Premium
Biomechanical Evaluation of Screw‐In Femoral Implant in Cementless Total Hip System
Author(s) -
Kim James Y.,
Hayashi Kei,
Garcia Tanya C.,
Kim SunYoung,
Entwistle Rachel,
Kapatkin Amy S.,
Stover Susan M.
Publication year - 2012
Publication title -
veterinary surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 79
eISSN - 1532-950X
pISSN - 0161-3499
DOI - 10.1111/j.1532-950x.2011.00890.x
Subject(s) - cadaveric spasm , femoral head , femur , medicine , prosthesis , anatomy , biomechanics , implant , biomedical engineering , surgery
Objective To compare (1) proximal femoral axial strains, (2) femoral head deflection, and (3) failure mechanical properties, between H elica head and neck prosthesis implanted femora and normal femora. Study Design In vitro study. Sample Population Cadaveric canine femora (n = 5 pair). Methods Femoral bone strains and head displacement during in vitro simulation of midstance of the gallop were evaluated using cadaveric femurs cyclically loaded in vitro. Strains and displacements were compared within femurs, before and after, prosthesis implantation; and throughout cycling to seek evidence of movement with cyclic loading. Subsequently, implanted femurs and contralateral, intact femurs were loaded to failure to compare failure mechanical properties and modes of failure. Results Proximal femoral axial strains were significantly different between intact and implanted femora on all 4 cortical surfaces ( P < .05). Compressive strains were lower in the implanted femur on all cortical surfaces, except on the caudal surface which was higher. No difference was noted for femoral head angle under an axial load corresponding to gallop ( P > .05). Vertical head displacement was ∼0.1 mm greater for implanted femora than intact femora ( P < .05). Yield and failure loads and yield energy of implanted femora were 39–54% lower than those for intact femora ( P < .05). Mode of failure for both the intact and implanted femora did not appear to be different. Conclusion H elica femoral prosthesis alters strain distribution in the proximal aspect of the femur and exhibits initial micromotion. Failure load in axial compression of the H elica‐implanted femur is less than that of the normal femur, but greater than that expected in vivo.