AUTHOR=Tinga Selena , Tuyn David D. , Kopp Rosalind J. , Kim Stanley E. 

TITLE=Biomechanical comparison of canine femurs implanted with either cemented (CFX®) or cementless (with lateral bolt) (BFX®+lb) total hip replacement under 4-point bending or torsional loads

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2023.999271

DOI=10.3389/fbioe.2023.999271

ISSN=2296-4185

ABSTRACT=<p><bold>Objective:</bold> Compare biomechanical properties of femurs implanted with either BioMedtrix<sup>™</sup> biological fixation with interlocking lateral bolt (BFX<sup>®</sup>+lb) or cemented (CFX<sup>®</sup>) stems when subjected to 4-point bending or axial torsional forces.</p><p><bold>Study Design:</bold> Twelve pairs of normal medium to large cadaveric canine femora were implanted with a BFX + lb (<italic>n</italic> = 12) and a CFX (<italic>n</italic> = 12) stem–one in the right and one in the left femora of the pair. Pre- and post-operative radiographs were made. Femora were tested to failure in either 4-point bending (<italic>n</italic> = 6 pairs) or axial torsion (<italic>n</italic> = 6 pairs), and stiffness, load or torque at failure, linear or angular displacement, and fracture configuration were noted.</p><p><bold>Results:</bold> Implant position was acceptable in all included femora, but CFX stems were placed in less anteversion than BFX + lb stems in the 4-point bending group (median (range) 5.8 (−1.9–16.3) vs. 15.9 (8.4–27.9) anteversion, respectively (<italic>p</italic> = 0.04)). CFX implanted femora were more stiff than BFX + lb implanted femora in axial torsion (median (range) 2,387 (1,659–3,068) vs. 1,192 (795–2,150) N*mm/<sup>o</sup>, respectively (<italic>p</italic> = 0.03)). One of each stem type, from different pairs, did not fail in axial torsion. There was no difference in stiffness or load to failure in 4-point bending, or in fracture configuration for either test, between implant groups.</p><p><bold>Conclusion:</bold> Increased stiffness of CFX implanted femurs under axial torsional forces may not be clinically relevant as both groups withstood expected <italic>in vivo</italic> forces. Based on this acute post-operative model using isolated forces, BFX + lb stems may be a suitable replacement for CFX stems in femurs with normal morphology (stovepipe and champagne flute morphology were not tested).</p>