The dataset contains material to supplement the paper “Understanding the differences in wear testing method standards for total knee replacement” including: images of Figures 1 to 12 inclusive; the graphical abstract; the raw data underpinning the figures; additional points throughout the cycle to supplement Figure 4.b: (Computational contact scars at 15%, 50%, and 85% through the gait cycle using different displacement control test methods are presented in Figure 4b, this additional data shows computational contact scars at every 5% interval) and Figure 10.b: (Computational contact scars at 15%, 50%, and 85% through the gait cycle using ISO-14243-1-2009 force control test method are presented in Figure 10b, this additional data shows computational contact scars at every 5% interval)

A more robust pre-clinical wear simulation framework is required in order to simulate wider and higher ranges of activities, observed in different patient populations such as younger more active patients. Such a framework will help to understand and address the reported higher failure rates for younger and more active patients (National_Joint_Registry, 2016). The current study has developed and validated a comprehensive combined experimental and computational framework for pre-clinical wear simulation of total knee replacements (TKR). The input mechanical (elastic modulus and Poisson’s ratio) and wear parameters and of the moderately cross-linked ultra-high molecular weight polyethylene (UHMWPE) bearing material were independently measured from experimental studies under realistic test conditions, similar to the loading conditions found in the total knee replacements.. The wear predictions from the computational wear simulation were validated against the direct experimental wear measurements for size 3 Sigma curved total knee replacements (DePuy, UK) in an independent experimental wear simulation study under three different daily activities; walking, deep squat, and stairs ascending kinematic conditions. The measured compressive mechanical properties of the moderately cross-linked UHMWPE material were more than 20% lower than that reported in the literature under tensile test conditions. The pin-on-plate wear coefficient of moderately cross-linked UHMWPE was significantly dependant of the contact stress and the degree of cross-shear at the articulating surfaces. The computational wear predictions for the TKR from the current framework were consistent and in a good agreement with the independent full TKR experimental wear simulation measurements, with 0.94 coefficient of determination of the framework. In addition, the comprehensive combined experimental and computational framework was able to explain the complex experimental wear trends from the three different daily activities investigated. Therefore, such a framework can be adopted as a pre-clinical simulation approach to optimise different designs, materials, as well as patient’s specific total knee replacements for a range of activities.

Data set for paper 'Representing the effect of variation in soft tissue constraints in experimental simulation of total knee replacements';. Data includes experimental results from a knee simulator that are represented in the figures and text of the paper.

More robust pre-clinical experimental wear simulation methods are required in order to simulate a wider range of activities, observed in different patient populations such as younger more active patients, as well as fully meeting and being capable of going well beyond the existing requirements of the relevant international standards. A new six station electromechanically driven simulator (Simulation Solutions, UK) with five fully independently controlled axes of articulation for each station, capable of replicating deep knee bending as well as other adverse conditions, which can be operated in either force or displacement control with improved input kinematic following, has been developed to meet these requirements. This study investigated the wear of a fixed bearing total knee replacement using this electromechanically driven fully independent knee simulator, and compared it to previous data from a predominantly pneumatically controlled simulator in which each station was not fully independently controlled. In addition, the kinematic performance and the repeatability of the simulators have been investigated and compared to the international standard requirements. The wear rates from the electromechanical and pneumatic knee simulators were not significantly different, with wear rates of 2.6 ± 0.9 and 2.7 ± 0.9 [mm3/MC] (mean ± 95% CI, p=0.99) and 5.4 ± 1.4 and 6.7 ± 1.5 [mm3/MC] (mean ± 95% CI, p=0.54) from the electromechanical and pneumatic simulators, under intermediate levels (maximum 5 mm) and high levels (maximum 10 mm) of AP displacements respectively. However, the output kinematic profiles of the control system, which drives the motion of the simulator followed the input kinematic profiles more closely on the electromechanical simulator than the pneumatic simulator. In addition, the electromechanical simulator was capable of following kinematic and loading input cycles within the tolerances of the international standard requirements (ISO 14243-3, 2014). The new generation electromechanical knee simulator with fully independent control has the potential to be used for a much wider range of kinematic conditions, including high-flexion and other severe conditions, due to its improved capability and performance in comparison to the previously used pneumatic controlled simulators.

Pin on plate studies to understand the influence of contact pressure, cross shear and counterface were undertaken with surface analysis measured prior to test and at completion. Mean wear factors for each condition were calculated at the completion of the study. This dataset includes the mean wear factor for each condition and the surface roughness measurements.