Endurance Behavior of Cemented Tibial Tray Fixation Under Anterior Shear and Internal-External Torsional Shear Testing: A New Methodological Approach.

Background: Early total knee arthroplasty failures continue to surface in the literature. Cementation technique and implant design are two of the most important scenarios that can affect implant survivorship. Our objectives were to develop a more suitable preclinical test to evaluate the endurance of the implant-cement-bone interface under anterior shear and internal-external (I/E) torsional shear testing condition in a biomechanical sawbones.

Influence of radiation conditions on the wear behaviour of Vitamin E treated UHMWPE gliding components for total knee arthroplasty after extended artificial aging and simulated daily patient activities.

The long term performance of total knee arthroplasty (TKA) with regards to the bearing materials is related to the aging behaviour of these materials. The use of highly crosslinked materials in hip arthroplasty improved the clinical outcome. Nevertheless, the outcome for these materials compared to conventional UHMWPE (ultra-high molecular weight polyethylene) remains controversial in TKA and alternative bearing materials may be advantageous to improve its outcome in the second and third decade.

Metal ion release barrier function and biotribological evaluation of a zirconium nitride multilayer coated knee implant under highly demanding activities wear simulation.

Total knee arthroplasty is a well established treatment for degenerative joint disease, which is also performed as a treatment in younger and middle-aged patients who have a significant physical activity and high life expectancy. However, complications may occur due to biological responses to wear particles, as well as local and systemic hypersensitivity reactions triggered by metal ions and particles such as cobalt, chromium and molybdenum. The purpose of the study was to perform a highly demanding activities (HDA) knee wear simulation in order to compare the wear characteristics and metal ion release barrier function of a zirconium nitride (ZrN) coated knee implant, designed for patients with suspected metal ion hypersensitivity, against an uncoated knee implant made out of CoCrMo.

Vitamin E stabilised polyethylene for total knee arthroplasty evaluated under highly demanding activities wear simulation.

Unlabelled: As total knee arthroplasty (TKA) patients are getting more active, heavier and younger and structural material fatigue and delamination of tibial inserts becomes more likely in the second decade of good clinical performance it appears desirable to establish advanced pre-clinical test methods better characterizing the longterm clinical material behaviour. The questions of our study were 1) Is it possible to induce subsurface delamination and striated pattern wear on standard polyethylene TKA gliding surfaces? 2) Can we distinguish between γ-inert standard polyethylene (PEstand.30kGy) as clinical reference and vitamin E stabilised materials (PEVit.

CR TKA UHMWPE wear tested after artificial aging of the vitamin E treated gliding component by simulating daily patient activities.

The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty.

Evaluation of impingement behaviour in lumbar spinal disc arthroplasty.

Introduction: The objective of our in vitro study was to introduce a test method to evaluate impingement in lumbar spinal disc arthroplasty in terms of wear, contact pattern, metal ion concentration and particle release.

Material And Method: Impingement wear simulation was performed on a 6-station spinal wear simulator (Endolab, Germany) on a lumbar spinal disc system (activ L Aesculap AG, Germany) using four different protocols specific to impingement in flexion, in extension, in lateral bending and in combined flexion bending. Impingement contact stress is intentionally created by applying an angular displacement of +2° in addition to the intended range of motion in the impingement direction, whereas a bending moment of 8 Nm remains constant during the impingement phase (plateau).

Biotribology of a mobile bearing posterior stabilised knee design--effect of motion restraint on wear, tibio-femoral kinematics and particles.

The objective of our study was to evaluate the impact of a biphaseal anterior-posterior (AP) and internal-external (IE) motion restraint system on the wear behaviour, tibio-femoral kinematics and particle release of a mobile bearing posterior stabilised knee design in comparison to the widely used linear restraint. in vitro wear simulation was performed using a posterior stabilised total knee replacement with a mobile rotating platform gliding surface design to compare the standard ISO 14243-1:2002 (E) protocol with a linear AP and IE motion restraint and the new ISO 14243-1:2009 (E) protocol with a biphaseal AP and IE motion restraint. For the mobile gliding surfaces, an increase in wear rate by more than a magnitude was measured applying the biphaseal protocol (8.

The influence of third-body particles on wear rate in unicondylar knee arthroplasty: a wear simulator study with bone and cement debris.

The reduced intraoperative visibility of minimally invasive implanted unicondylar knee arthroplasty makes it difficult to remove bone and cement debris, which have been reported on the surface of damaged and retrieved bearings. Therefore, the aim of this study was to analyze the influence of bone and cement particles on the wear rate of unicompartmental knee prostheses in vitro. Fixed bearing unicompartmental knee prostheses were tested using a knee-wear-simulator according to the ISO standard 14243-1:2002(E) for 5.

Knee wear simulation under conditions of highly demanding daily activities--influence on an unicompartmental fixed bearing knee design.

The objectives of our in vitro study were to evaluate a knee wear simulation based on patient daily activities in combination with artificial ageing of polyethylene inserts to create an optimised simulation of in vivo wear modes. A wear simulation was performed on fixed bearing unicompartmental knee arthroplasty (UKA) devices in a direct comparison of level walking (as given by the ISO 14243-1:2002(E) profiles) and in a customised test configuration based on activities for level walking (10%), stairs ascending (40%), stairs descending (40%), chair rising (8%) and deep squatting (2%). The cumulative gravimetric wear was estimated to be 15.

Effect of anterior-posterior and internal-external motion restraint during knee wear simulation on a posterior stabilised knee design.

The objective of our study was to examine the effect of biphaseal AP translation and IE rotation restraint, using a system defined specifically for posterior stabilised knee designs, on wear, kinematics and particle release in comparison to linear motion restraint as required by the established ISO 14243-1:2002(E) protocol. In the ISOlinear groups, an AP motion restraint of 30 N/mm and an IE rotation restraint of 0.6 Nm/° were applied in the knee wear simulation.

Definition and evaluation of testing scenarios for knee wear simulation under conditions of highly demanding daily activities.

The objective of our study was the definition of testing scenarios for knee wear simulation under various highly demanding daily activities of patients after total knee arthroplasty. This was mainly based on a review of published data on knee kinematics and kinetics followed by the evaluation of the accuracy and precision of a new experimental setup. We combined tibio-femoral load and kinematic data reported in the literature to develop deep squatting loading profiles for simulator input.

Biotribology of alternative bearing materials for unicompartmental knee arthroplasty.

The objective of our wear simulator study was to evaluate the suitability of two different carbon fibre-reinforced poly-ether-ether-ketone (CFR-PEEK) materials for fixed bearing unicompartmental knee articulations with low congruency. In vitro wear simulation was performed according to ISO 14243-1:2002 (E) with the clinically introduced Univation F fixed bearing unicompartmental knee design (Aesculap AG, Tuttlingen, Germany) made of UHMWPE/CoCr29Mo6 in a direct comparison to experimental gliding surfaces made of CFR-PEEK pitch and CFR-PEEK PAN. Gliding surfaces of each bearing material (n=6+2) were gamma-irradiated, artificially aged and tested for 5 million cycles with a customized four-station knee wear simulator (EndoLab, Thansau, Germany).

Alternative bearing materials for intervertebral disc arthroplasty.

The objective of our study was to test alternative polymer-on-polymer articulations for cervical total disc arthroplasty with favourable biotribological properties and the benefit of radiolucency in comparison to the clinically well established metal-on-polyethylene coupling. In vitro wear simulation was performed according to ISO 18192-1:2008 (E) with the clinically introduced activ C cervical artificial disc (Aesculap AG Tuttlingen, Germany) made of UHMWPE/CoCr29Mo6 in a direct comparison to experimental disc articulations made of PEEK, CFR-PEEK and PEK. Each material combination was tested for 10 million cycles with a customised 6 station spinal wear simulator (EndoLab Thansau, Germany).

Fixed bearing knee congruency -- influence on contact mechanics, abrasive wear and kinematics.

The objective of our study was to evaluate the in vitro wear behavior of fixed bearing designs for total knee arthroplasty in relation to contact mechanics and resultant kinematics for different degrees of congruency. a finite element model was created for three knee articulations with increasing degrees of tibio-femoral congruency (flat, curved, and dished design). For the three different knee design configurations, in vitro wear simulation was performed according to iso 14243-1.

Biotribological evaluation of artificial disc arthroplasty devices: influence of loading and kinematic patterns during in vitro wear simulation.

Wear simulation is an essential pre-clinical method to predict the mid- and long-term clinical wear behavior of newly introduced devices for total disc arthroplasty. The main requirement of a suitable method for spinal wear simulation has to be the ability to distinguish between design concepts and allow for a direct comparison of predicate devices. The objective of our study was to investigate the influence of loading and kinematic patterns based on two different protocols for spinal wear simulation (ISO/FDIS 18192-1 (2006) and ASTM F2423-05).