Similitude of cement‐bone micromechanics in cemented rat and human knee replacement

A preclinical rat knee replacement model was recently developed to explore the biological and mechanobiological changes of trabecular resorption for cement‐bone interdigitated regions. The goal here was to evaluate the relevance of this model compared with human knee replacement with regards to func...

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Published inJournal of orthopaedic research Vol. 38; no. 7; pp. 1529 - 1537
Main Authors Mann, Kenneth A., Miller, Mark A., Tatusko, Megan E., Oest, Megan E.
Format Journal Article
LanguageEnglish
Published United States 01.07.2020
Subjects
cement
fixation
knee replacement
preclinical model
trabecular resorption
knee replacement
fixation
trabecular resorption
cement
preclinical model
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Summary:A preclinical rat knee replacement model was recently developed to explore the biological and mechanobiological changes of trabecular resorption for cement‐bone interdigitated regions. The goal here was to evaluate the relevance of this model compared with human knee replacement with regards to functional micromechanics. Eight nonsurvival, cemented knee replacement surgeries were performed, the interdigitated gap morphology was quantified, and interface micromotion between cement and bone was measured for 1 to 5 bodyweight loading. Computational fluid dynamics modeling of unit cell geometries with small gaps between trabeculae and cement was used to estimate fluid flow. Gap width (3.6 μm) was substantially smaller compared with cement‐bone gaps reported in human knee replacement (11.8 μm). Micromotion at the cement‐bone border was also decreased for the rat knee replacement (0.48 μm), compared with human (1.97 μm), for 1 bodyweight loading. However, the micromotion‐to‐gap width ratio (0.19 and 0.22 for, rat and human), and estimated fluid shear stress (6.47 and 7.13 Pa, for rat and human) were similar. Replicating the fluid dynamic characteristics of cement‐bone interdigitated regions in human knee replacements using preclinical models may be important to recapitulate trabecular resorption mechanisms due to proposed supraphysiologic fluid shear stress. Statement of clinical significance: local cement‐bone micromotion due to joint loading may contribute to the process of clinical loosening in total joint replacements. This work shows that while micromotion and gap morphology are diminished for the rat knee model compared to human, the motion‐to‐gap ratio, and corresponding fluid shear stress are of similar magnitudes
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Author Contributions Statement: Implantation surgery was performed by KA Mann, MA Miller, and ME Oest. Functional micromechanics loading experiments were performed by MA Miller. Digital image correlation analysis was performed by MA Miller and ME Tatusko. Data analysis and statistics were performed by KA Mann, MA Miller, ME Tatusko. Computational modeling was performed by KA Mann. Results interpretation was performed by KA Mann and ME Oest. Manuscript was written by KA Mann and ME Oest with input from all authors.
ISSN:0736-0266
1554-527X
DOI:10.1002/jor.24661