Abstract
More robust preclinical 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 to fully meet and be 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/million cycles (MC; mean ± 95% confidence interval, p = 0.99) and 5.4 ± 1.4 and 6.7 ± 1.5 mm3/MC (mean ± 95 confidence interval, p = 0.54) from the electromechanical and pneumatic simulators under intermediate levels (maximum 5 mm) and high levels (maximum 10 mm) of anterior–posterior displacements, respectively. However, the output kinematic profiles of the control system, which drive 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). 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.
Highlights
Surface wear of polyethylene and the resulting osteolysis are still considered a long-term risk factor of total knee replacements (TKRs), as life expectancy and activity levels increase.[1]
Experimental wear simulation is an established method for evaluating the wear performance of total joint replacements, with numerous publications over the last decade demonstrating the influence of design, material, kinematics, and sterilisation processes on the performance of TKRs.[2,10,14,15,16,17,18]
This study investigated the wear of a fixed-bearing TKR using this second-generation electromechanically driven fully independent knee simulator and compared it to previous data from a first-generation predominantly pneumatically controlled simulator (ProSim knee simulator) that was not fully independently controlled
Summary
Surface wear of polyethylene and the resulting osteolysis are still considered a long-term risk factor of total knee replacements (TKRs), as life expectancy and activity levels increase.[1] Failed TKRs require expensive revision surgery, associated with a higher risk of post-surgery complications than the primary surgery.[2,3,4,5,6] The number of recorded TKR revisions in 2014 in the United Kingdom was 3239.7 Unsurprisingly, the revision rate for young patients (under 55 years) was 10 times that for patients over 75 years.[7] The current. International standard for preclinical knee wear simulation has been based on the average patient and walking gait activity.[8,9] In an attempt to address and understand the higher failure rates reported for young patients, preclinical testing methods which include a wider range of physiological conditions have been developed.[10,11,12,13]. Evaluate, and reduce failure rates, it is necessary to use adverse conditions in in vitro simulations.[10,24]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
