In vitro models of arthroplasty enable pre-clinical testing and inform clinical decision making. Repeated-measures comparisons maximise resource efficiency, but their validity without testing order randomisation is not known. This study aimed to identify if there were any large testing order effects for cadaveric models of knee and hip arthroplasty. First, the effect of testing order on total knee arthroplasty (TKA) biomechanics was assessed. Extension moments for TKAs (N = 3) implanted into the native knee (TKA-only) were compared to a dataset of TKAs (N = 24) tested after different combinations of partial knee arthroplasty (TKA-last). The effect of repeatedly testing the same knee five times over 36 h on patellofemoral and tibiofemoral kinematics was also quantified. Second, the effect of testing order on capsular ligament function after total hip arthroplasty (THA) was assessed. Randomisation was removed from a previously published dataset to create increasing and decreasing head size groups, which were compared with t-tests.

All three TKA-only extension moments fell within the 95% CI of the TKA-last knees across the full range of knee flexion/extension. Repeated testing resulted in root-mean-squared kinematics errors within 1 mm, 1°, or < 5 % of total range of motion. Following THA, smaller head-size resulted in greater laxity in both the increasing (p = 0.01) and decreasing (p < 0.001) groups. Testing order did not have large effects on either knee or hip arthroplasty biomechanics measured with in vitro cadaveric models.

关节成形术的体外模型能够进行临床前测试并为临床决策提供信息。重复测量比较可以最大限度地提高资源效率，但在没有测试顺序随机化的情况下它们的有效性尚不清楚。本研究旨在确定膝关节和髋关节置换术的尸体模型是否存在任何大的测试顺序效应。首先，评估了测试顺序对全膝关节置换术 (TKA) 生物力学的影响。将植入天然膝关节（仅 TKA）的 TKA（N = 3）的伸展力矩与在不同的部分膝关节置换术（TKA-last）组合后测试的 TKA（N = 24）数据集进行比较。还量化了在 36 小时内重复测试同一个膝盖五次对髌股和胫股运动学的影响。第二，评估了测试顺序对全髋关节置换术 (THA) 后关节囊韧带功能的影响。从先前发布的数据集中删除随机化以创建增加和减少的头部大小组，并将其与 t 检验进行比较。

在膝关节屈曲/伸展的整个范围内，所有三个仅使用 TKA 的伸展力矩都落在最后使用 TKA 的膝关节的 95% CI 内。重复测试导致运动学均方根误差在 1 毫米、1° 或 < 5  % 的总运动范围内。在 THA 之后，较小的头部尺寸在增加 (p = 0.01) 和减少 (p < 0.001) 组中导致更大的松弛。测试顺序对用体外尸体模型测量的膝关节或髋关节置换术生物力学没有太大影响。