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In vivo loss of cement–bone interlock reduces fixation strength in total knee arthroplasties
Author(s) -
Goodheart Jacklyn R.,
Miller Mark A.,
Mann Kenneth A.
Publication year - 2014
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.22634
Subject(s) - fixation (population genetics) , implant , cement , bone cement , biomedical engineering , dentistry , materials science , medicine , surgery , composite material , population , environmental health
Prevention of aseptic loosening of total knee arthroplasties (TKAs) remains a clinical challenge. Understanding how changes in morphology at the implant–bone interface with in vivo service affect implant stability and strength could lead to new approaches to mitigate loosening. Enbloc TKA retrievals and freshly‐cemented TKA tibial components were used to determine if the mechanical strength of the interface depended on the amount of cement–bone interlock and the morphology of the supporting bone under the cement layer. Implants were sectioned into small specimens of the cement–interface–bone from under the tibial tray. Micro‐CT scans were used to document interlock morphology and architecture of the supporting trabecular bone. Axial compression tests were used to assess mechanical behavior. Postmortem retrievals had lower contact fraction (42 ± 55%) compared to freshly‐cemented constructs (121 ± 61%) ( p = 0.0008). Supporting bone architecture parameters were not different for the two groups. Increased interface contact fraction and supporting bone volume fraction (BV/TV) were positive predictors of interface strength ( r 2 = 0.72, p = 0.0001). For the same supporting bone BV/TV, postmortem specimens had weaker interfaces; they were also more compliant. Cemented TKAs with in vivo service experience a loss of fixation strength and increased micro‐motion due to the loss of cement–bone interlock. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1052–1060, 2014.