A Comparison in Proximal Tibial Strain Between Metal-Backed and All-Polyethylene Anatomic Graduated Component Total Knee Arthroplasty Tibial Components
Section snippets
Materials and Methods
Metal-backed and all-polyethylene AGC Total Knee Systems were used in this study. Sawbones Third Generation composite tibiae (Pacific Research Laboratories, Inc, Vashon, Wash) designed to replicate the mechanical properties of cadaveric bone were chosen as test specimens to minimize interspecimen sizing and bone density variability [9]. Five left tibiae for each prosthesis type were implanted by a board-certified orthopedic surgeon 5 mm below the joint line with 75-mm-sized AGC tibial
Results
Least square means of shear strain values in each of the 24 measurement regions on the proximal tibia are reported for the 50:50 and 80:20 loading distributions in Table 1, Table 2, respectively. In this study, there were no measurement regions in any experimental group or loading condition that showed statistically significant higher shear strains in the metal-backed implanted tibiae when compared to the all-polyethylene implanted tibiae (Fig. 4, Fig. 5). The highest values of shear strain
Discussion
We have previously reported a 98% fifteen-year survival rate with the nonmodular metal-backed AGC total knee prosthesis, in a study of 4583 knees, whereas we found only a 68% ten-year survival rate in a study 536 knees with AGC all-polyethylene tibial components 4, 5. Taylor et al [13] hypothesized that excessive stresses in the proximal tibia could lead to prosthesis migration and cancellous bone failure, which is the most common failure mechanism observed for AGC all-polyethylene implants. [4]
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Cited by (19)
Quantifying the immediate post-implantation strain field of cadaveric tibiae implanted with cementless tibial trays: A time-elapsed micro-CT and digital volume correlation analysis during stair descent
2024, Journal of the Mechanical Behavior of Biomedical MaterialsUnicompartmental Knee Arthroplasty: US and Global Perspectives
2020, Orthopedic Clinics of North AmericaCitation Excerpt :In a randomized trial between all-polyethylene and metal-backed tibial trays, the all-polyethylene design had a 37% incidence of aseptic loosening.64 This may be attributed to the more focal tibial loading seen in these designs.65 Surgeons must be cautious of interpreting all radiolucencies as aseptic loosening, which is discussed below.
Analysis of an early intervention distal femoral resurfacing implant for medial osteoarthritis
2016, Journal of BiomechanicsCitation Excerpt :Nevertheless, this has not always applied to total knees where no differences in loosening have been noted between all-plastic and metal-backed in the long term in some series (Doran et al., 2015). Higher stresses have also been measured on the surface of the proximal tibia when comparing all-poly with metal-backed components (Small et al., 2010). It is not easy to reconcile those results with the finite element data however because with all-plastic, the higher interface stresses and strains are restricted to the central region rather than around the periphery.
Metal Backing Significantly Decreases Tibial Strains in a Medial Unicompartmental Knee Arthroplasty Model
2011, Journal of ArthroplastyCitation Excerpt :The early mean time to failure seems to suggest mechanical factors to be significant contributors in these specific failure mechanisms in both TKA and UKA. Separate studies have correlated the presence of metal backing with improve tibial loading distribution in TKA [18,26]. The current study evaluated the bony loading response of the medial tibial beneath the operative condyle in UKA.
No benefits or funds were received in support of the study.