The impact of variations in input directions according to ISO 14243 on wearing of knee prostheses

Abstract

ISO 14243 is the governing standard for wear testing of knee prostheses, but there is controversy over the correct direction of anterior-posterior (AP) displacement and loading and the correct direction of tibial rotation (TR) angles and torque. This study aimed to analyze how altering the direction of AP and TR affected wear on the tibial insert. Modifications to the conditions specified in ISO 14243–1 and ISO 14243–3 were also proposed. As such, five loading conditions were applied to FEA models of a knee prosthesis: (1) Modified ISO 14243–3 with positive AP displacement and TR angle, (2) ISO 14243–3:2004 with negative AP displacement and positive TR angle, (3) ISO 14243–3:2014 with positive AP displacement and negative TR angle, (4) Modified ISO 14243–1 with positive AP load and TR torque, and (5) ISO 14243–1:2009 with negative AP load and positive TR torque. This study found that changing the input directions for AP and TR according to ISO 14243–1 and 14243–3 had an influence on the wear rate and wear contours on the tibial insert model. However, the extent of wear varies depending on the design features of the tibial insert and shape of the input curves. For displacement control according to ISO 14243–3, changing the direction of AP displacement had a marked influence on the wear rate (272.77%), but changing the direction of TR angle had a much lower impact (2.17%). For load control according to ISO 14243–1, reversing the AP load (ISO 14243–1:2009) only increased the wear rate by 6.73% in comparison to the modified ISO 14243–1 conditions. The clinical relevance of this study is that the results demonstrate that tibial wear is affected by the direction of application of AP and TR. Incorrect application of the loading conditions during the design stage may lead to an ineffective preclinical evaluation and could subsequently influence implant longevity in clinical use.

Towards the understanding of lubrication mechanisms in total knee replacements – Part I: Experimental investigations

“…This includes the study of the formation and retention of lubricant films. Ideally, tribological testing should conform to ISO 14243 [30], [31], which is an established standard for wear rate assessment of knee replacements [32]. The main motivation of using standardized conditions is in ability of comparison of the findings and data across various simulators, approaches and methodologies.…”

Optimal Conformity Design of Tibial Insert Component Based on ISO Standard Wear Test Using Finite Element Analysis and Surrogate Model

“…The previous studies performed experiments to compare the knee simulator using simulation with the ISO-14243 standard, which has similar wear volume and scrap area values. The simulation showed wear volume at 1 million cycles for the analysis of wear of TKA [23]. The conclusion of this study indicated that the finite element method could aid the design analysis of TKA, which is reliable and accurate.…”

“…The ISO-14243 standard test was used widely for TKA testing to inspect the amount of wear volume on the implant. The standard has developed and changed parameters until the last standard was ISO-14243:2014 [23].…”

“…As shown in Figure 1, the FE of the femoral and tibial insert components were virtually arranged based on the adjusted position of the lowest surface of the femoral articular being on the tibial insert. For the boundary condition, the applied load were performed based on the ISO-14243-3:2014 standard of knee wear implant test [23], as shown in Figures 1 and 2. The wear simulation included dynamic loads in various directions and data from a human walking investigation that led to the TKA standard test.…”

Transient mixed lubrication model of the human knee implant

“…Transient loading conditions used in this work are those derived from ISO 14243‐3 for a total duration of 1 s [34]. The following data was obtained from the gait cycle and shown in Figures 4 and 5 [35].…”