem.
Mann
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KA
Department of Orthopedic Surgery, State University of New York-Health Science Center at Syracuse, USA. kmann@ansel.eng.uab.edu
Bartel
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Ayers
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D001843:Bone Cements; D003198:Computer Simulation; D005264:Femoral Fractures / Q000503:physiopathology; D005269:Femur / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D008962:Models, Theoretical; D016348:Osseointegration / Q000502:physiology; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D013718:Tensile Strength; D016474:Weight-Bearing / Q000502:physiology
D001843:Bone Cements