Progressive loss of implant fixation in a preclinical rat model of cemented knee arthroplasty

• Published in: Journal of orthopaedic research Vol. 39; no. 11; pp. 2353 - 2362
• Main Authors: Mann, Kenneth A., Miller, Mark A., Rossow, Jeffrey K., Tatusko, Megan E., Horton, Jason A., Damron, Timothy A., Oest, Megan E.
• Format: Journal Article
• Language: English
• Published: United States 01.11.2021
• Subjects: Animals; Arthroplasty, Replacement, Knee - methods; Bone Cements; Bone Resorption; cement; fixation; knee arthroplasty; Knee Prosthesis; morphology; osteolysis; preclinical model; Prosthesis Failure; Rats; Rats, Sprague-Dawley; Tibia - surgery; fixation; knee arthroplasty; cement; preclinical model; morphology; osteolysis
• ISSN: 0736-0266; 1554-527X
• DOI: 10.1002/jor.24977

Aseptic loosening of total knee arthroplasty continues to be a challenging clinical problem. The progression of the loosening process, from the initial well‐fixed component, is not fully understood. In this study, loss of fixation of cemented hemiarthroplasty was explored using 9‐month‐old Sprague–Dawley rats with 0, 2, 6, 12, 26 week end points. Morphological and cellular changes of cement–bone fixation were determined for regions directly below the tibial tray (epiphysis) and distal to the tray (metaphysis). Loss of fixation, with a progressive increase in cement–bone gap volume was found in the epiphysis (0.162  mm3/week), but did not progress appreciably in the metaphysis (0.007 mm3/week). In the epiphysis, there was an early and sustained elevation of osteoclasts adjacent to the cement border and development of a fibrous tissue layer between the cement and bone. There was early formation of bone around the cement in the metaphysis, resulting in a condensed bone layer without osteoclastic bone resorption or development of a fibrous tissue layer. Implant positioning was also an important factor in the cement–bone gap formation, with greater gap formation for implants that were placed medially on the tibial articular surface. Loss of fixation in the rat model mimicked patterns found in human arthroplasty where cement–bone gaps initiate under the tibial tray, at the periphery of the implant. This preclinical model could be used to study early biological response to cemented fixation and associated contributions of mechanical instability, component alignment, and periprosthetic inflammation. A longitudinal study of cemented hemiarthroplasty was explored using 9‐month‐old Sprague–Dawley rats with 0, 2, 6, 12, 26 week end points. Loss of fixation, with a progressive increase in cement–bone gap volume was found in the epiphysis (0.162 mm3/week) of the proximal tibia, but did not progress appreciably in the metaphysis (0.007 mm3/week). Loss of fixation in the rat model mimiced patterns found in human arthroplasty where radiolucencies initiate at the periphery of the implant, under the tibial tray.