The influence of simulator input conditions on the wear of total knee replacements: An experimental and computational study

Abstract

Advancements in knee replacement design, material and sterilisation processes have provided improved clinical results. However, surface wear of the polyethylene leading to osteolysis is still considered the longer-term risk factor. Experimental wear simulation is an established method for evaluating the wear performance of total joint replacements. The aim of this study was to investigate the influence of simulation input conditions, specifically input kinematic magnitudes, waveforms and directions of motion and position of the femoral centre of rotation, on the wear performance of a fixed-bearing total knee replacement through a combined experimental and computational approach. Studies were completed using conventional and moderately cross-linked polyethylene to determine whether the influence of these simulation input conditions varied with material. The position of the femoral centre of rotation and the input kinematics were shown to have a significant influence on the wear rates. Similar trends were shown for both the conventional and moderately cross-linked polyethylene materials, although lower wear rates were found for the moderately cross-linked polyethylene due to the higher level of cross-linking. The most important factor influencing the wear was the position of the relative contact point at the femoral component and tibial insert interface. This was dependent on the combination of input displacement magnitudes, waveforms, direction of motion and femoral centre of rotation. This study provides further evidence that in order to study variables such as design and material in total knee replacement, it is important to carefully control knee simulation conditions. This can be more effectively achieved through the use of displacement control simulation.

A patient-specific wear prediction framework for an artificial knee joint with coupled musculoskeletal multibody-dynamics and finite element analysis

“…Thirdly, due to the lack of the relevant patient specific ligament properties, generic values were taken from the literature, and the ligament origin and insertion points were located manually to fit the patient's bone geometries according to anatomic descriptions. Fourthly, although the wear model has been verified with experiments [1,46,54], the predicted wear volumes were 31%-45% lower than the experimental results [32], and the experimental simulator results may be even smaller than the retrieved TKR [55]. The improvement of the wear model may provide an even more realistic coupled framework.…”

A comprehensive combined experimental and computational framework for pre-clinical wear simulation of total knee replacements

“…In an attempt to understand and address the higher failure rates reported for young patients, pre-clinical experimental testing methods which include a wider range of physiological conditions have been developed ( Jennings et al, 2007 , Nakamura et al, 2009 , Schwiesau et al, 2013 , r et al, 2014 ). In contrast to the pin-on-plate and pin-on-disk testers, experimental wear tests are run on the full size replacement and under complex and physiologically relevant test conditions ( Galvin et al, 2009 , Fisher et al, 2010 , Brockett et al, 2012 , Brockett et al, 2016b , Jennings et al, 2012 ). Such in-vitro testing is an invaluable method for evaluating bearing materials and total knee replacement geometries.…”

“…Computational wear modelling has been extensively used for pre-clinical wear simulation in TKR ( Barbour et al, 1995 , Fregly et al, 2005 , Abdelgaied et al, 2011 , Abdelgaied et al, 2014 , Brockett et al, 2013 , Brockett et al, 2016b ), with the low cost and time as well as its appropriateness for parametric studies ( Willing and Kim, 2009b , Abdelgaied et al, 2011 ). Based on wear factor, sliding distance, applied load, contact area, and contact stress, the simplified ( Barbour et al, 1995 , Maxian et al, 1996 , Knight et al, 2007 , Pal et al, 2008 , Zhao et al, 2008 ) as well as modified ( Willing and Kim, 2009b , Innocenti et al, 2014 ) versions of Archard’s wear law ( Archard and Hirst, 1956 ) have been adopted in many studies to predict wear in total joint replacements.…”

Comparison of CMM and Micro-CT Volumetric Analysis of Polyethylene Tibial Knee Inserts in Total Knee Replacement

“…The wear tests were carried out by a colleague within the research institution (C. Brockett) in 2009 and 2011 [10]. Two input profiles were used for the specimens, one is the ISO setup and the other is a standard CR150.…”