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.

ISO 14243是膝关节假体磨损测试的主要标准，但是在正确的前后位置（AP）位移和载荷方向以及正确的胫骨旋转（TR）角度和扭矩方向上存在争议。这项研究旨在分析改变AP和TR的方向如何影响胫骨插入物的磨损。还建议对ISO 14243-1和ISO 14243-3中指定的条件进行修改。因此，将五种加载条件应用于膝关节假体的FEA模型：（1）修改后的ISO 14243–3（具有正AP位移和TR角），（2）ISO 14243-3：2004（具有负的AP位移和TR角正， （3）ISO 14243–3：2014，AP位移为正，TR角为负；（4）修正的ISO 14243–1，AP载荷和TR为正，（5）ISO 14243–1：2009年，带有负AP负载和正TR扭矩。这项研究发现，根据ISO 14243-1和14243-3更改AP和TR的输入方向会对胫骨插入模型的磨损率和磨损轮廓产生影响。但是，磨损程度会根据胫骨插入物的设计特征和输入曲线的形状而有所不同。对于根据ISO 14243-3进行的位移控制，改变AP位移的方向对磨损率有显着影响（272.77％），但是改变TR角的方向影响很小（2.17％）。对于根据ISO 14243-1进行的负载控制，与修改后的ISO 14243-1条件相比，反向AP负载（ISO 14243-1：2009）仅将磨损率提高了6.73％。这项研究的临床意义是，结果表明胫骨磨损受AP和TR的应用方向影响。在设计阶段错误地施加加载条件可能导致无效的临床前评估，并可能随后影响植入物在临床上的寿命。