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

Abstract

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 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.

A review of recent advances in tribology

“…Other interesting developments included the direct observation of the lubricant film at the articulating surfaces using optical methods [354]. Furthermore, development of integrated computational and experimental methods [355] was also found to be necessary in order to balance the cost and the efficiency. In some applications where early interventions to cartilage repair were sought, natural tissues also became part of the bearing surfaces that were required to be included in the experimental testing [356].…”

Effects of interference assembly of a tibial insert on the tibiofemoral contact mechanics in total knee replacement

“…Wear on the articular surface of the tibial insert is related to the contact stress and cross-shear sliding movement, 22 and wear on the backside surface of the tibial insert is related to the micromotion at the interface between the tibial tray and the UHMWPE insert. 17 The backside micromotion was limited by the interference fit between the tibial tray and the UHMWPE insert, and increase in the amount of interference fit resulted in decrease in cumulative backside micromotion, 17 which would reduce the backside wear.…”

Wear properties of poly‐ether‐ether‐ketone bearing combinations under zero and cross shear kinematics in total knee arthroplasty

“…Although M-on-P bearings are currently the gold standard for knee replacements, polyethylene 211 wear resulting in osteolysis and aseptic loosening remains an important issue. In order to assess 212 PEEK as a potential bearing this study has compared the effects of uni-directional motion (zero 213 CS) and multi-directional motion (CS) on PK-on-PK and PK-on-M bearing couples under identical, physiologically relevant test conditions with a contact pressure of 5.7 MPa, similar 215 to that during normal gait following a TKR 22 . However, it should be noted that peak contact 216 stresses, > 25 MPa, found during stair climb or squatting (deep flexion) are also possible in-217 vivo 30 .…”

“…found PEEK appeared to have a cross shear dependency with the wear of PEEK increasing 84 with an increase in CS ratio, however, this was not reported as statistically significant. In the 85 present study, a clear comparison between PK-on-PK and PK-on-M bearing couples under 86 physiologically relevant wear conditions, as may be expected in-vivo during standard gait 87 following a TKR, is reported 22 . 88…”